Chloroacetic acid tail gas treatment device

Abstract

The utility model provides a kind of chloroacetic acid tail gas treatment device, including filler column, condenser, acetic acid washing tank and cyclone separator;The filler column includes the first filler column and the second filler column connected in parallel, for absorbing acetic acid and acetyl chloride steam in tail gas, realize the preliminary purification of tail gas and the recovery of acetic acid resource;The condenser includes primary condenser and secondary condenser, for the staged condensation treatment of preliminary purified tail gas, obtain condensate and condensed gas;The acetic acid washing tank is used to store and recycle acetic acid washing liquid;The cyclone separator is used to separate liquid drop entrained in condensed gas, prevent entering subsequent acetic acid and hydrochloric acid system.The utility model is by using double-tower parallel packing absorption, two-stage depth refrigeration condensation and cyclone separation demisting etc. Structure design, significantly improve the recovery rate of acetic acid and acetyl chloride, effectively reduce tail gas emission concentration.

Description

Technical Field

[0001] This utility model relates to the field of exhaust gas treatment technology, specifically to a chloroacetic acid exhaust gas treatment device. Background Technology

[0002] Currently, the chloroacetic acid production process uses sulfur or acetic anhydride as catalysts. The production exhaust gas produces hydrogen chloride gas, which carries volatile low-boiling substances such as acetic acid, acetic anhydride, and acetyl chloride. Common exhaust gas treatment methods include water washing for acetic acid and hydrochloric acid recovery systems. However, water absorption leads to hydrolysis of catalysts such as acetic anhydride and acetyl chloride, resulting in catalyst waste and low utilization of recovered acetic acid, leading to raw material waste. Another method involves series packed tower absorption, using water or dilute acetic acid as the absorbent, with gas-liquid contact within the packed tower. The lack of a backup tower design prevents adjustments based on exhaust gas load, affecting continuous production. Finally, some processes directly discharge the condensed exhaust gas without deep purification units, resulting in liquid droplets in the exhaust gas, causing material loss and potentially corroding downstream pipelines or polluting the environment.

[0003] Therefore, there is an urgent need to develop a highly efficient absorption and deep purification device for chloroacetic acid tail gas treatment, so as to achieve high acetic acid recovery, ultra-low emissions of tail gas, and continuous and stable operation of the system. Utility Model Content

[0004] The main objective of this invention is to provide a chloroacetic acid tail gas treatment device to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A chloroacetic acid tail gas treatment device includes a packed tower, a condenser, an acetic acid scrubbing tank, and a cyclone separator. The packed tower includes a first packed tower and a second packed tower connected in parallel, used to absorb acetic acid and acetyl chloride vapors in the tail gas, achieving preliminary purification of the tail gas and recovery of acetic acid and acetyl chloride resources. The condenser includes a primary condenser and a secondary condenser, used to perform staged condensation treatment on the preliminarily purified tail gas to obtain condensate and condensed gas. The acetic acid scrubbing tank is used to store and circulate the acetic acid scrubbing liquid. The cyclone separator is used to separate liquid droplets entrained in the condensed gas to prevent them from entering the subsequent acetic acid and hydrochloric acid systems. The bottom and top of the first packed tower are respectively equipped with... The system has a first liquid phase outlet pipe and a first gas phase outlet pipe. The bottom of the second packed tower is provided with a second liquid phase outlet pipe, which is connected in parallel with the first liquid phase outlet pipe to form a first combined liquid phase pipe, used to transport the acetic acid discharged from the bottom of the first and second packed towers to the acetic acid washing tank. The top of the second packed tower is provided with a second gas phase outlet pipe, which is connected in parallel with the first gas phase outlet pipe to form a combined gas phase pipe, used to transport the tail gas after preliminary purification by the packed tower to the first-stage condenser. The uncondensed gas in the first-stage condenser enters the second-stage condenser through a third gas phase outlet pipe. The uncondensed gas in the second-stage condenser enters the cyclone separator through a fourth gas phase outlet pipe.

[0006] Preferably, the first packed tower is provided with a first PP packing and a first liquid distributor. The first PP packing is located at the top of the first packed tower to increase the gas-liquid contact interface and promote the dissolution and absorption of acetic acid and acetyl chloride vapor in the exhaust gas. The first liquid distributor is located above the first PP packing with Pall rings to uniformly spray the washing liquid from the acetic acid washing tank onto the first PP packing, ensuring efficient gas-liquid contact and acetic acid recovery.

[0007] Preferably, the second packed tower is equipped with a second PP packing of Pall rings and a second liquid distributor. The second PP packing is located at the top of the second packed tower to increase the gas-liquid contact interface and promote the dissolution and absorption of acetic acid and acetyl chloride vapor in the exhaust gas. The second liquid distributor is located above the second PP packing of Pall rings to uniformly spray the washing liquid from the acetic acid washing tank onto the second PP packing, ensuring efficient gas-liquid contact and acetic acid recovery.

[0008] Preferably, the lower left side of the first packed tower is connected to the first tail gas inlet pipe, which is used to receive tail gas containing acetic acid and acetyl chloride discharged from the chloroacetic acid unit.

[0009] Preferably, the lower left side of the second packed tower is connected to the second tail gas inlet pipe, which is used to receive tail gas from the chloroacetic acid unit.

[0010] Preferably, the bottom of the acetic acid washing tank is connected to the inlet of the washing tank condenser via a circulation outlet pipe, and the top is connected to the outlet of the washing tank condenser via a return pipe. The washing tank condenser is used to reduce the temperature of the circulating washing liquid and improve the recovery efficiency of acetic acid and acetyl chloride.

[0011] Preferably, a thermometer is installed on the return pipe to monitor the temperature of the washing liquid after cooling in real time.

[0012] Preferably, the circulation outlet pipe is equipped with a circulation pump for circulating the acetic acid washing liquid back to the acetic acid washing tank after it has been cooled by a cooler.

[0013] Preferably, the bottom of the acetic acid washing tank is connected to the first liquid distributor of the first packed tower and the second liquid distributor of the second packed tower via spray pipes; a spray pump is installed on the spray pipes to draw the washing liquid from the bottom of the acetic acid washing tank and deliver it to the distributor in the packed tower.

[0014] Preferably, the acetic acid washing tank is equipped with a level gauge on top, which is linked to the spray pump and automatically starts the liquid replenishment program when the liquid level is lower than the set value.

[0015] Preferably, the upper left side of the primary condenser is connected to the combined gas phase pipeline for condensing the pre-purified exhaust gas. The condensed acetic acid liquid enters the condensate receiving tank through the bottom third liquid phase outlet pipeline.

[0016] Preferably, the lower left side of the secondary condenser is connected to the third gas phase outlet pipe for further condensing the acetic acid and acetyl chloride vapors that have not been cooled by the primary condenser; the condensed acetic acid and acetyl chloride vapors enter the condensate receiving tank through the bottom fourth liquid phase outlet pipe.

[0017] Preferably, the third liquid phase outlet pipe and the fourth liquid phase outlet pipe are connected in parallel to form a second merged liquid phase pipe, which collects the acetic acid cooled by the first-stage condenser and the second-stage condenser and then transports it to the condensate receiving tank.

[0018] Preferably, the lower part of the cyclone separator is connected to the fourth gas phase outlet pipe to separate liquid droplets entrained in the gas after condensation by the secondary condenser, preventing them from entering the subsequent acetic acid and hydrochloric acid systems; the separated clean gas is discharged from the top of the cyclone separator and enters the acetic acid system for further processing.

[0019] The beneficial effects of this utility model are as follows: The chloroacetic acid tail gas treatment device of this invention adopts a parallel structure packed tower design, which can be flexibly switched to ensure continuous operation of the treatment device; the combination of multi-stage condenser and cyclone separator can efficiently recover acetic acid and acetyl chloride, reduce emission concentration, realize the resource utilization of acetic acid and acetyl chloride, and at the same time realize closed-loop circulation of washing liquid, system switching without shutdown and precise temperature control. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the chloroacetic acid tail gas treatment device of this utility model; In the diagram: First packed tower 1, first PP packing 101, first liquid distributor 102, first tail gas inlet pipe 103, second tail gas inlet pipe 104; Second packed tower 2, second PP packing 201, second liquid distributor 202, washing tank condenser 3; Acetic acid washing tank 4, first combined liquid phase pipe 401, reflux pipe 402, circulation outlet pipe 403, spray pipe 404, thermometer 405, level gauge 406; Circulation pump 5; Spray pump 6; First-stage condenser 7, combined gas phase pipe 701; Second-stage condenser 8; Transfer pump 9; Condensate receiving tank 10, second combined liquid phase pipe 1001, transfer pipe 1002; Cyclone separator 11. Detailed Implementation

[0021] A chloroacetic acid tail gas treatment device includes a packed tower, a condenser, an acetic acid scrubbing tank 4, and a cyclone separator 11. The packed tower includes a first packed tower 1 and a second packed tower 2 connected in parallel, used to absorb acetic acid vapor in the tail gas, achieving preliminary purification of the tail gas and recovery of acetic acid and acetyl chloride resources. The condenser includes a primary condenser 7 and a secondary condenser 8, used to perform staged condensation treatment on the preliminarily purified tail gas to obtain condensate and condensed gas. The acetic acid scrubbing tank 4 is used to store and circulate acetic acid scrubbing liquid. The cyclone separator 11 is used to separate liquid droplets entrained in the condensed gas to prevent them from entering the subsequent acetic acid and hydrochloric acid system. The bottom and top of the first packed tower 1 are respectively provided with a first liquid... The second packed tower 2 has a first gas phase outlet pipe and a second liquid phase outlet pipe at its bottom, which is connected in parallel with the first liquid phase outlet pipe to form a first combined liquid phase pipe 401, used to transport the acetic acid discharged from the bottom of the first packed tower 1 and the second packed tower 2 to the acetic acid washing tank 4; the second packed tower 2 has a second gas phase outlet pipe at its top, which is connected in parallel with the first gas phase outlet pipe to form a combined gas phase pipe 701, used to transport the tail gas after preliminary purification by the packed tower to the first-stage condenser 7; the uncondensed gas from the first-stage condenser 7 enters the second-stage condenser 8 through the third gas phase outlet pipe; the uncondensed gas from the second-stage condenser 8 enters the cyclone separator 11 through the fourth gas phase outlet pipe.

[0022] In a preferred embodiment, the first packed tower 1 is provided with a Pall ring first PP packing 101 and a first liquid distributor 102. The first PP packing 101 is located at the upper part of the first packed tower 1 to increase the gas-liquid contact interface and promote the dissolution and absorption of acetic acid and acetyl chloride vapor in the exhaust gas. The first liquid distributor 102 is located above the Pall ring first PP packing 101 to uniformly spray the washing liquid from the acetic acid washing tank 4 onto the first PP packing 101 to ensure efficient gas-liquid contact and acetic acid recovery.

[0023] In a preferred embodiment, the second packed tower 2 is provided with a second PP packing 201 of Pall rings and a second liquid distributor 202. The second PP packing 201 is located at the upper part of the second packed tower 2 to increase the gas-liquid contact interface and promote the dissolution and absorption of acetic acid and acetyl chloride vapor in the exhaust gas. The second liquid distributor 202 is located above the second PP packing 201 of Pall rings to uniformly spray the washing liquid from the acetic acid washing tank 4 onto the second PP packing 201 to ensure efficient gas-liquid contact and acetic acid recovery.

[0024] This utility model adopts a first packed tower 1 and a second packed tower 2 arranged in parallel. It can select single tower operation, dual tower operation at the same time, or one-tower standby mode according to different exhaust gas loads. When one of the packed towers needs cleaning or maintenance, it can be switched to the other packed tower to ensure continuous and stable operation of the system.

[0025] As a preferred embodiment, the lower left side of the first packed tower 1 is connected to the first tail gas inlet pipe 103, which is used to receive tail gas containing acetic acid and acetyl chloride discharged from the chloroacetic acid unit.

[0026] In a preferred embodiment, the lower left side of the second packed tower 2 is connected to the second tail gas inlet pipe 104, which is used to receive tail gas from the chloroacetic acid unit.

[0027] As a preferred embodiment, the upper left side of the primary condenser 7 is connected to the combined gas phase pipeline 701 for condensing the pre-purified exhaust gas. The condensed acetic acid liquid enters the condensate receiving tank 10 through the bottom third liquid phase outlet pipeline.

[0028] As a preferred embodiment, the lower left side of the secondary condenser 8 is connected to the third gas phase outlet pipe for further condensing the acetic acid and acetyl chloride vapors that have not been cooled by the primary condenser 7; the condensed acetic acid and acetyl chloride vapors enter the condensate receiving tank 10 through the bottom fourth liquid phase outlet pipe.

[0029] In a preferred embodiment, the third liquid phase outlet pipe and the fourth liquid phase outlet pipe are connected in parallel to form a second combined liquid phase pipe 1001, which collects the acetic acid cooled by the first-stage condenser 7 and the second-stage condenser 8 and transports it to the condensate receiving tank 10.

[0030] In a preferred embodiment, the lower part of the cyclone separator 11 is connected to the fourth gas phase outlet pipe to separate liquid droplets entrained in the gas after condensation by the secondary condenser 8, preventing them from entering the subsequent acetic acid and hydrochloric acid systems; the separated clean gas is discharged from the top of the cyclone separator 11 and enters the acetic acid system for further processing.

[0031] As a preferred embodiment, chilled brine with a temperature of -5 to -15°C is introduced into the primary condenser 7 to effectively condense most of the acetic acid vapor; chilled brine with a temperature of -15 to -30°C is introduced into the primary condenser 7 to further capture trace amounts of acetic acid and improve the acetic acid recovery rate.

[0032] In a preferred embodiment, the bottom of the acetic acid washing tank 4 is connected to the inlet of the washing tank condenser 3 via a circulation outlet pipe 403. The washing tank condenser 3 is used to reduce the temperature of the circulating washing liquid. The cooled washing liquid returns from the outlet of the washing tank condenser 3 to the top of the acetic acid washing tank 4 via a return pipe 402, forming an external circulation cooling loop to maintain the temperature of the washing liquid within a suitable range and improve the absorption capacity of acetic acid and acetyl chloride vapor.

[0033] As a preferred embodiment, a thermometer 405 is installed on the return pipe 402 to monitor the temperature of the washing liquid after cooling in real time.

[0034] As a preferred embodiment, the circulating outlet pipe 403 is equipped with a circulating pump 5, which is used to circulate the acetic acid washing liquid back to the acetic acid washing tank 4 after passing through the cooler 3, so as to maintain a stable temperature.

[0035] In a preferred embodiment, the bottom of the acetic acid washing tank 4 is connected to the liquid distributor 102 of the first packed tower 1 and the liquid distributor 202 of the second packed tower 2 via a spray pipe 404; a spray pump 6 is installed on the spray pipe 404 to draw the washing liquid from the bottom of the acetic acid washing tank 4 and deliver it to the distributor in the packed tower to achieve uniform spraying.

[0036] As a preferred embodiment, the top of the acetic acid washing tank 4 is equipped with a level gauge 406, and the spray pump 6 is linked with the level gauge 406. When the liquid level is lower than the set value, the liquid replenishment program is automatically started to ensure stable operation of the system.

[0037] In a preferred embodiment, the condensate receiving tank 10 is connected to the top of the acetic acid washing tank 4 via a conveying pipe 1002. A conveying pump 9 is installed on the conveying pipe 1002 to extract the condensate from the condensate receiving tank 10 and transport it back to the acetic acid washing tank 4 as supplementary washing liquid, thereby realizing closed-loop resource recycling.

[0038] The working principle of this utility model is as follows: In operation, the first tail gas containing acetic acid (chloroacetic acid) enters the first packed tower 1 and the second packed tower 2 via pipe 103 and pipe 104, respectively. Inside the first packed tower 1 and the second packed tower 2, the tail gas flows upwards and comes into countercurrent contact with the acetic acid solution sprayed onto the PP packing by liquid distributors 102 and 202. Acetic acid and acetyl chloride vapor in the tail gas are absorbed, forming a rich acetic acid solution. This solution is then combined through the first liquid phase outlet pipe and the second liquid phase outlet pipe at the bottom of the packed towers, and enters the acetic acid scrubbing tank 4 through the first combined liquid phase pipe 401. The gas purified by the first packed tower 1 and the second packed tower 2 is discharged from the top of the towers, combined through the first gas phase outlet pipe and the second gas phase outlet pipe, and enters the first-stage condenser 7 through the first combined gas phase pipe 701. In condenser 7, the gas is cooled by brine at a temperature of -5 to -15°C. Most of the acetic acid and acetyl chloride vapors are condensed into liquid and flow into condensate receiving tank 10 via the third liquid phase outlet pipe and merged into the combined liquid phase pipe 1001. The uncondensed gas continues to enter the secondary condenser 8. In the secondary condenser 7, the gas is further condensed and cooled by brine at a temperature of -15 to -30°C. The remaining acetic acid and acetyl chloride vapors continue to condense. The condensate flows into the combined liquid phase pipe 1001 via the fourth liquid phase outlet pipe and finally flows into condensate receiving tank 10. The remaining uncondensed gas enters cyclone separator 11 from the top of the secondary condenser 8. In cyclone separator 11, the entrained acetic acid droplets enter condensate receiving tank 10 via the bottom pipe. The clean gas is discharged from the top and sent to the acetic acid system.

[0039] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A chloroacetic acid tail gas treatment device, characterized in that: The system includes a packed tower, a condenser, an acetic acid scrubbing tank (4), and a cyclone separator (11). The packed tower includes a first packed tower (1) and a second packed tower (2) connected in parallel, used to absorb acetic acid and acetyl chloride vapors in the tail gas, achieving preliminary purification of the tail gas and recovery of acetic acid and acetyl chloride resources. The condenser includes a first-stage condenser (7) and a second-stage condenser (8), used to perform staged condensation treatment on the preliminarily purified tail gas to obtain condensate and condensate gas. The acetic acid scrubbing tank (4) is used to store and circulate acetic acid scrubbing liquid. The cyclone separator (11) is used to separate liquid droplets entrained in the condensate gas to prevent them from entering the subsequent acetic acid and hydrochloric acid system. The bottom and top of the first packed tower (1) are respectively provided with a first liquid phase outlet pipe and a second liquid phase outlet pipe. A gas phase outlet pipe is provided, and a second liquid phase outlet pipe is provided at the bottom of the second packed tower (2), which is connected in parallel with the first liquid phase outlet pipe to form a first combined liquid phase pipe (401), which is used to transport the acetic acid discharged from the bottom of the first packed tower (1) and the second packed tower (2) to the acetic acid washing tank (4); a second gas phase outlet pipe is provided at the top of the second packed tower (2), which is connected in parallel with the first gas phase outlet pipe to form a combined gas phase pipe (701), which is used to transport the tail gas after preliminary purification by the packed tower to the first-stage condenser (7); the uncondensed gas of the first-stage condenser (7) enters the second-stage condenser (8) through the third gas phase outlet pipe; the uncondensed gas of the second-stage condenser (8) enters the cyclone separator (11) through the fourth gas phase outlet pipe.

2. The chloroacetic acid tail gas treatment device according to claim 1, characterized in that: The first packed tower is provided with a first PP packing (101) and a first liquid distributor (102). The first PP packing (101) is located at the top of the first packed tower (1) to increase the gas-liquid contact interface and promote the dissolution and absorption of acetic acid and acetyl chloride vapor in the tail gas. The first liquid distributor (102) is located above the first PP packing (101) of the Pall ring and is used to uniformly spray the washing liquid from the acetic acid washing tank (4) onto the first PP packing (101).

3. The chloroacetic acid tail gas treatment device according to claim 1, characterized in that: The second packed tower (2) is provided with a second PP packing (201) and a second liquid distributor (202). The second PP packing (201) is located at the top of the second packed tower (2) to increase the gas-liquid contact interface and promote the dissolution and absorption of acetic acid and acetyl chloride vapor in the tail gas. The second liquid distributor (202) is located above the second PP packing (201) of the Pall ring and is used to uniformly spray the washing liquid from the acetic acid washing tank (4) onto the second PP packing (201).

4. The chloroacetic acid tail gas treatment device according to claim 1, characterized in that: The lower left side of the first packed tower (1) is connected to the first tail gas inlet pipe (103), which is used to receive tail gas containing acetic acid and acetyl chloride discharged from the chloroacetic acid unit.

5. The chloroacetic acid tail gas treatment device according to claim 1, characterized in that: The bottom of the acetic acid washing tank (4) is connected to the inlet of the washing tank condenser (3) through a circulation outlet pipe (403), and the top is connected to the outlet of the washing tank condenser (3) through a return pipe (402). The washing tank condenser (3) is used to reduce the temperature of the circulating washing liquid.

6. The chloroacetic acid tail gas treatment device according to claim 5, characterized in that: The acetic acid washing tank (4) is equipped with a level gauge (406) at the top, a thermometer (405) is installed on the return pipe (402), and a circulation pump (5) is installed on the circulation outlet pipe (403).

7. The chloroacetic acid tail gas treatment device according to claim 1, characterized in that: The bottom of the acetic acid washing tank (4) is connected to the first liquid distributor (102) of the first packed tower (1) and the second liquid distributor (202) of the second packed tower (2) through a spray pipe (404); a spray pump (6) is installed on the spray pipe (404).

8. The chloroacetic acid tail gas treatment device according to claim 1, characterized in that: The acetic acid washing tank (4) is equipped with a level gauge (406) on top. The level gauge (406) is linked with the spray pump (6). When the liquid level is lower than the set value, the liquid replenishment program is automatically started.

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