Landfill gas recovery
First Claim
1. A process for separating carbon dioxide from a landfill gas feed stream containing carbon dioxide, methane and trace contaminants of relatively higher boiling gases, comprising the stepscompressing the landfill gas feed stream and removing water therefrom to produce a dehydrated gas stream containing said methane, carbon dioxide and trace contaminants,introducing said dehydrated gas stream into an absorption column means for absorbing said contaminants with a carbon dioxide absorbent primarily comprising said carbon dioxide present in said landfill gas stream,withdrawing from said absorption column means, at a first location, a spent absorbent stream containing no more than about 35% of the carbon dioxide contained in the landfill gas feed stream and substantially all of said gas contaminants, withdrawing from said absorption column at a second location above said first location, a carbon dioxide product stream substantially free of contaminants containing a substantial portion of the carbon dioxide originally present in said landfill gas feed stream, andalso withdrawing from said absorption column means a methane product stream substantially free of said contaminants and containing most of the methane originally contained in said landfill gas feed stream.
4 Assignments
0 Petitions
Accused Products
Abstract
A process for concentrating and recovering methane and carbon dioxide from landfill gas includes absorption of commonly occurring pollutants using a reduced amount of carbon dioxide absorbent which itself may be an in situ derived and recoverable constituent. Separated methane may be concentrated into a high heating value fuel, and a highly pure food-grade carbon dioxide product may also be recovered. Process streams may be used to provide fuel for compression and refrigeration and/or to regenerate carbon dioxide absorbent.
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Citations
33 Claims
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1. A process for separating carbon dioxide from a landfill gas feed stream containing carbon dioxide, methane and trace contaminants of relatively higher boiling gases, comprising the steps
compressing the landfill gas feed stream and removing water therefrom to produce a dehydrated gas stream containing said methane, carbon dioxide and trace contaminants, introducing said dehydrated gas stream into an absorption column means for absorbing said contaminants with a carbon dioxide absorbent primarily comprising said carbon dioxide present in said landfill gas stream, withdrawing from said absorption column means, at a first location, a spent absorbent stream containing no more than about 35% of the carbon dioxide contained in the landfill gas feed stream and substantially all of said gas contaminants, withdrawing from said absorption column at a second location above said first location, a carbon dioxide product stream substantially free of contaminants containing a substantial portion of the carbon dioxide originally present in said landfill gas feed stream, and also withdrawing from said absorption column means a methane product stream substantially free of said contaminants and containing most of the methane originally contained in said landfill gas feed stream.
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18. A process for separating carbon dioxide from a landfill gas feed stream containing carbon dioxide, methane and trace contaminants of relatively higher boiling gases comprising the steps of:
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compressing the landfill gas feed stream and removing water therefrom to produce a dehydrated gas stream containing said methane, carbon dioxide and trace contaminants, introducing said dehydrated gas stream into an absorption column for absorbing said contaminants with a carbon dioxide absorbent comprising a portion of said carbon dioxide present in said landfill gas stream, and withdrawing from said absorption column, at a first location, a spent absorbent stream comprising no more than about about 35% of the carbon dioxide contained in the landfill gas feed stream and substantially all of said gas contaminants, withdrawing from said absorption column, at a second location above said first location, a side product stream containing a substantial portion of the carbon dioxide originally contained in said landfill gas feed stream, and withdrawing from said absorption column a methane product stream containing most of the methane originally contained in the landfill gas feed stream. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A process for separating carbon dioxide from a landfill gas feed stream containing carbon dioxide, methane and trace contaminants of relatively higher boiling gases comprising the steps of:
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compressing the landfill gas feed stream and removing water therefrom to produce a dehydrated gas stream containing said methane, carbon dioxide and trace contaminants, introducing said dehydrated gas stream into a first absorption column for absorbing said contaminants with a carbon dioxide absorbent comprising a portion of said carbon dioxide present in said landfill gas feed stream, withdrawing from said first absorption column absorber, at a first location, a spent absorbent stream comprising no more than about about 35% of the carbon dioxide contained in the landfill gas feed stream and substantially all of said gas contaminants, and a combined overhead product stream enriched in methane and containing carbon dioxide to be recovered, introducing said combined overhead product stream from said first absorption column, as a feed, into a second absorption column to separate carbon dioxide from methane using a carbon dioxide absorbent to form a bottom product containing methane and a substantial portion of the carbon dioxide originally present in the landfill gas feed stream and a methane product stream substantially free of said contaminants and containing most of the methane originally present in the landfill gas stream. - View Dependent Claims (28, 29, 30, 31, 32)
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Specification