Technological aspects of the development of thermal vacuum installation for drying grain with simultaneous dehydration and disinsection

Abstract

The Ukraine is one of the largest producers of grain products. Its natural and climatic conditions are such that annually from 50 to 80 % of the harvested crop of grain crops is subject to drying and disinfection. Drying and simultaneous disinsection of grain are the main technological operations for removing harmful moisture from grain material and freeing it from barn pests, which on a national scale makes it possible to avoid millions of losses. The article provides materials on the development of a highly efficient environmentally friendly installation and energy-saving technology of dehydration with simultaneous disinfection of wet grain, which makes it possible to dry grain in a short period of time to a moisture content of 12...14 % and destroy pests. A brief review discusses the main drying units, which are of the convective type and mainly use heated air. Their main positive and negative aspects of use are analyzed. An experimental model of the developed highly efficient environmentally friendly grain drying plant with physical and mathematical justification is presented. Thus, at the same time, such indicators as the speed of grain swirling (υВ) at different temperatures, the value of the centrifugal force of the grain (F) moving in the cavity of the heating element through a spiral channel were calculated. The instantaneous process of thermal energy transfer from the heater wall to the wet grain is substantiated.Thus, the surface element (dS) of a wet grain receives a flow of thermal energy (dQ) with a temperature (Т) in a short period of time (∆τ) with a heat transfer coefficient (a). It has been experimentally proven that grain dehydration is affected by at least three parameters: the heating temperature, its humidity, and the pressure in the vacuum chamber. All parameters are interconnected and affect technological indicators. Thus, the use of thermovacuum technology is an alternative to traditional high-temperature methods of drying grain crops. Key words: thermovacuum dehydration of grain, drying, disinsection.