ADAPTATION OF THE MULTIEFFECT-DISTILLATION (MED) PROCESS TO YIELD HIGH-PURITY DISTILLATE FOR UTILITIES, REFINERIES AND CHEMICAL-INDUSTRY

A unique design of the MED effects (evaporator/condensers) was develop ed in order to minimize energy losses and space requirements for optim al carry over separation properties as required to achieve high qualit y distillate. The design of this evaporator is characterized by very l ow thermal loads, by coaxial and very low velocity vapor flow and a ve ry compact utilization of heat transfer areas and carry-over separator devices. This paper describes the properties of the MED evaporators, the results regarding purity of distillate and minimal energy requirem ents as achieved by MED commercial plants utilizing low temperature he at sources and by mechanical multi-effect vapor compression (incorpora ting the same evaporators) using unique water vapor compressors and ut ilizing mechanical energy. Several examples of recently commissioned p lants of the two types (MED and MVC ME) operating to supply distillate at purities of 5 to 1 ppm will be presented including a detail of spe cific energy consumption and operational costs breakdown when using se a water for high purity distillation.