Energy Efficient Motor Coupling

Results

Energy Consumption: The calculateddecrease in consumption amounted toa 26 percent reduction of nearly 135,000kWh per year.Alignment: The Hershey Company’s policy isto perform laser-alignments on all of itsrotating equipment, but the fact that themagnetic coupling can operate undergreater tolerances of alignment makeslaser-aligning a customer option. Thosewho forgo that option will realizeadditional savings.Power at Start-up: Higher reliability ofnew system.

Applications

Conveyors • Bulk Material Handling •Compressors • Fans • Blowers • Chippers •Shredders • Crushers • Mixers and Pumpsup to 5000 hp

Snapshot

Objective: The Hershey Company, NorthAmerica’s largest producer of qualitychocolate, is committed to reducing itselectrical demand by 2 percent annually,its electrical consumption by 3 percentannually and its carbon footprint by 10percent, with an emphasis on its plantfacilities having zero landfill impact.The company wanted to demonstratethe energy-savings potential of replacinga conventional motor-to-pump connectionwith a magnetic coupling that transmitstorque through an air gap.

Solution: The Hershey Company had acentrifugal-type, raw-water service pumpfitted with a magnetic coupling. Thephysical attributes of a magnetic couplingnot only saves energy but extends equipmentlife because it eliminates vibration. Thephysical separation the coupling createdbetween themotor and the pump also allowsfor visual inspections of the movement ofthe pump shaft, which could detect theneed for repair and prevent catastrophicfailure. As a result of this demonstrationproject, the company is able to captureenergy savings in an area where it waspreviously impossible with conventionalmotor couplings, and anticipates extendedequipment life. The Hershey Company hasstarted to identify other potential sites forthe new coupling and is evaluating similartechnology used for adjustable-speed drives.

Case Study The Hershey Company 2010

Background:

The Hershey Company (NYSE: HSY) is thelargest producer of quality chocolate inNorth America and a global leader inchocolate and sugar confectionery. It isheadquartered in Hershey, Pennsylvania,and has operations throughout the worldwith more than 12,000 employees andrevenues of more than $5 billion.

The company is engaged in energy andcarbon footprint reduction programs withgoals to:• Reduce electrical demand by 2 percentannually.

• Reduce electrical consumption by3 percent annually.

• Reduce its carbon footprint by 10 percent,with an emphasis on its plant facilitieshaving zero landfill impact.

The Hershey Company worked withPPL Electric Utilities and a couplingmanufacturer to demonstrate theenergy-savings potential of replacinga conventional motor-to-pump connectionwith a magnetic coupling that transmitstorque through an air gap.

Application:

This project retrofitted a 125-hp, 1780-rpm,raw-water service pump with a magneticcoupling. The magnetic coupling wasfirst installed and placed into operationon November 27, 2009. The pump is acentrifugal-type pump, manufactured byWorthington, which boosts water fromthe onsite well system to the raw-waterstorage tank. The pump starts and stopsautomatically as the tank level fluctuates.Its normal operation is 2 starts per hourafter which it runs for 15 minutescontinuously, changing to 3 starts per hourduring the summer months.

The coupling was installed by amanufacturer that provides magneticcouplings, mechanical soft-starts,torque-limiting couplings and adjustable-speed drives to a wide range ofindustries. Each of these productsoperates with rare-earth permanentmagnets and copper conductors, thephysics of which inherently save energy.Each also physically disconnects themotor from the load, thereby savingenergy and extending the life of the drivetrain. The relative motion between theconductor rotor and extremely powerfulpermanent magnets contained in themagnet rotor creates a magnetic field inthe conductor’s rotor, transmittingtorque across the space between the

components and, in this case, turningthe pump shaft. Again, this not onlysaves energy but extends equipment lifebecause the coupling eliminatesvibration transmission and can tolerateup to an eighth of an inch ofmisalignment between shafts.

The test used a commercially availablemagnetic coupling with no modificationsrequired to the drivetrain other than anew coupling guard.

After the coupling was first installed,vibration on the motor and the pumpdropped significantly.However, observationsof visual movement of the pump shaftindicated that the pump had a thrustbearingwithabnormalwear.This observationwas possible only due to the physicalseparation the new coupling createdbetween the motor and the pump.Otherwise, it might have gone unnoticeduntil a complete bearing failure in thepump occurred, causing potential plantdowntime.

Since the existing pump needed repair toprevent catastrophic failure, The HersheyCompany decided to install a new pumpand then compare data based on thebenchmark of a typical hard-coupledsystem versus the system with themagnetic coupling in place.

Conclusion:

The previous data proved this project tobe a success. The Hershey Company is ableto capture energy savings in an areawhere it was previously impossible withconventional motor couplings. In addition,the company expects the equipment life(motor, pump and downstream valves) tobe extended.

The previous pumping operation requiredthat a downstream valve be throttledsignificantly to operate the motor underits specifications, about 150 amps. Thisaction would keep the motor fromoverheating, but it shortened the valve’slife by exposing it to unnecessary stressesdue to the possibility of cavitation fromhigher-than-necessary velocities. The use

of a magnetic coupling means the valveneed not be throttled and can beused as intended, left in the “open”position, and for isolation only. Themagnetic drive’s inherent energy reductionnow allows the pump to run within themotor specifications.

Observed overall reduction in vibrationof the motor and pump amounted to 15percent. This vibration reduction, whiledifficult to quantify in terms of cost indowntime, man-hours and equipmentmaintenance, could result in thousandsof dollars of additional O&M savingsand a shorter overall simple payback.This project’s simple payback based onenergy savings alone for the coupling andthe installation is less than one year.

Next Steps:

As a result of this demonstration project,the Hershey Company has started toidentify other potential sites for thenew coupling. Decision-making and cost-justification is easy when the paybackperiod is calculated at less than a year.

The Hershey Company is evaluatingsimilar technology used for adjustable-speed drives.And by also taking advantageof PPL Electric Utilities’ E-power rebateand incentive programs for energy-efficientequipment, the company may achieveconsiderable savings financially whilemoving consistently toward meetingits energy and carbon footprintreduction goals.

Alternative Applications:

Industries that may typically use magnetic-coupling technology are mining, cement,HVAC, agriculture, manufacturing, waterand wastewater treatment. Commonapplications include conveyors, bulkmaterial handling, compressors, fans,blowers, chippers, shredders, crushers,mixers and pumps up to 5000 hp. Theseapplicationsmay provide solid opportunitiesto evaluate magnetic-drive couplings toreduce electricity use, wear and tear onequipment, and maintenance costs.

Information on PPL Electric Utilities’ E-power rebates andincentives is available at www.pplelectric.com/e-power.Rebates are retroactive for projects that were installedafter July 1, 2009.