Ciclos combinados e de cogeração: aplicações para o Brasil a partir do gás natural e biogás
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Tipo
TCC
Data de publicação
2021-06-15
Periódico
Citações (Scopus)
Autores
Rodrigues, Gabriel Ishii
Orientador
Caly, José Pucci
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Resumo
Os ciclos combinados são caracterizados pela recuperação do calor rejeitado por duas ou mais máquinas térmicas, para a geração de energia elétrica e/ou térmica, tal configuração apresenta-se como uma solução para aumentar a eficiência da geração de eletricidade, para cerca de 50%, o que traria uma considerável redução do consumo de combustíveis para uma mesma potência gerada. Com a possibilidade ainda de utilizar fontes de combustíveis renováveis, tal como o biogás, em substituição ao gás natural, este que corresponde a cerca 30% da matriz elétrica global. Novas tecnologias apresentam aplicações modernas também para o Ciclo de Rankine, tal como as células de combustível, na qual o rejeito térmico gerado na combustão do hidrogênio pode ser reaproveitado na geração de energia. Estas tecnologias podem diversificar a matriz elétrica brasileira, ao mesmo tempo que reduzem os impactos ambientais. Foi realizada uma pesquisa bibliográfica para a formulação dos cenários matemáticos propostos, abordando tópicos de mecânica dos fluidos, termodinâmica, e sistemas térmicos. Foram elaborados cenários de operação a partir de características técnicas de equipamentos reais para a determinação de parâmetros médios de operação para sistemas a vapor. Nos resultados simulados, obteve-se um ganho de eficiência médio teórico de 7% para a microturbina a vapor; e uma pequena queda se comparada com o ciclo Brayton, que apresentou 33% de eficiência térmica. O ganho de eficiência no ciclo de Rankine proporcionou uma redução aproximada de 5,7% de consumo de combustível, a partir da energia não utilizada no sistema de potência a gás.
Combined cycles are characterized by the retrieval of the waste heat rejected by two or more thermal machines, for generation of electric energy; such configuration is presented as a solution to increase in 50% the efficiency of electricity’s production, which would reduce the use of fuels for the same power generated. With the potential, in addition to using renewable sources, such as biogas, replacing the natural gas, which is responsible for nearly 30% of the global power grid. New technologies present modern applications as well for the Rankine Cycle, such as fuel cells, in which the waste heat generated in the combustion of the hydrogen can be recycled in energy production. These technologies can diversify the Brazilian power grid, while simultaneously, and reduce the environmental impacts. Research was made to formulate the mathematical sceneries proposed, addressing topics as fluid mechanics, thermodynamic and thermal systems. Scenarios of operation were designed from technical characteristics of real equipment to determinate the standard intermediate parameters of operation of steam systems. In addition, a study was made to add a regenerator that uses flue gas of a gas microturbine, in a steamed power cycle. In the earnings, it achieved a gain of 7% average theoretical efficiency for a steam microturbine; and a small decrease if compared to the Brayton cycle, which performed 33% of its thermal efficiency. The gain of efficiency in the Rankine cycle provided an approximated 5.7% saving in fuel consumption, operating from the non-utilized in a gas power system.
Combined cycles are characterized by the retrieval of the waste heat rejected by two or more thermal machines, for generation of electric energy; such configuration is presented as a solution to increase in 50% the efficiency of electricity’s production, which would reduce the use of fuels for the same power generated. With the potential, in addition to using renewable sources, such as biogas, replacing the natural gas, which is responsible for nearly 30% of the global power grid. New technologies present modern applications as well for the Rankine Cycle, such as fuel cells, in which the waste heat generated in the combustion of the hydrogen can be recycled in energy production. These technologies can diversify the Brazilian power grid, while simultaneously, and reduce the environmental impacts. Research was made to formulate the mathematical sceneries proposed, addressing topics as fluid mechanics, thermodynamic and thermal systems. Scenarios of operation were designed from technical characteristics of real equipment to determinate the standard intermediate parameters of operation of steam systems. In addition, a study was made to add a regenerator that uses flue gas of a gas microturbine, in a steamed power cycle. In the earnings, it achieved a gain of 7% average theoretical efficiency for a steam microturbine; and a small decrease if compared to the Brayton cycle, which performed 33% of its thermal efficiency. The gain of efficiency in the Rankine cycle provided an approximated 5.7% saving in fuel consumption, operating from the non-utilized in a gas power system.
Descrição
Palavras-chave
recuperação de energia , ciclo de rankine , energias alternativas , energy recovery , rankine cycle , alternative energies