Polycrystalline silicon cold hydrogenation reaction gas quenching system

Abstract

The utility model relates to the technical field of polycrystalline silicon processing, in particular to a polycrystalline silicon cold hydrogenation reaction gas quenching system which comprises a quenching tower, a quenching tank, a condenser and a slurry concentration tank, the top of the quench tower is provided with a first return pipeline communicated with the condenser, and the bottom of the quench tower is provided with a second return pipeline communicated with the quench tank; the quenching tank is communicated with the slurry concentration tank, the quenching tank is provided with an air inlet, and the air inlet is communicated with the cold hydrogenation reactor. According to the polycrystalline silicon cold hydrogenation reaction gas quenching device, the two towers are arranged for cooling, and the return pipelines are arranged in the quenching tower, the quenching tank and the condenser, so that the technical problems that the quenching tower is easy to block and the circulating pump is easy to damage to cause accidental shutdown in the existing polycrystalline silicon cold hydrogenation reaction gas quenching device are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon processing, in particular to a polysilicon cold hydrogenation reaction gas rapid cooling system. Background Art

[0002] The polysilicon production process produces toxic and corrosive byproduct silicon tetrachloride (STC). Currently, cold hydrogenation technology is mostly used to convert STC into trichlorosilane (TCS) under low temperature and high pressure. This not only avoids environmental pollution, but also TCS, as one of the important raw materials in polysilicon production, can be recycled in the production process, greatly reducing production costs.

[0003] The tail gas produced during the cold hydrogenation production of polysilicon includes silicon powder, metal chlorides, polymers, high boiling products and chlorosilane compounds, etc. In the prior art, the excess heat in the cold hydrogenation tail gas is removed by rapid cooling technology for recycling, and the solids in the reaction products are washed, precipitated and separated to remove impurities.

[0004] In the prior art, for example, publication number CN106430214A provides a quenching device and a quenching process for polysilicon synthesis. By setting a quenching tower, a condenser, a reflux tank and a circulating pump, impurities such as silicon powder, metal chlorides, polymers and high boiling points in the hydrogenation reaction gas during polysilicon synthesis can be removed, thereby reducing the amount of chlorosilane elution in the quenching tower and preventing particles such as silicon powder from clogging the quenching tower, thereby greatly extending the service life of the quenching tower.

[0005] However, the above-mentioned prior art still has the following problems: 1. Impurities in the cold hydrogenation reaction gas are still concentrated in the quenching tower for separation and washing, which will inevitably lead to blockage of the quenching tower; 2. When using a circulating pump, the silicon powder and corrosive components in the cold hydrogenation reaction gas can easily cause abrasion damage to the pump and cause the risk of unexpected shutdown. Utility Model Content

[0006] The utility model aims to provide a polysilicon cold hydrogenation reaction gas quenching system to solve the technical problems existing in the existing polysilicon cold hydrogenation reaction gas quenching device that the quenching tower is easy to be blocked and the circulating pump is easy to be damaged and cause unexpected shutdown.

[0007] In order to achieve the above-mentioned object, the utility model adopts the following technical scheme: a polysilicon cold hydrogenation reaction gas quenching system, including a quenching tower, a quenching tank, a condenser and a slurry concentration tank;

[0008] The top of the quench tower is provided with a first reflux pipeline connected to the condenser, and the bottom of the quench tower is provided with a second reflux pipeline connected to the quench tank;

[0009] The quench tank is communicated with the slurry concentration tank, and the quench tank is provided with an air inlet, which is communicated with the cold hydrogenation reactor.

[0010] Furthermore, the quenching tower also includes an STC feed port, a quenching tower filler and a quenching tower liquid collecting tank, wherein the STC feed port is arranged at the top of the quenching tower, the quenching tower filler is arranged in the middle of the quenching tower body, and the quenching tower liquid collecting tank is arranged at the bottom of the quenching tower body and is connected to the second reflux pipeline.

[0011] Furthermore, the quench tank also includes a cooling medium feed port, a quench tank filler and a high-efficiency gas distributor, the cooling medium feed port is respectively; the quench tank filler is placed in the middle of the quench tank, and the high-efficiency gas distributor is placed at the bottom of the quench tank and connected to the air inlet.

[0012] Furthermore, the condenser includes a tube layer and a shell layer, the tube layer is connected to a condensation pipeline; an air outlet is provided at the top of the shell layer, the air outlet is connected to a heat recovery system, and a condenser liquid collection tank is provided at the bottom of the shell layer, and the condenser liquid collection tank is connected to the first reflux pipeline.

[0013] Furthermore, the gas outlet is provided with a pipeline connected to the STC feed port, and the pipeline is provided with a valve.

[0014] Furthermore, an exhaust gas outlet is provided at the top of the slurry concentration tank, a circulating cooling water pipe is provided in the middle of the slurry concentration tank, a slurry outlet is provided at the bottom of the slurry concentration tank, and the slurry outlet is connected to a slurry treatment device; the exhaust gas outlet is connected to the slurry treatment device, and the exhaust gas outlet is also connected to a hydrogen inlet pipe.

[0015] Beneficial effects of the utility model:

[0016] 1) The utility model adopts a two-tower quenching technology. Compared with the prior art, a quenching tank is added. During separation, the cold hydrogenation reaction gas is first pre-cooled in the quenching tank, and the solid impurities and soluble metal chlorides entrained in the reaction gas are separated and settled to the bottom of the quenching tank through the quenching tank filler. Other impurities dissolved in the cold hydrogenation reaction gas enter the quenching tower through the second reflux pipeline and are separated by the quenching tower filler, such as aluminum chloride. The separated impurities will re-enter the quenching tank through the second reflux pipeline and be discharged to the slurry treatment device together with other impurities. This step-by-step quenching and impurity removal technology can effectively solve the blockage problem of the quenching tower.

[0017] 2) The utility model adds a slurry concentration tank, which can increase the solid concentration of the discharged slurry by collecting and storing the slurry discharged from the quench tank. When it is subsequently discharged to the slurry treatment device, the processing load of the device can be reduced, the processing capacity requirements of the slurry treatment device can be reduced, the device investment can be saved and energy consumption can be reduced.

[0018] 3) Compared with the existing quenching device and process, the utility model adds a quenching tank and a second reflux pipeline, and does not need to set a circulating pump, thus avoiding the risk of device shutdown due to abrasion damage of the circulating pump and improving the reliability and stability of the device operation.

[0019] 4) The condenser in the utility model adopts a vertical shell and tube heat exchanger, so that a condensation pipeline can be connected to the tube layer, and a first reflux pipeline connected to the shell layer is set to connect with the quenching tower. Compared with the prior art, the reflux tank and reflux pump are reduced, the investment in device equipment is reduced, and the integrity and stability of the system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The utility model is a structural schematic diagram of a polysilicon cold hydrogenation reaction gas rapid cooling system.

[0021] The markings in the attached drawings are as follows: quench tower 1, quench tank 2, condenser 3, slurry concentration tank 4, heat recovery system 5, slurry treatment device 6, hydrogen inlet pipe 7;

[0022] The first reflux pipeline 101, the second reflux pipeline 102, the STC feed port 103, the quench tower filler 104, the quench tower liquid collecting tank 105, the air inlet 201, the cooling medium feed port 202, the quench tank filler 203, the high-efficiency gas distributor 204, the condensation pipeline 301, the air outlet 302, the condenser liquid collecting tank 303, the valve 304, the exhaust gas outlet 401, the circulating cooling water pipe 402, and the slurry outlet 403. DETAILED DESCRIPTION

[0023] The following is further described in detail through specific implementation methods:

[0024] As attached Figure 1 As shown, the utility model provides a polysilicon cold hydrogenation reaction gas quenching system, comprising a quenching tower 1, a quenching tank 2, a condenser 3 and a slurry concentration tank 4. The top of the quenching tower 1 is provided with a first reflux pipeline 101 connected to the condenser 3, and the bottom of the quenching tower 1 is provided with a second reflux pipeline 102 connected to the quenching tank 2. The quenching tank 2 is connected to the slurry concentration tank 4, and the quenching tank 2 is provided with an air inlet 201, which is connected to the cold hydrogenation reactor, so that the reaction gas generated during the cold hydrogenation reaction enters the quenching system from the air inlet 201 for cooling.

[0025] The quench tower 1 also includes an STC feed port 103, a quench tower filler 104 and a quench tower liquid collecting tank 105. The STC feed port 103 is arranged at the top of the quench tower 1, and the STC feed port 103 is connected to the STC raw material tank for start-up through a pipeline. The quench tower filler 104 is arranged in the middle of the tower body of the quench tower 1, and the quench tower liquid collecting tank 105 is arranged at the bottom of the tower body of the quench tower 1 and is connected to the second reflux pipeline 102.

[0026] The quench tank 2 also includes a cooling medium feed port 202, a quench tank filler 203 and a high-efficiency gas distributor 204. The cooling medium feed port 202 is connected to two pipelines, one from the STC evaporator slag discharge pipeline and the other from the slurry treatment silicon chloride recovery pipeline.

[0027] The quench tank filler 203 is placed in the middle of the quench tank 2. The quench tank filler 203 can promote the contact between the rising steam and the descending liquid. At the same time, the filler also helps to separate and precipitate the solid impurities entrained in the gas. The high-efficiency gas distributor 204 is placed at the bottom of the quench tank 2 and connected to the air inlet 201. This can help the gas entering the quench system from the air inlet 201 to be evenly distributed, and promote the contact between the gas and the liquid.

[0028] The condenser 3 is a vertical shell and tube heat exchanger, including a tube layer and a shell layer, and a condensation pipeline 301 is connected in the tube layer, and the condensation pipeline 301 is used to provide a cooling medium STC. A gas outlet 302 is provided at the top of the shell layer, and the gas outlet 302 is connected to a heat recovery system 5 for recovering the extra heat generated when the cold hydrogenation reaction gas is cooled. A condenser liquid collection tank 303 is provided at the bottom of the shell layer, and the condenser liquid collection tank 303 is connected to the first reflux pipeline 101 to provide reflux liquid for the liquid level in the quench tank 2.

[0029] The gas outlet 302 is provided with a pipeline connected to the STC feed port 103 , and a valve 304 is provided on the pipeline.

[0030] An exhaust gas outlet 401 is provided at the top of the slurry concentration tank 4, a circulating cooling water pipe 402 is provided in the middle of the slurry concentration tank 4, a slurry outlet 403 is provided at the bottom of the slurry concentration tank 4, and the slurry outlet 403 is connected to a slurry treatment device 6. The exhaust gas outlet 401 is connected to the condenser of the slurry treatment device 6, and the exhaust gas outlet 401 is also connected to a hydrogen inlet pipe 7, which is connected to a circulating hydrogen compressor for maintaining the gas pressure in the slurry concentration tank 4.

[0031] In summary, the utility model adopts a two-tower quenching technology. Compared with the prior art, a quenching tank 2 is added. During separation, the cold hydrogenation reaction gas is first pre-cooled in the quenching tank 2, and the solid impurities and soluble metal chlorides entrained in the reaction gas are separated and settled into the bottom of the quenching tank 2 through the quenching tank filler 203. Other impurities dissolved in the cold hydrogenation reaction gas enter the quenching tower 1 through the second reflux pipeline 102, and are separated under the action of the quenching tower filler 104, such as aluminum chloride. The separated impurities will re-enter the quenching tank 2 through the second reflux pipeline 102, and be discharged to the slurry treatment device together with other impurities. Such a step-by-step quenching and impurity removal technology can effectively solve the blockage problem of the quenching tower 1.

[0032] The utility model adds a slurry concentration tank 4, which can increase the solid concentration of the discharged slurry by collecting and storing the slurry discharged from the quench tank 2. When it is subsequently discharged to the slurry processing device 6, the processing load of the device can be reduced, the processing capacity requirements of the slurry processing device 6 are reduced, the device investment is saved and energy consumption can be reduced.

[0033] Compared with the existing quenching device and process, the utility model adds a quenching tank 2 and a second reflux pipeline 102, and does not need to set a circulating pump, thus avoiding the risk of device shutdown due to abrasion damage of the circulating pump and improving the reliability and stability of the device operation.

[0034] In the utility model, the condenser 3 adopts a vertical shell heat exchanger, so that a condensation pipeline 301 can be provided on the tube side, and a first reflux pipeline 101 is provided on the shell side to communicate with the quenching tower 1. Compared with the prior art, the reflux tank and the reflux pump are reduced, the investment in device equipment is reduced, and the reliability and stability of the system can be improved.

[0035] The above is only an embodiment of the utility model, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the utility model, several deformations and improvements can be made, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A polysilicon cold hydrogenation reaction gas quenching system, characterized in that: It comprises a quenching tower (1), a quenching tank (2), a condenser (3) and a slurry concentration tank (4); The top of the quenching tower (1) is provided with a first reflux pipeline (101) connected to the condenser (3), and the bottom of the quenching tower (1) is provided with a second reflux pipeline (102) connected to the quenching tank (2); The quenching tank (2) is connected to the slurry concentration tank (4), and the quenching tank (2) is provided with an air inlet (201), and the air inlet (201) is connected to the cold hydrogenation reactor.

2. A polysilicon cold hydrogenation reaction gas quenching system according to claim 1, characterized in that: The quenching tower (1) further comprises an STC feed inlet (103), a quenching tower filler (104) and a quenching tower liquid collecting tank (105); the STC feed inlet (103) is arranged at the top of the quenching tower (1); the quenching tower filler (104) is arranged in the middle of the quenching tower (1) body; and the quenching tower liquid collecting tank (105) is arranged at the bottom of the quenching tower (1) body and is connected to the second reflux pipeline (102).

3. A polysilicon cold hydrogenation reaction gas quenching system according to claim 2, characterized in that: The quench tank (2) further comprises a cooling medium feed inlet (202), a quench tank filler (203) and a high-efficiency gas distributor (204), wherein the cooling medium feed inlet (202) is respectively; the quench tank filler (203) is placed in the middle of the quench tank (2), and the high-efficiency gas distributor (204) is placed in the bottom of the quench tank (2) and is connected to the gas inlet (201).

4. A polysilicon cold hydrogenation reaction gas quenching system according to claim 3, characterized in that: The condenser (3) comprises a tube layer and a shell layer, and the tube layer is connected to a condensation pipeline (301); The top of the shell layer is provided with an air outlet (302), the air outlet (302) is connected to a heat recovery system (5), and the bottom of the shell layer is provided with a condenser liquid collection tank (303), the condenser liquid collection tank (303) is connected to the first reflux pipeline (101).

5. A polysilicon cold hydrogenation reaction gas quenching system according to claim 4, characterized in that: The gas outlet (302) is provided with a pipeline connected to the STC feed port (103), and the pipeline is provided with a valve (304).

6. A polysilicon cold hydrogenation reaction gas quenching system according to claim 5, characterized in that: The slurry concentration tank (4) is provided with an exhaust gas outlet (401) at the top, a circulating cooling water pipe (402) is provided in the middle of the slurry concentration tank (4), and a slurry outlet (403) is provided at the bottom of the slurry concentration tank (4). The slurry outlet (403) is connected to a slurry treatment device (6); The exhaust gas outlet (401) is in communication with the slurry processing device (6), and the exhaust gas outlet (401) is also in communication with a hydrogen gas inlet pipe (7).

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