MVR Forced Circulation Evaporator

This evaporator is a combination of MVR evaporator and forced circulation evaporation process. The use of MVR and forced circulation process can provide sufficient circulation speed for crystal growth, effectively reduce solution supersaturation, avoid solution explosion nucleation, effectively increase the flow rate between heating chamber tubes, increase the heat transfer coefficient and avoid material blocking. The effect of reducing operating costs is considerable, and considerable economic benefits are increased.

The forced circulation evaporator consists of each effect heating chamber, evaporation crystallization chamber, condenser, circulation pump, vacuum and drainage system, gas-liquid separation chamber, secondary steam flash tank, salt separator, operating platform, detection instrument and electrical instrument control cabinet and valve and pipeline system.

Working principle:

The material is heated by steam outside the heat exchange tube in the heat exchanger tube to increase the temperature. Under the action of the circulation pump, the material rises to the separator, and the material evaporates in the separator due to the decrease in static pressure of the material.

Evaporation produces secondary steam overflowing from the material, the material is concentrated to produce supersaturation and crystallization, and the supersaturated material enters the forced circulation pump and enters the heat exchanger under the action of the circulation pump. The material is continuously evaporated and concentrated or concentrated and crystallized in this cycle. The crystal slurry is discharged from the circulation pipeline by the discharge pump. The secondary steam in the evaporator separator is purified by the separation and defoaming device on the upper part of the evaporator separator and then transported to the compressor. The compressor compresses the secondary steam and transports it to the shell side of the heat exchanger for use as evaporator heating steam, realizing thermal energy circulation and continuous evaporation.

The main equipment of the forced circulation MVR evaporator consists of a heater, a separation chamber, a compressor, a circulation pump, and a filtration system. The so-called forced circulation refers to the forced circulation of the material between the heater and the separation chamber driven by the circulation pump. The material is heated when flowing through the heater, and the temperature rises appropriately. When circulating to the separation chamber, the static pressure is reduced and it begins to boil and vaporize, the solution is concentrated, supersaturation is produced, and the crystals are saturated and precipitated and grow.

The forced flow of materials between the heat exchange tubes enhances the heat transfer coefficient, especially the crystal slurry containing crystals properly flushes the heat exchange wall surface, which can significantly inhibit scaling caused by hardness (the design of the forced circulation MVR evaporator designed by Kang Jinghui has avoided the occurrence of scaling and pipe clogging of crystal materials in the heat exchanger).

1. Suitable for materials with high viscosity or containing particles;

2. Suitable for various crystallization methods with large concentration ratio;

3. Large circulation volume, high pipeline flow rate, not easy to dry wall or scale;

4. Higher energy consumption compared to falling film.

Suitable for material concentration and pre-concentration of salt crystallization, a widely used evaporator type, especially suitable for solid precipitation or special evaporation crystallization conditions during evaporation. The material in the evaporator is driven by external force to circulate heat exchange, which is especially necessary for controlling solution supersaturation and cultivating crystals.

(1) It has a very high energy efficiency ratio;

(2) It has a wide range of application scenarios, and is resistant to salting out and scaling;

(3) It is the preferred equipment form for the crystal growing evaporator, with large crystal size and narrow distribution;

(4) It is suitable for most material evaporation and crystallization occasions: sodium chloride, sodium sulfate, sodium phosphate, ammonium chloride, cobalt sulfate, cobalt chloride, nickel sulfate, ammonium sulfate, sodium thiosulfate, sodium fluoride, sodium sulfite, lithium hydroxide, sodium nitrate, potassium nitrate, ammonium nitrate, copper sulfate, calcium ammonium nitrate, barium nitrate, sodium bromide, potassium bromide, zinc sulfate, sodium borate, various organic material evaporators, etc.