DRYING-PROCESS AUTOMATIC CONTROL METHOD Russian patent published in 2003 - IPC

FIELD: drying process automation. SUBSTANCE: method involves preheating of damp product by waste drying-agent flow followed by its drying in working section of heat-pump unit evaporator, heating first in recuperative heat-transfer apparatus and then in heat-pump unit condenser, and its supply to drier; in the process temperature and moisture content of drying agent are measured at drier inlet, closed circuit being organized; excess portion of spent drying agent is discharged or made up by fresh drying agent by varying power of fan drive and heatpump unit compressor, refrigeration capacity of heat-pump unit being corrected ; then working section is turned off for regeneration and standby one is turned on; final moisture content of product is regulated by varying flowrate of damp product supplied for preheating. In the process spent drying agent is sequentially fed upon preheating of damp product first to recuperative heat-transfer apparatus for pre-cooling due to lowtemperature potential of drying agent conveyed from working section of heat-pump unit evaporator, then it is supplied for further cooling down to evaporator section operating in regeneration mode due to heat transfer between drying agent and defrosting snow coat on cooling surface of this section and further to working section of heat-pump unit evaporator; refrigeration capacity of heat-pump unit is corrected with respect to drying agent temperature at drier inlet by varying compressor drive power; moisture content of drying agent at drier inlet is regulated by varying proportion between spent and fresh cooling agent flowrates in circulation line; to this end flowrates of these agents are varied in discharge and make-up lines. EFFECT: reduced specific energy consumption for drying process. 1 cl, 1 dwg