The ready availability of biomass in Brazil makes this type of fuel a major candidate to integrate the country's energy matrix. Although this fuel is used as a primary energy source, its use for electricity generation is still modest. On the other hand, high efficiency and power density achieved by modem gas turbine engines make them a promising option for the power generation market. Thus, this thesis has as main objective to analyse the marriage between the solid fuel, biomass in this case, and gas turbines. Two main types of power plants are studied; the biomass integrated gasification gas turbine cycle (BIGGT) and the externally fired cycle (EFGT), which for the first time is thoroughly studied for the use of biomass fuel, plus the intercooled and recuperated variants of these power plants. The results are compared with the ordinary natural gas fuelled cycle. The method involves on- and off-design point performance and exergy analysis. The economic performance and optimisation for each cycle is also explored in order to assess their feasibility. The optimisation technique adopted is the Genetic Algorithm (GA) connected to the conventional hill-climbing methodology. This merge uses the GA to identify the region of optimum values, which are then passed on to the hill-climbing algorithm. In this way the long time demanded by the GA to converge is shortened and the unreliability of the hill-climbing method in finding the global optimum is overcome. The codes developed for design-point performance analysis and optimisation, compared with a commercial package, proved reliable and robust. The tools developed for exergy analysis (on- and off-design) are also robust and flexible, with the capability of analysing and calculating the properties of mixtures made of 23 different gases. The emissions equations are sufficiently accurate for the purposes of this thesis. The relationship proposed for calculating the variable operating and maintenance costs proved to be consistent with the current knowledge. The results show that the optimised cycles are competitive with current technology in terms of cost of electricity, the EFGT being the more competitive biomass cycle, with costs of electricity (US$ 0.07/kWh) comparable with those of the natural gas fuelled power plants. The BIGGT in its turn shows a cost of electricity 29 percent higher than its natural gas and externally fired counterparts (US$0.09/kWh) counterparts. The method used to work out the best investment - the required revenue (RR) method - demonstrated that the EFGT is again comparable with the NGGT cycle, with its RR being only 7 percent higher. The BIGGT cycle shows a higher RR due to its costly gasification/cleaning system. The minimisation of the exergy destruction ratio indicates that little improvement would be achieved after the reduction of this parameter, and a penalty - an 85 percent increase in the cost of electricity - must be paid. The environmental advantage of the biomass-fuelled cycles over the natural gas cycle is clear, making these systems very promising as low emissions alternatives. Both BIGGT and EFGT cycles presented very low CQ2 emissions. Regarding NO., emissions, the EFGT cycle has the lowest rates, whereas the BIGGT has the highest.

Made available in DSpace on 2014-06-11T19:30:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-03Bitstream added on 2014-06-13T20:07:41Z : No. of bitstreams: 1 boloy_ram_me_guara.pdf: 852285 bytes, checksum: 3d68d1d5284176beefa383dfd4da2a9d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Na atualidade, estão sendo desenvolvidas diversas tecnologia que aproveitam os recursos renováveis com a finalidade de gerar energia e diminuir emissão de poluentes ao meio ambiente. Entre essas tecnologia podemos citar a gaseificação, composta de métodos de conversão da biomassa em um gás combustível pobre. Nese caso, a biomassa deve ser gaseificada e condicionada para produzir gás de síntese que pode acionar um motor de combustão interna (MCI). A utilização do processo de gaseificação integrado a um MCI é uma opção atraente para emprego em comunidades isoladas, visto que oferece a possibilidade de obter calor por recuperação (água quente) e energia elétrica no conjunto motor/gerador de forma independente. Este trabalho tem como objetivo avaliar tecnicamente, economicamente e ecologicamente um gaseificador de biomassa tipo downdraft, integrado a um sistema de geração de energia em pequeno porte, através do desenvolvimento de um software na plataforma Delphi. O estudo permite conhecer através do balanço de energia, os parâmetros energéticos envolvidos em cada volume de controle considerado no estudo (Gaseificador, Trocador de Calor, Motor de Combustão Interna). A análise econômica considera todos os custos fixos e variáveis envolvidos para a geração de eletricidade no conjunto motor/gerador de 5 kWe acionado por gás de síntese e os investimentos capitais em cada equipamento do sistema (gaseificador, conjunto motor/gerador e trocador de calor). Os cálculos permitem determinar os custos de geração de gás de síntese, água quente e eletricidade, e também a receita anual esperada. A análise ecológica consideraos fatores de emissões obtidos pela combustão do gás de síntese no MCI. Estes fatores foram comparados considerando a combustão da gasolina, do diesel e do biodiesel, permitindo analisar se o sistema de gaseificação de biomassa integrado a um MCI é ecologicamente viável. / Nowadays, as result new systems in more efficient technological versions have beem developed for minimize pollutant emissions as wood gasification. Biomass gasification consisting of conversion methods of the biomass into poor fuel gas (syngas), in this case a syngas is used in internal combustion engine (ICE) for electrical produce. The use of biomass gasification associated into ICE makes the systems attractive for used in isolated communities because allows to independently. The aim of this work is made software to allow technical, economical and ecological studies of a owndraft gasifier integratedinto ICE. The technical study allows know alls parameters involve in which considered volume control (Gasifier, Heat Exchager, ICE). The economical study allows know eletricity cost production, syngas cost production, hot water cost production and expected annual saving considering alls fix cost involve to electrical generation in ICE. The ecological study depends on the environmental impact caused by CO2 SO2 NOx and particulate material (PM) emissions. The emissions factors obtained from syngas burn in internal combustion engines is compare to emissions factors obtained from gasoline burn, biodiesel, natural gas burn and diesel burn, allowing analyze ecological feasibility of gasifier/ice system.

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Orientador: Marcio Luiz de Souza-Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-25T12:20:22Z (GMT). No. of bitstreams: 1 BernalBernal_AndresFelipe_M.pdf: 2197321 bytes, checksum: 83a11d583679d2326d584615585e97d2 (MD5) Previous issue date: 2014 / Resumo: Novos desenvolvimentos da estratégia no conceito Fuel- Slurry Integrated Gasifier / Gas Turbine (FSIG / GT) para geração de potência termoelétrica aplicada ao caso de Bagaço de Cana de Açúcar (Sugar Cane Bagasse - SCB) são apresentados. O processo FSIG / GT permite a alimentação de combustível para uma unidade de potência baseada na gaseificação utilizando bombas de lama disponíveis no mercado, evitando, assim, os típicos sistemas de silos sequenciais, também conhecidos como sistemas de alimentação em cascata. Adicionalmente, dispensa a necessidade de oxigênio puro, algumas vezes misturado com hidrocarbonetos, para promover a ignição das partículas na suspensão injetada. A suspensão de combustível é preparada com uma alta concentração de sólido na lama e bombeada para um secador, do qual as partículas sólidas são injetadas ao gaseificador. Como ambos os equipamentos operam sob pressões semelhantes, válvulas rotativas simples e parafusos de Arquimedes podem efetuar da alimentação nesta segunda etapa. O gás é submetido a uma operação de limpeza de partículas bem como a uma redução da concentração de compostos alcalinos dentro dos limites aceitáveis para injeções em turbinas a gás convencionais. A atual fase do desenvolvimento para tal processo inclui o fluxo mássico de gás injetado e o diâmetro como variáveis de otimização do secador e gaseificador de leito fluidizado. Estas melhorias permitem uma eficiência global de geração de potência que traspassa o alcançado por outras estratégias, tais como os ciclos Rankine baseados em turbinas convencionais de alta pressão de vapor, processos BIG / GT, ou ciclos combinados usando caldeiras de câmara pressurizada / Abstract: Further developments of the strategy of the Fuel-Slurry Integrated Gasifier/Gas Turbine (FSIG/GT) concept for thermoelectric power generation applied to the case of Sugar Cane Bagasse (SCB) are presented. The FSIG/GT process allows fuel feeding to a power unit based on gasification using commercially available slurry pumps, thus avoiding the usual sequential lock-hoppers, also known as cascade feeding systems. It also dispenses with the need of pure oxygen, sometimes combined with hydrocarbons, to promote ignition of particles in the injected slurry. The fuel slurry is prepared to high dry-solid content and pumped into a dryer, from which the solid particles are fed into the gasifier. Since both equipment operate under similar pressures, simple rotary valves and Archimedes¿ screws might carry the secondary feeding. The gas is cleaned to bring the particle content and size as well alkaline concentration within the acceptable limits for injections into standard gas turbines. The present phase of development for such process includes the fluidized bed dryer and gasifier mass flow inlet gas and diameter as variables for optimizations. That allowed improvements on the overall power generation efficiency that surpasses the achieved by other strategies such as conventional Rankine based high-pressure steam turbines, BIG/GT process, or combined cycles using pressurized-chamber boilers / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

Interest in the biofuels industry in South Africa is driven largely by high oil prices and a strain on energy resources and logistics. This report considers the development of the biofuels industry in its infancy in South Africa and the factors that need to be taken into account by the potential entrants into the market. It also considers the factors which will continue to affect the sustainability of the biofuels industry.A total of fifteen experts across the biofuels value chain as well as stakeholders, who are considered experts in their field, were approached directly to provide input into this research. Further information was gathered from three focus groups involving thirty five people, all of whom are involved in the evolving biofuels sector.The research has shown that out of a number of production factors and consumption factors identified, there a few key factors that can be seen to be largely influencing the further development of the biofuels industry. Similarly a few key factors which will influence the sustainability of the biofuels industry have been identified. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

The Swartkops and Missionvale salinas in Port Elizabeth on the east coast of South Africa are surrounding by large informal settlements. The runoff from these settlements contributes largely to the eutrophication of the solar saltworks which in turn has an effect on the biotic functioning of the systems, ultimately affecting the quantity and quality of the salt produced. Inorganic nutrients and organic composition, as well as important biological groups were examined within the brine with the aim of comparing the current condition of the same salinas to their condition twelve years ago. Comparisons between inorganic nutrient concentrations and biological groups showed significantly higher inorganic nutrients, with chlorophyll a concentrations in the Swartkops salina in 2011 being significantly higher than in 2012 and the 1999 and 2011 chlorophyll a concentrations being significantly higher than 2012 in the Missionvale salina. Microalgae found in the salinas were cultured in four different growth media. Cells were stained with Nile Red fluorescent dye in order to estimate the extent of lipids production. Five of the most promising lipid producing species were isolated into a monoculture and grown at different salinities to establish the growth and lipid production in response to salinity. Halamphora coffeaeformis and Navicula sp. were found to be the best candidate species. They grew best at salinities between 50 and 70 psu and produced lipid vesicles consuming approximately 10 percent of the cell.

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In order to produce ethanol derived from lignocellulosic feeds at a cost that is competitive with current gasoline prices, the fermentation process, converting sugars to produce ethanol and the subsequent purification steps, must be enhanced. Due to their comparatively lower costs, the widespread availability across a range of climates, and their status as a dedicated energy crop, lignocellulosic biomass feeds are ideal raw materials that can be used to produce domestic fuels to partly displace our dependence on non-renewable sources. Currently, a major drawback of the technology is the relatively low ethanol tolerance of the micro-organisms used to ferment xylose and glucose. To alleviate the ethanol inhibition of Escherichia coli KO11 (ATCC 55124) during fermentation, online ethanol sequestration was achieved through the implementation of an externally located packed bed adsorber for the purpose of on-line ethanol removal (using F-600 activated carbon). By removing ethanol from the broth during the fermentation, inhibition due to the presence of ethanol could be alleviated, enhancing the substrate utilization and fermentation rate and the ethanol production of the fermentation. This study details a comprehensive adsorbent screening to identify ethanol selective materials, modelling of multi-component adsorption systems, and the design, implementation and modelling of a fermentation unit coupled with an externally located packed bed adsorber.