Publicação
Modeling and simulation of a biomass pyrolysis and gasification process
| Resumo: | Global energy demand has increased exponentially, and the trend is to continue to increase. The form of conventional energy production, primarily from fossil and non-renewable energies, is very harmful to the planet. Biomass is a good alternative to fossil energies due to being renewable and possessing virtually no production of carbon dioxide, one of the main gases that cause the greenhouse effect. There are several ways to use biomass, it should be mentioned: pyrolysis, gasification for fuel production, direct burning, bio digestion and others. The objective is to review the generation of waste in Portugal, present the classic models of pyrolysis and biomass gasification as well as their stages, and later develop a specific model for the simulation of a downdraft due to the high temperature selected gasifier process using Python and the UniSim Design chemical processes simulator software. The study was made using two different sources of biomass, olive pit and wood residue. A kinetic and thermodynamic model was developed to first evaluate the pyrolysis process, and using the software Unisim Design a gasification process was developed. The main results obtained allow the conclusion that the biomass with higher moisture content (wood residue) was more susceptible to temperature influence in the process than the biomass with lower moisture content (olive pit), leading to the formation of compositions for H2 of approximately 0.246 (mass fraction) between 100 and 400 °C for olive pit and 0.106 and 0.0105 (mass fraction) for wood residue between 100 and 400 °C, in stoichiometric equivalence between biomass, steam and water. Olive pit generated higher hydrogen and methane formation. Increasing the temperature and steam inlet favors the formation of H2, CO and CO2 while decreasing CH4 formation, H2 obtained a variation of 0.250 to 0.234 (mass fraction) for olive pit and 0.106 and 0.103 (mass fraction) for wood residing in a biomass/steam molar equivalence between 0.5 and 4. Increasing the steam flow results in increased formation of CO2 and H2, and increased airflow decreases the formation of these products. The increase in steam flow decreases the formation of CH4 and CO. Steam temperature of 250°C is the one with the highest hydrogen yield, and lower methane formation. |
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| Autores principais: | Bonifácio, Matheus |
| Assunto: | Biomass Gasification Pyrolysis Unisim design software Simulation |
| Ano: | 2023 |
| 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: | Global energy demand has increased exponentially, and the trend is to continue to increase. The form of conventional energy production, primarily from fossil and non-renewable energies, is very harmful to the planet. Biomass is a good alternative to fossil energies due to being renewable and possessing virtually no production of carbon dioxide, one of the main gases that cause the greenhouse effect. There are several ways to use biomass, it should be mentioned: pyrolysis, gasification for fuel production, direct burning, bio digestion and others. The objective is to review the generation of waste in Portugal, present the classic models of pyrolysis and biomass gasification as well as their stages, and later develop a specific model for the simulation of a downdraft due to the high temperature selected gasifier process using Python and the UniSim Design chemical processes simulator software. The study was made using two different sources of biomass, olive pit and wood residue. A kinetic and thermodynamic model was developed to first evaluate the pyrolysis process, and using the software Unisim Design a gasification process was developed. The main results obtained allow the conclusion that the biomass with higher moisture content (wood residue) was more susceptible to temperature influence in the process than the biomass with lower moisture content (olive pit), leading to the formation of compositions for H2 of approximately 0.246 (mass fraction) between 100 and 400 °C for olive pit and 0.106 and 0.0105 (mass fraction) for wood residue between 100 and 400 °C, in stoichiometric equivalence between biomass, steam and water. Olive pit generated higher hydrogen and methane formation. Increasing the temperature and steam inlet favors the formation of H2, CO and CO2 while decreasing CH4 formation, H2 obtained a variation of 0.250 to 0.234 (mass fraction) for olive pit and 0.106 and 0.103 (mass fraction) for wood residing in a biomass/steam molar equivalence between 0.5 and 4. Increasing the steam flow results in increased formation of CO2 and H2, and increased airflow decreases the formation of these products. The increase in steam flow decreases the formation of CH4 and CO. Steam temperature of 250°C is the one with the highest hydrogen yield, and lower methane formation. |
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