Investigating the combustion characteristic temperature of 28 kinds of Chinese coal in oxy-fuel conditions

• 28 kinds of Chinese coal combustion in O2/CO2 atmosphere are investigated.
• The relation between coal properties and characteristic temperature is studied.
• The oxidation regime under different O2 concentration is investigated.
• The coal with higher fixed carbon or ash is easily affected by O2 in ignition.
• The coal with lower O/C or H/C is significantly affected by O2 concentration.

Oxy-fuel combustion is widely considered to be the most promising potential CO2 capture technology. In this study, the combustion characteristic temperatures of 28 kinds of Chinese coals were investigated under three O2 concentrations of oxy-fuel through the non-isothermal thermo-gravimetric analysis. Three characteristic temperatures (ignition temperature, temperature at the maximum reactivity rate, and burnout temperature) were obtained from the experimental curve. The pulverized coal was also described through proximate analysis and ultimate analyses. The relationship between coal properties and characteristic temperature was investigated with the linear fitting method. Furthermore, the influences of coal properties on oxy-coal combustion were studied according to the close link between two slopes under different O2 concentrations. Similarly, the influences of oxidation regimes can be inferred by comparing the trends of characteristic temperature under various O2 concentrations. The mechanisms were studied in detail by analysing the carbon crystal structure and the ash element. Finally, the coal easy to be affected by O2 concentration was identified, and the main control regimes under different conditions were distinguished. The research results show important significance in the industrial application of oxy-fuel combustion technology.