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Advisor(s)
Abstract(s)
No sentido de aumentar o aprovisionamento energético e diminuir a dependência de combustíveis fósseis, a procura de novas energias com impacto reduzido para o ambiente é uma temática cada vez mais importante e urgente. É nesta vertente que a valorização energética de resíduos por gasificação se apresenta como uma das alternativas às energias tradicionais, produzindo um gás de produção rico em hidrogénio. O objetivo principal do trabalho consistiu no estudo da viabilidade técnica da gasificação de gordura animal, que é um resíduo da indústria dos curtumes depositado, atualmente, em aterro. Foi avaliado o efeito da variação do caudal (1,2 g/min, 1,7 g/min, 2,3 g/min e 2,9 g/min), da temperatura (750 ºC, 850 ºC, 900 ºC e 950 ºC), da razão água/gordura da mistura na alimentação (50/50, 60/40 e 75/25 % m/m) e do agente de gasificação (vapor e misturas de vapor/O2) na composição do gás de produção obtido e nos parâmetros de gasificação que avaliam o desempenho do processo (eficiência de conversão de carbono, eficiência de conversão de hidrogénio, rendimento do gás seco, poder calorífico do gás de produção e eficiência do gás frio). Para o efeito, utilizou-se um reator de gasificação de leito fixo em aço inox com uma altura de 0,571 m e um diâmetro
interno de 0,054 m, contendo como leito partículas de alumina. O estudo da gasificação da gordura animal permitiu perceber que, o aumento do caudal de alimentação resulta numa redução nos valores obtidos para os parâmetros de gasificação da gordura, indicando uma diminuição no desempenho do processo de gasificação. Valores superiores dos parâmetros de gasificação foram obtidos para temperaturas mais elevadas, devido ao elevado rendimento de produção de fase gasosa nestas temperaturas. O aumento da temperatura de operação resultou num aumento da concentração de H2 no gás de produção, observando-se ainda uma diminuição do poder calorífico superior do gás. O estudo do efeito da razão de mistura água/gordura nos parâmetros de gasificação permitiu depreender que, o aumento do teor de água na mistura resulta num aumento, previsível, da concentração de H2 no gás de produção. O valor do poder calorífico superior diminui com o aumento da razão de mistura de 50/50 para 60/40, mantendo-se, posteriormente constante. A eficiência de conversão de hidrogénio aumentou com o aumento da razão água/gordura e relativamente aos restantes parâmetros de gasificação, o aumento do teor de água não alterou significativamente os resultados obtidos. Por fim, o estudo preliminar da gasificação com uma mistura vapor/O2 como agente oxidante não promoveu uma melhoria significativa dos parâmetros de gasificação, diminuindo ligeiramente a concentração de hidrogénio no gás de produção.
To increase energy supply and reduce dependence on fossil fuels, the search for new energy with reduced impact on the environment is an increasingly important and urgent topic. It is in this aspect that the energy recovery of waste through gasification presents itself as one of the alternatives to traditional energy, producing a producer gas rich in hydrogen. The main objective of the work was to study the technical feasibility of gasification process of animal fat, which is a waste from the tanning industry currently deposited in landfill. Is was evaluated the effect of flow rate (1.2 g/min, 1.7 g/min, 2.3 g/min and 2.9 g/min), temperature (750 ºC, 850 ºC, 900 ºC and 950 ºC), the water/fat ratio of the mixture in the feed (50/50, 60/40 and 75/25% m/m) and the gasification agent used (steam and vapor/O2 mixtures) in the composition of the obtained producer gas and in the gasification parameters that assess the performance of the process (carbon conversion efficiency, hydrogen conversion efficiency, dry gas yield, higher heating value of the producer gas and cold gas efficiency). For this purpose, it was used a fixed bed gasification reactor in stainless steel, with a height of 0,571 m and an internal diameter of 0,054 m, containing alumina particles as a bed material. The study of animal fat gasification allowed to understand that the increase in the feed flow rate results in a reduction in the values obtained for the fat gasification parameters, indicating a decrease in the performance of the gasification process. Higher values of the gasification parameters were obtained for higher temperatures, due to the high gas phase yield at these temperatures. The increase in operating temperature resulted in an increase in the concentration of H2 in the producer gas, and in a decrease in the higher heating value of the gas. The study of the effect of water/fat ratio on the gasification parameters allowed to conclude that the increase in the water content in the mixture results in an increase in the concentration of H2 in the producer gas. The value of the higher heating value decreases as the water/fat ratio increases from 50/50 to 60/40, remaining constant thereafter. The hydrogen conversion efficiency increased with the increase in the water/fat ratio and in relation to the remaining gasification parameters, the increase in water content did not significantly change the results obtained. Finally, the preliminary study of gasification using as gasification agent a steam/O2 mixture did not promote a significant improvement in gasification parameters, slightly reducing the hydrogen concentration in the producer gas.
To increase energy supply and reduce dependence on fossil fuels, the search for new energy with reduced impact on the environment is an increasingly important and urgent topic. It is in this aspect that the energy recovery of waste through gasification presents itself as one of the alternatives to traditional energy, producing a producer gas rich in hydrogen. The main objective of the work was to study the technical feasibility of gasification process of animal fat, which is a waste from the tanning industry currently deposited in landfill. Is was evaluated the effect of flow rate (1.2 g/min, 1.7 g/min, 2.3 g/min and 2.9 g/min), temperature (750 ºC, 850 ºC, 900 ºC and 950 ºC), the water/fat ratio of the mixture in the feed (50/50, 60/40 and 75/25% m/m) and the gasification agent used (steam and vapor/O2 mixtures) in the composition of the obtained producer gas and in the gasification parameters that assess the performance of the process (carbon conversion efficiency, hydrogen conversion efficiency, dry gas yield, higher heating value of the producer gas and cold gas efficiency). For this purpose, it was used a fixed bed gasification reactor in stainless steel, with a height of 0,571 m and an internal diameter of 0,054 m, containing alumina particles as a bed material. The study of animal fat gasification allowed to understand that the increase in the feed flow rate results in a reduction in the values obtained for the fat gasification parameters, indicating a decrease in the performance of the gasification process. Higher values of the gasification parameters were obtained for higher temperatures, due to the high gas phase yield at these temperatures. The increase in operating temperature resulted in an increase in the concentration of H2 in the producer gas, and in a decrease in the higher heating value of the gas. The study of the effect of water/fat ratio on the gasification parameters allowed to conclude that the increase in the water content in the mixture results in an increase in the concentration of H2 in the producer gas. The value of the higher heating value decreases as the water/fat ratio increases from 50/50 to 60/40, remaining constant thereafter. The hydrogen conversion efficiency increased with the increase in the water/fat ratio and in relation to the remaining gasification parameters, the increase in water content did not significantly change the results obtained. Finally, the preliminary study of gasification using as gasification agent a steam/O2 mixture did not promote a significant improvement in gasification parameters, slightly reducing the hydrogen concentration in the producer gas.
Description
Keywords
Gasification Animal fat Producer gas Steam Oxygen Gasificação Gordura animal Gás de produção Vapor Oxigénio