Karamushko A. Improvement of technological process and equipment for dry cleaning of air from polydisperse dust

The dissertation presents the results of research on the development of a combined dust collecting apparatus (DCA) from polydisperse dust, which combines several principles of dust collection. The design of the DCA was obtained by changing the classical scheme of the smoke exhauster-dust collector: the cyclone was excluded from the circuit, and the fan was connected with a dust-collecting container (hopper) via a circulation channel. In the proposed scheme, a dusty stream circulating in a closed circuit does not pass into the fan impeller, at the same time the wear of its blades is slowed down. The use of centrifugal pumping equipment for concentration, coagulation of dust allows to intensify the process of air purification by changing the initial dispersed composition of the dust, and the circulating scheme of the dust-gas stream eliminates from input of pollutants into the air. The dust clearing efficiency improvement of circulating flow with taking into account the reduction of the number of structural elements of the aspiration system is proved. The main structural elements in the dust collecting apparatus are different curvatures rotations by the angle φ = π around the horizontal axis where significant inertia forces operate. Velocity fields of curvilinear flow, obtained by computer simulation, proved the ability of increasing quantitative indicators of dust removal by changing the permanent cross-section turning from φ = π to the confuser-diffuser cross section. For reliable operation of centrifugal pump equipment under high concentrations of dust in the gas stream, DCA is combined with the unloader – the vortex chamber that is connected with dust collector container by circulating contour. So we have a dust collection system with two bins. For circulating and a direct-flowing system with two bins using theory of Markov processes , probabilistic models are constructed. Efficiency of replacement of direct-flow systems by circulating aspiration systems was confirmed. A removal of solid particles from the dust stream takes place in two stages. In the first stage, dust particles are carried out in deposition zone (dust container) due to the centrifugal force and separation efficiency is determined by the impeller parameters. In the second stage deposition of dust particles by gravity is occured, where separation efficiency is determined by the optimally selected construction dimensions of the hopper. To investigate the impact on dust collection efficiency of inertial and gravitational cumulative action deposition mechanisms the gravity cameras method of calculation was used. The aerosol distribution efficiency in the dust-collecting system with different variants of its elements layout is determined. By summarizing the results of the dust experiment, using the Pi-theorem, dependence for determination of the useful volume of the DCA bunker from technological and physical-mechanical parameters of the dust-gas stream is obtained. The calculation method of operational DCA characteristics by using differential distribution curve for dust mass and partial deposition coefficients of certain sizes is proposed. The dissertation results can be applied to DCA design, their use in circulating dust collectors systems will allow to reduce the level of environmental hazard, formed by air pollution.