Method for washing rectifying column reboiler

Abstract

The invention relates to a method for washing a rectifying column reboiler. The method includes the steps of (1), when the reboiler is blocked and vapor-liquid load of a rectifying column is decreased to the minimum, enabling the rectifying column to stop running; (2), discharging a mixture containing trichlorosilane, silicon tetrachloride and metal chlorides in the rectifying column to a raw material storage tank; (3), when liquid level of a column bottom decreases to 5%, stopping discharge and supplementing fresh liquid-phase silicon tetrachloride; when the liquid level of the column bottom rises to 80%, stopping supplementing the fresh liquid-phase silicon tetrachloride and starting to heat to increase temperature while turning on a condenser so as to enable the rectifying column to be in total-reflux operation; (4), when impurity content of the silicon tetrachloride in the column bottom decreases to 0.02%, stopping heating; (5), when temperature of the column bottom decreases to 80 DEG C, discharging the silicon tetrachloride and the metal chlorides dissolved in the silicon tetrachloride and pressurizing by nitrogen; when pressure of the rectifying column reaches 0.3 MPa, relieving pressure and replacing all the silicon tetrachloride by means of purging so as to start up the rectifying column normally. The method for washing the rectifying column reboiler has the advantages of high efficiency, rapidity and environmental protection.

Description

Technical field [0001] The invention relates to the technical field of polysilicon production, in particular to a method for cleaning the reboiler of a rectification tower. Background technique [0002] Ninety percent of polysilicon production uses the modified Siemens method. The entire industry is facing the dual pressure of cost reduction and environmental protection. How to achieve cost reduction and environmental pollution has become the foundation of enterprise development. Trichlorosilane is the main raw material for polysilicon production, and the method of distillation and purification to obtain high-purity trichlorosilane is the key to polysilicon production. The purity of trichlorosilane directly affects the quality of polysilicon products. Since silicon powder is used in the hydrogenation raw materials of trichlorosilane, the metal chloride impurities in silicon powder are relatively high, and in the chlorosilane production process, due to the relatively high temperat...

AI Technical Summary

Problems solved by technology

In this patent, the devices are relatively complicated, and a tower kettle material circulation pump is added. Due to the pressurization of the system, the operating pressure of the system is high. Due to the characteristics of flammability and explosion of chlorosilane, the hidden danger and operating cost of the complete and stable operation of the system are increased.

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