Non-uniform fluidization in auto-oscillating mode.

Introduction. The objective of this work is mathematical modeling of non-uniform fluidization in an auto-oscillating hydrodynamic mode, which will improve the efficiency of heat and mass transfer along processes of dehydration and granulation by creating an intensive directed mixing of granular material. Materials and methods. The granular material contained in the granulator chamber, equipped with a special gas distributing device in the lower part and a guiding insert in the upper. Determinations of porosity and pressure drop in a fluidized bed with video recording of the process were carried out using specialized equipment. Results and discussion. Is implemented the non-uniform fluidization in an auto-oscillating mode with the application of an original gas distributing device with a coefficient of a cross-section coefficient φ=4.9%, and an improved granulator chamber. Is provided an intensive macro mixing of granular material with an equivalent diameter of De =3.97 mm and a density ρs=1450 kg/m3 with relation of the nominal pressure drop to height of a fluidized bed ΔPbed/H0≥8500 Pa/m with a pulsating frequency f=1.67 Hz. Non-uniform fluidization in an auto-oscillating mode provides a granulation coefficient ψ≥90%, and the average specific load of the bed surface of granular material by moisture af=0.8–0.9 kgmoist./(m2·h). Mathematical model was chosen and on the basis of experimental researches was modified. The developed mathematical model with taking into account heterogeneity made possible to determine the conditions of realization a process in which up to 25% of the mass of a fluidized bed is in the active phase outside the bed with a frequency f=1.67 Hz. The mathematical model with an accuracy of 94.1% confirms the results of experimental study. Conclusions. The hydrodynamics in granulator chamber without formation of stagnant zones was realized. The modified mathematical model made possible to determine the intensity of an active pulsating and a volume circulating mixing, that will significantly increase the stability of kinetics of granule formation in dehydration of composite liquid systems. [ABSTRACT FROM AUTHOR]