Publicação
Biomass gasification processes - modeling and simulation
| Resumo: | Thermochemical processes prove to be a sustainable way of using residual biomass, replacing non-renewable sources such as coal and petroleum derivatives, and serving as a means for the creation of Synthesis Gas, or Syngas, mostly consisting of hydrogen gas and carbon monoxide, which is the basis for the chemical industry and power generation. The modeling and simulation of this process is feasible, as it portrays real gasifiers, such as Downdraft type gasifiers, in order to test variables and verify the system's behaviors when changing them. However, there is still some difficulty in modeling Pyrolysis, due to the complexity of this process, as well as predicting the tar generated during the process. Thus, the present study aims to model and simulate using the UniSim Design software, the gasification of three biomass residues from Portuguese agriculture: grape marc, olive trees, and corn straw residues, in an attempt to predict Syngas production under different process conditions and validate the method proposed comparing with data from the literature. Pyrolysis modeling was performed using a second-order model based on the process temperature, providing the yields of gases: CO2, CO, H2, and CH4, residual coal, and tar, which is composed of benzene, toluene, and naphthalene. Regarding the results obtained, both Pyrolysis and the general model, even at different conditions of mass flow of air and steam inlet, were compatible with results obtained in the literature, quantitatively and qualitatively. The rise in equivalence ratio (ER) from 0.23 to 0.54 caused an increase in the process temperature, as well as in the molar fraction of H2 and CO while reducing the other components, thus consuming the tar, for the biomasses in the ER range 0.36-0.37. The increase in the steam-to-biomass ratio (S/B) from 0 to 0.95 had a positive effect on the H2 and CO2 components, while it decreased the others, having no effect on the tar fraction. For both analyses, corn straw residue was converted into the richest gas in hydrogen, with the peak of the fraction of the component in Syngas, free of water and nitrogen, being 0.48 and 0.52, for ER and S/B ratio, respectively. |
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| Autores principais: | Maldonado, Pedro |
| Assunto: | Biomass gasification Pyrolysis process Downdraft gasifier Syngas Simulation UniSim design |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Thermochemical processes prove to be a sustainable way of using residual biomass, replacing non-renewable sources such as coal and petroleum derivatives, and serving as a means for the creation of Synthesis Gas, or Syngas, mostly consisting of hydrogen gas and carbon monoxide, which is the basis for the chemical industry and power generation. The modeling and simulation of this process is feasible, as it portrays real gasifiers, such as Downdraft type gasifiers, in order to test variables and verify the system's behaviors when changing them. However, there is still some difficulty in modeling Pyrolysis, due to the complexity of this process, as well as predicting the tar generated during the process. Thus, the present study aims to model and simulate using the UniSim Design software, the gasification of three biomass residues from Portuguese agriculture: grape marc, olive trees, and corn straw residues, in an attempt to predict Syngas production under different process conditions and validate the method proposed comparing with data from the literature. Pyrolysis modeling was performed using a second-order model based on the process temperature, providing the yields of gases: CO2, CO, H2, and CH4, residual coal, and tar, which is composed of benzene, toluene, and naphthalene. Regarding the results obtained, both Pyrolysis and the general model, even at different conditions of mass flow of air and steam inlet, were compatible with results obtained in the literature, quantitatively and qualitatively. The rise in equivalence ratio (ER) from 0.23 to 0.54 caused an increase in the process temperature, as well as in the molar fraction of H2 and CO while reducing the other components, thus consuming the tar, for the biomasses in the ER range 0.36-0.37. The increase in the steam-to-biomass ratio (S/B) from 0 to 0.95 had a positive effect on the H2 and CO2 components, while it decreased the others, having no effect on the tar fraction. For both analyses, corn straw residue was converted into the richest gas in hydrogen, with the peak of the fraction of the component in Syngas, free of water and nitrogen, being 0.48 and 0.52, for ER and S/B ratio, respectively. |
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