Continuous evaporative crystallization method

Abstract

The invention relates to a continuous evaporative crystallization method for saving energy by virtue of mechanical steam recompression. The method comprises the following steps: (a), adding raw materials into a tank, and stirring to obtain a solution; (b), pumping the solution to a first heater, and heating to a bubble point temperature by virtue of the first heater; (c), feeding the hot solution in the step (b) into a climbing film evaporator for heating, so that the climbing film evaporator generates lots of secondary steam, spraying the solution into a gas-liquid separator at the speed of 25-50m / s by virtue of the secondary steam; (d), separating by virtue of the gas-liquid separator, discharging one part of the concentrated solution by virtue of the gas-liquid separator, performing forced-circulation evaporation, feeding the solution back to the gas-liquid separator after forced-circulation evaporation, and discharging and crystallizing the other part of the solution; and (e), recompressing the steam discharged by the gas-liquid separator into superheated steam by virtue of a compressor, feeding the steam serving as a heating source of the climbing film evaporator back to the climbing film evaporator, so that the hot solution in the step (c) can be heated by the superheated steam. The continuous evaporative crystallization method is low in cost, multi-level recovery of the energy and raw materials is realized, and the energy consumption is low.

Description

technical field [0001] The present invention relates to a continuous evaporative crystallization method that saves energy by mechanical vapor recompression. Background technique [0002] Mechanical Vapor Recompression (Mechanical Vapor Recompression) technology is a high-efficiency energy-saving and environmental protection technology. This technology mainly uses a mechanical device to transfer the heat energy of a low-temperature object to a higher-temperature object. The specific process is to compress the secondary steam generated during the evaporation process through a mechanical steam compressor (the compression medium is generally water vapor), so that the temperature and pressure increase, and the enthalpy value increases, so that the compressed steam can be directly used as The heating source of the system at this level. The compressed steam enters the heating outer tube to heat the solution, the secondary steam releases its latent heat and condenses into condensed...

AI Technical Summary

Problems solved by technology

[0003] Although many continuous evaporation crystallization devices and methods using mechanical vapor recompression technology are disclosed in the prior art, and many mechanical vapor recompression continuous evaporation crystallization systems generally only have a single-stage steam compressor to supply heat to the evaporator, and in the crystallizer part , the material is still not supplied with a large amount of heat, resulting in poor crystallization effect of the existing mechanical vapor recompression continuous evaporation crystallization system, such as problems such as fine crystal particle size

Of course, some manufacturers will add steam pipes to supplement the heating of the crystallization part, but this greatly increases the complexity of the MVR system and relies on steam boilers, making the MVR system lose its original significant advantage - get rid of the dependence on steam boilers

In view of these problems, the publication number is CN103203116A Chinese Invention Patent Application Publication Specification discloses a mechanical vapor recompression continuous evaporation crystallization system and method to solve the above problems, the mechanical vapor recompression continuous evaporation crystallization system uses two mechanical vapor compression machine, and the two compressors supply heat to the evaporator and the crystallizer respectively, and also recover the sensible heat of the condensed water for preheating, but the continuous evaporation and crystallization system uses two mechanical steam compressors, and two mechanical steam compressors are purchased The equipment cost of the compressor is very high, and there is no reasonable structure to preheat the material to the bubble point temperature, so the energy consumption of starting two compressors is also high, and the structure is complicated, resulting in unsatisfactory energy saving effect

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