Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms, which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The main factors are identified that influence the performance. The results are of interest to experts in related areas of industry such as building materials and engineering ceramics and so on.The general and fractional breakthrough coefficients K and K j are major working characteristics of granular dust trapping filters in refractory production. The breakthrough coefficient isin which z i and z f are the dust contents of the gases or ventilation discharges before the trap and after it respectively in g/m 3 . The effects of actual conditions on the values of these quantities are so varied that it is impossible to present a unified and theoretically sound method of determining them. It is best to use interpolation models in the ranges for the actual physicochemical parameters of the flow and the geometrical characteristics of the trap. It has been found [1] that in generalin which w is the linear velocity of the dusty gas flow in m/sec; d e is the equivalent diameter of the pore channels in the filter layer in m; H is the thickness of the filter material in m; t is the filtration time in sec; d m is the mean median diameter of the dust particles in m; and s is the standard deviation of the logarithm for the particle diameters in a log-normal distribution (LND).Under those conditions, it is sound to plan an experiment to construct interpolation models by the Box-Wilson method with successive realization of short series of experiments on varying all the factors simultaneously. This enables one to approach the region of the optimum rapidly. In the experiments, the model dust was a polydisperse aerosol, which was used as two types of quartz dust with the following LND for the particle sizes: d m = 3.7´10 -6 m, s = 0.405, and d m = = 20´10 -6 m, s = 0.280; the factors d m and s are almost uncontrollable separately, so they are combined in a single control factor d m s. Table 1 gives the conditions, the planning matrix, and the results from the first series of experiments.In accordance with (2), we used the natural valuesx for the factors w, d e , Í, t, z i , d m s, which are denoted respectively byx 1 ,x 2 ,x 3 ,x 4 ,x 5 ,x 6 ; the encoded factors, variation levels, regression coefficients b i , and errors in determining them have been calculated by the method of [2]. Table 1 also gives the experimental values of the response function y = lnK -1 . The regression equation after checking the model for fit takes the form It follows from (3) that in these variation intervals for the factors, K increases with w and d e but ...
It has been shown [ 1, 2] that there are major advantages in separating an aerosol containing a nonsticky solid dispersed phase in a centrifugal field, and kinetic studies have been performed and a working nomogram has been proposed for determining the regeneration parameters for a continuously operating rotating filter. However, a filter of that type has an elevated energy demand, so its parameters must be optimized. The optimization criterion can be the minimum energy consumption per unit volume of dusty gas passing through the filter provided that the deposit on the rotating filter is retained only by the gas pressure difference. Then part of the total pressure difference is used to retain the deposit, while part is used in the filtration proper.When a centrifugal field is imposed, the porosity of the deposit is increased by the expansion of the layer, and then the pressure difference consumed in filtration Apd.dy n is less than the pressure difference in the static filter APd.s t by the amount Apc, which is determined by the centrifugal force acting on the deposit (here and subsequently, the subscripts are as follows: d deposit, dyn dynamic, st static, c centrifugal, cr critical, in internal, and fm filter material).That approach is quite realistic because Apd.dy n and APc act on the deposit in opposite senses. We subsequently neglect the gravitational forces acting on the deposit because APc that is comparable with Apd.dy n is 100 times at least the gravitational force even for the minimal separation factor in the centrifugal field (K = 100).We use Darcy's law [3] for the deposit on the rotating filter to get Apd.dy n = lt.tWZd.dy n ,where/a is the dynamic viscosity in Pa.sec, w the filtration speed in m/sec, and Zd.dy n the resistance of the deposit, m -1. Then the following is the pressure difference across a deposit layer of infinitely small thickness dh for w = constant, as in the industrial filtration of an aerosol:where in accordance with the [3] data, Za.dy n = Z,(Apd.dy n)sis the specific resistance of the deposit in m -2, z' is an experimental determined constant, s the deposit compressibility parameter, and o3 the angular velocity of the rotating cylindrical filter in sec -1.It follows from [ 1] that we have for a rotating cylindrical filter that Apd_dy n = Apd.s t --0.5Pd0~2h(2Ro + h),All-Russia Gas Technology Association and Semiluki Refractories Plant.
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