阅读说明：本技术 一种利用曼海姆炉尾气生产试剂盐酸的方法及生产系统 (Method and production system for producing reagent hydrochloric acid by using Mannheim furnace tail gas ) 是由 吴军祥 吴良毅 孙汉勇 石建华 王秀萍 夏涛 索振华 王林浩 于 2021-08-04 设计创作，主要内容包括：本发明提供一种利用曼海姆炉尾气生产试剂盐酸的方法及生产系统,包括如下步骤：曼海姆炉排出的尾气进入硫酸洗涤塔,用浓硫酸吸收杂质气体,硫酸洗涤塔排出的气体经过依次经过一级洗涤塔、一级过滤器、二级洗涤塔、三级洗涤塔、二级过滤器,且所述三级洗涤塔的下部通过液相管道与二次洗涤塔连通,使得三级洗涤塔通过管道向二级洗涤塔中补液,同时所述二级洗涤塔外部的循环通道上加装有换热器,换热器与冷冻机连通,冷冻机将换热器的循环水降温至低于5℃。在低温下,在二级洗涤塔中的循环水能够一直循环吸收氯化氢气体,使得最后的盐酸浓度能达到接近36%,提高对氯化氢气体的吸收能力,进而提高最终得到的试剂盐酸的浓度。(The invention provides a method and a production system for producing reagent hydrochloric acid by using Mannheim furnace tail gas, comprising the following steps of: the tail gas discharged by the Mannheim furnace enters a sulfuric acid washing tower, the concentrated sulfuric acid is used for absorbing impurity gas, the gas discharged by the sulfuric acid washing tower sequentially passes through a primary washing tower, a primary filter, a secondary washing tower, a tertiary washing tower and a secondary filter, the lower part of the tertiary washing tower is communicated with the secondary washing tower through a liquid phase pipeline, so that the tertiary washing tower replenishes liquid into the secondary washing tower through the pipeline, meanwhile, a heat exchanger is additionally arranged on a circulating channel outside the secondary washing tower and is communicated with a refrigerator, and the refrigerator cools the circulating water of the heat exchanger to be lower than 5 ℃. At low temperature, the circulating water in the secondary washing tower can circularly absorb the hydrogen chloride gas all the time, so that the final hydrochloric acid concentration can reach nearly 36%, the absorption capacity of the hydrogen chloride gas is improved, and the concentration of the finally obtained reagent hydrochloric acid is further improved.)

1. A method for producing reagent hydrochloric acid by using Mannheim furnace tail gas is characterized by comprising the following steps: the tail gas discharged by the Mannheim furnace enters a sulfuric acid washing tower, the concentrated sulfuric acid is used for absorbing impurity gas, the gas discharged by the sulfuric acid washing tower sequentially passes through a primary washing tower, a primary filter, a secondary washing tower, a tertiary washing tower and a secondary filter, the lower part of the tertiary washing tower is communicated with the secondary washing tower through a liquid phase pipeline, so that the tertiary washing tower replenishes liquid into the secondary washing tower through the pipeline, meanwhile, a heat exchanger is additionally arranged on a circulating channel outside the secondary washing tower and is communicated with a refrigerator, and the refrigerator cools the circulating water of the heat exchanger to be lower than 5 ℃.

2. The method for producing the reagent hydrochloric acid by using the Mannheim furnace tail gas as claimed in claim 1, wherein the inside of the primary filter is provided with glass fiber at the front end and activated carbon at the rear end for filtering organic substances and metal ions.

3. The method for producing reagent hydrochloric acid using mannheimer exhaust gas as claimed in claim 2, wherein said secondary filter uses a resin tank for filtering metal ions.

4. The method for producing reagent hydrochloric acid by using Mannheim exhaust gas according to claim 1, wherein the primary filter is internally provided with glass fiber and expanded graphite.

5. The method for producing the reagent hydrochloric acid by using the Mannheim exhaust gas as claimed in claim 4, wherein chitosan is loaded on the surface of the expanded graphite.

6. The method for producing the reagent hydrochloric acid by using the Mannheim furnace tail gas as claimed in claim 5, wherein the preparation method of the expanded graphite comprises the following steps:

and (2) putting the spare expanded graphite into 32% hydrochloric acid solution, stirring, filtering, washing, drying at 105 ℃, slowly dissolving chitosan by using water to prepare chitosan solution, slowly adding the dried expanded graphite into the chitosan solution, stirring to fully and uniformly mix the chitosan solution, and drying at 110 ℃ for 6 hours to obtain the chitosan/expanded graphite adsorbent.

7. The method for producing the reagent hydrochloric acid by using the Mannheim exhaust gas as claimed in claim 6, wherein the mass ratio of the chitosan to the expanded graphite is 1: 20.

8. The method for producing reagent hydrochloric acid by using mannheimer's off-gas according to claim 1, wherein the primary washing tower, the secondary washing tower, and the tertiary washing tower are all washed with pure water.

9. The method for producing reagent hydrochloric acid by using Mannheim furnace tail gas as claimed in claim 1, wherein concentrated sulfuric acid is pumped into a spray header near the top of the tower by using a P105 circulating pump in the sulfuric acid washing tower, so as to form an in-tower circulation.

10. A production system for producing reagent hydrochloric acid by using mannheim furnace tail gas, which is characterized in that the method of any one of claims 1 to 9 is used, the production system comprises a mannheim furnace, a sulfuric acid washing tower, a primary filter, a secondary washing tower, a tertiary washing tower and a secondary filter, wherein the input end of the sulfuric acid washing tower is connected with the mannheim furnace, the output end of the sulfuric acid washing tower is connected with the primary washing tower, the output end of the primary washing tower is connected with the primary filter, and the secondary washing tower, the tertiary washing tower and the secondary filter are sequentially arranged after the primary filter.

Technical Field

The invention relates to the field of production of electronic chemical reagents, in particular to a method and a production system for producing reagent hydrochloric acid by using Mannheim furnace tail gas.

Background

With the rapid development of semiconductor technology, the requirement for ultra-clean and high-purity reagents is higher and higher. In the process of processing Integrated Circuits (IC), the ultra-clean high-purity reagent is mainly used for cleaning and etching the surfaces of chips and silicon wafers, and the purity and cleanliness of the ultra-clean high-purity reagent have great influence on the yield, the electrical property and the reliability of the integrated circuits. The ultra-clean reagent hydrochloric acid is widely used in the aspects of cleaning, drying and the like in the processing process of semiconductors and large-scale integrated circuits as an important microelectronic chemical.

At present, the production technology mainly adopted for producing the electronic chemical reagent hydrochloric acid is a rectification method. For example, a patent with publication number of CN103213947B in the prior art discloses a process for producing reagent hydrochloric acid by using a rectification method, which comprises the steps of selecting materials, and selecting a hydrochloric acid solution with the concentration of 36-38% as a raw material; diluting, namely diluting the raw material to 35% by using deionized water; rectifying, namely adding the diluted raw material into internally heated rectifying equipment, introducing cooling water into a hydrochloric acid absorber, and starting an internal heating device to heat the raw material; absorbing, namely heating and evaporating the raw materials to generate gaseous hydrochloric acid and water vapor, then reforming the gaseous hydrochloric acid and the water vapor into a hydrochloric acid solution in a hydrochloric acid absorber through a pipeline, continuously adding the raw materials into the rectifying equipment at the moment, and simultaneously opening a slag discharge valve; blending, namely pumping the hydrochloric acid solution into a mixing tank, and performing blending treatment in the mixing tank, wherein the blending treatment is controlled to be about 37%; and (3) filtering and subpackaging, namely filtering the assembled hydrochloric acid solution through a filter to obtain a finished hydrochloric acid solution, and then subpackaging. Although the method can prepare hydrochloric acid with higher purity, the method has the following defects: firstly, resistance wire tube type heating is adopted during heating, so that the energy consumption is high, and the heat conduction efficiency is influenced by the scale on the inner surface of the tube due to long-time heating inside the tube, and the danger is easily generated; secondly, the yield is low, crude hydrochloric acid forms about 18 percent (the proportion of hydrogen chloride and water is constant) azeotrope when being heated at 112 ℃ in a tower kettle, raw materials are continuously added into the tower in continuous production, residual liquid is continuously discharged, the content of hydrogen chloride in the discharged residual liquid is nearly 20 percent, the yield is only about 60 percent, the discharged residual liquid causes environmental pollution, and great burden is brought to environmental protection facilities.

Along with increasingly outstanding environmental protection problems and increasing call for energy conservation and emission reduction in the field of chemical production, a patent with publication number of CN110127615A in the prior art discloses an online purification method for hydrochloric acid generated in the process of producing potassium sulfate by using a Mannheim furnace, wherein gas discharged from the Mannheim furnace is cooled by a cooler, and then enters a first-stage washing tower, a second-stage washing tower, a third-stage falling film absorption tower and a fourth-stage washing tower in sequence and is discharged; washing liquid obtained by washing and absorbing the environment-friendly tail gas by deionized water sequentially enters a second-stage washing tower and a first-stage washing tower to be washed, and finally hydrochloric acid B is obtained, the hydrochloric acid B enters a distillation tower to be distilled, distilled fractions are cooled to obtain food-grade hydrochloric acid, the deionized water washes hydrogen chloride gas in a fourth-stage washing tower, the hydrogen chloride gas enters a third-stage falling film absorption tower to be absorbed, and gas distilled by the distillation tower enters a third-stage falling film absorption tower to be absorbed to obtain hydrochloric acid A; the heat required by the distillation tower is provided by tail gas generated by a combustion chamber which provides heat for the Mannheim furnace. Although the tail gas discharged by the Mannheim furnace is effectively utilized in the prior art, the hydrochloric acid obtained after passing through the washing tower still needs to enter the distillation tower for distillation, the requirement on equipment materials, namely a heat supply mode, is high, and investigation research shows that most enterprises adopt small equipment and multiple sets of production when utilizing the method to produce the hydrochloric acid, so that the preparation of operators is less, and great potential safety hazards exist.

Disclosure of Invention

In view of the above, the present invention aims to provide a method and a system for producing reagent hydrochloric acid by using mannheim furnace off-gas, so as to solve the problems of high energy consumption, low yield and small production scale in the production of reagent hydrochloric acid in the prior art.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for producing reagent hydrochloric acid by using Mannheim furnace tail gas comprises the following steps: the tail gas discharged by the Mannheim furnace enters a sulfuric acid washing tower, the concentrated sulfuric acid is used for absorbing impurity gas, the gas discharged by the sulfuric acid washing tower sequentially passes through a primary washing tower, a primary filter, a secondary washing tower, a tertiary washing tower and a secondary filter, the lower part of the tertiary washing tower is communicated with the secondary washing tower through a liquid phase pipeline, so that the tertiary washing tower replenishes liquid into the secondary washing tower through the pipeline, meanwhile, a heat exchanger is additionally arranged on a circulating channel outside the secondary washing tower and is communicated with a refrigerator, and the refrigerator cools the circulating water of the heat exchanger to be lower than 5 ℃. At low temperature, the circulating water in the secondary washing tower can circularly absorb the hydrogen chloride gas all the time, so that the final hydrochloric acid concentration can reach nearly 36%, the absorption capacity of the hydrogen chloride gas is improved, and the concentration of the finally obtained reagent hydrochloric acid is further improved.

Furthermore, glass fiber is placed at the front end inside the primary filter, and activated carbon is placed at the rear end of the primary filter for filtering out organic matters and metal ions.

Further, the secondary filter adopts a resin tank for filtering metal ions.

Furthermore, glass fiber and expanded graphite are placed inside the primary filter. The expanded graphite has good adsorption and removal capacity on metal ions, and the content of metal ions such as iron and copper in the finally obtained reagent hydrochloric acid is effectively reduced.

Further, chitosan is loaded on the surface of the expanded graphite.

Further, the preparation method of the expanded graphite comprises the following steps: and (2) putting the spare expanded graphite into 32% hydrochloric acid solution, stirring, filtering, washing, drying at 105 ℃, slowly dissolving chitosan by using water to prepare chitosan solution, slowly adding the dried expanded graphite into the chitosan solution, stirring to fully and uniformly mix the chitosan solution, and drying at 110 ℃ for 6 hours to obtain the chitosan/expanded graphite adsorbent.

Further, the mass ratio of the chitosan to the expanded graphite is 1: 20.

Further, the first-stage washing tower, the second-stage washing tower and the third-stage washing tower are washed by pure water.

Furthermore, concentrated sulfuric acid is pumped into a spray header near the top of the tower in the sulfuric acid washing tower by using a P105 circulating pump, so that an in-tower circulation is formed.

The invention also provides a production system for producing reagent hydrochloric acid by using the Mannheim furnace tail gas, which comprises the method, wherein the production system comprises a Mannheim furnace, a sulfuric acid washing tower, a primary filter, a secondary washing tower, a tertiary washing tower and a secondary filter, the input end of the sulfuric acid washing tower is connected with the Mannheim furnace, the output end of the sulfuric acid washing tower is connected with the primary washing tower, the output end of the primary washing tower is connected with the primary filter, and the secondary washing tower, the tertiary washing tower and the secondary filter are sequentially arranged behind the primary filter.

Compared with the prior art, the method for producing the reagent hydrochloric acid by using the Mannheim furnace tail gas has the following advantages:

the invention adds the first filter and the second filter to filter gas phase or hydrochloric acid solution hydrochloric acid in the production process of the reagent hydrochloric acid for many times, and can obtain high-purity reagent hydrochloric acid without distillation, thereby overcoming various weaknesses in the production of the reagent hydrochloric acid by a rectification method and realizing continuous large-scale production.

The method has low energy consumption and high yield, can be used for large-scale production, can use most of byproducts as industrial raw materials of other production processes, realizes the production of high-purity and high-concentration (36-38%) hydrochloric acid by a gas absorption method, and overcomes the defect that only 31-32% hydrochloric acid can be produced by the traditional gas absorption method.

The adopted raw materials are byproducts of the potassium sulfate production process by using a Mannheim furnace, the price is high, about 38 percent of reagent hydrochloric acid is produced in a large amount by two times of absorption and filtration, the production cost is reduced, and the byproducts are used as the raw materials of other production processes, so that the energy consumption is reduced.

Drawings

FIG. 1 is a production system for producing reagent hydrochloric acid according to an embodiment of the present invention;

FIG. 2 is a first washing and a first filtering process in a process for producing reagent hydrochloric acid according to an embodiment of the present invention;

FIG. 3 is a second washing process in the process for producing reagent hydrochloric acid according to an embodiment of the present invention;

FIG. 4 is a three-stage washing process in a process for producing reagent hydrochloric acid according to an embodiment of the present invention;

FIG. 5 shows a second stage filtration process in the process for producing reagent hydrochloric acid according to an embodiment of the present invention.

Description of reference numerals:

mannheim furnace 1, sulfuric acid washing tower 2, fourth gas inlet 21, fourth body outlet 22, primary washing tower 3, first gas inlet 31, first gas outlet 32, first circulating pump 33, first liquid phase outlet 34, second circulating pump 35, primary filter 4, secondary washing tower 5, second gas inlet 51, second gas outlet 52, second liquid phase outlet 53, third circulating pump 54, heat exchanger 55, refrigerator 56, tertiary washing tower 6, third gas inlet 61, third gas outlet 62, fourth circulating pump 63, third liquid phase outlet 64, secondary filter 7, tail gas treatment tower 8.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

A method for producing reagent hydrochloric acid by using Mannheim furnace tail gas comprises the following steps: the tail gas discharged by the Mannheim furnace enters a sulfuric acid washing tower, the concentrated sulfuric acid is used for absorbing impurity gas, the gas discharged by the sulfuric acid washing tower sequentially passes through a primary washing tower, a primary filter, a secondary washing tower, a tertiary washing tower and a secondary filter, the lower part of the tertiary washing tower is communicated with the secondary washing tower through a liquid phase pipeline, so that the tertiary washing tower replenishes liquid into the secondary washing tower through the pipeline, meanwhile, a heat exchanger is additionally arranged on a circulating channel outside the secondary washing tower and is communicated with a refrigerator, and the refrigerator cools the circulating water of the heat exchanger to be lower than 5 ℃.

Furthermore, glass fiber is placed at the front end inside the primary filter, and activated carbon is placed at the rear end of the primary filter for filtering out organic matters and metal ions.

Further, the secondary filter adopts a resin tank for filtering metal ions.

Furthermore, glass fiber and expanded graphite are placed inside the primary filter.

Further, chitosan is loaded on the surface of the expanded graphite.

Further, the preparation method of the expanded graphite comprises the following steps: and (2) putting the spare expanded graphite into 32% hydrochloric acid solution, stirring, filtering, washing, drying at 105 ℃, slowly dissolving chitosan by using water to prepare chitosan solution, slowly adding the dried expanded graphite into the chitosan solution, stirring to fully and uniformly mix the chitosan solution, and drying at 110 ℃ for 6 hours to obtain the chitosan/expanded graphite adsorbent.

Further, the mass ratio of the chitosan to the expanded graphite is 1: 20.

Further, the first-stage washing tower, the second-stage washing tower and the third-stage washing tower are washed by pure water.

Furthermore, concentrated sulfuric acid is pumped into a spray header near the top of the tower in the sulfuric acid washing tower by using a P105 circulating pump, so that an in-tower circulation is formed.

Example 1

As shown in fig. 1 to 5, the embodiment provides a method for producing reagent hydrochloric acid by using mannheim furnace off-gas, which specifically includes the following steps:

(1) m101 Mannheim furnace tail gas treatment: absorbing impurity gas by concentrated sulfuric acid

After potassium chloride + concentrated sulfuric acid → potassium sulfate + hydrogen chloride gas react in a Mannheim furnace, the gas impurities contain nitrogen oxides, metal salts, sulfides, iron ions, organic substances VOC, carbon oxides, bromine ions and the like, the hydrogen chloride gas accounts for about 32% -42% of the gas impurities, the tail gas is used as a raw material for producing reagent hydrochloric acid, the tail gas is guided into a sulfuric acid washing tower T104 by P106 and then enters the sulfuric acid washing tower T104 from the lower part of the sulfuric acid washing tower T104, the concentrated sulfuric acid is pumped into a spray header near the top of the tower in the tower by a P105 circulating pump to form an inner circulation of the tower, and the concentrated sulfuric acid is used for absorbing the impurity gases.

(2) First stage washing

Then, the gas is introduced into a first-stage washing tower T101 by a fan P101, a certain amount of pure water is introduced into the first-stage washing tower T101 in advance, the pure water is sprayed down from the upper part in the first-stage washing tower by a circulating pump P102 through a spray header, impurity gases capable of being dissolved in water and a certain amount of hydrogen chloride gas are absorbed, the rest gas is discharged from the top of the tower, and when the concentration of hydrochloric acid in the liquid in the first-stage washing tower T101 exceeds 31%, the liquid is collected by the pump and can be used as a raw material for analyzing the hydrochloric acid by an analyzing tower.

(3) First stage filtration

The exhausted gas passes through a primary filter G101, glass fiber is placed at the front end of the interior of the primary filter G, activated carbon is placed at the rear end of the primary filter G for filtering, and organic matters and part of metal ions in the gas are filtered.

(4) Two stage washing

Introducing pure water with the conductivity of less than 2.0us/cm into a secondary washing tower T102 at the flow rate of 0.25T/h in advance, beating the pure water to a spray header at the top of the tower by using a circulating pump P103 to carry out hydrogen chloride absorption operation, additionally arranging a heat exchanger E101 on a circulating channel, cooling the circulating water to about 5 ℃ by using a refrigerator E102, and introducing the circulating water into the E101 to cool the circulating material of the secondary washing tower T102; experiments prove that at low temperature, hydrogen chloride gas is circularly absorbed in the secondary washing tower T102 all the time, and the final hydrochloric acid concentration can reach approximately 36%; the residual gas which is not absorbed enters a third-stage washing tower T103 through the tower top to be subjected to third-stage washing;

(5) three-stage washing

In the third-stage washing tower T103, the circulating pump P104 is also adopted to enable pure water to reach the top of the tower, the pure water is sprayed through the spray header to absorb redundant hydrogen chloride gas, the pure water of the pure water mechanism enters the third-stage washing tower T103 through the circulating pump, the third-stage washing tower T103 is communicated with the second-stage washing tower T102 through a pipeline, and therefore liquid supplement is facilitated for the second-stage washing tower T102. Meanwhile, gas discharged from the T103 enters a tail gas absorption tower;

(6) two stage filtration

Through tests, the index concentration of the T102 tower meets the requirement, and the index concentration is reached into the S101 resin tank by using the circulating pump P103, and the resin tank is used for filtering metal ions.

Finally, high-purity reagent hydrochloric acid is obtained and stored in a finished product tank.

Example 2

The process for producing reagent hydrochloric acid in this example is the same as in example 1, except that: (3) glass fiber and modified expanded graphite filling are placed in a first filter G101 in primary filtration, and the preparation method of the expanded graphite comprises the following steps:

and (2) putting the spare expanded graphite into 32% hydrochloric acid solution, stirring, filtering, washing, drying at 105 ℃, and slowly dissolving chitosan by using water to prepare chitosan solution. And slowly adding the dried expanded graphite into the chitosan solution, stirring to fully and uniformly mix the expanded graphite and the chitosan solution, and drying at the temperature of 110 ℃ for 6 hours to obtain the chitosan/expanded graphite adsorbent. Wherein the mass ratio of the chitosan to the expanded graphite is 1: 20.

Example 3

The process for producing reagent hydrochloric acid in this example is the same as example 2, except that: (6) the S101 resin tank of the secondary-secondary filter is filled with adsorption resin, the surface of the adsorption resin is loaded with beta-cyclodextrin, and the adsorption resin enables the beta-cyclodextrin to be loaded in a polyurethane cross-linked network through polymerization reaction under the action of a catalyst, namely the beta-cyclodextrin, polyol, isocyanate and a foaming agent, so that the adsorption resin has a good adsorption effect on organic matters and metal ions.

Specifically, the preparation method of the modified adsorption resin comprises the following steps:

firstly, 2.0g of beta-cyclodextrin is dissolved in water; dissolving 50g of polypropylene glycol, 100g of diphenylmethane diisocyanate, 0.25g of initiator and deionized water to obtain a prepolymer system; wherein the mass ratio of the polypropylene glycol to the diphenylmethane diisocyanate is 1:2, and the initiator adopts stannous octoate. Mixing the beta-cyclodextrin water solution with the prepolymer system at room temperature, adding the mixture into a reactor for reaction and foaming, and curing for 2 hours in a vacuum oven after foaming is finished.

Comparative example 1

(1) M101 Mannheim furnace tail gas treatment: absorbing impurity gas by concentrated sulfuric acid

After potassium chloride + concentrated sulfuric acid → potassium sulfate + hydrogen chloride gas react in a Mannheim furnace, the gas impurities contain nitrogen oxides, metal salts, sulfides, iron ions, organic substances VOC, carbon oxides, bromine ions and the like, the hydrogen chloride gas accounts for about 32% -42% of the gas impurities, the tail gas is used as a raw material for producing reagent hydrochloric acid, the tail gas is guided into a sulfuric acid washing tower T104 by P106 and then enters the sulfuric acid washing tower T104 from the lower part of the sulfuric acid washing tower T104, the concentrated sulfuric acid is pumped into a spray header near the top of the tower in the tower by a P105 circulating pump to form an inner circulation of the tower, and the concentrated sulfuric acid is used for absorbing the impurity gases.

(2) First stage washing

Then, the gas is introduced into a first-stage washing tower T101 by a fan P101, a certain amount of pure water is introduced into the first-stage washing tower T101 in advance, the pure water is sprayed down from the upper part in the first-stage washing tower by a circulating pump P102 through a spray header, impurity gases capable of being dissolved in water and a certain amount of hydrogen chloride gas are absorbed, the rest gas is discharged from the top of the tower, and when the concentration of hydrochloric acid in the liquid in the first-stage washing tower T101 exceeds 31%, the liquid is collected by the pump and can be used as a raw material for analyzing the hydrochloric acid by an analyzing tower.

(3) Two stage washing

Introducing gas exhausted from the top of the first-stage washing tower T101 into a second-stage washing tower T102, introducing pure water with the conductivity of less than 2.0us/cm into the second-stage washing tower T102 at the flow rate of 0.25T/h in advance, beating the pure water to a spray header at the top of the tower by using a circulating pump P103 to carry out hydrogen chloride absorption operation, additionally arranging a heat exchanger E101 on a circulating channel, cooling the circulating water to about 5 ℃ by using a refrigerator E102, and introducing the circulating water into the E101 to cool circulating materials of the second-stage washing tower T102; experiments prove that at low temperature, hydrogen chloride gas is circularly absorbed in the secondary washing tower T102 all the time, and the final hydrochloric acid concentration can reach approximately 36%; the residual gas which is not absorbed enters a third-stage washing tower T103 through the tower top to be subjected to third-stage washing;

(4) three-stage washing

In the third-stage washing tower T103, the circulating pump P104 is also adopted to enable pure water to reach the top of the tower, the pure water is sprayed through the spray header to absorb redundant hydrogen chloride gas, the pure water of the pure water mechanism enters the third-stage washing tower T103 through the circulating pump, the third-stage washing tower T103 is communicated with the second-stage washing tower T102 through a pipeline, and therefore liquid supplement is facilitated for the second-stage washing tower T102. Meanwhile, gas discharged from the T103 enters a tail gas absorption tower;

finally, high-purity reagent hydrochloric acid is obtained and stored in a finished product tank.

Comparative example 2

The comparative example differs from example 1 in the method for producing the reagent hydrochloric acid: there is not liquid pipeline that is linked together between tertiary scrubbing tower and second grade scrubbing tower, in tertiary scrubbing tower T103 promptly, also adopt circulating pump P104 to reach the top of the tower with pure water, spray the pure water through the shower head, absorb unnecessary hydrogen chloride gas to, the pure water of pure water mechanism gets into tertiary scrubbing tower T103 through its circulating pump in, and the gas that tertiary scrubbing tower T103 discharged simultaneously gets into the tail gas absorption tower, and the liquid phase behind tertiary scrubbing tower T103 washing gets into inside the second grade filter and filters.

Test examples

The quality of the hydrochloric acid obtained in the examples 1 to 3 and the comparative examples 1 and 2 is detected, and the percentage contents of the hydrochloric acid, the metal ions and the organic matters are determined, and the specific contents are as follows:

	HCl(％)	Fe3+(％)	Cu2+(％)	sulfate (SO)4 2-,％)	Organics (%)
						Example 1	35.4	0.0011	0.0008	0.013	0.17
Example 2	37.2	0.0007	0.0003	0.008	0.10
						Example 3	37.5	0.0004	0.0003	0.006	0.05
Comparative example 1	32.1	0.0023	0.0017	0.018	0.19
						Comparative example 2	31.3	0.0012	0.0008	0.014	0.13

By comparing example 1 with comparative example 1, it can be found that the concentration of hydrochloric acid can be increased by adding a filter between the first-stage washing tower and the second-stage washing tower and adding a filter after the third-stage washing tower to filter metal ions and nonvolatile organic impurities in the hydrochloric acid.

Through comparison between example 1 and example 2, it can be found that when the chitosan-loaded expanded graphite is used as an adsorbent instead of activated carbon in the primary filter, the content of copper ions in hydrochloric acid is obviously reduced due to the action between chitosan and copper ions, and the expanded graphite has stronger adsorption capacity to organic matters than activated carbon.

By comparing example 2 with example 3, it can be seen that, when the secondary filter is filled with polyurethane supported by beta-cyclodextrin, the hydroxyl groups in beta-cyclodextrin also chemically react with isocyanate groups during the process that isocyanate groups will undergo polymerization reaction with polypropylene glycol to form a polyurethane cross-linked network structure, so that beta-cyclodextrin is fixed in the polyurethane cross-linked network. The beta-cyclodextrin has good absorption effect on organic matters, and meanwhile, the polyurethane cross-linked network forms a filling framework in the secondary filter, so that the hydrochloric acid solution can be fully contacted with the beta-cyclodextrin and the polyurethane when passing through the secondary filter, and the adsorption capacity on the organic matters and metal ions in the hydrochloric acid solution is greatly improved.

Through comparison between the embodiment 1 and the comparative example 2, it can be found that when the hydrochloric acid is washed by the third washing tower and the discharged liquid phase returns to the second washing tower, the liquid is replenished to the second washing tower, and meanwhile, the hydrochloric acid in the second washing tower performs secondary circulation on the gas discharged from the first washing tower to absorb the hydrogen chloride gas, so that the concentration of the hydrochloric acid is greatly improved.

Example 4

The embodiment provides a production system for producing reagent hydrochloric acid by using Mannheim furnace tail gas, which comprises a Mannheim furnace 1, a sulfuric acid washing tower 2, a first-stage washing tower 3, a first-stage filter 4, a second-stage washing tower 5, a third-stage washing tower 6 and a second-stage filter 7, wherein the input end of the sulfuric acid washing tower 2 is connected with the Mannheim furnace 1, the output end of the sulfuric acid washing tower 2 is connected with the first-stage washing tower 3, the output end of the first-stage washing tower 3 is connected with the first-stage filter 4, and the second-stage washing tower 5, the third-stage washing tower 6 and the second-stage filter 7 are sequentially arranged behind the first-stage filter 4.

In this embodiment, a first gas inlet 31 and a first gas outlet 32 are provided on the first-stage washing tower 3, the first gas inlet 31 is provided at a position near the lower portion of the first-stage washing tower 3, the first gas outlet 32 is provided at the top of the first-stage washing tower 3, the first gas inlet 31 is communicated with the sulfuric acid washing tower 2 through a first circulating pump 33, and the first gas outlet 32 is communicated with the first-stage filter 4.

Further, a first liquid phase outlet 34 and a first pure water inlet are further arranged at the lower part of the first-stage washing tower 3, pure water enters the bottom of the first-stage washing tower through the first pure water inlet, and the pure water is sprayed down from the upper part in the first-stage washing tower through the spray header through a second circulating pump 35 after passing through the first liquid phase outlet 34.

In the present embodiment, a second gas inlet 51 and a second gas outlet 52 are provided on the secondary scrubber 5, the first gas inlet 51 is provided at a position near the lower portion of the secondary scrubber 5, and the second gas outlet 52 is provided at the top of the secondary scrubber 5. Pure water is pre-introduced into the second-stage washing tower 5, a second liquid phase outlet 53 and a second liquid phase inlet are also arranged at the lower part of the second-stage washing tower 5, the second liquid phase inlet is connected with the third-stage washing tower 6, and the pure water and the liquid phase from the third-stage washing tower 6 are sprayed down through a spray header at the upper part of the second-stage washing tower 5 by the second liquid phase outlet 53 through a third circulating pump 54 and a circulating channel.

Further, a heat exchanger 55 is provided in the circulation path of the secondary scrubber 5, the heat exchanger 55 is connected to a refrigerator 56, and the refrigerator 56 cools the circulation water in the heat exchanger 55.

Furthermore, the circulating channel is also communicated with a secondary filter 7, and the liquid phase obtained after the hydrogen chloride gas is circularly absorbed in the secondary washing tower 5 is introduced into the secondary filter 7 for filtering, so that the reagent hydrochloric acid is finally obtained.

In the present embodiment, a third gas inlet 61 and a third gas outlet 62 are provided on the third-stage washing tower 6, the third gas inlet 61 is provided at a position near the lower portion of the third-stage washing tower 6, and the third gas outlet 62 is provided at the top of the third-stage washing tower 6. The pure water is sprayed down from the spray header at the upper part of the third-stage washing tower 6 through a fourth circulating pump 63.

Further, a third liquid phase outlet 64 is provided below the third-stage washing tower 6, and the third liquid phase outlet 64 communicates with the second liquid phase inlet of the second-stage washing tower 5.

In this embodiment, the production system of the present invention further includes a tail gas treatment tower 8, and the third gas outlet 62 at the top of the third-stage washing tower 6 is communicated with the tail gas treatment tower 8 of the production system.

In the embodiment, the sulfuric acid washing tower 2 is provided with a fourth gas inlet 21 and a fourth gas outlet 22, the fourth gas inlet 21 is communicated with the Mannheim furnace 1, and the fourth gas outlet 22 is communicated with the primary washing tower 3.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.