A green production process of chloroacetic acid

Abstract

The present application belongs to the field of chloroacetic acid production process, and particularly relates to a green production process of chloroacetic acid, which comprises S1 chlorination reaction, S2 gas stripping hydrolysis, S3 hydrolysis tail gas treatment, S4 primary high-temperature hydrogenation, S5 secondary low-temperature hydrogenation, S6 rectification and S7 distillation. The present application adds tail gas absorption before hydrogenation, removes hydrogen chloride from the source, and solves the problem of catalyst poisoning. The hydrogenation process is divided into two stages, the primary high-temperature hydrogenation is responsible for the rapid conversion of most of the dichloroacetic acid, and the secondary low-temperature hydrogenation completely reacts the residual dichloroacetic acid and stabilizes the generated monochloroacetic acid to avoid excessive reduction. The recovered acetic acid is recycled to the chlorination kettle through the recovery acetic acid tank, which reduces consumption and waste liquid, and only a small amount of high-boiling substance is discharged with a clear disposal path. The present application takes into account the yield, catalyst life and emission reduction, and has outstanding industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of chloroacetic acid production processes, and specifically relates to a green production process for chloroacetic acid. Background Technology

[0002] Currently, the mainstream industrial method for producing chloroacetic acid is the acetic acid catalytic chlorination process. This typically uses acetic acid and liquid chlorine as raw materials, undergoing a continuous chlorination reaction under the action of an acetic anhydride catalyst to produce a chlorinated liquid containing monochloroacetic acid, dichloroacetic acid, and unreacted acetic acid. To improve the yield of the target product, monochloroacetic acid, a catalytic hydrogenation process is usually employed, selectively reducing the byproduct dichloroacetic acid to monochloroacetic acid under the action of a palladium-on-carbon catalyst. This process route is mature and has been widely used in China.

[0003] However, existing catalytic hydrogenation processes have significant shortcomings in actual operation. First, the chlorinated liquid produced by the chlorination reaction inevitably carries a large amount of hydrogen chloride gas. This hydrogen chloride, after entering the hydrogenation reactor with the materials, severely poisons the palladium-carbon catalyst, leading to accelerated loss of its active component, palladium, and a significant shortening of the catalyst's lifespan. Second, to prevent monochloroacetic acid from being reduced to acetic acid due to over-hydrogenation, the hydrogenation reaction is currently controlled within a narrow suitable temperature window. However, due to the exothermic reaction and fluctuations in system composition, reactors operating at a single temperature range cannot simultaneously achieve efficient conversion of dichloroacetic acid and selective retention of monochloroacetic acid, creating a contradiction between the two.

[0004] To address the aforementioned problems, existing technologies either focus on using reactors made of special acid-resistant materials or improve catalyst resistance by optimizing catalyst formulations. However, neither approach systematically solves the problem of the continuous poisoning of catalysts by hydrogen chloride and the balance between reaction selectivity and conversion rate at the source of the process. Therefore, developing a chloroacetic acid production process that can effectively remove hydrogen chloride from hydrogenation feedstocks and employ a segmented temperature control strategy to optimize reaction selectivity has significant industrial application value. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a green production process for chloroacetic acid, which can effectively remove hydrogen chloride from the hydrogenation feedstock and adopts a segmented temperature control strategy to optimize the reaction and improve product conversion rate.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] The production process is a continuous chlorination method, including a reaction stage and a post-treatment stage. The reaction stage includes the following steps:

[0008] S1 Chlorination reaction: Acetic acid and acetic anhydride are introduced into the chlorination reactor, and liquid chlorine is added to carry out the chlorination reaction;

[0009] S2 stripping hydrolysis: The reactants after chlorination are fed into the acetyl chloride stripping tower, where they are separated into gas and liquid phases. The liquid phase from the acetyl chloride stripping tower flows by gravity into the hydrolysis reactor, where the acetyl chloride in the liquid phase after stripping is hydrolyzed into acetic acid and hydrochloric acid.

[0010] S3 Hydrolysis Tail Gas Treatment: In the hydrolysis reactor, the reaction produces a hydrolysis gas phase and a hydrolysis liquid phase. The hydrolysis gas phase enters the subsequent tail gas treatment process through an acetyl chloride stripping tower.

[0011] S4 First-stage high-temperature hydrogenation: The liquid phase output from the hydrolysis reactor enters the first hydrogenation reactor, and the reaction yields the first-stage hydrogenated liquid;

[0012] S5 Secondary Low-Temperature Hydrogenation: The primary hydrogenated liquid enters the second hydrogenation reactor, and the reaction yields the secondary hydrogenated liquid;

[0013] The secondary hydrogenated liquid described in S6 enters the post-processing stage to obtain chloroacetic acid product.

[0014] The post-processing stage includes the following steps:

[0015] S6 distillation: The secondary hydrogenated liquid enters the distillation column, the vapor phase at the top of the distillation column enters the second condenser, and the liquid phase at the bottom of the distillation column is crude chloroacetic acid product;

[0016] S7 Distillation: Crude chloroacetic acid enters the distillation tower. The vapor phase at the top of the distillation tower is chloroacetic acid vapor, which enters the solution preparation process. After being prepared into a 69% concentration chloroacetic acid solution, it is sent to the tank area for sale as a product. The bottom of the distillation tower contains high-boiling-point heavy component hazardous waste.

[0017] The acetic acid inlet of the chlorination reactor is connected to the acetic acid pipeline at the liquid phase outlet of the acetyl chloride absorption tower. The acetic acid inlet of the acetyl chloride absorption tower is connected to the outlet of the acetic acid storage tank via an acetic acid pipeline. The acetic anhydride inlet of the chlorination reactor is connected to the outlet of the acetic anhydride storage tank via an acetic anhydride pipeline. The heat exchange port of the chlorination reactor is connected to the heat exchanger port. The filtrate inlet of the chlorination reactor is connected to the liquid chlorine pipeline. The outlet of the chlorination reactor is connected to the inlet of the acetyl chloride stripping tower. The acetic acid recovery port of the chlorination reactor is connected to the second condenser via an acetic acid recovery pipeline.

[0018] In the subsequent exhaust gas treatment process, the exhaust gas sequentially passes through an acetyl chloride absorption tower, a first hydrogen chloride scrubbing tower, a falling film absorption tower with a first condenser, and a water-washing alkaline scrubbing tower. The gas phase outlet of the acetyl chloride absorption tower is connected to the inlet of the first hydrogen chloride scrubbing tower via an exhaust gas pipeline. The outlet of the first hydrogen chloride scrubbing tower is connected to the inlet of the falling film absorption tower via an exhaust gas pipeline. The outlet of the falling film absorption tower is connected to the inlet of the first condenser via an exhaust gas pipeline. The gas phase outlet of the first condenser is connected to the inlet of the water-washing alkaline scrubbing tower. The first condenser is also equipped with a liquid phase outlet.

[0019] The condensation temperature of the first condenser is 20-30℃. The first condensate output from the first condenser enters the neutralization tank for neutralization treatment. The first non-condensable product output from the first condenser contains hydrogen chloride and chlorine gas. The first non-condensable product is used as tail gas for subsequent tail gas treatment processes.

[0020] The outlet of the acetyl chloride stripping tower is connected to the inlet of the hydrolysis reactor via a stripping liquid phase pipeline. The outlet of the hydrolysis liquid phase of the hydrolysis reactor is connected to the inlet of the first hydrogenation reactor via a hydrolysis liquid phase pipeline. The outlet of the hydrolysis gas phase of the hydrolysis reactor is connected to the gas phase inlet of the acetyl chloride stripping tower. The outlet of the first hydrogenation reactor is connected to the inlet of the hydrogenated liquid of the second hydrogenation reactor via a hydrogenation pipeline. The first hydrogenation reactor and the second hydrogenation reactor are each provided with a hydrogen inlet and connected to a hydrogen pipeline. The first hydrogenation reactor and the second hydrogenation reactor are also each provided with a nitrogen inlet and connected to a nitrogen pipeline.

[0021] The outlet of the second hydrogenation reactor is connected to the inlet of the condensation stripping tower. The liquid phase outlet of the condensation stripping tower is connected to the distillation tower. The gas phase outlet of the condensation stripping tower is connected to the inlet of the second hydrogen chloride scrubbing tower. The gas phase outlet of the distillation tower is connected to the inlet of the second condenser. The liquid phase outlet of the distillation tower is connected to the inlet of the distillation tower. The distillation tower is provided with a gas phase outlet and a liquid phase outlet.

[0022] The condensation stripping tower is connected to the second hydrogenation reactor. The condensation stripping tower performs condensation stripping on the secondary hydrogenation liquid. The liquid phase of the condensed gas stripping tower enters the distillation tower, and the gas phase of the condensed gas stripping tower enters the second hydrogen chloride scrubbing tower for tail gas absorption. The second hydrogen chloride scrubbing tower is also connected to the falling film absorption tower. The remaining tail gas discharged from the second hydrogen chloride scrubbing tower enters the subsequent tail gas treatment process through the falling film absorption tower until it is vented.

[0023] In S1, the reaction temperature is 140-150℃, the pressure is 0.3-0.5MPa, the flow rate of acetic acid into the chlorination reactor is 1.1kmol / min, the flow rate of acetic anhydride into the chlorination reactor is 50mol / min, and the flow rate of liquid chlorine into the chlorination reactor is 1kmol / min.

[0024] In S4, the reaction temperature inside the first hydrogenation reactor is 140-150℃, the residence time is 60-90min, the pressure is 0.2-0.3MPa, and the hydrogen flow rate is 100-120L / min. A fixed bed carrying a palladium-carbon catalyst is set inside the first hydrogenation reactor.

[0025] In step S5, the reaction temperature inside the second hydrogenation reactor is 100-110℃, the residence time is 60-90min, the pressure is 0.2-0.3MPa, and the hydrogen flow rate is 80-90 L / min. A fixed bed carrying a palladium-carbon catalyst is provided inside the second hydrogenation reactor.

[0026] In S6, the bottom temperature of the distillation column is 130-140℃, the pressure is -0.10~-0.08MPa, the top gas phase is water and acetic acid, and the condensation temperature of the second condenser is 20-65℃.

[0027] In S7, the distillation column has a bottom temperature of 140-150℃ and a pressure of -0.10 to -0.08 MPa.

[0028] The beneficial effects of this invention are:

[0029] This invention incorporates tail gas absorption before hydrogenation, removing hydrogen chloride gas at the source and solving the problem of catalyst poisoning. This allows the palladium-carbon catalyst to maintain its activity for a longer period, and its lifespan is no longer limited by acidic gases in the feed. Regarding the hydrogenation process, this invention divides the hydrogenation into two stages: the first stage rapidly converts most of the dichloroacetic acid at high temperature, while the second stage, at a low temperature, completely reacts the remaining dichloroacetic acid while stabilizing the already formed monochloroacetic acid to prevent excessive reduction. Using two temperature stages to address the conversion and selectivity requirements respectively is far more effective than forcibly achieving equilibrium at a single temperature.

[0030] Furthermore, the acetic acid recovered through distillation is recycled back to the chlorination reactor via an acetic acid recovery tank, which not only reduces consumption but also waste liquid. The entire process ultimately requires only a small amount of high-boiling-point substances for external disposal, and the disposal path is clearly defined. Therefore, this invention achieves a balance between ensuring yield, extending catalyst life, and reducing emissions, demonstrating significant industrial application value. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the process of the present invention; Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0033] This invention discloses a green production process for chloroacetic acid. The process is a continuous chlorination method, and its principle is as follows: chlorine and acetic acid undergo a nucleophilic substitution reaction under the catalysis of acetyl chloride, mainly producing chloroacetic acid, with a small amount undergoing a side reaction to produce dichloroacetic acid. Under nitrogen displacement protection and palladium on carbon catalysis, dichloroacetic acid reacts with hydrogen to produce chloroacetic acid. The conversion rate of dichloroacetic acid to chloroacetic acid is 99%, and the remaining dichloroacetic acid content can be reduced to below 1.0%. The HCl gas generated in the reaction enters a falling film absorption tower, and is absorbed by dilute acid in a dilute acid storage tank to prepare a 31% hydrochloric acid solution.

[0034] Specific embodiments combined Figure 1 As shown, the green production process steps of chloroacetic acid of the present invention are as follows:

[0035] S1 Chlorination Reaction: Acetic acid flows from the acetic acid storage tank into the chlorination reactor at a rate of 1.1 kmol / min through the acetic acid pipeline, acetic anhydride flows from the acetic anhydride storage tank into the chlorination reactor at a rate of 50 mol / min through the acetic anhydride pipeline, and liquid chlorine flows into the chlorination reactor at a rate of 1 kmol / min through the liquid chlorine pipeline. The reaction temperature in the chlorination reactor is 140-150℃, and the pressure is 0.3-0.5 MPa, for the chlorination reaction to proceed.

[0036] In this process, acetic acid is first continuously pumped from the acetic acid storage tank into the acetyl chloride absorption tower, where it exchanges heat with the gas from the hydrolysis reactor and absorbs organic matter (acetyl chloride, etc.) and some HCl from the gas to obtain an acetic acid solution containing saturated HCl. This saturated HCl acetic acid solution is then introduced into the chlorination reactor, allowing the organic matter entrained in the gas to be recycled.

[0037] S2 stripping hydrolysis: The reactants after chlorination enter the acetyl chloride stripping tower, where gas and liquid phases are separated. The liquid phase from the acetyl chloride stripping tower flows by gravity into the hydrolysis reactor, where the acetyl chloride in the liquid phase after stripping is hydrolyzed into acetic acid and hydrochloric acid. The reaction temperature is 120-130℃ and the pressure is 0.3-0.6 MPa. The gas phase from the acetyl chloride stripping tower enters the acetyl chloride absorption tower for heat exchange with the acetic acid that also enters the absorption tower. At the same time, the acetic acid absorbs organic matter and some HCl in the gas phase. The gas phase after absorption is the tail gas, which enters the subsequent treatment process.

[0038] Acetyl chloride is converted into acetic acid and HCl, and the water involved in the reaction comes from the wash water of the first hydrogen chloride scrubbing tower.

[0039] S3 Hydrolysis Tail Gas Treatment: The tail gas after acetic acid absorption in the acetyl chloride absorption tower contains a small amount of acetic acid vapor. The tail gas enters the first hydrogen chloride scrubbing tower, where it is washed with 31% hydrochloric acid absorbent to absorb acetic acid vapor and other organic impurities (the wash water from the bottom of the first hydrogen chloride scrubbing tower enters the hydrolysis reactor to hydrolyze with acetyl chloride to obtain acetic acid and hydrochloric acid). The tail gas then enters the falling film absorption tower, where it absorbs HCl with dilute hydrochloric acid absorbent to prepare a 31% hydrochloric acid solution. The tail gas then enters the first condenser, where the condensate is neutralized in a neutralization tank and then sent to a wastewater treatment plant for treatment. The remaining gas is washed in a water-washing alkaline scrubbing tower (the alkaline scrubbing absorbent is a 15% sodium hydroxide aqueous solution). The remaining tail gas is then discharged through a 30m exhaust stack.

[0040] S4 First-stage high-temperature hydrogenation: The reaction temperature inside the first hydrogenation reactor is 140-150℃, the residence time is 60-90min, the pressure is 0.2-0.3MPa, and the hydrogen flow rate is 100-120L / min. A fixed bed carrying palladium-carbon catalyst is set inside the first hydrogenation reactor. The liquid phase output from the hydrolysis reactor enters the first hydrogenation reactor, and the reaction yields the first-stage hydrogenated liquid.

[0041] S5 Secondary Low-Temperature Hydrogenation: The reaction temperature inside the second hydrogenation reactor is 100-110℃, the residence time is 60-90min, the pressure is 0.2-0.3MPa, and the hydrogen flow rate is 80-90 L / min. A fixed bed carrying a palladium-carbon catalyst is set inside the second hydrogenation reactor. The primary hydrogenation liquid enters the second hydrogenation reactor, and the reaction yields the secondary hydrogenation liquid.

[0042] The product from the hydrolysis reactor, after heat exchange with steam, continuously enters a two-stage hydrogenation reactor, with hydrogen gas continuously introduced. Under the protection of nitrogen displacement and the catalytic action of palladium on carbon, dichloroacetic acid in the mixture is first reduced to chloroacetic acid by hydrogen at 140-150℃ and 0.2-0.3 MPa. At this point, the reaction liquid is the first-stage hydrogenation liquid. The first-stage hydrogenation liquid is then introduced into the second hydrogenation reactor, where the remaining dichloroacetic acid is reduced to chloroacetic acid at 100-110℃ and 0.2-0.3 MPa. At the same time, the low temperature can inhibit the reduction of chloroacetic acid to acetic acid, thereby increasing the yield. The conversion rate of dichloroacetic acid to chloroacetic acid is 99%, and the content of the remaining dichloroacetic acid can be reduced to below 1.0%.

[0043] Because the boiling points of chloroacetic acid and dichloroacetic acid, the products of the chlorination reaction, are close, high-purity products cannot be produced by simple distillation. A two-stage hydrogenation process is employed in the production flow to reduce most of the dichloroacetic acid to chloroacetic acid through hydrogenation, thereby reducing the excessive reduction of chloroacetic acid to acetic acid and improving the yield of chloroacetic acid.

[0044] The hydrogenated gas phase enters the condensation stripping tower from the bottom of the second hydrogenation reactor and is condensed. The condensate enters the distillation tower. The non-condensable gas mainly consists of hydrogen chloride, unreacted nitrogen, excess hydrogen, reaction byproducts such as acetaldehyde, and acetic acid vapor. The non-condensable gas enters the second hydrogen chloride scrubbing tower and is scrubbed with 31% hydrochloric acid to remove organic matter (mainly acetaldehyde) from the gas. The scrubbing liquid is neutralized in the neutralization tank and then sent to the wastewater treatment plant for treatment. The scrubbing tail gas is introduced into the falling film absorption tower and absorbs HCl with dilute hydrochloric acid absorbent to prepare a 31% hydrochloric acid solution. The remaining tail gas at the top of the falling film absorption tower is condensed in the condenser. The condensate waste liquid is neutralized in the neutralization tank and then discharged to the wastewater treatment plant for treatment. The non-condensable gas enters the water-washing alkaline scrubbing tower for washing, and the remaining tail gas is discharged into the atmosphere through a 30m exhaust stack.

[0045] S6 Distillation: The secondary hydrogenated liquid enters the distillation column, the bottom temperature is 130-140℃, and the pressure is -0.09MPa. The top vapor phase (water vapor and acetic acid vapor) of the distillation column enters the second condenser, and the bottom liquid phase of the distillation column is crude chloroacetic acid product.

[0046] S7 Distillation: Crude chloroacetic acid product enters the distillation column, with a bottom temperature of 140-150℃ and a pressure of -0.09MPa. The vapor phase at the top of the distillation column is chloroacetic acid vapor, which enters the solution preparation process and is prepared into a 69% concentration chloroacetic acid solution before being sent to the tank area for external sale. The bottom of the distillation column is high-boiling-point heavy component hazardous waste.

[0047] The liquid material following the hydrogenation reaction enters a vacuum distillation column. Its main component is chloroacetic acid, along with a mixture of reaction-generated water, incompletely converted acetic acid, low-carbon aldehydes, and high-boiling-point heavy components. Water and acetic acid are distilled out as vapors from the top of the column. The water vapor and acetic acid vapor enter a second condenser, where chilled water is used as the condensing medium. The condensation temperature is 20-65°C. The condensate (water and acetic acid) is recycled back to the chlorination reactor. The bottom material of the vacuum distillation column enters a vacuum distillation column.

[0048] Chloroacetic acid is separated from the top of the vacuum distillation column as vapor. This vapor enters the solution preparation process, where a 69% chloroacetic acid solution is prepared and sent to the tank farm for sale. The high-boiling-point liquid from the bottom of the vacuum distillation column is discharged into a heavy component intermediate tank and a neutralization tank for acid-base neutralization before being discharged into a transfer container. A qualified hazardous waste treatment plant is then contacted for transportation and disposal.

[0049] The specific application of the above scheme to improve the production process of a certain chloroacetic acid:

[0050] Taking a certain company as an example, this company mainly studies the reaction of acetic acid and acetic anhydride with liquid chlorine transported through pipelines in a chlorination reactor. The reactants, in liquid phase, enter a hydrogenation reactor and react with hydrogen gas from a chlor-alkali unit. In the hydrogenation reactor, which carries a palladium-on-carbon catalyst, dichloroacetic acid in the material is reduced to chloroacetic acid. The hydrogenated material is then processed in a vacuum distillation column. The light components, such as acetic acid, are distilled off at the top of the column and returned to the chlorination reactor for recycling. The crude product from the bottom of the column enters a distillation column to distill off the distillate. Pure chloroacetic acid is obtained at the top of the vacuum distillation column, while the bottom contains high-boiling-point heavy component waste. The pure chloroacetic acid is sent to a chloroacetic acid solution preparation tank to prepare a 69% concentration chloroacetic acid solution, which is then sent to the tank farm for sale as a product. The high-boiling-point heavy component waste is discharged into a heavy component intermediate tank and a neutralization tank for acid-base neutralization before being discharged into a transfer container. A qualified hazardous waste treatment plant is then contacted for transportation and disposal.

[0051] The company's expected results include a 0.34% reduction in annual raw material consumption, a 0.4% increase in annual product yield, an annual energy saving (per unit) of 1,200 tons of standard coal, a 50-ton reduction in carbon dioxide emissions, a reduction in unit product energy consumption, a 100-ton reduction in the annual processing of heavy components, and a 10% reduction in environmental protection costs.

[0052] After the company completed its research, it improved the product yield in the chloroacetic acid reaction process, with an acetic acid conversion rate of ≥85%, while ensuring a product qualification rate of ≥99%, which can meet production needs. At the same time, it significantly improved production safety and reduced hazardous waste generation by ≥25%.

[0053] The company achieved excellent results after eight months of experimental implementation in its production workshop. Under stable full-load operation of the production system, online sampling, analysis, measurement, and customer application validated the output effects of different processes. The application of this technology has provided direction for future production processes, ensuring safe development, qualified product quality, and achieving the expected yield for selective reduction of chloroacetic acid.

Claims

1. A green production process for chloroacetic acid, wherein the production process is a continuous chlorination method, comprising a reaction stage and a post-treatment stage, characterized in that: The reaction phase includes the following steps: S1 Chlorination reaction: Acetic acid and acetic anhydride are introduced into the chlorination reactor, and liquid chlorine is added to carry out the chlorination reaction; S2 stripping hydrolysis: The reactants after chlorination are fed into the acetyl chloride stripping tower, where they are separated into gas and liquid phases. The liquid phase from the acetyl chloride stripping tower flows by gravity into the hydrolysis reactor, where the acetyl chloride in the liquid phase after stripping is hydrolyzed into acetic acid and hydrochloric acid. S3 Hydrolysis Tail Gas Treatment: In the hydrolysis reactor, the reaction produces a hydrolysis gas phase and a hydrolysis liquid phase. The hydrolysis gas phase enters the subsequent tail gas treatment process through an acetyl chloride stripping tower. S4 First-stage high-temperature hydrogenation: The liquid phase output from the hydrolysis reactor enters the first hydrogenation reactor, and the reaction yields the first-stage hydrogenated liquid; S5 Secondary Low-Temperature Hydrogenation: The primary hydrogenated liquid enters the second hydrogenation reactor, and the reaction yields the secondary hydrogenated liquid; The secondary hydrogenated liquid described in S6 enters the post-processing stage to obtain chloroacetic acid product.

2. The green production process for chloroacetic acid according to claim 1, characterized in that: The post-processing stage includes the following steps: S6 distillation: The secondary hydrogenated liquid enters the distillation column, the vapor phase at the top of the distillation column enters the second condenser, and the liquid phase at the bottom of the distillation column is crude chloroacetic acid product; S7 Distillation: Crude chloroacetic acid enters the distillation tower. The vapor phase at the top of the distillation tower is chloroacetic acid vapor, which enters the solution preparation process. After being prepared into a 69% concentration chloroacetic acid solution, it is sent to the tank area for sale as a product. The bottom of the distillation tower contains high-boiling-point heavy component hazardous waste.

3. The green production process for chloroacetic acid according to claim 1, characterized in that: The acetic acid inlet of the chlorination reactor is connected to the acetic acid pipeline at the liquid phase outlet of the acetyl chloride absorption tower. The acetic acid inlet of the acetyl chloride absorption tower is connected to the outlet of the acetic acid storage tank via an acetic acid pipeline. The acetic anhydride inlet of the chlorination reactor is connected to the outlet of the acetic anhydride storage tank via an acetic anhydride pipeline. The heat exchange port of the chlorination reactor is connected to the heat exchanger port. The filtrate inlet of the chlorination reactor is connected to the liquid chlorine pipeline. The outlet of the chlorination reactor is connected to the inlet of the acetyl chloride stripping tower. The acetic acid recovery port of the chlorination reactor is connected to the second condenser via an acetic acid recovery pipeline.

4. The green production process for chloroacetic acid according to claim 1, characterized in that: In the subsequent exhaust gas treatment process, the exhaust gas sequentially passes through an acetyl chloride absorption tower, a first hydrogen chloride scrubbing tower, a falling film absorption tower with a first condenser, and a water-washing alkaline scrubbing tower. The gas phase outlet of the acetyl chloride absorption tower is connected to the inlet of the first hydrogen chloride scrubbing tower via an exhaust gas pipeline. The outlet of the first hydrogen chloride scrubbing tower is connected to the inlet of the falling film absorption tower via an exhaust gas pipeline. The outlet of the falling film absorption tower is connected to the inlet of the first condenser via an exhaust gas pipeline. The gas phase outlet of the first condenser is connected to the inlet of the water-washing alkaline scrubbing tower. The first condenser is also equipped with a liquid phase outlet.

5. The green production process for chloroacetic acid according to claim 4, characterized in that: The condensation temperature of the first condenser is 20-30℃. The first condensate output from the first condenser enters the neutralization tank for neutralization treatment. The first non-condensable product output from the first condenser contains hydrogen chloride and chlorine gas. The first non-condensable product is used as tail gas for subsequent tail gas treatment processes.

6. The green production process for chloroacetic acid according to claim 3, characterized in that: The outlet of the acetyl chloride stripping tower is connected to the inlet of the hydrolysis reactor via a stripping liquid phase pipeline. The outlet of the hydrolysis liquid phase of the hydrolysis reactor is connected to the inlet of the first hydrogenation reactor via a hydrolysis liquid phase pipeline. The outlet of the hydrolysis gas phase of the hydrolysis reactor is connected to the gas phase inlet of the acetyl chloride stripping tower. The outlet of the first hydrogenation reactor is connected to the inlet of the hydrogenated liquid of the second hydrogenation reactor via a hydrogenation pipeline. The first hydrogenation reactor and the second hydrogenation reactor are each provided with a hydrogen inlet and connected to a hydrogen pipeline. The first hydrogenation reactor and the second hydrogenation reactor are also each provided with a nitrogen inlet and connected to a nitrogen pipeline. The outlet of the second hydrogenation reactor is connected to the inlet of the condensation stripping tower. The liquid phase outlet of the condensation stripping tower is connected to the distillation tower. The gas phase outlet of the condensation stripping tower is connected to the inlet of the second hydrogen chloride scrubbing tower. The gas phase outlet of the distillation tower is connected to the inlet of the second condenser. The liquid phase outlet of the distillation tower is connected to the inlet of the distillation tower. The distillation tower is provided with a gas phase outlet and a liquid phase outlet.

7. The green production process for chloroacetic acid according to claim 6, characterized in that: The condensation stripping tower is connected to the second hydrogenation reactor. The condensation stripping tower performs condensation stripping on the secondary hydrogenation liquid. The liquid phase of the condensed gas stripping tower enters the distillation tower, and the gas phase of the condensed gas stripping tower enters the second hydrogen chloride scrubbing tower for tail gas absorption. The second hydrogen chloride scrubbing tower is also connected to the falling film absorption tower. The remaining tail gas discharged from the second hydrogen chloride scrubbing tower enters the subsequent tail gas treatment process through the falling film absorption tower until it is vented.

8. The green production process for chloroacetic acid according to claim 1, characterized in that: In S1, the reaction temperature is 140-150℃, the pressure is 0.3-0.5MPa, the flow rate of acetic acid into the chlorination reactor is 1.1kmol / min, the flow rate of acetic anhydride into the chlorination reactor is 50mol / min, and the flow rate of liquid chlorine into the chlorination reactor is 1kmol / min.

9. The green production process for chloroacetic acid according to claim 1, characterized in that: In S4, the reaction temperature inside the first hydrogenation reactor is 140-150℃, the residence time is 60-90min, the pressure is 0.2-0.3MPa, and the hydrogen flow rate is 100-120L / min. A fixed bed carrying a palladium-carbon catalyst is set inside the first hydrogenation reactor. In step S5, the reaction temperature inside the second hydrogenation reactor is 100-110℃, the residence time is 60-90min, the pressure is 0.2-0.3MPa, and the hydrogen flow rate is 80-90 L / min. A fixed bed carrying a palladium-carbon catalyst is provided inside the second hydrogenation reactor.

10. A green production process for chloroacetic acid according to claim 2, characterized in that: In S6, the bottom temperature of the distillation column is 130-140℃, the pressure is -0.10~-0.08MPa, the top gas phase is water and acetic acid, and the condensation temperature of the second condenser is 20-65℃. In S7, the distillation column has a bottom temperature of 140-150℃ and a pressure of -0.10 to -0.08 MPa.

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