MINLP Constraint Grouping for Real-Time Process Optimization
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Solution Overview
Problem
Conventional systems for continuous process optimization, such as those in refineries and petrochemical plants, face inefficiencies due to the complexity and time-consuming nature of Mixed Integer Nonlinear Programming (MINLP) solvers, which are not optimized for processor and memory usage, and require offline case studies for switchable units.
Innovation Solution
Implementing online first-principles simulation techniques in conjunction with a MINLP solver, grouping process units to enforce constraints, allowing for real-time determination of optimal operating states without taking switchable units offline, and using a system with sensors and control systems to manage these units' active and inactive states based on group identifier and complement parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MINLP solvers are used to determine optimal operating states, then optimal solutions can be found in all possible regions, but the calculation process becomes complex and time-consuming
Solution Approach 1:
The patent segments the MINLP problem into two distinct phases: a discrete event simulation phase that handles switchable units and operational constraints, and a continuous optimization phase that handles smooth nonlinear programming. This segmentation allows each phase to be solved with appropriate methods, reducing overall computational complexity and time while maintaining solution optimality.
Solution Approach 2:
The patent performs preliminary discretization of the time horizon and preliminary identification of switchable units and their operational constraints before the main optimization. This preliminary action prepares the problem structure in advance, allowing the solver to focus computational effort on the critical optimization decisions rather than spending time on basic setup and constraint formulation during the solving process.
2Reliability
If conventional MINLP solvers are implemented, then optimal decisions for switchable units can be determined, but the system is not optimized to efficiently use processors and memory
Solution Approach 1:
The patent implements a dynamic solution approach where the optimization problem is reformulated to separate discrete switching decisions from continuous operational parameters. The discrete events are handled through event-driven simulation logic that dynamically adjusts the continuous optimization intervals, allowing the computational system to adapt its resource usage to the actual problem complexity rather than allocating resources for all possible scenarios.
Solution Approach 2:
The patent substitutes the traditional mechanical MINLP solver approach with a hybrid methodology that replaces parts of the mathematical programming mechanism with discrete event simulation logic. This substitution eliminates the need for the solver to handle complex integer constraints and switchable unit logic, reducing computational burden on processors and memory while maintaining accurate determination of optimal switching decisions.
3Measurement precision
If case studies model switchable units offline, then operational constraints can be analyzed, but real-time optimization is not achieved
Solution Approach 1:
The patent enables continuous real-time optimization by formulating the problem to handle both discrete switching events and continuous operational changes within a unified online framework. The discrete event simulation component continuously monitors process conditions and triggers optimization cycles as needed, while the continuous nonlinear programming component continuously adjusts operational parameters. This continuous action eliminates the need to take units offline for case studies while maintaining accurate constraint modeling.
Data Source
AI summary
Real-time dynamic optimization of a process model in an online model-based process control computing environment. A mixed integer nonlinear programming (MINLP) solver utilizes grouping of first-principle model units to implement constraints of the underlying process. A group identifier parameter and a group complement parameter enable the grouping behavior through association with the first-principles model units.


