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Ever-increasing amounts of industrial and residential wastes and their environmental footprint dictates the need for effective Waste Management practices. Thermal waste processing technologies play an important role in energy recovery from the waste. Conventional and more importantly Plasma-assisted Gasification, an advanced thermal processing technology, have been introduced as promising and environmentally benign ways for energy utilization from biomass and municipal solid waste (MSW). This work aims to study the thermal technologies, which result in production of synthesis gas that is useful for heat and power generation; therefore, conventional and plasma-assisted gasification of biomass/MSW are reviewed. In addition, various economic, environmental and policy-related issues are examined in this study. From the experimental and modeling perspective, this study also reports on the work conducted to characterize the gasification process using a gasification reactor called Gasifier Experimenters Kit (GEK) level IV. Both the syngas quality and quantity have been investigated based on a variety of feedstock, such as wood charcoal, poplar and tamarack wood chips. Moreover, the composition of the gas has been analyzed using a Gas Chromatography (GC) unit and the exact concentrations of carbon monoxide, hydrogen, methane and nitrogen were measured. In this study, a thermochemical model based on the experimental setup (GEK IV) has also been developed in the AspenPlus?? environment, an established simulation tool in chemical engineering and the energy industry. This model is capable of predicting the syngas composition, the energy required for the gasification reactions. A comparative analysis involving the experimental and simulation results is presented in this study.

Thesis (M.Eng.(Chemical Engineering))--University of Pretoria, 2008. / Abstract in English. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains v, 126 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 59-69).

Thesis (Ph. D.)--Brigham Young University Dept. of Chemical Engineering, 2006. / Includes bibliographical references (p. 141-150).

This thesis presents research on the co-gasification characteristic of biomass and coal, and mathematical modelling of the co-gasification process in two main parts: i) experimental investigation and mathematical modelling of reaction kinetics of steam gasification of single char particles of pure coal, pure biomass, and blended coal and biomass; and ii) Experimental investigation and mathematical modelling of gasification characteristics of biomass, coal and their blends in pilot scale gasifiers. From the char reactivity study, the instinct difference in gasification characteristics of the two chars has been explained and reactivity of blended char can be predicted. In the pilot scale gasifier study, effects of blending ratio in feedstock and operating conditions on co-gasification of biomass and coal were investigated.

The catalytic interaction of potassium salts in the reaction of carbon with oxygen and carbon dioxide has been studied with the aim of elucidating the mechanism of the reaction. In order to achieve this the approach used has been to utilise a wide variety of physical techniques in order to identify the active species. These range from bulk in-situ techniques like X-ray diffraction and thermogravimetric analysis to surface sensitive techniques like photoelectron spectroscopy and scanning electron microscopy. Experimental apparatus was also developed that enabled thermogravimetric analysis of samples to be carried out with mass spectra analysis of gaseous products formed. These techniques enabled the behaviour of K<SUB>2</SUB>CO<SUB>3</SUB> with and without the presence of carbon to be characterised over a wide range of temperatures and under inert and reactive atmospheres. This showed that at room temperature K<SUB>2</SUB>CO<SUB>3</SUB> would readily react with the atmosphere to form hydrated carbonate as well as KHCO<SUB>3</SUB> however upon heating to above 100<SUP>o</SUP>C these phases would decompose to leave K<SUB>2</SUB>CO<SUB>3</SUB>. This phase remained upto 600<SUP>o</SUP>C where decomposition started. The decomposition products evaporated from the solids as CO<SUB>2</SUB> and K<SUB>2</SUB>O or K. The presence of K<SUB>2</SUB>CO<SUB>3</SUB> enhanced the reaction of graphite with O<SUB>2</SUB> and CO<SUB>2</SUB>. C<SUB>8</SUB>K and residually intercalated C<SUB>8</SUB>K were used as model compounds to aid the identification of the active potassium species present during gasification. This showed K intercalates and K metal to be unstable under gasification conditions and therefore played no role in the mechanism of catalytic gasification. Photoelectron spectroscopy identified C-O-K and carbon oxides to be the predominant surface species present during gasification, while scanning electron microscopy revealed that in general graphite gasification occurred along the prismatic plane, however gasification on the basal plane took place if a fine disperson of catalyst occurred in the graphite surface.

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