Mathematical Simulation of Sediment Kinetics in a Continuous Centrifuge
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MATHEMATICAL SIMULATION OF SEDIMENT KINETICS IN A CONTINUOUS CENTRIFUGE E. V. Semenov, A. A. Slavyanskii, K. V. Galko, and A. A. Kopteva
UDC 66.021
A kinetic equation (in vector form) for the displacement of a given aggregate of solid particles under the effect of force factors is formulated on the basis of the law of conservation of momentum for an aggregate migrating around a conical perforated rotor. The kinematic characteristics of the aggregate as it travels along the conical surface of the rotor as well as the values of the final velocity of a test particle with given physico-mechanical and geometric parameters as it comes into collision with a receiving apparatus are quantitatively analyzed on the basis of a solution of the equation. Moreover, if the final velocity of the particle exceeds the critical velocity calculated for it on the basis of the theory of cracking, then, based on the calculation, preconditions for the destruction of the test particle once it collides with the receiving apparatus of a centrifuge are created. Key words: continuous centrifuge, aggregate of particles, movement of center of mass, impact, crack.
Continuous centrifuges are used in industry to separate liquid systems with a broad range of values of disperseness and concentration of solid phase: for example, in the chemical branch to form suspensions, including soluble solid-phase crystals (potassium and sodium chlorides, copper sulfides, ammonium carbonate, etc.) and in the food branch to process sugar massecuites of different crystallizations in sugar and starch production. The advantages of continuous centrifuges include the simplicity of the design, the possibility of automatic control, and the high level of quality of washing of the solid phase of the suspension. Questions of the design and application of continuous as well as periodic industrial centrifuges for separation of liquid mixtures have been discussed in many studies [1−5]. The advantages of continuous centrifuges as compared to periodic centrifuges include the ease of installation into a high-productivity continuous technological flow (economically more efficient flow), lower cost of fabrication and simplicity of use. Unlike periodic-type centrifuges (with “soft” conditions of separation of the solid phase from the suspension), however, in continuous-type centrifuges the largest particles of the solid may experience abrasion as they travel over the sieve surface and then are pulverized as they collide with the receiving apparatus (upon breaking away at high speeds from the deposition surface in traveling towards the shell of the rotor), which leads to a drop in the quality of the processed article. Sufficient attention has not been devoted in published studies to these features of the course of processing a suspension in a continuous centrifuge (in particular, from the standpoint of optimal control of the process), hence deeper study and scientific and engineering critical analysis of these features are critical needs. The objective of the present study is to inves
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