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Abstract(s)
Os combustíveis fósseis são, desde a revolução industrial, as fontes energéticas mais utilizadas a nível mundial. Contudo, com o desenvolvimento tecnológico vieram as preocupações com questões ambientais, nomeadamente com as emissões de gases de efeitos de estufa resultantes dos processos onde se utilizam este tipo de combustíveis. De modo a ultrapassar esta questão, os países têm vindo a apostar na utilização de energias renováveis como substitutos dos combustíveis fósseis. Das fontes energéticas disponíveis, a biomassa tem revelado um enorme potencial devido às reservas existentes a nível mundial, e por ser um recurso bastante flexível podendo ser convertida diretamente em energia sob a forma de calor ou eletricidade ou, em biocombustíveis. A produção de gás de síntese, requer um suporte versátil de energia renovável (p. ex., Solar, Eólica, Biomassa), já que a partir deste gás, podem ser produzidos biocombustíveis sintéticos, como, por exemplo, biometano (principal componente do biogás), biometanol, Bio-DME, etc. Este trabalho de I&DT tem como principal objetivo a produção de gás de síntese através da eletrólise alcalina da água, com recurso à uma solução alcalina de NaOH como eletrólito e, elétrodos de grafite, como fonte de carbono, para uma posterior produção de bicombustíveis sintéticos, a partir do gás de síntese obtido. Deste modo, neste trabalho de investigação estudou-se o comportamento e a otimização de vários parâmetros, a temperatura, a pressão e a intensidade da corrente aplicada ao eletrolisador, tendo por base a monitorização do teor dos gases obtidos (dióxido de carbono, hidrogénio e oxigénio) e, o caudal de gases produzido. Após vários ensaios efetuados, os resultados mais favoráveis foram obtidos utilizando uma concentração de 0,4 M de NaOH, temperatura de 95 ºC, pressão de 4 bar e uma intensidade da corrente de 10 A. Deste modo, obtiveram-se teores de dióxido de carbono, hidrogénio e oxigénio iguais à 28,8 %, 67,3 % e 3,8 %, respetivamente, com um caudal de gás de síntese igual a 72,4 L/h e, com uma potência de 5,1 kW.
Fossil fuels have been, since the industrial revolution, the world's most widely used energy sources. However, with technological development concerns, emerged environmental problems, especially with the greenhouse gases emissions applied in the conventional processes, where fossil fuels are used. In order to overcome this issue, countries are now investing on the use of renewable energy as substitutes for fossil fuels. From the available energy sources, biomass has an enormous potential due to the existent global reserves and it’s a resource that can be converted directly into energy in the form of heat, or electricity, or into biofuels. Synthesis gas (syngas) production requires a versatile support of renewable energy (for example Solar, Wind, Biomass) as this gas can be used for obtaining synthetic biofuels, such as, biomethane (main component biogas, biomethanol, Bio-DME, etc. The main objective of this R&D work is the production of synthesis gas through the alkaline electrolysis of water using an alkaline solution as electrolyte, such as, NaOH, and graphite electrodes, as a carbon source, for posterior production of synthetic biofuels. Thus, in this research work, the behaviour and optimization of several parameters, such as electrolyte concentration, temperature, pressure, and intensity of the current applied to the electrolyser were studied, based on the evaluation and monitorization of outlet gas stream components, like, carbon dioxide, hydrogen and oxygen contents, as well, the gas flow rate produced. After several tests performed, the most favourable results were obtained using a concentration of 0.4 M of NaOH, a temperature of 95 ° C, a pressure of 4 bar and a current intensity of 10 A. With these conditions, it was produced carbon dioxide, hydrogen, and oxygen contents equal to 28.8 %, 67.3 % and 3.8 %, respectively, with the syngas flow rate equal to 72.4 L/h and a power of 5.1 kW.
Fossil fuels have been, since the industrial revolution, the world's most widely used energy sources. However, with technological development concerns, emerged environmental problems, especially with the greenhouse gases emissions applied in the conventional processes, where fossil fuels are used. In order to overcome this issue, countries are now investing on the use of renewable energy as substitutes for fossil fuels. From the available energy sources, biomass has an enormous potential due to the existent global reserves and it’s a resource that can be converted directly into energy in the form of heat, or electricity, or into biofuels. Synthesis gas (syngas) production requires a versatile support of renewable energy (for example Solar, Wind, Biomass) as this gas can be used for obtaining synthetic biofuels, such as, biomethane (main component biogas, biomethanol, Bio-DME, etc. The main objective of this R&D work is the production of synthesis gas through the alkaline electrolysis of water using an alkaline solution as electrolyte, such as, NaOH, and graphite electrodes, as a carbon source, for posterior production of synthetic biofuels. Thus, in this research work, the behaviour and optimization of several parameters, such as electrolyte concentration, temperature, pressure, and intensity of the current applied to the electrolyser were studied, based on the evaluation and monitorization of outlet gas stream components, like, carbon dioxide, hydrogen and oxygen contents, as well, the gas flow rate produced. After several tests performed, the most favourable results were obtained using a concentration of 0.4 M of NaOH, a temperature of 95 ° C, a pressure of 4 bar and a current intensity of 10 A. With these conditions, it was produced carbon dioxide, hydrogen, and oxygen contents equal to 28.8 %, 67.3 % and 3.8 %, respectively, with the syngas flow rate equal to 72.4 L/h and a power of 5.1 kW.
Description
Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica - Ramo Processos Químicos
Keywords
Eletrólise da água Gás de síntese Elétrodos de grafite Energia renovável Catalisadores heterogéneos Electrolysis of water Syngas Graphite electrodes Renewable energy Heterogeneous catalysts
Citation
AUGUSTO, Rosária Reginalde Angelino – Aumento da eficiência da produção eletrolítica de gás de síntese num eletrolisador de 1 kW. Lisboa: Instituto Superior de Engenharia de Lisboa, 2023. Dissertação de Mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa