CHAPTER 7 - COMBUSTION OF TWO-PHASE FUELS

Abstract

This chapter provides an overview on the combustion of two-phase fuels. The development of coal–water slurries as an alternate liquid fuel is an outcome of the oil price rises. Because of the long lifetime and widespread geographical distribution, coal will be the dominant long-term fossil fuel. The major clean coal-derived liquid fuels are solvent-refined coals (SRC), coal–oil mixtures (COM) and coal–water slurries (CWS). Coal–water slurries are also referred to as coal–water mixtures (CWM) and coal–water fuel (CWF). Both coal–oil mixtures and coal–water slurries are suitable for heating and steam-raising applications generally as an alternative to heavy fuel oil although they can be used as engine fuels. The attraction of the coal–water slurry is its complete independence of an oil supply; coal–oil mixtures are effectively a means of extending oil supplies and are less economically beneficial. Coal–water slurry is simply produced by mixing pulverized coal with water together with a small amount of a surfactant and a stabilizing agent. The coal particle diameters used are generally about 100 μm or slightly less, but in micronized coal, particle sizes are of the order of microns (micrometers). The resulting liquid looks like black oil but of course to the touch it feels like water.