USE OF THE S-40 DRYER IN TWO-STAGE DRYING OF CORN GRAIN

Abstract

The paper provides rationale for safe modes and methods for calculating a two-stage drying technology with partial recirculation of grain, in which the grain is under-dried by 2...3% to the standard humidity in a grain dryer, and the hot grain is cooled by active ventilation with outside air, while drying it to the standard humidity. The safe mode of two-stage drying in S-40 provides for partial recirculation of grain with moisture removal close to the standard, and the moisture content of the recirculated mixture not exceeding 18%. The recirculation coefficient calculated based on this condition is used to determine the temperature of the recirculating grain mixture, taking into account the reversible component in the shaft dryer. The minimized recirculation ratio provides for the permissible unevenness in drying and minimal fracturing. The recirculation drying process was analyzed according to the standard method, but with the adjusted values of moisture removal and temperature of the grain mixture. Economic tests of the S-40 dryer were carried out using a two-stage technology on corn grain. It has been experimentally established that the S-40 dryer with a recirculation coefficient of 2 and a moisture pick-up of 4% per cycle when drying corn grain with a moisture content of 23.5 to 15.6%, at a drying agent temperature of 95°C, provides a throughput of 10 t/h (without refrigeration). Cooling was carried out in the warehouse. No significant changes in the quality of dried and cooled grain have been established: the starch content and fracturing practically did not change; the unevenness of the dried seeds did not exceed the original requirements. The expediency of using the S-40 direct-flow dryer in the recirculation mode has been experimentally established.