Industrial Utility Efficiency    

Air Compressors

The 2018 AICD Annual Meeting and Exhibition was held May 20-22 at the Hyatt Hill Country Resort in San Antonio, Texas.  The membership of the Association of Independent Compressor Distributors came together under the theme of “Roundin’ up New Business.”  “AICD membership has doubled over the past three years,” said AICD President Phil Kruger (Harris Equipment). “After selling out exhibit space in 2018, we believe our direction focused on serving the needs equally, of both vendors and members at our conference, is working.”
In an ideal world, we would all have plenty of space, time and money to create the perfect compressed air system. In practice, we have to balance our ideals versus what we can actually accomplish. Compressed air systems take considerable forethought and planning to achieve a perfect install; however, we can use some key takeaways from this article even if we are ever faced a less than ideal installation. Remember to keep the compressors cool, minimize piping pressure drop and to allow sufficient room around the equipment for service.
This article is going to identify two air compressor control situations that will preclude translating air use reduction in the production area into lower input energy into the air compressor.
The plant produces both molded and blow molded plastic parts on a 5 day per week, three shift schedule. Production and maintenance sometimes occurs on weekends, occasionally requiring the air compressors to run on a 24 x 7 basis so the practice was to leave the compressed air system always pressurized. The system consisted of three modulating lubricated screw compressors one sized at 150 hp and the others 125 hp (3 units), each controlled with their local compressor controllers.
A spectacular vision is gradually becoming reality in Cadarache in the south of France. Modeled on the sun, the ITER (International Thermonuclear Experimental Reactor) fusion system uses nuclear fusion to generate energy in order to secure humanity’s supply of electricity. One of the biggest challenges is the high temperature inside the reactor. Technology by Sauer Compressors is a key factor in cooling the reactor. The manufacturer has supplied the world’s largest system for helium recovery.
Compressed Air Best Practices interviewed Timo Pulkki (CEO), Hannu Heinonen (President, Tamturbo Inc.) and Mike Batchelor (Director of Sales Americas) from Tamturbo. Since the 1960’s, the Tampere region in Finland has been a birthplace of several air compressor innovations – many of which involved Kimmo Laine, a co-founder of Tamturbo. Mr. Laine was a leader in R&D in the air compressor business for many years since the 1960s. This included bringing a high-speed turbo air compressor to market later at Tamturbo. Working together in the 1980’s in a division of Tamrock, called Tamrotor-where Hannu Heinonen also worked, Mr. Laine met a gentleman named Jaakko Säiläkivi.
The air we breathe and the air compressors ingest is a mixture of gases, aerosols, biological material, and particulates. It’s a real mess! Particulate, for instance, is very harmful to humans, because lungs are complex oxygen separators, not filters. They tend to load up with particulate, this is harmful over time. There isn’t a sufficient “pre-filter” to prevent all harmful particulate from entering the lungs. However, humans prefer water in the air, gas, aerosol, and to a certain level, liquid form. A de-humidifier would not typically be a healthy addition to our built environments.
There are many choices of compressor technology and types of controls that can be used for variable demands. Some examples are rotary screw compressors with inlet valve control: variable speed drives: load/unload control; or centrifugal compressors with variable inlet guide vanes. However, in many cases, the efficiency of the overall compression process can be reduced significantly during lower flow demands, leading to more power per unit of air flow being delivered. It is very important to evaluate different available options and see how a plant can run most efficiently.
Larger air compressors, typically over 500 hp, in refineries, pulp and paper plants, chemical and other processing plants often have high-speed, multi-stage air compressors called “centrifugal” air compressors. As seen from a total system perspective, they are not much different than screw air compressors. They compress air to plant pressure from atmospheric conditions, and deliver it to the dryer. These types of air compressors have no internal wearing parts, besides bearings and seals, and are very reliable and efficient, at their best efficiency point. 
Knowing when to overhaul a unit is important, and there are certain signs indicating a unit needs attention. Performing routine fluid checks, taking oil samples and routinely checking for bearing vibration can unveil indicators suggesting an upcoming failure. Oil contamination with metal fragments usually indicates parts are wearing. It’s also important to take notice of airend temperature increases. If internal air compressor temperatures go up, it’s a good indicator the cooler may be failing.