	US 12,111,102 B2
	Mixed refrigerants in LNG cascade
Paul Davies, Housto, TX (US); James Lee Harris, Jr., Houston, TX (US); Emery Jay Thomas, Houston, TX (US); and Gregg Sapp, Houston, TX (US)
Assigned to CONOCOPHILLIPS COMPANY, Houston, TX (US)
Filed by CONOCOPHILLIPS COMPANY, Houston, TX (US)
Filed on Nov. 11, 2022, as Appl. No. 18/054,635.
Application 18/054,635 is a continuation of application No. 14/085,372, filed on Nov. 20, 2013, granted, now 11,885,561.
Claims priority of provisional application 61/733,293, filed on Dec. 4, 2012.
Prior Publication US 2023/0204284 A1, Jun. 29, 2023
Int. Cl. F25J 1/00 (2006.01); C09K 5/04 (2006.01); F25J 1/02 (2006.01)

CPC F25J 1/0022 (2013.01) [C09K 5/042 (2013.01); C09K 5/045 (2013.01); F25J 1/0062 (2013.01); F25J 1/0097 (2013.01); F25J 1/0256 (2013.01); F25J 1/0278 (2013.01); C09K 2205/126 (2013.01)]

22 Claims

1. An improved cascade process for liquifying natural gas (LNG), wherein a cascade process for making LNG uses a first pure propane refrigerant cycle, a second pure ethane refrigerant cycle, and a third pure methane refrigerant cycle, the improvement comprising making LNG in a modified-cascade process comprising:

a. a first cycle using a first azeotropic mixed refrigerant comprising an azeotropic mix of 75-90% propane and 10-25% fluorinated olefin having a boiling point within 20° F. of pure propane;

b. a second cycle using a second azeotropic mixed refrigerant comprising an azeotropic mix of 75-90% ethane and 10-25% fluorinated olefin having a boiling point within 20° F. of pure ethane;

c. a third cycle using a third azeotropic mixed refrigerant comprising an azeotropic mix of 75-95% methane and 5-25% fluorinated olefin having a boiling point within 20° F. of pure methane,

d. wherein said modified-cascade process lowers a risk of vapor cloud explosion as compared to said cascade process.