A. Ophir et A. Gendel, ADAPTATION OF THE MULTIEFFECT-DISTILLATION (MED) PROCESS TO YIELD HIGH-PURITY DISTILLATE FOR UTILITIES, REFINERIES AND CHEMICAL-INDUSTRY, Desalination, 98(1-3), 1994, pp. 383-390
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.