New technology offers energy savings to water, wastewater treatment industry

MagnaDrive Corporation is touting its new technology for controlling the speed of motor-driven systems which reduces energy consumption in water and wastewater treatment applications by up to 50%. That will come as welcome news to managers of the nation's 55,000 community water systems and the 16,000 publicly owned and 60,000 industrially owned wastewater treatment plants.

MagnaDrive's adjustable speed drive technology, the MagnaDrive coupling (seen here), uses the power of rare-earth magnets to precisely control the speed that a motor can drive a load. The benefits include lower energy use and reduced equipment and maintenance costs.

How the technology works
In a typical application, the coupling is installed between a motor and the load the motor is driving, generally a pump, fan or blower. The coupling consists of two independent components that have no physical contact. One component, a precision rotor assembly containing high-energy permanent magnets, is mounted on the load shaft. The second component, a copper conductor assembly, is connected to the motor shaft. Relative motion between the magnets and the copper creates a magnetic field that transmits torque through the air gap between the components. In effect, the magnetic "pull" between the magnets on the load side of the coupling and the copper on the motor side creates the coupling force.

Varying the width of the air gap changes the coupling force, so the amount of torque transmitted between the motor and load can be continuously adjusted. This allows precise and efficient speed control for optimum performance, including "soft" starts. The result is a much more efficient use of energy. Because there is no direct mechanical connection between the motor and load, the MagnaDrive Coupling also eliminates the costly wear-and-tear of vibration.

Case study: Real-life field results
The Unified Sewerage Agency's Rock Creek Advanced Wastewater Treatment Facility in Hillsboro, OR installed a MagnaDrive Coupling on one of two 60-horsepower (HP) motor-driven pump systems in its bio-solids treatment process. The plant used both systems, operating together, to pump digester bio-solids to four belt presses, where they were pressed and de-watered. Variable frequency drives (VFD)controlled the speed of the pumps. The systems suffered from excessive vibration and were in constant need of repair. To reduce the vibration, the systems used an inefficient bypass valve, which wasted energy.

Equipment gave the Rock Creek facility a ‘remarkable return on its investment'
Not only did the MagnaDrive Coupling eliminate the vibration but its efficiency allowed Rock Creek to downsize from a 60-HP motor to a 20-HP motor. Rock Creek also found it could then run all four belt presses off the single 20-HP motor and pump. This eliminated the need for a second pumping system and the associated equipment and space. The result was a nearly 28% drop in electricity consumption for this bio-solids treatment process. The absence of vibration also allowed the closing of the bypass valve, reducing energy consumption an additional 23%. Total energy savings equaled 51%.

"We were pleased when the MagnaDrive Coupling delivered process speed control and energy savings with a non-electronic device," said Nate Cullen, P.E., senior engineer/project manager at the Unified Sewerage Agency. "An added benefit to us was the elimination of vibration and associated high maintenance costs. We are considering MagnaDrive for new process control applications, and as a replacement for older variable frequency drives as they fail."

Based on the success of its first MagnaDrive Coupling installed in November 1999 at Rock Creek, the Unified Sewerage Agency has continued installing MagnaDrive Couplings at Rock Creek and its sister plant, Durham, in Tigard, Oregon. The Agency is about to take delivery of its seventh unit.

For more information, contact MagnaDrive Corporation at 1600 Fairview Ave. E., Suite 303; Seattle, WA 98102; Tel. 206-336-5710; fax 206-336-5727.

Edited by Tracy Fabre
Managing Editor, Water Online
Source: MagnaDrive Corp.