M. Tech. Civil Engineering / Rural communities in South Africa and Africa as a whole are faced with a problem of the lack of reliable, efficient, sustainable and affordable energy sources. This problem serves as a catalyst to the slow economic development of the rural communities. In order to eradicate the problem and expedite economic development, a need exists to expand energy supply from the national grid or introduce alternative clean, sustainable, environmentally friendly and affordable energy sources to rural areas. However, expanding the national grid would not be sustainable in the long term because 80% of the national grid energy in South Africa is generated from burning fossil fuels, which is neither environmentally friendly nor renewable. The aim of this study was to address the above challenge through scientific investigation of the feasibility of introducing biogas as an alternative source of energy in rural areas. The investigation was to establish a mix ratio of the three types of domestic animal waste namely cow dung, pig dung and chicken droppings, which would optimise biogas production. Biogas, which is a mixture of mainly methane and carbon dioxide gases would in turn be used for cooking. Therefore, the broad objective of the study was to optimise methane gas production through the anaerobic digestion of domestic animal waste.

Through biomass gasification, biomass can be converted at high temperature to a product gas rich in carbon monoxide, hydrogen, and methane. After cleaning and upgrading, the product gas can be converted to biofuels such as hydrogen; methanol; dimethyl ether; and synthetic diesel, gasoline, and natural gas. Particulate matter (PM) is formed as a contaminant in the gasification process, and the aim of this work was to develop and apply a method for sampling and characterization of PM in the hot product gas.   A particle measurement system consisting of a dilution probe combined in series with a bed of granular activated carbon for tar adsorption was developed, with the aim of extracting a sample of the hot product gas without changing the size distribution and composition of the PM. The mass size distribution and concentration, as well as the morphology and elementary composition, of PM in the size range 10 nm to 10 µm in the product gas from a bubbling fluidized bed (BFB) gasifier, a circulating fluidized bed (CFB) gasifier and an indirect BFB gasifier using various types of biomass as fuel were determined.   All gasifiers and fuels displayed a bimodal particle mass size distribution with a fine mode in the <0.5 µm size range and a coarse mode in the >0.5 µm size range. Compared with the mass concentration of the coarse mode the mass concentration of the fine mode was low from all gasifiers. The evaluation of the results for the fine-mode PM was complicated by condensing potassium chloride for the CFB gasifier when using miscanthus as fuel and by condensing tars for the indirect BFB gasifier when using wood C as fuel. The mass concentration of the coarse-mode PM was higher from the CFB gasifier than from the two BFB gasifiers. The coarse-mode PM from the BFB gasifier when using wood A as fuel was dominated by char. In the CFB gasifier the coarse-mode PM was mainly ash and bed material when using all fuels. The coarse-mode PM from the indirect BFB gasifier when using wood C as fuel was mainly ash.

Lignin, a byproduct of the chemical pulping can be gasified to produce fuel gas and value-added products. Two lignins, MeadWestvaco (MWV) lignin and Sigma Aldrich (SA) lignin, were studied using two different reactors. A laminar entrained flow reactor (LEFR) was used initially to determine the effect of lignin type, temperature and residence time on char yield and fixed carbon conversion during pyrolysis and gasification. During both pyrolysis and gasification, the maximum decrease in char yield took place in the initial stage of the reaction and there was little change at longer residence times. There was not much difference between pyrolysis and gasification in the residence times obtained in the LEFR. Furthermore, a thermogravimetric analyzer (TGA) was used to study the effect of lignin type on pyrolysis and gasification. The reaction rates and char yields were affected by the lignin composition. Lignin pyrolysis showed similar behavior until 600°C but only the high-ash SA lignin showed secondary pyrolysis reactions above 600°C. Carbon gasification reactions were delayed in SA lignin. Na2CO3 addition made the primary pyrolysis reaction occur at a lower rate and enhanced the rate for secondary pyrolysis reactions. Fourier Transform Infrared (FTIR) Spectroscopy results showed that the significant loss of spectral detail started at different temperatures for MWV lignin and SA lignin. Kinetic parameters obtained using differential and Coats - Redfern integral method were comparable at lower temperatures but varied at high temperatures. Na2CO3 addition decreased the activation energy of primary pyrolysis.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 322-338).

Thesis (M.S.) -- Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Wood waste, when used for gasification is commonly pressed into briquettes, especially if no uniform particle size is available. This densification reduces problems of handling, storage and transportation and improves the combustion performance because of a more uniform fuel size. Briquettes have to be mechanically strong enough to be handled. Cohesive strength is provided by residual moisture and lignin present in the wood. The lignin acts as a natural binder. However, the briquetting process becomes more complicated if one wants to add other agricultural waste products that do not necessarily contain lignin as binders,, In this study we have investigated various briquetting process parameters, such as mixing ratios of briquettes containing wood chips, grape skins and chicken litter, moisture content and press time. The aim was to determine the optimum process parameters that allow the production of briquettes, containing a blend of biomaterials that are mechanically stable to allow further handling but yield high energy content at the same time. / AFRIKAANSE OPSOMMING: Wanneer houtafval vir vergassing gebruik word en die partikelgrootte daarvan varieer, word die materiaal normaalweg in ’n brikket gedruk. Brikketvorming vergemaklik opberging, hantering en vervoer. Weens die meer uniforme grootte en vorm van die brikkette is verbranding daarvan heelwat meer doeltreffend. Brikkette moet egter meganies sterk genoeg wees om hanteer te kan word. Die kohesiewe sterkte word deur residuele vog en lignien, wat as natuurlike bindmiddel in hout aanwesig is, verskaf. Indien ander materiale soos landbouafval, wat noodwendig geen lignien bevat nie egter gebruik word, word die brikketvormingsproses meer kompleks. In hierdie ondersoek is verskeie brikketvormingsparameters evalueer. Mengverhoudings van brikkette wat houtspaanders, druiwedoppe en hoendermis bevat, asook invloed van materiaalvoggehalte en druktyd is bestudeer. Die doel was om die optimale materiaal- en prosesparameters vas te stel wanneer ’n mengsel van biomateriale gebruik word om brikkette te lewer wat meganies sterk genoeg is maar steeds die hoogste energieopbrengs lewer. / Centre for Renewable and Sustainable Energy Studies

Made available in DSpace on 2015-07-13T12:10:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-03-24. Added 1 bitstream(s) on 2015-07-13T12:24:14Z : No. of bitstreams: 1 000832562.pdf: 3624875 bytes, checksum: d21e3aeecb27b00f8db35e4b25d45d1f (MD5) / Os níveis significativamente elevados dos subprodutos disponíveis (bagaço e palha) no processamento da cana-de-açúcar oferecem um potencial atrativo para o uso de sistemas que utilizem um gaseificador de biomassa integrado a um ciclo combinado (BIG - GTCC). Neste trabalho propõe-se estudar a incorporação do processo de gaseificação de biomassa para uso em sistema de cogeração com ciclo combinado aplicado ao setor sucroalcooleiro. Foram realizados estudos energéticos, econômicos e ecológicos da incorporação do sistema BIG - GTCC como alternativa para o aumento da oferta de produção de eletricidade em uma típica indústria sucroalcooleira do Brasil. Propõe-se o suo de uma tecnologia de pré-tratamento do bagaço para superar os problemas técnicos existentes ao alimentar, de forma contínua, o reator de gaseificação de bagaço. Na análise econômica, determina-se, inicialmente, o custo de produção de gás de síntese, permitindo alocar os custos de produção de eletricidade, energia mecânica e calor de processo no sistema proposto, considerando três configurações. Na etapa final, são determinadas as emissões de poluentes, o dióxido de carbono equivalente, o indicador de poluição e a eficiência ecológica da planta utilizando o processo de gaseificação com ciclo combinado ao setor. Conclui-se que a aplicação do processo de gaseificação apenas do excedente de bagaço em fluxo de arraste com pré-tratamento de torrefação apresenta-se como a melhor das opções propostas, tanto do ponto de vista termodinâmico, como do econômico e do ecológico / The significantly elevated levels of byproducts (bagasse and trash) currently available in the sugar cane industries offer an attractive potential for the use of the BIG - GTCC in the sugar industry. This work aims to make an energetic, economic and ecological studies of the BIG -GTCC (Biomass Integrated Gasifier - Gas Turbine Combined Cycle) system incorporation in the sugar cane industry, as an alternative to increase the levels of electricity generation in this sector. A new technology for the bagasse pre-treatment is proposed in order to overcome the technical problems observed during the continuous feeding of gasifier with sugarcane bagasse as a setting for coupling the gasifier with the sugarcane mill. An energetic analysis of the proposed system was performed. The study also identified the production cost of the synthesis gas, as well as allocated the electricity, heat, and mechanical energy production cost in the proposed system, considering the three studied cases. In the final phase, the pollutant emissions, the carbon dioxide equivalent, the pollution indicator, and the ecological efficiency of the incorporation of the cogeneration process with combined cycle in the traditional Brazilian sugar industries were determined. The main result of the study was that the application of the configuration, where only the surplus bagasse of the conventional plant is gasified in an entrained flow reactor, after pretreatment of the bagasse through a torrefaction process, appears to be economically, ecologically, and technically the best of the proposed options

Made available in DSpace on 2014-12-02T11:16:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-30Bitstream added on 2014-12-02T11:21:15Z : No. of bitstreams: 1 000798880.pdf: 1604138 bytes, checksum: 0bac43d696a76f30babea284c17c75c9 (MD5) / A cogeração tem uma grande aceitação no setor sucroalcooleiro, pois o combustível empregado (bagaço ou palha de cana) é um subproduto de fabricação. Tais sistemas geram potência mecânica ou elétrica e vapor, que são utilizados no próprio processo industrial. Porém, este tipo de geração de energia no setor encontrase muito aquém de seu potencial. Uma das alternativas tecnológicas que poderá vir a melhorar a oferta de excedentes do setor sucroalcooleiro é o uso de gaseificadores de biomassa associados a ciclos combinados. Este trabalho se baseia em dados reais de uma Usina Sucroalcooleira que utiliza o processo de cogeração com turbina a vapor de condensação com duas extrações. A partir de modificações no processo da usina, foram estudados os benefícios da integração da tecnologia de gaseificação em leito fluidizado associada a ciclo combinado. Para efeito de análise da incorporação desta configuração, construiuse, inicialmente, um modelo energético dos equipamentos que compõem o sistema de cogeração, tendo como variável de decisão a quantidade de biomassa processada pela usina. Posteriormente, realizouse o estudo exergético do sistema. A partir de uma abordagem econômica dos equipamentos, foi possível realizar o estudo exergoeconômico que se baseia no Método da Análise Funcional Termoeconômica desenvolvido por Frangopoulos (1983). Foi possível avaliar a viabilidade desta tecnologia para o setor sucroalcooleiro brasileiro permitindo gerar inovações na cadeia produtiva do etanol e corroborando para o desenvolvimento do setor e para o aumento da oferta de eletricidade no país / The cogeneration has a wide acceptance in the sugarcane industry, because the fuel used (sugarcane bagasse or straw) is a byproduct of the manufacturing process. Such systems generate electrical or mechanical power and steam, which are used in the industrial process itself. However, this type of power generation is far below its potential. One of the technological alternatives which may improve the supply of surplus to the sugarcane sector is the use of biomass gasifiers associated with combined cycles. This work is based on real data from a sugar and alcohol plant that uses the process of cogeneration with condensing steam turbine with two extractions. From the plant process modifications, the benefits of integration of fluidized bed gasification technology associated with combined cycle were studied. For purposes of analysis of the incorporation of this technology, initially built up an energy model of equipment that compose the cogeneration system, having the amount of biomass processed by the plant as a decision variable. Subsequently, we carried out the study of the exergetic system. From an economic approach of the equipment, it was possible to perform the exergeticeconomic study that is based on the Thermoeconomic Functional Analysis Method developed by Frangopoulos (1983). It was possible to assess the viability of this technology for the Brazilian sugarcane sector allowing to generate innovations in the ethanol production chain and supporting the development of the sector and to increase the supply of electricity in the country

Orientador: José Luz Silveira / Coorientador: Celso Eduardo Tuna / Banca: Wendell de Queiróz Lamas / Banca: Ivonete Ávila / Resumo : A cogeração tem uma grande aceitação no setor sucroalcooleiro, pois o combustível empregado (bagaço ou palha de cana) é um subproduto de fabricação. Tais sistemas geram potência mecânica ou elétrica e vapor, que são utilizados no próprio processo industrial. Porém, este tipo de geração de energia no setor encontrase muito aquém de seu potencial. Uma das alternativas tecnológicas que poderá vir a melhorar a oferta de excedentes do setor sucroalcooleiro é o uso de gaseificadores de biomassa associados a ciclos combinados. Este trabalho se baseia em dados reais de uma Usina Sucroalcooleira que utiliza o processo de cogeração com turbina a vapor de condensação com duas extrações. A partir de modificações no processo da usina, foram estudados os benefícios da integração da tecnologia de gaseificação em leito fluidizado associada a ciclo combinado. Para efeito de análise da incorporação desta configuração, construiuse, inicialmente, um modelo energético dos equipamentos que compõem o sistema de cogeração, tendo como variável de decisão a quantidade de biomassa processada pela usina. Posteriormente, realizouse o estudo exergético do sistema. A partir de uma abordagem econômica dos equipamentos, foi possível realizar o estudo exergoeconômico que se baseia no Método da Análise Funcional Termoeconômica desenvolvido por Frangopoulos (1983). Foi possível avaliar a viabilidade desta tecnologia para o setor sucroalcooleiro brasileiro permitindo gerar inovações na cadeia produtiva do etanol e corroborando para o desenvolvimento do setor e para o aumento da oferta de eletricidade no país / Abstract: The cogeneration has a wide acceptance in the sugarcane industry, because the fuel used (sugarcane bagasse or straw) is a byproduct of the manufacturing process. Such systems generate electrical or mechanical power and steam, which are used in the industrial process itself. However, this type of power generation is far below its potential. One of the technological alternatives which may improve the supply of surplus to the sugarcane sector is the use of biomass gasifiers associated with combined cycles. This work is based on real data from a sugar and alcohol plant that uses the process of cogeneration with condensing steam turbine with two extractions. From the plant process modifications, the benefits of integration of fluidized bed gasification technology associated with combined cycle were studied. For purposes of analysis of the incorporation of this technology, initially built up an energy model of equipment that compose the cogeneration system, having the amount of biomass processed by the plant as a decision variable. Subsequently, we carried out the study of the exergetic system. From an economic approach of the equipment, it was possible to perform the exergeticeconomic study that is based on the Thermoeconomic Functional Analysis Method developed by Frangopoulos (1983). It was possible to assess the viability of this technology for the Brazilian sugarcane sector allowing to generate innovations in the ethanol production chain and supporting the development of the sector and to increase the supply of electricity in the country / Mestre

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-24Bitstream added on 2014-06-13T18:10:02Z : No. of bitstreams: 1 passolongo_r_me_ilha.pdf: 1135025 bytes, checksum: dbd8595b1dfa21765349cdeb44120185 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho analisa, sob o ponto de vista termodinâmico, termoeconômico e econômico a integração da gaseificação da biomassa em uma usina sucroalcooleira. Considera-se a gaseificação da palha e da vinhaça, com a queima do bagaço na caldeira para gerar o vapor necessário para a usina. São considerados cinco casos de estudo. Inicialmente é feita uma análise da planta atual de vapor de uma usina do oeste paulista que utiliza equipamentos modernos e eficientes, incluindo uma caldeira que produz vapor a altos níveis de pressão e temperatura, o qual é utilizado para geração de eletricidade em uma turbina de extração-condensação de múltiplos estágios e em outra turbina de contrapressão. Além disso, todos os acionamentos das moendas são eletrificados. Na sequência são definidos casos de estudo que combinam a gaseificação da vinhaça e da palha da cana com a planta atual de vapor da usina. Por fim, é definida uma planta de uma usina nova com o dobro da moagem considerada inicialmente, incluindo uma caldeira que gera vapor a altos níveis de pressão e temperatura, e uma turbina de extração-condensação de múltiplos estágios, integrando a gaseificação da palha e da vinhaça. Os resultados mostram que as plantas com gaseificação promovem um aumento substancial na geração de eletricidade da usina e na eficiência da planta. Entretanto, sob o ponto de vista termoeconômico e econômico, as plantas que integram a gaseificação apresentam maior custo de geração da eletricidade e maior tempo de retorno do investimento / In this work, the integration of biomass gasification in a sugarcane plant is analyzed from the thermodynamic, thermoeconomic and economic point of view. The gasification of straw and stillage by-products is taken into account, alongside the burning of bagasse in the boilers to generate steam for the plant. Five case studies are considered. At first, an analysis is carried out of the current steam plant from a sugarcane factory in the western region of Sao Paulo State that deploys modern and efficient equipment, including a boiler that produces steam at high pressure and temperature, which is used to generate electricity in a multistage condensation-extraction steam turbine and in a backpressure turbine. All drives of the mills are electrified. Following that, some more case studies are specified, combining the gasification of stillage and straw with the current steam plant of the sugarcane factory. Finally, a new plant is proposed, with twice the milling currently obtained, including a boiler that generates steam at higher pressure and temperature, and a multistage condensation- extraction turbine, integrating the gasification of straw and stillage. The results show that plants with gasification promote a substantial increase in electricity generation and in the efficiency of the plant. However, from the thermoeconomic and economic point of view, the plants that considers gasification presents a higher cost of the electricity and a longer payback