TESTS OF A HEAT EXCHANGER FOR INDIRECTLY FIRED COMBINED CYCLES WHILE FIRING COAL-BIOMASS BLENDS

摘要

Bench- and pilot-scale tests of a high-temperature heat exchanger to produce pressurized air for an indirectly fired combined-cycle (IFCC) power plant were performed while firing three coal-biomass blends. The work was performed at the University of North Dakota Energy & Environmental Research Center under a joint Xcel Energy-U.S. Department of Energy project. An IFCC using this type of heat exchanger (FIX) has the potential to reach efficiencies of 45% when firing coal and over 50% when supplemental natural gas is fired into the gas turbine. In this paper, we describe results from combined coal-biomass-fired tests of an oxide dispersion-strengthened FIX operating at maximum surface temperature of 1050℃ (1920℉). The tests were performed in a pilot-scale slagging combustion system while firing three coal-biomass blends in air. The biomasses, consisting of hog fuel, switchgrass, and corn stover, were added at a rate of 20% of the energy input to the system. In addition, we describe bench-scale determinations of the mechanisms of corrosion of the alloys cooled to 1050° and 1150℃ (1920° and 2100℉) while exposed to the flowing biomass-coal slags at 1500℃ (2730℉).