Process for continuously producing chloroethane by using byproduct hydrogen chloride

Abstract

The invention discloses a process for continuously producing chloroethane by using byproduct hydrogen chloride, which belongs to the field of chloroethane production, and comprises the following steps: (1) catalytic reaction: fully mixing hydrogen chloride and ethylene, and feeding the mixture into a reactor for reaction to generate a gas phase and a liquid phase; (2) multi-stage condensation: after the gas phase of the reactor is subjected to first-stage circulating water cooling condensation and second-stage refrigerant cooling, most of chloroethane is cooled to a crude product tank, and a small amount of residual chloroethane and hydrogen chloride enter the reactor through a compressor; and (3) recycling hydrogen chloride: a gas phase obtained by secondary condensation mainly comprises hydrogen chloride, and is recycled to the bottom of the reactor for continuous reaction after being pressurized by a compressor, the process flow is simple, the purity of chloroethane is high, the production consumption is low, and recycling and continuous production of chloroethane are realized.

Description

Technical Field

[0001] The invention relates to the field of ethyl chloride production, and in particular to a process for continuously producing ethyl chloride by utilizing by-product hydrogen chloride. Background Art

[0002] Ethyl chloride is mainly used in the synthesis of dye intermediates, fragrance intermediates, ethyl cellulose, antibacterial agents and pesticides, etc. At present, ethyl chloride mainly comes from by-product recovery method and synthesis method. The recovery method mainly comes from the by-products of synthesizing trichloroacetaldehyde and diethyl phosphite. The synthesis method mainly uses ethanol-hydrochloric acid method or ethanol-hydrogen chloride method to synthesize ethyl chloride. They are the main sources of ethyl chloride in my country, mainly involving the source of hydrogen chloride, catalytic system, synthesis process, separation and refining, production equipment and automatic control, etc.

[0003] Among them, the ethanol-hydrochloric acid method often uses zinc chloride as a catalyst and is carried out at a temperature of 110℃ to 145℃. This method consumes a lot of steam, produces a lot of wastewater, and has an unstable reaction system. It is mainly based on batch reactions and has low production efficiency. The ethanol-hydrogen chloride method often uses zinc chloride as a catalyst and is carried out at a temperature of 100 to 145℃. This method has a high ethanol conversion rate, greatly reduced wastewater, low energy consumption, and high yield, but it is basically carried out in a batch production mode, and the degree of continuous production is not high. Summary of the invention

[0004] The present invention aims at the deficiencies in the prior art and provides a new process for producing ethyl chloride by ethylene hydrochlorination. By-product hydrogen chloride is used as a raw material, ethylene and a catalyst are added, and a reaction is carried out in an ethyl chloride solution to produce ethyl chloride. The reaction gas phase is subjected to secondary condensation to obtain a crude ethyl chloride product. The hydrogen chloride gas is compressed and recycled to a reactor for further use. The crude ethyl chloride product is passed through a hydrogen chloride separation tower to remove hydrogen chloride and a reboiler separation tower to remove reboilers to obtain an ethyl chloride product. In order to solve the above technical problems, the present invention is solved by the following technical scheme.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A process for continuously producing ethyl chloride using by-product hydrogen chloride comprises the following steps: (1) Catalytic reaction: Hydrogen chloride and ethylene are fully mixed and then introduced into the reactor to react under the action of the catalyst to produce gas phase and liquid phase; (2) Multi-stage condensation: The gas phase of the reactor is cooled by circulating water in the first stage and then by refrigerant in the second stage, and most of the ethyl chloride is condensed into the crude product tank. The remaining small amount of ethyl chloride and hydrogen chloride gas is pressurized by the compressor and then returned to the reactor. (3) Recycling of hydrogen chloride: The gas phase condensed from the secondary stage is mainly hydrogen chloride, which is pressurized by a compressor and recycled to the bottom of the reactor for further reaction; (4) Ethyl chloride distillation: Crude ethyl chloride first passes through a light distillation tower to separate hydrogen chloride, and the ethyl chloride and heavy boiling products in the bottom of the tower then enter a heavy distillation tower. High-purity ethyl chloride is extracted from the top of the heavy distillation tower as a product; (5) Catalytic concentration: Part of the liquid phase is diverted from the forced circulation pipeline at the bottom of the reactor to the catalyst evaporator. The evaporator is heated to evaporate the catalyst. The ethyl chloride distilled from the top of the evaporator is recovered to the crude product tank.

[0006] Preferably, the gas phase inside the reactor faces upward and the liquid phase refluxes downward, and the gas and liquid phases fully contact and react in countercurrent in the ceramic filler to produce ethyl chloride gas, which is extracted from the top of the reactor.

[0007] Preferably, the gas phase at the top of the reactor is cooled by primary circulating water to condense most of the ethyl chloride, and most of the ethyl chloride is condensed into a separation tank, and the remaining gas phase is cooled by a secondary refrigerant into a crude product tank.

[0008] Preferably, a small amount of chlorine gas is introduced into the residual catalyst concentrated liquid in the catalyst evaporator to reduce the activity of ferrous chloride and then the ferrous chloride is sent to the bottom of the reactor for reuse.

[0009] Preferably, the catalyst concentrated liquid in the catalyst evaporator is reduced and the filtrate is recovered into the heavy component tank.

[0010] Preferably, the reboiling polymer in the bottom of the heavy-removal distillation tower is first discharged into a heavy-component tank and then recovered uniformly.

[0011] Preferably, hot water or steam is introduced into the jacket of the evaporator to concentrate and evaporate the catalyst.

[0012] Preferably, hydrogen chloride and ethylene are fully mixed by a spiral gas phase mixer before entering the reactor.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention produces ethyl chloride by reacting ethylene and hydrogen chloride under the action of a catalyst, and obtains the ethyl chloride product through corresponding technologies such as condensation, distillation, and concentration. The biggest highlight of this process is that it solves the separation and concentration of the catalyst and the separation of the reboiling polymer, so that the processes of reaction, condensation, distillation, separation, and concentration can achieve continuous and stable operation, overcoming the problems of low reactor conversion rate and shutdown due to excessive polymer ratio. Since the moisture content in the raw materials hydrogen chloride and ethylene is below 2ppm, no moisture is generated during the reaction process, so the entire system has low requirements on equipment materials. The process of the present invention not only reasonably utilizes the by-product hydrogen chloride, but also has a simple process flow, high purity of ethyl chloride, and low production consumption, and realizes the resource utilization and continuous production of ethyl chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below with reference to the accompanying drawings.

[0017] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be used for other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0018] Those skilled in the art should understand that, in the disclosure of the present invention, the directions or positions indicated by the terms "longitudinal", "lateral", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, which are only simplified descriptions for the convenience of describing the present invention, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the above terms should not be understood as limitations on the present invention.

[0019] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0020] See also Figure 1 A process for continuously producing ethyl chloride using by-product hydrogen chloride comprises the following steps: (1) Catalytic reaction: Hydrogen chloride and ethylene are fully mixed by a spiral gas phase mixer before entering the reactor to ensure that ethylene and hydrogen chloride gases are evenly distributed during the mixing process, reduce local concentration differences, and improve reaction efficiency. The water content of the raw materials hydrogen chloride and ethylene is below 2ppm, and no water is produced during the reaction process. Therefore, the entire system does not require high equipment materials. After mixing, they enter the reactor to react and produce gas and liquid phases. The gas phase in the reactor faces upward, and the liquid phase refluxes downward. The gas and liquid phases countercurrently contact and react in the ceramic filler to produce ethyl chloride gas, which is extracted from the top of the reactor.

[0021] (2) Multi-stage condensation: The gas phase of the reactor is cooled by the primary circulating water and the secondary refrigerant in succession, and most of the ethyl chloride is condensed into the crude product tank. The remaining small amount of ethyl chloride and hydrogen chloride gas are returned to the reactor after being pressurized by the compressor. Most of the ethyl chloride is condensed into a separation tank. The separation tank should have sufficient volume to accommodate most of the condensed ethyl chloride and be equipped with a liquid level control system to prevent overflow caused by excessive liquid level. The remaining gas phase is then cooled by the secondary refrigerant into the crude product tank. The secondary refrigerant further cools and condenses the remaining gas phase to improve the recovery rate of ethyl chloride.

[0022] (3) Recycling of hydrogen chloride: The gas phase condensed from the secondary stage is mainly hydrogen chloride, which is pressurized by a compressor and recycled to the bottom of the reactor for further reaction. The pressure of the hydrogen chloride gas is increased by a compressor to ensure that it can smoothly enter the bottom of the reactor to participate in the reaction.

[0023] (4) Ethyl chloride distillation: The crude ethyl chloride is first passed through a light fractionation tower to separate hydrogen chloride. The crude ethyl chloride mixture is heated to above its boiling point in the light fractionation tower to vaporize the components therein. The components are separated by using the difference in boiling points. The hydrogen chloride at the top of the tower is condensed by -22°C Freon. Part of it is recycled as the reflux liquid of the tower. Part of the gaseous hydrogen chloride and light component gas is returned to the compressor through a pipeline for compression and pressure increase, and then recycled into the reactor. The ethyl chloride and heavy boiling products in the bottom of the tower are then recycled into the heavy fractionation tower. High-purity ethyl chloride is extracted from the top of the heavy fractionation tower as a product. The heavy boiling polymers in the bottom of the heavy fractionation tower are first discharged into the heavy component tank and then recycled uniformly.

[0024] (5) Catalytic concentration: Part of the liquid phase is diverted from the forced circulation pipeline at the bottom of the reactor to the catalyst evaporator. The evaporator is heated to evaporate the catalyst. Hot water or steam is introduced into the jacket of the evaporator to evaporate the catalyst. The ethyl chloride distilled from the top of the evaporator is recovered to the crude product tank. A small amount of chlorine is introduced into the remaining catalyst concentrate in the catalyst evaporator to reduce the activity of ferrous chloride and then sent to the bottom of the reactor for reuse. The catalyst concentrate in the catalyst evaporator is reduced and the filtrate is recovered to the heavy component tank.

[0025] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A process for continuously producing ethyl chloride using by-product hydrogen chloride, characterized in that: The following steps are involved: (1) Catalytic reaction: Hydrogen chloride and ethylene are fully mixed and then introduced into the reactor to react under the action of the catalyst to produce gas phase and liquid phase; (2) Multi-stage condensation: The gas phase of the reactor is cooled by circulating water in the first stage and then by refrigerant in the second stage, and most of the ethyl chloride is condensed into the crude product tank. The remaining small amount of ethyl chloride and hydrogen chloride gas is pressurized by the compressor and then returned to the reactor. (3) Recycling of hydrogen chloride: The gas phase condensed from the secondary stage is mainly hydrogen chloride, which is pressurized by a compressor and recycled to the bottom of the reactor for further reaction; (4) Ethyl chloride distillation: Crude ethyl chloride first passes through a light distillation tower to separate hydrogen chloride, and the ethyl chloride and heavy boiling products in the bottom of the tower then enter a heavy distillation tower. High-purity ethyl chloride is extracted from the top of the heavy distillation tower as a product; (5) Catalytic concentration: Part of the liquid phase is diverted from the forced circulation pipeline at the bottom of the reactor to the catalyst evaporator. The evaporator is heated to evaporate the catalyst. The ethyl chloride distilled from the top of the evaporator is recovered to the crude product tank.

2. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 1, characterized in that: The gas phase inside the reactor faces upward and the liquid phase refluxes downward. The gas and liquid phases fully contact and react in countercurrent in the ceramic filler to produce ethyl chloride, and the gas phase is extracted from the top of the reactor.

3. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 1, characterized in that: The gas phase at the top of the reactor is cooled by primary circulating water to condense most of the ethyl chloride, and most of the ethyl chloride is condensed into a separation tank, and the remaining gas phase is cooled by a secondary refrigerant into a crude product tank.

4. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 1, characterized in that: A small amount of chlorine gas is introduced into the catalyst concentrated liquid remaining in the catalyst evaporator to reduce the activity of ferrous chloride, and then the ferrous chloride is sent to the bottom of the reactor for reuse.

5. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 4, characterized in that: The catalyst concentrated liquid in the catalyst evaporator is reduced and the filtrate is recovered into the heavy component tank.

6. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 5, characterized in that: The heavy-boiling polymer in the tower kettle of the de-heavy distillation tower is first discharged into a heavy component tank and then recovered uniformly.

7. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 1, characterized in that: Hot water or steam is introduced into the jacket of the evaporator to concentrate and evaporate the catalyst.

8. A process for continuously producing ethyl chloride using by-product hydrogen chloride according to claim 1, characterized in that: Hydrogen chloride and ethylene are fully mixed by a spiral gas phase mixer before entering the reactor.

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