LNG PRODUCTION WITH NITROGEN REMOVAL Russian patent published in 2022 - IPC F25J1/00 F25J3/02 

FIELD: cryogenic technology.

SUBSTANCE: invention relates to cryogenic technology. A method and system for liquefying the supplied natural gas stream and removing nitrogen from it are proposed. The natural gas stream is cooled and liquefied in the main heat exchanger due to indirect heat exchange with the first refrigerant, thus forming the first LNG stream. The first LNG stream is expanded and fed into the distillation column. The flow of nitrogen-depleted bottom liquid is diverted from the distillation column to form a second, nitrogen-depleted LNG stream. The flow of nitrogen-enriched steam of the upper fraction is heated in the upper heat exchanger. They are compressed, liquefied due to indirect heat exchange with the first refrigerant, supercooled in the upper heat exchanger due to indirect heat exchange with nitrogen-enriched steam of the upper fraction and the recirculating flow formed from the first part of the heated steam of the upper fraction is expanded and fed it into the distillation column. The upper heat exchanger is separated from the main heat exchanger, and the entire cooling capacity for the upper heat exchanger is provided by heating the flow of nitrogen-enriched steam of the upper fraction.

EFFECT: invention makes it possible to simplify the liquefaction system.

20 cl, 5 dwg