The emissions of pollutants from power plants have become the subject of increasing public concern. Legislation limiting the amount of emitted pollutants has made control of pollutants such SOx, NOx, CO, and particulates a major concern in designing and operating coal fired power plants. Another important environmental issue addressed here is the recent surge in landfill closure. Environmental concern, cost, and availability of new land are major causes for the recent escalation of landfill costs. An alternative to the waste disposal in landfill is the solid waste incineration. Disposal of solid waste through incineration, while offering numerous advantages, produces numerous pollutants. Operating and initial costs associated with the control of these emissions are high. As a result of both engineering and regulatory concerns, researchers are looking for combustion processes with higher efficiency and improved pollutant control. Fluidized Bed Combustion (FBC), which utilizes the phenomenon of fluidization for the purpose of more efficient combustion, has shown the potential to meet these demands at lower costs. FBC is studied in this thesis for the possible reduction of air emissions from coal and solid waste combustion.
The evaluation of design, development of a fluidized bed combustor, the analysis of the fluidizing phenomena, and the combustion process for an unspecified fuel are discussed in this work. In general, the fuel must be fed into a heated bed for combustion. The entrained particles need to be separated from the exhaust gas and unburned particles have to be returned to the bed for complete combustion. The whole system must be integrated to perform the desired operations. However, the prediction of the particle's behavior, the rates of mass and heat transfer, combustion reactions, and distribution of fuel and sorbent within the bed is difficult to predict accurately. Therefore, the design process requires the modeling of the bed in finding the key design parameters. Analytical models are needed to simulate the behavior of the bed in the desired operating conditions and be solved by computer codes to find the design parameters. An acrylic prototype model is also needed to verify analytical data. Agreement between experimental data and analytical predictions would indicate that the corresponding data would be suitable for design. Actual construction and equipment specifications necessary to meet constraints, both engineering and economic, are also needed to complete the design description.