71MWe PFBC demonstration plant was successfully operated in the period of 1992 to 1997 in EPDC Wakamatsu Work to complete all the tests of phase I. During the operation, emissions of NOx and N2O ware continuously measured under different load condition and different type of coal and their mixture. Such operational conditions influenced operational parameters such as temperatures of combustion and exhaust gas, pressure in the boiler and oxygen content in the exhaust gas, etc. The effect of such operational parameters on emissions of NOx and N2O was analyzed. Since the nitrogen in the fuel was found to be the sole source of NOx and N2O, the emissions of NOx and N2O were normalized by fuel-N to calculate conversion. The effect of operational parameters on conversion of NOx, that to N2O and overall conversion of N into nitrogen oxides (NOx +2N2O) were analyzed. This overall conversion as well as the conversion into N2O was well correlated to the temperature of cyclone gas (Tc) and square root of PO2 in the exhaust gas. The conversion into NOx was calculated as the difference of overall and N2O conversions. The concentrations of NOx and N2O are thus estimated by use of functions of Tc and PO2 named ASHTR. Parameters in the functions were experimentally defined using a coal to establish ASHTR equations. The equations were confirmed to be applied for other coals and their blends and to estimate the rapid change of NOx concentration due to the rapid change of PO2 and Tc
Recent plant materials, peat and coals were compressed and thermally treated at various temperatures (200-400°C) for 25 hours. The compaction pyrolysis products were observed with a microscope in both reflected and fluorescent lights, and their vitrinite reflectance (Ro) were also measured. The Ro values of the original samples varied from 0.1 of peat to 0.7 of Miike bituminous coal. After the thermal treatment at 300, 350 and 400°C, the Ro values increased to 0.7-1.0, 1.2-1.4 and 1.7-2.1, respectively, in spite of the kind of the original material. The compaction pyrolysis products obtained from plant materials at 200°C showed specific textures which are often observed in natural low rank coals. Those textures became homogeneous with the increasing temperatures of the thermal treatment. Petrographic characteristice of the xylems of Morwell coal and red pine changed similarly during the thermal treatment. Because peat and humus soil contained a large amount of mineral matter, they provided the pyrolysis products with different textures from other materials. The fluorescent material of leaf (metasequoia) after the thermal treatment at 200°C was considered as cutinite, and it started to melt around 250°C and disappeared around 300°C, whereas thet of Miike bituminous coal did not melt and disappear even around 300°C. There still remain quite a few coal macerals of which origin and formation are unclear, and the artificial maturation followed by the microscopic investigation is one of effective approaches to elucidate them.