Industrial Utility Efficiency    

Technology

It is becoming a “best practice” to install a variable frequency drive (VFD) air compressor whenever one is replacing an old air compressor.  As a result, real systems have fixed-speed and VFD air compressors, mixed.  I have observed several VFD compressor sizing methods.  In my last article, I referred to a common method: size one VFD compressor for the whole system.  This can work.  However, if it doesn’t meet a higher peak demand, one or more of the old compressors will be started, and a mixed system results.   Another method is to replace a compressor with the same size, but with a VFD.  If the compressor that was replaced is large, a big VFD is installed.  If small, a small one.

Air Compressors

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.

Air Treatment

Compressed air is dried to prevent condensation and corrosion which can disrupt manufacturing processes and contaminate products. Water is the primary promotor of chemical reactions and physical erosion in compressed air systems. A myriad of desiccant dryer designs have been devised to provide “commercially dry” air, air having a dew point of -40°F or less, to prevent corrosion.  Desiccant dryers use solid adsorbents in granule form to reduce the moisture content of compressed air.

Blowers

High speed bearing technology is applicable for aeration blowers operating at much higher speeds than the typical 60Hz, 3600RPM for cast multistage units. High Speed Turbo (HST) units are usually single stage (though some utilize multiple cores) and rotate from 15,000 to 50,000RPM. At such high speeds, standard roller bearings cannot offer the industry standard L10 bearing life. Two types of bearing technologies have come to dominate the wastewater treatment market for these types of machines: airfoil and magnetically levitated. Often the two technologies are compared as equals, however, in many significant ways they are not.

Compressor Controls

Load-sharing is an important part of a multiple centrifugal-compressor master control system. It minimizes blow-off based on the available turn-down. In addition, remote start-stop saves more energy if load floats between different ranges. Finally, adding a screw compressor and implementing a hybrid control system might save the most energy and provide the best back-up. In any case, a well-instrumented system allows engineers and operators to assess, optimize and tune the system.

Instrumentation

Compressed Air Best Practices® Magazine interviewed Mr. Warwick Rampley, the National Sales Manager for Sydney (Australia) based, Basil V.R. Greatrex Pty Ltd. It’s not every day one is asked to deliver a system able to provide both a reliable compressed air dew point of -80°C (-112°F) and high purity nitrogen.  We work with some excellent technology suppliers and have engineered a rather interesting system.  Although our firm was founded in 1919, this application is one of the most demanding we’ve encountered. Basil V.R. Greatrex is a unique company as we focus only on compressed air measurement, compressed air quality and compressed air efficiency.

Pneumatics

The design of wastewater treatment plants is changing, and it has something to do with LEGO® bricks. More specifically, it has to do with how large and complex LEGO structures are built. If you follow the instructions carefully, you build module after module, eventually piecing them together to create a fully functional and cohesive unit.

Vacuum

It’s one thing to move materials during the production process, but when it’s a finished product on the packaging line, choosing the right material handling system is essential. Getting it wrong results in squandered production time when product loss occurs, and wasted raw materials.

Cooling Systems

As a result of compressed air awareness training and a focus on energy management, two facilities in different parts of the world have reduced their compressed air demand substantially by removing vortex style cabinet coolers from some of their electrical panels and reworking the cooling systems.  These facilities were previously unaware of the high cost of compressed air and how much could be saved if other methods of cooling were used. This article describes some of their efforts in demand reduction.
Made from various combinations of hops, grain, yeast and water, beer is a drink that has been produced for centuries. But while the ingredients are simple, the chemical processes behind the drink are anything but. Through various reactions, barley becomes fermentable sugars that are then digested by the active yeast to produce carbonation and alcohol. Although the basic principles behind brewing are little changed since their advent, the technological aspects are much improved. Today, large stainless steel tanks are used for fermentation and wort aeration, and complex, automated systems help with everything from temperature regulation to bottling.
Adsorption devices are commonly installed in compressed air systems to remove moisture.  Heatless compressed air dyers are the most common type furnished to meet the requirement for -40° F dew point “commercially dry” air, especially in systems of less than 1,000 standard cubic feet per minute (scfm).  Heatless air dryers are pressure swing adsorbers designed to retain the heat of adsorption within the desiccant beds during the drying process.
This article defines different aspects of regulator design and how they affect air wasted by droop. Some ways to reduce droop have be shown and some special case situations discussed. By taking care with regulator selection and installation, regulators can save large amounts of air instead of wasting it.  
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.
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.
The objective of this project is to help the building automation industry develop novel products that more cost-effectively identify faults (unwanted conditions) and inefficiencies in the operation of the compressed air plants of industrial facilities.  More cost-effective fault detection and diagnostics (FDD) products can come to the building automation marketplace only after that industry makes very significant advances in the state-of-the-art of its FDD software tools from what it currently offers.  Those advances require making common practice of rules-based artificial intelligence (AI) methods that the building automation industry has shown little to no familiarity with in its technology so far.  This project will utilize, under controlled conditions, the compressed air plant of the NIST campus as a facility for test and development of an embedded rules-based FDD tool based upon NIST expertise.
Rotary screw air compressor that makes its own lubricant from the surrounding air delivers oil-free compressed air to an environmental laboratory in Stuttgart, Germany - Many sensitive sectors of industry require oil-free compressed air. However, meeting this demand is often not as simple as it sounds. One way is to use oil-injected air compressors with downstream air treatment to meet the demand. A second option is oil-free air compressors, which operate without lubricants. Both versions have their own advantages as well as risks. Another alternative is to use rotary screw air compressors that use water as a lubricant.
When some people think about compressed air, they imagine the big, loud, dirty, unreliable machine in the back corner of their facility. Many businesses around the world rely on compressed air, and an unreliable air compressor can mean stopping an entire facility, costing thousands of dollars in lost productivity and repair labor. Additionally, that loud machine in the back corner is also a major energy consumer. So much so that many industry professionals refer to it as the “fourth utility.”
Figuring out the energy savings for the switch from pneumatic to electric tools requires an estimate of energy use for each case. The effect of replacing a few tools in a large compressed air system may be too small to detect using power monitoring on the air compressors. However, it is still a good practice, and when part of a larger program to reduce air consumption, the combined efforts will amount to something measureable. Another positive aspect may be that reduced compressed air use frees up needed air compressor capacity.
Compressed Air Best Practices® Magazine spoke with Mark Shedd, Head of Oil-free Air, Aggreko Rental Solutions - There are two distinct compressed air systems in a refinery or petrochemical environment: plant air and instrument air systems. Instrument air systems are almost always 100% oil-free air compressors on both the permanent and temporary systems. The demand for compressed air purity, in instrument air systems, is so high that the permanent install back-up system is usually nitrogen.