Alumina mother liquor MVR circulation evaporation device and process

Abstract

The present invention provides an alumina mother liquor MVR circulation evaporation device and process, technical features are as follows: seed precipitation mother liquor first enters a preheater for heat exchange with vapor condensate water, then enters an evaporator for evaporation, and then enters a vapor-liquid separator; vapor flows out from the top of the vapor-liquid separator, then enters a vapor compression machine to form secondary vapor by temperatures and pressure increase under the effect of the vapor compression machine, and re-enters the evaporator to form a vapor circulation loop; at the same time, the separated mother liquor flows out from the bottom of the vapor-liquid separator, one part of the separated mother liquor flows again back to the evaporator to form a mother liquor circulation loop, and the other part of the separated mother liquor is discharged from a discharge port. The alumina mother liquor MVR circulation evaporation device can be used for alumina mother liquor circulation evaporation, and improves the quality of alumina evaporation mother liquor; the secondary vapor and the condensate water both can be recycled, the evaporation energy consumption is effectively reduced, and the producing capacity of the evaporation process can be improved.

Description

technical field [0001] The invention relates to an evaporation device for decomposing mother liquor in the alumina production process and an evaporation process thereof, belonging to the technical field of evaporation and concentration. Background technique [0002] Evaporation of mother liquor is one of the important processes in alumina production. It is responsible for maintaining the liquid volume balance in the circulation system, providing a suitable concentration of lye for the preparation of raw slurry or dissolution of bauxite, and eliminating the carbon and alkali accumulated in the production process. The condensed water produced during the evaporation process can be supplied to the thermal boiler. The mother liquor evaporation process is a major energy consumer in alumina production. Steam consumption accounts for more than 40% of the entire alumina production steam consumption, and evaporation costs account for about 10% of the entire alumina production. Therefo...

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Problems solved by technology

[0004] At present, most domestic alumina production enterprises use five-effect and six-effect cross-flow evaporation systems to process alumina mother liquor. This type of system has the following disadvantages: long process flow, cumbersome control points, and high energy consumption; a large amount of heat is generated by The secondary steam of the final effect is brought out and discharged into the environment through the cooling system; fossil fuels are the only energy source, and the carbon emissions are large, which is easy to cause environmental pollution; the energy utilization efficiency of raw steam as a heat source is low

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