| 摘要 |
Ethane and other hydrocarbons of higher boiling point are separated as a liquid from natural gas to leave a gas consisting principally of methane for delivery to a pipeline. The natural gas is passed in countercurrent heat exchange with the liquid product and with the pipeline gas to cool the natural gas to a temperature at which a major part of the ethane is condensed. The condensed ethane and higher boiling point hydrocarbons are separated from uncondensed vapors in the natural gas and the vapors are expanded to a low pressure and delivered into the upper end of a fractionating tower. The condensate is expanded to the same pressure and introduced into the fractionating tower at a midpoint thereof. Gases discharged overhead from the fractionating tower constitute the pipeline gas that is returned to the heat exchanger for countercurrent heat exchange with the natural gas. The liquid hydrocarbons withdrawn from the lower end of the fractionating tower are returned to the heat exchanger for heat exchange with the natural gas to cool the natural gas and to supply heat to vaporize a portion of such liquid products which are returned to the fractionating tower. That part of the liquid product that is not returned to the fractionating tower is compressed, cooled and delivered from the system.
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