ENERGY CONSERVATION IN PNEUMATIC SYSTEMS Solutions That Save
Do we recognize the cost of air?
Should you focus on compressed air savings? Typical Plant Power Consumption (kW) Idle Mode
Discussion Topics 1. Plant Case Study – The Ripple Effect Every change, good or bad, results in other changes 2. General Overview of Energy Conservation 1. Air Quality 2. Air Leaks 3. Non-Productive Use of Air 4. Design Improvements 5. Idle Mode Demand 6. Over-Pressurization
Plant Case Study Here’s what can happen when complacency sets in
Plant Case Study At Start Up 65 psi 30 CFM 65 psi 30 CFM 65 psi 30 CFM 65 psi 30 CFM Total Case Packer Demand = 600 SCFM Additional Plant Usage = 200 SCFM 2 Compressors running 100 HP @ 90 psi
Plant Case Study Six Years Later 90 psi 80 CFM 100 psi 90 CFM 105 psi 100 CFM 109 psi 105 CFM Total Case Packer Demand = 1,875 SCFM Additional Plant Demand = 1,350 SCFM 9 Compressors running 100 HP @ 115 psi
What happened? The artificial over pressurization of CP #1 and CP #2 starves CP3 thru CP20. Other operators responded to the pressure loss by elevating their own pressure, which results in excessive flow on each machine. This leads to a plant wide pressure elevation which in turn elevates the flow on every unregulated user including leaks .
What was the catalyst for all this? Poor Air Quality due to lack of proper filtration Food grade oil was used in compressors: Oil easily migrated downstream (incorrect mainline filtration) Oil reacts poorly to heat - both in total life and in varnishing Direct-operated valves stick due to limited shifting force Internally piloted valves required higher pilot pressures Heat build up in valves contributed to failure (leaking & sticking). Poor filtration/valve selection for the environmental conditions. Plant addressed the symptom, not the problem .
Financial Ramifications Case Packers Costs – 1875 SCFM @ $0.056 / kWh Annual total $174,606 Additional Plant Demand – 1350 SCFM Annual total $125,716 Total annual cost to the plant $300,322 Initial annual cost to the plant $78,419 Additional cost to the plant $221,903 × × × 0 746 BHP . Hours of Operation Cost per kWh = Annual Cost Motor Efficiency × × × 200 0 746 8760 $ 0 . 057 . = = $ 78 , 419 Annual Cost 0 . 95
Additional Ramifications Lost production due to pressure swings Additional breakdown calls for compressed air issues Elevated compressor maintenance costs Water and oil carryover issues High scrap rate relative to other plants Increased capital budget Significant infrastructure upgrade required Cost of compressed air was ~4 times original value
How did we fix this? Address filtration issues in compressor room to minimize oil carryover Added backup filtration at point-of-use Used metal bowls which will not deteriorate from compressor oil Added service indicators Added tamper resistant regulators so that pressure would not be elevated Replaced direct-acting valves with indirect-acting valves Indirect-acting valves are less prone to sticking & generate less heat Fringe benefit: Indirect-acting valves lower power consumption from 9 watts to 1 watt Controlled pressure at point-of-use so that pressure could be restored to 90 PSI Took un-needed compressors offline, and rotated them into service periodically
Energy Conservation Overview Where do we go from here?
Energy Conservation Overview Energy efficiency is often overlooked on pneumatic systems. The pneumatic products applied have a far reaching effect on energy efficiency. OEM pneumatic product selection is often based on price. Very little consideration is given to energy consumption, compressed air quality, environmental conditions or sustainability. When evaluating your compressed air system for energy inefficiency, the first and least expensive place to start is with your pneumatic point-of-use systems.
Areas of Energy Conservation Areas of Focus 1. Air Quality 2. Air Leaks 3. Non-Productive Use of Air 4. Idle Mode Demand 5. Over-Pressurization
Air Quality
Air Quality Sustainability Considerations Dew point and Particulate Contamination levels are managed by: Mainline Filter Point of Use Filter Dryer
Leaks
Cost of Air Leaks & Potential Savings DISCHARGE THROUGH AN ORIFICE DIAMETER OF ORIFICE, INCHES 1/16 1/8 1/4 1/2 3/4 1 INCH PRESSURE DISCHARGE IN CUBIC FEET OF AIR PER MINUTE 4.79 19.2 76.7 307 690 1227 70 PSI Annual Cost To $590 $2,269 $9,062 $36,281 $81,545 $145,009 Operate 100 PSI 6.49 26 104 415 934 1661 Annual $765 $3,072 $12,290 $49,045 $110,382 $196,300 Cost To Operate 125 PSI 7.90 31.6 126 506 1138 2023 Annual Cost of $931 $3,734 $14,890 $59,800 $134,491 $239,082 Leak
Leaks 95% of leaks occur at a pneumatic product other than the mainline plumbing. The most commonly failed components are: Fittings and tubing Air prep units i.e. filter, regulator, lubricator (FRL) Cylinders or actuators
Why are they leaking? Fittings and Tubing Fittings and Tubing 1. Faulty installation – Accounting for 70% of failures tested during our audits. 2. Poor quality – Tubing or fitting failure not caused by installation or the environment. 3. Misapplication – Fittings or tubing exposed to wash down or other environments they were not manufactured to handle.
Why are they leaking? Air Prep Units Air Prep Units (FRL’s) 1. Age and general wear – Most leaking components showed failures indicative of general wear which accounted for approximately 45% of failures. 2. Internal exposure to water, Polyolester and Diester oils or rust – These leaks tend to be the largest, accounting for approximately 45% of failures. 3. External damage, operator or mechanical force – Accounting for 10% of failures.
Why are they leaking? Cylinders Cylinders 1. Internal exposure to water, Polyolester and Diester oils or rust – Accounting for approximately 55% of failures. 2. Age and general wear – Most leaking components showed failures indicative of general wear which accounted for approximately 25% of failures. 3. Misapplication – Accounting for approximately 20% of failures.
Leaks Case Study Leaks by Percent of CFM 6% 5% 29% 6% 8% 13% 20% 13% Fitting FRL Valve Blowgun Cylinder Coupling Hose Other
Leaks Detection What a lot of Flow Meters work! Flow Meters tell us that Parabolic Dish and Ultrasonic Leak Detector leaks have developed. Now we need to know where they are!
Leaks Conventional Detection Compressed Air Audit Tool of Choice – Ultrasonic Leak Detector Expensive Pack In, Pack Out…Hassle Auditing Expensive, but… • Leak repair savings usually recover cost Time-consuming • Auditor examines plant-wide system Conducted once or twice yearly • Customer pays every time • Report can be overwhelming
Leaks Automatic Leak Detection System Goals Decrease detection cost • Fewer man hours • Lower skill requirement • Lower cost equipment Increased detection frequency • Minimizes leak impact Rapidly pinpoint leaks Accurate leakage value (as low as .07 SCFM)
Leaks ALDS Concept - Implementation Hardware Flow Meter and Diverter Valve Installed in machine’s main air supply line Software Written in the machine’s PLC Runs leak detection sub- routine
Leaks ALDS Advantages
Non-Productive Use of Air
Non-Productive Use of Air Air Blow Common Applications Contaminate removal Drying Air-blow has the potential to be the most Open blow Part transfer wasteful end- use- application of compressed air.
Non-Productive Use of Air Air Blow Improvement Reduce pressure loss and air consumption while maintaining work surface impact. High-efficiency nozzle With Nozzle 100 PSI 100 PSI Pressure Loss is minimal Without Nozzle 100 PSI 60 PSI 20 PSI Pressure loss is great
Non-Productive Use of Air Air Blow Solutions Nozzle Pressure Impact Air Flow Diameter before nozzle Pressure Rate mm PSIG Distance PSIG SCFM Current 4 3 4" 0.25 4 Improved 2 13 4" 0.25 2 Improved 1 30 4" 0.25 1
Non-Productive Use of Air Air Blow High Pressure Solutions A great amount of money can be saved on blow-off applications by using high efficiency nozzles, regulation and effective tube to nozzle ratios, while maintaining the same impact work pressures required for the job. The ratio of effective area and pressure High-Efficiency Blow Gun
Non-Productive Use of Air Air-Blow Solutions Momentary positive pressure Appropriate tubing size Auto shut off when not in use Reduce to the lowest effective Venturi style nozzles pressure
Non-Productive Use of Air Design Alternatives • Primary Considerations – Cylinder Sizing – Double Acting vs. Single Acting – Regenerative Circuits – Tubing length: Filling tube with no benefit – Pressure Control
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