Digital Ultrasonic Compressed Air Leak Detectors
Compressed Air Leak Detector: Digital Ultrasonic vs. Conventional
Tools to identify the acoustic signature of a compressed gas moving from the high pressure to the low pressure side of a leak. Advanced detectors can also quantify the magnitude of the leak.
Item ID: 448
Process Loads & Appliances--Industrial Processes
Compressed air systems at industrial plants often experience leak rates of 20% to 40%. “Best practices” leak rates should be maintained at 10% or lower, but maintaining low leak levels requires periodic identification of leak locations, placing a dollar value on losses, tagging and perhaps photographing the leak sources, and using a follow up method to ensure that identified leaks are repaired.
Leak problem areas include couplings, hoses, tubes, fittings, pipe joints, quick disconnects, FRLs (filter, regulator, and lubricator), condensate traps, valves, flanges, packings, thread sealants, and point-of-use devices. Leakage rates increase with system pressure.
Current generation ultrasonic acoustic leak detectors have the capability of detecting leaks, but advanced detectors can estimate the magnitude of the leak loss in standard cubic feet per minute (scfm). Energy management staff can combine leak information with the cost of producing compressed air to demonstrate to management the benefits of conducting periodic leak detection surveys. The advanced detectors are "tuned" for the frequency range for compressed air leaks. TVA conducted the original tests where sound pressure levels were correlated with leaks from holes of various diameters and with known leakage rates.
Compressors have a full-load “specific package power” of about 20 kW/100 scfm. Total loss is about 400 scfm for a plant with 100 leak sources with an average loss of 4 scfm per leak. If repair could reduce these losses by 75%, total loss reduction is 300 scfm with a decreased power of 60 kW. For a continuously operating plant, this amounts to over 500,000 kWh in saved energy annually ($40,000/year @$0.08/kWh). Significant additional energy savings are achieved when the leak reduction allows operators to shut off one of their operating air compressors.
Baseline Energy Use: 480000 kWh per year per industrial plant
Total compressed air loss is about 400 cfm for a plant with 100 leak sources with an average loss of 4 cfm per leak. Oil-lubricated rotary screw compressors have a full-load “specific package power” of about 20 kW/100 scfm. The energy used to supply the compressed air lost due to leakage in a continuously operating industrial plant is thus: 400 cfm x 20 kW/100 cfm x 6,000 hours/year = 7 kWh/year.
Manufacturer's Energy Savings Claims:
Currently no data available.
Best Estimate of Energy Savings:
"Typical" Savings: 75%
Low and High Energy Savings: 50% to 75%
Compressed air leakage is often in the range of 30% to 40% of the compressed air produced. A well-managed facility could control the leak rate to less than 10%. If repair could reduce the baseline plant losses by 75% (from 40% to 10% of compressed air produced), total loss reduction is 300 scfm with a decreased power of 60 kW. For an industrial plant that operates 6,000 hours per year, this amounts to about 360,000 kWh in saved energy annually. Significant additional energy savings are achieved when the leak reduction allows operators to shut off one of their operating air compressors.
Energy Use of Emerging Technology:
120,000 kWh per industrial plant per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
A compressed air system that has a leakage rate of 400 cfm (or 40% of compressed air supplied) has a total compressed air requirement of 1,000 cfm. A 200 hp oil-lubricated rotary screw compressor will meet this requirement (A 200 hp Sullair oil-lubricated rotary screw compressor can provide 980 cfm at 100-psig).
Multiple compressors are often specified for backup/redundancy purposes, so we will examine the population of industrial air compressors above 50 hp. The 1998 Xenergy "United States Industrial Electric Motor Systems Market Opportunities Assessment" indicates a population of 86,503 compressors in the U.S. rated from 51 hp to above 1,000 hp (See Appendix B, for SIC 20-39, Overall Manufacturing). The number of compressors in the 51 to 100 hp size range will be divided by 2 to give a population of 200 hp "equivalent compressors" (36,450/2 = 18,225) yielding a total population of 68,278 larger compressors or engine rooms nationally that can benefit from the use of leak detectors.
The Northwest contains 4% of the nation's population and it will be assumed that industrial air compressors are distributed according to population. Thus, we have about 4% x 68,278 = 2,731 compressors in the Northwest that could be associated with air distribution system leak rates of 400 cfm and above. For a conservatively low energy savings estimate, we assume a leak rate of 400 cfm is associated with each of these compressors (including the larger ones). We also don't know how many industries are currently using ultrasonic leak detectors to periodically find and repair leaks. This is offset by the fact that operators of smaller compressed air systems would also benefit from the use of leak detectors.
Regional Technical Potential:
0.98 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Currently no data available.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.