Industrial Utility Efficiency    

Air Compressors

By far the most important development in the world of screw type air compressors has been the introduction of variable speed control using electronic variable frequency drives (VFD’s). Systems that run with at least one air compressor at part load can almost always operate more efficiently if a well-controlled VFD is added to the system. But what if a system has two or more VFD units? This article discusses the challenges in controlling multiple VFD air compressors with some suggested solutions.
This story begins in Coburg, Germany in the year 1919. Coburg was first mentioned in a monastic document dated 1056, but to speed forward almost nine centuries, Coburg would join the Upper Franconia Region of Bavaria in 1920 where it remains today. Back here in 1919, the United States passed the 19th Amendment allowing women the right to vote and Pancho Villa was attacking Juarez, Mexico. So it was in 1919 that in Coburg a gentleman named Carl Kaeser Senior would open a small workshop producing parts for the early automotive industry, along with gear wheels and special machines for the glass industry.
It was early summer, the air compressors were above the production floor on a mezzanine, and temperatures were heating up both outdoors and indoors. The compressed air system was comprised of three 500-horsepower centrifugal air compressors, and one 350-horsepower variable speed drive oil-free rotary screw air compressor.
The Best Practices EXPO & Conference held from October 13-16, 2019 in Nashville, Tennessee, saw a significant increase in attendance growing by 15% to 850 attendees from 20 countries. End user (factory personnel) attendance grew by 60%! The EXPO was also truly international showcasing 115 exhibitors from 16 countries and EXPO attendance was free for qualified industry personnel. This SHOW REPORT EXTRA complements our 2019 Best Practices EXPO & Conference Show Report.
The event brought together technology experts, systems assessment professionals, and manufacturing leaders – all of whom shared best practices and ideas manufacturing plants can use to save energy, improve sustainability initiatives and increase the overall reliability and quality of on-site utilities.
The 2019 AEE World Energy Conference and Expo was held September 25-27 at the Walter E. Washington Convention Center in Washington D.C. The event featured 14+ tracks, 56 sessions, over 260 individual speakers, and 62 exhibitors.  Both Chiller & Cooling Best Practices and Compressed Air Best Practices® Magazines were pleased to be in the literature bins at the 2019 AEE World!
Maintenance is the customer of controls and energy engineering is the customer of monitoring. And I discussed potential problems that can occur when combining monitoring and control in the same system. In this article, I will get more specific about building practical systems that address both controls and monitoring.
The members of the AICD (Association of Independent Compressor Distributors) send owners and senior management to the event. AICD member companies are independent companies selling and servicing air compressors in North America. “The AICD Board is pleased to announce we have added 18 member companies in the past year alone,” said AICD President Lisa Lewis (Michigan Air Solutions). “Vendor participation is at an all-time high as we’ve added 13 new exhibitors and special networking events for vendors to interact with AICD members.”
The team is building on engineering concepts that were used to develop the first hydraulic air compressor at Dominion Cotton Mills, Magog, Quebec, Canada, over 100 years ago. The basic principles of the HAC were then used to produce compressed air at 17 locations worldwide, including the last at Ragged Chutes near Cobalt, Ontario, Canada, over 100 years ago.  This article discusses the development the HAC in this decade and the continuing work at Laurentian University, Ontario, to modernize the concept.
The compressed air system at the mail sorting facility has been in service since the 90’s. Two older 50-horsepower (hp) air-cooled fixed-speed lubricated air compressors are housed in the equipment room of the facility. The air compressors duty cycle alternates between one another on a set schedule. A 240-gallon wet storage receiver is used to help with air compressor control, with the air flowing through the receiver to a non-cycling refrigerated air dryer and system filters before finally being passed to the plant.
Often, multiple centrifugal air compressors are set up to simply react to air demand, which requires the system to not only meet the new demand, but also make up for air depleted in the main header. This typically results in too much supply, which results in bypassing the air to atmosphere. The result is wasted energy use.