Thesis (M.E.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 132-135). Also available via the World Wide Web.

Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2005. / Jones, Christopher, Committee Member ; White, David, Committee Member ; Teja, Amyn, Committee Member ; Realff, Matthew, Committee Chair. Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xx, 148 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 136-141).

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Realff, Matthew; Committee Member: DeMartini, Nikolai; Committee Member: Muzzy, John; Committee Member: Sievers, Carsten.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (M.S)--Ohio University, March, 2005. / Includes bibliographical references (p. 132-134)

Thesis (M.S)--Ohio University, March, 2005. / Title from PDF t.p. Includes bibliographical references (p. 132-134)

The poultry industry in Europe is vast and proper waste management is required in order to comply with environmental regulations. As a result, poultry litter represents a potential fuel candidate for thermal conversion technologies since it is an available source. Therefore, a process for the gasification of poultry litter is examined in this study. This process integrates a fluidised bed gasifier with a gas turbine with the aim of generating combustibles gases for energy production. This resulted in a viable solution for a small scale system to be installed on-site the biomass source. The system allows the treatment of waste with the additional benefit of generation of energy, and is suitable for a poultry farm to avoid the transportation of litter to centralised plants. Among the by-products generated during gasification, such as NOx, SO2, and fly ash, tar is a major issue when implementing this technology because tar can cause operational problems as a result of the possible formation of aerosols and soot formation due to repolymerization. A process simulation using Aspen Plus was used to evaluate four levels of integration. The equilibrium model was applied to evaluate integration schemes involving recuperation of energy from the gas turbine exhaust gases. The recuperation of residual heat to preheat air and product gases was performed with the aim of achieving the highest electrical efficiency. For the conventional "atmospheric layout", the fuel gases have to be cooled down before being compressed to the desire pressure, which causes to waste energy from the hot fuel gases. The benefit of the "pressurised layout" is that all process stages can be maintained hot. Process efficiency analyses showed that even when the "atmospheric layout" was set with energy recuperation, the "pressurised layout" delivered higher efficiencies with or without the energy recuperation into the gasifier. After a bibliographic review, the lignin content of biomass was concluded responsible for tar formation because of its aromatic nature. As lignin components, guaiacol, vanillin and catechol were chosen as tar precursors due to its presence in lignin structure. A reaction mechanism and its corresponding kinetics were derived. This mechanism was based on the three-lignin unit decomposition into lighter molecules and greater aromatic rings. Some of the tar products were involved in combustion and/or steam gasification reactions. The tar reaction mechanism was introduced into the kinetic model for the gasification of poultry litter. The results showed agreement with experimental work from previous reports for the evolution of primary tars. However, the model overestimated the total tar concentration. When the model was compared with the equilibrium model, the trends of the main product gases agreed as the air:fuel ratio was varied.

>Magister Scientiae - MSc / Energy production from coal comes with an environmental cost because of the toxic waste produced during coal combustion such as coal ash and brine which are potential water and soil pollutants. Coal ash and brine contain toxic elements which can leach and contaminate soils and ground water if not properly disposed. This study investigated the mobility of species in coal fly ash co-disposed with brine at Sasol Secunda power station in order to establish if the ash dam could act as a salt sink. The ash was dumped as a slurry with 5:1 brine/ash ratio and the dam was in operation for 20 years. It was hypothesized that the disposed Secunda fly ash was capable of leaching toxic metal elements into the surrounding soils and ground water and therefore could not be used as a long term sustainable salt sink. Weathered fly ash samples were collected along a 51 m depth core at the Secunda ash dam by drilling and sampling the ash at 1.5 m depth intervals. A fresh fly ash sample was collected from the hoppers in the ash collection system at the power station. Characterization of both Secunda fresh ash and Secunda weathered ash core samples was done using X-ray diffraction (XRD) for mineralogy, X-ray fluorescence (XRF) for chemical composition and scanning electron microscopy (SEM) for morphology. Analysis of extracted pore water and moisture content determination of Secunda fresh ash and Secunda weathered ash core samples was done in order to evaluate the physico-chemical properties of the fly ash. The chemical partitioning and mobility of metal species in the ash dam was evaluated using the sequential extraction procedure. The XRD spectra revealed quartz, mullite and calcite as the dominant mineral phases in the weathered Secunda ash core samples while Secunda fresh ash contained quartz, mullite and lime. The major oxides identified by XRF analysis for both Secunda fresh ash and Secunda weathered ash include: SiO₂, Al₂O₃, CaO, Fe₂O₃, MgO, Na₂O, TiO₂ and K₂O. The minor oxides identified for both Secunda fresh ash and Secunda weathered ash were P₂O₅, SO₃ and MnO. The trace elements identified for both Secunda fresh ash and Secunda weathered ash were As, Ba, Ce, Co, Nb, Ni, Pb, Rb, Sr, V, Y, Zr and Th. However, U was detected in some of the Secunda weathered ash samples but not in Secunda fresh ash. Both Secunda fresh ash and Secunda weathered ash was classified as class F based on the sum of the oxides of silicon, aluminium and iron by mass and the CaO content as reported by XRF analysis, and further classified as sialic and ferrocalsialic type highlighting the significant levels of Si, Al, Ca and Fe in the fly ash based on XRF analysis. The XRF analysis further showed that brine codisposal on the ash may have been responsible for the slight enrichment of some species such as Na, SO₄²⁻, Mg, K and V in the disposed Secunda weathered fly ash. However, there was no significant accumulation of these species in the disposed fly ash despite continuous addition of an estimated 117.65 billion litres of brine over the 20 year period that the dam existed. Furthermore, Secunda ash dam showed an overall total salt capture capacity of only -0.01 weight %, a strong indication that the ash dam was incapable of holding salts and would release elements to the environment over time. The scanning electron microscopy (SEM) analysis revealed spherical particles with smooth outer surfaces for Secunda fresh ash while Secunda ash core samples consisted of agglomerated, irregular particles appearing to be encrusted, etched and corroded showing that weathering and leaching had occurred in the ash dam. A decrease in pH, electrical conductivity (EC) and total dissolved solids (TDS) was observed in Secunda ash core samples compared to Secunda fresh ash. While Secunda fresh ash (n = 3) had a pH of 12.38 ± 0.15, EC value of 4.98 ± 0.03 mS/cm and TDS value of 2.68 ± 0.03 g/L, the pH of Secunda ash core (n = 35) was 10.04 ± 0.50, the EC value was 1.08 ± 0.14 mS/cm and the TDS value was 0.64 ± 0.08 g/L. The lower pH in the ash dam created an environment conducive to the release of species through leaching, while the lower EC and TDS in the ash dam implied the loss of ionic species from the ash which resulted from leaching. The moisture content (MC) analysis indicated that Secunda ash dam was very damp with an average MC of 54.2 ± 12.66 % for Secunda ash core creating favourable conditions for leaching of species in the ash dam while Secunda fresh ash had MC of 1.8 ± 0.11 %. The bottom of Secunda ash dam appeared water logged which could cause slumping of the dam. The sequential extraction procedure revealed that the major and trace elements contained in both Secunda fresh fly ash and Secunda weathered fly ash could leach upon exposure to different environmental conditions. The elements showed partitioning between five geochemical phases i.e. water soluble fraction, exchangeable fraction, carbonate fraction, Fe & Mn fraction and residual fraction. The labile phases consisted of the water soluble fraction, exchangeable fraction and carbonate fraction. The % leached out in the labile phases was expressed as a fraction of each element‟s total content e.g. Si (6.15 %) meant that 6.15 % of the total amount of Si in the ash was released in the labile phases. Na was the most labile among the major elements in the ash dam while Si and Al which form the major aluminosilicate ash matrix also showed significant lability. The % leached out in the labile phases for these major elements was as follows: for Secunda fresh ash: Si (6.15 %), Al (7.84 %), Na (11.31 %); for weathered Secunda ash core samples (n = 35): Si (7.53 %), Al (8.12 %), Na (11.63 %). This study showed that the fly ash generated at Sasol Secunda power station could not be used as a long term sustainable salt sink. The wet disposal method used at Sasol Secunda power station poses a high risk of groundwater contamination due to the high liquid to solid ratio used to transport the ash for disposal, which may lead to rapid dissolution of all the soluble components in the fly ash. The large volumes of brine that pass through Secunda ash dam in the wet ash handling system present a greater environmental concern than the dry ash handling system which involves small amounts of brine entering the ash dump.

The search for technologies for sustainable development which meets the economic and environmental viability, has provided meetings, and conferences among all nations. Clean energy production and environmental preservation are growing issues and promoted these events worldwide. On the world stage of evolution predicts energy supply that is gradually increasing and the share of biofuels (both ethanol and biodiesel) in the energy world, notably: (i) growth in the production of coal to liquid (CTL, English coal to liquid), (ii) increased demand for unconventional transportation technologies (hybrid and flex fuel cars), and (iii) increased capacity and nuclear power generation and accelerated improvements in energy efficiency. Currently, the use of the potential energy contained in organic materials such as agricultural waste, industrial and urban are still below the potential energy that exists in these inputs. Gasification is a thermochemical process for converting biomass into a gas fuel with basic features. This technology allows and the use of combined cycle with integrated gasification (IGCC), ie, the use of gases produced in gasification Otto cycle engines or gas turbine to produce electricity, and the application of the technique of capture and storage carbon (Carbon Capture and Storage, CCS), which gives low emission of sulfur, offers ease of processing multiple inputs and results in different energy products and post-processable. The choice of gasifier must be in accordance with the abundant supplies in the region. The biggest challenges for the advancement of gasification technology are the high cost of technology compared to the current price of a barrel of oil and lack of skilled labor to operate the system. This thesis aimed to assembly and assessment experiences of a pilot plant for gasification, processing inputs pertaining to the region (coal and briquette sugar cane bagasse), as the results achieved and the production of synthesis gas analysis and the production of electricity. / Fundação de Amparo a Pesquisa do Estado de Alagoas / A procura por tecnologias para um desenvolvimento sustentável o qual satisfaça a viabilidade econômica e ambiental, tem proporcionado reuniões, encontros e conferências entre todas as nações. Produção de energia limpa e preservação ambiental são temas crescentes e fomentados nesses eventos em todo mundo. No cenário mundial de evolução da oferta de energia prognostica-se que seja crescente e gradual a participação de biocombustíveis (tanto etanol quanto biodiesel) na matriz energética mundial, destacando: (i) crescimento na produção de carvão para líquido (CTL, do inglês coal to liquid); (ii) aumento na demanda de tecnologias de transporte pouco convencionais (carros flex fuel e híbridos); e, (iii) aumento na capacidade e geração de energia nuclear e melhorias aceleradas em eficiência energética. Atualmente, o aproveitamento do potencial energético contido nos materiais orgânicos, tais como: resíduos agrícolas, industriais e urbanos ainda são aquém do potencial energético existente nesses insumos. A gaseificação é um processo termoquímico de conversão da biomassa em um gás com características basicamente combustíveis. Esta tecnologia permite a utilização do Ciclo Combinado com a Gaseificação Integrada (IGCC), isto é, a utilização dos gases produzidos na gaseificação em motores de Ciclo Otto ou turbina à gás para produção de energia elétrica, além da aplicação da técnica de captura e armazenamento de carbono, (Carbon Capture and Storage-CCS), que proporciona baixa emissão de enxofre, oferece facilidade em processar vários insumos e resulta em diversos produtos energéticos e pós processáveis. A escolha do tipo de gaseificador deve ser de acordo com os insumos abundante da região. Os maiores desafios para o avanço da tecnologia da gaseificação são os altos custos da tecnologia frente ao preço atual do barril de petróleo e a falta de mão de obra especializada para operação do sistema. Esta dissertação teve por objetivo a montagem e a avaliação experimental de uma planta piloto de gaseificação, processando insumos próprios da região (carvão e briquete de bagaço de cana), como resultados alcançaram a produção e análise dos gases de síntese e a produção de energia elétrica.