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Development of a model of thermal decomposition of dolomite in fluidized bed for providing sorbent systems of gas-plants

A.V. Mitrofanov

Vestnik IGEU, 2017 issue 4, pp. 56—61

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Abstract in English: 

Background: Small solid fuel power plants are gaining popularity in the energy industry. This trend is connected to the problem of obtaining an independent and reliable power supply source and also with the development of thermochemical treatment of solid fuels. At the same time, there are several limitation factors in this process. The complex power technological processing has several problems associated with exhaust gas cleaning. Calcium-based sorbents are widely used to remove sulfur dioxide and sulfur trioxide and other gaseous pollutants. Dolomite seems to be the most appropriate choice among calcium-based sorbents. That is why the development of a simple but informative model for describing the technological process of thermal decomposition of dolomitic materials now requires special attention.

Materials and methods: The Markov chain approach is used to model the complex technological processes involving thermal decomposition of dolomite particles in fluidized stage. The proposed model is complemented by the following semi-empirical sub-models: solid suspension in gas upstream, gas-solid heat transfer, solid thermal decomposition. Dolomite conversion to oxides is considered as a special one-stage process.

Results: A cell model of complex technological processes involving thermal decomposition of dolomite particles in fluidized bed is proposed. The transition matrices are associated with the current physical properties of the substances involved, which makes the proposed model nonlinear. The comparison of experimental results from the literature sources with the obtained model predictions shows a good agreement for the constant-temperature process. The obtained calculation results show the effect of decomposition enthalpy on the thermodynamic stage of fluidized bed.

Conclusions: The Markov chains model has been modified by adding independent semi-empirical sub-models of processes in fluidized bed and has been successfully used to simulate dolomite thermal decomposition. The calculations have made it clear that in order to properly describe the industrial process we should take into account the enthalpy of dolomite decomposition. The obtained mathematical model can be considered as the scientific basis for operating control and design of fluidized bed reactors.

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Ключевые слова на русском языке: 
псевдоожиженный слой, вектор состояния, матрица переходных вероятностей, скорость витания частицы, теплоотдача, массоотдача, доломит, термическое разложение, твердое топливо
Ключевые слова на английском языке: 
fluidized bed, state vector, matrix of transition probabilities, particle settling velocity, heat transfer, mass transfer, dolomite, thermal decomposition, solid fuel
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