阅读说明：本技术 乙酸的制备方法 (The preparation method of acetic acid ) 是由 清水雅彦 于 2018-07-02 设计创作，主要内容包括：本发明提供能够在洗涤系统中有效地分离取得碘甲烷和吸收溶剂、不易发生蒸馏塔内部的腐蚀、可有效地分离回收碘化氢和碘甲烷、或能够充分地回收碘化氢的乙酸的制备方法。本发明的乙酸的制备方法包括：使废气与包含碳原子数2以上的醇、碳原子数3以上的羧酸的酯、羧酸与碳原子数2以上的醇的酯、醚、酮、水、或碱性水溶液的第1吸收剂接触而使废气中的碘化合物吸收于第1吸收剂从而得到第1气体成分的第1吸收工序；和使第1气体成分与包含碳原子数2以上的醇、碳原子数3以上的羧酸的酯、醚、羧酸与碳原子数2以上的醇的酯、酮、水、碱性水溶液、或乙酸的不同于第1吸收剂的第2吸收剂接触而使第1气体成分中的碘化合物吸收于第2吸收剂的第2吸收工序。(The present invention provides to efficiently separate in washing system and obtains iodomethane and lyosoption, the burn into being not susceptible to inside destilling tower can efficiently separate recycling hydrogen iodide and iodomethane or can fully recycle the preparation method of the acetic acid of hydrogen iodide.The preparation method of acetic acid of the invention includes: that exhaust gas is made to contact with the alcohol comprising 2 or more carbon atom number, the ester of the carboxylic acid of 3 or more carbon atom number, carboxylic acid with the 1st absorbent of the ester of the alcohol of 2 or more carbon atom number, ether, ketone, water or alkaline aqueous solution and so that the iodine compound in exhaust gas is absorbed in the 1st absorbent to obtain the 1st of the 1st gas componant the and absorb process；So that the iodine compound in the 1st gas componant is absorbed in the 2nd of the 2nd absorbent with the 1st gas componant is contacted with the 2nd absorbent different from the 1st absorbent of the ester of the alcohol of 2 or more carbon atom number, ketone, water, alkaline aqueous solution or acetic acid with the alcohol comprising 2 or more carbon atom number, the ester of the carboxylic acid of 3 or more carbon atom number, ether, carboxylic acid and absorb process.)

1. the preparation method of acetic acid includes that the 1st absorption process and the 2nd absorb process in the preparation process of acetic acid,

It is absorbed in process the described 1st, at least part of the exhaust gas generated in technique is supplied to absorption tower, itself and packet are made The ester of ester, carboxylic acid containing the carboxylic acid selected from the alcohol of 2 or more carbon atom number, 3 or more carbon atom number and the alcohol of 2 or more carbon atom number, 1st absorbent of one or more of ether, ketone, water and alkaline aqueous solution liquid contacts and makes the iodine compound in the exhaust gas Be absorbed in the 1st absorbent, thus be separated into the 1st gas componant that the iodine compound concentration compared with the exhaust gas reduces, With the 1st solution comprising the 1st absorbent and iodine compound；

It is described 2nd absorb process in, make the 1st gas componant absorption tower with comprising selected from 2 or more carbon atom number alcohol, Ester, ether, ketone, water, alkaline aqueous solution and the second of the alcohol of the ester of the carboxylic acid of 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number One or more of acid liquid and composition 2nd absorbent different with the 1st absorbent contacts and make the 1st gas componant In iodine compound be absorbed in the 2nd absorbent, dropped to be separated into compared with the 1st gas componant iodine compound concentration The 2nd low gas componant and the 2nd solution comprising the 2nd absorbent and iodine compound.

2. the preparation method of acetic acid comprising:

In the presence of the catalyst system comprising metallic catalyst and iodomethane and acetic acid, methyl acetate, water, make methanol and Carbon monoxide reacts in reactive tank and generates the carbonylation process of acetic acid；With

It, will the reaction mixture obtained in the carbonylation process using more than one evaporator tank and/or destilling tower It is separated into the stream comprising metallic catalyst, the acetic acid stream of enrichment acetic acid and low boiling ingredient is more enriched with compared with the acetic acid stream Stream separation process,

In the preparation method,

Optionally further comprise: using more than one destilling tower, is obtained from by the stream condensation of the enrichment low boiling ingredient Condensate liquid at least part in separate acetaldehyde acetaldehyde be separated off system,

The preparation method includes that the 1st absorption process and the 2nd absorb process,

It is described 1st absorb process in, by selected from from the reactive tank discharge gas, from the discharge gas of the evaporator tank Body, the discharge gas of destilling tower in the separation process and the destilling tower that is separated off from the acetaldehyde in system One or more of discharge gas exhaust gas supply to absorption tower, make itself and alcohol, carbon atom comprising being selected from 2 or more carbon atom number One of ester, ether, ketone, water and alkaline aqueous solution of alcohol of the ester of the carboxylic acid of 3 or more number, carboxylic acid and 2 or more carbon atom number with 1st absorbent of upper liquid contacts and the iodine compound in the exhaust gas is made to be absorbed in the 1st absorbent, thus be separated into The 1st gas componant that the exhaust gas is reduced compared to iodine compound concentration and comprising the 1st absorbent and iodine compound the 1 solution；

It is described 2nd absorb process in, make the 1st gas componant absorption tower with comprising selected from 2 or more carbon atom number alcohol, Ester, ether, ketone, water, alkaline aqueous solution and the second of the alcohol of the ester of the carboxylic acid of 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number One or more of acid liquid and composition 2nd absorbent different with the 1st absorbent contacts and make the 1st gas componant In iodine compound be absorbed in the 2nd absorbent, dropped to be separated into compared with the 1st gas componant iodine compound concentration The 2nd low gas componant and the 2nd solution comprising the 2nd absorbent and iodine compound.

3. the preparation method of acetic acid according to claim 1 or 2, wherein the 1st absorbent includes water.

4. the preparation method of acetic acid described in any one of claim 1 to 3, wherein the 2nd absorbent includes second Acid.

5. the preparation method of acetic acid according to any one of claims 1 to 4, wherein in the 1st or the 2nd absorbent Water concentration be 10 mass ppm or more.

6. the preparation method of acetic acid according to any one of claims 1 to 5, wherein the 1st absorbent and the 2nd suction Water concentration in one of receipts agent is 10 mass ppm or more, the acetic acid concentration in another one is 10 mass ppm or more.

7. the preparation method of acetic acid described according to claim 1~any one of 6 comprising: the 2nd solution is steamed It evaporates and is separated into the tower top stream of enrichment iodomethane and is enriched with the diffusing procedure of the bottom product stream of acetic acid.

8. the preparation method of acetic acid according to claim 7, wherein the tower top stream of the enrichment iodomethane to be recycled to Reaction process.

9. the preparation method of acetic acid according to claim 7 or 8, wherein carry out the destilling tower of the diffusing procedure into Iodomethane concentration in feed liquid is 100 mass ppm or more.

10. the preparation method of the acetic acid according to any one of claim 7~9, wherein carry out the steaming of the diffusing procedure The concentration of hydrogen iodide in the feeding liquid of tower is evaporated lower than 100 mass ppm.

11. the preparation method of acetic acid comprising:

In the presence of the catalyst system comprising metallic catalyst and iodomethane and acetic acid, methyl acetate, water, make methanol and Carbon monoxide reacts in reactive tank and generates the carbonylation process of acetic acid；

The reaction mixture obtained in the carbonylation process is separated into the steaming of vapor stream and raffinate stream in evaporator tank Send out process；

The vapor stream is distilled and is separated into the tower top stream of enrichment low boiling ingredient and is enriched with the 1st acetic acid stream of acetic acid De- low boiling process；And

1st acetic acid stream is distilled and is separated into the tower top stream of enrichment water, 1 acetic acid stream of He Yu is more enriched with compared to acetic acid The 2nd acetic acid stream dehydration procedure,

In the preparation method,

Optionally further comprise: the 2nd acetic acid stream distilled and be separated into the bottom product stream for being enriched with high boiling ingredient and The 3rd acetic acid stream that acetic acid is more enriched with compared with the acetic acid stream before being distilled takes off high boiling process；And/or

Using more than one destilling tower, at least one of the condensate liquid obtained from by the stream condensation of the enrichment low boiling ingredient The acetaldehyde that acetaldehyde is separated in part is separated off system,

The preparation method includes that the 1st absorption process and the 2nd absorb process,

It is described 1st absorb process in, by selected from from the reactive tank discharge gas, from the discharge gas of the evaporator tank Body, the discharge gas of destilling tower in the de- low boiling process, destilling tower in the dehydration procedure discharge gas Body, the distillation being separated off from the discharge gas for taking off the destilling tower in high boiling process and from the acetaldehyde in system One or more of the discharge gas of tower exhaust gas is supplied to absorption tower, keeps it former with the alcohol comprising being selected from 2 or more carbon atom number, carbon One of the ester of the carboxylic acid of 3 or more subnumber, carboxylic acid and ester, ether, ketone, water and the alkaline aqueous solution of alcohol of 2 or more carbon atom number 1st absorbent of the above liquid contacts and the iodine compound in the exhaust gas is made to be absorbed in the 1st absorbent, to be separated into Iodine compound concentration reduces compared with the exhaust gas the 1st gas componant and comprising the 1st absorbent and iodine compound 1st solution；

It is described 2nd absorb process in, make the 1st gas componant absorption tower with comprising selected from 2 or more carbon atom number alcohol, Ester, ether, ketone, water, alkaline aqueous solution and the second of the alcohol of the ester of the carboxylic acid of 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number One or more of acid liquid and composition 2nd absorbent different with the 1st absorbent contacts and make the 1st gas componant In iodine compound be absorbed in the 2nd absorbent, dropped to be separated into compared with the 1st gas componant iodine compound concentration The 2nd low gas componant and the 2nd solution comprising the 2nd absorbent and iodine compound.

12. the preparation method of acetic acid according to claim 11, wherein the water concentration in the 1st or the 2nd absorbent is 10 mass ppm or more.

13. the preparation method of acetic acid according to claim 11 or 12, wherein in the 1st absorbent and the 2nd absorbent One of in water concentration be 10 mass ppm or more, the acetic acid concentration in another one is 10 mass ppm or more.

14. the preparation method of acetic acid described in any one of 1~13 according to claim 1, wherein follow the 1st solution again Ring is to the decanter selected from the reactive tank, for storing the condensate liquid, the destilling tower in the dehydration procedure and described de- More than one device in destilling tower in high boiling process.

15. the preparation method of acetic acid described in any one of 1~14 according to claim 1 comprising: by the 2nd solution into Row distills and is separated into the tower top stream of enrichment iodomethane and is enriched with the diffusing procedure of the bottom product stream of acetic acid.

16. the preparation method of acetic acid according to claim 15, wherein carry out the charging of the destilling tower of the diffusing procedure Iodomethane concentration in liquid is 100 mass ppm or more.

17. the preparation method of acetic acid according to claim 15 or 16, wherein carry out the destilling tower of the diffusing procedure Concentration of hydrogen iodide in feeding liquid is lower than 100 mass ppm.

18. the preparation method of acetic acid described in any one of 5~17 according to claim 1, wherein by the enrichment iodomethane Tower top stream is recycled to selected from one or more of the reaction process, evaporization process and distillation process process.

19. the preparation method of acetic acid described in any one of 5~18 according to claim 1, wherein by the tower of the enrichment acetic acid Kettle raffinate stream be recycled to selected from the reaction process, the evaporization process, the de- low boiling process, the dehydration procedure and Described more than one process taken off in high boiling process.

20. the preparation method of acetic acid described according to claim 1~any one of 19, wherein using different absorption towers into Row the described 1st absorbs process and the described 2nd and absorbs process.

Technical field

The present invention relates to the methods for preparing acetic acid.

Background technique

Industrial production process as acetic acid, it is known to methanol method carbonylating process (methanol method acetic acid process).In the work In skill, such as methanol and carbon monoxide can be made to react in reactive tank in the presence of a catalyst and generate acetic acid, make instead Answer mixture evaporated in evaporator tank and to its vapor phase using de- low boiling tower, purified and realized followed by dehydrating tower The product of acetic acid, or can realize the system of acetic acid via product tower via de- high boiling tower or further after dehydrating tower Product.

In such acetic acid preparation process, the exhaust gas from the techniques such as reaction system or purification system includes useful component (for example, iodomethane, water, methyl acetate, acetic acid etc.).Therefore, for above-mentioned exhaust gas, such as lyosoption is utilized in washing system Absorb processing and will be discarded again after the recycling of these useful components.It but also include hydrogen iodide in above-mentioned exhaust gas.Hydrogen iodide quilt Think will lead to the device in acetic acid preparation process, corrode inside equipment, or can cause when being discharged into extraneous gas Environmental problem.Therefore, it is necessary to also remove hydrogen iodide from exhaust gas.

The preparation method of acetic acid is disclosed in patent document 1 comprising: make specific technique stream and is selected from acetic acid, methanol And the 1st absorbent contact in methyl acetate, or further contacted with the 2nd absorbent comprising methanol and/or methyl acetate, Thus hydrogen iodide is removed from technique stream.

Summary of the invention

Problems to be solved by the invention

The solution for absorbing useful component is subsequently fed to be separated into useful component and suction in destilling tower and by distillation Receive solvent.By the distillation, the useful components such as iodomethane are usually concentrated into overhead stream, have passed through the iodomethane of concentration It is recycled to reactive tank and is recycled in reaction process.

However, using the case where methanol or methyl acetate are as lyosoption in the method disclosed in patent document 1 Under, the boiling-point difference of lyosoption and iodomethane is smaller, about attempt by absorb useful component after solution distilled and into The efficiency of its separation, still has the leeway of improvement when row separation.In addition, using second in the method disclosed in patent document 1 Acid is as in the case where lyosoption, and when being distilled by the solution after absorption and separate iodomethane, there are hold inside destilling tower The tendency easily corroded by acetic acid.Further, in the method disclosed in patent document 1, there are the recycling of hydrogen iodide not to fill Point the problem of and due to recycle simultaneously as useful component iodomethane and as remove object component hydrogen iodide and cause The problem of difficult separation and recycling.

Therefore, the purpose of the present invention is to provide the preparation methods that can be realized at least one of following acetic acid: In When recycling iodomethane can be efficiently separated in washing system from the solution comprising iodomethane, being distilled above-mentioned solution not Easily occur destilling tower inside burn into efficiently separated from the exhaust gas of acetic acid preparation process recycling hydrogen iodide and iodomethane, with And fully recycle hydrogen iodide.

Solution to the problem

In order to achieve the above objectives, dissolubility, iodomethane and the absorption for being conceived to hydrogen iodide and iodomethane are molten by the present inventor It the boiling-point difference of agent and absorbs the sequence of hydrogen iodide and iodomethane and has made intensive studies.As a result, having obtained following opinions: It, can be by distillation effectively by iodomethane point by using the solvent big with the boiling-point difference of iodomethane as lyosoption From.In addition, having obtained following opinions: by using the low lyosoption of corrosivity, the corrosion being able to suppress inside destilling tower.Separately Outside, following opinions have been obtained: by using two kinds of different lyosoptions of composition as the lyosoption and suction for absorbing hydrogen iodide The lyosoption for receiving iodomethane can efficiently separate recycling hydrogen iodide and iodomethane from the exhaust gas of acetic acid preparation process.Separately Outside, following opinions have been obtained: by using specific lyosoption, can fully absorb hydrogen iodide.The present invention is based on this A little opinions are simultaneously completed further across research repeatedly.

That is, the present invention provides the preparation method of acetic acid, it include the 1st absorption process and the 2nd in the preparation process of acetic acid Process is absorbed,

It is absorbed in process the described 1st, at least part of the exhaust gas generated in technique is supplied to absorption tower, it is made With the alcohol of the ester comprising the carboxylic acid selected from the alcohol of 2 or more carbon atom number, 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number 1st absorbent of one or more of ester, ether, ketone, water and alkaline aqueous solution liquid contacts and closes the iodate in above-mentioned exhaust gas Object is absorbed in above-mentioned 1st absorbent, thus be separated into the 1st gas that the iodine compound concentration compared with above-mentioned exhaust gas reduces at Point and the 1st solution comprising above-mentioned 1st absorbent and iodine compound；

It is absorbed in process the described 2nd, makes above-mentioned 1st gas componant on absorption tower and comprising selected from 2 or more carbon atom number Alcohol, the ester of carboxylic acid of 3 or more carbon atom number, the ester of the alcohol of carboxylic acid and 2 or more carbon atom number, ether, ketone, water, alkaline aqueous solution, And one or more of acetic acid liquid and composition 2nd absorbent different with above-mentioned 1st absorbent contact and make above-mentioned 1st gas Iodine compound in ingredient is absorbed in above-mentioned 2nd absorbent, so that it is dense to be separated into the iodine compound compared with above-mentioned 1st gas componant Spend the 2nd gas componant reduced and the 2nd solution comprising above-mentioned 2nd absorbent and iodine compound.

In addition, the present invention provides the preparation method of acetic acid comprising:

In the presence of the catalyst system comprising metallic catalyst and iodomethane and acetic acid, methyl acetate, water, make first Pure and mild carbon monoxide reacts in reactive tank and generates the carbonylation process of acetic acid；With

Using more than one evaporator tank and/or destilling tower, it will react mixed obtained in above-mentioned carbonylation process Object is closed to be separated into the stream comprising metallic catalyst, be enriched with the acetic acid stream of acetic acid and low boiling ingredient is more compared with above-mentioned acetic acid stream The separation process of the stream of enrichment,

In the preparation method,

Optionally further comprise: using more than one destilling tower, from by the condensation of the stream of above-mentioned enrichment low boiling ingredient The acetaldehyde that acetaldehyde is separated at least part of obtained condensate liquid is separated off system,

The preparation method includes that the 1st absorption process and the 2nd absorb process,

It is absorbed in process the described 1st, discharge gas, the row from above-mentioned evaporator tank from above-mentioned reactive tank will be selected from Gas, the discharge gas of destilling tower in above-mentioned separation process and the steaming that is separated off from above-mentioned acetaldehyde in system out It evaporates one or more of the discharge gas of tower exhaust gas to supply to absorption tower, makes itself and alcohol, carbon comprising being selected from 2 or more carbon atom number One in the ester of the alcohol of the ester of the carboxylic acid of 3 or more atomicity, carboxylic acid and 2 or more carbon atom number, ether, ketone, water and alkaline aqueous solution Kind or more liquid the 1st absorbent contact and so that the iodine compound in above-mentioned exhaust gas is absorbed in above-mentioned 1st absorbent, to separate For iodine compound concentration reduces compared with above-mentioned exhaust gas the 1st gas componant and comprising above-mentioned 1st absorbent and iodine compound The 1st solution；

It is absorbed in process the described 2nd, makes above-mentioned 1st gas componant on absorption tower and comprising selected from 2 or more carbon atom number Alcohol, the ester of carboxylic acid of 3 or more carbon atom number, the ester of the alcohol of carboxylic acid and 2 or more carbon atom number, ether, ketone, water, alkaline aqueous solution, And one or more of acetic acid liquid and composition 2nd absorbent different with above-mentioned 1st absorbent contact and make above-mentioned 1st gas Iodine compound in ingredient is absorbed in above-mentioned 2nd absorbent, so that it is dense to be separated into the iodine compound compared with above-mentioned 1st gas componant Spend the 2nd gas componant reduced and the 2nd solution comprising above-mentioned 2nd absorbent and iodine compound.

Above-mentioned 1st absorbent preferably comprises water.

Above-mentioned 2nd absorbent preferably comprises acetic acid.

Water concentration in above-mentioned 1st or the 2nd absorbent is preferably 10 mass ppm or more.

Water concentration in one of above-mentioned 1st absorbent and the 2nd absorbent is 10 mass ppm or more, in another one Acetic acid concentration is 10 mass ppm or more.

The preparation method of above-mentioned acetic acid may include: to distill above-mentioned 2nd solution and be separated into enrichment iodomethane The diffusing procedure of the bottom product stream of tower top stream and enrichment acetic acid.The tower top stream of above-mentioned enrichment iodomethane can be recycled to Reaction process.

Carrying out the iodomethane concentration in the feeding liquid of the destilling tower of above-mentioned diffusing procedure is preferably 100 mass ppm or more.

It carries out the concentration of hydrogen iodide in the feeding liquid of the destilling tower of above-mentioned diffusing procedure and is preferably shorter than 100 mass ppm.

In addition, the present invention provides the preparation method of acetic acid comprising:

In the presence of the catalyst system comprising metallic catalyst and iodomethane and acetic acid, methyl acetate, water, make first Pure and mild carbon monoxide reacts in reactive tank and generates the carbonylation process of acetic acid；

The reaction mixture obtained in above-mentioned carbonylation process in evaporator tank is separated into vapor stream and raffinate stream Evaporization process；

Above-mentioned vapor stream is distilled and is separated into the tower top stream of enrichment low boiling ingredient and is enriched with the 1st acetic acid of acetic acid The de- low boiling process of stream；And

Above-mentioned 1st acetic acid stream is distilled and is separated into the tower top stream of enrichment water, 1 acetic acid stream of He Yu more compared to acetic acid The dehydration procedure of 2nd acetic acid stream of enrichment,

In the preparation method,

Optionally further comprise: above-mentioned 2nd acetic acid stream being distilled and is separated into the bottom product for being enriched with high boiling ingredient Stream and acetic acid is more enriched with compared with the acetic acid stream before being distilled the 3rd acetic acid stream take off high boiling process；And/or use one A above destilling tower is separated from least part of condensate liquid obtained from the stream condensation by above-mentioned enrichment low boiling ingredient The acetaldehyde of acetaldehyde is separated off system,

The preparation method includes that the 1st absorption process and the 2nd absorb process,

It is absorbed in process the described 1st, discharge gas, the row from above-mentioned evaporator tank from above-mentioned reactive tank will be selected from The row of gas, the discharge gas of destilling tower in above-mentioned de- low boiling process, destilling tower in above-mentioned dehydration procedure out Out gas, be separated off in system from the above-mentioned discharge gas for taking off the destilling tower in high boiling process and from above-mentioned acetaldehyde One or more of the discharge gas of destilling tower exhaust gas is supplied to absorption tower, make its with comprising selected from 2 or more carbon atom number alcohol, In the ester of the alcohol of the ester of the carboxylic acid of 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number, ether, ketone, water and alkaline aqueous solution 1st absorbent of more than one liquid contacts and the iodine compound in above-mentioned exhaust gas is made to be absorbed in above-mentioned 1st absorbent, thus point From for iodine compound concentration reduces compared with above-mentioned exhaust gas the 1st gas componant and include that above-mentioned 1st absorbent and iodate are closed 1st solution of object；

It is absorbed in process the described 2nd, makes above-mentioned 1st gas componant on absorption tower and comprising selected from 2 or more carbon atom number Alcohol, the ester of carboxylic acid of 3 or more carbon atom number, the ester of the alcohol of carboxylic acid and 2 or more carbon atom number, ether, ketone, water, alkaline aqueous solution, And one or more of acetic acid liquid and composition 2nd absorbent different with above-mentioned 1st absorbent contact and make above-mentioned 1st gas Iodine compound in ingredient is absorbed in above-mentioned 2nd absorbent, so that it is dense to be separated into the iodine compound compared with above-mentioned 1st gas componant Spend the 2nd gas componant reduced and the 2nd solution comprising above-mentioned 2nd absorbent and iodine compound.

Water concentration in above-mentioned 1st or the 2nd absorbent is preferably 10 mass ppm or more.

It is preferred that the water concentration in one of above-mentioned 1st absorbent and the 2nd absorbent is 10 mass ppm or more, another one In acetic acid concentration be 10 mass ppm or more.

Can by above-mentioned 1st recycling solution to be selected from above-mentioned reactive tank, the decanter for being used to store above-mentioned condensate liquid, State the destilling tower in dehydration procedure and more than one device in the above-mentioned destilling tower taken off in high boiling process.

The preparation method of above-mentioned acetic acid may include: to distill above-mentioned 2nd solution and be separated into enrichment iodomethane The diffusing procedure of the bottom product stream of tower top stream and enrichment acetic acid.

Carrying out the iodomethane concentration in the feeding liquid of the destilling tower of above-mentioned diffusing procedure is preferably 100 mass ppm or more.

It carries out the concentration of hydrogen iodide in the feeding liquid of the destilling tower of above-mentioned diffusing procedure and is preferably shorter than 100 mass ppm.

The tower top stream of above-mentioned enrichment iodomethane can be recycled to selected from above-mentioned reaction process, evaporization process and distillation work One or more of sequence process.

The bottom product stream of above-mentioned enrichment acetic acid can be recycled to selected from above-mentioned reaction process, above-mentioned evaporization process, Above-mentioned de- low boiling process, above-mentioned dehydration procedure and above-mentioned more than one process taken off in high boiling process.

Different absorption towers can be used and carry out above-mentioned 1st absorption process and above-mentioned 2nd absorption process.The effect of invention

According to the present invention, the alcohol comprising 2 or more carbon atom number, carbon atom number 3 or more are being used as absorbent The ester of the alcohol of the ester of carboxylic acid, carboxylic acid and 2 or more carbon atom number, ether, ketone, water or alkaline aqueous solution solvent in the case where, for It, can be by distilling iodomethane due to big with the boiling-point difference of iodomethane for the case where having used methanol, methyl acetate It efficiently separates, and/or, for the case where using acetic acid, the corrosion that is able to suppress inside destilling tower.In addition, making In the case where having used the solvent comprising water or alkaline aqueous solution for absorbent, hydrogen iodide can fully be absorbed.Into one Step carries out absorption process by using two kinds of absorbents for forming different, since hydrogen iodide and iodomethane are opposite in two stages It is different in the dissolubility of two kinds of absorbents, therefore respectively, enrichment can be formed in the absorption process for having used a kind of absorbent The solution of one of hydrogen iodide and iodomethane can be formed and above-mentioned solution in the absorption process for having used another absorbent Compared to the solution that the other of hydrogen iodide and iodomethane are more enriched with, so as to efficiently separate recycling hydrogen iodide and iodine first Alkane.

Detailed description of the invention

[Fig. 1] shows the schematic flow diagram of an example of washing system.

[Fig. 2] shows other schematic flow diagrams of washing system.

[Fig. 3] shows another other schematic flow diagrams of washing system.

[Fig. 4] shows the preparation flow figure of an embodiment of acetic acid production systems.

[Fig. 5] shows the schematic flow diagram that acetaldehyde is separated off an example of system.

[Fig. 6] shows the other schematic flow diagrams that acetaldehyde is separated off system.

[Fig. 7] shows another other schematic flow diagrams that acetaldehyde is separated off system.

[Fig. 8] shows another other schematic flow diagrams that acetaldehyde is separated off system.

[Fig. 9] shows the schematic flow diagram of the structure of the washing system used in Examples and Comparative Examples.

Specific embodiment

The preparation method of acetic acid of the invention includes that the 1st absorption process and the 2nd absorb process in the preparation process of acetic acid, It is described 1st absorb process in, at least part of the exhaust gas generated in technique is supplied to absorption tower, make its with comprising choosing From the ester of the alcohol of the alcohol of 2 or more carbon atom number, the ester of the carboxylic acid of 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number, ether, 1st absorbent of one or more of ketone, water and alkaline aqueous solution liquid contacts and absorbs the iodine compound in above-mentioned exhaust gas In above-mentioned 1st absorbent, to be separated into the 1st gas componant, the He Bao that the iodine compound concentration compared with above-mentioned exhaust gas reduces The 1st solution containing above-mentioned 1st absorbent and iodine compound；It is absorbed in process the described 2nd, is inhaling above-mentioned 1st gas componant Receive tower and the ester comprising the carboxylic acid selected from the alcohol of 2 or more carbon atom number, 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number One or more of ester, ether, ketone, water, alkaline aqueous solution and the acetic acid of alcohol liquid and composition is different from above-mentioned 1st absorbent 2nd absorbent contact and so that the iodine compound in above-mentioned 1st gas componant is absorbed in above-mentioned 2nd absorbent, thus be separated into Above-mentioned 1st gas componant compares the 2nd gas componant that iodine compound concentration reduces and comprising above-mentioned 2nd absorbent and iodate Close the 2nd solution of object.1st absorbent and the 2nd absorbent both can only include respectively a kind of above-mentioned solvent, also may include two kinds Above above-mentioned solvent.In addition, the ester of the carboxylic acid of the alcohol of above-mentioned 2 or more carbon atom number, 3 or more carbon atom number, carboxylic acid and carbon are former Ester, ether and the ketone of the alcohol of 2 or more subnumber can be repeated mutually respectively.

In the preparation method of acetic acid of the invention, by the whole exhaust gas generated in the preparation process of acetic acid at least A part supply absorbs process for the 1st and the 2nd to absorption tower.As the exhaust gas for absorbing process for the 1st and the 2nd, can enumerate Such as: the discharge gas of the aftermentioned reactive tank in reaction process, evaporator tank in evaporization process discharge gas, The discharge gas of destilling tower in separation process, the discharge gas of destilling tower being separated off from acetaldehyde in system etc..

1st and the 2nd absorbs process can both carry out respectively on absorption tower, can also more than two absorption towers into Row.For example, will the exhaust gas from more than two techniques for the 1st absorb process in the case where, due in exhaust gas at grouping At differences such as, pressure, therefore more than two absorption towers (such as high pressure absorber and low-pressure absorption tower) can be used, utilize absorption Method carries out the 1st and absorbs process.Process is absorbed alternatively, it is also possible to carry out the 1st and the 2nd on single absorption tower.

As the alcohol of 2 or more above-mentioned carbon atom number in the 1st and the 2nd absorbent, it can be mentioned, for example: ethyl alcohol, 1- propyl alcohol, 2- The unitary such as propyl alcohol, n-butyl alcohol, 2- butanol, isobutanol, the tert-butyl alcohol, cyclohexanol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether Alcohol；Polyalcohols such as ethylene glycol, propylene glycol, diethylene glycol etc..

The ester of carboxylic acid as above-mentioned 3 or more carbon atom number, it can be mentioned, for example: the propionic esters such as methyl propionate, ethyl propionate； The lactates such as methyl lactate, ethyl lactate；The dicarboxyls such as the monocarboxylates such as the butyrates such as methyl butyrate, ethyl butyrate, adipate ester Acid esters etc..

As the ester of above-mentioned carboxylic acid and the alcohol of 2 or more carbon atom number, it can be mentioned, for example: ethyl acetate, ethyl propionate, lactic acid The carboxylic acid, ethyl esters such as ethyl ester, ethyl butyrate；The propyl carboxylates such as propyl acetate；The aklylene glycols second such as ethylene glycol monomethyl ether acetate Acid esters etc..

As above-mentioned ether, it can be mentioned, for example: dimethyl ether, methyl ethyl ether, ether, ethylene glycol monomethyl ether, ethylene glycol list The fatty ethers such as butyl ether；The aromatic ethers such as diphenyl ether；The cyclic ethers such as tetrahydrofuran；The Asias such as ethylene glycol monomethyl ether acetate Alkyl diol ether acetic acid ester etc..

As above-mentioned ketone, it can be mentioned, for example: acetone, methyl ethyl ketone, dimethyl ketone, ethyl methyl ketone, metacetone etc. Aliphatic ketone；The aromatic ketones such as diphenylketone；Ester ring types ketone such as cyclohexanone etc..

It as above-mentioned alkaline aqueous solution, can enumerate: lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium acetate, sodium carbonate, carbon The aqueous solution of alkali metal salt such as sour hydrogen sodium；The alkaline-earth metal saline solution such as magnesium hydroxide, calcium hydroxide, barium hydroxide；Sodium acetate etc. Carboxylic acid salt solution etc..

2nd absorbent is to form different absorbents from the 1st absorbent.For example, can enumerate: not wrapped in one absorbent Though the ingredient contained includes that situation in another one absorbent, two absorbent constituents are identical but at least a kind of ingredient contains Proportional different situation.

As the 1st or the 2nd absorbent, the carboxylic acid of the alcohol, 3 or more carbon atom number that have used 2 or more carbon atom number ester, In the case where the ester of the alcohol of carboxylic acid and 2 or more carbon atom number, ether, ketone, water or alkaline aqueous solution, relative to as absorbent For the case where having used methanol, methyl acetate, since the boiling-point difference of absorbent and iodomethane is big, it will inhaled via the 1st Knock off and the 1st solution obtained from sequence (solution comprising iodomethane and the 1st absorbent) or is absorbed the obtained from process via the 2nd It, can when 2 solution (solution comprising iodomethane and the 2nd absorbent) are distilled and separate iodomethane (aftermentioned diffusing procedure) Efficiently separate iodomethane, and/or, since metal protection is low for acetic acid, relative to as absorbent and For the case where acetic acid, the corrosion that is able to suppress inside destilling tower.Generally, the mixed liquor to acetic acid and iodomethane into In the case where row distillation, since acetic acid is concentrated into tower bottom, so that tower bottom is heated up because of heating sometimes, cause to be drawn by acetic acid The corrosion of the tower bottom risen carries out.In addition, in the case where using water as the 1st or the 2nd absorbent, hydrogen iodide in water molten Xie Xinggao, in addition, hydrogen iodide can also be by other than dissolubility in water in the case where having used alkaline aqueous solution With thus, it is possible to fully absorb hydrogen iodide.Further, by using the 1st and the 2nd different absorbents is formed, both are absorbed Agent carries out absorption process in two stages, since the dissolubility of hydrogen iodide and iodomethane is different in two kinds of absorbents, point Not, the solution of one of enrichment hydrogen iodide and iodomethane, In be will form in the absorption process for having used a kind of absorbent It has used and will form compared with above-mentioned solution the other of hydrogen iodide and iodomethane in the absorption process of another absorbent more The solution of enrichment, so as to which separation and recovery is effectively performed in hydrogen iodide and iodomethane.

1st absorption process is so that the exhaust gas generated in technique is contacted (especially counter current contacting) with the 1st absorbent and make Iodine compound in exhaust gas is absorbed in the 1st absorbent, to be separated into what the iodine compound concentration compared with above-mentioned exhaust gas reduced The process of 1st gas componant and the 1st solution comprising the 1st absorbent and iodine compound.Specifically, exhaust gas is continuously led Enter to the 1st absorption tower for absorbing process is carried out, on the other hand via with exhaust gas supply position compared with positioned at absorption tower internal upper part Route and the 1st absorbent is continuously directed into absorption tower, make the exhaust gas risen in tower and decline the 1st absorbent occur it is inverse Stream contact, so that the iodine compound in exhaust gas be made to be absorbed in the 1st absorbent.In turn, the iodate compared with above-mentioned exhaust gas is separated into close The 1st gas componant that object concentration reduces and the 1st solution comprising iodine compound and the 1st absorbent.It should be noted that the 1st Absorbing process can carry out in a receipts tower, and more than two absorption towers also can be used and carry out.

2nd absorption process is to absorb the 1st gas componant reduced in the 1st absorption process iodine compound concentration with the 2nd Agent contacts (especially counter current contacting), to be separated into the 2nd gas that iodine compound concentration reduces compared with the 1st gas componant The process of ingredient and the 2nd solution comprising the 2nd absorbent and iodine compound.Specifically, carrying out the 2nd suction for absorbing process It receives in tower, continuously leads the 2nd absorbent via the route for being located at absorption tower internal upper part compared with the 1st gas componant supply position Enter to absorption tower, makes the 1st gas componant risen in tower and the 2nd absorbent of decline that counter current contacting occur, to make the 1st gas Iodine compound in body ingredient is absorbed in the 2nd absorbent.In turn, the iodine compound concentration compared with the 1st gas componant is separated into drop The 2nd low gas componant and the 2nd solution comprising iodine compound and the 2nd absorbent.It should be noted that the 2nd absorbs process It can be carried out in a receipts tower, more than two absorption towers also can be used and carry out.The 1st is carried out using more than two absorption towers to absorb In the case where process, process is absorbed for the 2nd after the 1st gas componant from above-mentioned two above absorption tower can be made to collaborate, The 1st gas componant from above-mentioned two above absorption tower can also be respectively fed to one or more absorption tower and supplied Process is absorbed in the 2nd.In addition, the 1st and the 2nd absorption process can carry out on single absorption tower, two or more also can be used Different absorption towers carries out.

As the above-mentioned iodine compound for being absorbed in absorbent in the 1st and the 2nd absorption process, it can enumerate and be present in technique Iodine compound, such as: hydrogen iodide；Idoalkanes such as iodomethane, iodoethane, iodohexane etc..Wherein, it is absorbed as using absorbent Iodine compound, preferably sometimes result in the hydrogen iodide corroded inside destilling tower, as can be used in the reaction process The iodomethane of useful component.Particularly preferably absorbing the iodine compound that process absorbs the 1st is hydrogen iodide, in the 2nd absorption process suction The iodine compound of receipts is iodomethane.In the case where carrying out the 1st and the 2nd absorption process using different absorption towers, if it is possible to Fully absorb hydrogen iodide in the 1st absorption process, then the concentration of hydrogen iodide in the 1st gas componant becomes extremely low, be not easy to cause into Row the 2nd absorbs the corrosion inside the absorption tower of process, which can be used the low material of corrosion resistance (rudimentary material).Into One step absorbs process the 2nd if supply absorbs the concentration of hydrogen iodide in the 1st gas componant of process to the 2nd and extremely reduces In, it does not have hydrogen iodide substantially and is absorbed in the 2nd absorbent, therefore the concentration of hydrogen iodide in the 2nd solution of gained also reduces, rear Rudimentary material can be used in the corrosion being not susceptible to inside destilling tower when distilling 2 solution in the diffusing procedure stated, the destilling tower.It needs It is noted that absorbing absorbed iodine compound in process the 1st and the 2nd respectively can be only one kind, or two kinds More than.

Therefore, from the viewpoint of the absorbability of hydrogen iodide is high, the 1st absorbent preferably comprises water or alkaline aqueous solution.Separately Outside, from the viewpoint of the absorbability of iodomethane is high, the 2nd absorbent preferably comprises alcohol, carbon atom selected from 2 or more carbon atom number One or more of ester, ether, ketone and the acetic acid of alcohol of the ester of the carboxylic acid of 3 or more number, carboxylic acid and 2 or more carbon atom number solvent.This It in the case of kind, is absorbed in process the 1st, can fully recycle hydrogen iodide from exhaust gas using the 1st absorbent, also, the 1st Iodomethane will not be absorbed substantially in absorbent, but can the 2nd absorb process in using the 2nd absorbent by iodomethane fully Recycling, therefore recycling hydrogen iodide and iodomethane can be efficiently separated.As the 2nd absorbent, wherein from iodomethane is being followed again It prevents from being mixed into system from the perspective of unwanted ingredient when ring to reaction system or purification system, preferably comprises acetic acid.In In the case where having used such 1st and the 2nd absorbent, it is able to selectively absorb recycling/removing in process the 1st Hydrogen iodide absorbs recycling/removing iodomethane in process the 2nd, therefore can recycle and contain substantially no unwanted hydrogen iodide Iodomethane becomes easy in the recycling of reactive tank.In addition, being carried out to the acetic acid for being used as absorbent in the 2nd absorption process When distilling and being purified, it is able to suppress the corrosion for carrying out the destilling tower of the distillation.

1st and the 2nd absorbent may include the ingredient other than aforesaid liquid respectively.It can be mentioned, for example: methanol, methyl acetate Etc. the ester of the carboxylic acid of carbon atom numbers 1 or 2, the methyl ester of the carboxylic acid of 3 or more carbon atom number, acetic acid (the case where 1 absorbent) or Solvent other than the aforesaid liquids such as the carboxylic acids such as formic acid；Other impurity etc. for using or being formed in the preparation process of acetic acid.

Ester, carboxylic acid and the carbon of the carboxylic acid of the alcohol selected from 2 or more carbon atom number, 3 or more carbon atom number in 1st absorbent are former One or more of the ester of the alcohol of 2 or more subnumber, ether, ketone and water (also including the case where using alkaline aqueous solution) solvent it is dense Degree for example, 10 mass ppm or more, preferably 20 mass ppm or more, more preferably 50 mass ppm or more, it is more preferably 100 mass ppm or more, particularly preferably 200 mass ppm or more, or 300 mass ppm or more, 400 mass ppm with Upper, 500 mass ppm or more, 1000 mass ppm or more, 1 mass % or more, 5 mass % or more, 10 mass % or more, 20 matter Measure % or more, 30 mass % or more, 40 mass % or more, 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 Quality % or more, 90 mass % or more.It in addition, the upper limit of above-mentioned concentration is 100 mass %, but may be 99.999 matter Measure %, 99.99 mass %, 99.9 mass %, 99.5 mass %, 99 mass %, 98 mass %.In addition, the water in the 1st absorbent Concentration can also be within the above range.

Ester, carboxylic acid and the carbon of the carboxylic acid of the alcohol selected from 2 or more carbon atom number, 3 or more carbon atom number in 2nd absorbent are former One or more of ester, ether, ketone, water (also including the case where using alkaline aqueous solution) and the acetic acid of the alcohol of 2 or more subnumber solvent Concentration be, for example, 10 mass ppm or more, preferably 20 mass ppm or more, more preferably 50 mass ppm or more, further it is excellent It is selected as 100 mass ppm or more, particularly preferably 200 mass ppm or more, or 300 mass ppm or more, 400 mass ppm Above, 500 mass ppm or more, 1000 mass ppm or more, 1 mass % or more, 5 mass % or more, 10 mass % or more, 20 matter Measure % or more, 30 mass % or more, 40 mass % or more, 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 Quality % or more, 90 mass % or more.It in addition, the upper limit of above-mentioned concentration is 100 mass %, but may be 99.999 matter Measure %, 99.99 mass %, 99.9 mass %, 99.5 mass %, 99 mass %, 98 mass %.In particularly preferred 2nd absorbent The alcohol selected from 2 or more carbon atom number, the ester of carboxylic acid of 3 or more carbon atom number, carboxylic acid and 2 or more carbon atom number alcohol ester, The concentration (especially acetic acid concentration) of one or more of ether, ketone and acetic acid solvent is within the above range.In addition, the 2nd absorbent In acetic acid concentration can be within the above range.

Water concentration in one of 1st absorbent and the 2nd absorbent is, for example, 10 mass ppm or more, preferably 20 matter Measure ppm or more, more preferably 50 mass ppm or more, further preferably 100 mass ppm or more, particularly preferably 200 mass Ppm or more, or 300 mass ppm or more, 400 mass ppm or more, 500 mass ppm or more, 1000 mass ppm or more, 1 mass % or more, 1000 mass ppm or more, 1 mass % or more, 5 mass % or more, 10 mass % or more, 20 mass % with Upper, 30 mass % or more, 40 mass % or more, 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 mass % Above, 90 mass % or more.In addition, the upper limit of above-mentioned water concentration be 100 mass %, but may be 99.999 mass %, 99.99 mass %, 99.9 mass %, 99.5 mass %, 99 mass %, 98 mass %.

Hydrogen iodide include molecular state hydrogen iodide and at least part polarizable medium (generally at least include water Jie Matter) in both dissociation hydroiodic acid in the case where ionization has occurred, the two has interchangeability.In the present specification, iodine Change hydrogen concentration can use potentiometric titration and find out, and also can use and is found out and subtracting from all ionic iodide It cuts algorithm and finds out.

In potentiometric titration, it can be found out by acid-base titration, using potentiometric titration end-point.In particular, hydrogen iodide is dense Degree can be titrated to potentiometric titration end-point by using the lithium acetate solution etc. of standard and find out.Cut algorithm be by from be present in examination The related iodine of measurement being deduced with corrosion metal or other non-hydrogen cations is subtracted in the ionic iodide of whole in sample The concentration of compound and carry out the method for asking calculation.

It is, for example, 0.01 mass ppm or more using the concentration of hydrogen iodide in the 1st solution found out that cuts algorithm, or 0.1 mass ppm or more, 1 mass ppm or more, 10 mass ppm or more, 50 mass ppm or more, 100 mass ppm or more, 200 matter Measure ppm or more, 300 mass ppm or more, 400 mass ppm or more, 500 mass ppm or more, 600 mass ppm or more, 700 mass Ppm or more, 800 mass ppm or more, 900 mass ppm or more, 1000 mass ppm or more, 2000 mass ppm or more, 3000 matter Measure ppm or more, 4000 mass ppm or more, 5000 mass ppm or more, 6000 mass ppm or more, 7000 mass ppm or more, 8000 mass ppm or more, 9000 mass ppm or more, 1 mass % or more.Above-mentioned concentration of hydrogen iodide be, for example, 10 mass % hereinafter, Or 5 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 5000 mass ppm or less, 3000 Quality ppm or less.

The concentration of hydrogen iodide in the 1st solution found out using potentiometric titration is, for example, 0.01 mass ppm or more, can also be with For 0.1 mass ppm or more, 1 mass ppm or more, 10 mass ppm or more, 50 mass ppm or more, 100 mass ppm or more, 200 Quality ppm or more, 300 mass ppm or more, 400 mass ppm or more, 500 mass ppm or more, 600 mass ppm or more, 700 matter Measure ppm or more, 800 mass ppm or more, 900 mass ppm or more, 1000 mass ppm or more, 2000 mass ppm or more, 3000 Quality ppm or more, 4000 mass ppm or more, 5000 mass ppm or more, 6000 mass ppm or more, 7000 mass ppm or more, 8000 mass ppm or more, 9000 mass ppm or more, 1 mass % or more.Above-mentioned concentration of hydrogen iodide be, for example, 5 mass % or less, Preferably 2 mass % or less.Above-mentioned concentration of hydrogen iodide is, for example, 10 mass % or less, or 5 mass % or less, 3 matter Measure % or less, 2 mass % or less, 1 mass % or less, 5000 mass ppm or less, 3000 mass ppm or less.

Iodomethane concentration in 1st solution is, for example, 30 mass % or less, or 25 mass % or less, 20 mass % Below, 15 mass % or less, 10 mass % or less, 7 mass % or less, 5 mass % or less, 4 mass % or less, 3 mass % with Under, 2 mass % or less, 1 mass % or less, 5000 mass ppm or less, 2000 mass ppm or less, 1000 mass ppm or less.On State iodomethane concentration be, for example, 10 mass ppm or more (such as 50 mass ppm or more), preferably 100 mass ppm or more (such as 500 mass ppm or more), more preferably 1000 mass ppm or more (such as 2000 mass ppm or more).

It should be noted that in the case where absorbing process with multiple 1, above-mentioned each ingredient in the 1st solution it is dense Degree is the concentration for absorbing above-mentioned each ingredient in all the 1st solution that separation in process obtains above-mentioned multiple 1.

The concentration of hydrogen iodide in the 1st solution, example are preferably shorter than using the concentration of hydrogen iodide in the 2nd solution found out that cuts algorithm For example 5 mass % or less, or 4 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 5000 Quality ppm or less, 3000 mass ppm or less, 2000 mass ppm or less, 1000 mass ppm or less, 700 mass ppm or less, 500 mass ppm or less, 300 mass ppm or less, 200 mass ppm or less, 100 mass ppm or less, it is lower than 100 mass ppm, 50 Quality ppm or less, 30 mass ppm or less, 20 mass ppm or less, 10 mass ppm or less, 5 mass ppm or less, 3 mass ppm with Under, 2 mass ppm or less, 1 mass ppm or less.Above-mentioned concentration of hydrogen iodide is, for example, 0.0001 mass ppm or more, or 0.001 mass ppm or more, 0.01 mass ppm or more, 0.1 mass ppm or more, 0.5 mass ppm or more.

The hydrogen iodide that the concentration of hydrogen iodide in the 2nd solution found out using potentiometric titration is preferably shorter than in the 1st solution is dense Degree, for example, 5 mass % or less, or 4 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 5000 mass ppm or less, 3000 mass ppm or less, 2000 mass ppm or less, 1000 mass ppm or less, 700 mass ppm with Under, 500 mass ppm or less, 300 mass ppm or less, 200 mass ppm or less, 100 mass ppm or less, be lower than 100 mass Ppm, 50 mass ppm or less, 30 mass ppm or less, 20 mass ppm or less, 10 mass ppm or less, 5 mass ppm or less, 3 matter Measure ppm or less, 2 mass ppm or less, 1 mass ppm or less.Above-mentioned concentration of hydrogen iodide is, for example, 0.0001 mass ppm or more, It can be 0.001 mass ppm or more, 0.01 mass ppm or more, 0.1 mass ppm or more, 0.5 mass ppm or more.

Iodomethane concentration in 2nd solution is preferably higher than the iodomethane concentration in the 1st solution, for example, 1 mass ppm with On, or 10 mass ppm or more, 100 mass ppm or more, 1000 mass ppm or more, 5000 mass ppm or more, 1 matter Measure % or more.Above-mentioned iodomethane concentration be, for example, 20 mass % or less (such as 15 mass % or less), preferably 10 mass % with Under (such as 8 mass % or less).

It should be noted that in the case where absorbing process with multiple 2, above-mentioned each ingredient in the 2nd solution it is dense Degree is the concentration for absorbing above-mentioned each ingredient in all the 2nd solution that separation in process obtains above-mentioned multiple 2.

The preparation method of acetic acid of the invention can have: will the 1st absorb process obtained in the 1st solution and/or The distillation process (diffusing procedure) that 2nd solution obtained in 2nd absorption process is distilled.In diffusing procedure, by the 1st and/ Or the 2nd solution distilled and be separated into low boiling ingredient is more enriched with compared with the 1st and/or the 2nd absorbent tower top stream and enrichment The bottom product stream of 1st and/or the 2nd absorbent.In the case where with diffusing procedure, useful component and enrichment can be separated into The bottom product stream of 1st and/or the 2nd absorbent, therefore useful component can be recycled to reactive tank, evaporator tank, destilling tower Deng, using the absorbent isolated as the 1st and/or the 2nd absorption process absorbent recycle, economy is excellent.

The iodomethane concentration being diffused in the feeding liquid of the destilling tower of process is, for example, 1 mass ppm or more, or 10 mass ppm or more, 100 mass ppm or more, 1000 mass ppm or more, 5000 mass ppm or more, 1 mass % or more.It is above-mentioned Iodomethane concentration is, for example, 20 mass % or less (such as 15 mass % or less), preferably 10 mass % or less (such as 8 mass % Below).

It is, for example, 5 matter using the concentration of hydrogen iodide in the feeding liquid for the destilling tower for being diffused process found out that cuts algorithm Measure % or less, or 4 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 5000 mass ppm Below, 3000 mass ppm or less, 2000 mass ppm or less, 1000 mass ppm or less, 700 mass ppm or less, 500 mass Ppm or less, 300 mass ppm or less, 200 mass ppm or less, 100 mass ppm or less, it is lower than 100 mass ppm, 50 mass ppm Below, 30 mass ppm or less, 20 mass ppm or less, 10 mass ppm or less, 5 mass ppm or less, 3 mass ppm or less, 2 matter Measure ppm or less, 1 mass ppm or less.Above-mentioned concentration of hydrogen iodide is, for example, 0.0001 mass ppm or more, or 0.001 matter Measure ppm or more, 0.01 mass ppm or more, 0.1 mass ppm or more, 0.5 mass ppm or more, 1 mass ppm or more.

Concentration of hydrogen iodide in the feeding liquid of the destilling tower for being diffused process found out using potentiometric titration is, for example, 5 Quality % or less, or 4 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 5000 mass Ppm or less, 3000 mass ppm or less, 2000 mass ppm or less, 1000 mass ppm or less, 700 mass ppm or less, 500 matter It measures ppm or less, 300 mass ppm or less, 200 mass ppm or less, 100 mass ppm or less, be lower than 100 mass ppm, 50 mass Ppm or less, 30 mass ppm or less, 20 mass ppm or less, 10 mass ppm or less, 5 mass ppm or less, 3 mass ppm or less, 2 Quality ppm or less, 1 mass ppm or less.Above-mentioned concentration of hydrogen iodide is, for example, 0.0001 mass ppm or more, or 0.001 Quality ppm or more, 0.01 mass ppm or more, 0.1 mass ppm or more, 0.5 mass ppm or more, 1 mass ppm or more.

As the low boiling ingredient being concentrated into tower top stream obtained in diffusing procedure separation, can enumerate: iodine compound (iodine Methane, hydrogen iodide etc.), water, methyl acetate, dimethyl ether, methanol, acetaldehyde and formic acid etc..Above-mentioned tower top stream includes that iodomethane etc. has In the case where with ingredient, it will can be recycled at least partially reactive tank (reaction process).By being recycled to reactive tank, energy Enough recyclings that useful component is realized in reaction process, economy are excellent.

It should be noted that being that aftermentioned come from makes to come autospasy low boiling for storing by the exhaust gas for the 1st absorption process In the case where the exhaust of the decanter of condensate liquid obtained from the tower top stream condensation of process, sometimes in the tower top from diffusing procedure It can more include acetaldehyde in stream.Therefore, for the above-mentioned tower top stream from diffusing procedure, acetaldehyde can be supplied in and be separated off System, can also be after acetaldehyde be separated off system progress acetaldehyde removing through being recycled to reactive tank by decanter.In addition, can It (takes off low boiling process above-mentioned tower top stream is recycled to the distillation process for being located at downstream compared to evaporization process, dehydration procedure, take off High boiling process etc.).

Iodomethane concentration in above-mentioned tower top stream from diffusing procedure is, for example, 5 mass % or more, or 10 matter Measure % or more, 20 mass % or more, 30 mass % or more, 40 mass % or more, 50 mass % or more, 60 mass % or more, 70 Quality % or more, 80 mass % or more.The upper limit of above-mentioned iodomethane concentration is, for example, 99.9 mass % (such as 99 mass %), excellent It is selected as 98 mass % (such as 95 mass %), is more preferably 93 mass % (90 mass %), or 80 mass %, 70 matter Measure %, 60 mass %, 50 mass %, 45 mass %.

For the bottom product stream from destilling tower tower bottom obtained in diffusing procedure separation, will can connect at least partially It is discharged to outside system continuously, will can also be recycled at least partially the 1st and/or the 2nd absorption tower.Furthermore it is possible to by above-mentioned tower At least part of kettle raffinate stream be recycled to reaction process, evaporization process, compared with evaporization process be located at downstream purifying work Sequence (distillation process) etc..

Hereinafter, being said for an embodiment of the washing system for having the 1st and the 2nd absorption process of the invention It is bright.Fig. 1 is to show an example of the schematic flow diagram of an embodiment of the washing system in the present invention.The washing system 8 Have: absorption tower 81, absorption tower 82, absorption tower 83 and destilling tower 84.In the preparation method of the acetic acid of present embodiment, point Not, absorption tower 81,82 respectively in carry out the 1st absorb process, in absorption tower 83 carry out the 2nd absorb process, in destilling tower Process is diffused in 84.

Absorption tower 81 is for absorb from the high pressure gas in exhaust gas and recycle the 1st of iodine compound absorbing process Unit (high pressure absorber).1st absorption process is to contact high pressure gas with the 1st absorbent and make the iodine in high pressure gas Compound is absorbed in the 1st absorbent, to be separated into the 1st gas that the iodine compound concentration compared with above-mentioned high pressure gas reduces The process of ingredient and the 1st solution comprising the 1st absorbent and iodine compound.

Specifically, making high pressure gas continuously import absorption tower 81 via route 58 (high pressure gas supply lines), separately On the one hand, make the 1st via route 59 (the 1st absorbent supply lines) superposed compared with the importing position of high pressure gas Absorbent continuously imports absorption tower 81, so that the high pressure gas risen in tower and the 1st absorbent of decline occur adverse current and connect Touching, so that the intracorporal iodine compound of high pressure gas be made to be absorbed in the 1st absorbent.In turn, it is separated into the iodine compared with above-mentioned high pressure gas The 1st gas componant that compound concentration reduces and the 1st solution comprising iodine compound and the 1st absorbent, respectively, from suction 81 tower top of tower is received to obtain the 1st gas componant via route 60, obtain the 1st solution from 81 tower bottom of absorption tower via route 61.

As above-mentioned high pressure gas, for example, can autoreaction slot in future (or reaction process) discharge gas, i.e. from reaction The discharge gas of slot discharge is directly supplied via route 58 to absorption tower 81, the discharge gas benefit that can also will be discharged from reactive tank Noncondensable gas after isolating condensation ingredient with condenser is via the supply of route 58 to absorption tower 81.Supply to absorption tower 81 it The temperature of the 1st preceding absorbent is, for example, 1~120 DEG C, is that not will lead in the range of the 1st absorbent freezes, do not boil Temperature.

Absorption tower 81 includes the rectifying columns such as column plate tower and packed column.Filler in packed column can be regular filler, Any filler in irregular filler.In the case where column plate tower, theoretical tray is, for example, 1~100 layer.Tower internal pressure Power is, for example, atmospheric pressure~5MPaG (gauge pressure), below the pressure usually in reactive tank.Temperature is, for example, 1~120 DEG C of left side in tower It is right.

Absorption tower 82 is the 1st absorption process that iodine compound is absorbed and recycled for carrying out the low-pressure gas from exhaust gas Unit (low-pressure absorption tower).1st absorption process is to contact low-pressure gas with the 1st absorbent and make the iodate in low-pressure gas Close object and be absorbed in the 1st absorbent, thus be separated into the 1st gas that the iodine compound concentration compared with above-mentioned low-pressure gas reduces at Point and the 1st solution comprising the 1st absorbent and iodine compound process.

Specifically, making low-pressure gas continuously import absorption tower 82 via route 62 (low-pressure gas supply lines), separately On the one hand, make the 1st via route 63 (the 1st absorbent supply lines) superposed compared with the importing position of low-pressure gas Absorbent continuously imports absorption tower 82, so that the low-pressure gas risen in tower and the 1st absorbent of decline occur adverse current and connect Touching, so that the intracorporal iodine compound of low pressure gas be made to be absorbed in the 1st absorbent.In turn, it is separated into the iodine compared with above-mentioned low-pressure gas The 1st gas componant that compound concentration reduces and the 1st solution comprising iodine compound and the 1st absorbent, respectively, from suction 82 tower top of tower is received to obtain the 1st gas componant via route 64, obtain the 1st solution from 82 tower bottom of absorption tower via route 65.

It as above-mentioned low-pressure gas, can enumerate: come from the discharge gas of evaporator tank (or evaporization process), carry out autospasy low boiling tower The discharge gas of (or de- low boiling process), the tower top stream condensation from the enrichment low boiling ingredient for storing autospasy low boiling tower in future Obtained from condensate liquid decanter discharge gas, the discharge gas from dehydrating tower (or dehydration procedure), to carry out autospasy high boiling The discharge gas of tower (or taking off high boiling process).These discharge gases can directly be supplied via route 62 to absorption tower 82, It can be supplied via route 62 to absorption tower 82 in the form of isolating the noncondensable gas after condensation ingredient using condenser. Supply the temperature phase to the temperature of the 1st absorbent before absorption tower 82, with supply to the 1st absorbent before absorption tower 81 Together.

Absorption tower 82 includes the rectifying columns such as column plate tower and packed column.Filler in packed column can be regular filler, Any filler in irregular filler.In the case where column plate tower, theoretical tray is, for example, 1~100 layer.Tower internal pressure Power is, for example, atmospheric pressure~5MPaG, below the pressure usually in reactive tank.Temperature is, for example, 1~120 DEG C or so in tower.

The 1st gas componant (route 60) from 81 tower top of absorption tower and the 1st gas componant from 82 tower top of absorption tower (route 64) interflow is simultaneously supplied to the absorption tower 83 for carrying out the 2nd absorption process via route 69.On the other hand, absorption tower is come from 1st solution (route 61) of 81 tower bottom and from 82 tower bottom of absorption tower the 1st solution (route 65) interflow after part of it via Route 66 is continually or intermittently expelled to outside system, also, continually or intermittently supplies new the 1st via route 67 Absorbent is divided into route 59,63 via route 68 and behind and is recycled to absorption tower 81 respectively, and 82, and absorbed as the 1st The 1st absorbent in process is reused.It should be noted that can not recycle for the 1st solution and body is all discharged System is outer, and 1st absorbent new to the supply of absorption tower 81,82.Furthermore it is possible to by least part of the 1st solution (such as via Route 66 and the 1st solution being discharged outside system) it is recycled to reactive tank, evaporator tank, the destilling tower for carrying out distillation process.Example Such as, in the case where the 1st absorbent includes water, hydrogen iodide is effectively absorbed using the 1st absorbent, therefore can be by the 1st solution Almost all be recycled to the 1st absorption tower and recycled as the 1st absorbent, the case where hydrogen iodide have passed through concentration Under, part of it is recycled to reactive tank.This is because, water can be because of the conversion reaction with carbon monoxide in reactive tank (H₂O+CO→H₂+CO₂) and be consumed.It should be noted that in the case where the 1st solution includes a large amount of water, sometimes in reactive tank In will not be sufficiently consumed, therefore, can replace the recycling to reactive tank or while recycling to reactive tank, then follow Water phase, dehydrating tower, de- high boiling tower in ring to above-mentioned decanter.In this case, the water phase in such as decanter, dehydrating tower Tower top takes off high boiling column overhead by concentration, and part of it is recycled to reactive tank, other parts are expelled to outside system.Separately Outside, it in Fig. 1, is illustrated in absorption tower 81,82 using the example of identical 1st absorbent, but also can be used Different the 1st absorbent and each 1st absorbent is recycled, outside discharge system, recycling etc..

Absorption tower 83 is for absorb from the 1st gas componant being discharged by the 1st absorption process and recycle iodate closing The 2nd of object absorbs the unit (usually low-pressure absorption tower) of process.2nd absorption process is to absorb the 1st gas componant with the 2nd Agent contacts and the iodine compound in the 1st gas componant is made to be absorbed in the 2nd absorbent, to be separated into and above-mentioned 1st gas componant Compared to the process for the 2nd gas componant and the 2nd solution comprising the 2nd absorbent and iodine compound that iodine compound concentration reduces.

Specifically, make the 1st gas componant continuously import absorption tower 83 via route 69, on the other hand, via with the 1st The importing position of gas componant makes the 2nd absorbent continuously compared to superposed route 70 (the 2nd absorbent supply lines) Absorption tower 83 is imported, so that counter current contacting occurs for the 1st gas componant risen in tower and the 2nd absorbent of decline, to make Iodine compound in 1st gas componant is absorbed in the 2nd absorbent.In turn, the iodate compared with above-mentioned 1st gas componant is separated into close The 2nd gas componant that object concentration reduces and the 2nd solution comprising iodine compound and the 2nd absorbent, respectively, from absorption tower 83 tower tops obtain the 2nd gas componant via route 71, obtain the 2nd solution from 83 tower bottom of absorption tower via route 72.Supply The temperature of the 2nd absorbent before to absorption tower 83 is, for example, 1~120 DEG C, is that not will lead to the 2nd absorbent to freeze, do not occur Temperature in the range of boiling.

The 2nd gas componant (route 71) from 83 tower top of absorption tower is to capture and eliminate the gas after useful component, It will be discarded.It should be noted that can be used as the aftermentioned bottom for being directed into evaporator tank 2 or residual from the gas that route 71 is discharged The source CO of liquid stream recirculation circuit 18,19 and be used.On the other hand, the 2nd solution (route from 83 tower bottom of absorption tower 72) it is supplied to destilling tower 84.

Absorption tower 83 includes the rectifying columns such as column plate tower and packed column.Filler in packed column can be regular filler, Any filler in irregular filler.In the case where column plate tower, theoretical tray is, for example, 1~100 layer.Tower internal pressure Power is, for example, atmospheric pressure~5MPaG, below the pressure usually in reactive tank.Temperature is, for example, 1~120 DEG C or so in tower.

Destilling tower 84 is the unit for being diffused process.Diffusing procedure in present embodiment be by the 2nd solution into Row distills and is separated into the bottom product stream of the 2nd absorbent of tower top stream and enrichment of enrichment useful component (especially iodomethane) Process.From the top of tower of destilling tower 84, the steam as tower top stream is continuously extracted to route 73.From the tower bottom of destilling tower 84 Portion, bottom product are continuously extracted to route 74.84b is reboiler.

More specifically, the 2nd solution for continuously being imported destilling tower 84 is subjected to distillation processing and is separated into and is enriched with With the bottom product of the 2nd absorbent of tower top stream and enrichment of ingredient (especially iodomethane).Destilling tower 84 includes such as column plate tower And the rectifying columns such as packed column.The tower top stream of destilling tower 84 is imported into condenser 84a via route 73.Condenser 84a pass through by Tower top stream from destilling tower 84 is cooling and makes its partial condensation, to be divided into the condensation gentle body ingredient of ingredient.Ingredient will be condensed A part be back to destilling tower 84, distillate other parts from route 73b.It should be noted that showing in Fig. 1 will condense Ingredient is back to the example of destilling tower 84, all distillates its from route 73b however, you can also not be flowed back.Pass through condenser The noncondensable gas that 84a is not condensed can be circulated to absorption tower 82 after collaborating to route 62 via route 73a, can also To be discarded, it is up to alternatively, can also be recirculated to for making to carry out the steamings such as autospasy low boiling tower, dehydrating tower, de- high boiling tower Before the condenser of tower top stream condensation for evaporating the tower top of tower.It, can be then in benefit for have passed through the noncondensable gas of recycling It is eliminated with condenser point after be condensed into, is recycled to absorption tower 82 from route 62 again.

The tower top stream (route 73) of enrichment useful component (especially iodomethane) from 84 tower top of destilling tower can be followed again Ring to reactive tank, evaporator tank, compared with evaporator tank be located at downstream destilling tower.By being recycled to reactive tank, can react Process realizes that the recycling of useful component (especially iodomethane), economy are excellent.It is next by the exhaust gas of process is absorbed for the 1st In the case where the exhaust of decanter, the tower top stream of above-mentioned enrichment useful component is compared with the 2nd absorbent, and low boiling ingredient is by into one Step concentration, therefore sometimes more include acetaldehyde.Therefore, it for the tower top stream of above-mentioned enrichment useful component, can supply to second Aldehyde is separated off system, can also be separated off after system carries out acetaldehyde removing in acetaldehyde and is recycled to reaction by decanter Slot.On the other hand, for the bottom product stream (route 74) from 84 tower bottom of destilling tower, part of it via route 75 and by It is continually or intermittently discharged to outside system, also, continually or intermittently supplies the 2nd new absorbent via route 76, It is recycled to absorption tower 83 via route 70, and is reused as the 2nd absorbent in the 2nd absorption process.It should be noted that For the 2nd solution, it can not recycle outside its whole discharge system, and supply the 2nd new absorbent to absorption tower 83.Separately Outside, at least part (such as the 2nd solution being discharged outside system via route 75) of the 2nd solution can be recycled to instead Answer slot, evaporator tank, compared with evaporator tank positioned at the destilling tower (evaporator tank, de- low boiling tower, dehydrating tower, de- high boiling tower etc.) in downstream Deng.

Using column plate tower as destilling tower 84, though the composition dependent on the 2nd solution distilled, right Its theoretical tray is, for example, 1~50 layer in the acetic acid the case where, and reflux ratio is, for example, 0~3000 according to theoretical cam curve.In The inside of destilling tower 84, tower top pressure for example may be set to 1~500kPaG, and tower bottom pressure may be set to be higher than tower top pressure, example Such as 10~700kPaG.In the inside of destilling tower 84, tower top temperature may be set to such as less than set the 2nd suction under tower top pressure Such as 40~130 DEG C of temperature for receiving the boiling point of agent, column bottom temperature may be set to the boiling point for for example setting the acetic acid under tower bottom pressure Above 118~165 DEG C of the temperature (preferably 120~160 DEG C).

Fig. 2 is to show the schematic flow diagram of the another embodiment for the washing system for absorbing process with the 1st and the 2nd An example.In this embodiment, the 1st only is carried out on absorption tower 81 absorb process, the 1st gas componant warp of 81 tower top of self-absorption in future tower It is supplied by route 60 to the 2nd absorption tower 83 for absorbing process is carried out, the 1st solution is extracted from tower bottom via route 61, by it A part is expelled to outside system (route 66), and 1st absorbent (route 67) new to the supply of the 1st solution, via route 59 Absorption tower 81 is back to again as the 1st absorbent to be recycled.In addition to this, identical as the example of Fig. 1.

Fig. 3 is to show the signal stream of other another embodiments of the washing system for absorbing process with the 1st and the 2nd An example of journey figure.In this embodiment, the 1st and the 2nd is carried out on single absorption tower 85 absorb process.Specifically, absorbing work the 1st In sequence, exhaust gas in technique is continuously imported absorption tower 85 via route 77 (exhaust gas supply lines), on the other hand, via with The importing position of exhaust gas imports the 1st absorbent continuously compared to superposed route 78 (the 1st absorbent supply lines) Absorption tower 85, so that counter current contacting occurs for the exhaust gas risen in tower and the 1st absorbent of decline, to make the iodate in exhaust gas It closes object and is absorbed in the 1st absorbent.In turn, be separated into the 1st gas componant that the iodine compound concentration compared with above-mentioned exhaust gas reduces, With the 1st solution comprising iodine compound and the 1st absorbent, the 1st gas componant is further up in absorption tower 85, the 1st solution It is discharged from 85 tower bottom of absorption tower via route 79.It is absorbed in process the 2nd, the 1st gas componant is opposite in absorption tower 85 It is further up for the importing position of the 1st absorbent, on the other hand, connect via the route 86 near 85 tower top of absorption tower The 2nd absorbent is imported continuously, so that counter current contacting occurs for the 1st gas componant risen in tower and the 2nd absorbent of decline, from And the iodine compound in the 1st gas componant is made to be absorbed in the 2nd absorbent.In turn, the iodate compared with the 1st gas componant is separated into close The 2nd gas componant that object concentration reduces and the 2nd solution comprising iodine compound and the 2nd absorbent, the 2nd gas componant is from suction 85 tower top of tower is received to be extracted, the liquid that the 2nd solution is fallen in the importing position that can be received from the 2nd absorbent via route 89 Unit (chimney tray etc.) 87 it is captured, and be extracted from route 88.2nd solution of self-absorption in future tower 85 is via route 88 supplies extract the 1st solution from tower bottom via route 79, part of it are expelled to the destilling tower 84 for being diffused process System is outer (route 90), and 1st absorbent (route 90 ') new to the supply of the 1st solution, absorbs via route 78 as the 1st Agent is recycled to absorption tower 85 and is recycled.In addition, for the bottom product stream (route 74) from 84 tower bottom of destilling tower, A part is continually or intermittently discharged to outside system via route 75, also, via route 76 and continuously or interval The 2nd new absorbent of ground supply is recycled to absorption tower 85 via route 86, and absorbs the 2nd absorbent quilt in process as the 2nd It recycles.In addition to this, identical as the example of Fig. 1.That is, the 2nd solution from absorption tower 85 is supplied to diffusing procedure, but It can be by each position in the 1st and/or the 2nd recycling solution to technique.

In the preparation method of acetic acid of the invention, the preparation process of acetic acid be can have: keep methanol anti-with carbon monoxide Answer and generate the carbonylation process of acetic acid；With use more than one evaporator tank and/or destilling tower, will be in above-mentioned carbonylation Reaction mixture obtained in reaction process be separated into the stream comprising metallic catalyst, be enriched with acetic acid acetic acid stream and with it is upper State separation process of the acetic acid stream compared to the stream that low boiling ingredient is more enriched with.Above-mentioned separation process preferably has for example: will be above-mentioned Reaction mixture obtained in carbonylation process is separated into the evaporization process of vapor stream and raffinate stream in evaporator tank；With will be upper Vapor stream is stated to be distilled and be separated into the tower top stream of enrichment low boiling ingredient and be enriched with the de- low boiling work of the 1st acetic acid stream of acetic acid Sequence.In addition, above-mentioned separation process also can have: above-mentioned 1st acetic acid stream is distilled and be separated into enrichment water tower top stream, With the dehydration procedure for the 2nd acetic acid stream that acetic acid is more enriched with compared with the 1st acetic acid stream.

It should be noted that can replace above-mentioned evaporization process and de- low boiling process in above-mentioned separation process and have and incite somebody to action The reaction mixture obtained in above-mentioned carbonylation process is separated into the above-mentioned stream comprising catalyst, above-mentioned enrichment low boiling The process (evaporating de- low boiling process) of 1st acetic acid stream of the tower top stream and enrichment acetic acid of ingredient.In addition, in above-mentioned separation process, It can replace above-mentioned de- low boiling process and dehydration procedure and include the de- low boiling process for the function of being also equipped with above-mentioned dehydration procedure (so-called de- low boiling dehydration procedure), that is, above-mentioned vapor stream is distilled and be separated into enrichment low boiling ingredient tower top stream and The process for being dehydrated to the acetic acid stream of the water concentration same with above-mentioned 2nd acetic acid stream.As a result, above-mentioned evaporation take off low boiling process can be with It is the process (evaporating de- low boiling dehydration procedure) for the function of being also equipped with above-mentioned dehydration procedure.It is de- by de- low boiling dehydration procedure and evaporation The acetic acid stream for the enrichment acetic acid that low boiling dehydration procedure obtains is suitable with above-mentioned 2nd acetic acid stream.

In addition, the preparation method of acetic acid of the invention can be further at least one work in following (a)~(c) Sequence.

(a) the above-mentioned 1st or the 2nd acetic acid stream is distilled and be separated into the bottom product stream for being enriched with high boiling ingredient and with Acetic acid stream before being distilled takes off high boiling process compared to the 3rd acetic acid stream that acetic acid is more enriched with

(b) above-mentioned 1st or the 2nd or the 3rd acetic acid stream is handled using ion exchange resin and obtains the 4th acetic acid stream It is adsorbed and removed process

(c) above-mentioned 1st or the 2nd or the 3rd or the 4th acetic acid stream is distilled into the acetic acid stream before being obtained and being distilled Compared to the article process for the 5th acetic acid stream that acetic acid is more enriched with

In addition, the preparation method of acetic acid of the invention can also be included using more than one destilling tower, from by above-mentioned richness The acetaldehyde that acetaldehyde is separated at least part of condensate liquid obtained from the stream condensation of collection low boiling ingredient is separated off system.

In the preparation method of such acetic acid of the invention, preferably by selected from from reactive tank discharge gas, come from The discharge gas of evaporator tank, destilling tower in above-mentioned separation process discharge gas and be separated off from above-mentioned acetaldehyde One or more of the discharge gas of destilling tower in system exhaust gas supplies to absorption tower and absorbs process for the 1st.

In addition, in the preparation method of such acetic acid of the invention the enrichment obtained can will be separated in diffusing procedure The tower top stream of iodomethane is recycled to reaction process, evaporization process, and/or distillation process.This is because, iodomethane is in reactive tank In reaction process in can be usefully recycled.

In addition, in the preparation method of such acetic acid of the invention, in the feelings for having used the 2nd absorbent comprising acetic acid Under condition, preferably by diffusing procedure separation obtain enrichment acetic acid bottom product stream be recycled to selected from above-mentioned reaction process, Evaporization process, de- low boiling process, dehydration procedure and take off more than one process in high boiling process.This is because, for acetic acid, It is not discarded but make it includes in the final article when can realize effective use, and for residual included in above-mentioned tower reactor sometimes High boiling ingredient other than acetic acid in liquid stream can be separated off in taking off high boiling process.It should be noted that being higher than in boiling point The ingredient (in exhaust gas micro containing catalyst, high boiling hydrocarbon, the higher boiling carboxylic acid such as lithium iodide, rhodium catalyst etc.) of acetic acid it is dense In the case that degree of spending increases, the temperature that will lead to the destilling tower in diffusing procedure rise and make corrosion in destilling tower into Row, and due to corrosion, it can be mixed into the material of destilling tower, the composition that thus will lead to bottom product changes and then causes to absorb Absorption efficiency in process reduces, therefore preferably bottom product is recycled to outside system as needed.

In addition, in the preparation method of such acetic acid of the invention, the case where having used includes 1 absorbent of water Under, preferably by the 1st recycling solution comprising water obtained in the 1st absorption process to being selected from above-mentioned reactive tank, be used to store More than one device in the decanter of above-mentioned condensate liquid, above-mentioned dehydrating tower and above-mentioned de- high boiling tower.This is because, reacting In slot, water can be because of the conversion reaction (H of carbon monoxide₂O+CO→H₂+CO₂) and be consumed.In addition, being recycled to above-mentioned decantation In the case where water phase in device, it can be handled jointly with the water phase.In addition, water exists in the case where being recycled to dehydrating tower Dehydration column overhead is concentrated, and in the case where being recycled to de- high boiling tower, water is concentrated taking off high boiling column overhead, is followed again thereafter Ring or through waste treatment.

Hereinafter, being illustrated for an embodiment of the preparation method of acetic acid of the invention.Fig. 4 is to show acetic acid An example of the preparation flow figure (methanol method carbonylating process) of one embodiment of preparation system.The acetic acid preparation flow is related to Acetic acid preparation facilities have reactive tank 1, evaporator tank 2, destilling tower 3, decanter 4, destilling tower 5, destilling tower 6, amberlite Rouge tower 7, washing system 8, acetaldehyde be separated off system 9, condenser 1a, 2a, 3a, 5a, 6a, heat exchanger 2b, reboiler 3b, 5b, 6b, route 11~56 and pump 57, are constituted in a manner of it continuously can prepare acetic acid.

In the preparation method of the acetic acid of present embodiment, in reactive tank 1, evaporator tank 2, destilling tower 3, destilling tower 5, distillation In tower 6 and exchange resin tower 7, reaction process, evaporization process (flash process), the 1st distillation process, the 2nd are carried out respectively Distillation process, the 3rd distillation process and it is adsorbed and removed process.1st distillation process also referred to as de- low boiling process, the 2nd distillation process Referred to as dehydration procedure, the 3rd distillation process also referred to as take off high boiling process.It should be noted that in the present embodiment, process not office Be limited to it is above-mentioned, particularly, including be attached to destilling tower 5, destilling tower (de- high boiling tower) 6, exchange resin tower 7, acetaldehyde separation The case where equipment of removing system 9 (de- acetaldehyde tower etc.).Alternatively, it is also possible to as described later, under exchange resin tower 7 Trip setting product tower.

Reactive tank 1 is the unit for carrying out reaction process.The reaction process is for by shown in following reaction equations (1) Reaction (carbonylation of the methanol) process that is continuously generated acetic acid.In the normal operation of acetic acid preparation facilities Under, in reactive tank 1, there is the reaction mixture that for example stirred using blender.Reaction mixture includes as raw material Methanol and carbon monoxide, metallic catalyst, co-catalyst, water, as the acetic acid and various by-products of preparation target, liquid phase with Gas phase is in equilibrium state.

CH₃OH+CO→CH₃COOH(1)

Raw material in reaction mixture is liquid methanol and gasiform carbon monoxide.Methanol is from methanol storage unit (diagram is omitted) is continuously fed reactive tank 1 with given flow by route 11.Carbon monoxide is from carbon monoxide storage portion (diagram is omitted) is continuously fed reactive tank 1 with given flow by route 12.Carbon monoxide is not necessarily pure Carbon monoxide can also contain (such as 5 mass % or less, preferably 1 mass % or less) such as nitrogen, hydrogen, carbon dioxide, oxygen on a small quantity Deng other gases.

Metallic catalyst in reaction mixture is the substance for promoting the carbonylation of methanol, be can be used for example Rhodium catalyst, iridium catalyst.As rhodium catalyst, can be used for example with chemical formula [Rh (CO)₂I₂]^-The rhodium complex of expression. As iridium catalyst, can be used for example with chemical formula [Ir (CO)₂I₂]^-The iridium complex of expression.It is excellent as metallic catalyst Select metal complex catalyst.Liquid phase (reaction mixture) relative to reaction mixture is whole, the catalysis in reaction mixture The concentration (being converted with metal) of agent is, for example, 200~10000 mass ppm, is preferably 300~5000 mass ppm, further preferred For 400~2500 mass ppm.

Co-catalyst is the iodide for assisting the effect of above-mentioned catalyst, and such as iodomethane, ionic iodine can be used Compound.Iodomethane can show the effect for promoting the catalytic action of above-mentioned catalyst.Liquid phase relative to reaction mixture is whole, The concentration of iodomethane is, for example, 1~20 mass %, preferably 5~15 mass %.Ionic iodide are to generate in reaction solution The iodide (especially cationic metal iodide) of iodide ion can show effect, the suppression of above-mentioned catalyst stabilization of sening as an envoy to The effect of side reaction processed.As ionic iodide, it can be mentioned, for example the alkaline metal iodides such as lithium iodide, sodium iodide and potassium iodide Deng.Liquid phase relative to reaction mixture is whole, and the concentration of the ionic iodide in reaction mixture is such as 1~25 matter Measure %, preferably 5~20 mass %.In addition, also can be used using the situation such as iridium catalyst as co-catalyst Ruthenium compound, osmium compound.The usage amount of these compounds is with summation meter, such as relative to 1 mole of iridium (being converted with metal) 0.1~30 mole (being converted with metal), preferably 0.5~15 mole (being converted with metal).

For water in reaction mixture in terms of the reaction mechanism of the carbonylation of methanol, being must for generating acetic acid The ingredient wanted, in addition, for the water soluble ingredient of reaction system it is solubilized for be also necessary ingredient.It is mixed relative to reaction The liquid phase for closing object is whole, the concentration of the water in reaction mixture be, for example, 0.1~15 mass %, preferably 0.5~10 mass %, More preferably 1~6 mass %, further preferably 1.5~4 mass %.It is removed required for water during inhibiting acetic acid purification Energy, promote acetic acid preparation efficient activity aspect, water concentration is preferably 15 mass % or less.In order to control water concentration, The water of given flow can be continuously fed to reactive tank 1.

Acetic acid in reaction mixture includes: the second being dosed in advance in reactive tank 1 before the operating of acetic acid preparation facilities Acid and as the carbonylation of methanol principal product and the acetic acid that generates.Such acetic acid can be in the reaction system as molten Agent plays a role.Liquid phase relative to reaction mixture is whole, and the concentration of the acetic acid in reaction mixture is such as 50~90 matter Measure %, preferably 60~80 mass %.

As the Main By product for including in reaction mixture, it can be mentioned, for example methyl acetates.The methyl acetate can pass through Acetic acid is generated with reacting for methanol.Liquid phase relative to reaction mixture is whole, the methyl acetate in reaction mixture it is dense Degree is such as 0.1~30 mass %, preferably 1~10 mass %.

As the by-product for including in reaction mixture, hydrogen iodide can also be enumerated.From the reaction of the carbonylation of methanol It is to inevitably result from the iodate in the case where stating such catalyst, co-catalyst in use from the aspect of mechanism Hydrogen.Liquid phase relative to reaction mixture is whole, and the concentration of the hydrogen iodide in reaction mixture is such as 0.01~2 matter Measure %.

In addition, as by-product, it can be mentioned, for example: hydrogen, methane, carbon dioxide, acetaldehyde, crotonaldehyde, 2- ethyl crotonaldehyde, Idoalkanes such as dimethyl ether, alkanes, formic acid and propionic acid and iodohexane and iodine decane etc..In addition, in the reactive mixture may be used The metals such as the iron, nickel, chromium, manganese, the molybdenum that are generated including the corrosion due to device (hereinafter also referred to " corrosion metals "), Yi Jizuo For the cobalt, zinc, copper etc. of other metals.Also above-mentioned corrosion metals and other metals are referred to as " corrosion metal etc. ".

In the reactive tank 1 that there is above such reaction mixture, reaction temperature may be set to such as 150~250 DEG C, Reaction pressure in terms of integral pressure may be set to such as 1.5~3.5MPa (absolute pressure), and carbon monoxide pressure of tension may be set to Such as 0.4~1.8MPa (absolute pressure), preferably 0.6~1.6MPa (absolute pressure), further preferably 0.9~1.4MPa (absolute pressure).

In the steam in the gas phase portion in reactive tank 1 in device operating, including for example: carbon monoxide, hydrogen, methane, two Carbonoxide, nitrogen, oxygen, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde, formic acid and propionic acid etc..It should Steam can be extracted out of reactive tank 1 by route 13.By adjusting the extracted amount of steam, can control in reactive tank 1 Pressure, such as the pressure in reactive tank 1 can be made to keep constant.The steam extracted out of reactive tank 1 is imported into condenser 1a.

Condenser 1a makes its partial condensation by the way that the steam of autoreaction slot in future 1 is cooling, thus be divided into condensation ingredient and Gas componant.Be condensed into point includes such as iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde, formic acid With propionic acid etc., reactive tank 1 is fed to by route 14 from condenser 1a and is recycled.Gas componant includes a such as oxygen Change carbon, hydrogen, methane, carbon dioxide, nitrogen, oxygen, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde and Formic acid etc. is supplied to washing system 8 from condenser 1a by route 15.

It should be noted that can be in Fig. 4 and carry out the gas componant (route 20) of condenser 2a, carry out condenser The gas componant (route 32) of 3a, the gas componant (route 37) for carrying out condenser 5a and the gas componant for carrying out condenser 6a (route 45) all interflow to route 15 and is supplied to washing system 8 (pattern A), can also be only from the gas of condenser 1a Ingredient is supplied to washing system 8 via route 15, in addition, carry out condenser 3a, the gas componant of 5a, 6a (route 32, 37,45) all interflow to route 20 and is supplied to washing system 8 (pattern B).For for the pattern A the case where, such as from The gas componant of condenser 1a via the route 58 or route 77 in route 15 and Fig. 2 or washing system shown in Fig. 38 and It is supplied to absorption tower 81 or absorption tower 85.For for the pattern B the case where, for example, come the gas componant of condenser 1a via Route 58 in route 15 and washing system shown in FIG. 18 and be supplied to absorption tower 81, the gas componant warp of current through line 20 The route 62 in washing system 8 as shown in Figure 1 and be supplied to absorption tower 82.

In washing system 8, as described above, can be by absorbing process and as needed by expanding by the 1st and the 2nd Day labor sequence always separates and recovers useful component (for example, iodomethane, methanol, two in the gas componant (route 15) of condenser 1a Methyl ether, water, methyl acetate, acetic acid etc.).In the separation and recovery, in the present embodiment using using for capturing gas The absorbing liquid of useful component in ingredient and the damp process carried out.For example, can be used aftermentioned from destilling tower as absorbing liquid The condensation ingredient of 6 steam.The useful component (for example, iodomethane etc.) of separation and recovery is from washing system 8 (especially from diffusion The route 73 of 84 tower top of destilling tower in process) reactive tank 1 is imported into via recirculation circuit 48 and is recycled.It needs Illustrate, though it is not shown, for route 48, the charging of each condenser of condenser 1a, 2a, 3a, 5a can be directed into Useful component is carried out cooling condensation and recycled by route.For capturing the gas after useful component (for example, in Fig. 1 and Fig. 2 Route 71) can be discarded via route 49.Furthermore it is possible to which the gas after useful component will be captured (for example, the line in Fig. 3 Road 73a, 89) condensation ingredient is separated using condenser, and/or is recycled to absorption tower.It should be noted that being arranged from route 49 Gas out can be used as the source CO of the aftermentioned bottom for importing evaporator tank 2 or raffinate stream recirculation circuit 18,19 and be subject to benefit With.About the processing in washing system 8 with and subsequent recycling and discarded, for being supplied to washing system from other condensers The aftermentioned gas componant (route 20,32,37,45) of system 8 is also same.

In reactive tank 1 in device operating, it is continuously generated acetic acid as described above.Such reaction comprising acetic acid After mixture is continuously extracted out of reactive tank 1 with given flow, subsequent evaporation is fed to by route 16 Slot 2.

Evaporator tank 2 is the unit for being evaporated process (flash process).The evaporization process is for passing through route 16 (reaction mixture supply lines) make the reaction mixture for continuously importing evaporator tank 2 partly evaporate and be divided into vapor stream and (wave Send out phase) and raffinate stream (low volatilization phase) process.

Evaporation can be brought it about without heating and depressurizing to reaction mixture, it can also be by anti- Mixture is answered to be depressurized in heating to bring it about evaporation.In evaporization process, the temperature of vapor stream is such as 100~260 DEG C, It is preferred that 120~200 DEG C, the temperature of raffinate stream is such as 80~200 DEG C, preferably 100~180 DEG C, in slot pressure be such as 50~ 1000kPa (absolute pressure).

In addition, the ratio about the vapor stream and raffinate stream that are separated in evaporization process, by quality ratio for example, 10/90 ~50/50 (vapor stream/raffinate stream).The steam generated in this process is including, for example, iodomethane, hydrogen iodide, water, methyl acetate, second The iodos such as acid, dimethyl ether, methanol, acetaldehyde, formic acid and propionic acid and iodoethane, iodopropane, iodobutane, iodohexane and iodine decane Alkane etc. is continuously extracted out of evaporator tank 2 to route 17 (vapor stream pumping-out line).

A part of the vapor stream extracted out of evaporator tank 2 by continuously import condenser 2a, the vapor stream it is other Part is continuously directed into subsequent destilling tower 3 by route 21.The acetic acid concentration of above-mentioned vapor stream is, for example, 40~85 Quality % (preferably 50~85 mass %), 50~75 mass % (such as 55~75 mass %) are more preferably, iodomethane concentration For example, 2~50 mass % (preferably 5~30 mass %), water concentration are, for example, 0.2~20 mass % (preferably 1~15 matter Measure %), methyl acetate concentration is, for example, 0.2~50 mass % (preferably 2~30 mass %).It should be noted that above-mentioned steaming The iodohexane concentration of air-flow is, for example, 0.1~10000 mass ppb, is usually 0.5~1000 mass ppb, is in many cases 1 ~100 mass ppb (such as 2~50 mass ppb).

The raffinate stream generated in this process includes the catalyst and co-catalyst (iodomethane, iodine contained in reaction mixture Change lithium etc.), non-volatile and remaining water, methyl acetate, acetic acid, formic acid and propionic acid etc. in this process, using pump 57, continuously Heat exchanger 2b is fed to from evaporator tank 2 by route 18.Heat exchanger 2b carries out the raffinate stream from evaporator tank 2 cold But.Raffinate stream after cooling is recycled by continuously reactive tank 1 is directed by route 19 from heat exchanger 2b.It needs Illustrate, route 18 and route 19 are known as raffinate stream recirculation circuit together.The acetic acid concentration of above-mentioned raffinate stream is, for example, 55~90 mass %, preferably 60~85 mass %.

Condenser 2a makes its partial condensation by the vapor stream cooling of spontaneous evaporation in future slot 2, to be divided into condensation ingredient And gas componant.It is condensed into point including, for example, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde, first Acid and propionic acid etc. are fed to reactive tank 1 by route 22,23 from condenser 2a and are recycled.Gas componant includes example As carbon monoxide, hydrogen, methane, carbon dioxide, nitrogen, oxygen, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, Acetaldehyde and formic acid etc. are supplied to washing system 8 from condenser 2a by route 20,15.Acetic acid in above-mentioned reaction process When generation reaction is exothermic reaction, a part accumulated in the heat of reaction mixture can shift in evaporization process (flash process) To the steam generated by reaction mixture.The condensation ingredient of the steam generated by the cooling in condenser 2a is recycled To reactive tank 1.That is, in the acetic acid preparation facilities, it is anti-that the carbonylation in methanol is removed well using condenser 2a efficiency Answer the heat of middle generation.

Destilling tower 3 is the unit for carrying out the 1st distillation process, can be considered so-called de- low boiling in the present embodiment Tower.1st distillation process be for the vapor stream for being continuously directed into destilling tower 3 carry out distillation processing and be separated off low boiling at The process divided.More specifically, in the 1st distillation process, above-mentioned vapor stream is distilled and be separated into enrichment selected from iodomethane and The tower top stream of at least one of acetaldehyde low boiling ingredient and the acetic acid stream for being enriched with acetic acid.

Destilling tower 3 includes the rectifying column such as column plate tower and packed column.Using column plate tower as destilling tower 3 in the case where, Its theoretical cam curve be such as 5~50 layers, reflux ratio according to theoretical cam curve and for example, 0.5~3000.In destilling tower 3 Tower top pressure is set as such as 80~160kPaG by portion, and tower bottom pressure is set higher than tower top pressure, for example, 85~ 180kPaG.In the inside of destilling tower 3, tower top temperature is set as example than the low boiling point of the acetic acid under setting tower top pressure 90~130 DEG C of temperature, by column bottom temperature be set as the temperature 120 for example more than the boiling point for setting the acetic acid under tower bottom pressure~ 165 DEG C (preferably 125~160 DEG C).

Vapor stream from evaporator tank 2 is continuously imported destilling tower 3 by route 21, and from the tower top of destilling tower 3 Portion, the steam as tower top stream are continuously extracted to route 24.From the tower bottom of destilling tower 3, bottom product is continuously mentioned It takes to route 25.3b is reboiler.Second from the height and position between the top of tower and tower bottom of destilling tower 3, as effluent Acid stream (the 1st acetic acid stream；Liquid) it is continuously extracted from route 27.

Compared with above-mentioned bottom product and effluent from destilling tower 3, in the steam extracted from the top of tower of destilling tower 3 In be more lower than the ingredient (low boiling point component) of acetic acid comprising boiling point, including for example: iodomethane, hydrogen iodide, water, acetic acid first Ester, dimethyl ether, methanol, acetaldehyde and formic acid etc..It also include acetic acid in the steam.Such steam is by route 24 by continuously It is directed into condenser 3a.

Condenser 3a by will the steam from destilling tower 3 is cooling make its partial condensation, thus be divided into condensation ingredient and Gas componant.Be condensed into point including, for example, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde and Formic acid etc. is continuously imported decanter 4 from condenser 3a by route 28.The condensation ingredient of decanter 4 is imported by liquid separation For water phase (upper phase) and organic phase (iodomethane phase；Lower phase).

It include water and such as iodomethane, hydrogen iodide, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde and formic acid in water phase Deng.Comprising iodomethane and such as hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde and formic acid in organic phase.

In the present embodiment, a part of water phase is back to destilling tower 3, the other parts warp of water phase by route 29 Route 29,30,23 is crossed to be directed into reactive tank 1 and recycle.A part of organic phase is fed to instead by route route 31,23 It answers slot 1 and recycles.The other parts of organic phase, and/or the other parts of water phase, via route 31,50, and/or route 30, 51 and be fed to acetaldehyde and be separated off system 9.It should be noted that can be by the 1st or the 2nd recycling solution comprising water extremely Water phase in decanter 4.Hydration in 1st or the 2nd solution flow to jointly processed with water phase after above-mentioned water phase.

It is separated off in process in the acetaldehyde for having used acetaldehyde to be separated off system 9, it will be contained in organic phase and/or water phase Acetaldehyde utilize well known method, such as distillation, extraction or these combination and be separated off.The acetaldehyde isolated passes through Route 53 and be discharged to outside device.In addition, the useful component (such as iodomethane etc.) contained in organic phase and/or water phase passes through Route 52,23 is recycled to reactive tank 1 and is reused.

Fig. 5 is to show the schematic flow diagram of an example that acetaldehyde is separated off system.According to the process, such as will be described Organic phase is supplied by route 101 to destilling tower (the in the case where acetaldehyde is separated off process and is handled, by organic phase 1 de- acetaldehyde tower) 91 distilled and be separated into enrichment acetaldehyde tower top stream (route 102) and be enriched with iodomethane raffinate stream (line Road 103).The tower top stream is condensed using condenser 91a, a part of condensate liquid is made to be back to the top of tower of destilling tower 91 (route 104) supplies the other parts of condensate liquid to extraction tower 92 (route 105).

For being supplied to the condensate liquid of above-mentioned extraction tower 92, extraction processing is carried out using the water imported by route 109.Through Extract liquor obtained from extraction processing is supplied to destilling tower (the 2nd de- acetaldehyde tower) 93 and is distilled and divided by route 107 Raffinate stream (route 113) from tower top stream (route 112) and enrichment water for enrichment acetaldehyde.Then, make richness using condenser 93a The tower top stream condensation for collecting acetaldehyde, makes a part of condensate liquid be back to the top of tower (route 114) of destilling tower 93, condensate liquid its It is outer (route 115) that he is partially discharged to system.

In addition, the raffinate stream of the enrichment iodomethane of the bottom product as the 1st de- acetaldehyde tower 91, being obtained in extraction tower 92 It is enriched with the raffinate stream of the enrichment water of the raffinate (route 108) of iodomethane and the bottom product as the 2nd de- acetaldehyde tower 93, Respectively be recirculated to reactive tank 1 by route 103,111,113, or be recycled to the appropriate site of technique and by sharp again With.For example, the raffinate of the enrichment iodomethane obtained in extraction tower 92, can be recirculated to destilling tower 91 by route 110. 113 liquid is discharged to outside usually as draining.Be not condensed in condenser 91a, 93a gas (route 106, 116) it, is carried out absorbing processing or by carry out waste treatment in washing system 8.

In addition, the process according to Fig. 5 by above-mentioned water phase in the case where acetaldehyde is separated off process and is handled, example Such as, water phase is supplied in the tower that destilling tower (the 1st de- acetaldehyde tower) 91 is distilled and is separated into enrichment acetaldehyde by route 101 Top stream (route 102) and the raffinate stream (route 103) for being enriched with water.The tower top stream is condensed using condenser 91a, makes to condense A part of liquid is back to the top of tower (route 104) of destilling tower 91, and the other parts of condensate liquid are supplied to 92 (line of extraction tower Road 105).

For being supplied to the condensate liquid of the extraction tower 92, extraction processing is carried out using the water imported by route 109.Through The extract liquor that extraction processing obtains is supplied to destilling tower (the 2nd de- acetaldehyde tower) 93 and is distilled and separated by route 107 To be enriched with the tower top stream (route 112) of acetaldehyde and being enriched with the raffinate stream (route 113) of water.Then, make to be enriched with using condenser 93a The tower top stream of acetaldehyde condenses, and a part of condensate liquid is made to be back to the top of tower (route 114) of destilling tower 93, condensate liquid other It is outer (route 115) that part is discharged to system.

In addition, the raffinate stream of the enrichment water of the bottom product as the 1st de- acetaldehyde tower 91, the enrichment obtained in extraction tower 92 The raffinate stream of the enrichment water of the raffinate (route 108) of iodomethane and the bottom product as the 2nd de- acetaldehyde tower 93, respectively It is recirculated to reactive tank 1 by route 103,111,113, or is recycled to the appropriate site of technique and is reused.Example Such as, the raffinate of the enrichment iodomethane obtained in extraction tower 92 can be recirculated to destilling tower 91 by route 110.113 Liquid is discharged to outside usually as draining.In the gas (route 106,116) that condenser 91a, 93a are not condensed, Absorption processing is carried out in washing system 8, or by carry out waste treatment.

For being originated from the acetaldehyde of the above-mentioned technique stream for including at least water, acetic acid (AC), iodomethane (MeI) and acetaldehyde (AD) For, in addition to the method described above, it can also be separated off using extractive distillation.For example, can be by the way that the technique will be made Organic phase obtained from flow point liquid and/or water phase (feeding liquid) are supplied in destilling tower (extraction distillation column), and extractant is (logical The concentration domain that the iodomethane and acetaldehyde Chang Weishui) importeding into destilling tower are concentrated is (for example, from tower top to feeding liquid supply position Space), will be extracted from the liquid (extract liquor) fallen of the concentration domain as effluent (pump-around stream), make the effluent liquid separation Water phase and organic phase, and the water phase is distilled and acetaldehyde is discharged to outside system.

It should be noted that there are the liquid that in the case where more water, can will be fallen from the concentration domain in destilling tower Body is extracted as effluent, without the extractant is imported into destilling tower.For example, can be received in the distillation tower configuration The unit (chimney tray etc.) for the liquid (extract liquor) fallen from above-mentioned concentration domain, will be in (the extraction of the received liquid of the unit Liquid) it is extracted as effluent.

The importing position of extractant is preferably in the top of the supply position of the feeding liquid, more preferably near tower top. For the extraction position of effluent, preferably in the short transverse of tower, be extractant importing position lower section and it is described into The top of the supply position of feed liquid.According to this method, extractant (usually water) can use and from iodomethane and acetaldehyde Acetaldehyde is extracted with high concentration in concentrate, simultaneously as can will make between the imported parts of extractant and effluent position Utilized for extraction domain, thus can with a small amount of extractant efficiency extract acetaldehyde well.Thus, for example with from distillation The method that the tower bottom of tower (extraction distillation column) extracts the extract liquor based on extractive distillation is compared, and destilling tower can be greatly decreased The number of plies, while steam load can also be reduced.Further, since being distilled using a small amount of extractant with by the full gear of above-mentioned Fig. 5 The method being combined with water extraction compares ratio (MeI/AD ratio) of the iodomethane relative to acetaldehyde in water extract that can reduce, Therefore acetaldehyde can be removed under conditions of loss of the inhibition iodomethane to outside system.

Acetaldehyde concentration in above-mentioned effluent is significantly higher than the acetaldehyde concentration in the feeding liquid and bottom product (tower bottom liquid). In addition, with regard to acetaldehyde in above-mentioned effluent for the ratio of iodomethane, be greater than in feeding liquid and bottom product acetaldehyde relative to The ratio of iodomethane.

It should be noted that organic phase obtained from the effluent liquid separation (iodomethane phase) can will be made to be recycled to the steaming Evaporate tower.In this case, for making the recirculation position of organic phase obtained from the effluent liquid separation, in the short transverse of tower On, the lower section of position, the preferably top in the supply position of the feeding liquid are preferably extracted in the effluent.

Furthermore it is possible to by for the ingredient (such as methyl acetate etc.) for constituting the organic phase obtained by the technique flow point liquid Miscibility solvent imported into the destilling tower (extraction distillation column).As the miscibility solvent, can enumerate such as acetic acid, Ethyl acetate etc..For the importing position of the miscibility solvent, in the short transverse of tower, position preferably is extracted in the effluent The lower section set, the preferably top in the supply position of the feeding liquid.In addition, with regard to the miscibility solvent importing position and Speech, in the case where organic phase obtained from above-mentioned effluent liquid separation will be made to be recycled to the destilling tower, preferably in its recycling position The lower section set.

The organic phase as obtained from will make the effluent liquid separation is recycled to destilling tower or leads the miscibility solvent Enter to destilling tower, the methyl acetate concentration in the extract liquor extracted as effluent can be reduced, can reduce makes the extract liquor Methyl acetate concentration in water phase obtained from liquid separation, so as to inhibit iodomethane being mixed into water phase.

The theoretical tray of above-mentioned destilling tower (extraction distillation column) is, for example, 1~100 layer, preferably 2~50 layers, is more preferably 3~30 layers, further preferably 5~20 layers, with existing for taking off 80~100 layers of the destilling tower of acetaldehyde, extraction distillation column It compares, well can be separated off acetaldehyde with few number of plies efficiency.

The matter of the flow of the flow and feeding liquid (making organic phase and/or water phase obtained from technique flow point liquid) of extractant Amount ratio (the former/the latter) can be selected from 0.0001/100~100/100 range, usually 0.0001/100~20/100, It is preferred that 0.001/100~10/100, more preferable 0.01/100~8/100, further preferred 0.1/100~5/100.

The tower top temperature of above-mentioned destilling tower (extraction distillation column) is, for example, 15~120 DEG C, preferably 20~90 DEG C, more preferable 20 ~80 DEG C, it is 25~70 DEG C further preferred.Tower top pressure is with absolute manometer, for example, 0.1~0.5MPa degree.The distillation The other conditions of tower (extraction distillation column) can with it is previous identical for taking off destilling tower, the extraction distillation column of acetaldehyde.

Fig. 6 is to show the schematic flow diagram of an example that the above-mentioned acetaldehyde that extractive distillation is utilized is separated off system. In this example, organic phase obtained from the technique flow point liquid and/or water phase (feeding liquid) will be made by supply lines 201 and It is supplied in the middle section (position between tower top and tower bottom) of destilling tower 94, and imports water by route 202 near tower top, Extractive distillation is carried out in destilling tower 94 (extraction distillation column).

In the top of the supply position of the feeding liquid of destilling tower 94, configured with for receive from tower iodomethane and The chimney tray 200 for the liquid (extract liquor) that the concentration domain that acetaldehyde is concentrated is fallen.In the extractive distillation, preferably full dose is mentioned The liquid on chimney tray 200 is taken, decanter 95 is directed by route 208 and carries out liquid separation.

Water phase (containing acetaldehyde) in decanter 95 is directed into cooler 95a by route 212 to cool down, is made molten in water phase The iodomethane of solution carries out two-phase separation, and makes its liquid separation using decanter 96.Water phase in decanter 96 is passed through into route 216 And supply to destilling tower 97 (de- acetaldehyde tower) and distilled, it is cold that the steam of tower top by route 217 is directed into condenser 97a It is solidifying, so that a part of condensate liquid (mainly acetaldehyde and iodomethane) is back to the tower top of destilling tower 97, residue or it is discarded or Person supplies by route 220 to destilling tower 98 (extraction distillation column).

Water is imported by route 222 near the tower top of destilling tower 98, carries out extractive distillation.The steam of tower top passes through Route 223 is directed into condenser 98a and condenses, and a part of condensate liquid (mainly iodomethane) is made to be back to top of tower, remaining Object is recycled to reaction system by route 226, but also has the situation outside discharge system.For the organic phase in decanter 95 Whole amount is preferably recycled to the position of the chimney tray 200 of destilling tower 94 by (iodomethane phase) by route 209,210 Lower section.A part of the water phase of decanter 95 and the organic phase of decanter 96 pass through respectively route 213,210, route 214, 210 are recycled to destilling tower 94, but also have the case where not recycling.A part of the water phase of decanter 95 can be used as destilling tower Extractant (water) in 94 and utilize.The a part of of the water phase of decanter 96 can be recycled to destilling tower by route 210 94。

According to circumstances (for example, the case where containing methyl acetate in the feeding liquid etc.) can will be directed to and constitute by institute State miscibility solvent (the acetic acid, ethyl acetate etc.) warp of the ingredient (such as methyl acetate etc.) for the organic phase that technique flow point liquid obtains It crosses route 215 and is fed into destilling tower 94, improve distillation efficiency.With regard to miscibility solvent to for the supply position of destilling tower 94, In the top of the feeding liquid supply unit (interconnecting piece of route 201) and the lower section of the interconnecting piece in recirculation circuit 210.It steams The bottom product for evaporating tower 94 is recycled to reaction system.

So that the steam of the tower top of destilling tower 94 is directed into condenser 94a by route 203 and is condensed, condensate liquid is being decanted 99 liquid separation of device, organic phase are back to the top of tower of destilling tower 94 by route 206, and water phase is directed into decanter by route 207 95。

The bottom product (water is principal component) of destilling tower 97, the bottom product of destilling tower 98 (extraction distillation column) (contain few The acetaldehyde of amount) pass through outside the removing to system of route 218,224 or be recycled to reaction system respectively.Condenser 94a, The gas (route 211,221,227) that 97a, 98a are not condensed is in washing system 8 by absorbing processing or by discarded place Reason.

Fig. 7 is to show the exemplary flow for other examples that the above-mentioned acetaldehyde that extractive distillation is utilized is separated off system Figure.In this example, the condensate liquid of the steam of the tower top of destilling tower 94 is directed into and stores tank 100, its whole amount is passed through into line Road 206 is back to the top of tower of destilling tower 94.In addition to this, identical as the example of Fig. 6.

Fig. 8 is to show the exemplary flow for another example that the above-mentioned acetaldehyde that extractive distillation is utilized is separated off system Figure.In this example, the liquid on chimney tray 200 is subjected to full dose extraction, by route 208 without decanter 95 ground are introduced directly into cooler 95a and are cooled down, supply to decanter 96.In addition to this, identical as the example of Fig. 7.

In above-mentioned Fig. 4, condenser 3a generate gas part contain for example carbon monoxide, hydrogen, methane, carbon dioxide, Nitrogen, oxygen, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde and formic acid etc. pass through from condenser 3a Route 32,15 is supplied to washing system 8.Reach iodomethane, the hydrogen iodide, water, acetic acid first in the gas part of washing system 8 Ester, acetic acid, dimethyl ether, methanol, acetaldehyde and formic acid etc. are absorbed by liquid absorption in washing system 8.Include methanol or acetic acid in use In the case that the absorbing liquid of methyl esters is as the absorbing liquid in the 1st or the 2nd absorption process, hydrogen iodide utilizes and the methanol in absorbing liquid Or methyl acetate reaction and generate iodomethane.In turn, the liquid portion containing useful components such as the iodomethane (comes from destilling tower The tower top stream of 84 tower tops) reactive tank 1 can be recycled to by recirculation circuit 48,23 from washing system 8 and be reused.

From the bottom product that the tower bottom of destilling tower 3 extracts, with from destilling tower 3 tower top stream and effluent compared with More include the ingredient (higher boiling ingredient) that boiling point is higher than acetic acid, is urged including, for example, propionic acid and the above-mentioned of entrainment Agent, co-catalyst.In the bottom product, also comprising acetic acid, iodomethane, methyl acetate and water etc..In present embodiment In, a part of such bottom product is continuously imported evaporator tank 2 by route 25,26 and is recycled, and tower reactor is residual The other parts of liquid are continuously imported reactive tank 1 by route 25,23 and are recycled.

The 1st acetic acid stream that is continuously extracted from destilling tower 3 with lateral flow format, and is continuously imported destilling tower 3 Vapor stream is compared, and acetic acid is more enriched with.That is, the acetic acid concentration of the 1st acetic acid stream is higher than the acetic acid concentration of the vapor stream.1st acetic acid The acetic acid concentration of stream is, for example, 90~99.9 mass %, preferably 93~99 mass %.In addition, in the 1st acetic acid stream in addition to acetic acid with Outside, also including, for example, iodomethane, hydrogen iodide, water, methyl acetate, dimethyl ether, methanol, acetaldehyde, formic acid and propionic acid and iodine second Idoalkanes such as alkane, iodopropane, iodobutane, iodohexane and iodine decane etc..

It should be noted that with regard to route 27 for the link position of destilling tower 3, in the short transverse of destilling tower 3 On, can as shown in figure, the route 21 relative to destilling tower 3 link position top but it is also possible to be relative to The lower section of the link position of the route 21 of destilling tower 3 can also be the link position phase with the route 21 relative to destilling tower 3 Together.The 1st acetic acid stream from destilling tower 3 is with given flow is consecutively passed route 27 and imports to subsequent destilling tower 5. It should be noted that as destilling tower 3 effluent and the tower of the 1st acetic acid stream, the tower bottom liquid of destilling tower 3 or destilling tower 3 that extracts The condensate liquid of the steam of bottom can continuously import aftermentioned destilling tower without destilling tower 5 (dehydration procedure) but directly 6。

In the 1st acetic acid stream of current through line 27, it can supply or add by route 55 (potassium hydroxide importing route) Add potassium hydroxide.Potassium hydroxide can be supplied or be added with solution forms such as such as aqueous solutions.By being supplied to the 1st acetic acid stream Or addition potassium hydroxide, it is possible to reduce the hydrogen iodide in the 1st acetic acid stream.Specifically, hydrogen iodide reacted with potassium hydroxide and Generate potassium iodide and water.Thus, it is possible to reduce as hydrogen iodide and caused by the devices such as destilling tower corrosion.It needs to illustrate It is that potassium hydroxide can supply or be added to the suitable place in this technique there are hydrogen iodide.It should be noted that in work The potassium hydroxide added in skill makes it also generate potassium acetate with acetic acidreaction.

Destilling tower 5 is the unit for carrying out the 2nd distillation process, can be considered as so-called dehydration in the present embodiment Tower.2nd distillation process is to be further purified for carrying out distillation processing to the 1st acetic acid stream for being continuously directed into destilling tower 5 The process of acetic acid.

Destilling tower 5 includes the rectifying column such as column plate tower and packed column.Using the case where column plate tower is as destilling tower 5 Under, theoretical tray is, for example, 5~50 layers, reflux ratio according to theoretical cam curve and for example, 0.2~3000.It is steamed being located at the 2nd Tower top pressure is set as such as 150~250kPaG, tower bottom pressure is set higher than tower by the inside for evaporating the destilling tower 5 of process Pressure on top surface, for example, 160~290kPaG.In the inside for the destilling tower 5 for being located at the 2nd distillation process, tower top temperature can for example be set It is 130~160 DEG C of temperature of the boiling point higher than the boiling point for setting the water under tower top pressure and lower than acetic acid, column bottom temperature for example may be used 150~175 DEG C of temperature be set as more than the boiling point for setting the acetic acid under tower bottom pressure.

From the top of tower of destilling tower 5, the steam as tower top stream is continuously extracted to route 33.From the tower of destilling tower 5 Bottom, bottom product are continuously extracted to route 34.5b is reboiler.From between the top of tower and tower bottom in destilling tower 5 Height and position, effluent (liquid or gas) can also be extracted continuously to route 34.

It is more compared with the above-mentioned bottom product from destilling tower 5 from the steam that the top of tower of destilling tower 5 extracts Include the ingredient (low boiling point component) that boiling point is lower than acetic acid, including for example: iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, Dimethyl ether, methanol, acetaldehyde and formic acid etc..Such steam is continuously directed into condenser 5a by route 33.

Condenser 5a by will the steam from destilling tower 5 is cooling make its partial condensation, thus be divided into condensation ingredient and Gas componant.It is condensed into point including, for example, water and acetic acid etc..The a part for condensing ingredient is continuous by route 35 from condenser 5a Ground is back to destilling tower 5.The other parts for condensing ingredient are continuously directed into from condenser 5a by route 35,36,23 Reactive tank 1 and recycled.In addition, the gas componant generated in condenser 5a is including, for example, carbon monoxide, hydrogen, methane, two Carbonoxide, nitrogen, oxygen, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, dimethyl ether, methanol, acetaldehyde and formic acid etc., from condenser 5a is supplied to washing system 8 by route 37,15.It should be noted that as described above, carrying out the gas componant of condenser 5a It can also not conform to and flow to route 15 and be supplied to washing system 8.The hydrogen iodide reached in the gas componant of washing system 8 is being washed It washs system 8 to be absorbed by liquid absorption, iodomethane is generated with methanol or reacting for methyl acetate by the hydrogen iodide in absorbing liquid, so Afterwards, liquid component (tower top stream from 84 tower top of destilling tower) containing useful components such as the iodomethane from washing system 8 via Recirculation circuit 48,23 is recirculated to reactive tank 1 and is recycled.

In the bottom product (or effluent) extracted from the tower bottom of destilling tower 5, with the above-mentioned tower from destilling tower 5 It includes ingredient (higher boiling ingredient) of the boiling point higher than acetic acid, including such as acetic anhydride, propionic acid, acetic acid that top stream, which is compared more, Salt and from potassium iodide, the iodide salts such as iodate metal salt of corrosion metal etc. and entrainment above-mentioned catalyst, help Catalyst etc..It can be mentioned, for example second from the alkali such as potassium hydroxide to route 27 etc. that formed in the case where having supplied for above-mentioned acetate The acetic acid metal salt such as sour potassium.In addition, can also enumerate by the free of the inner wall generation of the member of formation in the acetic acid preparation facilities Metal etc. corrodes the acetic acid metal salt that metal etc. is formed with acetic acid.Above-mentioned iodide salt it can be mentioned, for example: supplied to route 27 Deng The potassium iodide formed in the case where having given the alkali such as potassium hydroxide.It also may include acetic acid in the bottom product.Such bottom product Become the 2nd acetic acid stream via route 34 and is continuously imported subsequent destilling tower 6.In addition, being mentioned from the tower bottom of destilling tower 5 The bottom product (or effluent) taken is also comprising above-mentioned corrosion metal etc. and the iodine by being originated from corrosivity iodine and the corrosion metal etc. The compound (iodide salt) of formation.In the present embodiment, such bottom product is discharged to outside acetic acid preparation facilities.

Compared with the 1st acetic acid stream for continuously being imported destilling tower 5, acetic acid is more enriched with 2nd acetic acid stream.That is, the 2nd acetic acid stream Acetic acid concentration be higher than the 1st acetic acid stream acetic acid concentration.The acetic acid concentration of 2nd acetic acid stream is dense in the acetic acid for being higher than the 1st acetic acid stream In the range of degree, for example, 99.1~99.99 mass %.In addition, as described above, also being wrapped other than acetic acid in the 2nd acetic acid stream Containing such as propionic acid, hydrogen iodide etc..In the present embodiment, in the case where extracting effluent, the extraction of the effluent from destilling tower 5 Position is in the short transverse of destilling tower 5, lower than the importing position for importing the 1st acetic acid stream to destilling tower 5.

In the 2nd acetic acid stream of current through line 34, it can supply or add by route 56 (potassium hydroxide importing route) Add potassium hydroxide.Potassium hydroxide can be supplied or be added with solution forms such as such as aqueous solutions.By being supplied to the 2nd acetic acid stream Or addition potassium hydroxide, it is possible to reduce the hydrogen iodide in the 2nd acetic acid stream.Specifically, hydrogen iodide reacted with potassium hydroxide and Generate potassium iodide and water.Thus, it is possible to reduce as hydrogen iodide and caused by the devices such as destilling tower corrosion.

Destilling tower 6 is unit for carrying out the 3rd distillation process, be considered as in the present embodiment it is so-called take off it is high boiling Tower.3rd distillation process is for second to be further purified after carrying out purification process to the 2nd acetic acid stream for continuously importing destilling tower 6 The process of acid.

Destilling tower 6 includes the rectifying column such as column plate tower and packed column.Using the case where column plate tower is as destilling tower 6 Under, theoretical cam curve is such as 5~50 layers, and according to theoretical cam curve difference, reflux ratio is, for example, 0.2~3000.Exist In the inside of the destilling tower 6 of the 3rd distillation process, tower top pressure is set as such as -100~150kPaG, tower bottom pressure is set For higher than tower top pressure, for example, -90~180kPaG.In the inside for the destilling tower 6 for being present in the 3rd distillation process, by tower top temperature Degree is set as 50~150 DEG C of temperature for example higher than the boiling point of the water under setting tower top pressure and the boiling point lower than acetic acid, by tower Bottom temperature is set as 70~160 DEG C of temperature for example higher than the boiling point of the acetic acid under setting tower bottom pressure.

From the top of tower of destilling tower 6, the steam as tower top stream is continuously extracted to route 38.From the tower of destilling tower 6 Bottom, bottom product are continuously extracted to route 39.6b is reboiler.From between the top of tower and tower bottom in destilling tower 6 Height and position, effluent (liquid or gas) continuously extracted to route 46.In the short transverse of destilling tower 6, route 46 Link position relative to destilling tower 6 can be the such top in route 34 relative to the link position of destilling tower 6 of diagram, It may also be the lower section in route 34 relative to the link position of destilling tower 6, it can also be with route 34 relative to destilling tower 6 Link position is identical.

It is more compared with the above-mentioned bottom product from destilling tower 6 from the steam that the top of tower of destilling tower 6 extracts Include boiling point be lower than acetic acid ingredient (low boiling point component), other than acetic acid, further include for example, iodomethane, hydrogen iodide, Water, methyl acetate, dimethyl ether, methanol and formic acid etc..Such steam is continuously imported condenser 6a by route 38.

Condenser 6a by will the steam from destilling tower 6 is cooling make its partial condensation, thus be divided into condensation ingredient and Gas componant.Ingredient is condensed other than acetic acid, also including, for example, iodomethane, hydrogen iodide, water, methyl acetate, dimethyl ether, first Alcohol and formic acid etc..About at least part of condensation ingredient, distillation is continuously back to from condenser 6a by route 40 Tower 6.About a part (distillating ingredient) of condensation ingredient, can be recirculated to from condenser 6a by route 40,41,42 To destilling tower 5 import before route 27 in the 1st acetic acid stream and can recycle.At the same time or instead, about condensation Partial a part (distillating ingredient) can pass through route 40,41,43 from condenser 6a, and be recirculated to and import destilling tower 3 The vapor stream in route 21 before.

In addition, a part (distillating ingredient) about condensation portion, can pass through route 40,44,23 again from condenser 6a It is recycled to reactive tank 1.Further, it about a part for distillating ingredient for carrying out condenser 6a, can be supplied to as previously mentioned It is used in the system as absorbing liquid to washing system 8.In washing system 8, the gas after useful component is absorbed Ingredient is discharged to outside device, and in turn, the liquid component (tower top stream from 84 tower top of destilling tower) comprising useful component is from washing System 8 is washed to be imported into or be recycled to reactive tank 1 by recirculation circuit 48,23 and recycled.In addition, self cooling about coming A part for distillating ingredient of condenser 6a can be oriented to various pumps (the diagram province operated in the device by the route outside figure Slightly) and the sealing fluid as the pump uses.Further, about a part for distillating ingredient for carrying out condenser 6a, can pass through It is attached to the extraction route of route 40 and is constantly extracted to outside device, can also be extracted if necessary in the form of unsteadiness To outside device.

In the case that a part (distillating ingredient) of condensation portion is removed from the distillation system for handling of destilling tower 6, Its amount for distillating ingredient (quantity of distillate) be the condenser 6a condensate liquid generated such as 0.01~30 mass %, preferably 0.1~ 10 mass %, more preferable 0.3~5 mass %, more preferable 0.5~3 mass %.On the other hand, the gas generated in condenser 6a Ingredient is including, for example, carbon monoxide, hydrogen, methane, carbon dioxide, nitrogen, oxygen, iodomethane, hydrogen iodide, water, methyl acetate, acetic acid, two Methyl ether, methanol, acetaldehyde and formic acid etc. are supplied to washing system 8 from condenser 6a by route 45,15.It should be noted that It flow to route 15 as described above, the gas componant for carrying out condenser 6a can not conform to but is supplied to washing system 8.

In the bottom product being extracted from the tower bottom of destilling tower 6 by route 39, and from the above-mentioned of destilling tower 6 It includes ingredient (higher boiling ingredient) of the boiling point higher than acetic acid, including such as acetate, acetic anhydride, propionic acid that tower top stream, which is compared more, Deng.It can be mentioned, for example potassium acetates from the alkali such as potassium hydroxide to route 34 etc. that formed in the case where having supplied for above-mentioned acetate.Separately Outside, it can also enumerate by corrosion metals such as the free metal of inner wall generation of the member of formation in the acetic acid preparation facilities etc. and second The acetic acid metal salt that acid is formed.The bottom product being extracted from the tower bottom of destilling tower 6 via route 39 further also includes: on State the compound of corrosion metal etc. and the formation such as the iodine by being originated from corrosivity iodine and the corrosion metal.In the present embodiment, Such bottom product is discharged to outside acetic acid preparation facilities.

The effluent for being continuously extracted into route 46 from destilling tower 6 is continuously directed into subsequent as the 3rd acetic acid stream Exchange resin tower 7.Compared with the 2nd acetic acid stream for continuously being imported destilling tower 6, acetic acid is more enriched with 3rd acetic acid stream. That is, the acetic acid concentration of the 3rd acetic acid stream is higher than the acetic acid concentration of the 2nd acetic acid stream.The acetic acid concentration of 3rd acetic acid stream is being higher than the 2nd second In the range of the acetic acid concentration of acid stream, for example, 99.8~99.999 mass %.In the present embodiment, from destilling tower 6 The extraction position of effluent, in the short transverse of destilling tower 6, higher than the importing position that the 2nd acetic acid flows to destilling tower 6.At other In embodiment, the extraction position of the effluent from destilling tower 6, in the short transverse of destilling tower 6, be lower than or with the 2nd second The importing position that acid flows to destilling tower 6 is identical.It should be noted that destilling tower 6 can be replaced with single entry distiller (evaporator), In addition, if can sufficiently remove impurity with destilling tower 5, then destilling tower 6 can be omitted.

Exchange resin tower 7 is the purification unit for carrying out being adsorbed and removed process.This be adsorbed and removed process be for Will continuously be fed in the 3rd acetic acid stream of exchange resin tower 7 it is micro include mainly idoalkane (for example, iodine second Alkane, iodopropane, iodobutane, iodohexane, iodine decane etc.) be adsorbed and removed and process that acetic acid is further purified.

In exchange resin tower 7, filled into tower to the ion exchange resin that idoalkane has adsorption capacity and shape At ion exchange resin bed.As such ion exchange resin, it can be mentioned, for example: as the sulfonic group of cation exchange groups, carboxyl, A part cation exchange resin made of the metal replacements such as silver, copper of property of leaving away in phosphonic acid base etc..It is removed in absorption It goes in process, such as makes the 3rd acetic acid stream (liquid) in the exchange resin tower 7 filled with such ion exchange resin Portion's circulation, in the process of circulation, the impurity absorptions such as idoalkane in the 3rd acetic acid stream are in ion exchange resin and by from the 3rd second Acid stream removes.In being present in the exchange resin tower 7 for being adsorbed and removed process, internal temperature is such as 18~100 DEG C, acetic acid Logical liquid speed degree [the every 1m of resin volume of stream³Acetic acid treatment amount (m³/ h)] it is such as 3~15m³/h·m³(resin volume).

The 4th acetic acid stream continuously is exported to route 47 from the lower end of exchange resin tower 7.The acetic acid of 4th acetic acid stream Concentration is higher than the acetic acid concentration of the 3rd acetic acid stream.That is, the 4th acetic acid stream and the 3rd second for continuously being imported exchange resin tower 7 Sour stream is compared, and acetic acid is more enriched with.The acetic acid concentration of 4th acetic acid stream is within the scope of the acetic acid concentration for being higher than the 3rd acetic acid stream, for example, 99.9~99.999 mass % or its more than.In this preparation method, the 4th acetic acid stream can be stored in the product outside figure Tank.

In the acetic acid preparation facilities, as further to above-mentioned 4th acetic acid stream from exchange resin tower 7 So-called product tower or finishing column as destilling tower can be set in the purification unit purified.Such product tower is being set In the case where, the product tower is including, for example, rectifying columns such as column plate tower and packed columns.Using column plate tower as product tower in the case where, Its theoretical cam curve is such as 5~50 layers, and according to theoretical cam curve difference, reflux ratio is, for example, 0.5~3000.In purification procedures In product tower inside, tower top pressure is for example set as -195~150kPaG, tower bottom pressure is set higher than tower top pressure Power, for example, -190~180kPaG.In the inside of product tower, tower top temperature is for example set higher than under setting tower top pressure Water boiling point and lower than 50~150 DEG C of temperature of boiling point of acetic acid, column bottom temperature is set as example higher than setting tower bottom pressure 70~160 DEG C of the temperature of the boiling point of acetic acid under power.It should be noted that product tower or finishing column can also be distilled with single entry Device (evaporator) replaces.

In the case where product tower is arranged, the whole of the 4th acetic acid stream (liquid) from exchange resin tower 7 or one Divide and is continuously directed into product tower.From the top of tower of such product tower, as containing micro low boiling point component (for example, Iodomethane, water, methyl acetate, dimethyl ether, crotonaldehyde, acetaldehyde and formic acid etc.) the steam of tower top stream continuously extracted.The steaming Gas is divided into the condensation gentle body ingredient of ingredient with given condenser.

A part of condensation ingredient is continuously back to product tower, and the other a part for condensing ingredient are circulated to instead It answers slot 1 or discards to outside system or both can be, gas componant is supplied to washing system 8.From product tower Tower bottom, the bottom product containing micro higher boiling ingredient are continuously extracted, which, which is recycled to, is for example leading Enter the 2nd acetic acid stream in the route 34 before destilling tower 6.Height and position between the top of tower and tower bottom in product tower, Effluent (liquid) is continuously extracted as the 5th acetic acid stream.For the extraction position of the effluent from product tower, in product in tower Short transverse on, such as it is lower than the importing position that the 4th acetic acid flows to product tower.

For the 5th acetic acid stream, compared with the 4th acetic acid stream for being continuously directed into product tower, acetic acid is more enriched with.That is, the 5th The acetic acid concentration of acetic acid stream is higher than the acetic acid concentration of the 4th acetic acid stream.The acetic acid concentration of 5th acetic acid stream is being higher than the 4th acetic acid stream Within the scope of acetic acid concentration, for example, 99.9~99.999 mass % or its more than.5th acetic acid stream can be for example stored in outside figure Product tank.It should be noted that the alternative solution for exchange resin tower 7, as the downstream for being set to destilling tower 6 (or other than the downstream in addition to being set to destilling tower 6 also), it can also be set to the downstream of product tower, to own product tower out Acetic acid stream is handled.