Improving the mechanical-mathematical model of grain mass separation in a fluidized bed

Abstract

This paper has substantiated the prospect of modeling the processes of separating grain mass into fractions as one of the tasks in the production of high-quality seed material. It has been determined that this could optimize the parameters of separation processes and design new working surfaces for its implementation. It is noted that modeling should take into consideration the influence of the structural and kinematic parameters of grain cleaning machines, the physical and mechanical properties of raw materials, the intralayer processes and forces. The reported theoretical study has improved the mechanical-mathematical model of grain mass separation in a pseudo-fluidized bed according to its density. The model establishes a relationship between the effective coefficient of dynamic viscosity and the density of particles in the discrete and continuous phases and the volumetric concentration of discrete phase particles. At the same time, the porosity of a fluidized bed has been accounted for, as well as the longitudinal and transverse angles of inclination of the base surface to the horizontal plane, the amplitude and frequency of oscillations of the particles of the continuous phase; the direction angle of oscillations relative to the perpendicular to the base surface. The adequacy of the improved mechanical-mathematical model has been confirmed by comparing the experimental and theoretical results of grain mass fractionation modeling. It was found that the differences in the density values of the separated fractions of GM did not exceed 7...8 %, that is, they were within the margin of error. It has been established that the improved model of grain mass separation in a fluidized bed could be used to determine the rational values for the parameters of a pneumatic sorting table that is used for the fractionation of the corresponding seed material. The initial data, in this case, are the density of the continuous and solid phases of grain mass, the friction coefficient of the seeds, and the equivalent radius of the particle. The result of modeling is the rational values of the amplitude and oscillation frequency of the working surface of the pneumatic sorting table, and the angles of inclination of the working surface

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

“…Then, the magnitude of the moment acting on the grain will be determined by the force of aerodynamic resistance and its shoulder relative to the center of mass. With a power-law distribution of air velocity along the Ox axis, the value of the shoulder l can be taken as a variable according to the linear dependence [1,11,28]:…”

“…To increase the efficiency of separating grain material, structural improvements are used in the form of guide grids in the upper part of the channel to equalize the air flow [11][12][13]. However, this is ineffective, since the dense flow of grain material at the inlet to the air flow increases the air speed in the intergrain space unevenly, and the uniformity of the air flow speed is violated.…”

“…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.…”

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

“…One of the techniques that has proven effective during the mechanical-mathematical modeling of GM separation process [12] is to apply the concept of the hydrodynamics of multi-phase media. Under a given method, a fluidization medium is characterized by dynamic viscosity, and GM is represented by a two-phase liquid.…”

The Grain Cleaning Production Lines’ Energysaving Operation Modes of Electromechanical Systems

“…A review of electric motor current state of the modeling and analysis methods does not answer this question (Bilgin et al, 2019). Research on improvement of mechanical and mathematical model of grain separation in the fluidized layer confirmed the suitability of the model when comparing the experimental and theoretical results (Bredykhin et al, 2021).…”