The "two-trains-in-one" concept was developed in the 1960s for the facility in Kenai, Alaska, due to the plant’s remote location and the need for high on-stream availability, superior flexibility, and exceptional robustness. The concept is simple and straightforward. Plants are configured so equipment with higher maintenance needs such as gas turbines and compressors are duplicated, while more reliable components like air fin coolers and brazed aluminum heat exchangers are not duplicated.
The design has been proven in over four decades of operation at Kenai with an overall plant production efficiency exceeding 95 percent and gas turbine section reliability in excess of 99 percent. Building on this success, subsequent Optimized Cascade® Process plants have incorporated the two-trains-in-one concept.
Two-trains-in-one Advantages
Advantages of the two-trains-in-one design include:
High Production Efficiency — Up to 60 percent of design capacity possible even with one-half of compressor power off-line.
Wide Range of Capacity Flexibility
— Able to operate from near zero to 100 percent of design with sustainable production as low as 10 percent for extended periods of time.
Maintenance Flexibility — Opportunistic maintenance can be performed during periods of low production to extend the interval between turnarounds. In some cases, major overhaul of an adjacent gas turbine/compressor has been accomplished while the plant continues in operation.
Optimize Plant Efficiency
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Plant and equipment efficiencies can be maximized by adjusting the number and mix of gas turbines/compressors online during periods of lower than normal production rates.
Continuous Improvement
Over time and in subsequent facility installations around the world, the ConocoPhillips Optimized Cascade Process has undergone continued improvement, but always holding constant to the reliability and flexibility advantages of the "
two-trains-in-one"
design. Some of these improvements include:
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Load balancing of refrigeration circuits to optimize available horsepower
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Development of the open methane refrigeration loop to maximize thermal efficiency
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Cold box configuration optimized to improve the process and reduce the plot area
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Integrated LPG and condensate recovery within the liquefaction unit to reduce total unit cost
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First application of highly efficient aeroderivative gas turbines in LNG Liquefaction
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Waste heat recovery integration
Customer Advantages
The core design element and advantage of the ConocoPhillips Optimized Cascade Process is the "
two-trains-in-one"
configuration. This design provides:
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Greater flexibility and potential capital cost savings through competitive equipment bidding
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Ease of start-up, shutdown and operation
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Unmatched operating availability, with up to 80 percent capacity maintained during routine maintenance
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Full range production flexibility from near zero to 100 percent of design production
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High thermal efficiency