Abstract: A process for concentrating a cold liquid dairy product and for preheating a circulating fluid, which comprises the steps of submitting the liquid dairy product to a multi-stage evaporation by supplying a first evaporation stage with heating vapor as a source of heat for evaporation of the liquid dairy product in the first evaporation stage to convert the heating vapor to condensate and produce evaporation vapor from the liquid dairy product; supplying the second evaporation stage with evaporation vapor produced in the first evaporation stage so that the first evaporation stage supplies a source of heat for evaporation of the liquid dairy product in the second evaporation stage to convert the evaporation vapor supply in the second evaporation stage to condensate and produce evaporation vapor from the liquid dairy product; repeating the steps of submitting and supplying up to and including the last evaporation stage; preheating the circulating fluid by a one-step heat exchange with the evaporation vapor, the c

Abstract: A method for preheating the air circulating and used in an installation comprising a multi-stage evaporator adapted to concentrate a liquid product, in particular a food product such as a milk product, on the one hand, and a drying unit in which is processed and concentrate issuing from said evaporator, or any other concentrate, on the other hand, said method comprising the steps of heating condensates of said multi-stage evaporator by means of a fluid issuing from said evaporator and hotter than said condensates, then driving the thus-heated condensates into a heat-exchanger wherein they cause air to be preheated.

Abstract: The present invention relates to a process for providing make-up heat in a mechanical vapour recompression evaporator (1, 8, 9).It includes using the evaporation vapour created in another evaporator (5) called make-up evaporator.The invention finds particular application in the dairy industry.