Effect of CO2 and steam gasification reactions on the oxy-combustion of pulverized coal char
Effect of CO2 and steam gasification reactions on the oxy-combustion of pulverized coal char
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DOI：
10.1016/j.combustflame.2012.06.009
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发表时间：
2012-11
影响因子：
4.4
通讯作者：
E. Hecht;C. Shaddix;M. Geier;A. Molina;B. Haynes
中科院分区：
文献类型：
--
作者：
E. Hecht;C. Shaddix;M. Geier;A. Molina;B. Haynes
For oxy-combustion with flue gas recirculation, elevated levels of CO2and steam affect the heat capacity of the gas, radiant transport, and other gas transport properties. A topic of widespread speculation has concerned the effect of gasification reactions of coal char on the char burning rate. To asses the impact of these reactions on the oxy-fuel combustion of pulverized coal char, we computed the char consumption characteristics for a range of CO2and H2O reaction rate coefficients for a 100μm coal char particle reacting in environments of varying O2, H2O, and CO2concentrations using the kinetics code SKIPPY (Surface Kinetics in Porous Particles). Results indicate that gasification reactions reduce the char particle temperature significantly (because of the reaction endothermicity) and thereby reduce the rate of char oxidation and the radiant emission from burning char particles. However, the overall effect of the combined steam and CO2gasification reactions is to increase the carbon consumption rate by approximately 10% in typical oxy-fuel combustion environments. The gasification reactions have a greater influence on char combustion in oxygen-enriched environments, due to the higher char combustion temperature under these conditions. In addition, the gasification reactions have increasing influence as the gas temperature increases (for a given O2concentration) and as the particle size increases. Gasification reactions account for roughly 20% of the carbon consumption in low oxygen conditions, and for about 30% under oxygen-enriched conditions. An increase in the carbon consumption rate and a decrease in particle temperature are also evident under conventional air-blown combustion conditions when the gasification reactions are included in the model.
