Regarding crystallization and cooling?
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Hello everyone. I am involved in the production of feed additives, but there are some problems that arise during the production process; for example, when concentrating the solution, high temperatures and high vacuum levels are encountered yet the desired results are not achieved. I hope you can offer some suggestions to help resolve these issues. Another issue is that during crystallization, the crystal particles are small, the cooling effect is poor, and wall sticking occurs – a problem that has yet to be resolved. Could everyone please help by suggesting some solutions? Thank you so much! ! ! !
Please talk to me in detail about the specific situation.
Reply to 2# ll96129: The specifics are as follows: Concentration is carried out using a vacuum level of over -0.06 MPa and high temperatures of 95–110°C; theoretically, the results should be very good. However, the current concentration time is around 15 hours for a volume of 4 m³, which is quite long (theoretically, it should be shorter)； Furthermore, after concentration is complete, cooling and crystallization take place; as a result, the crystals formed are small and difficult to dry. The cooling process for crystallization lasts over 10 hours (the equipment is in good condition and the cooling circulating water is supplied properly). Sometimes, sticking to the walls of the crystallization tank occurs, with a thick layer forming on those walls, which hinders heat transfer. Could the hero help solve this problem? :handshake
Based on the situation you described, concentration should be carried out first, followed by cooling for crystallization. The solute content in the solution is likely to be high, which accelerates the crystallization process and results in smaller crystal particles； While crystallizing, it is necessary to address the mixing issue properly, otherwise crystal growth on the walls will occur.
What was said upstairs makes sense! As a supplementary point, in addition to considering the stirring line speed, it is also necessary to ensure that there is not too large a difference in temperature between the cooling water and the material mixture; ideally, there should be automatic control to regulate the temperature difference between the two ；
Reply to 4# Shell Ham: The problem that needs to be solved now is: how can we achieve an ideal cooling effect without the formation of deposits on the walls?
Reply to 5# rujunsun: We have considered this as well, but if the temperature difference between the warm water and the temperature of the liquid material is small, the cooling effect will be even less satisfactory. The problem now is how to address the slow cooling rate! Depresseding……
What feed additives? We have installed three sets of concentration crystallization systems in Shandong; crystallization takes place directly at high temperature, without the need for cooling. The performance is quite good, and energy consumption is low as well. Your vacuum really isn’t that good.
If it is determined that the cooling rate is slow, the flow rate of the cooling water in and out can be increased, or the flow rate of the feed and product fluids can be reduced； so. . .
Reply to 9# rujunsun: In that case, the problem of small crystal particles will arise……
Reply to 8# wuhanzzm: Heat crystallization could indeed be considered, but we still need to carry out a centrifugation process. In that case, when heat crystallization occurs and the mixture cools down, it may cause blockages in the filter pores of the centrifugation equipment, which I think would be quite troublesome