2ND-LAW ANALYSIS OF RECIRCULATING MULTISTAGE FLASH DESALTING SYSTEM

A comprehensive study is conducted to analyze a recirculating multi-stage flash desalting plant based on the second law of thermodynamics. Although the first law of thermodynamics indicates the overall performance of the desalting plants, it does not show the actual losses in each process of the plant. In this work the exergy (i.e., availability) losses due to the irreversibilities in different processes in the plant are evaluated. The study shows that the major exergy losses occur, respectively, in the vapor condensation processes, the vapor flashing process, and the feed heating process in the brine heater. The other losses due to heat transfer through walls, pressure drop through demisters, and friction flow in pipes are negligible.