Vertical Tube Foam Evaporation Applied for Heat Transfer Enhancement in a Commercial Plant and to Vapor Compression Distillation of Saline Water

摘要

Heat transfer enhancement by vertical tube foam evaporation (VTFE), a novel patented process for seawater/brine evaporation, was developed in the author's laboratory over the past 15 years. The process, also known as interface-enhanced vertical tube evaporation (VTE), relies on imposing foamy evaporative flow of the liquid and its vapor over a heat transfer surface. The VTFE method was applied in a two-part study by converting two pre-existing evaporator facilities for foamy mode operation and testing to compare VTE and VTFE performances. Part One describes conversion of a commercial 4-effect VTE for VTFE operation, and comparative testing with the VTE and VTFE modes with freshwater and seawater feeds. Test data showed an improvement of 40% by operation of this VTE facility in the VTFE mode. Part Two describes conversion of a vapor compression VTFE facility to a mobile facility for field operation, and similar comparative testing. Test data showed that VTFE operation gave a 27% performance improvement over conventional VTE operation and a concurrent 20% reduction in evaporative energy needed. Recommendations for further demonstration work were made to facilitate VTFE acceptance as a commercial process.