Coal water

Coal-water slurry fuel is a combustible mixture of fine coal particles suspended in water. It can be used to power boilers, gas turbines, diesel engines and heating and power stations. Coal-water slurry fuel is a combustible mixture of fine coal particles suspended in water. It can be used to power boilers, gas turbines, diesel engines and heating and power stations. A coal-water slurry fuel is defined by a number of factors including its viscosity, particle size, rate of sedimentation, ignition temperature (800–850 °C ), combustion temperature (950–1,150 °C ), ash content and calorific value (3700–4700 kcal/kg). When coal-water slurry fuel combusts, over ninety-nine percent of its carbon content is consumed. Coal-water slurry fuel is fire-proof and explosion-proof. Ash content of less than ten percent is desirable for boilers. For diesel engines, there is no limit. The production of coal-water slurry fuel involves the crushing of coal or coal sludge to particles between 10 and 65 micrometers diameter (standard crushers can be used); wet milling and homogenisation (with additives as required). The resulting product (coal slurry) is then prepared for intermediate storage or transport. Large particle coal-water slurry fuel can be used to produce steam in boilers. Smaller (under 80 micrometer) particle coal-water slurry fuel can be used in diesel engines with or without co-fuels. For example, low speed marine or modular power plant diesels can operate on pure coal-water slurry fuel whereas medium speed diesels such as locomotive engines may need diesel as a co-fuel which will act as an ignition source. Very small (5 to 10 micrometer) particle coal-water slurry fuel has been trialled in combined cycle gas turbine power plants. Smaller sized particles are more versatile in use but are more difficult to produce.