Industrial Utility Efficiency    

Piping/Storage

One of the most common problems in plants is low air pressure. One of the most common solutions is to purchase new air compressors. Often this advice leads to a poor return on investment with the company’s hard-earned money. Often the issues are related to demand, distribution, or both. Solving the wrong problem can be expensive from a capital and operating cost perspective. Determining root cause analysis may cost more up front, but will save tens if not hundreds of thousands of dollars long term.
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.
Many are familiar with the advances with improved technology in the compressed air supply. Such advancements as, proactive central air compressor controls to maintain optimum operation of multiple compressors to support ever changing air demands; improved drive systems such as VSD’s; magnetic bearing drives (centrifugals); and more efficient and reliable equipment taking advantage of modern manufacturing capability. These new technologies are very important in generating relative high energy cost savings, and are well promoted by the OEM equipment manufacturers.
Their job is to brake the cars by gripping the wheels. They are operated either pneumatically or hydraulically, with Alton & Southern Railway’s system using the former. Considering much of Alton & Southern Railway’s compressed air piping system dated back to its 1960’s installation date, there were leaks. As of 2012, it was determined one and a half compressors were running at 100% capacity just to maintain leaks. This equated to about 1,500 cfm at a cost of roughly $180,000 in electricity annually.
While late summer may not be the time of year many of us think about heat recovery, the potential for energy savings in compressed air systems should be on our minds year-round. For those involved with the compressed air systems within International Wire Group’s facilities, energy savings is on their minds each day. This culture of continuous improvement has everyone on the lookout for savings wherever possible.
The company specializes in fabrication of precision assembled customized parts for OEM’s and system integrators. Since 1997 the company has steadily grown in size and capacity as the demand for its high quality fabrications has increased.  Through the years, many new CNC machines, laser cutters and powder coat painting operations have been added, but with all the expansion the facility has amazingly kept the plant compressed air consumption low. This has been achieved by following excellent “best practice” compressed air efficiency principles and by keeping watch on system waste.
Technology is available which enables a compressed air flow meter to measure not only the magnitude of the flow, but also the direction. Why is this important? In this article we will describe two case studies where bi-directional compressed air flow measurement plays a key role to come to the right conclusions. In the first case study, we will describe an electronics manufacturing plant, which has a large interconnected ring network with two air compressor rooms located in different buildings. The two air compressor rooms are about five hundred feet apart. In the second case study, the effect of compressed air flow measurement upstream of a local receiver tank is described.
In aerospace manufacturing, tiny details matter most. For instance, if proper torque is not applied to the screws and bolts fastening an aircraft fuselage, catastrophic failures can result. Compressed air is used to power the tools needed to apply that torque, making the compressed air system a critical part of the facility, though it largely stays behind the scene.
During an Energy Review at a relatively new health care garment factory, in the Southwest, we found all three of the 100 psig nominally rated rotary screw air compressors were operating at 115-120 psig continuously. We asked the Production Superintendent if this was normal or if something had recently changed. He explained that initially they operated two air compressors but had to begin running the 3rd unit in ‘trim’ mode after some converting machines were up-graded. Then, a new larger converting machine was recently installed and air pressure quickly became a production issue. Since capital funds were tight, the project engineering team determined the third air compressor had sufficient capacity.  
Insufficient focus at the design phase will kill a project. In one aerospace project, insufficient detail was paid to the physical size of the air compressor. The compressor didn’t fit in the allocated space—requiring the extension of the building, and costing tens of thousands of unbudgeted dollars. That had a significant, negative impact on the project return. 
A Canadian fiberglass plant has completed a lengthy compressed air improvement journey and achieved significant efficiency gains by applying “the systems approach.” Along the way, the company ran across many frustrating problems, the solutions to which were only determined after the entire system was monitored holistically using data loggers. The overall compressed air audit led to a reduction in energy usage of 48 percent, yielding savings worth $17,500 per year. The project also qualified for a large utility incentive of $32,000 with a calculated payback of 4.4 years.