The exothermic processes during coal storage reduce the calorific value of the coal which in turn results in financial losses. An accurate and easy calculation of the losses may be an efficient tool to evaluate the effectiveness of the measures taken to reduce the spontaneous heating of coal and to predict the appearance of hot spots. This study was carried out with `Mezcla' coal used at Endesa power station in Andorra–Teruel (Spain). For this purpose, laboratory measurements relating to spontaneous heating properties and field measurements were carried out. Three experimental coal piles were built, a high porosity pile, a periodically compacted pile and a pile with a low angle slope in the prevailing wind direction. A method to determine the coefficient of total losses was developed and the coefficients of calorific losses and total losses were also found. Temperatures were measured by infrared thermography and by thermocouples and a good agreement between them was found. The use of a mathematical model, developed by ASINEL, allowed to calculate the heat fluxes due to spontaneous heating and a new coefficient of calorific losses, the similarity of this coefficient with the experimentally found revealed the effectiveness of this method to quantify heat emissions. The self-heating behaviour of the pile was also followed by an infrared thermographic camera which allowed the detection of heat fluxes.

The authors wish to thank ECSC (contract 7220-EA/754) and ENDESA for the financial support to carry out this research.

Peer reviewed