Industrial Utility Efficiency
Most industrial systems like compressed air have essentially random demand if you look at the long-term life cycle of the system. Hundreds, even thousands of independent small and large subsystems require constant or varying flow. These demands are typically not timed or synchronized with each other, so they aggregate to a fairly random flow profile, within a range. That range changes significantly when production processes change. Certainly a 2-week audit might show some patterns that appear predictable for demand A (“production”) and demand B (“non-production”) or day type, but they change over time as the plant adapts to new production systems and removes old ones. If demand was that profile forever, a lesser experienced auditor might be tempted to size one set of compressors that work perfectly for that profile but not for alternates.
When Compressed Air Consultants was starting, in 2003, we were approached by a company experiencing significant problems with their compressed air system. They had compressed air pressure problems causing production interruptions. They had moisture issues causing all kinds of havoc throughout the facility and appeared to be using far too many air compressors for what they wanted to accomplish.
Pressure regulators are everywhere compressed air is used. These simple devices, essential for safe and steady equipment operation, can be a big waster of compressed air. This article shows how with proper regulator selection, installation and setting management you can save compressed air and lower system pressures. This article looks at regulators on production equipment not central regulators or Process Flow Controllers.
A large fabric mill has implemented an energy management system based on the ISO 50001 standard to track their compressed air system efficiency. As a result of information gained from this system, and measures learned in some recent compressed air training, the company has reduced their compressed air system costs while at the same time achieving increased fabric production output. The savings were gained by not only optimizing the supply side of the system, but by also addressing the end uses.
A Canadian chemical plant installed a large heated blower-purge style compressed air dryer, years ago, to condition the instrument air system against freezing temperatures. The dryer selected was oversized for the connected air compressors and had unused on-board energy savings features. A compressed air assessment revealed the site air compressors and compressed air dryers were running inefficiently and causing in-plant pressure problems. Repairs to a compressed air dryer and the replacement of aging air compressors and dryers has reduced compressed air energy costs by 31 percent.
Technological trends in plastics manufacturing are driving the costs of production down. In industrial PET blow molding specifically, two innovative techniques have had major impacts over the last 15 years: “light weighting” the plastic bottles, and recirculating high-pressure compressed air. Both have helped to improve the energy efficiency of PET blow molding by reducing compressed air requirements dramatically.
PET Power Containers, a Canadian manufacturer of PET plastic containers, had plans for expanding its operations with the addition of more blow-molding equipment. Before the expansion could happen, however, the company needed to assess its compressed air system. Based in Vaughan, Ontario, PET Power provides a dizzying array of differently shaped and sized plastic bottles. Their operations run 24/7, and compressed air plays a key role in their primary manufacturing applications, including PET blow molding, PET preforming, and labeling bottles.
As a reader of this journal, you are well aware that large compressed air systems often have significant wasted air — often from leaks — that represent tens of thousands of dollars of waste per year. However, it is our experience that the so-called “low-cost” measures identified often go un-repaired, while other more costly capital projects get funded. Why? With an ROI of a half year or less, they seem like IQ tests to many compressed air auditors.
After more than 25 years in the compressed air industry, it still amazes me that many plant personnel and even those who sell compressed air products for a living don’t fully understand the relationship between flow, or volume (cfm), and pressure (psig). Walk into many body shops or small manufacturing plants, and you will find the compressor operating at an elevated pressure to satisfy the “demand.” If a plant has low air pressure on the production floor, what is the first thing that the maintenance professional does? You guessed it: He or she “jacks” up the pressure on the compressor, not realizing that he or she made the problem worse.
Compressed Air Performance Specialists (CAPS Inc.) is a compressed air consultancy located in Calgary, Alberta. In its most recent compressed air project, the company reduced a 200-hp, multi-compressor system down to a single, 100-hp variable speed drive (VSD) air compressor utilizing 75 hp of compressor energy (kWh), resulting in \$70,000 in annual energy savings.
Replacing air compressors, dryers and filters with more efficient models has saved electrical costs and improved compressed air reliability at the Canada Bread plant in Winnipeg, Manitoba. In addition to this, plant personnel found some additional savings by reducing air leakage and eliminating inappropriate uses. As a result, the plant reduced its compressed air electrical costs by 58 percent and qualified for a utility incentive.
