April 24, 2014
Industry at Large
Parker Piston Accumulators for Critical Wind Turbine Applications
Hydro-pneumatic piston accumulators from Parker Hannifin Corporation, the global leader in motion and control technologies, provide long-term effectiveness in critical wind turbine applications through significantly lower maintenance and servicing costs. Piston, bladder, and diaphragm hydro-pneumatic accumulators are used in a variety of wind turbine applications, including use with a power unit and pitch cylinder to feather blade pitch that enables the turbine to continually extract maximum power during fluctuating wind speeds. In addition, during excessive wind conditions or power failures an accumulator acts as an auxiliary power storage device to quickly and safely rotate the blade to a null position. Both the high speed shaft brake and yaw brake systems also employ accumulators as a fail-safe source of auxiliary power.
“While all three types of accumulators are used in wind turbine applications,” says Mike Schubert, marketing manager. “Piston accumulators, because they have less frequent service intervals and maintenance requirements compared to bladder or diaphragm units, will provide a lower total cost of ownership, saving substantial operating costs over the life of the turbine. As a general rule of thumb maintenance and service requirements for piston accumulators are 1/4 of that for the other two types.”
Bladder and diaphragm accumulator operation depends on molded flexible rubber bladders or diaphragms. Should there be a failure, it is sudden and allows the stored nitrogen gas to enter the system. Because of their small seal piston accumulators fail gradually and allow plenty of time for scheduled maintenance. “What most designers don’t account for in bladder and diaphragm accumulators is the inherent loss of pre-charge that occurs over time due to gas permeation through the flexible rubber compounds,” according to Chuck Taylor, project engineer. “And if a low temperature compound is used because of the wind turbine site location, the tradeoff to its use is higher gas permeation rates through the compound at working temperature, hence more frequent service checks are required to ensure that the proper pre-charge is maintained.”
Parker’s piston accumulator capability includes 1.5- to 20-inch bore sizes with capacities up to 200 gallons. All are designed to fit specific wind turbine applications utilizing a total custom-based systems approach that includes application engineering and worldwide support. To learn more contact an applications engineer at the Parker Global Accumulator Division at (815) 636-4100. Also visit www.parker.com/accumulator.