Desulfurization wastewater zero discharge system utilizing flue gas waste heat of power plant

Abstract

The invention provides a desulfurization wastewater zero-discharge system utilizing flue gas waste heat of a power plant. The desulfurization wastewater zero-discharge system comprises a wastewater regulating tank, a high-density sedimentation tank, a low-temperature multistage flash evaporation unit and a bypass flue evaporation unit which are connected in sequence, and the wastewater regulatingtank is communicated with a desulfurization wastewater discharge pipeline of a flue gas wet desulfurization absorption tower. According to the invention, the pH value of desulfurization wastewater isincreased by adding a medicament into the wastewater regulating tank; the high-density sedimentation tank realizes efficient pretreating of the desulfurization wastewater through flocculation, sedimentation and clarification; the low-temperature multistage flash evaporation unit can realize multistage flash evaporation concentration reduction and water recovery of the wastewater by utilizing the flue gas waste heat; the bypass flue evaporation unit can utilize flue gas waste heat to achieve waste water evaporation and crystallization treating. Compared with the prior art, the desulfurization wastewater is pretreated by adopting the high-density sedimentation tank, so that the occupied area is reduced; the flue gas low-temperature multistage flash evaporation unit and the bypass flue evaporation unit both utilize heat carried by flue gas, an external heat source is not needed, and the operation cost is reduced.

Description

technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to a zero-discharge system for desulfurization wastewater utilizing waste heat from flue gas from a power plant. Background technique [0002] At present, coal-fired power plants generally use limestone / gypsum wet desulfurization technology to remove SO from flue gas. 2 , The desulfurization wastewater generated is complex in quality, with high suspended solids content, high salt content, high hardness, high chloride ion content, and excessive COD, fluoride, and heavy metal content. At present, the standard discharge of desulfurization wastewater is treated by chemical precipitation, mainly through oxidation, neutralization, precipitation, flocculation and other processes to remove pollutants such as heavy metals and suspended solids in desulfurization wastewater, but the salt content in the discharged water is still High, easy to corrode and scale, making the wastewat...

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Problems solved by technology

[0002] At present, coal-fired power plants generally use limestone / gypsum wet desulfurization technology to remove SO from flue gas. 2 , the water quality of the desulfurization wastewater produced is complex, with the characteristics of high suspended solids content, high salt content, high hardness, high chloride ion content, and excessive COD, fluoride and heavy metal content

At present, the up-to-standard discharge of desulfurization wastewater is treated by chemical precipitation, mainly through oxidation, neutralization, precipitation, flocculation and other processes to remove pollutants such as heavy metals and suspended solids in desulfurization wastewater, but the salt content in the discharged water is still Very high, easy to corrode and scale, making the wastewater reuse rate very low

[0003] At present, the pretreatment unit of the desulfurization wastewater zero discharge process commonly used is equipped with wastewater buffer tanks, flocculation reaction tanks, sedimentation tanks, clarification tanks and other structures, which occupy a large area and require laying more pipelines, which is not easy to maintain and manage.

The thermal concentration technology commonly used for concentration reduction has high energy consumption, and the membrane method for weight reduction technology is prone to fouling, resulting in an increase in operating costs

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