Abstract
A suggestion for more efficient utilization of the available energy in single purpose distillation desalination units is presented. It includes the introduction of a vapor thermo-compression multi-effect unit to replace the pressure reducing valves and/or the superheaters usually used at the brine heaters. Furthermore, using the VTC/VTE configurations would allow raising the top effect temperature up to 136°C.
The combined system including the VTC/VTE is analyzed and some practical cases are investigated. Thermodynamic analysis showed an increase in the fresh water production by up to 100% with extra heat input of only about 19% of the original plant heat requirements. In the analysis, subatmospheric effects were not used in order to avoid the interference between the jet booster of the vapor compression and the steam jet ejector required to evacuate the non-condensable gases.
A flow sheet for the combined system is presented and the operating flexibility is pointed out. Such a system can operate efficiently with favorable response to heat input and demand changes.