The most expensive component in the total cost of compressed air is energy. In fact, over the lifespan of a typical compressor, energy typically costs several times more than the purchase price of the compressor. The bottom line: maximizing energy efficiency saves you money.
The first step to reducing compressed air energy costs is to measure and monitor your compressed air system’s energy consumption, flow rates, and operating air pressure. Small adjustments can reduce your operating pressure and energy costs while improving flow rates and output.
For example, if your existing compressor is running at less than 65% of capacity, a smaller one could pay for itself in 18 to 24 months on average. If your compressor is more than 10 years old, cost savings with today's compressor technology could result in a payback in 18 to 24 months. A compressor that is both smaller and uses today's technology could pay for itself even faster.
An effective way to analyze your compressed air system is to draw a pressure profile. This profile will show the pressure drops through a system. These pressure measurements give feedback for control adjustments, determine pressure drops across components, and help to determine system operating pressures.
Here are 10 steps you can take to optimize your compressed air system and save energy costs.
- Turn it off.
There are 168 hours in a week, but most compressed air systems only run at or near full capacity between 60 and 100 hours. Depending on your shift pattern, turning your compressors off during the evenings and weekends could reduce your energy bills up to 20%.
- Fix existing leaks.
A quarter-inch air leak at 100 psi will cost you more than $2,500 a year. Pipe systems older than five years can have leaks of up to 25%. Because it takes energy to generate compressed air, any air that leaks is money wasted. Approximately 80% of air leaks are not audible, so to minimize these problems, third-party help in detecting the leaks may be a necessity.
- Prevent new leaks.
As Benjamin Franklin said, “An ounce of prevention is worth a pound of cure.” So, be proactive and look inside your piping system. A clean, dry pipe indicates good quality air and no corrosion issues. Dust in the pipe is caused by particles in the compressed air. If compressed air is not filtered, or if the filter is clogged, pressure drops will occur and the risk of end product contamination will increase. Sludge in the pipe is bad news and must be fixed immediately. Dust and sludge in a compressed air piping system will cause corrosion very quickly and will greatly increase the number of leaks. Dried and filtered compressed air keeps piping clean.
- Reduce pressure. Run at required pressures, not beyond.
Each 2 psig reduction cuts energy consumption 1%. Check the system pressure and resist the urge to turn up the pressure to compensate for leaks or drops in pressure due to piping problems or clogged filters. A central supply side controller can greatly reduce the operational pressure band and orchestrate air production much more efficiently and effectively.
- Check drains. Are your condensate drains stuck open?
Condensate drains on timers should be adjusted periodically to ensure they open as intended or aren't stuck open. Better yet, replace timer drains with zero-loss drains to stop wasting compressed air.
- Review piping infrastructure. Many systems aren't optimized.
A piping system design should optimize transfer of compressed air at the desired flow and pressure to the point of use. Increasing the size of a pipe from 2 to 3 in. can reduce pressure drop up to 50%. Shortening the distance air has to travel can further reduce pressure drops by about 20 to 40%. The more flow pushed through a pipe the greater the pressure drop will be. Pressure drop in a pipe increases with the square of the increase in flow. For example, if you triple the flow, the pressure drop will increase nine times. Air distribution piping should be large enough in diameter to minimize pressure drop.
- Change filters systematically -- not every once in a while.
Inspect and replace filters systematically to ensure the quality of your air and prevent pressure drops. Go beyond the air compressor and compressor room; there are several airline and point-of-use filters within the facility. Those are just as important to maintain as the air compressor and air compressor room filters.
- Recover heat. Compressing air generates heat – reuse it!
It’s simple physics that compressing air gives off heat, and as much as 90% of that heat can be recovered for use in your operation. For example, you can produce hot water for washrooms or direct warm air into a workspace, warehouse, loading dock, or entryway. The savings can really add up.
- Emphasize proper maintenance. Ignoring maintenance costs more.
As with most industrial machinery, a compressor runs more efficiently when properly maintained. Proper compressor maintenance cuts energy costs around 1% and helps prevent breakdowns that result in downtime and lost production. Protect your reputation and profits with proper maintenance.
- Identify and eliminate inappropriate uses of compressed air.
Inappropriate uses of compressed air include any application that can be done more effectively or more efficiently by a method other than compressed air. For example, high pressure air often is used for cooling or applications where much lower air pressure is required.
For a free copy of Atlas Copco's 156-page Compressed Air Best Practices Guide, email paul.humphreys@us.atlascopco.com. Put "Manual" in the subject line and provide your delivery address in the body of the email.