Combustion and Deposition in Coal-Fired Turbines

Combustion and deposition behavior of coal in the form of highly beneficiated coal-water mixtures (CWM) has been investigated. The solids content of the CWM fuels was typically 50 percent, with a mean coal particle size of 4 μm and an ash content of 0.8 percent (dry). Combustion efficiencies in excess of 99.5 percent based on the carbon content of the collected ash were achieved in gas turbine-type can combustors with residence times of less than 20 ms with up to 25 percent (Btu basis) supplemental fuel oil assist. Ash deposition rates on a first-stage turbine nozzle sector were measured and were found to be much lower than would have been predicted from residual petroleum fuel experience because of differences in ash chemistry, and thus, deposition mechanism.