Hybrid desalination system of mechanical vapor recompression based on membrane distillation

Abstract

The microporous PTFE membrane was used for membrane distillation (MD) experiment and presented ultra-high efficiency of desalination. A hybrid desalination system combining membrane distillation and mechanical vapor compression (MD+MVR) had been developed on the basis of the MD experiment. The system featured that the latent heat and part of sensible heat of vapor from the MVR were recovered to heat the MD process, and the heating process occurred in the same module as the MD process. Models were built according to the energy and mass conservation for the system description. Based on the simulation and experimental data, when the system was assigned a treatment capacity 1000 kg h-1 for 1% saline water and with corresponding 875 kg h-1 fresh water production, it would be stuffed with 75.24 m2 of PTFE membrane and expense only 3.31 kW of electrical power, under 353 K of feed temperature in membrane module and 26 kPa of compressor suction pressure. The compressor power requirement would trade off the heat transfer area with variation of the heat transfer temperature difference. The higher the salinity concentration in the residual concentrate after distillation was, the higher the compressor power, membrane area and heat exchanger area would be.