When Advanced Process Control (APC) is needed?
The common objective of advanced process control (APC) is to find a way to manage complex interactions within a process better than primary process control. Primary process control works best when one variable and one actuator are related. However, often moving one actuator affects several variables at the same time. This is where primary process control methods lose some effectiveness and using advanced process control method is required.
Where advanced process control (APC) is needed?
When considering advanced process control (APC) deployments, some are better candidates than others. Four typical elements can be used for advanced process control technology decision: The process is highly interacted, has many constraints, has high energy costs and/or has got high product value recovery.
What is economic drive of advanced process control (APC)?
The optimization algorithm with its objective function is the most frequently economic drive of advanced process control (APC). Th idea is to balance all the interacting elements in a way to achieve the most desirable outcomes laid out by plant management. Depending on the type of technology, and how it is configured, the most efficient economic driver should be something like:
- Increase feed to the plant.
- Create higher-value products.
- Reduce energy consumption.
Which advanced process control (APC) to install?
Advanced process control (APC) systems are typically installed separately from the installed distributed control system (DCS). Often this is still a logical choice since the system equipment can be selected from any vendor and does not need to be from the same DCS hardware provider.
More current DCS platforms often have the capability to support embedded APC functions, which is particularly useful for smaller process units. This is certainly the simplest from an implementation standpoint and typically makes it the most transparent to the operators, but requires that you have a relatively DCS recent system to find such APC functionality. Additionally, the same DCS processors now have to do the APC related calculations along with normal process control duties, and this can compromise responsiveness depending on the complexity of the system.
Author: Peter Welander, Control Engineering
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