阅读说明：本技术 一种光化反应溶剂邻二氯苯的回收提纯设备及其工艺 (Equipment and process for recovering and purifying photochemical reaction solvent o-dichlorobenzene ) 是由 叶长燊 邱挺 王红星 黄智贤 王清莲 王晓达 李玲 杨臣 陈鲤铭 刘影 于 2019-10-25 设计创作，主要内容包括：本发明涉及一种光化反应过程溶剂邻二氯苯的回收提纯设备及其工艺,属于隔壁精馏分离技术领域。含有邻二氯苯、四氯化碳、光气、氯化氢和少量的甲苯二异氰酸酯混合液从隔壁精馏塔隔板左侧中部进入,塔顶采出光气和少量四氯化碳,在隔板右侧中上部侧线采出高纯度的四氯化碳,在塔底列管换热器上部侧线采出邻二氯苯溶剂,塔底采出少量的邻二氯苯和甲苯二异氰酸酯。本发明可将光化反应过程邻二氯苯溶剂有效脱除四氯化碳以及其他杂质,得到高纯度的四氯化碳副产物,并精制得到邻二氯苯,保证其回用时最大限度地削弱对光化反应的不利影响。(The invention relates to equipment and a process for recovering and purifying o-dichlorobenzene serving as a solvent in a photochemical reaction process, and belongs to the technical field of next-door rectification separation. The mixed solution containing o-dichlorobenzene, carbon tetrachloride, phosgene, hydrogen chloride and a small amount of toluene diisocyanate enters from the middle part of the left side of a partition plate of a partition wall rectifying tower, phosgene and a small amount of carbon tetrachloride are collected from the top of the tower, high-purity carbon tetrachloride is collected from the lateral line of the middle upper part of the right side of the partition plate, an o-dichlorobenzene solvent is collected from the lateral line of the upper part of a column tube heat exchanger at the bottom of the tower, and a small amount of o-dichlorobenzene and toluene. The method can effectively remove carbon tetrachloride and other impurities from the o-dichlorobenzene solvent in the photochemical reaction process to obtain a high-purity carbon tetrachloride byproduct, and the o-dichlorobenzene is obtained by refining, so that the adverse effect on the photochemical reaction is weakened to the maximum extent when the o-dichlorobenzene is recycled.)

1. The equipment for recovering and purifying the photochemical reaction solvent o-dichlorobenzene is characterized by comprising the following steps: comprises a bulkhead rectifying tower (T101), a partial condenser (E102) at the top of the tower, a cooler (E103), a carbon tetrachloride product tank (V101), a condenser (E104) and an ortho-dichlorobenzene recycling tank (V102) which are connected with each other through pipelines.

2. The apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent according to claim 1, characterized in that: the middle part of next door rectifying column is provided with baffle (2), and the upper portion of baffle (2) is public rectifying section (3), and the lower part of baffle (2) is public stripping section (4), the left side of baffle (2) is divided into baffle left side upper portion packing layer (5) and baffle left side lower part packing layer (6) by inlet pipe (1), the right side of baffle (2) is divided into baffle right side upper portion packing layer (7) and baffle right side lower part packing layer (8) by side line carbon tetrachloride extraction pipe (12), next door rectifying column top is divided into two tunnel after top of the tower steam pipe (9) is connected to tower top partial condenser (E102): one path is connected to the top of the bulkhead rectification tower through a tower top return pipe (10), and the other path is connected to a tower top output pipe (11); the side-line carbon tetrachloride extraction pipe (12) is connected to a carbon tetrachloride product tank (V101) after passing through a cooler (E103); an o-dichlorobenzene solvent extraction pipe (14) is arranged below the public stripping section (4), the o-dichlorobenzene solvent extraction pipe (14) is connected to an o-dichlorobenzene recovery tank (V102) after passing through a condenser (E104), and a partition wall rectifying tower reboiler (E101) is arranged below the o-dichlorobenzene solvent extraction pipe (14).

3. The apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent according to claim 2, characterized in that: two tower plates are arranged between the partition plate (2) and the public rectification section (3), the tower plates are sieve plates or floating valve tower plates, all liquid collected on the tower plates enters a distribution tank (V103), then enters a tank outlet pipeline A (17) and a tank outlet pipeline B (18) and respectively enters a liquid collecting redistributor A (19) and a liquid collecting redistributor B (20) at the left side and the right side of the partition plate, and then respectively enters an upper packing layer (5) at the left side of the partition plate and an upper packing layer (7) at the right side of the partition plate; and regulating valves are arranged on the tank outlet pipeline A (17) and the tank outlet pipeline B (18).

4. The apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent as claimed in claim 2, wherein a semicircular column plate A (21) and a semicircular column plate B (22) are respectively arranged below the lower packing layer (6) on the left side of the partition plate and the lower packing layer (8) on the right side of the partition plate, the semicircular column plates are sieve plates or valve trays, the aperture ratio is 5 ~ 10%, and a liquid collecting redistributor C (23) is arranged below the semicircular column plates A and B.

5. The apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent according to claim 2, characterized in that: the reboiler (E101) of the bulkhead rectifying tower is a vertical tubular heat exchanger, and the specification of the reboiler tube is phi 38 multiplied by 2.5mm or phi 38 multiplied by 3 mm.

6. The apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent as set forth in claim 2, wherein the number of plates of said common rectifying section (3) and said common stripping section (4) is 4 ~ 6, the number of plates of said upper packing layer (5) on the left side of said partition and said lower packing layer (6) on the left side of said partition is 8 ~ 12, the number of plates of said upper packing layer (7) on the right side of said partition is 4 ~ 6, and the number of plates of said lower packing layer (8) on the right side of said partition is 12 ~ 18.

7. A process using the apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent according to any one of claims 1 to 6, comprising the steps of: mixed liquid containing o-dichlorobenzene, carbon tetrachloride, phosgene, hydrogen chloride and a small amount of toluene diisocyanate enters a packing layer (5) at the upper part of the left side of a partition plate (2) in a partition wall rectifying tower (T101) and a packing layer (6) at the lower part of the left side of the partition plate from a feeding pipe (1) and then enters a public rectifying section (3) for rectification, and a part of materials flow into a partial condenser (E102) at the top of the tower through a steam pipe (9) at the top of the tower and then are divided into two paths: one path of the gas flows into the top of the bulkhead rectification tower again through a tower top return pipe (10), and the other path of the gas which is not condensed is led into a phosgene recovery system through a tower top output pipe (11) to obtain phosgene, hydrogen chloride and a small amount of carbon tetrachloride; the other part of the material flows into a packing layer (7) at the upper part of the right side of the clapboard and is divided into two paths, one path of the material passes through a lateral carbon tetrachloride extraction pipe (12), then passes through a cooler (E103), reaches a carbon tetrachloride product tank (V101), and then is led out through a carbon tetrachloride product pipe (13) to obtain carbon tetrachloride with the purity of more than 99.95 percent; the gas which is not cooled is directly discharged into a top extraction pipe (11) and is led into a phosgene recovery system; the other path flows into a public stripping section (4) through a packing layer (8) at the lower part of the right side of the partition plate and is divided into two paths, one path is sent into an o-dichlorobenzene recovery tank (V102) through an o-dichlorobenzene solvent extraction pipe (14) and a condenser (E104) and then is led out through an o-dichlorobenzene solvent pipe, so that o-dichlorobenzene with the purity of more than 99.9 percent is obtained; the other path of the liquid flows into a reboiler (E101) of the next-door rectifying tower to be reheated and vaporized, the vapor generated by vaporization returns to the upper part of the next-door rectifying tower (T101), and the unvaporized liquid flows downwards to flow through the bottom of the next-door rectifying tower (T101) and is discharged through a tower bottom residual liquid extraction pipe (16) to obtain a small amount of o-dichlorobenzene and toluene diisocyanate.

8. The process of the equipment for recovering and purifying the photochemical reaction solvent o-dichlorobenzene according to claim 7, wherein the operation pressure of the next door rectifying tower (T101) is 120kPa, the reflux ratio of the top of the tower is 5 ~ 8, and the heating medium of the reboiler (E101) of the next door rectifying tower is heat-conducting oil.

Technical Field

The invention belongs to the technical field of separation, particularly relates to equipment and a process for recovering and purifying ortho-dichlorobenzene serving as a photochemical reaction solvent, and particularly relates to equipment and a process for separating and recovering ortho-dichlorobenzene and carbon tetrachloride solvents by a partition rectifying tower with a side line extraction and a built-in reboiler.

Background

In the process of producing TDI by a liquid phase phosgene method, the reaction rate is often improved by increasing the using amount of phosgene, and a large amount of an organic solvent, namely o-dichlorobenzene (ODCB), is added to reduce the occurrence of side reactions. In the process of synthesizing phosgene, a small amount of carbon tetrachloride is generated due to the purity of raw materials, but the carbon tetrachloride can be continuously accumulated in a reaction system to reach higher concentration along with the production, and because the boiling point of the carbon tetrachloride is lower than that of o-dichlorobenzene and toluene diisocyanate, the carbon tetrachloride mainly exists in gas-phase phosgene, so that the effective partial pressure of the phosgene is reduced, and the phenomena of large phosgene circulation amount and high excess phosgene of the system are caused. Also, the presence of small amounts of carbon tetrachloride during photochemical reactions can exacerbate the formation of by-products.

Therefore, the invention utilizes the next door rectifying tower to remove the solvent o-dichlorobenzene, carbon tetrachloride, phosgene, hydrogen chloride and a small amount of toluene diisocyanate in the photochemical reaction process, so as to obtain the high-purity solvent o-dichlorobenzene for the photochemical reaction, avoid the adverse effect of impurities in the solvent on the photochemical reaction, recover the phosgene, collect the high-purity carbon tetrachloride byproduct from the side line, divide the middle part of the rectifying tower into a left part and a right part through a partition plate, ensure the purity of the carbon tetrachloride collected from the side line on one hand, and avoid the influence of raw material composition on the purity of the carbon tetrachloride and the purity of the o-dichlorobenzene recovered from the bottom of the tower when the impurity composition in the solvent o-dichlorobenzene is different on the other hand; meanwhile, the reboiler is internally arranged, so that the retention time of materials in the reboiler and the tower kettle is obviously reduced, and the generation of byproducts caused by high-temperature heating is reduced to the maximum extent.

Disclosure of Invention

In view of the defects of the prior art, the technical problem to be solved by the invention is to provide equipment and a process for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a device for recovering and purifying photochemical reaction solvent o-dichlorobenzene comprises a bulkhead rectifying tower, a partial condenser at the top of the tower, a cooler, a carbon tetrachloride product tank, a condenser and an o-dichlorobenzene recovering tank which are connected with each other through pipelines.

Preferably, the middle part of next door rectifying column is provided with the baffle, and the upper portion of baffle is public rectification section, and the lower part of baffle is public stripping section, the left side of baffle is divided into baffle left side upper portion packing layer and baffle left side lower part packing layer by the inlet pipe, the right side of baffle is divided into baffle right side upper portion packing layer and baffle right side lower part packing layer by side line carbon tetrachloride extraction pipe, next door rectifying column top divides into two tunnel after being connected to the top of the tower partial condenser through the top of the tower steam pipe: one path is connected to the top of the bulkhead rectification tower through a tower top return pipe, and the other path is connected to a tower top output pipe; the side-line carbon tetrachloride extraction pipe is connected to a carbon tetrachloride product tank after passing through the cooler; an ortho-dichlorobenzene solvent extraction pipe is arranged below the public stripping section, the ortho-dichlorobenzene solvent extraction pipe is connected to an ortho-dichlorobenzene recovery tank through a condenser, and a partition wall rectifying tower reboiler is arranged below the ortho-dichlorobenzene solvent extraction pipe.

Preferably, two tower plates are arranged between the partition plate and the public rectification section, the tower plates are sieve plates or floating valve tower plates, all liquid collected on the tower plates enters the distribution tank, and then enters the tank outlet pipeline A and the tank outlet pipeline B to respectively enter the liquid collecting redistributor A and the liquid collecting redistributor B on the left side and the right side of the partition plate and then respectively enter the packing layer on the upper part of the left side of the partition plate and the packing layer on the upper part of the right side of the partition plate; and regulating valves are arranged on the tank outlet pipeline A and the tank outlet pipeline B.

Preferably, a semicircular column plate A and a semicircular column plate B are arranged below the packing layer at the lower part of the left side of the partition plate and the packing layer at the lower part of the right side of the partition plate, the semicircular column plates are sieve plates or floating valve column plates, the opening rate is 5 ~ 10%, and a liquid collecting redistributor C is arranged below the semicircular column plates A and B.

Preferably, the dividing wall rectifying tower reboiler is a vertical tubular heat exchanger, and the reboiler has the specification of phi 38 multiplied by 2.5mm or phi 38 multiplied by 3 mm.

Preferably, the number of plates of the common rectifying section and the common stripping section is 4 ~ 6, the number of plates of the upper packing layer on the left side of the partition and the lower packing layer on the left side of the partition is 8 ~ 12, the number of plates of the upper packing layer on the right side of the partition is 4 ~ 6, and the number of plates of the lower packing layer on the right side of the partition is 12 ~ 18.

A process for recovering and purifying equipment of photochemical reaction solvent o-dichlorobenzene comprises the following steps: mixed liquid containing o-dichlorobenzene, carbon tetrachloride, phosgene, hydrogen chloride and a small amount of toluene diisocyanate enters a packing layer at the upper part of the left side of a partition plate (2) in a partition wall rectifying tower from a feeding pipe and a packing layer at the lower part of the left side of the partition plate, then enters a public rectifying section for rectification, and a part of materials flow into a partial condenser at the top of the tower through a steam pipe at the top of the tower and then are divided into two paths: one path of the gas flows into the top of the next-door rectifying tower again through a tower top return pipe, and the other path of the gas which is not condensed is led into a phosgene recovery system through a tower top output pipe to obtain phosgene, hydrogen chloride and a small amount of carbon tetrachloride; the other part of the material flows into a packing layer at the upper part of the right side of the clapboard and is divided into two paths, one path of the material passes through a lateral carbon tetrachloride extraction pipe, then passes through a cooler and then reaches a carbon tetrachloride product tank, and then is led out through a carbon tetrachloride product pipe to obtain carbon tetrachloride with the purity of more than 99.95 percent; directly discharging uncooled gas into a tower top extraction pipe, and introducing the uncooled gas into a phosgene recovery system; the other path flows into a public stripping section through a packing layer at the lower part of the right side of the partition plate and is divided into two paths, one path is sent into an o-dichlorobenzene recovery tank through an o-dichlorobenzene solvent extraction pipe and a condenser, and then is led out through an o-dichlorobenzene solvent pipe to obtain o-dichlorobenzene with the purity of more than 99.9 percent; the other path of the liquid flows into a reboiler of the next-door rectifying tower to be reheated and vaporized, the vapor generated by vaporization returns to the upper part of the next-door rectifying tower, and the unvaporized liquid flows downwards to the bottom of the next-door rectifying tower and is discharged through a tower bottom residual liquid extraction pipe to obtain a small amount of o-dichlorobenzene and toluene diisocyanate.

Preferably, the operation pressure of the bulkhead rectifying tower is 120kPa, the reflux ratio of the tower top is 5 ~ 8, and the heating medium of the reboiler of the bulkhead rectifying tower is heat-conducting oil.

The invention has the advantages that:

(1) through next door rectifying column middle part setting baffle, at baffle left side middle part feeding, baffle right side upper portion siding extraction, can guarantee the carbon tetrachloride accessory substance of siding extraction mass fraction more than 99.95%, avoided simultaneously in the solvent o-dichlorobenzene raw materials impurity composition not simultaneous, raw materials composition, raw materials feeding volume, raw materials temperature etc. factor are to carbon tetrachloride purity and the influence of retrieving o-dichlorobenzene purity at the bottom of the tower.

(2) The upper part and the lower part of the partition plate of the partition tower are provided with a plurality of tower plates, so that the liquid and gas distribution on two sides of the partition plate of the partition tower is realized.

(3) The ortho-dichlorobenzene solvent is collected from the side line of the tower kettle, the content of toluene diisocyanate in the ortho-dichlorobenzene solvent is reduced, the purity of the solvent is improved, and the adverse effect on the photochemical reaction is ensured when the ortho-dichlorobenzene solvent is recycled.

(4) The tower kettle reboiler is arranged in the rectifying tower body, so that the retention time of materials in the tower, particularly in the reboiler, is obviously shortened, and byproducts generated by high-temperature heating are avoided to the maximum extent.

Drawings

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention;

FIG. 2 is an enlarged view of FIG. 1 at A;

FIG. 3 is an enlarged view of FIG. 1 at B;

in the figure: t101-next door rectifying tower, E101-built-in reboiler, E102-tower top dephlegmator, E103-carbon tetrachloride cooler, E104-o-dichlorobenzene condenser, V101-carbon tetrachloride product tank, V102-o-dichlorobenzene recovery tank, V103-liquid distribution tank, 1-feeding pipe, 2-partition plate, 3-common rectifying section, 4-common stripping section, 5-partition plate left side upper packing layer, 6-partition plate left side lower packing layer, 7-partition plate right side upper packing layer, 8-partition plate right side lower packing layer, 9-tower top steam pipe, 10-tower top return pipe, 11-tower top extraction pipe, 12-side line carbon tetrachloride extraction pipe, 13-carbon tetrachloride product pipe, 14-solvent extraction pipe, 15-o-dichlorobenzene solvent pipe, 16-a residual liquid extraction pipe at the bottom of the tower, 17-a tank outlet pipeline A, 18-a tank outlet pipeline B, 19-a liquid collection redistributor A, 20-a liquid collection redistributor B, 21-a semicircular tower plate A, 22-a semicircular tower plate B, 23-a liquid collection redistributor C.

Detailed Description

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

As shown in FIG. 1 ~ 3, an apparatus for recovering and purifying ortho-dichlorobenzene as a photochemical reaction solvent comprises a dividing wall rectifying tower (T101), a partial condenser (E102) at the top of the tower, a cooler (E103), a carbon tetrachloride product tank (V101), a condenser (E104) and an ortho-dichlorobenzene recovering tank (V102) which are connected with each other through pipelines.

In the embodiment of the invention, a partition plate (2) is arranged in the middle of a bulkhead rectifying tower, the upper part of the partition plate (2) is a public rectifying section (3), the lower part of the partition plate (2) is a public stripping section (4), the left side of the partition plate (2) is divided into a partition plate left upper packing layer (5) and a partition plate left lower packing layer (6) by a feeding pipe (1), the right side of the partition plate (2) is divided into a partition plate right upper packing layer (7) and a partition plate right lower packing layer (8) by a side-line carbon tetrachloride extraction pipe (12), and the top of the bulkhead rectifying tower is divided into two parts after being connected to a tower top partial condenser (E102) through a tower top steam pipe: one path is connected to the top of the bulkhead rectification tower through a tower top return pipe (10), and the other path is connected to a tower top output pipe (11); the side-line carbon tetrachloride extraction pipe (12) is connected to a carbon tetrachloride product tank (V101) after passing through a cooler (E103); an o-dichlorobenzene solvent extraction pipe (14) is arranged below the public stripping section (4), the o-dichlorobenzene solvent extraction pipe (14) is connected to an o-dichlorobenzene recovery tank (V102) after passing through a condenser (E104), and a partition wall rectifying tower reboiler (E101) is arranged below the o-dichlorobenzene solvent extraction pipe (14).

In the embodiment of the invention, two tower plates are arranged between the partition plate (2) and the public rectification section (3), the tower plates are sieve plates or floating valve tower plates, all liquid collected on the tower plates enters a distribution tank (V103), and then enters a tank outlet pipeline A (17) and a tank outlet pipeline B (18) to respectively enter a liquid collecting redistributor A (19) and a liquid collecting redistributor B (20) at the left side and the right side of the partition plate and then respectively enter an upper packing layer (5) at the left side of the partition plate and an upper packing layer (7) at the right side of the partition plate; and regulating valves are arranged on the tank outlet pipeline A (17) and the tank outlet pipeline B (18).

In the embodiment of the invention, a semicircular column plate A (21) and a semicircular column plate B (22) are respectively arranged below the lower packing layer (6) on the left side of the partition plate and the lower packing layer (8) on the right side of the partition plate, the semicircular column plate is in a sieve plate or float valve column plate form, the opening rate is 5 ~ 10%, and a liquid collecting redistributor C (23) is arranged below the semicircular column plates A and B.

In the embodiment of the invention, the dividing wall rectifying tower reboiler (E101) is a vertical tubular heat exchanger, and the specification of the reboiler tube is phi 38 multiplied by 2.5mm or phi 38 multiplied by 3 mm.

In the embodiment of the invention, the number of plates of the common rectifying section (3) and the common stripping section (4) is 4 ~ 6, the number of plates of the upper packing layer (5) on the left side of the partition plate and the lower packing layer (6) on the left side of the partition plate is 8 ~ 12, the number of plates of the upper packing layer (7) on the right side of the partition plate is 4 ~ 6, and the number of plates of the lower packing layer (8) on the right side of the partition plate is 12 ~ 18.

A process for recovering and purifying equipment of photochemical reaction solvent o-dichlorobenzene comprises the following steps: mixed liquor containing o-dichlorobenzene, carbon tetrachloride, phosgene, hydrogen chloride and a small amount of toluene diisocyanate enters a partition plate left upper packing layer (5) and a partition plate left lower packing layer (6) of a partition plate (2) in a partition wall rectifying tower (T101) from a feeding pipe (1), passes through a tower plate between a public rectifying section (3) and the partition plate (2), then enters the public rectifying section (3) for rectification, and a part of materials flow into a partial condenser (E102) at the top of the tower through a steam pipe (9) at the top of the tower and then are divided into two paths: one path of the gas flows into the top of the bulkhead rectification tower again through a tower top return pipe (10), and the other path of the gas which is not condensed is led into a phosgene recovery system through a tower top output pipe (11) to obtain phosgene, hydrogen chloride and a small amount of carbon tetrachloride; the other part of the material flows into a liquid distribution tank (V103), then a liquid collection redistributor B (20) is discharged from a tank outlet pipeline B (18), then the other part of the material flows into a packing layer (7) at the upper part of the right side of the clapboard, and is divided into two paths, wherein one path of the material passes through a lateral line carbon tetrachloride extraction pipe (12), then passes through a cooler (E103), reaches a carbon tetrachloride product tank (V101), and then is led out through a carbon tetrachloride product pipe (13), so that carbon tetrachloride with the purity of more than 99.95 percent is obtained; the gas which is not cooled is directly discharged into a top extraction pipe (11) and is led into a phosgene recovery system; the other path of the liquid flows into a semicircular tower plate B (22) through a packing layer (8) at the lower part of the right side of the partition plate, then flows into a liquid collecting redistributor C (23), is discharged into a public stripping section (4) and is divided into two paths, one path of the liquid passes through an o-dichlorobenzene solvent extraction pipe (14) and a condenser (E104), then is sent into an o-dichlorobenzene recovery tank (V102), and then is led out through an o-dichlorobenzene solvent pipe to obtain o-dichlorobenzene with the purity of more than 99.9 percent; the other path of the liquid flows into a reboiler (E101) of the next-door rectifying tower to be reheated and vaporized, the vapor generated by vaporization returns to the upper part of the next-door rectifying tower (T101), and the unvaporized liquid flows downwards to flow through the bottom of the next-door rectifying tower (T101) and is discharged through a tower bottom residual liquid extraction pipe (16) to obtain a small amount of o-dichlorobenzene and toluene diisocyanate.

In the embodiment of the invention, the operation pressure of the bulkhead rectifying tower (T101) is 120kPa, the reflux ratio of the top of the bulkhead rectifying tower is 5 ~ 8, and the heating medium of the bulkhead rectifying tower reboiler (E101) is heat-conducting oil.