Sodium sulfide MVR plate-type evaporation process

Abstract

The invention discloses a sodium sulfide MVR plate-type evaporation process which comprises the following steps: S1, feeding sodium sulfide feed liquid with the concentration of 65g / l and the temperature of 40 DEG C in a feeding balance tank into an original second-effect preheater, then feeding into an original third-effect preheater or an original fourth-effect preheater, finally feeding into anoriginal first-effect preheater, and preheating to 105 DEG C; S2, injecting the sodium sulfide feed liquid preheated to 105 DEG C in the step S1 into a chamber A of a plate-type evaporator, then feeding the sodium sulfide feed liquid into a chamber B, enabling a concentrated solution to take effect, feeding the sodium sulfide feed liquid with the concentration of 200g / l and the temperature of 98DEG C into a concentrated solution tank, buffering, then feeding the sodium sulfide feed liquid into the next section for concentration, and simultaneously generating secondary steam; switching an integrated two-chamber belt, enabling a thinner to enter the chamber A to be evaporated and then enter the chamber B to be evaporated and then to be discharged in the first eight hours, enabling the thinner to enter the chamber B to be evaporated and then enter the chamber A to be evaporated and then to be discharged in the later eight hours, so that the dissolving and descaling efficiency is higher,the system has a self-cleaning function, the operation period of the system is further prolonged, and the operation cost of enterprises is reduced.

Description

technical field [0001] The invention belongs to the technical field of sodium sulfide evaporation process, in particular to a sodium sulfide MVR plate evaporation process. Background technique [0002] The production methods of sodium sulfide mainly include carbon reduction method, hydrogen sulfide method, barium sulfide method and gas reduction method. The present invention mainly aims at the process of producing precipitated barium sulfate by-product sodium sulfide (alkali) by barium sulfide method. Add barium sulfate to sodium sulfate solution to generate sodium sulfide and precipitate barium sulfate. The mother liquor rich in sodium sulfide is separated by centrifugation and concentrated by evaporation. The cost is low. The sodium sulfide evaporation process mainly includes large pot open flame evaporation, rotary thin film evaporator, vacuum continuous evaporator, plate evaporator, polytetrafluoroethylene heat exchange device etc. [0003] The barium sulfide method b...

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Problems solved by technology

[0003] The barium sulfide method by-product sodium sulfide (alkali) due to excessive addition of barium sulfide, and alkaline pH (exposure conditions will absorb carbon dioxide in the air), in the process of heating up and concentrating the material, barium ions will be mixed with residual sulfate Ions and absorbed carbonate ions react to form insoluble barium sulfate and barium carbonate, which are precipitated and adhere to the heat transfer surface, reducing heat transfer efficiency and system productivity. The system needs to be cleaned after continuous operation for less than two weeks. , increasing the operating cost of the enterprise;

[0004] Most enterprises now adopt the four-effect vacuum continuous evaporation process, which consumes a relatively large amount of steam. Since steam production has gradually changed from burning coal to burning natural gas, the cost of steam has increased sharply, and the cost of steam has become a major part of the operating cost of the evaporation system. The main part has greatly increased the burden on the enterprise, so we propose a sodium sulfide MVR plate evaporation process

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