A study of techniques for reducing ash deposition in coal-fired gas turbines

Direct coal-fired gas turbines are potentially attractive alternatives to conventional steam cycle electric power generation because of their higher efficiencies. However, the high mineral matter content of coal creates problems with deposition, erosion, and corrosion of turbine components. Reported here is a study of methods to reduce the rate of formation of ash deposits, including a study of the effects of the addition of potential sulfur sorbents on downstream deposition problems. Methods studied involved modifying the combustion history of the coal particles in the combustor, cooling turbine components, and adding small amounts of aluminosilicate to the coal. The results show that the proper combination of these techniques can produce a two orders of magnitude reduction in the rate of ash deposit formation.