Mercury removal from gaseous process streams
First Claim
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1. A process for removing mercury from a gaseous process stream, said process comprising:
- contacting a first mercury-containing gaseous process stream with a regenerable mercury scavenger solution to form a treated stream having a reduced mercury content and a used scavenger solution having an increased mercury content, the regenerable mercury scavenger solution comprising;
a) nitric acid effective to oxidize mercury contained within the first mercury-containing gaseous process stream to form mercury cations, b) a complexing agent suitable for forming a soluble mercury compound when contacting the mercury cations, and c) a solvent effective to dissolve the soluble mercury compound.
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Abstract
A process for removing mercury from a gaseous process stream. The process involves contacting a mercury-containing gaseous process stream with a regenerable mercury scavenger solution to form a treated stream having a reduced mercury content as compared to the mercury-containing gaseous process stream and a used scavenger solution having an increased mercury content. The regenerable mercury scavenger solution contains an oxidizing agent such as nitric acid, a complexing agent such as oxygen-containing agents and/or thiol and a solvent, for example, a mixture of methanol and water.
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Citations
27 Claims
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1. A process for removing mercury from a gaseous process stream, said process comprising:
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contacting a first mercury-containing gaseous process stream with a regenerable mercury scavenger solution to form a treated stream having a reduced mercury content and a used scavenger solution having an increased mercury content, the regenerable mercury scavenger solution comprising;
a) nitric acid effective to oxidize mercury contained within the first mercury-containing gaseous process stream to form mercury cations, b) a complexing agent suitable for forming a soluble mercury compound when contacting the mercury cations, and c) a solvent effective to dissolve the soluble mercury compound. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
regenerating the used scavenger solution.
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3. The process of claim 2 wherein the used scavenger solution is regenerated continuously.
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4. The process of claim 2 wherein the used scavenger solution is regenerated in a batch fashion.
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5. The process of claim 1 wherein the solvent is stable at temperatures up to about 300°
- F.
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6. The process of claim 5 wherein the solvent has a vapor pressure of less than about 0.01 mm Hg at 20°
- C.
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7. The process of claim 6 wherein the solvent comprises an aqueous solution of potassium carbonate.
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8. The process of claim 6 wherein the solvent comprises at least one member selected from the group consisting of 1,2,3,4 tetrahydronaphthalene, N,N dimethylaniline, diphenyl ether, dibenzyl ether, terphenyls, diphenylethanes, alkylated polycyclic aromatics and mixtures thereof.
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9. The process of claim 1 wherein the first mercury-containing gaseous process stream is a flue gas resulting from coal combustion.
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10. The process of claim 1 wherein the nitric acid is approximately 0.1 N.
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11. The process of claim 1 wherein the complexing agent is selected from the group consisting of oxygen-containing compounds, sulfur-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds and mixtures thereof.
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12. The process of claim 1 wherein the complexing agent is selected from the group consisting of a thiol, a dithiocarbamic acid, a thiocarbamic acid, a thiocarbazone, a cryptate and mixtures thereof.
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13. The process of claim 1 wherein the solvent comprises a mixture of methanol and water.
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14. The process of claim 1 wherein the solvent has a freezing point below −
- 40°
F.
- 40°
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15. A process for removing mercury from a flue gas process stream, said process comprising:
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contacting a mercury-containing flue gas process stream with a regenerable mercury scavenger solution to form a treated stream having a reduced mercury content and a used scavenger solution having an increased mercury content, the regenerable mercury scavenger solution comprising;
a) nitric acid effective to oxidize mercury contained within the mercury-containing flue gas process stream to form mercury cations, b) a complexing agent suitable for forming a soluble mercury compound when contacting the mercury cations, and c) a solvent effective to dissolve the soluble mercury compound and regenerating the used scavenger solution. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A process for removing mercury from a natural gas stream, said process comprising:
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contacting a mercury-containing natural gas feed stream with a regenerable mercury scavenger solution to form a treated stream having a reduced mercury content and a used scavenger solution having an increased mercury content, the regenerable mercury scavenger solution comprising;
a) nitric acid effective to oxidize mercury contained within the natural gas feed stream to form mercury cations, b) a complexing agent suitable for forming a soluble mercury compound when contacting the mercury cations, and c) a solvent effective to dissolve the soluble mercury compound and regenerating the used scavenger solution. - View Dependent Claims (24, 25, 26, 27)
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Specification