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Novel process for recycling tail gas generated in polycrystalline silicon production

A new process, polysilicon technology, applied in the field of chemical engineering, can solve the problems of complex tail gas separation process, high equipment investment cost, high energy consumption, etc., and achieve the effects of stable content of each component of tail gas, reduced equipment investment, and reduced operating costs

Inactive Publication Date: 2013-02-13
天威四川硅业有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The method of this patent has the disadvantage of high energy consumption in actual operation, and the whole exhaust gas separation process is complicated, and the equipment investment cost is high

Method used

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  • Novel process for recycling tail gas generated in polycrystalline silicon production

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Embodiment 1

[0028] A new process for recovering the tail gas produced by polysilicon production, the components of the tail gas include H 2 , HCl, HSiCl 3 、SiCl 4 、H 2 SiCl 2 , it is characterized in that described new process comprises the following steps:

[0029] Cooling step: the tail gas output from the reduction furnace with a temperature of 500~600°C is cooled to 300°C for the first time, and then sent to the HCl converter;

[0030] Reaction steps: HCl and HSiCl in the HCl converter 3 、H 2 SiCl 2 The reaction completely generates the corresponding chlorosilane;

[0031] Gas-liquid separation step: After the tail gas from the HCl converter is cooled for the second time, the temperature of the tail gas drops to normal temperature, and then SiCl 4 Refrigerated liquid is sprayed, for H 2 Gas-liquid separation with chlorosilane;

[0032] h 2 Purification steps: the H 2 After being adsorbed and removed by the adsorption column, it is recovered and treated;

[0033] with H 2...

Embodiment 2

[0036] A new process for recovering the tail gas produced by polysilicon production, the components of the tail gas include H 2 , HCl, HSiCl 3 、SiCl4 、H 2 SiCl 2 , the new process comprises the following steps:

[0037] Cooling step: the tail gas output from the reduction furnace with a temperature of 500-600°C is cooled to 50°C for the first time through a heat exchanger and then sent to the fixed-bed reactor;

[0038] Reaction steps: In a fixed-bed reactor equipped with a polymer cross-linked resin catalyst, HCl and HSiCl 3 、H 2 SiCl 2 The reaction completely generates the corresponding chlorosilane; the reaction temperature is 50°C, the reaction pressure is 2.0MPa, and the HCl content in the tail gas output from the fixed bed reactor is less than 0.1%;

[0039] Gas-liquid separation step: the tail gas output from the fixed-bed reactor is cooled to normal temperature for the second time through a heat exchanger, and then SiCl 4 Refrigerated liquid is sprayed, for H 2...

Embodiment 3

[0044] A new process for recovering the tail gas produced by polysilicon production, the components of the tail gas include H 2 , HCl, HSiCl 3 、SiCl 4 、H 2 SiCl 2 , the new process comprises the following steps:

[0045] Cooling step: the tail gas output from the reduction furnace with a temperature of 500-600°C is cooled to 100°C for the first time through a heat exchanger and then sent to the fluidized bed reactor;

[0046] Reaction steps: In a fluidized bed reactor equipped with a copper molecular sieve catalyst, HCl and HSiCl 3 、H 2 SiCl 2 The reaction completely generates the corresponding chlorosilane; the reaction temperature is 100°C, the reaction pressure is 0.9 MPa, and the HCl content in the tail gas output from the fluidized bed reactor is less than 0.1%;

[0047] Gas-liquid separation step: the tail gas output from the fluidized bed reactor is cooled to normal temperature for the second time through a heat exchanger, and then SiCl 4 Refrigerated liquid is ...

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Abstract

The invention discloses a novel process for recycling tail gas generated in polycrystalline silicon production. The tail gas comprises H2, HCl, HSiCl3, SiCl4 and H2SiCl2; the novel process comprises the following steps of after cooling tail gas with temperature of 500-600 DEG C, which is output by a reducing furnace, for the first time, conveying the cooled tail gas to an HCl converter; completely reacting the tail gas with the HSiCl3 and the H2SiCl2 in the HCl converter so as to generate corresponding chlorosilane; after cooling the tail gas from the HCl converter for a second time, reducing the temperature of the tail gas to normal temperature; spraying SiCl4 refrigerating fluid to the tail gas; carrying out gas and liquid separation on the H2 and the chlorosilane; after adsorbing the H2 by an adsorbing column to remove impurities, recycling the H2; and after rectifying the chlorosilane liquid, recycling the separated HSiCl3. According to the invention, after the HCl is converted into the chlorosilane, the absorbing and desorbing process of the HCl is avoided, the separating process is simplified, raw materials are sufficiently recycled, consumption of steam and power is reduced, and the production cost of the polycrystalline silicon is reduced.

Description

technical field [0001] The invention belongs to the field of chemical engineering, in particular to a new process for recovering tail gas produced in polysilicon production. Background technique [0002] The main components of the reduction furnace exhaust gas in the polysilicon production process include H 2 , HCl, HSiCl 3 、SiCl 4 、H 2 SiCl 2 , this part of the material needs to be fully recycled. The method commonly used now is to cool the reduction tail gas, and carry out gas-liquid separation in further freezing, H 2 , HCl mixed gas is sprayed and absorbed by chlorosilane to absorb HCl, in order to fully absorb HCl, the mixed gas must be compressed, and the H that has been sprayed and absorbed 2 The content of HCl in the medium is about 0.1%, and it needs to go through the adsorption column for pressure swing adsorption to remove HCl; the chlorosilane dissolved with HCl needs to be analyzed by the desorption tower to separate chlorosilane and HCl. In this process...

Claims

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Application Information

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IPC IPC(8): C01B33/107C01B3/50
Inventor 李小港
Owner 天威四川硅业有限责任公司
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