Natural gas deacidizing method
AssigneeInstitut Francais du Petrole
InventorsAlexandre Rojey, Fabrice Lecomte, Eric Lemaire
Life of this patent
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Abstract
The natural gas is successively contacted in column CA with a relatively methanol-rich solvent flowing in through line 4, then with a relatively poor solvent flowing in through line 9. The acid gas-containing solvent recovered through line 3 at the bottom of column CA is expanded through valves V1 and V2 to release acid gases through line 6. A fraction of the expanded solvent is distilled in column CR. The regenerated solvent obtained at the bottom of column CR is sent to the top of column CA through line 9. A second fraction of the expanded solvent is mixed with a solvent drawn off from column CR at an intermediate point between the bottom and the top of this column. This mixture of solvents is sent through line 4 into column CA.
Claims10
A method of deacidizing a natural gas containing acid gases wherein the following stages are carried out:
- (a) contacting the natural gas with a first solvent containing methanol, water and an amine, obtained in stage e), and with a third solvent containing acid gases obtained in stage b) so as to obtain a methanol-containing gas and an acid gas-containing solvent,
- (b) contacting the gas obtained in stage a) with a second solvent containing methanol, water and an amine, obtained in stage d), so as to obtain a gas partly freed of acid gases and the third solvent containing acid gas,
- (c) expanding the acid gas-containing solvent obtained in stage a) so as to release acid gases and to obtain a partly regenerated solvent,
- (d) distilling in a distillation column a first fraction of the partly regenerated solvent obtained in stage c) so as to obtain a gas phase containing acid gases and the second solvent,
- (e) mixing a second fraction of the partly regenerated solvent obtained in stage c) with a fourth solvent drawn off at a point of the distillation column located between the bottom and the top of the distillation column so as to obtain the first solvent, the draw-off point being determined for the proportion by mole of methanol of the first solvent to be higher than that of the second solvent.
A method as claimed in claim 4, wherein the second solvent contains less than 1% by weight of methanol.
Dependencies are inferred from the claim text.