Applications of Mechanical Vapor Recompression to Evaporation and Crystallization

Abstract

Over the past 10-15 years, mechanical vapor recompression (MVR) has become the preferred system in many industrial evaporation and crystallization applications, because of its economy and simplicity of operation. In most instances, the need for steam to provide heat for the evaporation and cooling water for condensing the overhead vapors is virtually eliminated; and, at the same time, a wide range of turndown is available. An MVR is generally found to be the most economical choice when there is no boiler plant available or when electrical power is priced competitively in comparison to steam. Vapor recompression is accomplished using centrifugal, axial-flow, or positive displacement compressors and these compressors can be powered by electricity, steam turbine or a gas turbine. The use of an MVR Evaporator/Crystallizer provides a comparatively low cost means of expanding the production capability of an existing evaporation plant either by adding a "stand alone" unit or by reconfiguring a multiple-effect system into several single-effect MVR's.