The influence of operation parameters on concentration ratio of multi-effect evaporation system with mechanical vapor compression

• Published in: Chemical engineering research & design 2024-04, Vol.204, p.201-211
• Main Authors: Bai, Fan, Li, Yihao, Gong, Luyuan, Zhou, Shihe, Shen, Shengqiang
• Format: Article
• Language: English
• Subjects: Concentration ratio; Desalination; Energy recovery; Mechanical vapor compression; Specific power consumption
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2024.02.038

MVC (mechanical vapor compression) evaporation technology has become a hot research topic due to low energy consumption and high efficiency. Based on conservations of energy and mass, the mathematical model of a multi-effect evaporation system with mechanical vapor compression (MEE-MVC) is established to analyze the effects of key operating parameters. The relationship between concentration ratio (CR) and specific power consumption (SPC) is revealed. Results indicate that more evaporator effects can promote the CR when the total heat transfer temperature difference keeps constant. It can be found that when the total heat transfer temperature difference is greater than approximately 10°C, the CR of different systems are almost fixed between 1.2 and 2.5, but the SPC can reach more than 15kWh/t. CR gradually increased as the temperature of last-effect evaporator secondary vapor increased, and the increase is about 0.3. In particular, by changing the total heat transfer temperature difference or the temperature of secondary vapor of the last effect to increase the CR, the SPC can be reduced and better energy-saving effects be obtained. The change of the CR with the final secondary vapor temperature is the combined effect of boiling point elevation (BPE) and latent heat of the secondary vapor. [Display omitted] •Modelling the multi-effect evaporation with mechanical vapor compression at steady and self-balance state.•Determining main factors affecting concentration ratio (CR).•Revealing the relationship between concentration ratio and specific power consumption (SPC) of MVC evaporation system.