Gas distribution device of the fluidized bed apparatus

Abstract

A common scientific problem is that the monographs of leading scientists provide very modest recommendations for the calculation and design of gas distribution devices in fluidized bed apparatus.
 So, in the monograph of P.G. Romankov and N.B. Rashkovsky, hydraulic resistance of the switchgear is advised to be taken equal to half the hydraulic resistance of the fluidized bed. This recommendation does not take into account such factors as: the specific gravity of the fluidized product, the rate of fluidization and removal of small particles of the product, and the geometric parameters of the gas distribution device.
 In the monograph of B.S. Sazhin, it is recommended that a pressure drop on the gas distribution device is taken not less than 1000 Pa. What parameters should induce such a pressure drop is not specified.
 In the work of V.M. Marchevsky and R.N. Zherebkina, the dependence connecting the hydrodynamic stability of the fluidized bed with the area of the "living" section of the openings in the gas distribution device and with the parameters of the velocity regime of the fluidized bed was obtained experimentally. The value of the hydrodynamic stability was taken as the difference in the bed heights at which the fluidization of the higher layer ceased.
 The obtained dependence allows calculating the cross-sectional areas of the openings for the passage of the coolant, but does not allow calculating the design of the gas distribution device: in particular, the configuration and number of openings, their location, pitch and hydraulic resistance. Experimental studies are needed for their calculation.
 The unsolved part of the scientific problem is that it is not possible to find an exact theoretical definition of the hydraulic resistance coefficients; their values can be found only experimentally.
 Experiments and literature data show that the hydraulic resistance coefficient does not depend on numbers Re ≥ 1000. The main factor influencing the value of the hydraulic resistance coefficient is the ratio F / F1, where F is the cross-sectional area of the lattice holes and F1 is the cross-sectional area of the apparatus.
 Analysis of the parameters presented in this paper confirms that the value of the hydraulic resistance coefficient increases with increasing according to the linear law . Segment 0 - 1, which cuts off the approximating line on the y-axis, reflects the hydraulic resistance coefficient of the columnar grid.
 The obtained equation describes with sufficient accuracy the dependence of the hydraulic resistance coefficient on the parameter in the range of . The standard deviation of the experimental values of the hydraulic resistance coefficient from the calculated one is σ = 0.075.
 It is established that the main factor influencing the value of the hydraulic resistance coefficient is the relative area of the "living" cross-section of the openings in the gas distribution device.