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

An apparatus for producing a nitrogen-depleted LNG product, the apparatus comprising:

• a main heat exchanger having cooling passages for receiving a natural gas feed stream and passing said stream through the heat exchanger to cool the stream and liquefy all or a portion of the stream so as to produce a first LNG stream, and for receiving a compressed recycle stream composed of nitrogen-enriched natural gas vapor and passing said stream through the heat exchanger to cool and at least partially liquefy the stream so as to produce a first at least partially liquefied nitrogen-enriched natural gas stream, wherein said cooling passages are arranged so as to pass the compressed recycle stream through the heat exchanger separately from and in parallel with the natural gas feed stream;
• a refrigeration system for supplying refrigerant to the main heat exchanger for cooling the cooling passages;
• a first separation system, in fluid flow communication with the main heat exchanger, for receiving, 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;
• a compressor, in fluid flow communication with the first separation system and main heat exchanger, for receiving the recycle stream, compressing the recycle stream to form the compressed recycle stream, and returning the compressed recycle stream to the main heat exchanger;
• and
• a second separation system, in fluid flow communication with the main heat exchanger, for receiving, expanding, partially vaporizing and separating the first at least partially liquefied nitrogen-enriched natural gas stream to form a nitrogen-rich vapor product.