Thermal Performance Study And Applied Assessment Of New Type Crystallizer With Helical Ribbon Impeller

Currently in operation of crystallization, there is the ubiquity of poor heat transfer performance, the longer reaction time, uneven crystal size, irregular grain shape. Especially for the uniformity of temperature and concentration in large crystallizer, therefore, the study and reconstruction of crystallizer about energy saving and efficiency improvement has important practical significance.Based on the knowledge of crystallography and crystallization equipment, crystallization mechanism of citric acid were studied, structural characteristics and heat transfer coefficient calculation formula of double helical ribbon impeller and jacket with spiral plate were introduced. Through the analysis of enhanced heat transfer mechanism and thermal calculation model, reconstruction design of the crystallizer in a citric acid plant was conducted, agitation component of crystallizer used double helical ribbon impeller instead of gate impellers, adopted jacket with spiral plate instead of common jacket. The structure design and technological calculation of new type crystallizer were completed. The calculation results show that the heat transfer coefficient of tank side improved 2.5 times, and the heat transfer coefficient of jacket side improved 5.5 times. Fluent software was also used for numerical simulation of double helical ribbon impeller and jacket with spiral plate, comparison of flow field and temperature field distribution, further proved the significant enhanced heat transfer performance and hydrodynamic performance of crystallizer.Finally, application and assessment of new type crystallizer were carried out. Field data tests results show that, compared with crystallizer before reconstruction, the heat transfer effect significantly enhanced, and the success of this reconstruction. The research in this paper provided technical basis for the future design of crystallizer.