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.
Compressed air audits are valuable exercises on significant energy users in a plant.  Often done on main compressed air systems, these studies are also valuable on secondary systems, like dedicated low pressure circuits that feed production machinery.  An audit of such a system turned up some surprising results on a process that was initially thought to be very efficient.
It is common to see energy assessment specialists treat centrifugal compressors like positive displacement compressors when attempting to reduce compressed air system energy consumption. Unfortunately, centrifugal compressors are normally much larger, and miscalculations can easily represent hundreds of thousands of dollars in overestimated energy savings. These errors are not malicious; they result from oversimplified best practices perpetuated by individuals with limited centrifugal compressor knowledge. This type of knowledge is not readily available and most energy assessment specialists do not have access to engineering teams responsible for the technical development and design of centrifugal compressors.
Energy conservation measures (ECMs) associated with compressed air have received a significant amount of attention over the years, mostly due to a reasonably short financial return compared with other energy-consuming equipment. Over time, many of the recommended corrective actions to reduce compressed air energy consumption were simplified so much that they did not lead to positive results. One of the most common compressed air ECMs is reducing system pressure, and it leverages the best practice calculation —.5 percent power per psi — outlined in the Department of Energy’s Compressed Air Challenge. This article highlights more common issues associated with estimating energy conservation resulting from changing system pressure.
A couple of key principles must be considered if we want to understand and control the operating costs of your compressed air system. First, compressors pump air, they do not make pressure. The system creates the back pressure which the compressors must pump against. When the compressor delivers more air than the demand requires, the pressure rises and of course, the reverse is also true. Secondly, any component or application which forces the pressure to be higher than necessary creates wasted energy in the system. This waste is not linear to the increase in pressure but can be exponential for many reasons. However, the main contributors are artificial demand and the size of the compressors in the system.
International Wire Group, Inc. (IWG) headquartered in Camden, NY is the largest bare copper wire and copper wire products manufacturer in the United States with expanding operations in Europe. Products include a broad line of copper wire configurations and gauges with a variety of electrical and conductive characteristics , which are utilized by a wide variety of customers primarily in the industrial and energy, electronics, data communications, aerospace and defense, medical electronics and devices, automotive, and consumer and appliance industries.
As in most industrial categories, compressed air is critical to the operations of a plastics plant whether it is blow molding, injection molding, or other processes. The opportunities to improve supply side (compressor room) efficiency are similar to all industrial compressed air systems, but are even more prevalent in some plastics facilities, especially blow molding.
Pneumatic air cylinders play a major role in allowing a modern sawmill to produce at the high-speed production rates required. Stable air pressure is critical to allow the air cylinders to respond in a timely manner and avoid any production delays.
This automotive assembly facility has tremendous peaks and valleys in compressed air demand. Our audit using flow meters and pressure transducers with calibrated gauges has proven this. Our Phase 1 audit recommends the use of storage tanks and flow meters to reduce air consumption while stabilizing pressure.
“Instead of adding supply equipment, we fix air leaks and incorporate high-efficiency air nozzles, blower packages and point-of-use receivers.” These demand-side actions stabilize compressed air system pressure and this ultimately increases production output, reduces production down-time and spoilage costs, and decreases the power costs of the compressed air system.
Much attention and expense is often directed towards optimizing compressor control, clean-up equipment, system pressure / flow control and main system piping in an attempt to maintain adequate and stable pressure at the end use. Often forgotten are the components of the distribution system between the main system header and the end use.