Gas Turbine Operation Under Long Term PFB Conditions
A key issue in pressurized fluidized bed combustion (PFBC) is the durability of the gas turbine when operated on combustion gases containing coal ash, attrited sorbent bed material, and corrosive alkali compounds. The tolerance of industrial gas turbines to erosion by dust particles has been estimated based on data from a variety of sources which are reviewed briefly in this paper. It is shown, based on experimental data, that conventional cyclones can remove sufficient dust particles to meet the projected turbine erosion tolerance. In addition, advanced clean-up devices under development by the U.S. Department of Energy which would effectively remove gas turbine erosion as an issue in PFBC are described. An overview of ongoing materials work is presented which summarizes recent experimental results and assesses the suitability of existing and new turbine alloys to survive this environment. Particular attention is given to a PFB Long Term Materials Test currently in progress which will demonstrate materials corrosion resistance for exposure times up to 14,000 hr. Preliminary results from this test are discussed.