Coal Combustion--Analysis and Testing
AUTHOR: Anne Carpenter and Nina Skorupska
DATE: November 1993
Historically, the first major use of coal was for combustion, and this still remains the principal market,for coal today. Over the years, many tests have been used for assessing the quality of a coal but most of the traditional tests were devised for coal carbonisation and later adapted to combustion purposes. This report reviews and assesses the application of newer techniques which do not feature in any current standards. Techniques covered are thermal gravimetric analysis, heated wire grids, pyrolysis-mass spectrometry, pyroprobes, drop tube furnaces and small-scale fluidised bed reactors. These are believed to reflect the actual combustion conditions better than the traditional methods. How these tests are used to improve the overall understanding of coal combustion is discussed, along with the problems associated with their possible standardisation.
Two methods used for burning coal in power station boilers, namely pulverised fuel and fluidised bed combustion, are covered. It is concluded that the development of one test capable of predicting the performance of a coal under all the extremely varied industrial conditions, in either pulverised fuel or fluidised bed combustion, is highly unlikely. None of the techniques, except possibly small-scale fluidised bed reactors, is individually capable of providing a comprehensive or rapid means of evaluating the combustion properties of a particular coal. The test results will probably be applied in the immediate future primarily to provide a comparative ranking of the expected combustion behaviour of a coal.