ПСЕВДООЖИЖЕНИЕ СЕМЯН ПРОСА И ГОРОХА

Abstract

One of the convective drying methods used to intensify the process of drying granular materials is the use of a device with a fl uidized bed. The essential advantages of fl uidized bed dryers are the uniform drying of all the particles in the bed and the ease of loading and unloading the material. The study goal was to conduct an experimental study of the hydrodynamics of the fl uidized bed of millet and pea seeds and the determination of the fi rst critical velocity (the rate of the beginning of fl uidization) based on these data. The authors took small (millet) and large (pea) seeds for the experiment. Based on the experimental data obtained, they constructed pseudo-liquefaction curves – ΔP = f (v) for millet and peas to determine the fi rst critical fl uidization rates (0.73 m/s for millet and 1.68 m/s for peas). The experimentally found values of the fi rst critical fl uidization rate were compared with the values calculated by the equations of O.M. Todes, Wen and Yu, and Grace. The study showed that all the equations provide an acceptable accuracy of calculations, but the accuracy of using the equation of O.M. Todes is somewhat higher. Therefore it can be primarily recommended for engineering analysis. The fi rst critical fl uidization rates, calculated according to the formula of O.M. Todes, were, accordingly: 0.69 m/s for millet and 1.60 m/s for pea. The calculation and experimental data on the fi rst critical fl uidization rates for millet and peas agree satisfactorily (the relative error for millet is 5.5%, for peas – 4.8%). The suffi ciently high accuracy of the fi rst critical fl uidization rates is explained by the correct geometric shape of the studied seeds, which is close to spherical. Therefore, the fi rst critical fl uidization speed of the studied seed material can be determined using the formula of O.M. Todes.