Method and device for salt separation and crystallization of high-salinity wastewater in coal chemical industry

Abstract

The invention relates to a method and a device for salt separation and crystallization of high-salinity wastewater in the coal chemical industry. The device comprises a first MVR (mechanical vapor recompression) forced evaporation unit, a cyclone separation filtering unit, a nanofiltration membrane group unit and a second MVR forced evaporation unit. The first MVR forced evaporation unit is used for evaporation of the high-salinity wastewater in the coal chemical industry to obtain sodium sulfate crystalline salt and first crystallization mother liquor; the cyclone separation filtering unit is used for removing tiny solid crystalline salt particles from the first crystallization mother liquor; the nanofiltration membrane group unit is used for removing divalent sulfate ions from the first crystallization mother liquor; the second MVR forced evaporation unit is used for evaporation and concentration of sodium chloride containing waste water to obtain sodium chloride crystalline salt and second crystallization mother liquor; the second MVR forced evaporation unit sends the second crystallization mother liquor into the nanofiltration membrane group unit to realize cyclic separation. The method and the device for salt separation and crystallization of the high-salinity wastewater in the coal chemical industry have advantages that low energy consumption, low cost and freeness of secondary pollution in treatment of the high-salinity wastewater are realized, resource recycling is realized as well, purity in salt separation and crystallization is greatly improved, and zero emission of wastewater is guaranteed.

Description

technical field [0001] The invention relates to the technical field of environmental protection, in particular to a device and method for salt separation and crystallization of high-salt wastewater from coal chemical industry. Background technique [0002] my country is a large coal-producing country and a large coal chemical industry. A large number of coal chemical enterprises will produce a large amount of high-salt wastewater discharge in the production process. In the field of high-concentration saline wastewater treatment, traditional multiple-effect evaporation methods are often used for treatment. The secondary steam of traditional multi-effect evaporation cannot be fully utilized, and the energy-saving effect is not as good as that of MVR (mechanical vapor recompression). Multi-effect evaporation also requires the use of circulating cooling water, which increases the cost of water and electricity consumption for cooling towers. In addition, traditional multi-effe...

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Problems solved by technology

[0004] The present invention provides a device and method for salt separation and crystallization of high-salt wastewater in the coal chemical industry, which solves or partially solves the problems of high energy consumption, high operating cost, and large equipment footprint in the prior art. Avoid the technical problems of crystallization and fouling inside the evaporator, realize low energy consumption, low cost, and no secondary pollution to treat high-salt wastewater and realize resource recycling, greatly improve the purity of crystallization and salt separation, and ensure zero discharge of wastewater technical effect

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