Estudo termodinâmico e otimização energética das reformas a vapor e autotérmica de etanol
Carregando...
Citações na Scopus
Tipo de produção
Trabalho de Conclusão de Curso
Data
2021-06-17
Autores
Reis, Aline Rocha dos
Santos, Juliana Brunelli Stoco
Pinheiro, Juliana Frias
Dias, Tayrini Fernanda
Santos, Juliana Brunelli Stoco
Pinheiro, Juliana Frias
Dias, Tayrini Fernanda
Orientador
Torres, Ricardo Belchior
Periódico
Título da Revista
ISSN da Revista
Título de Volume
Citação
Texto completo (DOI)
Palavras-chave
etanol,hidrogênio,simulação,otimização,ethanol,hydrogen,simulation,optimization
Resumo
Em 2018, aproximadamente 81% do consumo energético no mundo foi suprido por processos que utilizam combustíveis fósseis (IEA, 2020). Diante da constante preocupação em relação aos impactos ambientais gerados por tais combustíveis, principalmente pelas emissões de gases que causam o efeito estufa, fontes renováveis de energia vêm sendo estudadas e desenvolvidas. Para países com grande produção de álcool etílico, como o Brasil, o maior produtor mundial a partir da cana-de-açúcar, a produção de hidrogênio a partir da reforma de etanol é uma possibilidade técnica e economicamente viável de combustível alternativo, em razão de seu alto poder de combustão e menor impacto ambiental. A proposta deste trabalho foi realizar um estudo termodinâmico e otimização energética das reformas a vapor e autotérmica de etanol, com possibilidade de aplicação em motores de combustão interna (Ciclo Otto). Dessa forma, uma fração do etanol proveniente do tanque de combustível poderia ser direcionada ao reformador para produzir hidrogênio, o qual seria misturado ao etanol, possibilitando um aumento do poder calorífico da mistura combustível e redução na emissão de poluentes. No presente estudo foram simuladas diferentes condições em um reator de Gibbs utilizando o simulador comercial Aspen Plus. Uma estratégia de adição de oxigênio na reação da combustão do etanol foi proposta com o objetivo de diminuir a formação de coque, para evitar contaminação no catalisador. Foi realizada a análise na faixa de temperatura de 400 K a 1200 K, com pressão de 1 a 7 bar, razão de alimentação de vapor de água/etanol (R) entre 0 e 9 e de oxigênio/etanol (Ro) entre 0 e 1,5, em condições ideais. Os resultados mostraram que a produção de hidrogênio na reforma a vapor é favorecida a pressão atmosférica, ao elevar a temperatura e a razão de alimentação de vapor de água/etanol, enquanto a formação de subprodutos é reduzida, exceto o monóxido de carbono. Já na reforma autotérmica, o aumento da razão de alimentação de oxigênio/etanol, desfavorece a formação de hidrogênio em temperaturas acima de 850 K. Entretanto, o coque também tem sua produção reduzida. Com a otimização energética foi possível indicar a região ótima de operação, definida por valores de Ro entre 0 e 0,25 e R a partir de 3 e 2, respectivamente sem formação de coque, utilizando uma temperatura de 900 K no reformador. Foi obtida, na região ótima, uma média de energia específica de mistura combustível etanol-produto de reforma de 30,85 MJ/kg de etanol no sistema, um aumento de 14,68% em relação ao poder calorífico do etanol.
In 2018, approximately 81% of the world's energy consumption was supplied by processes that use fossil fuels (IEA, 2020). In view of the constant concern regarding the environmental impacts generated by such fuels, mainly due to the emission of gases that cause the greenhouse effect, renewable energy sources have been studied and developed. For countries with a large production of ethyl alcohol, such as Brazil, the world's largest producer from sugarcane, the production of hydrogen from ethanol reforming is a technically and economically viable alternative fuel, due to its high combustion power and less environmental impact. The purpose of this work was to perform a thermodynamic study and energy optimization of steam and autothermal reforming of ethanol, with the possibility of application in internal combustion engines (Otto cycle). Thus, a fraction of ethanol from the fuel tank could be directed to the reformer to produce hydrogen, which would be mixed with ethanol, allowing an increase in the calorific power of the fuel mixture and a reduction in the emission of pollutants (GARCIA; LABORDE, 1990). In the present study, different conditions were simulated in a Gibbs reactor using the commercial simulator Aspen Plus. A strategy of adding oxygen in the reaction of combustion of ethanol was proposed with the objective of reducing the formation of coke, to avoid contamination in the catalyst. The analysis was carried out in the temperature range of 400 K to 1200 K, with pressure from 1 to 7 bar, water/ethanol (R) feed ratio between 0 and 9 and oxygen/ethanol (Ro) ratio between 0 and 1.5, under ideal conditions. The results showed that the hydrogen production in the steam reforming is favored at atmospheric pressure, by raising the temperature and the water/ethanol ratio, while the formation of by-products is reduced, except for carbon monoxide. In the autothermal reforming, however, the increase in the oxygen/ethanol feed ratio, favors the formation of hydrogen at temperatures above 850 K. However, coke also has its production reduced. With the energy optimization, it was possible to indicate the optimal operating region, defined by Ro between 0 and 0.25 and R from 3 and 2, respectively, without coke formation, using a temperature of 900 K in the reformer. In the optimal region, an average specific energy of fuel mixture ethanol-reform product of 30.85 MJ/kg of etanol in the system was obtained, an increase of 14.68% in relation to the calorific value of ethanol.
In 2018, approximately 81% of the world's energy consumption was supplied by processes that use fossil fuels (IEA, 2020). In view of the constant concern regarding the environmental impacts generated by such fuels, mainly due to the emission of gases that cause the greenhouse effect, renewable energy sources have been studied and developed. For countries with a large production of ethyl alcohol, such as Brazil, the world's largest producer from sugarcane, the production of hydrogen from ethanol reforming is a technically and economically viable alternative fuel, due to its high combustion power and less environmental impact. The purpose of this work was to perform a thermodynamic study and energy optimization of steam and autothermal reforming of ethanol, with the possibility of application in internal combustion engines (Otto cycle). Thus, a fraction of ethanol from the fuel tank could be directed to the reformer to produce hydrogen, which would be mixed with ethanol, allowing an increase in the calorific power of the fuel mixture and a reduction in the emission of pollutants (GARCIA; LABORDE, 1990). In the present study, different conditions were simulated in a Gibbs reactor using the commercial simulator Aspen Plus. A strategy of adding oxygen in the reaction of combustion of ethanol was proposed with the objective of reducing the formation of coke, to avoid contamination in the catalyst. The analysis was carried out in the temperature range of 400 K to 1200 K, with pressure from 1 to 7 bar, water/ethanol (R) feed ratio between 0 and 9 and oxygen/ethanol (Ro) ratio between 0 and 1.5, under ideal conditions. The results showed that the hydrogen production in the steam reforming is favored at atmospheric pressure, by raising the temperature and the water/ethanol ratio, while the formation of by-products is reduced, except for carbon monoxide. In the autothermal reforming, however, the increase in the oxygen/ethanol feed ratio, favors the formation of hydrogen at temperatures above 850 K. However, coke also has its production reduced. With the energy optimization, it was possible to indicate the optimal operating region, defined by Ro between 0 and 0.25 and R from 3 and 2, respectively, without coke formation, using a temperature of 900 K in the reformer. In the optimal region, an average specific energy of fuel mixture ethanol-reform product of 30.85 MJ/kg of etanol in the system was obtained, an increase of 14.68% in relation to the calorific value of ethanol.