Compressed Air Systems: Low Hanging Fruit for Energy Savings
Compressed air is a staple of many industrial facilities. These systems tend to be “leaky,” and finding and fixing these sometimes tiny holes and gaps is a great way to save money. “It is low-hanging fruit in that most people with a compressed air distribution network in their plant have some amount of leakage,” said Bill Barnes, the company’s Continuous Improvement Manager for Vac-Con, a Green Grove Springs, FL-based manufacturer of heavy duty, truck-mounted machines.
Barnes said that assessing and patching systems should be done systematically, either by the company or an outside expert. The first step – whoever does it – is to create a baseline to determine the amount of loss and, ultimately, the amount of improvement. This is done by measuring the output at the compressor and the output at various work stations. Losses can be isolated by comparing the measures at each place compressed air is used. A significant drop off between two stations indicates that a problem exists in between the two.
Organizations conducting informal inspections aimed at catching the bigger leaks can simply spray exposed parts of the system with soapy water. Carefully watching the plume of mist that is created will lead to most of the leaks, Barnes said.
That, of course, is for simple quick fixes. Companies with more extensive and complex systems — and bigger air losses — often bring in ultrasonic engineers. Barnes says that these organizations use equipment that can detect leaks by listening at levels beyond human hearing. Vac-Con, which uses compressed air for many purposes, has several facilities spread across 17 acres. It has an ultrasound firm inspect its systems annually.
Savings can be significant. Barnes provided information about electricity costs for Vac-Con’s welding building between April 2012 and 2013. A professionally conducted compressed air test and related remediation were completed at the end of October. Previous to the work, the monthly electric bills for the building straddled the $8,000 level. Afterwards, they dropped to around $6,000 per month.
In all, according to the company, the electricity bill dropped 26 percent. Welders use a lot of compressed air, so the results are dramatic. They point out, however, the value of paying attention to compressed air issues.
Bring in the experts can be expensive. Barnes said that it is best to be involved in the process: Walk through the system with the experts and embed a member of the team in the inspection to note the location of problems. In any case, make sure that the experts report the location and severity of leaks.
As with many other things, the amount of effort is key to the results. “The potential is there for zero leads [but] you almost have to accept a fractional amount of leakage unless you really put forth a lot of effort,” Barnes said. “Your level of success depends on the level of commitment to find what the issue is.”
Barnes offered two other tips for reducing cost from compressed air waste. The first is to cut down on the amount of compressors. Instead, store compressed air for when it is needed. “Storage is the ace in the hole,” Barnes said.
The second trick to reducing cost of compressed air is to more carefully customize the amount of air sent to a work station to the need. In many cases, Barnes said, there compressed air is over supplied to work stations. Matching compressed air distribution to the job at hand can be a big energy saver, he said.
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