Formation of deposits from heavy fuel oil ash in an accelerated deposition facility at temperatures up to 1219 °C

Some industrial gas turbines are currently being fired using heavy fuel oil, which contains a small percentage of inorganic material that can lead to fouling and corrosion of turbine components. Deposits of heavy fuel oil ash were created in the Turbine Accelerated Deposition Facility (TADF) at Brigham Young University under gas turbine-related conditions. Ash was produced by burning heavy fuel oil in a downward-fired combustor and collecting the ash from the exhaust stream. This ash was then introduced into the TADF and entrained in a hot gas flow that varied from 1101 °C to 1219 °C. Sulfur dioxide was introduced to the system to achieve 1.1 mol% SO2 in the exhaust to simulate SO2 levels in turbines burning heavy fuel oil. The gas and particles were accelerated to over 200 m/s before impinging on a nickel-based superalloy coupon and forming deposits. The ash deposits were collected and the capture efficiency, surface roughness, and deposit composition were measured. The deposits were then washed with deionized water, dried, and the analysis was repeated. As the gas temperature increased, there was no effect on capture efficiency and the post-wash roughness of the samples decreased. Washing aided in the removal of sulfur, magnesium, potassium, and calcium.