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Controlled Solid-Vapour CO2 phase transitions in methane rich streams applied to biogas upgrading

Abstract : Cryogenic systems are one of the most promising and still rising technologies for upgrading biogas as it is solvent free and can operate at atmospheric pressure. In this work a new concept for cold recovery by controlled sublimation is presented. A cold gas flow is used as a defrosting gas that will sublimate the frost using the partial pressure gradient between the frost and the gas flow instead of wasting the cold by convective heat transfer. Prior to this step, CO2 deposition should be studied. CO2 frost formation and growth is thoroughly detailed and a model is presented to better explain how CO2 is separated from biogas and deposits on a cold surface. A comparison between the flat plate and the tube configurations showed that the latter was better for CO2 capture in a cryogenic system in terms of heat and mass transfer but it presents a problem of clogging as frost increases inside the tube. The study of frost formation along the tube showed a delay in the starting time of deposition at position further from the biogas inlet. A process for biogas cryogenic upgrading and biomethane liquefaction was presented with calculations for all the components included in the system. Simulation results show that cold recovery is possible by controlled sublimation and the tube temperature reached values lower to the gas flow temperature which is not possible by single convective heat transfer. The concept works best for lower CO2 concentrations in the inlet biogas if the frosting and defrosting phases are to be completed at the same time. Finally, an experiment was conducted to validate the concept of cold recovery by controlled sublimation, for which results have shown the potential to totally avoid cold utilities use in the cryogenic capture of CO2.
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https://pastel.archives-ouvertes.fr/tel-03118446
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Submitted on : Friday, January 22, 2021 - 11:28:09 AM
Last modification on : Sunday, January 24, 2021 - 3:04:22 AM

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2019PSLEM069_archivage.pdf
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  • HAL Id : tel-03118446, version 1

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Sylvain Haddad. Controlled Solid-Vapour CO2 phase transitions in methane rich streams applied to biogas upgrading. Chemical and Process Engineering. Université Paris sciences et lettres, 2019. English. ⟨NNT : 2019PSLEM069⟩. ⟨tel-03118446⟩

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