August 2006 - Evaporation plants are used for the concentration and separation of liquid solutions in a variety of industries, ranging from the food and beverages, to chemical and pharmaceutical process industries, and in environmental applications. Particular emphasis has always been placed on reducing the amount of energy required for the operation of an evaporator, as far as is technically and economically feasible.
For this purpose, modern evaporation plants are equipped with mechanical vapour recompressors. Thanks to the use of compressors the plant efficiency is considerably optimized. All of the vapours evaporated from the product are recompressed by means of electrical energy to be reused for plant heating. Consequently, only a relatively small amount of recompression work needs to be performed, rather than requiring the entire evaporation enthalpy to be provided.
In South America, GEA Wiegand has now delivered and successfully commissioned an evaporation plant for fermentation broth, equipped with two vapour recompressors connected in series, for an evaporation rate of 111 tons/hr. Although the significant boiling point elevation has required connection of the fans in series, it has been possible to reduce the electrical power consumption per ton of water evaporation to a value considerably below 20 kW, which is an extremely favourable consumption figure for this type of application.