Method for distilling a gas stream containing oxygen
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsPaul Terrien, Nicolas Chantant
Life of this patent
Estimating the term…
Abstract
A process for producing biomethane by scrubbing a biogas feed stream includes introducing the feed gas stream into a pretreatment unit wherein a CO2-depleted gas stream is partially separated from a CO2 stream and an oxygen stream and is compressed to a pressure P1 above 25 bar abs. Subjecting the CO2-depleted gas stream to cryogenic separation in a distillation column to separate a nitrogen stream and produce a CH4-enriched stream, the distillation column comprising n plates, n being an integer between 8 and 100. Recovering a pressurized CH4-enriched stream by pumping the CO2-depleted gas stream to a pressure P2 above 25 bar absolute.
Claims6
A process for producing biomethane by scrubbing a biogas feed stream, the process comprising:
- introducing the feed gas stream into a pretreatment unit wherein a CO2-depleted gas stream is partially separated from a CO2 stream and an oxygen stream and is compressed to a pressure P1 above 25 bar absolute;
- subjecting the CO2-depleted gas stream to cryogenic separation in a distillation column to separate a nitrogen stream and produce a CH4-enriched stream, the distillation column comprising n plates, n being an integer between 8 and 100;
- recovering a pressurized CH4-enriched stream by pumping the CH4-enriched stream to a pressure P2 above 25 bar absolute,
- wherein the CO2-depleted gas stream has an oxygen concentration equal to C1 and wherein:
- when C1 is strictly greater than 1 mol %, the process is stopped;
- and
- when C1 is strictly greater than 0.1 mol % and less than 1 mol %, the CO2-depleted gas stream is introduced into the distillation column at a level between plate n-4 and plate n, plate n being the plate that is positioned the highest in said column.
Dependencies are inferred from the claim text.