Low-temperature flash evaporation, concentration and crystallization integrated and zero-discharge process for treating desulfurization wastewater through concentrated liquid reflux

Abstract

The invention discloses a zero-discharge process for treating desulfurization wastewater by integrating low-temperature flash evaporation, concentration and crystallization and concentrated liquid reflux, which comprises a flue gas heat exchange system, a low-temperature multi-effect evaporation system, a condensate water system, a solid-liquid separation system, a filtrate reflux and electric heating system and a PH (potential of hydrogen) regulating system, the flue gas heat exchange system, the low-temperature multi-effect evaporation system, the solid-liquid separation system and the filtrate backflow and electric heating system are sequentially connected, the flue gas heat exchange system and the condensate water system are connected with the low-temperature multi-effect evaporation system, and the filtrate backflow and electric heating system is connected with the low-temperature multi-effect evaporation system. According to the invention, a low-temperature flash evaporation, concentration and crystallization integrated and concentrated liquid reflux process is adopted, and a traditional high-temperature flue gas drying process is cancelled, so that not only is the disadvantage of insufficient two-effect and three-effect evaporation capacity of a low-temperature multi-effect flash evaporation system overcome, but also the problems of high equipment investment cost and low energy consumption caused by high-temperature flue gas drying of concentrated water are solved. The operation and maintenance cost is high; and crystallized salt is disposed.

Description

technical field [0001] The invention relates to the technical field of zero-discharge processes, in particular to a zero-discharge process for the integration of low-temperature flash evaporation, concentration, crystallization, and concentrated liquid reflux treatment of desulfurization wastewater. Background technique [0002] With the gradual maturity of the low-temperature multi-effect flash evaporation + high-temperature drying and zero-discharge technology for the treatment of wet desulfurization wastewater from coal-fired power plants, the problem of inability to be directly discharged after neutralization of desulfurization wastewater from coal-fired power plants is solved. Multi-effect flash evaporation concentrates desulfurization wastewater, the concentrated water is only 1 / 3~1 / 10 of the wastewater, and then the concentrated liquid is dried by high-temperature flue gas, and the dried crystalline salt is collected separately or together with fly ash. use. [0003]...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the low-temperature multi-effect flash evaporation technology in the prior art is insufficient in the second-effect and third-effect evaporation, and also to solve the above-mentioned defects in the high-temperature flue gas drying system, and proposes a low-temperature flash evaporation Zero discharge process of concentration and crystallization integration and concentrated liquid reflux treatment of desulfurization wastewater

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