The name of the game for cogeneration plants, like AES Warrior Run in Maryland, is eliminating downtime. For Warrior Run, forced shutdowns, due to tube failures and lengthy inspections, were major contributors to costly plant downtimes. Mel Sines, Power Block Team Leader/Outage Manager, and Peter Bajc, Plant Manager, were eager to improve their longstanding process, so they brought in Gecko Robotics to perform robotic inspections in order to save their business millions and avoid extended, unplanned downtime.
To decrease downtime, Warrior Run always needed to improve preventative maintenance measures to ensure their assets would be reliable and in good health. Sines and Bajc have wanted to perform an inspection in the most time effective and thorough way. Furthermore, major issues of inspecting the evaporator tube bundles, located in the lower portion of the fluidized bed heat exchanger (FBHE), had always existed. "With a manual inspection, we're only able to inspect what we can reach," Sines explains, "and with our accessibility, it's extremely limited."
Traditionally, tube bundle inspections required manual inspectors to use handheld visual and ultrasonic testing (UT) tools to inspect areas that could be reached. With tube bundles over 12 feet in depth, and requiring airbags to push tube assemblies apart to inspect, very little was accessible, leaving a large portion of the bundles un-inspected. This problem was highlighted after a tube leak in the FBHE in 2016, which led to a lengthy forced shutdown. Sines had two options: replace all the existing tube bundles, or seek out an inspection company that could inspect at least 90% of the FBHE. After calling past manual inspection companies and coming up short, Sines reached out to Gecko Robotics.
In the spring of 2017, using a robot named EVA, Gecko Robotics performed thickness inspections of the critical FBHE at Warrior Run. EVA utilizes laser profilometry and visual inspection cameras to perform up to 100% tube coverage in assemblies like the FBHE. Gecko inspected over 22,000 linear feet across 1,400 tubes, collecting erosion data up to 180 degrees around each tube. To ensure data integrity, Gecko verified data acquired from the Warrior Run inspection by comparing with traditional handheld UT meters, proving the laser profilometry to be extremely accurate to UT. Gecko gathered over 125,000 data points, completing the inspection in just 4 days.
The final deliverable was carefully organized and visually presented on Gecko's online portal in the form of a heat map, allowing Sines and Bajc to decipher what areas were in need of immediate repair; "because of the inspection and good decisions, we were able to gain confidence from [Gecko Robotics'] data on our evaporator tubes," explained Bajc.
In addition to the FBHE inspection, Gecko was able to complete additional inspections for Warrior Run, including water walls and four silos without the need for scaffolding; collecting 1000x more data than ever before. The information collected was critical in helping Warrior Run prevent more potential equipment shutdowns.
"Because of the inspection and good decisions, we were able to gain confidence from [Gecko Robotics'] data on our evaporator tubes,"
- Peter Bajc, Plant Manager at AES Warrior Run
The following April, Gecko was back at Warrior Run performing even more inspections than the previous year using multiple robots, including EVA. From the erosion data collected, Sines and Bajc were able to make the decision, with full confidence, that the evaporator tube bundles could operate efficiently, and without failure for the next year, with plans of continued yearly inspections. This decision saved the plant millions and prevented a forced shutdown. The acquired data from Gecko's entire service offering, from UT, coating, and visual inspections, has ultimately allowed Warrior Run to plan for future maintenance repair and replacements during upcoming outages. "We rely on the deliverable and spread of [Gecko's] service," Bajc and Sines agree, "every 15 minutes means something to our business - speed is so valuable. Having less outage time and still getting the maximum amount of data is critical to Warrior Run."