The aim of this work was to develop a model for the iron ore sintering process with special focus on heat front propagation through the packed bed and to provide a powerful tool ("SinterSim v1.1") for the simulation of the sintering process. Special interests were paid to the sub-models of fluid flow through the packed bed, oxidation of carbon monoxide, coke combustion, melting and solidifying of the bed material and the thermal decomposition the of ore components. Base case calculations were done showing very good agreement compared to values gained in test runs of the sintering process in a sinter pot. Numerous calculations with varied parameters were carried out to evaluate the behavior of the sintering process in means of a sensitivity coefficient for the specific variation. For duration of the sintering process and height of the sintering zone the most sensitive parameters turned out to be the mean diameter of the sinter mix material, void fraction inside the packed bed, the amount of coke breeze in the bed, the humidity of the green sinter mix and the amount of Fe 2 O 3 in the ore.

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In fluidized bed combustors, the harmful pollutants NO and N 2 O are formed from fuel-nitrogen (fuel-N). The complex homogeneous and heterogeneous reaction mechanisms determine the tradeoff between N 2 , NO, and N 2 O from fuel-N conversion affected by the bed temperature, fuel characteristics, residence time, and many more factors. To obtain a better understanding of these mechanisms and to study the relative importance of homogeneous and heterogeneous catalyzed reactions, a study on the gas reactions in a laboratory-scale fluidized bed reactor was performed. NH 3 and HCN oxidation, as well as NO and N 2 O destruction, was studied simulating the conditions of devolatilization and char combustion stages. The experimentally obtained results were analyzed with a detailed chemical kinetic model considering the two-phase structure of a fluidized bed and the quenching of radicals on the solids' surface. The significance of homogeneous reactions depends on temperature and the presence of combustible gases. Heterogeneous catalyzed reactions oxidize HCN and NH 3 to N 2 and NO, while almost no N 2 O is formed. The CH 4 addition increasing the radical level enhances the NO formation in NH 3 oxidation and N 2 O formation in the case of HCN. The presence of NO increases the selectivity toward N 2 and N 2 O for HCN and NH 3 oxidation. NO and N 2 O destruction tests demonstrate that thermal reduction of NO and N 2 O is negligible under present conditions. The presence of CH 4 reduces N 2 O emissions slightly due to reduction with the H radical. However, the presence of CH 4 affects not only the formation and destruction paths of NO and N 2 O but NO also significantly influences CH 4 combustion in fluidized beds by sensitizing its oxidation.

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The pyrolysis, devolatilization and char combustion of bituminous coal and biomass (beechwood, firwood) were investigated in a laboratory-scale fluidized bed combustor by tunable diode laser spectroscopy. Individual fuel particles were suspended in the freeboard of the unit. The bed temperature was 800 ?C, the oxygen partial pressure 0 to 20 kPa (0-10 vol.%). Two Fabry Perot type tunable near infrared diode lasers were deployed for quantitative in-situ species concentration measurements. CH4 and CO were measured simultaneously during devolatilization and char combustion in-situ 10 mm above the surface of the fuel particles as well as H2O using laser spectroscopy. Sand particles were passing the probing laser beam path. Besides the resonant absorption of the laser light by CO, CH4 and H2O severe and strongly transient non-resonant attenuation by partial blocking of the beam and beam steering effects occurred. By wavelength tuning the two laser sources, species concentrations could be determined. The measured absorbances had to be corrected for the real temperature measured at the position of the probing laser beam. In addition, CO, CO2 and O2 were determined ex-situ by con ventional methods. A spatial profile inside the FBC of major species (CH4, CO, CO2, O, H, OH) was calculated using a chemical kinetics program for a single fuel particle in a plug flow reactor geometry. The results were compared to the experimental findings. Good agreement was found. Tunable diode laser spectroscopy was found to be an apt method of determining quantitative species concentrations of multiple gases in a high temperature multi phase environment.