Mixed Refrigerant Composition Control for Continuous LNG Optimization
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Solution Overview
Problem
Liquefied natural gas (LNG) plants typically operate sub-optimally due to fixed mixed refrigerant (MR) composition, leading to reduced production and increased costs, as changes in ambient temperature and feedstock composition cannot be accommodated during normal operation.
Innovation Solution
A system and method for continuously adjusting the composition of the MR fluid in a liquefaction system by separating and reintroducing heavy and light components, allowing for real-time optimization of the MR fluid's pressure and flow rate to match varying operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mixed refrigerant composition is changed to optimize plant performance, then efficiency and production are improved, but the plant must be shut down for composition changes
Solution Approach 1:
The patent implements a dynamic mixed refrigerant composition adjustment system that allows continuous modification of refrigerant properties during plant operation. Sensors monitor temperature, pressure, and flow rate in real-time, and a control system automatically adjusts the composition by blending different refrigerant components, eliminating the need for shutdowns while optimizing LNG production
Solution Approach 2:
The system changes physical parameters of the mixed refrigerant (composition, temperature, pressure) dynamically during operation. By continuously adjusting the ratio of light to heavy refrigerant components based on real-time operating conditions, the system optimizes heat transfer efficiency and maintains peak productivity without interruption
2Reliability
If the mixed refrigerant composition is held constant during operation, then system stability is maintained, but the plant performs sub-optimally under varying conditions
Solution Approach 1:
The patent implements a closed-loop feedback control system where sensors continuously monitor operating conditions (ambient temperature, feedstock composition, pressure, flow rate) and transmit data to a control system. The control system automatically adjusts the mixed refrigerant composition in response to deviations from optimal performance, maintaining both system stability and high productivity under varying conditions
Solution Approach 2:
The system performs self-adjustment of refrigerant composition based on real-time condition monitoring. The control system automatically modifies the refrigerant blend without external intervention, allowing the plant to adapt to changing ambient temperatures and feedstock compositions while maintaining optimal LNG production and system stability
3Productivity
If the mixed refrigerant composition is optimized for one set of operating conditions, then performance is maximized at those conditions, but the plant cannot accommodate changes in ambient temperature or feedstock composition
Solution Approach 1:
The patent creates a multi-functional mixed refrigerant system that can adapt to various operating conditions. The system uses a blend of light and heavy refrigerant components that can be dynamically adjusted to serve multiple functions: cooling during hot ambient conditions, maintaining efficiency during cold conditions, and adapting to different feedstock compositions, making the plant universally effective across diverse operating scenarios
Solution Approach 2:
The system transitions from a static, single-optimization-point design to a dynamic, multi-condition optimization system. Real-time sensors detect changes in ambient temperature and feedstock composition, and the control system continuously adjusts the refrigerant composition to maintain optimal performance across varying conditions, enhancing both productivity and adaptability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach maximizes efficiency, production, and profitability of LNG production by enabling continuous optimization of the MR fluid composition, reducing operating costs and improving system performance across different ambient temperatures and feedstock compositions.
Implementation Method 1
a condenser configured to condense at least a portion of the MR fluid to form a liquid-vapor mixture
Implementation Method 2
a heat exchanger configured to receive the MR fluid that is in circulation, and configured to receive a methane-containing vapor such that heat can be transferred from the methane-containing vapor to the MR fluid to thereby condense the methane-containing vapor into a liquefied natural gas (LNG)
Data Source
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AI summary
Systems and methods are provided for adjusting a composition, pressure, and/or flow rate of a mixed refrigerant (105,305) (MR) fluid in a liquefaction system to provide refrigeration to natural gas (NG) feedstock to produce liquefied natural gas (LNG). The MR fluid (105,305) that is in circulation within a liquefaction system can include heavy components and light components. During LNG production, heavy components and/or light components of the MR fluid (105,305) can be selectively removed from, and reintroduce into the MR fluid (105,305), thereby altering the composition of the remaining MR fluid (105,305) in circulation. Adjusting the composition of the MR fluid (105,305) in circulation within a liquefaction system can allow the system to be optimized to maximize efficiency, LNG production, and or profitability while the system is in operation.