Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 111-114). Also available on the World Wide Web.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed October 13, 2009). PDF text: xiv, 183 p. : ill. (some col.) ; 1 Mb. UMI publication number: AAT 3358961. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (M.Sc.). / Written for the Dept. of. Bioresource Engineering. Title from title page of PDF (viewed 2007/08/30). Includes bibliographical references.

Thesis (M.S.)--University of Iowa, 2009. / Thesis supervisor: Lea-Der Chen. Includes bibliographical references (leaves 110-114).

Thesis (M.E.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (p. [85]-87, 2nd sequence). Also available via the World Wide Web.

Biomass gasification is a promising technology for conversion of various biomass feedstocks to producer gas for subsequent production of fuels and chemicals. A dual fluidised bed (DFB) steam gasifier is used in the present research to produce the producer gas for Fischer-Tropsch (FT) liquid fuel synthesis. However, NH3 and H2S gases in the producer gas remain an issue to be resolved because they are poisonous to the catalysts employed in the FT reactor. To remove NH3 and H2S, two methods were investigated in this research: (1) primary measures which were employed in the DFB steam gasifier including process optimisation and application of bed materials for catalytic NH3 decomposition and H2S adsorption; and (2) secondary measures or downstream cleaning methods after the gasifier. The combination of the primary measures and the secondary measures is an effective way to remove the NH3 and H2S in the producer gas from gasification process. Studies on the primary measures were divided into two parts. In the first part, in situ reduction of NH3 and H2S in biomass producer gas from the DFB steam gasifier was performed. The primary measures consisted of optimisation of operation conditions and application of bed materials. The main operation conditions in the DFB steam gasifier studied were gasification temperature, steam to fuel (S/F) ratio, and mean gas residence time (f). The bed materials tested include silica sand, iron sand (ilmenite), and calcined olivine sand. For the second part of the primary measures, an influence of the lignite to fuel (L/F) ratio on NH3 and H2S concentrations and conversions in co-gasification of blended lignite and wood pellets in the DFB steam gasifier was investigated. Experiments were performed in the DFB steam gasifier at 800C with blended lignite and radiata pine wood with the L/F ratio ranging from 0% to 100%. It was found that all of the studied parameters including gasification temperature, S/F ratio, f, bed material, and L/F ratio significantly influenced the NH3 and H2S concentrations and conversions in the producer gas. For the secondary measures, a novel hot catalytic reactor and adsorber was developed in the present research for the simultaneous removal of NH3 and H2S. In a hot gas reactor operated at 500-800C and under atmospheric pressure, titanomagnetite was tested for NH3 and H2S removal by hot catalytic NH3 decomposition and H2S adsorption reactions. Titanomagnetite was tested with three different gas streams including 2,000 ppmv NH3 in Ar, 2,000 ppmv NH3 and 230 ppmv H2S in Ar, and 2,000 ppmv NH3 and 230 ppmv H2S in simulated biomass producer gas. From the experimental results, it was discovered that ferrite (α-Fe) readily formed by the H2 reduction of titanomagnetite has shown almost complete NH3 decomposition (100%) in Ar gas at 700 and 800C. The presence of H2S in the gas mixture of NH3 and Ar slightly reduced the catalytic activity for NH3 decomposition at 700 and 800C (>96%) and H2S adsorption of more than 98% could be achieved at the same temperature range. However, in the test with simulated biomass producer gas, 60% NH3 decomposition and 9% H2S adsorption were obtained at 800C, whereas 40% NH3 decomposition and 80% H2S adsorption were obtained at 500C. The decrease of NH3 decomposition and H2S adsorption at 800C in simulated biomass producer gas could be due to the high content of H2 (45 vol%) in the feed gas that favours the reverse reactions of NH3 decomposition and H2S adsorption, the increased surface coverage of the active α-Fe phase by adsorbed hydrogen, and the competition of α-Fe for the reverse water-gas shift reaction. Besides, it was discovered that the temperature significantly affected the removal of NH3 and H2S in simulated biomass producer gas and thus it needs to be optimised.

Biomass gasification is a technology under development that presents a means of generating hydrogen using renewable energy. While many forms of gasification have been investigated, steam gasification using a dual fluidised bed (DFB) reactor has been shown to efficiently produce high hydrogen content producer gas. The aims of this research were to increase the hydrogen yield from the 100kW DFB gasifier installed at the University of Canterbury, and thereby improve the current state of the art of gasifier operation. Calcium carbonate-based minerals such as calcite and dolomite were shown to be able to improve hydrogen production by absorbing carbon dioxide in the producer gas, promoting the water gas shift reaction. Bed material mixtures of olivine and calcite were the most effective at improving gasifier performance, increasing producer gas yield by 20%, increasing cold gas efficiency by 6% and increasing hydrogen yield by 85%. In addition, the carbon monoxide content was reduced and the ratio of hydrogen to carbon monoxide in the producer gas was ideal for Fisher-Tropsch synthesis of liquid fuels.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains vi, 184 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 82-84).

Thesis (Ph.D.) in Chemical Enigneering--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 189-193).

Esta tesis desarrolla un modelo sencillo pero riguroso de plantas de trigeneración con gasificación de biomasa para su simulación, diseño y evaluación preliminar. Incluye una revisión y estudio de diferentes modelos propuestos para el proceso de gasificación de biomasa.Desarrolla un modelo modificado de equilibrio termodinámico para su aplicación a procesos reales que no alcanzan el equilibrio así comodos modelos de redes neuronales basados en datos experimentales publicados: uno para gasificadores BFB y otro para gasificadores CFB. Ambos modelos, ofrecen la oportunidad de evaluar la influencia de las variaciones de la biomasa y las condiciones de operación en la calidad del gas producido. Estos modelos se integran en el modelo de la planta de trigeneración con gasificación de biomasa de pequeña-mediana escala y se proponen tres configuraciones para la generación de electricidad, frío y calor. Estas configuraciones se aplican a la planta de poligeneración ST-2 prevista en Cerdanyola del Vallés. / This thesis develops a simple but rigorous model for simulation, design and preliminary evaluation of trigeneration plants based on biomass gasification. It includes a review and study of various models proposed for the biomass gasification process and different plant configurations. A modified thermodynamic equilibrium model is developed for application to real processes that do not reach equilibrium. In addition, two artificial neural network models, based on experimental published data, are also developed: one for BFB gasifiers and one for CFB gasifiers. Both models offer the opportunity to evaluate the influence of variations of biomass and operating conditions on the quality of gas produced. The different models are integrated into the global model of a small-medium scale biomass gasification trigeneration plant proposing three different configurations for the generation of electricity, heat and cold. These configurations are applied to a case study of the ST-2 polygeneration plant foreseen inCerdanyola del Valles.