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Compressed Air Technology – Concept Compressed Air Background Important industrial energy source Inherently inefficient Consumes up to 20% of industrial electrical usage $$$ Great energy & cost savings potential! Lifetime Operation vs. First Cost
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Compressed Air Technology – Concept
Compressed Air Background • Important industrial energy source • Inherently inefficient • Consumes up to 20% of industrial electrical usage $$$ Great energy & cost savings potential! US DOE – Industries of the Future Workshop Series
Lifetime Operation vs. First Cost Typical Lifetime Compressed Air Costs Over 10 years Assumptions include a 75-hp compressor operated two shifts, 5 days a week at an aggregate electric rate o $0.05/kWh over 10 years of equipment life. Source: US Dept of Energy, Office of Industrial Technologies: Compressed Air Tip sheet #1. http://www.oit.doe.gov/bestpractices/pdfs/compressed_air1.pdf US DOE – Industries of the Future Workshop Series
} One horsepower of compressed air yields . . . Compressed Air Energy • Inefficient power source even if well maintained Eight compressor horsepower US DOE – Industries of the Future Workshop Series
Compressed Air Energy Ratio: 8:1 US DOE – Industries of the Future Workshop Series
Supply Compressor System Controls Air Dryer Aftercoolers Air Filters Primary Storage Flow controls Distribution Air piping Filters, lubricators, regulators End Uses Pneumatic tools Mechanical drive Blowers Vacuum generators Etc . . . Compressed Air System US DOE – Industries of the Future Workshop Series
Supply – compressor types US DOE – Industries of the Future Workshop Series
Supply – compressors • Reciprocating • Very efficient • Requires frequent maintenance • Can be equipped for very efficient part loading • Can be multistaged US DOE – Industries of the Future Workshop Series
Supply – compressors • Rotary Screw • Easy to install • Enables modulation control • Easy to maintain • Can be single or double staged Source: Gardner Denver US DOE – Industries of the Future Workshop Series
(Outlet modulation) (Inlet) On/Off (not pictured) (Inlet) Supply – control types US DOE – Industries of the Future Workshop Series
Variable Speed Drive Compressors • Allows precise matching of supply and demand • Extremely efficient at low load • Less efficient that standard compressors at full load • Retrofitting standard compressors is problematic • Not ideal for every application • Best for precise constant pressure applications US DOE – Industries of the Future Workshop Series
Supply – dryers • Refrigerated dryers • Utilized mechanical cooling • Air dew point limited by water freezing point (35º -40º F) • Relatively inexpensive • Generates condensate Source: Smargon US DOE – Industries of the Future Workshop Series
Regenerative desiccant Water vapor is adsorbed by desiccant fill Low air dew points (-40ºF to -100ºF Heated or unheated Requires 3-15% purge air No condensate generated Supply – dryers Source: Palatek US DOE – Industries of the Future Workshop Series
Efficient compressed air systems • Proper performance yields • Low operating costs • Minimal downtime • Clean, dry, dependable air • Effective process control US DOE – Industries of the Future Workshop Series
Save energy (25% or more) • Reduce downtime • Produce clean, dry air • Eliminate maintenance crises $$$ Why make a change? Great energy & cost savings potential! US DOE – Industries of the Future Workshop Series
Benchmarking • Determine average power draw (kW) • Determine total energy costs • Determine marginal generation efficiency (kW/scfm) • Calculate energy savings potential for system improvements • Worksheet “Estimate Your Compressed Air Cost” US DOE – Industries of the Future Workshop Series
Common problem areas • Air Leaks • No heat recovery • High pressure drop • Insufficient air storage • Ineffective control strategy • Multiple compressor operation not optimized • Base load vs. trim compressor • Inappropriate end uses • Poor record keeping • Electric usage • Air production US DOE – Industries of the Future Workshop Series
When was your last leak survey? Poorly maintained systems Up to 40% leak rate Pressure problems “We need to install another compressor.” Air leaks Leak surveys should be conducted quarterly! US DOE – Industries of the Future Workshop Series
Heat recovery } 8 compressor horsepower yields 1 horsepower of compressed air . . . Where does the other 7 horsepower go???? HEAT. US DOE – Industries of the Future Workshop Series
Heat recovery • 80% of compressor input power may be recoverable • Possible uses • Space heating • Hot water heating • Drying/curing room heating • Heat source for desiccant dryer • 100 hp @ full load 300,000 Btu/hr US DOE – Industries of the Future Workshop Series
Winter Operation Compressor Hot air to Plant Heat recovery US DOE – Industries of the Future Workshop Series
Hot air Exhausted Summer Operation Compressor Heat recovery US DOE – Industries of the Future Workshop Series
High ΔP filters Short radius elbows “Tee” junctions Unnecessary piping High ΔP dryer Pressure drop – compressor room US DOE – Industries of the Future Workshop Series
Pressure drop (continued) • Distribution • Worksheet “Calculating the Cost of High Pressure Drop” GOAL:0 – 4 psig pressure drop in compressor room US DOE – Industries of the Future Workshop Series
Rule of Thumb – 4 gallons of storage per compressor cfm Remote storage for high periodic demands Wet vs. dry storage Piping rule In at the bottom – Out at the top! Air storage US DOE – Industries of the Future Workshop Series
Air Storage – Compressor Loading 100 hp compressor with load/unload controls Loaded Blow down Unloaded Unloaded US DOE – Industries of the Future Workshop Series
Average Power = 82.9 kW Air Storage – Compressor Loading Inadequate Storage (1 gal/cfm) Compressor is fully loaded (delivering air) for 130 seconds US DOE – Industries of the Future Workshop Series
Average Power = 63.0 kW Air Storage – Compressor Loading Improved Storage (3 gal/cfm) Compressor is fully loaded (delivering air) for 130 seconds US DOE – Industries of the Future Workshop Series
Energy Savings Air Storage Generalized energy savings for increased storage in load/unload compressors US DOE – Industries of the Future Workshop Series
Compressor controls • Control strategies impact compressor energy consumption US DOE – Industries of the Future Workshop Series
Compressor controls • “Using the Most Efficient Control Strategy” worksheet US DOE – Industries of the Future Workshop Series
Inappropriate End Uses • Anything that can be done… • More effectively by another method • More efficiently by another method US DOE – Industries of the Future Workshop Series
Inappropriate End Uses - Examples • Open blowing - Cooling, drying, clean-up • Sparging - Aerating, agitating, oxygenating, percolating • Aspirating - Inducing flow in another gas (e.g., flue gases) • Atomizing - Dispersing or delivering a liquid to a process as an aerosol • Dilute phase transport - Transporting solids such as powders • Dense phase transport - Transporting solids in batches continued… US DOE – Industries of the Future Workshop Series
Inappropriate End Uses - Examples • Vacuum generation - used with a venturi to generate negative pressure mass flow • Personnel cooling • Open blowguns or lances • Diaphragm pumps • Cabinet cooling US DOE – Industries of the Future Workshop Series
Application of new technologies/concepts • Variable speed compressors • Zero loss drains • Air amplifying nozzles • Solenoid shut off valves • Demand Controller US DOE – Industries of the Future Workshop Series
Timer drains either: Waste air Fail to remove all liquid Zero loss drains remove liquid with no air loss Zero Loss Drains US DOE – Industries of the Future Workshop Series
Amplifiers entrain still air to increase air flow from blowing components Advantages Increase blowing force Significantly reduced compressed air usage Reduced noise Fully adjustable Applications • Air curtains/knives • Hand blow guns • Blow off manifolds Air Amplifiers Source: ARTX US DOE – Industries of the Future Workshop Series
Reduce leaks in piping to equipment that is shut off Timer control Machine panel control Manual control Electric Solenoid Valves US DOE – Industries of the Future Workshop Series
Demand Controllers • Isolate supply side from demand side of system • Appropriate only with adequate storage • Help reduce air usage by minimizing pressure delivered to end users Source: Zeks Compressed Air Solutions US DOE – Industries of the Future Workshop Series
Implementation requires participation Production Maintenance Management Improving system performance Assessing the entire system Identifying opportunities Quantifying benefits and costs Implementing most feasible projects How do I optimize the performance of my compressed air system? • Systems approach (supply and demand) US DOE – Industries of the Future Workshop Series
IAC implementation trends and analysis US DOE – Industries of the Future Workshop Series
How to start • Steps in evaluating your system • Monitoring needs • Best Practices • Pitfalls Treat compressed air like a fourth utility. US DOE – Industries of the Future Workshop Series
Steps to Evaluate Your System • Determine the cost of your air • Check for air leaks • Replace all dirty filters with high efficiency filters • Set efficient control strategies • Base loaded compressors – modulating control • Trim compressors – Load/unload control • Pressure issues • Check that all end use pressures are regulated • Check for excessive generation pressure (<10 psi drop between compressor and highest end user) • Address inappropriate end uses • Check for adequate storage (>3 gal/cfm) • Shut down idle compressors • Check for moisture in storage tanks and drip legs US DOE – Industries of the Future Workshop Series
Monitoring • Air Pressure Problems • Compressor Loading • Power consumption • Air Consumption • Track using MS Excel or similar program US DOE – Industries of the Future Workshop Series
Pitfalls • Running at too high a pressure • Considering compressed air as a free utility • Higher pressure = more air • Adding compressor horsepower to combat pressure problems • Always have a compressed air audit completed before adding additional compressors. • Inadequate storage/piping US DOE – Industries of the Future Workshop Series
ISO 14000 • Formalized method for identifying and documenting process improvements • Can be used for benchmarking • Proper use can lead to significantly reduced energy costs • All program goals are set by company • Benchmarking US DOE – Industries of the Future Workshop Series
Re-Assess Goals Benchmarking revisited • Benchmarking should be part of a larger plan Commit to Continuous Improvement Implement Action Plan Create Action Plan Assess Performance Set Goals Evaluate Progress US DOE – Industries of the Future Workshop Series
In house assessment • Tools available from US DOE Air Challenge Program • US DOE Industrial Assessment Centers • Energy Resources Center @ UIC • Private energy service companies Assessing Resources GO TO Compressed Air Resource List • Equipment manufacturers US DOE – Industries of the Future Workshop Series