Method for recycling heat energy from returned cooling water in production of polysilicon

Abstract

The invention relates to a method for recycling heat energy from returned cooling water in the production of polysilicon, belonging to the production field of polysilicon. In order to solve technical problem, the invention provides a method for recycling heat energy from returned cooling water in the production of polysilicon, which has high utilization rate of recycling heat energy from the returned cooling water. The method for recycling heat energy from returned cooling water in the production of polysilicon comprises the following steps: a, transfer of heat energy: the returned cooling water is adopted to concentrate lithium bromide dilute solution; b, release of heat energy: the concentrated lithium bromide solution is sprayed by water and the heat discharged therefrom is used to heat water to result in superheated water from 138 to 145 DEG C; and c, preparation of high temperature saturated steam: the superheated water is added to a flash device in order to instantaneously gasify the superheated water to the saturated steam from 128 to 132 DEG C. The method according to the invention has the advantages of: reducing the large use amount of cooling water for plate heat exchange, saving water resource, providing stable and excellent heat source for polysilicon, lowering the use amount of steam, economizing on energy and being favourable for environmental protection.

Description

technical field [0001] The invention relates to a method for recovering and utilizing heat energy of cooling return water in polysilicon production, and belongs to the field of polysilicon production. Background technique [0002] During the polysilicon production process, the silicon rods will generate a lot of heat, and the polysilicon reduction furnace needs to be cooled with cooling water. During the cooling process of the reduction furnace, a large amount of cooling return water will be generated (the temperature of the cooling return water is 105-115°C) and a large amount of residual heat. In the traditional polysilicon process, a large amount of cooling return water is mainly cooled with additional cooling water through the heat exchanger, which wastes a lot of heat energy. There are also a small number of polysilicon processes that use the generated cooling return water for flash evaporation to generate a small amount of low-pressure steam, and then reuse the low-pr...

AI Technical Summary

Problems solved by technology

In the traditional polysilicon process, a large amount of cooling return water is mainly cooled with additional cooling water through the heat exchanger, which wastes a lot of heat energy

There are also a small number of polysilicon processes that use the generated cooling return water for flash evaporation to generate a small amount of low-pressure steam, and then reuse the low-pressure steam to other places. Although this method uses part of the heat energy, it has higher requirements for the temperature of the cooling return water. And the steam pressure generated is not high, and the utilization rate of heat energy is also low