Low-temperature multiple-effect evaporation crystallization and filtration process

Abstract

The invention relates to a low-temperature multiple-effect evaporation crystallization and filtration process belonging to the technical field of chemical engineering separation and energy conversation and emission reduction. The process is characterized in that processes of low-temperature multiple-effect evaporation, crystallization and filtration, granulation and the like are coupled to form aset of complete waste liquid emission free process for concentrating and extracting solute. The process comprises two loops, wherein a three-effect evaporator, a cooler, a crystallization filter and a heat exchanger form a loop; a four-effect evaporator and a crystallization filter form the other loop; low-temperature heat source or waste heat is utilized in one-effect evaporation, and secondary steam generated by the former one-effect is utilized in other effect evaporation; and heat required by the heat exchanger in a three-effect evaporation circulating loop is supplied by heat released bytemperature reduction of a heat source flowing from a one-effect evaporator. The invention has the advantages of reducing investment cost by adopting the low-temperature heat source or waste heat andthe secondary steam as heat sources, lightening corrosion because the concentration of a solution is not overhigh by adopting a reflux mode, being not easy to block a pipe, reducing operation cost, and being capable of completely separating out the solute without emitting waste liquid.

Description

Technical field [0001] The invention belongs to the technical field of chemical separation and energy saving and emission reduction, and relates to a low-temperature multi-effect evaporation crystallization filtration coupled solute recovery process method, in particular to the multi-effect evaporation crystallization granulation of substances whose solubility does not change much with temperature, and waste heat utilization and Waste liquid emission reduction technology. Background technique [0002] The usual method of multi-effect evaporative crystallization is that the solution is concentrated by each effect evaporator in turn, and crystallization is performed at the last effect. In order to obtain more crystals, the concentration of the solution is often increased to a high level, a large amount of solvent needs to be evaporated and a large amount of heat source is consumed, resulting in high crystallization costs and insufficient crystallization; and high-concentration solu...

AI Technical Summary

Problems solved by technology

In order to obtain more crystals, the concentration of the solution is often raised to a high level, a large amount of solvent needs to be evaporated, and a large amount of heat source is consumed, resulting in high cost of crystallization and insufficient crystallization; and the corrosion of pipes and containers by high-concentration solutions is also very serious. It is easy to block the pipeline and the discharge port; at the same time, when the concentration is too high, the friction and collision between the solute particles will intensify, so that the resulting crystal particles will be smaller

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