Pretreatment method for high-salinity desulfurized wastewater of coal-fired power plant and system

Abstract

The invention relates to the field of purification of high-salinity desulfurized wastewater of coal-fired power plants and discloses a pretreatment method for the high-salinity desulfurized wastewaterof a coal-fired power plant and a system. The method comprises the steps: (1) subjecting the desulfurized wastewater to pH adjusting, so as to obtain raw liquor; (2) adding a microbicide into the rawliquor, and carrying out filtering treatment, so as to obtain filtering produced water; (3) adding a scale inhibitor and a scale inhibitor deactivator into the filtering produced water, and carryingout ion separation, so as to obtain high-concentration brine and pretreatment produced water; (4) adding lime into the high-concentration brine, carrying out a primary reaction, and subjecting an obtained primary reaction product to primary solid-liquid separation, so as to obtain primary clear water and primary sludge; (5) subjecting the primary clear water to acidity adjusting, so as to obtain acidity adjusted produced water; and (6) adding sodium sulfate into the acidity adjusted produced water, and carrying out a secondary reaction and normal-temperature calcium sulfate separation by crystallization sequentially, thereby obtaining secondary clear water and secondary sludge, wherein the secondary clear water returns to the step (2) for filtering treatment. By the method and the system,the pretreatment cost of the desulfurized wastewater of the coal-fired power plant can be effectively reduced.

Description

technical field [0001] The invention relates to the field of purification of high-salt desulfurization wastewater in coal-fired power plants, in particular to a pretreatment method and system for high-salt desulfurization wastewater in coal-fired power plants. Background technique [0002] Most power plants and coal chemical plants in my country use limestone wet desulfurization technology to remove SO from flue gas. 2 , the resulting desulfurization wastewater has become one of the most difficult wastewater for coal-fired power plants due to its complex composition and many types of pollutants. At present, the chemical precipitation method (commonly known as triple box precipitation) is mainly used in China to treat desulfurization wastewater. The treated water has a high salt content, and it is easy to cause secondary pollution after direct discharge. At the same time, due to the small amount of desulfurization wastewater and high salt content, the process system for furt...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a pretreatment method and system for high-salt desulfurization wastewater in coal-fired power plants in order to overcome the problems of impure removal products and high process operating costs in the prior art. The application of the method and system can effectively Highly separate monovalent ions and divalent ions in desulfurization wastewater, and can recover calcium sulfate with higher purity, and can reduce the operating cost of purification and pretreatment of high-salt desulfurization wastewater in coal-fired power plants

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