Date of Award
Master of Science
The purpose of this study is to characterize the heat transfer and chemical processes that occur within the reactor of an indirectly-heated biomass gasification process. As opposed to conventional gasification processes, in which combustion and pyrolysis reactions occur simultaneously within the reactor, combustion and pyrolysis reactions occur sequentially in a cyclic fashion. The key to this system is employment of a thermal energy storage system. The thermal energy system, called a thermal ballast, is composed of lithium fluoride, a phase-change material, stored within stainless steel tubes. During the combustion process, thermal energy is stored as latent heat of the phase-change material, while this energy is released during the pyrolysis process to drive the endothermic reactions. The composition of the product gases varies throughout the process, however. Previous experiments were unable to resolve these changes in composition throughout the gasification cycle. Through the use of continuous emission monitors, experiments were conducted to quantify the composition of the product gases in this study. In addition to the experiments conducted, a previous model of the gasification process was modified to account for temperature gradients that arise in the thermal ballast tubes during the phase-change process. Following the modification of the model, sensitivity analyses were performed to identify the most significant parameters of the system. Recommendations for process improvement based on these analyses have been included.
Keith Richard Cummer
Cummer, Keith Richard, "Operation and modeling of a thermally-ballasted gasification system" (2003). Retrospective Theses and Dissertations. 19937.