Haidai S. Hydrodynamics in fluidized bed granulators when obtaining organic-mineral fertilizers. – Qualification scientific work on the rights of a manuscript.
The dissertation for the scientific degree of candidate of technical sciences (for
the Ph.D.), specialty 05.17.08 – processes and equipment of chemical technology. – National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute" of the Ministry of Education and Science of Ukraine. Kyiv, 2018.
The dissertation is dedicated to solving the important scientific and technical problem – increasing of efficiency of the process of obtaining innovative granular organic-mineral fertilizers that are necessary for the implementation of the principles of rational land use through the application of non-uniform fluidization in auto-oscillating mode.
The efficiency of application of non-uniform fluidization in an auto-oscillating mode in the process of dehydration and granulation of liquid heterogeneous systems is theoretically substantiated and experimentally proved. The regularities of the transition of the bubbling hydrodynamic mode of fluidization to the non-uniform auto-oscillating and rational limits of its existence are established.
In the work are proposed the criteria for assessing the quality of hydrodynamics in the auto-oscillating mode of jet-pulsed fluidization in the form of a function of loss of a hydrodynamics quality and the index of dynamic quality of hydrodynamics, which allows to determine the technological parameters, which minimizes the risk of formation of stagnant zones on the work surfaces of the gas distributing device, which increases the stability of granulation processes with the use of heat carrier with a temperature of more than 300 oC.
The conditions of existence of an auto-oscillating mode of jet-pulsating fluidization, which provide the index of dynamic quality of hydrodynamics iquality ≥ 0,85 for solid particles in the range of values of equivalent diameter 1,5 ≤ de ≤ 4,0 mm are determined. The functional dependence of influence of the hydrodynamic mode of heat carrier movement in the slits of the gas distributing device, the number of fluidization and the dispersion of a bed of granular material on the dynamic quality of hydrodynamics is established. The generalization of an experimental data is carried out in the form of functional dependences of the frequency of pulsations of granular material bed and the index of mixing of a fluidized bed on the number of fluidization and the dispersion of bed from 1,5 ≤ de ≤ 4,0 mm in the application of non-uniform jet-pulsating fluidization in an auto-oscillating mode with the ratio of a height of the torch of a jet zф to a height of the fixed bed H0 – zф/H0 < 0,5.
The verification of the reliability of physical and mathematical models was carried out at the pilot plant during the study of the kinetics of the process of granulation of organic-mineral fertilizers based on ammonium sulfate, sunflower ash and humic impurities. The results of the experimental studies have shown that the use of the non-uniform fluidization in an auto-oscillating mode allows to increase the specific load of the bed's surface over moisture in 1,5 times compared to the bubbling regime with granulation coefficients ψ ≥ 90 %. The obtained granular product is with spheroidal shape with a layered structure with an equivalent diameter of 2,5 mm and a strength of 16 N per granule, which is in 1,6 times bigger than the current standard. At the same time, the total height of a bed was pulsatingly increasing in 1,7 ... 2,0 times, relative to the height of the fixed initial bed H0 with the corresponding proportional increase of potential energy. At the same time, the coefficient of the bed of material displacement in one cycle is reached to 70 % and the index of dynamic quality of hydrodynamics is iquality ≥ 0,85. Reliability of the developed method for assessing the quality of the hydrodynamic mode of fluidization is confirmed by the absence of stagnant zones of solid particles on the working surfaces of the gas distributing device when applied the heat carrier with a temperature up to 300 °C in a real processes of granulation.
Key words: organic-mineral fertilizers, granulation, non-uniform fluidization, auto oscillation, liquid heterogeneous system.
