Theoretical study of the energy efficiency of a rotary grinder

The possibilities of energy saving in the work of a grain grinder by increasing the efficiency of interaction of raw materials with the working bodies of the machine have been studied. A rotary grinder, in which the raw material particles are destroyed solely by impact actions in the process of primary impacts by the elements of the rotating rotor and the subsequent secondary impacts on the stationary elements of the chamber, is proposed. In this case, the design parameters of the device provide the particles with contacts with the surfaces of the impact elements at angles of attack close to the right angle, which ensures high impact efficiency. Thus, each raw material particle in the impact zone experiences only two successive contacts with the impact elements, after which the processed product particles are removed from the impact zone. In this scheme of action on the raw material the rotor energy is used most rationally. The effectiveness of the proposed device is considered on the basis of the loss of kinetic energy that occurs when the particles hit the surface of the working bodies. The interaction of the raw material with the rotor and chamber elements is studied as a single interrelated process, and the set of shock elements of the rotor and chamber are allocated as a structural unit. An analytical expression was found that determines the total energy cost required to implement the impact forces in the proposed device. A criterion that characterizes the efficiency of the grinder in the consumption of mechanical energy for the destruction of raw materials by impact forces is also introduced. A comparison of the efficiency of the proposed device and the centrifugal crusher, in which crushing of raw materials is also carried out by impact effects, is performed according to the introduced criterion.

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