County Line Stone, a crushed stone and aggregate supplier in western NY, contracted Digitronik Labs to perform an upgrade of the burner management system in one of their hot mix asphalt plants. The goals of the project were:
- Replace the existing PLC with a fail-safe Siemens S7-1500F for enhanced safety
- Add a secondary PID loop for simple and efficient control of warm starts, making the system easier to operate and saving fuel
- Update the interface with additional control and feedback to improve usability and maintainability
- Add the ability to control gas and air independently for tighter temperature control
- Replace an obsolete legacy control component with a modern component with available spares
- Maintain full control of the codebase for internal modifications and to avoid vendor lock-in
- Create a reusable design and codebase that can be used to upgrade two additional plants
- Achieve FM approval and NFPA 86 compliance
Working closely with plant manager Mike Buyers and his maintenance staff, Digitronik investigated the existing system and meticulously planned each step of the upgrade. The project needed to be complete in time for the plant to come online in early spring, when the warmer weather would allow County Line Stone’s customers to resume their work paving roads.
Buyers is clear about the importance of the upgrade timeline: “This plant is one of the biggest profit centers for our business; it’s a point of sale. If the plant doesn’t run, our customers go to our competitor and it’s lost business that we’ll never see again.”
As with any modernization project, always expect the unexpected. The facility’s open network topology had all plants sharing the same address space, causing communication issues that were initially difficult to track down. However, once the problem was identified, it was quickly remedied by senior controls engineer Chris Coon.
When all was said and done, Digitronik completed the upgrade in time for County Line Stone’s busy season. The full project scope included:
- Electrical upgrades and legacy component replacement
- Build and install of a new remote I/O panel
- Improvements to the existing PLC program
- Reimplementation and enhancement of the HMI
- Commissioning of the new fail-safe PLC
- PID loop tuning
According to Buyers, this project had been on his wish list for quite some time. “I’ve wanted to do [this upgrade] here for over 10 years. It was just the magnitude of the project, knowing how long it was going to be down and then finding the right people to do it.” Added Buyers, “When it came to crunch time, you guys were all over it.”
One year later, work on the second plant has begun and is scheduled to finish in mid-April. Here’s looking forward to construction weather!