Hydrodynamics of oats fluidized layer during roasting with superheated steam

Abstract

It is necessary to know the basic hydrodynamic parameters of the material layer for proper organization of oats drying and roasting in fluidized mode, as well as when dryers and roasting plants designing. They serve as a good evaluation of the structure of the layer and contribute to the determination of optimal modes of coolant supply, in which a greater mobility of the material particles in the layer is created. The hydrodynamic characteristics of the fluidized layer were determined from the change in the resistance of the layer, depending on the vapor velocity and the specific load of the product on the gas distribution grid, as well as on the change in the height of the fluidized material layer, depending on the vapor velocity and the height of the fixed layer. The study was carried out in the following ranges of technological parameters: air temperature 343-373 K, steam temperature 383-413 K; the flow velocity of the coolant at the entrance to the layer is from 1.8 to 3.0 m / s; specific load of the product on the grate is from 15 to 30 kg / m2. The fluidization speed of oat grain, porosity and pressure loss of superheated steam in the fluidized layer of the material were determined. The deviation of the experimental data from the calculated data did not exceed ±18%. Graphic dependencies of the degree of expansion and homogeneity of the oat grain layer were obtained. It was shown that an increase in the specific loading of the oat layer on the grate contributes to the formation of a more homogeneous structure of the fluidized layer. Analysis of uniformity and equality of fluidization of a monodisperse layer of oats allows to evaluate its quality and to choose the optimal hydrodynamic regime for the drying and roasting process.