Reposition or Replace Feedwater Heaters in Less Than a Day
Air casters have proven efficient and safe in power plant heater moves
Air casters are being utilized in the power industry to ergonomically and safely move gigantic feedwater heaters and casks with a significant reduction in downtime. Feedwater heaters, the large, heavy tanks that house heat exchangers, are used to pre-heat water for boilers and to recapture water from steam driven turbines. These behemoth feedwater tanks are subject to the effects of corrosion and the stresses of continual heating and cooling on metal. They don’t last forever and getting them in or out for maintenance or replacement can take days. More and more power plants are using air casters to reposition or replace their feedwater heaters, reducing the net plant downtime to hours versus days.
On a recent feedwater tank move, the system engineer and his colleagues specified that air casters be used because of the plant’s structural configuration. Unlike rollers or wheeled equipment, air casters are omni-directional and take remarkably little manpower to move and maneuver—a capability of great value in tight spaces. AeroGo’s air caster equipment allows users to literally float heavy loads on a virtually frictionless film of air.
“We used the AeroGo air casters to drift the vessel into the mezzanine floor. We had columns, other pieces of equipment and valves in the way. It’s like threading through the eye of a needle. The new heat exchanger had to be set back in the exact place we pulled the other one out of. We had a 30-foot long vessel, six feet in diameter, and weighing 60,000 pounds. We needed to get it set within about a quarter inch of where the other one was set. Once we got it in there, the air casters made it easy to move the vessel around—you could bump it just a little bit.”
This power plant has used the AeroGo air caster system during three previous feedwater tank moves. The latest project had limited options due in part to factors inherent in the plant structure itself. “The issue is that the ceiling height between the floors may be only about 14 feet, whereas the height of the boilers and feedwater heaters themselves might be 12 feet. It’s just impossible to crane it out of there. If you slide it or roll it on rollers, you can run the risk of damaging the floor, tearing the plant up, or actually having one fall through the floor. AeroGo air casters solve the floor loading issue. The load is spread out over a huge area— it’s virtually the same load as you’d put on the floor by walking across it.”
The other advantage was the maneuverability that made placement “accurate to a quarter of an inch” possible. AeroGo equipment can easily traverse corners and make u-turns or spin a load around and back it out or in. “There are no limits on its maneuverability,” he said. “With wheels you’re limited in what you can do when snaking something out of a really tight area. It’s like trying to back a boat into a narrow garage. If you could just slide that boat side to side or rotate it and move it wherever it had to go, you easily fit it right in.”
Some staggeringly heavy loads can be moved by a single person. The team required to move one of the feedwater heaters consisted only of a crew of six and they probably didn’t even need that many.
The air caster system can completely eliminate or sharply reduce the need, potential liability and cost of other heavier equipment such as large cranes that require a certified operator. Stressing the importance of minimizing plant downtime, the system engineer noted that the AeroGo equipment did the job in only half a day instead of a day or more, plus avoided several times higher manpower costs that would have been incurred by employing other techniques. “We are regulated,” he noted, “But we’re still competitive. We still have to keep our costs down if we want to keep customers.”
Reinforcing another point that’s important in today’s liability and safety conscious industrial environment: “It’s a safer way to move it. With rollers, the heater could fall off. One tank we moved at another plant weighed 200,000 pounds. I’ve used air casters three times and, in my experience, none has ever failed. There are hundreds of these feedwater heaters in other plants across our system and they’re starting to pick up on this as well. It’s been established as the best practice across our company.”