Prime Time for VFD Systems
Prime Time for VFD Systems
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Prime Time for VFD Systems
By: John Bagnall 1 minute read

Down time is required for any plant or facility to properly maintain components, including pumps. The right planning at the start of a project can significantly reduce the loss of production and profit.

The crux of efficient air travel is the ability of airlines to refuel aircraft efficiently and economically and keep aircraft moving. Airport operators have all but mastered fast refueling capabilities, providing fuel pumping systems that can offer as much as 16,000 gallons per minute, depending on an airport's size, and refuel planes in as little as 15 minutes.

Challenge

Efficiency comes at a cost for many airports that use the traditional constant speed hydrant pumping system. These systems are designed to provide fuel at the pressure and volume needed during peak times. The only way to reduce that pressure during off-peak times is to throttle it back by using control valves that cycle fuel back through to the storage tank while the motor continues to operate at top speed.

This wastes energy — and, in essence, money — by constantly running the motor at full speed. It also puts unnecessary wear and tear on equipment. Both of these directly affect maintenance costs and could lead to a premature need to replace a pumping system altogether. Additionally, the sudden pump start to the peak-time pressure rate in older systems can cause a power surge for the power utility company's system because the constant speed hydrant system does not have a gradual pump start option.

Solution

Variable frequency drives (VFDs) could eliminate virtually every negative aspect of traditional fuel pump systems. VFDs work by speeding up and slowing down the motor to control the fuel pressure rather than keeping the motor at a constant higher speed and throttling it back with control valves.

The motor and pump are direct-coupled, so that the speed of the motor equals the speed of the pump. As the demand for fuel rises and falls throughout the day, sensors tell the motor when to increase speed, and thereby pressure, and when to back off.

Because the motor isn't constantly running the pump at full throttle, energy consumption can be reduced to an eighth of the energy used for a constant speed system, and the pressure is customized based on need. There is less wear and tear on equipment, and the VFDs can start gradually, lessening the sudden shock the power utility would otherwise encounter during startup.

Why Now?

VFDs are the current standard for airport fuel pump systems and have been used in Europe for the past 20 years or more. Yet only a handful of airports in the United States have installed this cost-saving system.

Until recently, the cost of installing a VFD system could not be justified. A 20-year return on investment rate didn't make fiscal sense, especially if an already-in-place constant speed system functioned properly and had plenty of life left.

But the cost to install a VFD — or retrofit an existing system — has come down significantly to be comparable to the cost of installing a constant speed hydrant system. Additionally, systems that may have functioned properly and made sense 10 or 20 years ago are now likely to be in need of repairs or replacement, making this the prime time to explore how a VFD system might be the best solution for aircraft fueling needs.

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