Industrial Utility Efficiency    

System Assessment

“A single ¼-inch leak in a compressed air line can cost a facility from $2,500 to more than $8,000 per year. Locating and fixing leaks will result in significant savings depending on pressure requirements and energy costs.”

Compressor Controls

It was early summer, the air compressors were above the production floor on a mezzanine, and temperatures were heating up both outdoors and indoors. The compressed air system was comprised of three 500-horsepower centrifugal air compressors, and one 350-horsepower variable speed drive oil-free rotary screw air compressor.

Piping Storage

Compressed air represents one of the largest opportunities for immediate energy savings, which accounts for an average of 15% of an industrial facility’s electrical consumption. In fact, over a 10-year period, electricity can make up 76% of the total compressed air system costs. Monitoring compressed air usage, identifying compressed air waste and inefficiencies, and making investments in new compressed air equipment – including piping – are tangible ways businesses can cut their operating costs by lowering their electricity bill.

End Uses

Plant personnel had experienced ongoing problems with its process grinder performance due to unstable compressed air pressure. This created potential problems in terms of product quality. Grinders do not work properly without the proper pressure. Additionally, plant staff wanted to address these concerns, prior to a proposed 30% increase in production, and suggested raising the header pressure from the current operating pressure of 98 psig to 125 psig. The thought behind this was if the pressure from the header to the grinder process was dropping to 63 psig, then raising the pressure to the process would give the grinders enough pressure to work through higher peak production times.  

Pressure

A food processor was having compressed air problems, so they invited a compressed air auditor into their plant for an assessment and to help them size future permanent air compressors. The plant was experiencing low air pressure and detecting water in the compressed air lines despite having a desiccant air dryer. The auditor thoroughly analyzed the compressed air system production equipment and did end-use assessment and leakage detection. This article discusses the findings leading to a potential cost savings of 52% of the current level.

Air Treatment/N2

This plant has three production lines producing snack food. Depending on the time of year and production demand the plant can operate anywhere from no production lines to all three production lines. A thorough supply and demand-side system assessment was done at this plant. This article will focus on some recommended demand-side reduction projects including nitrogen generation, air vibrators, leaks and vacuum venturis.

Leaks

So you’ve purchased an ultrasonic leak detector after a sales person gave you a demonstration on detecting compressed air leaks. You’ve read all those articles on how air leaks are wasteful, expensive and leakage programs provide good paybacks. Perhaps you’ve even had a go at a leakage survey. Either way, by now you’ve realised leakage programs are not as simple as they sound and without an ongoing plan of attack, you will probably never see the results you thought you could achieve. This article is written to illuminate common mistakes made in leak surveys and hopes to provide guidance on how to turn that around.

Pneumatics

The advent of manifold-mounted, plug-in pneumatic valves has been a boon for machine builders. It allows them to mount complete valve packages in a safe and secure location on a machine. Using a D-sub connector, serial interface module, or similar single-point wiring system, all of the electrical control outputs can feed into one location on the manifold, greatly simplifying the wiring.

Vacuum Blowers

Every municipality and utility is facing the reality of rising energy costs. In 2010, the Town of Billerica, MA, which is located 22 miles northwest of Boston with a population of just under 40,000 residents, engaged Process Energy Services and Woodard & Curran to conduct an energy evaluation of the Town’s Wastewater Treatment Facility (WWTF) and pump station systems sponsored by National Grid. The objective of the evaluation was to provide an overview of each facility system to determine how electrical energy and natural gas were being used at the facility and to identify and develop potential costsaving projects.
With an eye toward strengthening its competitive edge, GKN opted for a new approach for the compressed air it uses to power metal molding machines in addition to a variety of other applications at its manufacturing facility. After careful analysis and planning with the Total Equipment Company located in Coraopolis, Pennsylvania, GKN opted to move beyond its aging compressed air system – and instead – outsource compressed air as a utility. Doing so allowed it to free up valuable floor space, while also achieving peace of mind since it can now count on a fixed cost for a reliable compressed air supply for years to come.
In terms of compressed air systems, it’s not unusual to see a plant with 10 to 15 air compressors, each of which is rated to provide 3,000 to 4,000 scfm of air. The air is used for everything from moving product, to powering pneumatic tools, pumps, and fans, to cleaning. There are easily 1,500 pneumatic control valves at a single plant.
Plant personnel had experienced ongoing problems with its process grinder performance due to unstable compressed air pressure. This created potential problems in terms of product quality. Grinders do not work properly without the proper pressure. Additionally, plant staff wanted to address these concerns, prior to a proposed 30% increase in production, and suggested raising the header pressure from the current operating pressure of 98 psig to 125 psig. The thought behind this was if the pressure from the header to the grinder process was dropping to 63 psig, then raising the pressure to the process would give the grinders enough pressure to work through higher peak production times.  
All industrial facilities use some form of compressed air, and in most, the air compressors consume a significant amount of the total energy bill. A facility with a good energy management system is likely to identify their compressed air system as a significant energy user (SEU). If the facility were using an energy management standard, such as ISO 50001, they would be required to assess and track the energy consumption of all their SEU’s. In the case of the metal processing facility, they were measuring the output of more than 250 devices within the plant, including building heaters, RTU’s, dust collectors, and also tracking the consumption of their electricity, natural gas and water. 
One observation I’ve made from 30 years of working with compressed air systems is to never underestimate the ingenuity of plant personnel when it comes to misapplying compressed air. We see something new in virtually every plant we visit, but one of the more common problems we encounter involves the use of expensive air for bearing cooling. 
By addressing inappropriate uses of compressed air and making changes to the compressed air production side of their compressed air system, a distiller of fine alcohol products reduced its energy consumption by 30%, saving $16,600 per year in energy costs - with more potential savings possible.
Experienced auditors become wary when they see desiccant dryers installed in customers’ plants. These dryers are required when a plant needs instrument-quality compressed air, or when compressed air piping is exposed to freezing temperatures. However, while desiccant dryers can gain this level of quality, the energy cost of stepping up from a dewpoint of 35 oF to a level of -40 oF increases quite considerably. To attempt to reduce the energy costs of drying to these low levels, heated blower desiccant styles may be used. This article describes three common desiccant dryer types, as well as some experiences, good and bad, with heated blower types.
This major food manufacturing plant in the Midwest uses compressed air and onsite nitrogen generation to operate multiple snack production and packaging lines. The plant spends an estimated $430,344 annually on energy to operate its compressed air system based on an average rate of 4.5 cents per kWh.
In most industrial plants, data is everywhere. It resides in flow through pipes, pressure in tanks, vibration on rotating equipment, temperatures in heat exchangers, and electrical energy power consumption in motors. If we can acquire this data and make sense out of the patterns we can take actions to make our plants more efficient and reliable.
On a recent project, at a polyethylene terephthalate (PET) blow-mold and filling operation, a very effective measurement plan resulted in a full synchronization of the supply side air to blow molds with significant reduction in total air use and increases in productivity and quality.