Applications of Crossing Point Temperature for Determining the Spontaneous Heating Characteristics of Coals

Attempts have been made to classify various Indian coals with respect to their susceptibility to spontaneous combustion based on their crossing point temperature. Over fifty Indian coals were used during this investigation and it could be concluded that crossing point temperature can be gainfully used for this purpose. In general, higher crossing point temperature signifies lower susceptibility, whereas lower crossing point temperature indicates higher susceptibility to heating. Both the crossing point temperature as well as the slope of the time-temperature curve should be taken into consideration for determining the degree of susceptibility of coals to spontaneous combustion. Coals which show low crossing point temperature and a sudden sharp rise in the slope of the time-temperature curve may be considered to be highly vulnerable to spontaneous heating. It was also observed that higher rank coals are normally less susceptible to spontaneous combustion than lower rank coals

Effect of Moisture on the Self Heating Characteristics of Coal

The critical oxidation temperature or the crossing point temperature is often used as a parameter in studying the self heating characteristics of coals. Although the mechanism of auto-oxidation is not fully understood as yet, it is known that the moisture plays a very important role in the reaction. The paper report the influence of moisture in the self heating characteristics as investigated from the changes in the critical oxidation temperature of coals. The investigation also includes the effect of humid air (i.e. at various percentages of relative humidity). It has been observed that the self heating characteristic of coal is influenced by both the sources of moisture i.e. the moisture in coal and the humidity of air. However, the moisture in coal plays a more signification role during spontaneous combustion