Selection between evaporation crystallization and cooling crystallization
Thread Content
Gentlemen, when it comes to online posts, if the solubility changes significantly with temperature, cooling crystallization is the preferred method; otherwise, evaporation crystallization is chosen； For the existing saturated solution after evaporation, crystalline products are required. The solubility of the solution decreases as temperature drops; it contains no crystal water. However, during cooling and crystallization, a large amount of mother liquor is produced, which needs to be recovered and reused. All the water in the solution still has to be evaporated. Evaporation crystallization results in high energy consumption per cycle, but it produces less mother liquor with a higher concentration. I have a question: in this situation, should evaporation crystallization or cooling crystallization be chosen?
It mainly comes down to calculating production capacity and energy consumption. It is possible to calculate it for complete cooling, complete evaporation, as well as partial cooling and partial evaporation.
It is necessary to consider technical feasibility and economic rationality, and handle each specific issue on its own.
Treat each specific issue individually; it’s necessary to do the calculations to find out
Generally, it depends on the solubility of the solution; for example, if the solubility changes significantly with temperature, cooling crystallization is a more suitable option
For evaporation crystallization and cooling crystallization, economic analyses are necessary. In cooling crystallization, the amount of mother liquor is large, requiring re-concentration; moreover, many side reactions can occur in some products, affecting their quality； If evaporation crystallization involves steam concentration, it is not advisable, as it also generates a large amount of by-products. Currently, there are vacuum crystallization and phase-change evaporation crystallization methods, but one requirement is that the vacuum level must be very low, which results in high energy consumption. Take economic analysis into comprehensive consideration.