At a Midwest window manufacturing plant, the cooling process for the plastic frame pieces, after leaving the extruder, was critical to process productivity and quality. Too much cooling air (or not enough cooling air) would generate scrap and rejected product. The plants’ 17 extruders and 55 separate blow-offs in these lines had similar cooling stations at the cooling boxes. They consisted of about three hoses at each exit frame angled down to the extruded piece moving past it. The compressed air flow was controlled by a manual control valve set by an operator. The operator used his experience to control the flow delivered and thereby control the product quality.
“Sandblasting” is one of the oldest and most used methods of metal treatment. Various abrasive materials may be loaded manually or by a vacuum system pulling the “grit” from a storage tank. A control valve then operates with the compressed air (bypassing the vacuum pump), being forced into the tank pressurizing the receiver. When the high pressure compressed air goes out the discharge line, it pulls the appropriate amount of grit with it to effectively impinge against the targeted metal surface.
This textile plant uses compressed air in their knitting, sewing, and dye house operations and needed a system designed for the significant fluctuations in demand. Compressed air demand profiles were placed into four segments; 1st shift peak demand and minimum demand, and 2nd shift peak demand and minimum demand.
Assessing payback on engineered air nozzle and blower upgrades There are a variety of means factories can use to remove or “blowoff” moisture from a package. Open tubes or drilled pipe are often viewed as simple low-cost methods. However, there are considerable drawbacks to these approaches, most notably – increased operating expense. While they may be convenient and inexpensive in the short term, these approaches often cost 5-7 times more to operate than preferred alternatives.
Compressed air users looking for energy reduction often identify their air compressors as a prime area for savings potential. But …what about end uses? There are a large number of obvious measures that can be implemented, such as leakage reduction, reducing open blowing and eliminating inappropriate uses..however, there are other more technical opportunities available that involve properly specifying or redesigning existing pneumatic circuitry in compressed air operated machines and processes.
Most systems are sized on the supply side at many times more volume and significantly higher pressure than is actually necessary to support the real demand plus a fudge factor generally created out of fear. I am sure that had the OEM defined what is not only minimally necessary in terms of mass flow at density (pressure and temperature), but also with the intent of the highest possible efficiency, we would approach things very differently.
Recently, The Kroger Company’s Indianapolis bakery identified the use of compressed air in a blow-off and conveyor gap transfer as a major source of energy loss and cost waste. According to the U.S. Department of Energy, “inappropriate use” of compressed air like blow-off produces high pressure atmosphere bleed leading to significant energy loss and unnecessary operational costs. Carrying a 10-15% efficiency return (according to the Department of Energy), compressed air applications can often be achieved more effectively, efficiently and less expensively with alternative solutions using a high flow rate and moderate pressure.
A comprehensive compressed air system analysis should include an examination of both air supply and usage and the interaction between the supply and demand. Auditors typically measure the output cfm of a compressed air system and the input kW, calculate energy consumption in kilowatt-hours, and determine the annual cost of operating the system. The auditor may also measure total air losses caused by leaks and locate those that are significant.
When it comes to conserving energy in compressed air nothing is sexier than a big, old, oil-free 300 horsepower variable speed drive air compressor coupled with a heat of compression dryer tied to an energy management system with all the trimmings. If you’re like me, it’s hard not to let out a manly grunt after reading that sentence.
With energy cost increasing at 7.5% per annum for the past few years, most facilities managers and maintenance professionals are looking for the best opportunities for excellent return on investment projects, which can drive their operating costs in the opposite direction. Compressed air is an area where significant improvements are readily available.
Perhaps your facility recently had a compressed air system survey, conducted by an air systems services company, that resulted in a couple of major recommendations, such as: • Install a new smaller compressor and new control systems on all of the units • Repair the many air leaks (identified as 30% of your system capacity)