EXPERIMENT-CALCULATING STUDY OF THERMAL DECOMPOSITION OF NATURAL DOLOMITES IN FLUIDIZED BED

Abstract

The aim of the present investigation is to develop a model to describe the hydrodynamics, heat and mass transfers during thermal decomposition of dolomite particles in a fluidized bed. The decomposition of dolomite samples with mass from the range of 0.5-1.4 g under heat treatment has been studied in a laboratory furnace. The dissociation rate constants for magnesium and calcium components of dolomite have been determined in form of the Arrhenius equation. The obtained kinetic equations have been used in the model of fluidized bed. The model is based on the Markov chain approach and allows simulating the heat and mass transfers in fluidized bed. It contains two parallel chains of cells: one for the dolomite particles and another one for the fluidizing gas. The homologic cells of the chains can exchange heat and mass while the longitudinal the media is described by the matrices of transition probabilities. The cells for particles contain heat sources caused by the ongoing reactions. The transition matrices are associated with current physical properties of substances involved that makes the proposed model non-linear. A good agreement with the experimental data has been achieved in simulating of gas supplying, heating and decomposition of an individual particle. The modeling of the heat treatment of dolomite particles with mass 350 g under the action of fluidization was performed. One of the main features of the process influencing the bed hydrodynamics is the bed expansion with time. It occurs due to the dolomite particles settling velocity decrease during their thermal treatment. The calculating results have shown space and time non-homogeneity of the dissociation rate. The proposed mathematical model can be used as the scientific basis for operating control and design of fluidized bed reactors.Forcitation:Mitrofanov A.V., Mizonov V.E., Vasilevich S.V., Malko M.V. Experiment-calculating study of thermal decomposition of natural dolomites in fluidized bed. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 93-99