Integrated Nitrogen Removal in the Production of Liquefied Natural Gas Using Dedicated Reinjection Circuit

摘要

A method and apparatus for liquefying a natural gas feed stream and removing nitrogen therefrom to produce a nitrogen-depleted LNG product, in which a natural gas feed stream is passed through main heat exchanger to produce a first LNG stream, which is separated to form a nitrogen-depleted LNG product and a recycle stream composed of nitrogen-enriched natural gas vapor, and in which the recycle stream is passed through main heat exchanger to produce a first LNG stream, separately from and in parallel with the natural gas feed stream, to produce a first at least partially liquefied nitrogen-enriched natural gas stream that is separated to provide a nitrogen-rich vapor product.

主权项

1. A method for producing a nitrogen-depleted LNG product, the method comprising:
(a) passing a natural gas feed stream through a main heat exchanger to cool the natural gas feed stream and liquefy all or a portion of said stream, thereby producing a first LNG stream; (b) withdrawing the first LNG stream from the main heat exchanger; (c) expanding, partially vaporizing and separating the first LNG stream, or an LNG stream formed from part of the first LNG stream, to form a nitrogen-depleted LNG product and a recycle stream composed of nitrogen-enriched natural gas vapor; (d) compressing the recycle stream to form a compressed recycle stream; (e) passing the compressed recycle stream through the main heat exchanger, separately from and in parallel with the natural gas feed stream, to cool the compressed recycle stream and at least partially liquefy all or a portion thereof, thereby producing a first at least partially liquefied nitrogen-enriched natural gas stream; (f) withdrawing the first at least partially liquefied nitrogen-enriched natural gas stream from the main heat exchanger; and (g) expanding, partially vaporizing and separating the first at least partially liquefied nitrogen-enriched natural gas stream to form a nitrogen-rich vapor product.