Prevention of spontaneous combustion in coal stockpiles. Experimental results in coal storage yard

Abstract

The spontaneous ignition of coal stockpiles is a serious economic and safety problem. This paper deals with oxidation and spontaneous combustion of coal piles laid in coal storage yard and the measures to avoid the heat losses produced. Investigations on self heating were carried out with five test piles 2000–3000 tons. built at the ENDESA power station in Teruel Spain., and the results are here reported. The efficiency of several measures to reduce the heat losses were tested: periodic compaction, the use of a low angle slope, protection of the coal stockpiled with an artificial barrier and covering it with an ash–water slurry made with fly ash from the same power station. Wind tunnel tests were used to design the wind barrier which was showed to be very effective although the results indicated that the best way to avoid the heat losses is the use of an ash–water slurry to cover the coal pile. A direct method to determine the coefficient of total losses was developed and the coefficients of heat losses and total losses were determined. The agreement between the temperatures measured by infrared thermography and thermocouples leads to the conclusion that this technique is also a very effective method to quantify heat emissions from coal piles.