Avaliação dos parâmetros do adoçamento do gás natural
Data
2022-02-03
Autores
Costa, Liliane Martins 
Orientadores
Komesu, Andrea
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O gás natural tem o metano (CH4) como principal componente, porém apresenta contaminantes como gás sulfídrico (H2S) e dióxido de carbono (CO2). Para fins comerciais, o gás natural deve estar isento desses contaminantes. No seu condicionamento, o gás natural é submetido a etapa de adoçamento, que consiste na remoção dos gases ácidos H2S e CO2, através de soluções de aminas, tais como a monoetanolamina (MEA), metildietanolamina (MDEA) e a dietanolamina (DEA). Esses contaminantes podem provocar a formação de hidratos, obstruindo o transporte do gás e acelerando o processo de corrosão nas tubulações de um gasoduto. Assim, este trabalho teve como objetivo avaliar o processo de adoçamento utilizando uma coluna de absorção com o auxílio do software ASPEN PLUS®. Inicialmente, foi realizada uma simulação baseada nas condições normais de operação de uma unidade de tratamento de gás natural. A partir dessa simulação inicial, foram realizadas novas simulações alterando os parâmetros que mais impactam na etapa de adoçamento. Foram avaliados os seguintes parâmetros para a coluna de absorção: temperatura da amina na alimentação da coluna; número de pratos; porcentagem em massa de entrada da amina (concentração); pressão do absorvedor e a razão L/G (vazão mássica de amina com água pela vazão mássica de gás natural). Os parâmetros avaliados para a coluna de regeneração foram: número de pratos e o prato de alimentação. Foram utilizados dois modelos termodinâmicos, o NRTL e o Wilson, e duas aminas, a DEA e a MDEA. Os resultados mostraram que o modelo NRTL ajustou-se melhor a simulação nas seguintes condições de processo: número de pratos igual a 10; pressão no absorvedor de 68 atm.; temperatura da corrente de entrada da amina de 34 °C; quantidade de amina de 25% e razão L/G de 1,8. O processo utilizando o modelo NRTL apresentou uma extração de 26% a mais de CO2 do gás natural, para ambas as aminas, quando comparado ao modelo Wilson, e para o H2S esse percentual foi de 28%. E entre as aminas avaliadas, a amina DEA obteve um melhor desempenho, para a extração dos gases ácidos, com um percentual de 4% a mais de extração para ambos os modelos termodinâmicos. Além disso, com o aumento de temperatura de entrada da amina, obteve-se uma piora no desempenho de extração dos gases ácidos da coluna. Nas condições de maior
razão de refluxo (2,5), pressão (68 atm) e maior concentração de amina, elevou-se a quantidade de gases ácidos na corrente de gás doce. Uma quantidade maior de número de pratos melhorou a eficiência para o absorvedor, tendo-se uma maior extração dos gases ácidos. A alimentação realizada mais próxima do fundo da coluna regeneradora (8° prato) foi mais eficiente na recuperação das aminas. Por fim, os resultados das simulações foram comparados aos valores permitidos pela norma ANP 16/2008 para verificar quais simulações obtiveram resultados dentro dos valores permitidos pela norma para comercialização do gás natural no Brasil.
Natural gas has methane (CH4) as its main component, however has contaminants such as hydrogen sulphide (H2S) and carbon dioxide (CO2). For commercial purposes, natural gas has must be free from these contaminants. In its conditioning, natural gas undergoes a sweetening process, which consists of the removal of H2S and CO2 acid gases, through amine solutions, such as monoethanolamine (MEA), methyldiethanolamine (MDEA) and diethanolamine (DEA). These contaminants can cause the formation of hydrates, obstructing the gas transport and accelerating the corrosion process in the pipes. Therefore, this work aims to evaluate the sweetening process using an absorption column. The process parameters with the greatest impact on the sweetening proccess stage will be evaluated using pure amines and at different concentrations, as well with regeneration. Initially, a simulation was performed based on the normal operating conditions of a natural gas treatment unit. From this initial simulation, new simulations were performed changing the parameters that most impact the sweetening stage. The following parameters were evaluated for the absorption column: Amine temperature in column feed; number of plates; percentage of amine input mass (concentration); absorber pressure and L/G ratio (mass flow of amine with water, by the mass flow of natural gas). The parameters evaluated for the regeneration column were: number of plates in the column and the feeding plate. Two thermodynamic models were used, NRTL and Wilson and two amines, DEA and MDEA. The results showed that the NRTL model better adjusted the simulation under the following process conditions: Number of dishes equal to 10; pressure in the absorber of 68 atm.; amine input current temperature of 34 °C; amount of amine of 25% and L/G ratio of 1,8. The process using the NRTL model presented an extraction of 26% more CO2 from natural gas, for both amines, when compared to the Wilson model, and for H2S this percentage was 28%. And among the amines evaluated, the dea amine obtained a better performance, for the extraction of acid gases, with an increase of 4% more extraction for both thermodynamic models. In addition, with the increase in the input temperature of the amine, there was a worsening in the extraction performance of the acid gases of the column. Under the conditions of higher reflux ratio (2.5), pressure (68 atm) and higher concentration of amine, the amount of acid gases in the sweet gas stream was increased. A larger number of dishes improved the efficiency for the absorber, with a greater extraction of acid gases. The feeding performed closer to the bottom of the regenerating column (8° plate) was more efficient in the recovery of amines. Finally, the results of the simulations were compared to the values allowed by ANP 16/2008 to verify which simulations obtained results within the values allowed by the norm, for the commercialization of natural gas in Brazil
Natural gas has methane (CH4) as its main component, however has contaminants such as hydrogen sulphide (H2S) and carbon dioxide (CO2). For commercial purposes, natural gas has must be free from these contaminants. In its conditioning, natural gas undergoes a sweetening process, which consists of the removal of H2S and CO2 acid gases, through amine solutions, such as monoethanolamine (MEA), methyldiethanolamine (MDEA) and diethanolamine (DEA). These contaminants can cause the formation of hydrates, obstructing the gas transport and accelerating the corrosion process in the pipes. Therefore, this work aims to evaluate the sweetening process using an absorption column. The process parameters with the greatest impact on the sweetening proccess stage will be evaluated using pure amines and at different concentrations, as well with regeneration. Initially, a simulation was performed based on the normal operating conditions of a natural gas treatment unit. From this initial simulation, new simulations were performed changing the parameters that most impact the sweetening stage. The following parameters were evaluated for the absorption column: Amine temperature in column feed; number of plates; percentage of amine input mass (concentration); absorber pressure and L/G ratio (mass flow of amine with water, by the mass flow of natural gas). The parameters evaluated for the regeneration column were: number of plates in the column and the feeding plate. Two thermodynamic models were used, NRTL and Wilson and two amines, DEA and MDEA. The results showed that the NRTL model better adjusted the simulation under the following process conditions: Number of dishes equal to 10; pressure in the absorber of 68 atm.; amine input current temperature of 34 °C; amount of amine of 25% and L/G ratio of 1,8. The process using the NRTL model presented an extraction of 26% more CO2 from natural gas, for both amines, when compared to the Wilson model, and for H2S this percentage was 28%. And among the amines evaluated, the dea amine obtained a better performance, for the extraction of acid gases, with an increase of 4% more extraction for both thermodynamic models. In addition, with the increase in the input temperature of the amine, there was a worsening in the extraction performance of the acid gases of the column. Under the conditions of higher reflux ratio (2.5), pressure (68 atm) and higher concentration of amine, the amount of acid gases in the sweet gas stream was increased. A larger number of dishes improved the efficiency for the absorber, with a greater extraction of acid gases. The feeding performed closer to the bottom of the regenerating column (8° plate) was more efficient in the recovery of amines. Finally, the results of the simulations were compared to the values allowed by ANP 16/2008 to verify which simulations obtained results within the values allowed by the norm, for the commercialization of natural gas in Brazil
Descrição
Citação
Costa,Liliane. Avaliação dos parâmetros do adoçamento do gás natural. UNIFESP,2022
COSTA, Liliane Martins. Avaliação dos parâmetros do adoçamento do gás natural. 2022. 68 f. Trabalho de conclusão de curso (Graduação em Engenharia de Petróleo) - Instituto do Mar, Universidade Federal de São Paulo, Santos, 2022.
COSTA, Liliane Martins. Avaliação dos parâmetros do adoçamento do gás natural. 2022. 68 f. Trabalho de conclusão de curso (Graduação em Engenharia de Petróleo) - Instituto do Mar, Universidade Federal de São Paulo, Santos, 2022.