Modeling of Aerodynamic Separation of Preliminarily Stratified Grain Mixture in Vertical Pneumatic Separation Duct

Abstract

The productivity of most grain cleaning machines seems to be directly related to the efficiency of vertical pneumatic separation ducts. Nevertheless, improvement is accompanied by an increase in the load of the vertical duct, the design of which is limited by the width of the grain cleaning machines. This requires an increase in the thickness of the layer of grain mixture that enters the working area of the duct, which significantly worsens the conditions of separation of its components under the action of airflow. Particles of light impurities are unable to separate due to their retention by the grain medium. This reduces the quality of cleaning and requires appropriate scientific and technical solutions. The application of preliminary stratification of the granular mixture while increasing the concentration of light impurities in the top layer of the mixture seems to be a prospective method. The positive effect of the previous stratification on the intensity of redistribution of light impurity particles in the working zone has been theoretically considered and experimentally confirmed. Mathematical models were obtained to determine the trajectory of discussed particles, taking into account the previous stratification of mixtures, and the corresponding dependences were established. The influence of the initial coordination of the introduction of the particles of lightweight impurities, their sizes and densities, and technological and structural parameters of operation of the pneumatic separation duct were taken into account in the studies. The intensification of the process of cleaning grain from lightweight impurities in the working zones of pneumatic separation ducts of grain cleaning machines is theoretically substantiated.

Segregation of particles during maize loading process in a center-loaded silo

“…The distribution of other organic impurities was consistent with the results reported by Salarikia et al 4 that other organic impurities in wheat mainly concentrated in the periphery of the silo. Kharchenko et al 22 also reported the same movement track of light impurities in the experiment of impurity separation of small grain heap, and the trajectory of light impurities in the separation from grain mixture was concave parabola. On the one hand, the gathering of other organic impurities near the silo wall would affect the ow characteristics of grains during grain unloading, and the possibility of arching was increased during unloading.…”

Improving the mechanical-mathematical model of pneumatic vibration centrifugal fractionation of grain materials based on their density

“…Making use of the gravitational field predetermines limited specific performance. This is one of the basic important disadvantages of such separators [5]. As a result, in order to find effective techniques for GM separation, interest in centrifugal separators has increased.…”

“…The main difference between these equations is the introduction of additional components for the mass force in (5). Indeed, the transition to relative motion leads to the addition of real mass force (gravity) by force of inertia.…”

To the Theory of Grain Motion in an Uneven Air Flow in a Vertical Pneumatic Separation Channel with an Annular Cross Section

“…Vertical flows provide a higher separation quality with small grain material feeds into the pneumatic separation channel [2][3][4]. With an increase in the supply of material, the efficiency of their fractionation decreases.…”

“…Another way to increase the productivity and quality of cleaning and fractionation of grain material in a vertical channel is the use of multi-flow introduction of grain material into the channel [3,11,[17][18][19]. At the same time, grain streams (monolayers) are formed, which create grain microchannel when the grain material is introduced into the air flow.…”