| 摘要 |
A stream of natural gas, which is rich in C5+ hydrocarbons and may be wet or dry or sweet or sour, is extracted in two stages with a physical solvent. In the first stage, a major portion of the solvent, containing up to an equilibrium amount of C5+ hydrocarbons, removes substantially all of the water and the C2+ hydrocarbons. In the second stage, the partially stripped natural gas is countercurrently extracted with a lean-and-dry minor portion of the solvent which contains less than 1% by weight of water and less than 1% by volume of hydrocarbons. The residue natural gas, which is then sent to a pipeline, contains less than 7 pounds of water per million standard cubic feet. The rich solvent is flashed to atmospheric pressure in at least two stages, forming a methane-rich vapor portion which is suitably recycled to the first extraction, a methane-poor vapor portion, and a flashed solvent containing up to equilibrium amounts of C5+ hydrocarbons. The methane-poor vapor portion is compressed, cooled, and condensed to form a liquid stream which is selectively stripped of C1, C1+C 2, C1+C2+C3 or C1+C2+C3+C4 to form a liquid hydrocarbon product of selected composition based on market economics. A slipstream of the flashed solvent, containing the amount of water picked up from the natural gas stream and amounting to less than 25% by weight of the flashed solvent, is all that needs to be regenerated to form the lean-and-dry minor portion. |
