METHOD OF AUTOMATIC CONTROL OF DRYING PROCESS Russian patent published in 2000 - IPC

FIELD: automation of production processes; automation of process of drying thermolabile products, grain for example. SUBSTANCE: method includes preheating of moist product by flow of treated drying agent followed by drying the product in evaporator and heating it in condenser of thermal pump plant and feeding it to drier, thus forming closed cycle through action on rate of flow of vapor to calorifier and on power of drive of fan and stabilization of final moisture content of product by moisture content of drying agent at drier inlet, as well as stabilization of heat transfer coefficient of evaporator of thermal pump plant by relationship of flow rate of drying agent and cooling agent at evaporator inlet through change of flow rate of cooling agent by action of power of compressor drive. After dehumidification of drying agent in evaporator of thermal pump plant, it is first fed to recuperative heat exchanger for preheating and them to condenser of thermal pump plant, after which it is fed to closed cycle. Replenishment of drying agent is effected before evaporator. Besides that, temperature of drying agent after evaporator and before condenser is measured. Preset cooling capacity of thermal pump plant is determined by difference of temperatures through action on power of compressor drive at continuous double correction by heat transfer coefficient on cooled surface of evaporator of thermal pump plant and moisture content of drying agent at drier inlet; stabilization of final moisture content of product is effected by action on flow rate of moist product fed for preheating. EFFECT: reduced specific power requirements; improved quality of dried product. 2 cl, 1 dwg