Removal of corrosive contaminants from alkanolamine absorbent process
First Claim
1. In a process for removing CO2 and/or H2S from a gas mixture containing as impurities CO2 and/or H2S and at least one other impurity selected from the group consisting of a cyanide and ammonia, wherein:
- said gas mixture is conveyed to an absorber vessel and contacted with an aqueous absorbent solution containing an acid gas removal solvent to remove CO2 and/or H2S from said gas mixture and form a rich aqueous absorbent solution enriched in CO2 and/or H2S removed from said gas mixture;
said rich aqueous absorbent solution is conveyed from said absorber vessel to a stripping vessel, and thermally stripped of CO2 and/or H2S to form a lean aqueous absorbent solution depleted of CO2 and/or H2S, and an overhead vapor stream rich in CO2 and/or H2S and said at least one other impurity;
said lean aqueous absorbent solution is recycled from said stripping vessel to said absorber vessel to absorb additional amounts of said gas mixture;
said overhead vapor stream is cooled in a heat exchanger to provide a two phase outlet stream and said two phase outlet stream is separated in a separator vessel to provide an acid gas rich stream and an acid gas removal solvent rich aqueous solution; and
recycling said acid gas removal solvent rich aqueous solution for further use in said process, the improvement comprising contacting at least a portion of said acid gas removal solvent rich aqueous solution with an anion exchange resin to remove from said acid gas removal solvent rich aqueous solution at least a part of said at least one other impurity prior to said recycling of said acid gas removal solvent rich aqueous solution for further use in said process.
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Abstract
A process is provided for removing CO2 and/or H2S from a gas mixture containing as impurities CO2 and/or H2S and at least one other impurity selected from the group consisting of a cyanide and ammonia. The process includes contacting at least a portion of the reflux stream from the overhead vapor from a stripping column of an acid gas removal solvent (i.e., alkanolamine) treatment plant with an anion exchange resin to remove corrosive impurities. The ion-exchanged reflux stream is then recycled to the top of the stripping column or into the bulk circulating acid gas removal solvent (i.e., alkanolamine) passing from the bottom of the stripping column.
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Citations
13 Claims
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1. In a process for removing CO2 and/or H2S from a gas mixture containing as impurities CO2 and/or H2S and at least one other impurity selected from the group consisting of a cyanide and ammonia, wherein:
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said gas mixture is conveyed to an absorber vessel and contacted with an aqueous absorbent solution containing an acid gas removal solvent to remove CO2 and/or H2S from said gas mixture and form a rich aqueous absorbent solution enriched in CO2 and/or H2S removed from said gas mixture;
said rich aqueous absorbent solution is conveyed from said absorber vessel to a stripping vessel, and thermally stripped of CO2 and/or H2S to form a lean aqueous absorbent solution depleted of CO2 and/or H2S, and an overhead vapor stream rich in CO2 and/or H2S and said at least one other impurity;
said lean aqueous absorbent solution is recycled from said stripping vessel to said absorber vessel to absorb additional amounts of said gas mixture;
said overhead vapor stream is cooled in a heat exchanger to provide a two phase outlet stream and said two phase outlet stream is separated in a separator vessel to provide an acid gas rich stream and an acid gas removal solvent rich aqueous solution; and
recycling said acid gas removal solvent rich aqueous solution for further use in said process, the improvement comprising contacting at least a portion of said acid gas removal solvent rich aqueous solution with an anion exchange resin to remove from said acid gas removal solvent rich aqueous solution at least a part of said at least one other impurity prior to said recycling of said acid gas removal solvent rich aqueous solution for further use in said process. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
an absorber vessel comprising a sour gas mixture inlet and a rich aqueous absorbent solution outlet below a purified gas outlet and an acid gas removal solvent rich aqueous solution inlet;
a stripping vessel comprising in order from top to bottom, an overhead vapor outlet, a recycled reflux inlet, a rich aqueous absorbent solution inlet and a lean aqueous absorbent solution outlet, wherein said rich aqueous absorbent solution inlet is in fluid communication with said rich aqueous absorbent solution outlet and said lean aqueous absorbent solution outlet is in fluid communication with said acid gas removal solvent rich aqueous solution inlet;
a heat exchanger comprising an overhead vapor stream inlet and a two phase stream outlet on one side and a coolant stream inlet and a coolant stream outlet on the other side wherein said overhead vapor stream inlet is in fluid communication with said overhead vapor stream outlet;
a separator vessel comprising in order from top to bottom, an acid gas rich stream outlet, a two phase stream inlet, and an alkanolamine rich aqueous solution outlet, wherein said two phase stream inlet is in fluid communication with said two phase stream outlet and said alkanolamine rich aqueous solution outlet is in fluid communication with said recycled reflux inlet; and
a resin bed comprising said anion exchange resin, a resin bed inlet, and a resin bed outlet, wherein said resin bed inlet is in fluid communication with said alkanolamine rich aqueous solution outlet, and said resin bed outlet is in fluid communication with said alkanolamine rich aqueous solution inlet.
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13. An alkanolamine processing apparatus adapted to perform the process of claim 1, said apparatus comprising:
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an absorber vessel comprising a sour gas mixture inlet and a rich aqueous absorbent solution outlet below a purified gas outlet and an alkanolamine rich aqueous solution inlet;
a stripping vessel comprising in order from top to bottom, an overhead vapor outlet, a recycled reflux inlet, a rich aqueous absorbent solution inlet and a lean aqueous absorbent solution outlet, wherein said rich aqueous absorbent solution inlet is in fluid communication with said rich aqueous absorbent solution outlet and said lean aqueous absorbent solution outlet is in fluid communication with said alkanolamine rich aqueous solution inlet;
a separator vessel comprising in order from top to bottom, an acid gas rich stream outlet, a rich reflux gas inlet, and an alkanolamine rich aqueous solution outlet, wherein said rich reflux gas inlet is in fluid communication with said rich reflux gas outlet and said alkanolamine rich aqueous solution outlet is in fluid communication with said recycled reflux inlet; and
a resin bed comprising said anion exchange resin, a resin bed inlet, and a resin bed outlet, wherein said resin bed inlet is in fluid communication with said alkanolamine rich aqueous solution outlet, and said resin bed outlet is in fluid communication with said alkanolamine rich aqueous solution inlet. a heat exchanger comprising an overhead vapor stream inlet and a two phase stream outlet on one side and a coolant stream inlet and a coolant stream outlet on the other side wherein said overhead vapor stream inlet is in fluid communication with said overhead vapor stream outlet;
a separator vessel comprising in order from top to bottom, an acid gas rich stream outlet, a two phase stream inlet, and an alkanolamine rich aqueous solution outlet, wherein said two phase stream inlet is in fluid communication with said two phase stream outlet; and
a resin bed comprising said anion exchange resin, a resin bed inlet, and a resin bed outlet, wherein said resin bed inlet is in fluid communication with said alkanolamine rich aqueous solution outlet, and said resin bed outlet is in fluid communication with said recycled reflux inlet.
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Specification