By Ron Marshall for the Compressed Air Challenge
A plastic film manufacturer chose to purchase a very efficient VSD-style lubricant-free compressor and heat of compression dryer for a new plant expansion. The unit was designed to supply partial loads very efficiently by turning down the speed of the air end, with a proportional reduction in power consumption. The heat of compression created by the unit, rather than being wasted, is used to regenerate the desiccant in their air dryer, providing dew points well below 32° F. The remainder of the heat is sent to the plant in winter to help displace natural gas heating costs.
This unit was part of an energy incentive from the local power utility. As such, when the new compressor was commissioned, a compressed air auditor placed power meters and a flow meter on the unit to measure the performance. The meters showed that the energy efficiency of the unit was far less than expected. While the unit consumed full power, the compressed appeared to be putting out much less than rated flow. To rule out a flow meter error, flow tests were scheduled.
Before the flow tests were conducted, the compressor motor unexpectedly failed. As the compressor was still on warranty, the company sought a replacement at no charge. Unfortunately, a post mortem of the motor revealed a bearing problem caused by inadequate maintenance. The maintenance department had failed to lubricate the bearing at specified intervals, so no warranty replacement was forthcoming.
While replacing the motor and poking around inside the compressor, the manufacturer’s service technician found a large internal leak that was consuming a significant portion of the compressor’s capacity. The compressor’s sound proof shrouding had hidden this major compressed air loss.
The motor and the internal leak were repaired and the compressor efficiency returned to rated levels, saving significant electrical costs. Sometimes good things come out of bad experiences.
Learn more about saving money with VSD compressor control and recovery of heat of compression in our next Compressed Air Challenge seminar in your area. Visit www.compressedairchallenge.org for more information.
Filed Under: Pneumatic Tips