System and method for removal of heavy metal ions from a rich hydrate inhibitor stream
Method and system for removal of heavy metal ions from a rich hydrate inhibitor stream, wherein the method comprises a) adding a selective heavy metal reactant to the rich hydrate inhibitor stream, forming a fluid stream comprising heavy metal salt particles, b) separating the obtained fluid stream in three streams a hydrocarbon stream, a recovered rich hydrate inhibitor stream, and a slurry comprising the heavy metal salt particles, c) separating remaining hydrate inhibitor from the slurry thereby obtaining a concentrated rest comprising the heavy metal salt particles.
1. A method for removal of heavy metal ions from a rich hydrate inhibitor stream, wherein the method comprises:
a) adding a selective heavy metal reactant to the rich hydrate inhibitor stream, forming a fluid stream comprising heavy metal salt particles,
wherein the selective heavy metal reactant is a sulphide;
b) separating the obtained fluid stream into three streams: a hydrocarbon stream, a recovered rich hydrate inhibitor stream, and a slurry comprising the heavy metal salt particles; and
c) separating remaining hydrate inhibitor from the slurry thereby obtaining a concentrated rest comprising the heavy metal salt particles.
2. The method according to claim 1 , wherein the separation in step b) is performed in a disc stack centrifuge.
3. The method according to claim 1 , wherein the method comprises regulating the pH of the rich hydrate inhibitor stream to between 6 and 8.
4. The method according to claim 1 , wherein the method comprises regulating the temperature of the rich hydrate inhibitor stream to below 50° C.
5. The method according to claim 1 , wherein the heavy metal is selected from the group consisting of mercury, cadmium, lead, chromium, cobalt, arsenic, nickel, manganese, and copper.
6. The method according to claim 1 , wherein the method comprises combining the remaining hydrate inhibitor with the recovered rich hydrate inhibitor stream.
7. The method according to claim 1 , wherein the method further comprises downstream precipitation and removal of divalent cation salts from the recovered rich hydrate inhibitor stream.
8. The method according to claim 1 , wherein the sulphide is Na 2 S.
9. The method according to claim 1 , wherein the method further comprises adding a flocculent to the rich hydrate inhibitor stream.
10. The method according to claim 1 , wherein the hydrate inhibitor is mono-ethylene glycol (MEG).