Forced-circulation Evaporating Crystallizer

Sewage evaporation actually means heating sewage to vaporize water molecule in large quantity. The crystallization method is used for separating solid solutes with crystallization properties in the sewage, which actually means making the solution super-saturated through evaporating concentration to separate redundant solutes out by crystallization, wherein the crystals can be suspended without settlement until they fully grow up and then settle into the lower tapered cavity of the evaporator. The mixture of the crystals and mother liquor can be pumped out and then fed into the settling tank for cooling crystallization; and finally, the crystals in the mixture are separated by a centrifugal machine after the settlement.
 

II. Operation:
To improve the circulating strength and heat transfer coefficient, liquid is forced to circulate in a tube nest through a circulating pump, to promote solutions to be uniformly mixed, thus maintaining beneficial crystallization conditions. Under the boiling point pressure higher than that of normal liquid, the liquid is overheated, and then flows into a separator, to quickly reduce its pressure, resulting in flash evaporation or quick boiling of partial liquid; the evaporated steam overflows from the top of the crystallizer, which can be condensed by water for condensers to obtain pure water. Due to constant circulation of the liquid, its flow speed and temperature in the tube can be controlled, to meet the requirements of corresponding products without the domination of preselected temperature differences.
 

III. Features
●Long operation cycle–the boiling/evaporation process is not carried out on the heating surface but in a separator, therefore, the scaling generated in the tube nest due to incrustation and precipitation will be reduced to the lowest extent;
●Optimized heat exchange surface – the flow speed in the tube is determined by a circulating pump.
 

IV. Application
●It is applicable for the liquid easy for scaling and high-viscosity liquid;
●The forced circulation evaporating crystallizer is extremely suitable for crystallizing and evaporating industrial wastewater.
●It is suitable for crystallizing substances of which the solubility changes slightly with the temperature reduction, such as NaCl, and KBr.
 

V. Product Series
The product made of high-quality anticorrosion stainless steel is used for treating the sewage containing corrosive substances, has high production capacity, and is easy to operate and control.
1. Single-effect forced circulation evaporating crystallizer: it is applicable for continuous or intermittent evaporation and crystallization process requirements of special materials with high evaporation strength, high boiling point rising speed, large viscosity, bulk crystallization or easy for scaling.
2. Double-effect & three-effect forced circulation evaporating crystallizer: carry out energy-saving treatment on the steam consumption based on the original single effect.