Preliminary Experimental Investigation of the Effects of Particulate Deposition on IGCC Turbine Film-Cooling in a High-Pressure Combustion Facility

Researchers at West Virginia University are working with the U.S. Department of Energy, National Energy Technology Laboratory (NETL) to study the effects of particulate deposition on turbine film cooling in a high pressure and high temperature environment. To simulate deposition on the pressure side of an Integrated Gasification Combined Cycle (IGCC) turbine first stage vane, angled film-cooled test articles with thermal barrier coatings (TBC) are subjected to accelerated deposition at a pressure of approximately 4 atm and a gas temperature of 1100°C. Two different test article geometries were designed, with angles of 10° and 20° to the mainstream flow. Both geometries have straight-cooling holes oriented at a 30° angle to the hot-side surface. A high pressure seeding system was used to generate a particulate concentration of approximately 33.3 ppmw. Particle concentrations of 0.02 ppmw exist in the IGCC hot gas path. An accelerated simulation method was developed to simulate deposition that would occur in 10000 hr of engine operation. Preliminary tests were performed at 4 atm and 1100 °C to validate the deposition process. The results showed more deposition on the 20° test article than the 10° test articles; however no substantial deposition developed on either test article. A lumped mass analysis showed that the fly ash particles dropped below the theoretical sticking temperature as they approached the test article. Deposition was analyzed non-destructively through visual observation and scanning with a scanning laser microscope. Based on the initial test run results, a detailed plan was created to increase the operating temperature of the rig and allow two 3-hour tests to be performed on each of the test articles. Non-destructive testing will be used before, in between and after the runs to examine the evolution of the deposition growth. Following the final run, destructive testing will be used to examine the chemical composition of the deposits and their potential interaction with the TBC. Preliminary work will lead to a future study the would enhance the understanding of particle deposition evolution and examine the effects of deposition on film cooling by performing the tests in a high-pressure and high-temperature environment that is similar to the high-pressure combustion exhaust gas environment of the first stage region in IGCC turbines.