Evolutionary process synthesis for methane liquefaction

This paper focuses on the development of several process alternatives for the liquefaction of natural gas through an evolutionary design approach, taking as a starting point scheme the Linde cycle. Based on thermodynamic considerations for an efficient use and application of the energy involved in the process, four cases of process alternatives are proposed for which the mass and energy balances are estimated through the use of a commercial simulator; the process schemes are evaluated and energetically compared against the minimum thermodynamic work required for the process. An optimal scheme which may reduce the energy consumption to very low levels (equivalent to only about 4 times the minimum work) has been obtained but demanding a more complex structure and more pieces of process equipment. The final selection of the process scheme must be selected among the different processes herein stated after a further economical analysis that includes both the investment and operating costs involved and that allows getting the best cost-effective option.