Freisetzung von Alkalien und Halogeniden bei der Kohleverbrennung

Pressurized pulverized coal combustion (PPCC) is a novel, coal based combined cycle process which is comparatively simple in design and which offers efficiencies of about 55%. In order to protect the gas turbine from corrosion and erosion, a gas turbine compatible flue gas has to be supplied. The current specifications of gas turbine manufacturers are particle concentrations below 3 mg/m3N with a maximum particle diameter of 3µm and a maximum concentration of alkali species of 0,01 mg/m3N. While the demands regarding particle concentration and diameter have been met, the measured alkali concentrations in the flue gas at the test plant in Dorsten are still too high. In order to develop technical measures to reduce the concentration of alkali species in the flue gas, an increased understanding of the release behaviour of alkali species and other pollutants during the combustion of coal is necessary. In this work, the influence of coal composition, temperature and pressure on the release of pollutants during coal combustion was examined. To this aim, combustion experiments were carried out in an atmospheric pressure tube furnace, a high pressure tube furnace and with a flat flame burner. The experiments were supplemented with thermodynamic calculations. High pressure mass spectrometry (HPMS) was used for the semi-quantitative analysis. In this way important insight into the influence of composition, temperature and pressure and into the release mechanisms could be gathered