Mercury removal with amine sorbents
View Patent ↗Methods and apparatus relate to treatment of fluids to remove mercury contaminants in the fluid. Contact of the fluid with an amine that has absorbed a sulfur compound causes the mercury contaminants to be absorbed by the amine. Phase separation then removes from the fluid the amine loaded with the mercury contaminants such that a treated product remains.
1. A method comprising:
preparing a mixture by introducing a mercury-containing hydrocarbon liquid into contact with an aqueous liquid containing an amine that has absorbed sulfur, wherein the aqueous liquid thereby absorbs mercury;
in a mercury removal unit, separating the mixture into a hydrocarbon phase and an aqueous phase;
extracting the hydrocarbon phase separated from the aqueous phase to provide a treated hydrocarbon liquid;
bypassing the mercury removal unit with a portion of the aqueous liquid containing the amine that has absorbed sulfur and directing the portion into a regeneration unit;
in the regeneration unit, desorbing sulfur and mercury from the aqueous liquid containing the amine; and
recycling the aqueous liquid containing the amine by directing it from the regeneration unit to a gas stripper unit.
2. The method according to claim 1 , further comprising stripping a sour gas with the amine, wherein hydrogen sulfide transfers from the sour gas to the amine to provide treated gas and the aqueous liquid.
3. The method according to claim 1 , wherein the amine is diethanol amine.
4. The method according to claim 1 , wherein the amine is diethanol amine, which has absorbed hydrogen sulfide.
5. The method according to claim 1 , wherein the aqueous liquid contains at least 250 parts per million by weight of the sulfur.
6. The method according to claim 1 , wherein the mercury-containing hydrocarbon liquid and the aqueous liquid are contacted while at a temperature of at least 40° C.
7. The method according to claim 1 , wherein the mercury-containing hydrocarbon liquid and the aqueous liquid are contacted while at a temperature of at least 40° C. and the aqueous liquid contains at least 250 parts per million by weight of the sulfur.
8. The method according to claim 1 , wherein the treated hydrocarbon liquid contains less than 70% of the mercury contained in an equal volume of the mercury-containing hydrocarbon liquid.
9. The method according to claim 1 , wherein the amine has absorbed the sulfur in a compound having a formula R 1 —S—R 2 and R 1 and R 2 are each independently selected from the group consisting of hydrogen, an alkyl, an alkenyl, an alkynyl, and an aryl.
10. A method comprising:
in a gas stripper unit, stripping a sour gas with a sulfur-lean amine, wherein hydrogen sulfide transfers from the sour gas to the sulfur-lean amine resulting in a treated gas and a sulfur-rich amine;
in a mercury removal unit, removing mercury from a mercury-containing hydrocarbon liquid by contacting the sulfur-rich amine with the mercury-containing hydrocarbon liquid to transfer mercury from the mercury-containing hydrocarbon liquid to the sulfur-rich amine, thereby resulting in a mercury loaded amine and a treated hydrocarbon liquid;
bypassing the mercury removal unit with a portion of the sulfur-rich amine and directing the portion of the sulfur-rich amine into a regeneration unit;
in the regeneration unit, desorbing sulfur and mercury from a combination of the portion of the sulfur-rich amine and the mercury loaded amine; and
recycling the sulfur-lean amine by directing it from the regeneration unit to the gas stripper unit.
11. The method according to claim 10 , wherein the sulfur-rich amine contains at least 8500 parts per million by weight of the hydrogen sulfide.
12. The method according to claim 10 , wherein the sulfur-rich amine includes the hydrogen sulfide with at least one of monoethanolamine, diethanolamine, triethanolamine, diglycolamine, and monodiethanolamine.
13. The method according to claim 10 , wherein the sulfur-rich amine includes the hydrogen sulfide with diethanolamine, the mercury-containing hydrocarbon liquid and the sulfur-rich amine are contacted while at a temperature of at least 70° C., and the sulfur-rich amine contains at least 8500 parts per million by weight of the hydrogen sulfide.