Energy Saving Research on Multi-effect Evaporation Crystallization Process of Bittern Based on MVR and TVR Heat Pump Technology

This work keeps an eye on the energy saving research on evaporation crystallization process of bittern. Based on the thermo sensitivity of solubility of various salts in bittern, the magnesium salts are purified. The conventional evaporation crystallization process used to separate the bittern demands high energy consumption and has low thermodynamic efficiency. Therefore, the multi-effect evaporation (MEE), thermal vapor recompression (TVR) heat pump and mechanical vapor recompression (MVR) heat pump technology were applied to the conventional evaporation crystallization process. The MVR and TVR technology can both make full use of the secondary steam heating materials that will save energy. In addition, Aspen Plus (Version 7.3) was used to simulate the processes of the electrolyte-containing system under the ELECNTRAL thermodynamic model. For the better evaluation of various evaporation crystallization processes, some important evaluation indexes, such as energy consumption, annual total cost (ATC) and exergy loss were chosen as objective functions. Compared with the double-effect evaporation crystallization process coupled with TVR heat pump technology, the results indicated that the double-effect evaporation crystallization process coupled with MVR heat pump technology can save energy consumption and ATC by 80.52% and 15.32% respectively. Furthermore, the MVR heat pump technology takes the lowest effective energy loss, which is a more competitive factor of evaporation crystallization process of bittern.