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Compressed Air on Demand PUBLIC ACCESS

Instead of Rebuilding Aging Equipment, a Manufacturer of Gear Motors Retrofitted its System to Provide a more Reliable Supply of Air-and Cut its Energy Bills by over $40,000 a year.

[+] Author Notes

Associate Editor

Mechanical Engineering 120(08), 74-75 (Aug 01, 1998) (1 page) doi:10.1115/1.1998-AUG-7

This article analyzes that the demand of compressed gas has increased manifold in automobile engineering. A manufacturer of gear motors retrofitted its system to provide a more reliable supply of air, which help reduce its energy bills by over $40,000 a year. When Bodine Electric Co. built a fractional horsepower gear-motor plant in Chicago 35 years ago, management intentionally overbuilt the compressed-air system to serve projected expansion. As it turned out, Bodine’s motor production never came near to stretching its compressed-air system’s capacity, largely because the company replaced its spray-paint delivery system with a powder coating technology. To ensure that compressed-air capacity was more in line with demand, assistance was sought in early 1996 from Chicago-based Commonwealth Edison (ComEd) in purchasing a new compressed-air system. In addition to the annual savings in electricity, the new compressors provide Bodine with a more reliable supply of compressed air. The system is completely backed up, so that even if one air compressor goes completely out of service, production will continue.

When Bodine Electric Co. built a fractional horsepower gear-motor plant in Chicago 35 years ago, management intentionally overbuilt the compressed-air system to serve projected expansion. As it turned out, Bodine's motor production never came near to stretching its compressed-air system's capacity, largely because the company replaced its spray-paint delivery system with a powder coating technology.

"I originally considered rebuilding our compressors to suit our actual needs, but when I found out this would cost $40,000 to $60,000 per machine, I considered replacing them with new units," said Brad Wood, facilities project coordinator at Bodine.

When the plant was built, Bodine installed 250- and 400-horsepower Elliott compressors and a Gardener Denver100-horsepower compressor. Because the two Elliott units delivered l, 700 and 1,000 cubic feet per minute (cfm) of air, respectively, the third compressor was never used.

To ensure that compressed-air capacity was more in line with demand, Woods sought assistance in early 1996 from Chicago-based Commonwealth Edison (ComEd) in purchasing a new compressed-air system. ComEd account manager Steve Lesniak arranged for Bodine's compressed-air system and actual compressed- air needs to be analyzed through ComEd's Marketing Technical Services department. ComEd performed a preliminary system evaluation that included examining the compressors in use at Bodine, measuring their load, and comparing it to the actual compressed air demand. They then calculated both the energy consumption and energy costs of the compressed air system.

The ComEd findings were next evaluated by Hank Van Ormer, an expert consultant on compressed air usage ' and president of Air Power USA in Pinkerton, Ohio. In December, Van Ormer drilled and tapped compressor supply pipes to install sensors that monitored the Bodine plant's actual air usage around-the- clock for seven days. Their analysis showed a peak use of 600 cfm on the first shift, reduced to 450 cfm on the second shift, and down to 325 cfm by the third shift.

Armed with this information, Van Ormer and Jim Pumper of ComEd suggested that Bodine replace its three aging, oversized compressors with three new compressed- air units and a sequencer controller that enabled the motor manufacturer to use its process energy more efficiently. In addition, Pumper and Van Ormer specified the size and type of the air compressor Bodine needed, along with the appropriate installation and controls.

In addition to the annual savings in electricity, the new compressors provide a more reliable supply of compressed air.

Bodine Electric Co. cut its energy bills by replacing these overbuilt Elliott air compressors with appropriately sized Ingersoll-Rand units to provide the air power needed for motor production.

Grahic Jump LocationBodine Electric Co. cut its energy bills by replacing these overbuilt Elliott air compressors with appropriately sized Ingersoll-Rand units to provide the air power needed for motor production.

Intelligent Controllers

Bodine put out bids to four major industrial compressor manufacturers: Quincy, Gardener-Denver, Kaiser, and Ingersoll-Rand. "In addition to speaking with the sales representatives, we also visited other plants to observe their compressors in action. Based on what we learned, we chose Ingersoll-Rand," said Woods.

Removing the older compressors was a challenge in itself, recalled Woods. "There is no longer a driveway adjacent to the boiler room, as there was when the original compressors were installed, so we had to break these six to seven-ton machines apart in the boiler room arid have riggers bring them up the stairway," he added.

Bodine then installed three 75-horsepower SSR rotary-screw air compressors, made by Ingersoll-Rand's Air Compressor Group in Davidson, N.C. These units use a two-stage separator consisting of a baffle located in the separation sump tank that performs first-stage mechanical separation of air. The second-stage separator element is contained in the dry sump created above the baffle. This arrangement limits carryover (air from the first stage, which may contain contaminants) to less than two parts per million, keeping the discharge air cleaner.

The SSR compressors are equipped with an Intellisys microprocessor-based controller, which enables operators to set parameters and make adjustments by using a manual panel. The Intellisys also drives an electronic stepper motor inlet control, which automatically throttles the compressor to match pressure to load and constantly monitors 12 prime compressor operating parameters.

Ingersoll-Rand engineers designed the SSR compressors with 40 percent fewer fittings, pipes, and hoses to minimize the possibility of coolant leaks. They also make maintenance easier by equipping the compressor units with spin-on coolant filters, top discharge of package cooling air, and multiple, latched panels.

Ingersoll-Rand also supplied a sequencer controller that serves as the main control unit, constantly monitoring compressed air needs and turning the individual compressors on and off automatically. Typically, only one unit is used for the second and third shifts because less air is required. During the first shift, one air compressor is usually running, while a second compressor loads and unloads air without running at full lo ad. This system avoids downtime by keeping one compressor available for backup or preventive maintenance.

"The bottom line is that Bodine never needs all three compressors running at one ti.me, al although if the need arises due to expansion, the third compressor could be used and an additional fourth compressor could be easily installed," said Woods.

In addition to the annual savings in electricity, the new compressors provide Bodine with a more reliable supply of compressed air. The system is completely backed up, so that even if one air compressor goes completely out of service,' production will continue. "The entire cost of the installation was about $125,000, so with the annual saving of $40,000, it will pay for itself in three years," said Woods.

Ingersoll-Dresser engineers eliminated 40 percent of the fittings, pipes, and hoses of the SSR Rotary Screw compressor to reduce the possibility of coolant leaks, and ease maintenance with spin-on coolant filters.

Grahic Jump LocationIngersoll-Dresser engineers eliminated 40 percent of the fittings, pipes, and hoses of the SSR Rotary Screw compressor to reduce the possibility of coolant leaks, and ease maintenance with spin-on coolant filters.

Copyright © 1998 by ASME
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