Local forced circulation desalting method for multi-effect evaporating system

Abstract

The invention relates to a local forced circulation desalting method for a multi-effect evaporating system, belonging to the field of chemical separation engineering. The local forced circulation desalting method comprises the following steps: each effect evaporator maintains a boiling point temperature of a material liquid and evaporates continuously under an operating pressure, and a dissolved salt reaches a saturation state and is separated out; solid substances such as separated salt enter a local forced circulation pipeline under the effects of sedimentation and material liquid circulation of heat exchange and gas-liquid separation for the evaporating system, and part of salt-containing material liquid is extracted from the local forced circulation pipeline under the effect of a circulation pump; solid and liquid phases with different densities are separated in a cyclone hydraulic separator and are discharged to a salt slurry collecting tank under the effect of centrifugal force;and the liquid phase extracted from the cyclone hydraulic separator returns to the entrance of the local forced circulation pipeline again so as to complete the local external circulation of primary material liquid. The method can transfer the solid salt separated from the material liquid out of the multi-effect evaporating system in time, and can be used for the heterogeneous system separation procedure of the multi-effect evaporating system with separated solids.

Description

technical field [0001] The invention relates to a local forced circulation desalination process for a multi-effect evaporation system, in particular to a liquid-solid heterogeneous separation process including the use of a circulating pump, a local forced circulation pipeline, and a hydrocyclone, belonging to the chemical industry Separation of engineering domains. The process method of the invention can be used in the continuous separation process of the heterogeneous phase system in the multi-effect evaporation system. Background technique [0002] Evaporation is a commonly used unit process in chemical production and environmental protection treatment, and is used for material liquid concentration and light component recovery. In the application process, in order to make full use of heat energy, the evaporation process is often designed in the form of multi-effect evaporation. However, since the specific application system often contains components such as salts, as the...

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Problems solved by technology

In these methods, issues such as how to selectively and continuously remove solids from the evaporation system, keep the solid salt content of the feed liquid in the evaporator low, and avoid sediment blocking the pipeline are not covered.

[0005] In addition, in the reported method, after multi-effect evaporation, the solid salt-containing feed liquid reaching a certain concentration is discharged out of the system as a whole, and after operations such as crystallization and salt separation and solid-liquid separation, the clear liquid is combined with the initial raw material liquid Returning to the multi-effect evaporation system, this increases the salt concentration in the mixed feed liquid, which in turn increases the corresponding boiling point of the feed liquid, thereby reducing the average temperature difference of the heat exchanger, affecting the heat exchange efficiency of the heat exchanger, and also making the Salt precipitation time is advanced

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