Process Control Operating Envelope Using Proxy Limit Variables
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Solution Overview
Problem
Industrial process control and automation systems face challenges in accurately defining and managing the operating envelope of industrial processes due to shifts over time caused by equipment changes, impurities, and mechanical wear, which are often estimated rather than quantified in real-time.
Innovation Solution
The use of proxy limit variables to define an operating envelope in real-time or near real-time through advanced process control, allowing for the identification and presentation of maximum and minimum values in a graphical user interface, enabling managers and operators to understand and manage equipment limits effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If operating envelope is defined based on intuition or past experience, then decision-making speed is improved, but accuracy and validity for current operations deteriorates
Solution Approach 1:
The system creates a digital replica (virtual model) of the industrial process that copies the complex relationships between process variables. This virtual model can be queried rapidly to obtain accurate operating envelope definitions without requiring real-time physical experimentation, thus providing both speed and accuracy.
Solution Approach 2:
The system pre-calculates and stores operating envelope definitions across the full range of possible process conditions before they are needed. When an upset or event occurs, the pre-computed information is immediately retrieved and presented to operators, eliminating the need for real-time calculation while ensuring accuracy.
2Measurement precision
If real-time operating envelope calculation is implemented, then operating envelope accuracy is improved, but system complexity and computational requirements worsen
Solution Approach 1:
The system performs comprehensive operating envelope calculations in advance during normal operations and stores the results. When upsets occur, it retrieves pre-computed information rather than performing new calculations, significantly reducing computational complexity while maintaining accuracy.
Solution Approach 2:
The system divides the operating envelope calculation into separate virtual models for different process units or variables. Each virtual model handles specific calculations independently, reducing the complexity of any single computational task while providing comprehensive coverage.
3Measurement precision
If comprehensive process variable monitoring is implemented, then operating envelope definition accuracy is improved, but data processing requirements and system resource usage worsen
Solution Approach 1:
The system extracts and focuses only on the critical process variables that define the operating envelope, separating them from the full set of monitored variables. This reduces the amount of data that needs to be processed and stored while maintaining the accuracy needed for safe operations.
Solution Approach 2:
The system pre-identifies and stores the relationships between critical process variables and operating limits before upsets occur. During events, only this extracted critical information needs to be accessed and presented, minimizing real-time computational resource usage.
Data Source
AI summary
A method includes identifying one or more proxy limit variables to be used to define an operating envelope associated with an industrial process controller. The industrial process controller is associated with a number of process variables including the proxy limit variable(s). The method also includes maximizing and minimizing at least one of the proxy limit variable(s). The method further includes presenting maximum and minimum values of the at least one of the proxy limit variable(s) as the operating envelope in a graphical user interface to at least one user. A single proxy limit variable could be used, and maximum and minimum values of the single proxy limit variable can be presented in a one-dimensional representation of the operating envelope. Multiple proxy limit variables could also be used, and maximum and minimum values of the proxy limit variables can be presented in a multi-dimensional representation of the operating envelope.