Coal water slurry gasification wastewater salt separation and crystallization zero discharge treatment system and coal water slurry gasification wastewater salt separation and crystallization zero discharge treatment method

Abstract

The invention discloses a coal water slurry gasification wastewater salt separation and crystallization zero discharge treatment system and a coal water slurry gasification wastewater salt separationand crystallization zero discharge treatment method, wherein the system comprises a pretreatment system, a salt separation system, a mirabilite crystallization system and a salt crystallization system. The method comprises: S1, pretreatment, S2, salt separation, S3, output of sodium chloride, S4, output of sodium sulfate, and S5, treatment of mother liquor. According to the present invention, on the basis of meeting of the operation requirements of the system, the repeated arrangement of the chemical softening, the filtering and the membrane system in the treatment of the coal water slurry gasification wastewater by the traditional high salt content wastewater treatment system is simplified so as to reduce the investment and construction cost of the system and reduce the energy consumptionof the pretreatment system; the salt separation system is optimized, wherein the reverse osmosis production water is mixed with the first nano-filtration concentrated water according to a certain ratio, and the obtained mixture is subjected to second-stage nano-filtration, such that the operating pressure of the second-stage nano-filtration is reduced, the recovery rate of the second-stage nano-filtration is improved, and the service life of the equipment is prolonged; and the crystallization system is optimized, and the recovery rates and the purities of sodium chloride and sodium sulfate are improved.

Description

Technical field:

[0001] The invention relates to the field of coal gasification, in particular to a zero-discharge treatment system and method for coal-water slurry gasification waste water, salt separation and crystallization. Background technique:

[0002] Coal-water slurry gasification technology is a coal gasification technology that uses coal-water slurry as the raw material for coal gasification. Due to the high reaction temperature and pressure of coal-water slurry gasification technology, the effective components in the coal-water slurry can be recovered in the gasifier. Complete conversion is achieved, and the organic matter, pollutants and solid impurities carried in the coal-water slurry and produced during the gasification process enter into the coal-water slurry gasification wastewater, and the coal-water slurry gasification wastewater can be recycled after being reused. The highest recovery rate is 80%; while the other 20% coal-water slurry gasification wastewa...

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