Process and device for combined synthesis of sulfur dichloride and chloroacetic acid

Abstract

The invention belongs to the field of chemical technology production, and particularly relates to a process and a device for combined synthesis of sulfur dichloride and chloroacetic acid. The process for jointly synthesizing sulfur dichloride and chloroacetic acid comprises the following steps: adding concentrated sulfuric acid into a sulfur dichloride reactor, introducing chlorine gas and liquid sulfur, carrying out a heating reaction, condensing to obtain sulfur dichloride, introducing an uncondensed gas phase into a chloroacetic acid reactor, adding sulfur dichloride and acetic acid into the chloroacetic acid reactor, carrying out a reaction, and after the reaction is completed, carrying out reduced pressure distillation to obtain the sulfur dichloride and chloroacetic acid. Reaction liquid enters a chloroacetic acid crystallizer, finished chloroacetic acid is obtained through primary crystallization, uncrystallized mother liquor is cooled through a mother liquor tank and subjected to secondary crystallization, and dichloroacetic acid is obtained. According to the process for jointly synthesizing the sulfur dichloride and the chloroacetic acid, the sulfur dichloride and the chloroacetic acid are jointly produced, the reaction conversion rate is high, the utilization rate of chlorine is increased, the purity of the sulfur dichloride reaches 95% or above, and the purity of the chloroacetic acid reaches 99.90% or above; the invention also provides a device for combined synthesis of sulfur dichloride and chloroacetic acid.

Description

Technical Field

[0001] The invention belongs to the field of chemical technology production, and specifically relates to a process and a device for jointly synthesizing sulfur dichloride and chloroacetic acid. Background Art

[0002] Sulfur dichloride is an intermediate in the preparation of carbamate insecticides butylsulfuron and bensulfuron. It can also be used as a chlorinating agent in organic synthesis to manufacture acid anhydrides or organic acid chlorides and high-pressure lubricants. It can be used as an additive for cutting oils, a processing agent for vegetable oils (such as corn oil, cottonseed oil, soybean oil) in the oil and fat industry, and a disinfectant and bactericide.

[0003] Chloroacetic acid is an important organic chemical raw material and intermediate, widely used in many fields. It can be used to produce pesticides such as insecticides and herbicides, medicines such as caffeine and barbiturates, dyes such as indigo, and can also be used as a flame retardant for polyamides and a flame retardant and smoke suppressant in PVC. It is also used in the preparation of chemicals such as sodium carboxymethyl cellulose and ethylenediaminetetraacetic acid. It is also used in the fields of daily chemicals, rubber additives, etc.

[0004] Sulfur dichloride and chloroacetic acid are two important chemical agents with a wide range of applications and large market demand. The current process for synthesizing sulfur dichloride has the disadvantages of serious pollution and low production efficiency, while the production process for chloroacetic acid has the disadvantages of low synthesis efficiency, difficulty in refining the synthesized dichloroacetic acid, and high impurity content.

[0005] CN104098072A discloses a preparation method of sulfur dichloride by gas phase catalytic synthesis, wherein ferric chloride loaded granular activated carbon is used as a catalyst, sulfur dichloride and chlorine are used as reaction raw materials and carrier gas, and the vaporized chlorine and sulfur dichloride mixed gas enters a fixed bed reactor, and sulfur dichloride is prepared by gas phase catalytic method. A solid catalyst and a fixed bed reactor are used, and almost no catalyst residue is left in the product, and no post-processing steps such as catalyst separation are required. The sulfur dichloride content of the obtained product is greater than 90%, and the excess chlorine is recycled, and the operation is simple, continuous and stable, and the conversion rate is high. However, the method requires the use of catalyst activation, the reaction speed is unstable, and the sulfur dichloride content of the product is low, which has a great impact on subsequent use.

[0006] CN115245792A discloses a chloroacetic acid synthesis system and method, which uses chlorine and acetic acid as raw materials, acetic anhydride as a catalyst for reaction, and a long tubular reaction tube as a reactor. Gas and liquid two-phase materials enter from the bottom and flow out from the top, and the gas and liquid are in full contact without back mixing. The single-pass conversion rate of acetic acid is above 95.7%, and the purity of the crude chloroacetic acid product is above 99.5% after being rectified by a conventional rectification process. However, the process needs to introduce acetic anhydride as a catalyst, and the single-pass conversion rate of acetic acid is not high. The purity of the product obtained by the conventional rectification process is not as good as that of the crystallization process. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art, provide a process for the combined synthesis of sulfur dichloride and chloroacetic acid, use concentrated sulfuric acid as a medium, adopt a temperature-controlled reaction, and a cooling and condensing method, so that the purity of the sulfur dichloride product reaches more than 95%, and at the same time, dichloroacetic acid is added to chloroacetic acid to avoid the influence of chlorine entraining sulfur dichloride on the quality of the chloroacetic acid product, and at the same time, unreacted chlorine is used, the chlorine flow rate is small, and the generation of dichloroacetic acid is reduced. At the same time, the reaction temperature is controlled and the reaction is carried out at a relatively low reaction temperature, which greatly reduces the generation of dichloroacetic acid, and the purity of the finished chloroacetic acid reaches more than 99.90%; the present invention also provides a device for the combined synthesis of sulfur dichloride and chloroacetic acid.

[0008] The process for the combined synthesis of sulfur dichloride and chloroacetic acid of the present invention comprises the following steps: adding concentrated sulfuric acid to a sulfur dichloride reactor, introducing chlorine gas and liquid sulfur, performing a temperature-raising reaction, generating a mixed gas, and obtaining sulfur dichloride after condensation; the uncondensed gas phase enters a chloroacetic acid reactor through a mist collector; sulfur dichloride and acetic acid are added to the chloroacetic acid reactor for chlorination reaction; after the reaction is completed, the reaction liquid enters a chloroacetic acid crystallizer, and obtains finished chloroacetic acid after a first crystallization; and the uncrystallized mother liquor is cooled in a mother liquor tank for secondary crystallization to obtain dichloroacetic acid.

[0009] The parameters during the reaction of the sulfur dichloride reactor are: reaction temperature 80-95° C., reaction pressure 10-25 KPa.

[0010] The chlorine gas feeding amount is 70-75 L / h, and the liquid sulfur feeding amount is 62-66 g / h.

[0011] The amount of sulfur dichloride used in the chloroacetic acid reactor is 0.5wt.‰-1wt.‰ of the amount of acetic acid added, and the amount of acetic acid used is 90-100g / h.

[0012] The specific process of the chlorination reaction is as follows: the uncondensed gas phase enters the chloroacetic acid reactor through a mist collector, sulfur dichloride and acetic acid are added to the chloroacetic acid reactor for reaction, oxygen needs to be added to the inside of the chloroacetic acid reactor in the initial stage of the reaction, and after the pressure is increased to 15KPa, the tail gas regulating and monitoring device on the top of the chloroacetic acid reactor is adjusted to maintain the reactor pressure at 0.5-5KPa, and the temperature is controlled to react at 105-115°C, and after the tail gas emission of the chloroacetic acid reactor is significantly reduced, the gas in the chloroacetic acid reactor is vented, and the temperature is kept for 1h, and the reaction is terminated.

[0013] The specific process of obtaining the finished chloroacetic acid by the first crystallization is as follows: the reaction liquid after the chlorination reaction is completed enters the crystallizer and is cooled in stages, the temperature is cooled to 80°C in the first stage at a cooling rate of 5-7°C / h, the temperature is cooled to 68°C in the second stage at a cooling rate of 3-4°C / h, the temperature is cooled to 64°C in the third stage at a cooling rate of 1.5-2.5°C / h, the temperature is cooled to 56°C in the fourth stage at a cooling rate of 0.5-1°C / h, after cooling to 56°C, the uncrystallized mother liquor is discharged, and then the temperature is raised to melt all the crystals to obtain the finished chloroacetic acid.

[0014] The specific process of obtaining dichloroacetic acid through secondary crystallization is as follows: the uncrystallized mother liquor enters a mother liquor tank, is cooled, and then the uncrystallized liquid in the kettle is circulated to the chloroacetic acid reactor, the mother liquor tank is controlled to maintain a temperature of 30-40° C., and the dichloroacetic acid is obtained after all the crystals are melted.

[0015] The device for combined synthesis of sulfur dichloride and chloroacetic acid comprises a sulfur dichloride reactor, a sulfur dichloride condenser, a mist collector, a chloroacetic acid reactor, a chloroacetic acid crystallizer, a chloroacetic acid finished product tank, and a mother liquid tank. The sulfur dichloride reactor is connected to the sulfur dichloride condenser, the sulfur dichloride condenser is connected to the mist collector, the mist collector is connected to the chloroacetic acid reactor, the chloroacetic acid reactor is connected to the chloroacetic acid crystallizer, the chloroacetic acid crystallizer is connected to the chloroacetic acid finished product tank, and the chloroacetic acid crystallizer is connected to the mother liquid tank.

[0016] The top of the sulfur dichloride reactor is provided with a chlorine pipeline and a liquid sulfur pipeline inlet, the sulfur dichloride condenser is provided with a pipeline connected to the sulfur dichloride finished product tank, and the top of the chloroacetic acid reactor is provided with a pipeline connected to the acetic acid pipeline, the tail gas adjustment monitoring device and the oxygen pipeline.

[0017] The chloroacetic acid crystallizer is connected to a heat-conducting oil tank, the mother liquid tank is connected to a dichloroacetic acid tank, and the mother liquid tank is provided with a pipeline connected to a chloroacetic acid reactor.

[0018] Specifically, the process for the combined synthesis of sulfur dichloride and chloroacetic acid comprises the following steps: introducing 1000g of concentrated sulfuric acid (60% of the volume of the reactor) into a sulfur dichloride reactor, heating it to 85°C, adding chlorine and liquid sulfur at the same time, controlling the introduction amount of chlorine to 70-75L / h, the introduction amount of liquid sulfur to 64±2g / h, controlling the temperature of the sulfur dichloride reactor to 80-95°C, the reaction pressure to 10-25KPa, condensing the gas phase coming out of the sulfur dichloride reactor through a sulfur dichloride condenser, and obtaining a liquid phase as a finished sulfur dichloride. , enter the sulfur dichloride finished product tank; the uncondensed gas phase passes through the wire mesh packing mist collector and enters the chloroacetic acid reactor through flow metering. The top of the chloroacetic acid reactor is connected to the acetic acid pipeline. The acetic acid feed rate is 90-100g / h. Sulfur dichloride is added to the chloroacetic acid reactor. The amount of sulfur dichloride added is 0.5wt.‰-1wt.‰ of the amount of acetic acid added. Oxygen is added to the chloroacetic acid reactor in the initial stage of the reaction. After the pressure is increased to 10-15KPa, the tail gas adjustment monitoring device at the top of the chloroacetic acid reactor is adjusted to keep the chloroacetic acid The pressure of the acid reactor is 0.5-5KPa, and the temperature of the chloroacetic acid reactor is controlled at 105℃-115℃. After the tail gas emission of the chloroacetic acid reactor decreases significantly, the gas in the chloroacetic acid reactor is vented and the temperature is kept for 1h. The crude product of the reaction is pressed into the chloroacetic acid crystallizer for cooling and crystallization. The temperature in the crystallizer is controlled by controlling the cooling capacity of the heat transfer oil heat exchanger: the temperature is cooled to 80℃ in the first stage, and the cooling rate is 5-7℃ / h; the temperature is cooled to 68℃ in the second stage, and the cooling rate is 3-4℃ / h; the temperature in the third stage is cooled to 80℃, and the cooling rate is 5-7℃ / h. The temperature is lowered to 64°C at a cooling rate of 1.5-2.5°C / h. In the fourth stage, the temperature is lowered to 56°C at a cooling rate of 0.5-1°C / h. After the temperature is lowered to 56°C, the uncrystallized mother liquor is discharged to the mother liquor tank, and then the temperature is raised to 80°C to melt all the crystals to obtain the finished chloroacetic acid and put it into the chloroacetic acid finished product tank; the mother liquor tank is first cooled to 5°C and maintained for 1.5h, and then the uncrystallized liquid in the kettle is circulated to the chloroacetic acid reactor, and the temperature of the mother liquor tank is controlled at 30-40°C. After all the crystals are melted, dichloroacetic acid is obtained and put into the dichloroacetic acid tank.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The process for the combined synthesis of sulfur dichloride and chloroacetic acid of the present invention uses concentrated sulfuric acid as a medium during the synthesis of sulfur dichloride, adopts a temperature-controlled reaction, and a cooling and condensing method, so that the purity of the sulfur dichloride product reaches more than 95%.

[0021] (2) The process for the combined synthesis of sulfur dichloride and chloroacetic acid of the present invention adds sulfur dichloride in the chloroacetic acid synthesis process, which effectively avoids the effect of chlorine entrained with sulfur dichloride on the quality of the chloroacetic acid product, and does not require the addition of common catalysts such as acetic anhydride; at the same time, the unreacted chlorine from sulfur dichloride is used in the chloroacetic acid synthesis process, the chlorine flow rate is small, and the acetic acid is relatively more, which further reduces the generation of the by-product dichloroacetic acid.

[0022] (3) The combined synthesis device and process of sulfur dichloride and chloroacetic acid of the present invention are combined to produce sulfur dichloride and chloroacetic acid together, and finally obtain a product with higher purity, improve the utilization rate of chlorine, have less by-products, and have higher production value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the device for combined synthesis of sulfur dichloride and chloroacetic acid in the present invention.

[0024] Figure 1 In: 1. Sulfur dichloride reactor; 2. Sulfur dichloride condenser; 3. Mist collector; 4. Chloroacetic acid reactor; 5. Chloroacetic acid crystallizer; 6. Chloroacetic acid finished product tank; 7. Mother liquor tank; 8. Sulfur dichloride finished product tank; 9. Dichloroacetic acid tank; 10. Heat transfer oil tank; 11. Chlorine pipeline; 12. Liquid sulfur pipeline; 13. Acetic acid pipeline; 14. Tail gas adjustment and monitoring device; 15. Oxygen pipeline. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments.

[0026] The raw materials used in the following examples are all commercially available products.

[0027] like Figure 1 As shown, the device used in the process of combined synthesis of sulfur dichloride and chloroacetic acid includes a sulfur dichloride reactor 1, a sulfur dichloride condenser 2, a mist collector 3, a chloroacetic acid reactor 4, a chloroacetic acid crystallizer 5, a chloroacetic acid finished product tank 6, and a mother liquid tank 7. The sulfur dichloride reactor 1 is connected to the sulfur dichloride condenser 2, the sulfur dichloride condenser 2 is connected to the mist collector 3, the mist collector 3 is connected to the chloroacetic acid reactor 4, the chloroacetic acid reactor 4 is connected to the chloroacetic acid crystallizer 5, the chloroacetic acid crystallizer 5 is connected to the chloroacetic acid finished product tank 6, and the chloroacetic acid crystallizer 5 is connected to the mother liquid tank 7.

[0028] The top of the sulfur dichloride reactor 1 is provided with a chlorine pipeline 11 and a liquid sulfur pipeline 12 inlet, the sulfur dichloride condenser 2 is provided with a pipeline connected to the sulfur dichloride finished product tank 8, and the top of the chloroacetic acid reactor 4 is provided with a pipeline connected to the acetic acid pipeline 13, the tail gas adjustment monitoring device 14 and the oxygen pipeline 15.

[0029] The chloroacetic acid crystallizer 5 is connected to the heat-conducting oil tank 10 , the mother liquid tank 7 is connected to the dichloroacetic acid tank 9 , and the mother liquid tank 7 is provided with a pipeline connected to the chloroacetic acid reactor 4 .

[0030] The following embodiments are all completed using the above-mentioned device.

[0031] Example 1

[0032] The process for the combined synthesis of sulfur dichloride and chloroacetic acid comprises the following steps:

[0033] 1000g of concentrated sulfuric acid is introduced into the sulfur dichloride reactor 1, and the temperature is raised to 85°C. Chlorine and liquid sulfur are added at the same time. The chlorine is controlled to be introduced at 70L / h, and the liquid sulfur is controlled to be introduced at 64±2g / h. The temperature of the sulfur dichloride reactor 1 is controlled to be 95°C, and the reaction pressure is 10KPa. The gas phase coming out of the sulfur dichloride reactor 1 is condensed through the sulfur dichloride condenser 2, and the liquid phase is the finished sulfur dichloride, which enters the sulfur dichloride finished product tank 8; the uncondensed gas phase passes through the wire mesh packing mist collector 3, and then enters the chloroacetic acid reactor 4 through flow metering. The top of the chloroacetic acid reactor 4 is connected to the acetic acid pipeline 13, and the acetic acid introduction is 90g / h. Sulfur dichloride is added to the chloroacetic acid reactor 4, and the amount of sulfur dichloride added is 0.5wt.‰ of the amount of acetic acid added. Oxygen is added to the chloroacetic acid reactor 4 in the initial stage of the reaction. After the pressure is raised to 10KPa, the tail gas adjustment monitoring device 14 at the top of the chloroacetic acid reactor is adjusted to keep the pressure of the chloroacetic acid reactor 4 at 5KPa to control the chloroacetic acid reaction. The temperature of the reactor 4 is controlled at 105°C. After the tail gas emission of the chloroacetic acid reactor 4 decreases significantly, the gas in the chloroacetic acid reactor 4 is vented and kept warm for 1 hour. The crude product after the reaction is pressed into the chloroacetic acid crystallizer 5 for cooling and crystallization. The temperature in the crystallizer is controlled by controlling the cooling capacity of the heat transfer oil heat exchanger: the temperature is cooled to 80°C in the first stage at a cooling rate of 5°C / h, the temperature is cooled to 68°C in the second stage at a cooling rate of 3°C / h, and the temperature is cooled to 64°C in the third stage at a cooling rate of 2.5℃ / h, the fourth stage is cooled to 56℃, the cooling rate is 0.8℃ / h, after cooling to 56℃, the uncrystallized mother liquor is discharged to the mother liquor tank 7, then the temperature is raised to 80℃, the crystals are completely melted, the finished chloroacetic acid is put into the chloroacetic acid finished product tank 6; the mother liquor tank 7 is first cooled to 5℃, maintained for 1.5h, and then the uncrystallized liquid in the kettle is circulated to the chloroacetic acid reactor 4, the temperature of the mother liquor tank 7 is controlled at 30℃, and the crystals are completely melted to obtain dichloroacetic acid and put into the dichloroacetic acid tank 9. After testing, the purity of the finished sulfur dichloride reached 96.1%, and the purity of the finished chloroacetic acid reached 99.93%.

[0034] Example 2

[0035] The process for the combined synthesis of sulfur dichloride and chloroacetic acid comprises the following steps: introducing 1000g of concentrated sulfuric acid into a sulfur dichloride reactor 1, heating the temperature to 85°C, adding chlorine and liquid sulfur at the same time, controlling the introduction amount of chlorine to 73L / h, controlling the introduction amount of liquid sulfur to 64±2g / h, controlling the temperature of the sulfur dichloride reactor to 90°C, and the reaction pressure to 15KPa; condensing the gas phase coming out of the sulfur dichloride reactor 1 through a sulfur dichloride condenser 2, and the liquid phase is a finished sulfur dichloride, which enters a sulfur dichloride finished product tank 8; the uncondensed gas phase passes through a wire mesh packing mist collector 3, and then enters a chloroacetic acid reactor 4 through flow metering; the top of the chloroacetic acid reactor 4 is connected to an acetic acid pipeline 13, the introduction amount of acetic acid is 95g / h, sulfur dichloride is added into the chloroacetic acid reactor 4, and the amount of sulfur dichloride added is 0.8wt.‰ of the amount of acetic acid added; oxygen is added into the chloroacetic acid reactor 4 at the initial stage of the reaction, and after the pressure is increased to 13KPa, adjusting the tail gas regulating and monitoring device 14 at the top of the chloroacetic acid reactor 4 to keep the pressure of the chloroacetic acid reactor 4 at 0 .5KPa, control the temperature of chloroacetic acid reactor 4 at 108℃, after the tail gas emission of chloroacetic acid reactor 4 decreases significantly, vent the gas in chloroacetic acid reactor 4 and continue to keep warm for 1h; press the crude product into chloroacetic acid crystallizer 5 for cooling and crystallization; control the temperature in chloroacetic acid crystallizer 5 by controlling the cooling capacity of heat transfer oil heat exchanger: cool to 80℃ in the first stage, cooling rate is 7℃ / h, cool to 68℃ in the second stage, cooling rate is 4℃ / h, cool to 100℃ in the third stage, cool to 200℃ in the third stage, ...200℃ in the third stage, cool to 300℃ in the third stage, cool to 400℃ in the third stage, cool to 500℃ in the third stage, cool to 600℃ in the third stage, cool to 800℃ in the first stage, cooling rate is 7℃ / h, cool to 680℃ in the third stage, cool to 600℃ in the third stage, cool to 500℃ in the third stage, cool to 500℃ in the third stage, cool to 800℃ in the third stage, cool to 600℃ in the third stage, cool to 500℃ in the third stage, cool to 800℃ in the third stage, cool to 600℃ in the third stage, cool to 500℃ in the third stage, cool to 800℃ in the third stage, cool to 800℃ in the third stage, cool to 600℃ in the third stage, cool to 500℃ in the third stage, cool to 500℃ in the third stage, cool to 800℃ To 64°C, the cooling rate is 1.5°C / h, the fourth stage is cooled to 56°C, the cooling rate is 0.5°C / h, after cooling to 56°C, the uncrystallized mother liquor is discharged to the mother liquor tank 7, then the temperature is raised to 80°C, the crystals are completely melted, the finished chloroacetic acid is put into the chloroacetic acid finished product tank 6; the mother liquor tank 7 is first cooled to 5°C, maintained for 2h, and then the uncrystallized liquid in the kettle is circulated to the chloroacetic acid reactor 4, the temperature of the mother liquor tank 7 is controlled at 35°C, and the crystals are completely melted to obtain dichloroacetic acid and put into the dichloroacetic acid tank 9. After testing, the purity of the finished sulfur dichloride reached 95.7%, and the purity of the finished chloroacetic acid reached 99.96%.

[0036] Example 3

[0037] The process for the combined synthesis of sulfur dichloride and chloroacetic acid comprises the following steps: introducing 1000g of concentrated sulfuric acid into a sulfur dichloride reactor 1, heating the temperature to 85°C, adding chlorine and liquid sulfur at the same time, controlling the introduction amount of chlorine to 75L / h, controlling the introduction amount of liquid sulfur to 64±2g / h, controlling the temperature of the sulfur dichloride reactor 1 to 80°C, and the reaction pressure to 25KPa; the gas phase coming out of the sulfur dichloride reactor 1 is condensed through a sulfur dichloride condenser 2, and the liquid phase is a finished sulfur dichloride, which enters a sulfur dichloride finished product tank 8; the uncondensed gas phase passes through a wire mesh packing mist collector 3, and then enters a chloroacetic acid reactor 4 through flow metering; the top of the chloroacetic acid reactor 4 is connected to an acetic acid pipeline 13, the introduction amount of acetic acid is 100g / h, sulfur dichloride is added into the chloroacetic acid reactor 4, and the amount of sulfur dichloride added is 1wt.‰ of the amount of acetic acid added; oxygen is added into the chloroacetic acid reactor 4 at the initial stage of the reaction, and after the pressure is increased to 15KPa, the tail gas regulating and monitoring device 14 at the top of the chloroacetic acid reactor 4 is adjusted to keep the pressure of the chloroacetic acid reactor 4 at 15000g / h. The pressure is 5KPa, and the temperature of the chloroacetic acid reactor 4 is controlled at 115°C. After the tail gas emission of the chloroacetic acid reactor 4 decreases significantly, the gas in the chloroacetic acid reactor 4 is vented and the temperature is kept warm for 2 hours; the crude product after the reaction is pressed into the chloroacetic acid crystallizer 5 for cooling and crystallization treatment; the temperature in the chloroacetic acid crystallizer 5 is controlled by controlling the cooling capacity of the heat transfer oil heat exchanger: the temperature is cooled to 80°C in the first stage, the cooling rate is 6°C / h, the temperature is cooled to 68°C in the second stage, the cooling rate is 3°C / h, and the temperature in the third stage is cooled to 80°C at a cooling rate of 6°C / h. The temperature is lowered to 64°C at a rate of 2°C / h. In the fourth stage, the temperature is lowered to 56°C at a rate of 1°C / h. After the temperature is lowered to 56°C, the uncrystallized mother liquor is discharged to the mother liquor tank 7, and then the temperature is raised to 80°C to melt all the crystals to obtain the finished chloroacetic acid and put it into the chloroacetic acid finished product tank 6; the mother liquor tank 7 is first cooled to 5°C and maintained for 1h, and then the uncrystallized liquid in the kettle is circulated to the chloroacetic acid reactor 4, and the temperature of the mother liquor tank 7 is controlled at 40°C. After all the crystals are melted, dichloroacetic acid is obtained and put into the dichloroacetic acid tank 9. After testing, the purity of the finished sulfur dichloride reaches 96.8%, and the purity of the finished chloroacetic acid reaches 99.91%.

[0038] According to the above implementation cases, according to the combined process of the present invention, referring to the above process control indicators, the finished product sulfur dichloride with a purity of more than 95% and the finished product chloroacetic acid with a purity of more than 99.90% can be produced.

Claims

1. A process for the combined synthesis of sulfur dichloride and chloroacetic acid, characterized in that: Concentrated sulfuric acid is added to a sulfur dichloride reactor, and chlorine and liquid sulfur are introduced to react at a high temperature to generate a mixed gas, which is condensed to obtain sulfur dichloride. The uncondensed gas phase enters a chloroacetic acid reactor through a mist collector, and sulfur dichloride and acetic acid are added to the chloroacetic acid reactor for chlorination reaction. After the reaction is completed, the reaction liquid enters a chloroacetic acid crystallizer, and the finished chloroacetic acid is obtained through the first crystallization. The uncrystallized mother liquor is cooled in a mother liquor tank for secondary crystallization to obtain dichloroacetic acid.

2. The process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 1, characterized in that: The parameters during the reaction of the sulfur dichloride reactor are: reaction temperature 80-95° C., reaction pressure 10-25 KPa.

3. The process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 1, characterized in that: The chlorine gas feeding amount is 70-75 L / h, and the liquid sulfur feeding amount is 62-66 g / h.

4. The process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 1, characterized in that: The amount of sulfur dichloride used in the chloroacetic acid reactor is 0.5wt.‰-1wt.‰ of the amount of acetic acid added.

5. The process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 1, characterized in that: The specific process of the chlorination reaction is as follows: the uncondensed gas phase enters the chloroacetic acid reactor through a mist collector, sulfur dichloride and acetic acid are added into the chloroacetic acid reactor for reaction, oxygen needs to be added into the chloroacetic acid reactor in the initial stage of the reaction, after the pressure is increased to 10-15KPa, the tail gas regulating and monitoring device on the top of the chloroacetic acid reactor is adjusted to keep the reactor pressure at 0.5-5KPa, the temperature is controlled at 105-115°C for reaction, and after the tail gas emission of the chloroacetic acid reactor is significantly reduced, the gas in the chloroacetic acid reactor is vented, the temperature is kept continuously, and the reaction is terminated.

6. The process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 1, characterized in that: The specific process of obtaining the finished chloroacetic acid by the first crystallization is as follows: the reaction liquid after the chlorination reaction is completed enters the crystallizer and is cooled in stages, the temperature is cooled to 80°C in the first stage at a cooling rate of 5-7°C / h, the temperature is cooled to 68°C in the second stage at a cooling rate of 3-4°C / h, the temperature is cooled to 64°C in the third stage at a cooling rate of 1.5-2.5°C / h, the temperature is cooled to 56°C in the fourth stage at a cooling rate of 0.5-1°C / h, after cooling to 56°C, the uncrystallized mother liquor is discharged, and then the temperature is raised to melt all the crystals to obtain the finished chloroacetic acid.

7. The process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 1, characterized in that: The specific process of obtaining dichloroacetic acid through secondary crystallization is as follows: the uncrystallized mother liquor enters a mother liquor tank, is cooled, and then the uncrystallized liquid in the kettle is circulated to the chloroacetic acid reactor, the mother liquor tank is controlled to maintain a temperature of 30-40° C., and the dichloroacetic acid is obtained after all the crystals are melted.

8. A device used in the process for combined synthesis of sulfur dichloride and chloroacetic acid according to any one of claims 1 to 7, characterized in that: The invention comprises a sulfur dichloride reactor (1), a sulfur dichloride condenser (2), a mist collector (3), a chloroacetic acid reactor (4), a chloroacetic acid crystallizer (5), a chloroacetic acid finished product tank (6), and a mother liquid tank (7). The sulfur dichloride reactor (1) is connected to the sulfur dichloride condenser (2), the sulfur dichloride condenser (2) is connected to the mist collector (3), the mist collector (3) is connected to the chloroacetic acid reactor (4), the chloroacetic acid reactor (4) is connected to the chloroacetic acid crystallizer (5), the chloroacetic acid crystallizer (5) is connected to the chloroacetic acid finished product tank (6), and the chloroacetic acid crystallizer (5) is connected to the mother liquid tank (7).

9. The device used in the process for the combined synthesis of sulfur dichloride and chloroacetic acid according to claim 8 is characterized in that: The top of the sulfur dichloride reactor (1) is provided with inlets for a chlorine pipeline (11) and a liquid sulfur pipeline (12); the sulfur dichloride condenser (2) is provided with a pipeline connected to a sulfur dichloride finished product tank (8); and the top of the chloroacetic acid reactor (4) is provided with a pipeline connected to an acetic acid pipeline (13), a tail gas regulating and monitoring device (14) and an oxygen pipeline (15).

10. The device used in the process for combined synthesis of sulfur dichloride and chloroacetic acid according to claim 8, characterized in that: The chloroacetic acid crystallizer (5) is connected to a heat-conducting oil tank (10), the mother liquid tank (7) is connected to a dichloroacetic acid tank (9), and the mother liquid tank (7) is provided with a pipeline connected to a chloroacetic acid reactor (4).

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