Are you in tune?

PID tuning for optimum efficiency

Many automated control systems are implemented with smart controllers on complex systems tuned for operating alone or remotely with no need for adjustment. Then entropy happens. Control valves wear, new equipment is installed or old equipment is removed, processes change over time. The original settings you chose are no longer valid for the existing design. Is this a problem?

Consider that your process still produces product as designed. Do you think there is still capacity in it that you cannot reach? Depending on what changes and wear that have happened over the years, and also on how well it was tuned to begin with, you may have at least 25% more capacity in your production system than you realize. Without adding any capital cost, you could drive down your cost per kg across the product lines relatively quickly.

It’s highly likely that your original PID control parameters (proportion, integral, derivative tuning constants) no longer apply to the system that now exists. What does this mean to your business? You likely operate farther from optimum targets due to noise and cycling. You spend less time at target and more time oscillating around it. You wait long periods of time for the process to settle out, if it ever settles out at all. The problem is magnified in nested control loops where one is reliant upon the other such as temperature and level, temperature and flow, or temperature and pressure.

Each type of PID loop needs to be tuned differently due to design constraints. Location of measurements, size of tanks or vessels, and response of lagging systems can all impact the constants significantly. Proper tuning can create stable systems with minimal variation that can run right up close to targets and limits putting your process at optimum efficiency and yielding the largest gains.

I’ve encountered many systems through the years that were running product very profitably, yet still had over 25% capacity hidden within the noise of the control systems. Take a look at your system today and decide if it’s time to bring in an expert to put you at the optimum levels and tune your system.   You can turn Proportional/Integral/Derivative into Payback Increases Dramatically!