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

The spontaneous ignition of coal stockpiles is a serious economic and safet y problem. This paper deals with oxidation and spontaneous combustion of co al piles laid in coal storage yard and the measures to avoid the heat losse s 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 sever;al measures to reduce the heat losses were tested: periodic compaction, the use of a low a ngle slope, protection of the coal stockpiled with an artificial barrier an d covering it with an ash-water slurry made with fly ash from the same powe r 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 w ay 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 determ ined. The agreement between the temperatures measured by infrared thermogra phy and thermocouples leads to the conclusion that this technique is also a very effective method to quantify heat emissions from coal piles. (C) 1999 Elsevier Science B.V. All rights reserved.