Method to Produce LNG at Gas Pressure Letdown Stations in Natural Gas Transmission Pipeline Systems

摘要

There is described a method to produce LNG at gas pressure letdown stations. A high pressure gas stream is pre-cooled, dewatered, and then divided into two streams: a diverted LNG production stream (LNG stream) and a gas to end users stream (User stream). Carbon dioxide is removed from the LNG stream and the LNG stream is compressed. The LNG stream is then precooled by passing through one or more heat exchangers. Hydrocarbon condensate is removed from the LNG steam by passing the LNG stream through a first Knock Out drum. The LNG stream is then depressured by passing through a JT valve to depressurize the gas vapour exiting the first Knock Out drum and discharge it into a second Knock Out drum where the LNG is captured.

主权项

1. A method to produce LNG at gas pressure letdown stations, comprising:
pre-cooling a high pressure gas stream entering a gas pressure letdown station; dewatering the high pressure natural gas stream after pre-cooling; splitting the dewatered high pressure natural gas stream into two streams: a diverted (LNG production) stream and a gas to end users stream; removing carbon dioxide from the diverted (LNG production) stream; compressing the diverted (LNG production) stream, which has been dewatered and had carbon dioxide removed; precooling the diverted (LNG production) stream by passing the diverted (LNG production) stream through one or more heat exchanger downstream of the compressor; removing hydrocarbon condensate from the diverted (LNG production) steam by passing the diverted (LNG production) stream through a first Knock Out drum so that the diverted (LNG production) stream exiting the first Knock Out drum is a gas vapour stream; depressurizing the diverted (LNG production) stream by passing the diverted (LNG production) stream through a JT valve to depressurize the gas vapour exiting the first Knock Out drum and discharge it into a second Knock Out drum; and removing LNG from the diverted (LNG production) stream in second Knock Out drum.