US 11,806,639 B2
Pretreatment and pre-cooling of natural gas by high pressure compression and expansion
Yijun Liu, Spring, TX (US); and Fritz Pierre, Jr., Humble, TX (US)
Assigned to ExxonMobil Technology and Engineering Company, Spring, TX (US)
Filed by ExxonMobil Technology and Engineering Company, Spring, TX (US)
Filed on Apr. 17, 2020, as Appl. No. 16/851,718.
Claims priority of provisional application 62/902,459, filed on Sep. 19, 2019.
Prior Publication US 2021/0086099 A1, Mar. 25, 2021
Int. Cl. B01D 1/28 (2006.01); F25J 1/00 (2006.01); F25J 1/02 (2006.01)
CPC B01D 1/2856 (2013.01) [B01D 1/2884 (2013.01); F25J 1/004 (2013.01); F25J 1/0055 (2013.01); F25J 1/0212 (2013.01); F25J 1/0231 (2013.01); F25J 1/0267 (2013.01); F25J 1/0279 (2013.01); F25J 2210/06 (2013.01); F25J 2220/62 (2013.01); F25J 2220/64 (2013.01); F25J 2245/02 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method of producing liquefied natural gas (LNG) from a natural gas stream, the method comprising:
cooling a first portion of the natural gas stream in a first heat exchanger to generate a cooled natural gas stream;
combining the cooled natural gas stream with a second portion of the natural gas stream that has not been cooled to generate a combined natural gas stream;
removing heavy hydrocarbons from the combined natural gas stream to generate a separated natural gas stream;
partially condensing the separated natural gas stream in the first heat exchanger to generate a partially condensed natural gas stream;
separating liquids from the partially condensed natural gas stream to generate a cold pretreated gas stream and a liquid stream;
warming the cold pretreated gas stream in the first heat exchanger to generate a pretreated natural gas stream;
compressing the pretreated natural gas stream in at least one compressor to a pressure of at least 1,500 psia to form a compressed natural gas stream;
cooling the compressed natural gas stream to form a cooled compressed natural gas stream;
expanding, in at least one work-producing natural gas expander, the cooled compressed natural gas stream to a pressure that is less than 2,000 psia and no greater than the pressure to which the at least one compressor compresses the pretreated natural gas stream to form a chilled natural gas stream;
separating the chilled natural gas stream into a refrigerant stream and a non-refrigerant stream;
recycling the refrigerant stream to exchange heat in the first heat exchanger with one or more process streams comprising at least the first portion of the natural gas stream, the separated natural gas stream, and the cold pretreated gas stream to generate a warmed refrigerant stream;
combining the warmed refrigerant stream and the non-refrigerant stream to form a chilled pretreated gas stream; and
liquefying the chilled pretreated natural gas stream to form LNG.