Study on the Treatment of Scale Formation of Poly silicon High-salt Waste water
Aiming at the problem of serious scaling of heat exchanger in polysilicon high-salt wastewater evaporation system,the composition of scaling was analyzed.The results showed that the main component of scaling was calcium sulfate and a small part was calcium silicate.Process analysis showed that sulfate mainly came from the reverse osmosis concentrated water of the water reuse device,and calcium silicate came from the silica produced by the acid gas washing.The main reason was that the liquid flow rate in the evaporator heating system pipe was too slow and the evaporator did not set up automatic sewage discharge.Based on this,the following means were adopted in this study for process optimization and equipment optimization:the reverse osmosis effluent was added with the addition of hard equipment to separate and remove sulfate,the acid water was added with flocculant and the mechanical filtration was strengthened to remove silica,and the sulfate and silica in the incoming water were reduced to 100mg/L and 50mg/L,which would not cause scaling of the heater;the flow rate in the heater tube was increased from 1.5-1.7m/s to 2.5m/s,and the evaporator was added with automatic sewage discharge equipment.Starting from the water source and the improvement and optimization of the equipment,the scaling cycle of the heater was effectively prolonged,and the system could run smoothly for a long period.
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