Trichlorosilane distillation technology including tail gas recovering and distilling treatment

Abstract

The invention relates to a distillation technology of trichlorosilane, in particular to a trichlorosilane distillationn technology including tail gas recovering and distilling treatment. The technology comprises the steps of making feeding liquid pass through two sieve plate distillation columns in sequence for being subjected to distillation into a finished product, combining tail gas, conducting tail gas recovering and distilling operation through a tail gas preprocessing device and two tail gas sieve plate distillation columns in sequence, and finally obtaining a high-purity trichlorosilane product and a silicon tetrachloride crude product. By means of the technology, the trace impurity removing capacity which original technology procedures can not achieve can be improved, great improvement is achieved on improving the product purity, the separation effect is better, and the requirements of polycrystalline silicon manufacturers can be satisfied.

Description

technical field [0001] The invention relates to a rectification process of trichlorosilane, in particular to a rectification process of trichlorosilane including tail gas recovery rectification treatment. Background technique [0002] Disadvantages of the traditional trichlorosilane crude product distillation process: the traditional trichlorosilane crude product rectification process only removes silicon tetrachloride and high boiling point compounds, as long as the product purity trichlorosilane mass percentage reaches 99.0%. The ability to remove trace impurities such as boron and carbon is poor. Disadvantages of the traditional trichlorosilane crude product distillation process: the traditional trichlorosilane crude product rectification process only removes silicon tetrachloride and high boiling point compounds, as long as the product purity trichlorosilane mass percentage reaches 99.0%. The ability to remove trace impurities such as boron and carbon is poor. [0003]...

AI Technical Summary

Problems solved by technology

[0002] Disadvantages of the traditional trichlorosilane crude product distillation process: the traditional trichlorosilane crude product rectification process only removes silicon tetrachloride and high boiling point compounds, as long as the product purity trichlorosilane mass percentage reaches 99.0%. Poor ability to remove trace impurities such as boron and carbon

Disadvantages of the traditional trichlorosilane crude product distillation process: the traditional trichlorosilane crude product rectification process only removes silicon tetrachloride and high boiling point compounds, as long as the product purity trichlorosilane mass percentage reaches 99.0%. Poor ability to remove trace impurities such as boron and carbon

This will increase the consumption of lye, waste the effective substances in the tail gas and pollute the environment

Although some existing tail gas treatment methods improve the improved Siemens method and comprehensively utilize and recycle the synthetic tail gas, the recovery device is either too complicated and the recovery process is long, which leads to an increase in the cost of tail gas recovery, or the recovery device is too simple and the recovery The efficiency is too low, the benefits are not obvious, and the promotion effect is not good

[0005] However, the process parameters and route design in the prior art can only remove high boiling point compounds well, and have poor removal ability for trace impurities such as boron and carbon.

The process parameters and route design in the above literature can only remove high boiling point compounds well, but have poor removal ability for trace impurities such as boron and carbon.

[0006] For example, the more popular process for producing high-purity trichlorosilane and silicon tetrachloride requires six rectification towers, which requires large investment, high cost, and high energy consumption. Therefore, it often saves costs and reduces pollution in tail gas treatment. environment, the residual trichlorosilane and silicon tetrachloride in the tail gas cannot be recovered, resulting in waste

[0007] To sum up, the rectification products produced by the traditional trichlorosilane crude product distillation process are increasingly unable to meet the needs of the market, and it is very necessary to modify the rectification process; at the same time, for enterprises, if they want to continue to survive and develop, energy saving Consumption reduction is the only way for enterprises