China Nonferrous Metallurgy

The cooling circulating water system in the polysilicon production process is mainly used to cool the material, and is generally divided into an open circulating water system and a closed circulating water system. The main process components of the open circulating water system are open, and the source of supplementary water is generally industrial softened water. During the operation of circulating water, CO₂ content reduction, alkalinity increase, pH value increase, and turbidity increase will occur. It is necessary to monitor and control the indicators of cooling water and select suitable water treatment chemicals for dosing. The closed circulating water system is a closed system, and the requirements for circulating water are stricter. Compared with the open circulating water system, the components are more complicated, but the water quality control is easier. At present, the newer water quality control technologies include phosphorus-free descaling agent, electronic descaler and new anti-scale and anti-corrosion alloy materials. These new technologies can reduce subsequent cost input, and can reduce or even eliminate the cleaning of cooling towers and equipment. In new plant construction and technological transformation projects, the new technologies should be selected as far as possible.