Apparatus and method for optimizing a natural gas liquefaction train having a nitrogen cooling loop
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Solution Overview
Problem
Manual control of liquefied natural gas facilities is sub-optimal due to numerous process variables, leading to production losses and monetary losses, as existing control systems fail to efficiently manage nitrogen cooling loops in natural gas liquefaction trains.
Innovation Solution
An apparatus and method utilizing a processor and memory to determine adjustments for manipulated variables associated with a nitrogen cooling loop, such as nitrogen flow and compressor operation, to control controlled variables like LNG rundown temperature and calorific value, employing model predictive control to optimize the operation of natural gas liquefaction trains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual control is used to adjust operating variables, then operators can make periodic adjustments, but control is sub-optimal resulting in production loss
Solution Approach 1:
The control system performs self-optimization by automatically adjusting manipulated variables based on process models and real-time data, eliminating the need for manual operator intervention while maintaining optimal production levels. The system serves itself by continuously determining optimal operating conditions and implementing adjustments without human involvement.
Solution Approach 2:
The patent replaces manual mechanical control operations with an automated computational control system that uses process models and algorithms to determine optimal manipulated variable adjustments, substituting human operator actions with automated electronic control mechanisms.
2Adaptability or versatility
If the number of process variables is large, then comprehensive control is possible, but control difficulty increases
Solution Approach 1:
The control system segments the complex control problem by dividing it into manageable components: process models for different sections of the liquefaction train, distinct controlled variables groups, and manipulated variables groups. This segmentation allows the system to handle large numbers of variables through modular modeling and systematic control strategies.
Solution Approach 2:
The patent introduces process models as intermediary elements that mediate between the large number of process variables and the control decisions. These models serve as intermediaries that simplify the relationship between manipulated and controlled variables, making the control system manageable despite the large number of underlying process variables.
3Productivity
If automated control is implemented, then production optimization is achieved, but system complexity increases
Solution Approach 1:
The control system achieves universality by implementing a multi-functional automated control architecture that can handle multiple controlled variables, adjust multiple manipulated variables, and optimize various aspects of liquefaction train operation within a single integrated system, reducing the need for multiple separate control systems.
Solution Approach 2:
The patent utilizes parameter changes in the process models to adapt the control system to different operating conditions. By dynamically adjusting model parameters based on real-time process data, the system maintains optimal control without requiring complex reconfiguration, achieving adaptability through parameter adjustment rather than structural complexity.
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 enhances the efficiency of natural gas liquefaction trains by optimizing nitrogen cooling loops, reducing production losses and improving operational efficiency through automated control, allowing for maximum LNG output with minimal energy consumption.
Implementation Method 1
a nitrogen cooling loop in the natural gas liquefaction train
Implementation Method 2
adjust operation of a compressor associated with the nitrogen cooling loop to adjust the nitrogen flow
Data Source
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AI summary
A natural gas liquefaction train (100, 100a-100n) includes a nitrogen cooling loop. A controller (208a-208n, 300) is provided for controlling one or more controlled variables by adjusting one or more manipulated variables. The one or more manipulated variables may include a nitrogen flow associated with the nitrogen cooling loop in the natural gas liquefaction train. The controller could adjust the nitrogen flow by adjusting operation of a compressor (178) associated with the nitrogen cooling loop. The one or more controlled variables may include a rundown temperature of liquefied natural gas exiting the nitrogen loop and/or a calorific or heating value of the liquefied natural gas exiting the nitrogen loop. A second controller (206a-206n) could control other aspects of the natural gas liquefaction train, such as by controlling a mass flow rate of a feed gas in the natural gas liquefaction train.