From time to time our customers ask for suggestions for optimizing their compressed air systems. We are specialists in compressed air treatment (i.e. dryers, filters, desiccants, drains, etc.) but our approach with customers has always been to look at the entire compressed air system.
Compressed air is commonly called the 4th Utility, and as we all know utilities can get very expensive if not properly monitored. The U.S. Department of Energy has shown that in a typical industrial facility 10% of the electricity consumed produces compressed air. In the chemical and process industries the electric power dedicated to compressed air production can be as high as 30%.
Proper equipment selection and operation is necessary for operating an efficient compressed air system. Over time, as production facilities expand, there’s a tendency to add compressors even when that’s not really necessary. A comment I have heard over the years is, “We have to run the entire plant at 115 PSIG minimum. So we added a new compressor to maintain that pressure throughout the plant.” When I hear this type of comment I suggest that the operator look at the manuals for their pneumatically operated equipment. What are the minimum pressure requirements for these devices? Many pneumatic devices operate well in the 85 psig to 100 psig range. If this is the case, the installation of a pressure regulator at the device location will reduce the consumption of compressed air and, in turn, curb the demand for adding compressor horsepower.
[Editor’s note: Van Air Systems’ main fabrication plant recently reduced compressed air demand spikes of up to 600 SCFM in part by eliminating an unregulated point of use. This contributed toward a project that eliminated 60 HP of installed compression.]
Compressed air leaks are another big target. You can save enormous amounts of energy just by fixing leaks. First fix the big, audible leaks. A ¼” leak can cost over $8000 per year in wasted electricity. This is based on a cost of $0.05 per Kwh and constant operation of a typical 100 psig compressed air system. Then buy an ultrasonic leak detector. It will cost anywhere from $500 to $2000, depending on the features, but the expense is usually well justified. This type of instrument will help you find small, inaudible leaks that typically hide in couplings, valve seals, and nozzles. Incorporate leak checking into the regular maintenance tasks.
When you look for leaks in your compressed air system remember to check all your condensate drains. A manual ball valve that is cracked open on a separator or receiver tank can cost you as much in wasted electricity as a ¼” leak. Replace all the manual ball valves with zero loss drains valves or level controlled programmable ball valves. https://www.vanairsystems.com/products_automatic.html
Another item that is often overlooked is pressure drop. Each 1 psi of pressure drop you eliminate is equivalent to 1% in energy savings. If you are running a 200 HP compressor in your facility 24/7/365, every psi of pressure drop eliminated will save you $650.00 per year in electric utility cost, based on $0.05/Kwh and running the compressor fully loaded 85% of the time. The biggest pressure drop culprits are improperly maintained coalescing and particulate filters. Van Air Systems includes a pressure differential indicator on most filters. These indicators tell you when it is time to change the elements. Remember that differential pressure indicators, like anything mechanical, can fail. This means you should still visually inspect the integrity your filters and elements every 3 months and replace the elements once per year at a minimum. A ruptured filter element will display minimal or zero pressure drop. That will save you the expense of pressure drop, but if the element is ruptured it is not protecting your downstream equipment from oil and dirt. https://www.vanairsystems.com/products_filter.html