Optimal operation of a mixed fluid cascade LNG plant

Studies on the operation of complex vapour compression cycles, like the one used for the production of liquefied natural gas (LNG), are not widely reported in the open literature. This is a bit surprising, considering the large amount of work that has been put into optimizing the design of such processes. It is important that the process is operated close to optimum to fully achieve the maximum performance in practice. These are possibilities for savings, both due to (a) identifying the optimal point of operation, and (b) selecting the controlled variables such that the optimal operation depends weakly on disturbances. In this paper we study the mixed fluid casade (MFC) LNG process developed by The Statoil Linde Technology Alliance . We study the degrees of freedom and how to adjust these to achieve optimal steadystate operation.