ANALYSIS OF EFFICIENCY OF PULVERIZED COAL GASIFICATION IN HIGH-TEMPERATURE FLOW OF O2/N2 AND O2/CO2 USING MATHEMATICAL MODELING

The relevance of the study is associated with growing issues of regulating carbon emissions of solid fuel combustion and increasing environmental requirements for heat power plants. The aims of the study are investigation of CO2 recycling prospects at coal-fired power plants with internal gasification using mathematical modeling based on an analysis of the fuel conversion processes efficiency, determination of the coal processing optimal modes and evaluation of possibility of implementing these modes from the point of view of technological limitations. Object of the study is pulverized coal gasification in the atmospheres with different composition and initial temperature. Research method: mathematical modeling of the process of pulverized coal thermochemical conversion in one-dimensional stationary statement. Results. The author has plotted the calculated dependences of gasification characteristics (cold gas efficiency, temperature of the produced gas) on the specific flow rate of the gasification agent (alpha=0,1-0,7), oxygen concentration (20-30 %) and the initial temperature (373-1373 K) for O-2/N-2 and O-2/CO2 mixtures. The optimal values of specific flow rates and the maximum values of cold gas efficiency in the entire range of parameters are determined. The author estimated the contribution of the thermophysical properties and gas reactivity to the change in the cold gas efficiency of the process when changing the composition of the gasification agent. To study the efficiency of heating oxidizer, the author used the criterion that takes into account heat external supply. The analysis shows that air overheating does not give a positive effect on composition of gasification products due to the strict stoichiometric restrictions; overheating of carbon dioxide allows not only increasing cold gas efficiency, but also improving process stability at low values of specific oxidizer consumption.