- Title
- Characterisation of selected municipal organic waste for energy conversion through gasification
- Creator
- Ngubelanga, Nolitha
- Subject
- Biomass gasification Sewage -- Purification Biomass energy Renewable energy sources
- Date
- 2016
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10353/11020
- Identifier
- vital:36682
- Description
- Biomass gasification has become a study of great interest over the years and plant biomass with cellulose, hemicellulose, and lignin found to be an ideal resource for conversion into heat and power through thermochemical processes such as gasification. The inadequate supply of the energy in the country has become critical with the national energy provider struggling to meet the energy demands of the ever growing population of South Africa. The depletion of natural resources and the unstable prices as well as the cost of transporting the fuels together with the environmental effects of burning fossil fuels are contributing factors to the energy crisis. Alternative sources of energy that are locally available, sustainable, and environmentally friendly are presently in demand as municipal organic wastes has been considered a source of renewable energy with gasification deemed one of the leading edge technologies to harness the energy. This research only studied the characteristics and kinetics of selected municipal organic waste including decaying wood, tomatoes, onions, cabbage, butternut and bones. The research did not involve the gasification process because of expenses associated with gasification processes, however, this has been considered as future studies under the conditions of available resources to carry out the actual gasification experiments. The characteristics of selected municipal organic wastes for energy conversion through gasification were actually investigated in this study and the implication of the value of each property interpreted in relation to gasification with specific reference to information available in the literature. Proximate analysis conducted on the wastes indicate that the physical properties in terms of the weight percentages of moisture, volatile matter fixed carbon and ash contents of the wastes vary considerably, especially with regards to the last three properties. The reason for this wide variation was attributed to the source of the wastes and the standard of living of the people vi in the area where the wastes were collected. However, the values obtained for these properties are within limits for the wastes to be adequately used as feedstocks in a gasification process, except for their content of ash, which was significantly high in all of the wastes for the aforementioned reasons. The ultimate analysis of the wastes as determined using the Energy Dispersive X-ray spectroscopy gave the percentage composition of the chemical elements present in the wastes, which suggest that carbon is the chief elemental constituent of the wastes. The highest carbon content of about 47% was recorded for bone due again to the reasons previously adduced. According to McKendry, 2002, the high carbon content of the wastes implies increased calorific value as well as increased gas production during gasification. A number of ash–forming elements were also found in the wastes, which included magnesium and potassium in low concentrations that does not pose any technical challenges during gasification, although their concentration may increase under high temperature gasification, which may equally result to some catalytic effect that would contribute to the overall gasification efficiency (Anukam et al., 2016). Calorific value analysis also suggests that the wastes contain reasonable amount of energy that can be converted to useful energy through gasification. Although, variation in calorific value was also noted, the highest calorific value of about 18 MJ/kg was recoded for bones, which correlates its data on the highest carbon content of all wastes. However, the data on the calorific value of the wastes suggests that the wastes are well suited for gasification by virtue of their calorific value. FTIR analysis revealed the major functional groups present in the internal structure of the wastes. The common functional groups observed were the OH group found in the band around 3600–3400cm-1 for most of the wastes; the C–H stretching band at 2970-2780 cm-1; and the C–O as well as the C–O–C observed in the region of 1740–1710 cm-1 and 1250-1220 cm-1 for all samples, respectively. Most functional group in the internal structures of gasification feedstocks function to facilitate faster vii rates of reaction and consequently faster rates of gasification that contributes to optimum efficiency under any conditions of gasification (Anukam et al., 2016). While thermogravimetric analysis established thermal parameters that are likely to have positive influence on the gasification of the wastes, kinetic investigation revealed two parameters that may also impact on the gasification of the wastes. These are activation energy and pre–exponential factor, which were found to be in good agreement with the values obtained in the literature even though variation in these parameters was noted. The values obtained for activation energy and pre–exponential factor using the Kissinger method of kinetic analysis showed a far less value for these two parameters when compared to commonly used feedstocks like wood and coal. This was a reason attributed to the chemical characteristics of the wastes, mainly their lower content of carbon compared to these two (wood and coal) commonly used fuels.
- Format
- 73 leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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UFH Department of Chemistry
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