Cyclic utilization system for cryogenic purification of hydrogen chloride

Abstract

The utility model discloses a recycling system for cryogenic purification of hydrogen chloride. The recycling system comprises an activated carbon adsorption tower, a hydrogen chloride cooler, a hydrogen chloride buffer tank, a hydrogen chloride heater and a fluidized bed reactor, a gas outlet of the activated carbon adsorption tower is communicated with a tube pass inlet of the hydrogen chloride cooler, a tube pass outlet of the hydrogen chloride cooler is communicated with an inlet of the hydrogen chloride buffer tank, and an outlet of the hydrogen chloride buffer tank is communicated with a tube pass inlet of the hydrogen chloride heater through a first conveying pipeline; a tube pass outlet of the hydrogen chloride heater is communicated with a gas inlet of the fluidized bed reactor through a second conveying pipeline; and the top of the hydrogen chloride buffer tank is communicated with a gas discharge pipeline.

Description

Technical field:

[0001] The utility model relates to the technical field of polysilicon preparation, in particular to a hydrogen chloride deep-cold purification and recycling system. Background technology:

[0002] Trichlorosilane is the basic raw material for preparing polysilicon. The preparation process of polysilicon is to mix trichlorosilane and hydrogen and then pass them into a reduction furnace to react and deposit polysilicon on a silicon core at 1100 degrees Celsius. Usually, hydrogen and chlorine are first reacted in a chlor-alkali device to synthesize hydrogen chloride gas, and then the silicon powder and dry hydrogen chloride gas are sent to a fluidized bed reactor for fluidized reaction to prepare trichlorosilane. Therefore, the preparation of trichlorosilane depends on the continuous supply of hydrogen chloride gas from the chlor-alkali device.

[0003] During the preparation of polysilicon, the exhaust gas discharged from the reduction furnace contains a large amount of chlorosilane, hydrogen, hydrogen chloride and other components. When the exhaust gas is treated, it is first pressurized, cooled and condensed, and trichlorosilane is condensed into liquid. Hydrogen chloride, hydrogen and a small amount of uncondensed chlorosilane are sent to the exhaust gas washing tower and sprayed with a large amount of water for absorption. Hydrogen chloride is dissolved in water, and the hydrogen chloride aqueous solution is neutralized with sodium hydroxide and discharged after meeting the standards.

[0004] The above process has the following problems: 1. The tail gas treatment does not reuse hydrogen chloride and hydrogen, resulting in a waste of resources. 2. Chlorosilane in the tail gas reacts with water to generate water-insoluble silicon dioxide and hydrochloric acid, making the treatment of waste liquid more difficult. 3. The existing trichlorosilane preparation process is not designed with a chlor-alkali device, and it is impossible to synthesize hydrogen chloride gas by reacting hydrogen and chlorine. The plant area needs to rebuild the chlor-alkali device, which has high equipment investment costs and occupies a large space. Utility model content:

[0005] The utility model aims to provide a hydrogen chloride deep-cold purification and recycling system, which solves the problem of high equipment investment cost and large space occupied when rebuilding a chlor-alkali device in a factory area.

[0006] The purpose of the utility model is implemented by the following technical scheme: a hydrogen chloride deep-cold purification and recycling system, which includes an activated carbon adsorption tower, a hydrogen chloride cooler, a hydrogen chloride buffer tank, a hydrogen chloride heater and a fluidized bed reactor;

[0007] The gas outlet of the activated carbon adsorption tower is communicated with the tube-side inlet of the hydrogen chloride cooler, the tube-side outlet of the hydrogen chloride cooler is communicated with the inlet of the hydrogen chloride buffer tank, the outlet of the hydrogen chloride buffer tank is communicated with the tube-side inlet of the hydrogen chloride heater through a first delivery pipeline, the tube-side outlet of the hydrogen chloride heater is communicated with the gas inlet of the fluidized bed reactor through a second delivery pipeline; the top of the hydrogen chloride buffer tank is connected with a gas discharge pipeline.

[0008] Preferably, a temperature sensor is provided on the second delivery pipeline, a flow regulating valve is provided on the first delivery pipeline, the temperature sensor is electrically connected to an input end of a controller, and an output end of the controller is electrically connected to the flow regulating valve.

[0009] Preferably, it also includes a spare tank body, the bottom of the hydrogen chloride buffer tank is connected to the inlet of the spare tank body through a pipeline, a solenoid valve is provided on the pipeline connecting the bottom of the hydrogen chloride buffer tank with the inlet of the spare tank body, the side wall of the spare tank body is connected to the upper part of the hydrogen chloride buffer tank through a pipeline, and a delivery pump is provided on the pipeline connecting the side wall of the spare tank body with the upper part of the hydrogen chloride buffer tank.

[0010] Preferably, a liquid level sensor is provided in the hydrogen chloride buffer tank, the liquid level sensor is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the solenoid valve and the delivery pump respectively.

[0011] Preferably, the shell-side inlet of the hydrogen chloride cooler is connected to a refrigerant liquid inlet pipeline, and the shell-side outlet of the hydrogen chloride cooler is connected to a refrigerant liquid outlet pipeline.

[0012] Preferably, the shell-side inlet of the hydrogen chloride heater is connected to a heat medium liquid inlet pipeline, and the shell-side outlet of the hydrogen chloride heater is connected to a heat medium liquid outlet pipeline.

[0013] The utility model has the following advantages: the utility model is provided with an activated carbon adsorption tower, a hydrogen chloride cooler, a hydrogen chloride buffer tank and a hydrogen chloride heater; the activated carbon adsorption tower is used to adsorb a small amount of unliquefied chlorosilane, so as to avoid using a large amount of water for spraying and absorption, avoid generating water-insoluble silicon dioxide, and reduce the difficulty of treating waste liquid; the hydrogen chloride gas is first liquefied and then vaporized through the hydrogen cooler, the hydrogen chloride buffer tank and the hydrogen chloride heater, and the hydrogen gas is not liquefied, so as to achieve the purpose of separating hydrogen and hydrogen chloride, and the hydrogen gas is transported to a cold hydrogenation workshop through a gas discharge pipeline for recycling, and the hydrogen chloride gas is transported to a fluidized bed reactor for fluidized reaction with silicon powder to prepare trichlorosilane, so as to reasonably utilize hydrogen chloride and hydrogen, and there is no problem of waste of resources. At the same time, the utility model solves the problem that the existing preparation process of trichlorosilane has no supporting chlor-alkali device in design and cannot synthesize hydrogen chloride gas by reacting hydrogen and chlorine, so as to save equipment investment cost. Description of the drawings:

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creativity and labor.

[0015] Figure 1 It is a structural schematic diagram of the utility model.

[0016] Figure 2 It is a schematic diagram of the control principle of the utility model.

[0017] The components in the accompanying drawings are marked as follows: activated carbon adsorption tower 1, hydrogen chloride cooler 2, hydrogen chloride buffer tank 3, hydrogen chloride heater 4, fluidized bed reactor 5, spare tank body 6, refrigerant inlet pipeline 7, refrigerant outlet pipeline 8, first delivery pipeline 9, second delivery pipeline 10, heat medium inlet pipeline 11, heat medium outlet pipeline 12, gas discharge pipeline 13, temperature sensor 14, flow regulating valve 15, controller 16, solenoid valve 17, delivery pump 18, liquid level sensor 19. Specific implementation method:

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] like Figure 1-Figure 2 As shown, a hydrogen chloride deep-cold purification and recycling system comprises an activated carbon adsorption tower 1, a hydrogen chloride cooler 2, a hydrogen chloride buffer tank 3, a hydrogen chloride heater 4, a fluidized bed reactor 5 and a spare tank 6;

[0020] An activated carbon adsorption tower 1 is used to adsorb a small amount of unliquefied chlorosilane. The gas outlet of the activated carbon adsorption tower 1 is connected to the tube-side inlet of the hydrogen chloride cooler 2 through a pipeline. The tube-side outlet of the hydrogen chloride cooler 2 is connected to the inlet of the hydrogen chloride buffer tank 3 through a pipeline. The hydrogen chloride buffer tank 3 is used to store liquid hydrogen chloride. The shell-side inlet of the hydrogen chloride cooler 2 is connected to a refrigerant liquid inlet pipeline 7. The shell-side outlet of the hydrogen chloride cooler 2 is connected to a refrigerant liquid outlet pipeline 8. The hydrogen chloride cooler 2 uses -75°C R23 refrigerant as a heat exchange medium to cool the hydrogen chloride gas to liquefy the hydrogen chloride gas. Under the process conditions, hydrogen will not be liquefied, thereby achieving the purpose of separating hydrogen and hydrogen chloride.

[0021] The outlet of the hydrogen chloride buffer tank 3 is connected to the tube-side inlet of the hydrogen chloride heater 4 through a first delivery pipeline 9, and the tube-side outlet of the hydrogen chloride heater 4 is connected to the gas inlet of the fluidized bed reactor 5 through a second delivery pipeline 10. The fluidized bed reactor 5 fluidizes silicon powder and dry hydrogen chloride gas to prepare trichlorosilane; the top of the hydrogen chloride buffer tank 3 is connected to a gas discharge pipeline 13, and the non-condensable gas is transported to the cold hydrogenation workshop for recycling through the gas discharge pipeline 13; the shell-side inlet of the hydrogen chloride heater 4 is connected to a heat medium liquid inlet pipeline 11, and the shell-side outlet of the hydrogen chloride heater 4 is connected to a heat medium liquid outlet pipeline 12. The hydrogen chloride heater 4 uses hot steam as a heat exchange medium to heat the liquid hydrogen chloride to vaporize the liquid hydrogen chloride;

[0022] The second delivery pipeline 10 is provided with a temperature sensor 14, which detects the temperature of the hydrogen chloride gas. The temperature setting range of the hydrogen chloride gas is 50-80° C. The first delivery pipeline 9 is provided with a flow control valve 15, which controls the flow of liquid hydrogen chloride. The temperature sensor 14 is electrically connected to the input end of the controller 16, and the output end of the controller 16 is electrically connected to the flow control valve 15. When the temperature sensor 14 detects that the temperature of the hydrogen chloride gas exceeds or is lower than the set range, the controller 16 controls the opening of the flow control valve 15.

[0023] The bottom of the hydrogen chloride buffer tank 3 is connected to the inlet of the standby tank body 6 through a pipeline. A solenoid valve 17 is provided on the pipeline connecting the bottom of the hydrogen chloride buffer tank 3 and the inlet of the standby tank body 6. When the solenoid valve 17 is opened, the liquid hydrogen chloride in the hydrogen chloride buffer tank 3 is transported to the standby tank body 6. The standby tank body 6 is used to prevent the liquid hydrogen chloride in the hydrogen chloride buffer tank 3 from overflowing. The side wall of the standby tank body 6 is connected to the upper part of the hydrogen chloride buffer tank 3 through a pipeline. A delivery pump 18 is provided on the pipeline connecting the side wall of the standby tank body 6 and the upper part of the hydrogen chloride buffer tank 3. When the solenoid valve 17 is closed, the delivery pump 18 is started to transport the liquid hydrogen chloride in the standby tank body 6 back to the hydrogen chloride buffer tank 3.

[0024] A liquid level sensor 19 is provided in the hydrogen chloride buffer tank 3, and the liquid level of the liquid phase hydrogen chloride in the hydrogen chloride buffer tank 3 is detected by the liquid level sensor 19. The liquid level sensor 19 is electrically connected to the input end of the controller 16, and the output end of the controller 16 is electrically connected to the solenoid valve 17 and the delivery pump 18 respectively. When the liquid level sensor 19 detects that the liquid level of the liquid phase hydrogen chloride in the hydrogen chloride buffer tank 3 exceeds or is lower than the set range, the controller 16 controls the solenoid valve 17 and the delivery pump 18 to operate.

[0025] Working process: the tail gas discharged from the reduction furnace is first pressurized, cooled and condensed, and trichlorosilane is condensed into liquid, and the remaining hydrogen chloride, hydrogen and a small amount of uncondensed chlorosilane are sent to the activated carbon adsorption tower 1, and the activated carbon adsorption tower 1 is used to adsorb a small amount of unliquefied chlorosilane to separate the chlorosilane, and the remaining hydrogen chloride gas and hydrogen enter the tube side of the hydrogen chloride cooler 2. The shell side of the hydrogen chloride cooler 2 uses -75°C R23 refrigerant as a heat exchange medium to cool the hydrogen chloride gas and liquefy the hydrogen chloride gas. Under this process condition, the hydrogen will not be liquefied;

[0026] The liquid hydrogen chloride and hydrogen in the hydrogen chloride cooler 2 are stored in the hydrogen chloride buffer tank 3 through a pipeline, and the hydrogen is transported to the cold hydrogenation workshop for recycling through a gas discharge pipeline 13; a liquid level sensor 19 is provided in the hydrogen chloride buffer tank 3, and the liquid level of the liquid hydrogen chloride in the hydrogen chloride buffer tank 3 is detected by the liquid level sensor 19. When the liquid level sensor 19 detects that the liquid level of the liquid hydrogen chloride in the hydrogen chloride buffer tank 3 exceeds a set range, the controller 16 controls the solenoid valve 17 to open, the delivery pump 18 to stop, and the liquid hydrogen chloride in the hydrogen chloride buffer tank 3 enters the spare tank body 6 for temporary storage. When the liquid level sensor 19 detects that the liquid level of the liquid hydrogen chloride in the hydrogen chloride buffer tank 3 is lower than the set range, the controller 16 controls the solenoid valve 17 to close, the delivery pump 18 to start, and the liquid hydrogen chloride in the spare tank body 6 returns to the hydrogen chloride buffer tank 3 through the delivery pump 18;

[0027] The liquid hydrogen chloride in the hydrogen chloride buffer tank 3 enters the tube side of the hydrogen chloride heater 4 through the first delivery pipeline 9. The shell side of the hydrogen chloride heater 4 uses hot steam as a heat exchange medium to heat the liquid hydrogen chloride to vaporize the liquid hydrogen chloride. The vaporized hydrogen chloride gas enters the fluidized bed reactor 5 through the second delivery pipeline 10 to react with silicon powder in a fluidized state to generate trichlorosilane.

[0028] A temperature sensor 14 is provided on the second delivery pipeline 10, and the temperature of the hydrogen chloride gas is detected by the temperature sensor 14. When the temperature sensor 14 detects that the temperature of the hydrogen chloride gas exceeds a set range, the controller 16 controls the flow control valve 15 to open wider, increases the amount of liquid inlet into the pipe side of the hydrogen chloride heater 4, and reduces the temperature of the hydrogen chloride gas to within the set range; when the temperature sensor 14 detects that the temperature of the hydrogen chloride gas is lower than the set range, the controller 16 controls the flow control valve 15 to open narrower, reduces the amount of liquid inlet into the pipe side of the hydrogen chloride heater 4, and ensures that the temperature of the hydrogen chloride gas is always between 50-80°C.

[0029] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrogen chloride deep-cold purification and recycling system, characterized in that: It includes an activated carbon adsorption tower, a hydrogen chloride cooler, a hydrogen chloride buffer tank, a hydrogen chloride heater and a fluidized bed reactor; The gas outlet of the activated carbon adsorption tower is communicated with the tube-side inlet of the hydrogen chloride cooler, the tube-side outlet of the hydrogen chloride cooler is communicated with the inlet of the hydrogen chloride buffer tank, the outlet of the hydrogen chloride buffer tank is communicated with the tube-side inlet of the hydrogen chloride heater through a first delivery pipeline, the tube-side outlet of the hydrogen chloride heater is communicated with the gas inlet of the fluidized bed reactor through a second delivery pipeline; the top of the hydrogen chloride buffer tank is connected with a gas discharge pipeline.

2. A hydrogen chloride deep-cold purification and recycling system according to claim 1, characterized in that: The second delivery pipeline is provided with a temperature sensor, the first delivery pipeline is provided with a flow regulating valve, the temperature sensor is electrically connected to an input end of a controller, and an output end of the controller is electrically connected to the flow regulating valve.

3. A hydrogen chloride deep-cold purification and recycling system according to claim 2, characterized in that: It also includes a spare tank body, the bottom of the hydrogen chloride buffer tank is connected to the inlet of the spare tank body through a pipeline, a solenoid valve is arranged on the pipeline connecting the bottom of the hydrogen chloride buffer tank with the inlet of the spare tank body, the side wall of the spare tank body is connected to the upper part of the hydrogen chloride buffer tank through a pipeline, and a delivery pump is arranged on the pipeline connecting the side wall of the spare tank body with the upper part of the hydrogen chloride buffer tank.

4. A hydrogen chloride deep-cold purification and recycling system according to claim 3, characterized in that: A liquid level sensor is arranged in the hydrogen chloride buffer tank, and the liquid level sensor is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the solenoid valve and the delivery pump respectively.

5. A hydrogen chloride deep-cold purification and recycling system according to claim 1, characterized in that: The shell side inlet of the hydrogen chloride cooler is connected with a refrigerant liquid inlet pipeline, and the shell side outlet of the hydrogen chloride cooler is connected with a refrigerant liquid outlet pipeline.

6. A hydrogen chloride deep-cold purification and recycling system according to claim 1, characterized in that: The shell side inlet of the hydrogen chloride heater is connected with a heat medium liquid inlet pipeline, and the shell side outlet of the hydrogen chloride heater is connected with a heat medium liquid outlet pipeline.

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