This is the first installment of the white paper I introduced in my last blog posting. Just so you don't think I'm too narcissistic, I was actuallly interviewed for this white paper, I am not referring to myself in the third person!
Please enjoy the first way installment **********************
When a process is running, a well-designed automation system can deliver more reliability, repeatability and speed than any human being, according to David Huffman, a manager at ABB with background in chemical and process engineering. The control system can identify when processes change states, and can be programmed to act before those changes become critical.
“Chemical engineers like myself like to think you can put yourself at a steady-state process,” Huffman says. “But trust me, you’re never at a steady state. It’s a misnomer. Processes are always changing.”
Typically, an alarm management system is used to identify such changes, turning over the details of what to do about it to human operators.
“Obviously, there are times when that must happen,” Huffman says. “But there are many other times when nothing is really going wrong. There are some changes that the automation system is capable of identifying and managing if it’s programmed properly.”
As an example, Huffman describes a distillation process that requires the product to move through one of three drying beds. The beds are rotated through primary, secondary and regeneration modes.
“So you’re running full and at about the time you have to switch one bed offline, you find out there’s something wrong with another bed and you can’t put it back into service on time.”
The usual response is slowing down the distillation process while getting the troubled bed fixed. It’s a busy time for operators. “When you start scaling down a distillation tower, it loses efficiency, you lose product quality, and control loops don’t perform well at the reduced-rate condition. The operator is cutting flow rates, changing tower pressure, dealing with overhead systems, boiler systems etc. The more complex the tower is, the worse it gets. And the whole time, alarms are going off continuously.”
But, Huffman continues, “If you know this happens from time to time, you can record what the operator has to do and write a procedure around it for the automation to move the distillation process into a safer mode.”
There is an advantage in speed, which reduces product waste. And automating the routine around best practices means achieving the same results, even if the event occurs when your best operators are off-shift.
Most companies have dozens of examples like this, Huffman says – events that happen often enough to automate, but not often enough to have confidence that every operator is always going to be adequately trained and tested.
Admittedly, improving automation at this level isn’t easy or free. “You have to go through the pain and expense of understanding your routine states, defining them and putting in the programming code.”
Many companies overlook this step when implementing a new automation system. “There’s fatigue involved,” Huffman says.
“The company gets tired of spending money, and the people get tired of the constant change; they want to get back to a steady state too.”
The good news, he says, is that it means you still have opportunity to make big improvements long after you’ve grown comfortable with an automation system.
Quantifiable benefits include reduced staffing, less wasted product, increased quality and faster adjustment of controls at a level of higher precision and repeatability. With respect to safety, it removes distractions from operators, making routine events out of occurrences that would previously have set off an alarm flood.
Often discussed in the industry as state-based environments, the discipline of improving automation across a wider array of recurring events is the subject of a new ISA committee. While ISA-106, focused on sequential process control, is a few years away from releasing its first set of standards, Huffman says the goal is to “educate companies that processes run in states and, in order to keep them safe and profitable, it’s OK to take things out of operators’ hands and let the automation system do a lot more work.
“There are big companies that are embracing this because they are convinced it’s not only safer, but you can make money with it,” Huffman says.
Check back next week for the second of the five ways. And as always, we look forward to your comments.