Application of Novel Compressor/Driver Configuration in the Optimized Cascade® Process

Angola LNG Limited licenses and is completing detailed engineering using the ConocoPhillips Optimized Cascade® Process in the first gas liquefaction facility to be built in Angola. The Optimized Cascade® Process is a well proven liquefaction technology with forty years of operating experience. The technology is currently employed at several operating sites. Most liquefaction facilities using the Optimized Cascade® Process have so far utilized Frame 5 series gas turbines as compressor drivers, while one facility in Australia utilizes the LM2500+ aeroderivative gas turbines. The Angola LNG Project utilizes GE Frame 6 and Frame 7 gas turbine drivers with the Optimized Cascade® Process in a unique way that delivers cost improvements for 5+ MMTPA plants while still maintaining the operating advantages of the two-trains-in-one reliability. Single shaft Frame 6 and Frame 7 gas turbine drivers have been used for many years at several locations with other liquefaction technologies and single shaft Frame 5 machines have been in service for four decades in the Cascade® Process at the Kenai liquefaction facility in Alaska. The Angola LNG Project has re-packaged and applied lessons learned associated with these well proven liquefaction control technologies, equipment and operations in a unique way resulting in a first-of-its-kind refrigeration compression design. The refrigeration compression design of the Angola LNG Project utilizes a combined propane and ethylene compressors configuration on a single shaft enabling the plant to use only four drivers to produce a nominal 5.2 MMTPA. The majority of Optimized Cascade® applications employ six drivers and produce between 3 to 3.7 MMTPA. To date, the only 5+ MMTPA Optimized Cascade® plant employs 8 drivers. The string test of this unique compressor/driver configuration was successfully completed recently. A summary of the string test will be presented in this paper.