Multi-stage absorption, regeneration and purification method of polysilicon tail gas

Abstract

A method for purifying polysilicon tail gas by multilevel adsorption and multilevel regeneration belongs to the technical field of adsorption and separation engineering, comprising the adsorption process of the polysilicon tail gas in a tower, the regenerative process for the tower by utilizing purified hydrogen as well as the adsorption and preparation process of cooling and increasing the pressure carried out on the tower which completes regeneration; wherein, the adsorption process is carried out by the serial adsorption of two towers, and the feeding time of the latter tower lags comparedwith the former tower; the regenerative process is cascade heating regeneration of a plurality of towers, and the heating part of each regeneration tower is completed by being divided into multiple levels. The method has the advantages that the utilization rate of adsorbent is improved and the adsorption period is shortened. The cascade regeneration mode of the purified hydrogen without power cycle causes the hydrogen used for regeneration to be utilized fully and effectively, thus greatly reducing the use amount of resurgent gases and saving the investment of power equipment and power consumption at the same time.

Description

technical field [0001] The invention relates to a polysilicon tail gas purification and recovery process. It belongs to the technical field of adsorption separation engineering. Background technique [0002] Reduction of SiHCL with hydrogen 3 In the process of generating polysilicon, a large amount of hydrogen-rich tail gas containing impurities such as hydrogen chloride and chlorosilane will be produced. In order to improve economic benefits and protect the environment, the polysilicon tail gas must be cleaned of impurities and purified to recover hydrogen, hydrogen chloride and chlorosilane and other process gases. , so that it can be returned to the polysilicon synthesis system for reuse. The composition of polysilicon tail gas is complex, the purification requirements are high, and the purification is difficult. It has always been an important and technically difficult link in the polysilicon production process. [0003] "Nonferrous Smelting" Volume 29, Issue 6 "Purif...

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Problems solved by technology

Since only the traditional adsorption regeneration method is used to purify the tail gas, the disadvantages of this technology are: low hydrogen yield, low purity of purified gas, low safety performance, complex structure of the adsorption tower, etc.

[0005] 1) The adsorption period of a single adsorption tower is long, generally 6-8 hours, which results in a large volume of the adsorption tower and a large amount of adsorbent;

[0006] 2) Adopt the hydrogen cycle heating-cooling method, and at the same time design the auxiliary hydrogen direct purge regeneration, and the regeneration method of auxiliary heating such as adsorption tower coil heating is more complicated, and the hydrogen cycle needs to be boosted by the compressor, resulting in high energy consumption increase and the difficulty of equipment processing

[0007] 3) The adsorption preparation method completed by two hydrogen channels is complicated and the energy consumption is high

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