INCREASING THE EFFICIENCY OF THE PNEUMATIC SEPARATING DEVICE OF A GRAIN PRE-CLEANER

An increase in the productivity of pneumatic systems of grain cleaners is achieved by increasing the size and number of pneumatic separating channels. But as the channel depth increases, the non-uniformity of the air flow velocity field in the separation zone increases too, and an uneven air flow is formed in the outlet of the pneumatic separating channel, due to the action of centrifugal forces, which negatively affects the quality of grain cleaning. The purpose of the study is to improve the quality of grain material cleaning with an air-separating device of a grain pre-cleaner by equalizing the air flow in the upper part and the front part of the air-separating channel outlet by installing a guide vane in the outlet and optimizing its parameters. The authors measured the air flow rates in the pneumatic separating channel and its outlet in the idle mode at the laboratory installation of the pneumatic system of a grain pre-cleaner, as well as analyzed the cleaning of the artificially prepared grain mixture with a moisture content of 14%, consisting of barley grain of the Zazersky variety (95%) and light impurities (5%). The specific supply of grain material to the pneumoseparating channel corresponded to 7.94 kg/(s•m), the loss of valuable grain to waste was 0.05%. As a result of an aerodynamic study of the pneumatic separating channel outlet without a guide vane, a significant non-uniformity of the air flow was established in its initial section: the coefficient of air velocity variation along the channel depth amounted to 0.29, which exceeds the target values (0.20...0.25). Installing a guide vane with optimal parameters contributes to the alignment of the air flow in the upper part of the channel and the front part of its outlet, which has a positive effect on pneumoseparation. With the vane radius of 0.20 m, an angle of its arc of 80°, depths of the inlet and outlet sections of the inner part of the outlet of 0.105 and 0.066 m, respectively, the cleaning effect of the grain material from light impurities increases by 6.6% (from 61.2 to 67.8%).

grain pre-cleaner, air separating device, air separating channel, channel outlet, guide vane, cleaning effect from light impurities, air flow

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