Process for separating hydrocarbon gas constituents utilizing a fractionator
AssigneeMcDermott International, Inc.
InventorHafez K. Aghili
Life of this patent
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Abstract
A process for separating the gas components contained in liquified natural gas wherein a small amount of heavier reflux liquid (propane, butane, pentane, iso-butane and iso-pentane) is recycled to the top of a demethanizer column. This alters its chemical equilibrium causing methane to vaporize in large quantities and to separate from the liquified feed stream. A fractionator receives the heavier demethanized liquid end product from the demethanizer column and through distillation separates the lighter ethanes and propanes from the heavier reflux liquid, a portion of the latter being recycled to the demethanizer column.
Claims12
A process for separating the constituents of a gas stream comprising:
- (a) lowering the temperature of said gas stream;
- (b) supplying said lower temperature gas stream to a high pressure separator, said high pressure separator separating said gas stream into predominantly vapor and predominantly fluid streams;
- (c) lowering the pressure of said predominantly vapor stream;
- (d) supplying said lower pressure vapor stream to an upper region of a demethanizer column;
- (e) lowering the pressure of said predominantly fluid stream;
- (f) supplying said lower pressure fluid stream to said demethanizer column at an elevation below said vapor stream;
- (g) removing cold vapor residue gas from an upper region of said demethanizer column, said vapor residue gas comprising predominantly of methane and other residual light vapors;
- (h) passing said vapor residue gas through at least one heat exchanger to raise the temperature of said vapor residue gas;
- (i) compressing said vapor residue gas for delivery elsewhere;
- (j) removing a cold demethanized product from a lower region of said demethanizer column;
- (k) supplying at least a portion of said demethanized product to a fractionator wherein said fractionator operates as a distillation column;
- (l) separating said demethanized product into an ethane overhead product and a deethanized bottom product;
- (m) removing a generally liquid deethanized product from a lower region of said fractionator;
- (n) drawing off a portion of said deethanized product;
- (o) lowering the temperature of said drawn off product;
- and,
- (p) supplying said lower temperature deethanized product to the top of said demethanizer column whereby the addition of said product alters the chemical equilibrium existing in the top of said demethanizer column thereby enhancing the recovery of ethane constituents at the expense of a small reduction in recovery of propane and heavier constituents.
Dependencies are inferred from the claim text.