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Co-firing of lignite with peat and white pine in a pilot scale bubbling fluidized bed air - emissions and feedstock reactivity

dc.contributor.advisorXu, C. Charles
dc.contributor.advisorGilbert, Allan
dc.contributor.authorBadour, Chadi
dc.description.abstractThe increasing awareness of the environmental impact of fossil fuels (mainly coal) combustion, which leads to high levels of CO 2 , NO x , SO 2 , mercury and particulate emissions, has motivated research for potential alternatives such as switching from fossil fuels to biomass, or co-firing of both fuels. Co-firing proved to be a promising technology for large scale use of biomass for energy production, as it makes use of the extensive infrastructure associated with the existing coal-based power systems, and requires only relatively modest additional capital investment to achieve a significant CO 2 reduction. The research objectives of the present work were to: (1) Investigate on combustion/cofiring lignite and woodwaste/peat in a 16.19 kW pilot-scale fluidized-bed combustor, and effects of fuel-blending ratios, excess air, particle size and moisture contents on CO 2 , CO, SO 2 , and NO x emissions in the combustion/co-combustion; and (2) Study the combustion reactivity of lignite, woodwaste, peat, and the blended fuels using thermogravimetric analysis (TGA). The combustion/co-combustion behaviour and kinetics of lignite, peat and woodwaste (white pine sawdust) and their blends were investigated using non-isothermal thermogravimetric analysis (TGA) technique. The TGA experiments were performed for pure fuels and compared to blended fuels with respect to their performance in air over a temperature range of 25-700 °c and at a heating rate of 20°C/min. The overall kinetic de-volatilization-combustion reactions for these fuels and their blends were evaluated using the power law model. Using the differential thermal analysis (DTA) data and applying the least square multi-linear regression method, kinetic parameters for the overall devolatilization/combustion reactions including the apparent activation energy ( E a ) , reaction order ( n ) and the pre-exponential ( A ) factor were calculated for each homogeneous fuel and the lignite-peat or lignite-pine sawdust blended fuels (50 wt%-50 wt%%). The wood waste and peat demonstrated a higher reactivity when compared to lignite. The activation energies for lignite, peat, and white pine were determined to be 124.10 kJ/mol, 83.95 kJ/mol, and 98.23 kJ/mol, respectively. Compared with the devolatilization/combustion of homogenous solid fuels, blending peat/white pine with lignite resulted in synergistic effects, enhancing the combustion reactivity of each component fuel.en_US
dc.subjectBiomass energyen_US
dc.subjectCoal-burning power plantsen_US
dc.subjectWood waste as fuelen_US
dc.titleCo-firing of lignite with peat and white pine in a pilot scale bubbling fluidized bed air - emissions and feedstock reactivityen_US
dc.typeThesisen_US of Scienceen_US : Environmentalen_US Universityen_US

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