ENSURING GRAIN CLEANING IN BLACKOUT CONDITIONS: SUBSTITUTION AND MINIMIZATION OF ENERGY CONSUMPTION OF AIR AND SIEVE SEPARATION OF GRAIN MATERIALS

The article is devoted to the problem of ensuring effective cleaning of grain materials at minimal electricity consumption, which is relevant for wartime conditions and unstable energy supply. Based on elements of probability theory, a mathematical model of the sieve separation process for sieves with slots of variable size has been developed and the dependence of cleaning efficiency on the design parameters of the sieve and the speed regime has been theoretically substantiated. The relationship between the live cross-section coefficient of the sieve cloth and the specific energy consumption of the process has been analytically established: it is shown that an increase in the live cross-section coefficient from kl = 0,50 to kl = 0,95 reduces the specific electricity consumption from 0.35-0.55 to 0.18-0.28 kWh/t. The condition for automatic self-cleaning of sieves with slots of variable size was derived, which eliminates the need for a separate cleaning device and provides savings of 0.08-0.15 kWh/t. The theory of gravitational aspiration of the grain flow was developed: an expression for the ejection velocity of air in a vertical channel was obtained and it was shown that at a productivity of 10 t/h and a free fall height of 1.0 m, an air flow velocity of ≈ 0.94 m/s is achieved, sufficient for the separation of light impurities without external energy consumption. It is substantiated that the use of string screens with a live cross-section coefficient of 93-99% in combination with a gravitational aspiration zone allows reducing the total specific electricity consumption from 0.75-1.20 to 0.18-0.35 kWh/t (savings of about 74%). The concept of a minimum-energy grain cleaning machine based on four functional blocks is proposed: a string screen, a lightweight vibrating screen, a gravitational aspiration zone and a LiFePO4 battery power module with a capacity of 10-20 kWh, suitable for power supply from battery stations or photovoltaic panels in conditions of power outages.