THEORETICAL STUDY OF THE BATCH CIRCULATING FLUIDIZATION

DOI: 10.6060/tcct.20165911.5421
Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2016. V. 59. N 11. P. 92-99

The objective of the study is to develop a simple but informative model to estimate the particle concentration distribution and their flows in a batch circulating fluidized bed. A cell model based on the theory of Markov chains is used for that. The riser and downer of the circulating fluidized bed apparatus are presented as 1D arrays of perfectly mixed cells. The evolution of particle content in the cells is controlled by the matrixes of transition probabili-ties, which are different for the riser and downer. It is supposed that these transition proba-bilities depend on the particle content in the cells. The upper cells of the chains are connected through a gas-solid separator, which can be perfect or not, and the bottom cells are connect-ed through a valve that controls the particle flow from the downer to the riser. The key objec-tive of the numerical experiments with the model was to estimate the transient and steady-state processes in such apparatus taking into account the interference of the processes of particle fluidization in the riser and their downward motion in the downer. In some intervals of the process parameters variation the circulation loop was shown to be very sensitive to them, and in some intervals it is not. The case of time-varying settling velocity of particles was examined too, and it was shown that this variation had the large influence on the process parameters evolution.

Key words: fluidization, circulating fluidized bed, Markov’s chain, superficial velocity, particle settling velocity, state vector, transition probabilities matrix, circulation ratio

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2016, Т. 59, № 11, Стр. 92-99

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