A desulfurization wastewater treatment system

Abstract

The invention relates to a desulfurization wastewater treatment system. The system is used for treating desulfurization wastewater from a desulfurization system, and comprises a pretreatment system, a membrane treatment system and an evaporative crystallization system which are arranged sequentially, wherein the pretreatment system is used for pre-treating desulfurization wastewater, the membrane treatment system is used for deeply treating the pretreated desulfurization wastewater, and the evaporative crystallization system is used for vaporizing and crystallizing the concentrate in the membrane treatment system to obtain crystalline salt. According to the desulfurization wastewater treatment system, the pretreated desulfurization wastewater is treated by a nano-filtration treatment system to separate monovalent and divalent ions, so that quality-divided recycling of desulfurization wastewater can be realized, and the reuse rate of water can be improved; and the water output from a reverse osmosis system is used to wash the nano-filtration treatment system, so that the dosage of a softening agent in a softening and clarifying system and the dosage of a scale inhibitor in the nano-filtration treatment system can be respectively reduced.

Description

technical field [0001] The invention belongs to the field of industrial sewage treatment, in particular to a desulfurization wastewater treatment system. Background technique [0002] Coal-fired power plants occupy a dominant position in my country's power supply enterprises. In order to avoid air pollution, desulfurization of flue gas is required. At present, the limestone-gypsum method is mainly used in flue gas desulfurization projects of coal-fired power plants at home and abroad, and the system will generate a certain amount of desulfurization wastewater. Desulfurization wastewater contains a large amount of suspended solids, sulfate, chloride, hardness, high salt content, and a certain amount of heavy metal ions, which is extremely harmful to the environment and must be strictly treated. The traditional "three-box" process neutralizes, flocculates, and settles desulfurization wastewater to remove suspended solids and heavy metals in the wastewater. The treatment effec...

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Problems solved by technology

Patent 201310555063.9 uses a combination of seawater membrane and high-pressure resistant membrane, and reacts and crystallizes the salty brine from the high-pressure membrane with the fly ash in the ash field. The operating pressure of the membrane in this process is very high, and the requirements for pretreatment are high. Chemicals and energy consumption Larger, and concentrated brine is wasted, and the water reuse rate is low

Patent application 201510275955.2 discloses a zero-discharge process for desulfurization wastewater, which adopts two-stage softening followed by nanofiltration and reverse osmosis separation, and uses ion exchange, freeze crystallization and evaporation processes to achieve salt separation, but this process also has high operating pressure and dosage Large volume of concentrated water, high energy consumption and complicated process

Patent application 201410240730.9 discloses a desulfurization wastewater recycling and zero discharge system. The wastewater is pretreated by multi-stage filtration and separated by two-stage nanofiltration. The concentrated nanofiltration water is returned to the desulfurization tower. Evaporation and crystallization after concentration, but the nanofiltration stage of this process has a high risk of scaling, a large amount of antiscalant dosing, high operating pressure, and the quality of concentrated water is difficult to guarantee, and subsequent softening treatment is also required, and the process line is long and complicated

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