Process for the purification of gaseous mixtures containing mercaptans and other acid gases
The invention relates to a process for the purification of a gaseous mixture containing mercaptans and other acid gases comprising a stage of bringing said gaseous mixture into contact with an absorbent solution comprising an alkanolamine, a C 2 -C 4 thioalkanol and water.
1. Purification process for a gaseous mixture containing acid gases comprising a stage of bringing said gaseous mixture into contact with an absorbent solution comprising an alkanolamine, thiodiethylene glycol and water.
2. Purification process according to claim 1 , in which the gaseous mixture comprises mercaptans and other acid gases.
3. Purification process according to claim 1 or 2 in which said gaseous mixture is natural gas.
4. Purification process according to claim 2 in which the mercaptan or mercaptans comprise methyl mercaptan and/or ethyl mercaptan.
5. Purification process according to claim 1 , in which the acid gases comprise hydrogen sulphide and/or carbon dioxide and/or carbonyl sulphide.
6. Purification process according to claim 1 in which the alkanolamine is diethanolamine.
7. Purification process according to claim 1 in which the absorbent solution comprises:
20 to 60% by mass of diethanolamine;
20 to 60% by mass of water; and
10 to 40% by mass of thiodiethylene glycol.
8. Purification process according to claim 1 in which the absorbent solution comprises:
30 to 45% by mass of diethanolamine;
30 to 50% by mass of water; and
15 to 30% by mass of thiodiethylene glycol.
9. Purification process according to claim 1 in which the absorbent solution comprises:
40% by mass of diethanolamine;
40% by mass of water; and
20% by mass of thiodiethylene glycol.
10. Purification process according to claim 1 implemented in an absorber at a temperature comprised between 40 and 100° C.
11. Purification process according to claim 1 in which the gaseous mixture is brought into contact with the absorbent solution at a gaseous mixture flow rate comprised between 0.23 10 6 Nm 3 /day and 56 10 6 Nm 3 /day and at an absorbent solution flow rate comprised between 800 m 3 /day and 50000 m 3 /day.
12. Purification process according to claim 1 also comprising a stage of regeneration of the absorbent solution loaded with mercaptans and other acid gases at a regeneration pressure comprised between 0 and 20 bar and at a temperature comprised between 100 and 140° C.
13. Purification process according to claim 1 , for reducing the concentration of mercaptans contained in the gaseous mixture to a value of less than 5 μm.
14. Purification process according to claim 1 for reducing the concentration of hydrogen sulphide contained in the gaseous mixture to a value of less than 4 ppm.
15. Purification process according to claim 1 for reducing the concentration of carbon dioxide contained in the gaseous mixture to a value of less than 50 ppm.
16. Purification process according to claim 1 for reducing the concentration of carbonyl sulphide contained in the gaseous mixture to a value of less than 1 ppm.
17. Absorbent solution comprising:
20 to 60% by mass of an alkanolamine;
20 to 60% by mass of water; and
10 to 40% by mass of thiodiethylene glycol.
18. Absorbent solution according to claim 17 comprising:
30 to 45% by mass of an alkanolamine;
30 to 50% by mass of water; and
15 to 30% by mass of thiodiethylene glycol.
19. Absorbent solution according to claim 17 or 18 , in which the alkanolamine is diethanolamine.
20. Purification process for a gaseous mixture containing acid gases comprising a stage of bringing said gaseous mixture into contact with an absorbent solution comprising an alkanolamine, ethylene dithioethanol and water.
21. Purification process according to claim 20 , in which the gaseous mixture comprises mercaptans and other acid gases.
22. Purification process according to claim 20 or 21 in which said gaseous mixture is natural gas.
23. Purification process according to claim 22 , in which the mercaptan or mercaptans comprise methyl mercaptan and/or ethyl mercaptan.
24. Purification process according to claim 20 , in which the acid gases comprise hydrogen sulphide and/or carbon dioxide and/or carbonyl sulphide.
25. Purification process according to claim 20 in which the alkanolamine is diethanolamine.
26. Purification process according to claim 25 in which the absorbent solution comprises:
20 to 60% by mass of diethanolamine;
20 to 60% by mass of water; and
10 to 40% by mass of ethylene dithioethanol.
27. Purification process according to claim 25 in which the absorbent solution comprises:
30 to 45% by mass of diethanolamine;
30 to 50% by mass of water; and
15 to 30% by mass of ethylene dithioethanol.
28. Purification process according to claim 25 in which the absorbent solution comprises:
40% by mass of diethanolamine;
40% by mass of water; and
20% by mass of ethylene dithioethanol.
29. Purification process according to claim 20 implemented in an absorber at a temperature comprised between 40 and 100° C.
30. Purification process according to claim 20 in which the gaseous mixture is brought into contact with the absorbent solution at a gaseous mixture flow rate comprised between 0.23 10 6 Nm 3 /day and 56 10 6 Nm 3 /day and at an absorbent solution flow rate comprised between 800 m 3 /day and 50000 m 3 /day.
31. Purification process according to claim 20 also comprising a stage of regeneration of the absorbent solution loaded with mercaptans and other acid gases at a regeneration pressure comprised between 0 and 20 bar and at a temperature comprised between 100 and 140° C.
32. Purification process according to claim 20 , for reducing the concentration of mercaptans contained in the gaseous mixture to a value of less than 5 ppm.
33. Purification process according to claim 20 for reducing the concentration of hydrogen sulphide contained in the gaseous mixture to a value of less than 4 ppm.
34. Purification process according to claim 20 for reducing the concentration of carbon dioxide contained in the gaseous mixture to a value of less than 50 ppm.
35. Purification process according to claim 20 for reducing the concentration of carbonyl sulphide contained in the gaseous mixture to a value of less than 1 ppm.
36. Absorbent solution comprising:
20 to 60% by mass of an alkanolamine;
20 to 60% by mass of water; and
10 to 40% by mass of ethylene dithioethanol.
37. Absorbent solution according to claim 36 comprising:
30 to 45% by mass of an alkanolamine;
30 to 50% by mass of water; and
15 to 30% by mass of ethylene dithioethanol.
38. Absorbent solution according to claim 36 or 37 , in which the alkanolamine is diethanolamine.