Compressed Air System / Operational Excellence / Energy Management

5 tips for tackling compressed air optimization

Here's how to set yourself up for success with a compressed air optimization project.

By Neil Mehltretter, Kaeser Compressors

Chances are, your compressed air system is the lifeblood of your production line. And although compressed air is vital to production, compressed air optimization projects tend to be myopic, failing to take into account how each piece contributes to plant processes.

A successful optimization project, by contrast, will allow time for analysis of the current state of the entire system. It will rely on a holistic approach to help personnel understand how individual components work together and impact overall efficiency. It will take into account leakage, maintenance, pressure control and energy use and will result in creating a customized plan to move forward. In short, it will depend on looking before you leap.

A successful compressed air optimization project requires some careful planning and strategy. Here are five tips for approaching one.

Tip 1: Conduct a system assessment

Before you start on the path of optimization, you need a reliable road map to guide your actions. Beginning with a thorough system assessment will help prevent missteps later on. A system assessment (also sometimes referred to as a compressed air audit) will establish your plant's demand profile. A demand profile can help you understand how much compressed air you are using, how much extra capacity you have, and also how plant demand changes over different shifts and days of the week.

Many optimization projects begin with the assumption that more capacity is needed. This is sometimes true, but it’s quite often the case that purchasing additional equipment would be wasteful. However, this is something that can be confirmed only by taking careful measurements over a period of time and then analyzing the data. Here’s one example (Figure 1):

This chart shows an actual demand profile from a manufacturing plant. The plant wanted to purchase additional compressors to address downtime and pressure fluctuation problems. It conducted an assessment to help determine the size and number of compressors needed. The actual findings, however, revealed that the plant wasusing only half of its available capacity and that leaks accounted for 45% of plant demand. In this case, the plant saved a considerable amount of money on energy, maintenance, and capital costs by addressing system issues instead of buying more compressors.

As illustrated in this chart, an assessment can also identify nonproductive loads, such as leaks. Although it will not show the amount and location of each individual leak (this is something that can only be done with a leak detection audit), it can give an overview of the amount of air you are wasting to leaks. If you know that your plant has a high leak load, you may want to conduct a leak detection audit to identify the leaks and fix them prior to conducting the compressed air assessment, as this will give you a much more accurate demand profile. Further, fixing leaks provides immediate savings – something that can go a long way inpersuading upper management to proceed with additional energy-efficiency initiatives. A single quarter-inch leak for a system running at 110 psig, 8,760 hours a year, and $0.10/kWh costs $17,818 annually. And that’s just one leak. Think of how many you probably have in your system – the savings potential is huge.

Tip 2: Get buy-in

Having the best plan of action for your energy-efficiency improvements means absolutely nothing if you don't have the support from key decision-makers to implement the changes. Unless you control all of the resources necessary to source, select, purchase, and install new equipmentor make changes to existing equipment, you need to begin your optimization project by getting buy-in from those who do. Getting buy-in from the start will pave your optimization project with more than just good intentions.

This is how many projects get derailed before they begin. Plants may conduct an assessment or have a consultant make recommendations for improvements, but when it comes time to put those recommendations into practice, they never follow through. The report is emailed for review, lost in the black hole of inboxes, and ultimately forgotten (or ignored). If, however, you begin by getting everyone on board with the optimization project and you work together to set specific, realistic goals, your project will have a much better chance of success.

The compressed air assessment will provide you with cold, hard truths about your system and will explain the system in terms upper management understands: cold, hard cash. The assessment will provide energy saving recommendations and different options for obtaining different levels of savings. Use the language of dollar signs to communicate with management, and don’t forget to include cost savings for maintenance and downtime.

This is especially important if you are looking at replacing aging equipment and your production demands cannot tolerate downtime. Often, the cost of downtime for compressed air equipment can exceed the cost of a backup compressor. Plus, the extra savings resulting from  using your compressor as a heat source either for space heating or process water heating can far exceed any energy-efficiency savings potential.

Tip 3: Fix the leaks

We’ve already mentioned the cost of leaks, but it bears repeating: Failing to fix the leaks in your system is leaving money – potentially a lot of it – on the table. The U.S.Energy Department estimates that as much as half of all compressed air generated is wasted, with around 25% going to leaks. And that is a conservative estimate;we’ve seen plants with leak loads as high as 50%.

Because fixing leaks provides immediate savings and leaks are an ongoing concern for every compressed air system, consider adding a leak-detection program as part of your optimization project. A comprehensive leak-detection program willconsist of annual leak detection and a specific plan for tagging leaks and repairing them based on their size. Education is also key to a leak-detection program’s success. Empowering employees to be vigilant in monitoring piping, hoses, and quick-release fittings will pay dividends when it comes to leak detection. That single quarter-inch leak costing $17,818 annually, could be a ball valve cracked open on a receiver, rather than installing a no-loss air drain, which typically costs less than $1,000. That’s a great return on investment!

Tip 4: Think long-term

When it’s finally time to implement changes to your existing system based on the assessment results, it’s important to think longterm. Avoid the temptation to simply grab existing equipment from other plants or to use something that you can get for a deal at an auction. Think longterm and make sure you select the right equipment for the right reasons. This may mean more than taking any old compressor that can produce the required amount of flow to meet the demand stated in the assessment charts.

There are other factors to take into account. Consider, for example, the compressor’s communications capabilities. With the advances in technology and the emergence of the IIoT, now more than ever it’s important to understand how purchasing decisions today will impact the plant five and 10 years down the road. Take a look at how the compressor can communicate with the plant and with a system master controller. Without a system master controller, you won’t be able to achieve maximum efficiency as the compressors will run independently (causing multiple units to cycle unnecessarily) and typically operate the system at a higher pressure than required. In addition, system master controllers offer robust remote monitoring, energy monitoring, and predictive maintenance capabilities.Having equipment that easily connects to these controllers will save a lot of headaches as plants move toward the realization of the "smart factory" concept.

Secondly, part of thinking longterm is understanding the cause-and-effect relationship of your system's issues. Don’t focus only on the problem in front of you:There may be underlying issues in need of a fix. Once these are addressed, youcould end up saving a lot of money over a number of years.

Low pressure is a common compressed air problem, and many plants respond by increasing system operating pressure or adding compressors. If, however, the pressure at the point where the air leaves the last air treatment component or the storage receiver is greater than 5 psig above the real requirement of the point-of-use equipment, the actual problem is probably with the distribution system. The piping could be undersized; it could be leaking; or poor connection practices could be in place.

Keep in mind that every 2-psig increase in system pressure costs an extra 1% in compressor efficiency. Cranking up the system pressure may be a quick fix, but it will cost you a lot more in the long run than addressing the actual problem with the piping would.  

Tip 5: Confirm the changes are working

After you’ve implemented the changes based on the assessment findings, check to make sure they are as effective as anticipated. This can be done with a follow-up assessment. Depending on the system size, it's good practice to conduct an assessment annually given that demand can change over time.

Another option would be to utilize the equipment’s built-in energy monitoring capabilities. Some compressors can save performance data for later download and analysis. Better still, advanced system master controllers can record data for the entire system – pressure, flow, temperature, and energy – analyze it, and generate reports on demand. This is an invaluable tool for proactive energy management and also for compliance with ISO 50001 energy management standards.

Whatever route you take, be deliberate about confirming the changes' effectiveness and about monitoring system energy consumption on a regular basis.

This is an exciting time in manufacturing as plants move to improve processes and embrace new technology to improve their business. Using compressed air assessments as a tool to understand your system and to explain system performance to upper management can mean the difference between a fully realized optimized project and a dead end.