The Maintenance Key to Improved Performance

Getting the Inside Scoop from a Control Engineer on How to Integrate O&M Knowledge and Relationships to Provide Long-Term Highly Successful Solutions

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Joe: The classic "E&I engineer" doesn't exist anymore at our plants. Neither does the E&I technician. The mechanics are more generalists in an effort to streamline maintenance. Corporate responsibility for much of the automation system design belongs to the process group. The basic instrument requirements for material handling have been pretty minimal in the past. However, strategies are becoming more interdependent. Safety instrumented systems are becoming part of the mix. E&I knowledge is becoming more critical. Process engineers don't always have the resources to interface all the components of these systems. Dependencies on the vendor and outside system integrators can leave you vulnerable to misunderstandings.

Stan: The corporate engineering department where I worked most of my career peaked at 1600 employees in the 1970s and declined to present day state of less than 16 employees. Recently when a large brewery was bought, the parent company decided to get rid of what was a first-class corporate engineering department. You recently went through a corporate buy out also. How did that go?

Joe: We had concerns that corporate engineering would be downsized. Our management made a convincing case that we had a special capability that gave us a competitive advantage. We are supporting more plants, and our corporate engineering has actually grown. There is value in a core group knowledge base. I believe we have seen the positive impact.

Stan: What are you doing to ensure continuity of expertise?

Joe: I am not thinking of retirement, but if I get hit by a bus, what happens? It is difficult to hire someone with 15+ years of experience to hit the ground running unless he or she has very specific knowledge. We have hired some younger engineers with 5+ years of experience with the intent to develop their knowledge base. The new engineers are often assigned to work on projects with more experienced engineers. The idea is to create a knowledge transfer environment. We also have a corporate mentor program. This offers the opportunity for cross-discipline knowledge transfer as well.

Greg: How useful are outside training programs?

Joe: ISA and vendor training can be too idealistic. They often only focus on the latest and greatest technology. This isn't always what you find when you look in the field. You need to get up close and personal to diagnose problems. Can you expect them to teach troubleshooting, especially for plants with processes, systems and requirements not discussed in the literature? It is always a control problem because it shows up in the control system. For example I recently witnessed a process variable that was oscillating so fast there is nothing the loop could do about it. I was asked to fix the loop. It was considered a loop problem that needed tuning. The real issue was some worn equipment that caused instability in the process. Once we got the equipment adjusted, the tuning was fine.

Stan: What are some of the difficulties in your applications and consequences of poor control?

Joe: Tons of material can quickly become a mess. We have a tricky process to start up due to dynamic formulations to get consistent moisture and protein levels. Solids material processes require a different mindset than your typical wet chemical plant. The process starts out as grain meal batching with some liquids added. The batch is heated with steam and water and then extruded through a die cap for multiple shapes and colors. Our customers are very discriminating. The extrusion process involves numerous quality parameters. The time scale for batching systems is often faster than what you see in many process industries. We may need to combine 25 ingredients or more into a 6-ton batch within five minutes or less. Some of these scales are very large. Isolation is difficult. Scale motion from vibration or wind can cause rapid weight swings. The operators see the source of this noise as the control system. We are producing much more with greater precision than the original intent of the equipment design. The control engineer really needs to understand the dynamics.

Greg: Have you used advanced process control (APC)?

Joe: Before we can apply APC, we need to improve turndown and repair. We have hundreds of extruder systems that were installed years ago. They have been modified and pushed to the limits. Preventative maintenance wasn't always consistent, and the consequences were not always obvious. We were susceptible to "You can keep running, right?" Maintaining plants that run 24/7 can be a challenge on the budget. Equipment wear may cause the need to push the process in a different way to achieve acceptable results. We are experimenting with ways to do predictive maintenance based on product run times. I have seen some wrong turns, such as the installation of an electrical actuator with a 90-second stroking time to save on air usage. This didn't work very well on a fast-acting flow loop. We started an initiative to do control system audits to fix instruments, tune loops and improve use of the systems in the control room. This has been very successful. We have seen significant increases in production rates as the result of these "tune ups."

Greg: What about optimization?

Joe: A large part of our job is dealing with existing equipment and process issues. New market demands can really put a stress on working within the limits of existing equipment. We are trying to optimize our processes for energy and moisture control. However, we have seen issues using APC systems as far as applicability and maintainability. The technology often requires a lot of oversight. It really needs a plant champion to keep it running properly.

Greg: We don't want to neglect the technician in humor, so here is my "Top Ten List" to finish up the first half of our interview with Joe.

October 2011 comic


Top Ten Things You Shouldn't Say When You Walk into a Maintenance Shop

(10) Hi! I am from corporate and I am here to help you.
(9) Good grief is that what you do?
(8) Why do you keep breaking stuff?
(7) According to my college course, valves and instruments respond instantaneously.
(6) According to my college course, loops have infinite turndown.
(5) According to my college course, all you need is model predictive control.
(4) I know what you are doing wrong.
(3) IT will show you how to use the new bus and network.
(2) IT will show you how to calibrate.
(1) IT will show you how to troubleshoot.

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