Desulfurization wastewater salt-separation zero-emission synergistic flue gas mercury removal system and method

Abstract

The invention discloses a desulfurization wastewater salt-separation zero-emission synergistic flue gas mercury removal system and method. The system comprises a pretreatment and nanofiltration system, a chlorine salt solution preheating and flue spraying system, a sulfate solution multi-effect distillation system and a freezing crystallization system. A nanofiltration device is adopted to realizesalt separation of desulfurization wastewater, and a chlorine salt solution is preheated by a condenser and then sprayed into a flue near an SCR to realize synergistic mercury removal; a sulfate solution is frozen and crystallized after multiple-effect distillation and concentration, and a sulfate preheater recovers waste heat of heating steam condensate water. Zero emission of desulfurization wastewater can be realized, the flue gas mercury removal efficiency is synergistically improved and the environmental protection benefit is remarkable; the heat pump is adopted to improve the grade of freezing crystallization waste heat to heat the chlorine salt solution, the condensate water is utilized to preheat the sulfate solution, and concentration energy consumption is effectively reduced; the chlorine salt solution in the desulfurization wastewater is adopted for spraying to promote efficient mercury removal of the flue gas, and good economic benefits are achieved; and desulfurization wastewater salt is recycled through the freezing crystallization system, and desulfurization wastewater resource utilization is achieved.

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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