Process for the separation of landfill gas
AssigneeKoch Process Systems, Inc.
InventorsJohn V. O'Brien, Arthur S. Holmes, Richard B. Hopewell
Life of this patent
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Abstract
A recycle process for the separation of landfill gas containing a wide variety of impurities into a carbon dioxide product stream and a fuel-grade-pressurized methane product stream, the process providing for the removal of both the impurities and the carbon dioxide in a cryogenic column as a bottom stream, the separation of the methane from the overhead product stream by a membrane process, and, optionally, the removal of impurities from the carbon dioxide bottom stream in a separate purification column, to recover a high-quality, liquid, carbon dioxide stream.
Claims31
A recycle process for the separation of a landfill feed gas stream, having a high concentration of methane and carbon dioxide and containing undesirable trace gas impurities, into a fuel-or sales-grade gas methane product stream and a liquid carbon dioxide product stream, which process comprises:
- (a) introducing an essentially hydrogen-free, dried, compressed, landfill feed gas stream into a cryogenic distillation column;
- (b) withdrawing a methane-enriched overhead product stream from said distillation column;
- (c) withdrawing an enriched liquid carbon dioxide bottom product stream, containing a major amount of the undesirable impurities, from said distillation column;
- (d) introducing the methane-enriched overhead product stream into a gas-permeation membrane apparatus;
- (e) withdrawing from said membrane apparatus a sales- or fuel-grade gas methane product stream;
- (f) withdrawing from said membrane apparatus a carbon-dioxide-enriched gas permeate stream;
- (g) compressing the carbon-dioxide-enriched gas permeate stream;
- and
- (h) recycling the compressed permeate stream for use in the process.
A recycle process for the apparatus of a landfill feed gas stream, having a high concentration of methane and carbon dioxide and containing undesirable trace gas impurities, into a fuel- or sales-grade gas methane product stream and a liquid carbon dioxide product stream, which process comprises:
- (a) introducing an essentially hydrogen-free, dried, compressed, landfill feed gas stream into a cryogenic distillation column;
- (b) withdrawing a methane-enriched overhead product stream from said distillation column;
- (c) withdrawing an enriched liquid carbon dioxide bottom product stream, containing a major amount of the undesirable impurities, from said distillation column;
- (d) introducing the methane-enriched overhead product stream into a gas-permeation membrane apparatus;
- (e) withdrawing from said membrane apparatus a sales- or fuel-grade gas methane product stream;
- (f) withdrawing from said membrane apparatus a carbon-dioxide-enriched gas permeate stream;
- (g) compressing the carbon-dioxide-enriched gas permeate stream;
- (h) recycling the compressed permeate stream for use in the process;
- (i) introducing the liquid carbon-dioxide-enriched bottom product stream as a feed stream into a low-temperature purification distillation column;
- (j) withdrawing a purified carbon dioxide overhead product stream from said purification column;
- and
- (k) withdrawing a bottom product stream containing essentially all of the undesirable impurities.
A process for the separation of a landfill feed gas stream, having a high concentration of methane and carbon dioxide and containing undesirable trace gas impurities, into an enriched methane product stream and a carbon dioxide product stream, which process comprises:
- (a) introducing a dried, compressed, landfill feed gas stream into a cryogenic distillation column;
- (b) withdrawing a methane-enriched overhead product stream, essentially free of impurities, from said distillation column;
- (c) withdrawing an enriched liquid carbon dioxide bottom product stream, containing essentially all of the undesirable impurities, from said distillation column;
- (d) introducing the carbon dioxide bottom product stream as a feed stream into a low-temperature purification distillation column;
- (e) withdrawing a purified carbon dioxide overhead product stream from said purification distillation column;
- and
- (f) withdrawing a bottom product stream containing essentially all of the undesirable impurities from said purification distillation column.
A process for the separation of a landfill feed gas stream having a high concentration of both methane and carbonn dioxide and containing undesirable trace gas impurities comprising sulfur compounds, halogenated hydrocarbon compounds, ketones and hydrocarbons, which process comprises:
- (a) introducing a dried, compressed, landfill feed gas stream into a cryogenic distillation column;
- (b) withdrawing from said distillation column a methane-enriched overhead product stream essentially free of the trace gas impurities;
- and
- (c) withdrawing from said distillation column a liquid carbon-dioxide-enriched bottom product stream containing essentially all of the undesirable trace gas impurities.
Dependencies are inferred from the claim text.