A system and method for desulfurization waste water, salt separation, zero discharge and flue gas mercury removal

Abstract

The invention discloses a desulfurization waste water desalination zero discharge cooperative flue gas mercury removal system and method, including pretreatment and nanofiltration system, chlorine salt solution preheating and flue spraying system, sulfate solution multi-effect distillation system and freezing crystallization system. The nanofiltration device is used to realize the separation of desulfurization waste water salt, the chlorine salt solution is sprayed into the flue near the SCR after being preheated by the condenser to realize synergistic mercury removal; the sulfate solution is concentrated by multi-effect distillation and then frozen and crystallized, and the sulfate preheater recovers the heating steam The residual heat of condensate. The invention can realize zero discharge of desulfurization wastewater, and synergistically improve the efficiency of flue gas mercury removal, and has remarkable environmental protection benefits; the heat pump is used to increase the waste heat level of frozen crystallization to heat the chloride salt solution, and the condensed water is used to preheat the sulfate solution, effectively reducing the concentration energy consumption; The use of chlorine salt solution spraying in desulfurization wastewater to promote efficient demercury removal of flue gas has good economic benefits; the salt content of desulfurization wastewater is recovered through the freezing and crystallization system to realize resource utilization of desulfurization wastewater.

Description

technical field [0001] The invention belongs to the fields of zero discharge of desulfurization wastewater and flue gas mercury removal, and relates to a system and method for desulfurization wastewater with zero discharge of desulfurized salt and coordinated flue gas mercury removal. Background technique [0002] During the operation of coal-fired power plants, a large amount of desulfurization wastewater will be generated. The desulfurization wastewater has a high salt content, and direct discharge will cause environmental pollution. The current mainstream desulfurization wastewater treatment methods have high treatment costs, and it is difficult to separate the salts of different components, resulting in a waste of resources. The use of nanofiltration can effectively separate sulfate and chloride salts in desulfurization wastewater, and realize resource utilization of desulfurization wastewater. However, concentrating the crystalline chlorine salt solution requires a lar...

AI Technical Summary

Problems solved by technology

However, desulfurization wastewater contains more sulfate, which will inhibit the oxidation process of mercury in SCR, resulting in a decrease in mercury removal efficiency.

And the sulfate is sprayed into the flue, which cannot be recycled, resulting in waste of sulfate

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