【正文】 to match the best fit of pressors and drivers available from multiple vendors, the resulting process will have a lower specific power requirement, and could have a lower capital cost than traditional technologies. The DMR process with brazed aluminum heat exchangers shows a unit cost advantage across a broad range of plant capacities and optimizes the tradeoffs of efficiency versus cost for a wide size range (36 MTPA) of 8 plants . EFFICIENT EXPANSION LNG plants have long benefited for profitable expansion trains, typically provided from the same large resource. While the number of discovered large fields available for multitrain development is shrinking, there is still the potential for economical expansion from nearby smaller resources. In many cases these other fields cannot be aggregated into one large project for a variety of reasons: difficulty aligning several mercial interests, waiting on reduced development costs for more difficult resources, or nearfield discoveries identified after the LNG project is underway. For all of these reasons it is desirable to have an easily expandable LNGplant. Treating refrigerant as a utility is a way to maximize the expandability and reliability of a multtrain facility. In this configuration all of the refrigerants that serve the same process function are bined into a single header and delivered as required to the LNG liquefaction sections. The refrigerant as a utility concept can be done with any liquefaction process, but is most suited for dual mixed refrigerants where the refrigerant return pressures can be higher resulting in smaller piping for distribution of refrigerant across the LNG plant. Figure 4 shows one such configuration 9 Treating refrigerant as a utility has several benefits: ? The trains do not necessarily need to be the same size, leading to customizable expansion to match mercial needs. ? All the refrigerants can be retuned to match changes in feed gas position to machinery limits as new gas supplies are brought online. ? Any spare capacity identified by testing after startup can be designed for and utilized during expansion. ? A mixture of gas turbine, steam turbine, and motor drivers can be used giving more flexibility to the driver selection and energy utilization. ? In the event of driver failures, the liquefaction train may be able to turndown instead of shutdown. ? During planned driver maintenance the other drivers can be run at their maximum rates and potentially take advantage of seasonal swings. ? A driver and hence refrigerant supply can be easily spared across the whole plant, increasing plant availability. ? Various cold streams, such as LNGloading vapors, can be effectively integrated into the process scheme to allow the impact of flow fluctuations in these streams to be evenlyspread across all trains for operational stability. With these advantages, a refrigerant as a utility concept could be beneficial to provide 10 options for any project with uncertainty in its expansion possibilities. CONCLUSION In conclusion, a dual mixed refrigerant process with brazed aluminum heat exchangers that treats refrigerant as a utility has the scalability, flexibility and expandability required for the next generation of LNG projects. The system incorporates the guiding principle that capital costs can be minimized by ensuring that there will be multiple vendors or contractors that can supply the equipment or services for the duties required. The design appropriately balances economies of scale against the expense of sole source purchase and results in a more readily scalable configuration. The refrigerant as a utility concept allows for effectively dealing with uncertain expansion plans while providing operational and design flexibility. ExxonMobil can incorporate these process characteristics with these key success factors to ensure a successful project: ? Demonstrated Megaproject management and execution expertise ? Close working relationships with equipment vendors ? Proven startup and missioning experience ? Rigorous technology qualifica