Analysis of mechanical vapour compression desalination process

Characteristics of the single-effect mechanical vapour-compression (MVC) ar e analysed as a function of the system design and operating parameters. The analysis focuses on prediction of the specific power consumption for the v apour compressor and the specific heat transfer areas for the evaporator/co ndenser unit and the plate-type feed preheaters. The mathematical model inc ludes material and energy balance equations as well as a set of correlation s for evaluation of the thermophysical properties and the heat transfer coe fficients. The correlations are dependent on the transport properties of th e flowing streams, i.e. temperature, concentration, and velocity. In additi on, the model considers the effects of the boiling point elevation and the pressure losses in the demister. Results show decrease in the specific powe r consumption and the specific heat transfer area of the evaporator/condens er at higher top brine temperatures. On the other hand, the specific power consumption decreases at low-temperature differences between the boiling br ine and steam condensate, while the specific heat transfer area increases. Model predictions are found consistent with the available industrial data. Finally, comparison of the performance of the MVC system and the single-eff ect thermal vapour compression (TVC) is made as a function of design and op erating parameters. Although, the results show comparable performance, choi ce between the two systems should take into consideration other operational parameters. Copyright (C) 1999 John Wiley & Sons, Ltd.