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Compressor and compressed_air_systems

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Compressor and compressed_air_systems

  1. 1. Training Session on Energy Equipment Compressors &Electrical Equipment/ Compressed Air Compressors Systems Presentation from the “Energy Efficiency Guide for Industry in Asia” www.energyefficiencyasia.org 1 © UNEP 2006
  2. 2. Training Agenda: Compressor IntroductionElectrical Equipment/ Types of compressors Compressors Assessment of compressors and compressed air systems Energy efficiency opportunities 2 © UNEP 2006
  3. 3. Introduction Significant Inefficiencies • Compressors: 5 to > 50,000 hpElectrical Equipment/ • 70 – 90% of compressed air is lost Compressors 3 (McKane and Medaris, 2003) © UNEP 2006
  4. 4. Introduction Benefits of managed systemElectrical Equipment/ • Electricity savings: 20 – 50% Compressors • Maintenance reduced, downtime decreased, production increased and product quality improved (eCompressedAir) 4 © UNEP 2006
  5. 5. Introduction Main Components in CompressedElectrical Equipment/ Air Systems Compressors • Intake air filters • Inter-stage coolers • After coolers • Air dryers • Moisture drain traps • Receivers 5 © UNEP 2006
  6. 6. Training Agenda: Compressor IntroductionElectrical Equipment/ Types of compressors Compressors Assessment of compressors and compressed air systems Energy efficiency opportunities 6 © UNEP 2006
  7. 7. Types of Compressors Two Basic Compressor TypesElectrical Equipment/ Compressors Type of compressor Positive Dynamic displacement Reciprocating Rotary Centrifugal Axial 7 © UNEP 2006
  8. 8. Types of Compressors Reciprocating CompressorElectrical Equipment/ • Used for air and refrigerant compression • Works like a bicycle pump: cylinder volume reduces Compressors while pressure increases, with pulsating output • Many configurations available • Single acting when using one side of the piston, and double acting when using both sides (King, Julie) 8 © UNEP 2006
  9. 9. Types of Compressors Rotary CompressorElectrical Equipment/ • Rotors instead of pistons: continuous discharge Compressors • Benefits: low cost, compact, low weight, easy to maintain • Sizes between 30 – 200 hp • Types • Lobe compressor • Screw compressor Screw compressor • Rotary vane / Slide vane 9 © UNEP 2006
  10. 10. Types of Compressors Centrifugal CompressorElectrical Equipment/ • Rotating impeller Compressors transfers energy to move air • Continuous duty • Designed oil free • High volume applications > 12,000 cfm 10 (King, Julie) © UNEP 2006
  11. 11. Types of Compressors Comparison of CompressorsElectrical Equipment/ • Efficiency at full, partial and no load Compressors • Noise level • Size • Oil carry-over • Vibration • Maintenance • Capacity • Pressure 11 © UNEP 2006
  12. 12. Training Agenda: Compressor IntroductionElectrical Equipment/ Types of compressors Compressors Assessment of compressors and compressed air systems Energy efficiency opportunities 12 © UNEP 2006
  13. 13. Assessment of Compressors Capacity of a CompressorElectrical Equipment/ • Capacity: full rated volume of flow of Compressors compressed gas • Actual flow rate: free air delivery (FAD) • FAD reduced by ageing, poor maintenance, fouled heat exchanger and altitude • Energy loss: percentage deviation of FAD capacity 13 © UNEP 2006
  14. 14. Assessment of Compressors Simple Capacity Assessment MethodElectrical Equipment/ • Isolate compressor and receiver and close receiver outlet Compressors • Empty the receiver and the pipeline from water • Start the compressor and activate the stopwatch • Note time taken to attain the normal operational pressure P2 (in the receiver) from initial pressure P1 • Calculate the capacity FAD: P2 = Final pressure after filling (kg/cm2a) P1 = Initial pressure (kg/cm2a) after bleeding) P0 = Atmospheric pressure (kg/cm2a) V = Storage volume in m3 which includes receiver, after cooler and delivery piping T = Time take to build up pressure to P2 in minutes 14 © UNEP 2006
  15. 15. Assessment of Compressors Compressor EfficiencyElectrical Equipment/ • Most practical: specific power Compressors consumption (kW / volume flow rate) • Other methods • Isothermal • Volumetric • Adiabatic • Mechanical 15 © UNEP 2006
  16. 16. Assessment of Compressors Compressor EfficiencyElectrical Equipment/ Isothermal efficiency Compressors Isothermal efficiency = Actual measured input power / Isothermal power Isothermal power (kW) = P1 x Q1 x loger / 36.7 P1 = Absolute intake pressure kg / cm2 Q1 = Free air delivered m3 / hr r = Pressure ratio P2/P1 16 © UNEP 2006
  17. 17. Assessment of Compressors Compressor EfficiencyElectrical Equipment/ Volumetric efficiency Compressors Volumetric efficiency = Free air delivered m3/min / Compressor displacement Compressor displacement = Π x D2/4 x L x S x χ x n D = Cylinder bore, meter L = Cylinder stroke, meter S = Compressor speed rpm χ = 1 for single acting and 2 for double acting cylinders 17 n = No. of cylinders © UNEP 2006
  18. 18. Assessment of Compressors LeaksElectrical Equipment/ • Consequences Compressors • Energy waste: 20 – 30% of output • Drop in system pressure • Shorter equipment life • Common leakage areas • Couplings, hoses, tubes, fittings • Pressure regulators • Open condensate traps, shut-off valves • Pipe joints, disconnects, thread sealants 18 © UNEP 2006
  19. 19. Assessment of Compressors Leak Quantification MethodElectrical Equipment/ Compressors • Total leakage calculation: Leakage (%) = [(T x 100) / (T + t)] T = on-load time (minutes) t = off-load time (minutes) • Well maintained system: less than 10% leakages 19 © UNEP 2006
  20. 20. Assessment of Compressors Quantifying leaks on the shop floorElectrical Equipment/ • Shut off compressed air operated equipments Compressors • Run compressor to charge the system to set pressure of operation • Note the time taken for “Load” and “Unload” cycles • Calculate quantity of leakage (previous slide) • If Q is actual free air supplied during trial (m3/min), then: System leakage (m3/minute) = Q × T / (T + t) 20 © UNEP 2006
  21. 21. Assessment of Compressors ExampleElectrical Equipment/ • Compressor capacity (m3/minute) = 35 Compressors • Cut in pressure, kg/cm2 = 6.8 • Cut out pressure, kg/cm2 = 7.5 • Load kW drawn = 188 kW • Unload kW drawn = 54 kW • Average ‘Load’ time =1.5 min • Average ‘Unload’ time = 10.5 min Leakage = [(1.5)/(1.5+10.5)] x 35 = 4.375 m3/minute 21 © UNEP 2006
  22. 22. Training Agenda: Compressor IntroductionElectrical Equipment/ Types of compressors Compressors Assessment of compressors and compressed air systems Energy efficiency opportunities 22 © UNEP 2006
  23. 23. Energy Efficiency Opportunities 1. LocationElectrical Equipment/ • Significant influence on energy use Compressors 2. Elevation • Higher altitude = lower volumetric efficiency 23 © UNEP 2006
  24. 24. Energy Efficiency Opportunities 3. Air IntakeElectrical Equipment/ • Keep intake air free from Compressors contaminants, dust or moist • Keep intake air temperature low Every 4 oC rise in inlet air temperature = 1% higher energy consumption • Keep ambient temperature low when an intake air filter is located at the compressor 24 © UNEP 2006
  25. 25. Energy Efficiency Opportunities 4. Pressure Drops in Air FilterElectrical Equipment/ • Install filter in cool location or draw Compressors air from cool location • Keep pressure drop across intake air filter to a minimum Every 250 mm WC pressure drop = 2% higher energy consumption 25 © UNEP 2006
  26. 26. Energy Efficiency Opportunities 5. Use Inter and After CoolersElectrical Equipment/ • Inlet air temperature rises at each Compressors stage of multi-stage machine • Inter coolers: heat exchangers that remove heat between stages • After coolers: reduce air temperature after final stage • Use water at lower temperature: reduce power 26 © UNEP 2006
  27. 27. Energy Efficiency Opportunities 6. Pressure SettingsElectrical Equipment/ • Higher pressure Compressors • More power by compressors • Lower volumetric efficiency • Operating above operating pressures • Waste of energy • Excessive wear 27 © UNEP 2006
  28. 28. Energy Efficiency Opportunities 6. Pressure SettingsElectrical Equipment/ a. Reducing delivery pressure Operating a compressor at 120 PSIG instead of 100 Compressors PSIG: 10% less energy and reduced leakage rate b. Compressor modulation by optimum pressure settings Applicable when different compressors connected c. Segregating high/low pressure requirements 28 Pressure reducing valves no longer needed © UNEP 2006
  29. 29. Energy Efficiency Opportunities 6. Pressure SettingsElectrical Equipment/ d. Design for minimum pressure drop in the distribution line Compressors • Pressure drop: reduction in air pressure from the compressor discharge to the point of use • Pressure drop < 10% • Pressure drops caused by • corrosion • inadequate sized piping, couplings hoses • choked filter elements 29 © UNEP 2006
  30. 30. Energy Efficiency Opportunities 6. Pressure SettingsElectrical Equipment/ d. Design for minimum pressure drop in Compressors the distribution line Typical pressure drop in compressed air line for different pipe size (Confederation of Indian Industries) 30 © UNEP 2006
  31. 31. Energy Efficiency Opportunities 7. Minimizing LeakageElectrical Equipment/ • Use ultrasonic acoustic detector Compressors • Tighten joints and connections • Replace faulty equipment 8. Condensate Removal • Condensate formed as after-cooler reduces discharge air temperature • Install condensate separator trap to remove condensate 31 © UNEP 2006
  32. 32. Energy Efficiency Opportunities 9. Controlled usageElectrical Equipment/ • Do not use for low-pressure Compressors applications: agitation, combustion air, pneumatic conveying • Use blowers instead 10. Compressor controls • Automatically turns off compressor when not needed 32 © UNEP 2006
  33. 33. Energy Efficiency Opportunities 9. Maintenance PracticesElectrical Equipment/ • Lubrication: Checked regularly Compressors • Air filters: Replaced regularly • Condensate traps: Ensure drainage • Air dryers: Inspect and replace filters 33 © UNEP 2006
  34. 34. Training Session on Energy Equipment Electrical Equipment/ Compressors & Compressors Compressed Air Systems THANK YOU FOR YOUR ATTENTION 34 © UNEP GERIAP
  35. 35. Disclaimer and References • This PowerPoint training session was prepared as part of the project “Greenhouse Gas Emission Reduction fromElectrical Equipment/ Industry in Asia and the Pacific” (GERIAP). While reasonable efforts have been made to ensure that the Compressors contents of this publication are factually correct and properly referenced, UNEP does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. © UNEP, 2006. • The GERIAP project was funded by the Swedish International Development Cooperation Agency (Sida) • Full references are included in the textbook chapter that is 35 available on www.energyefficiencyasia.org © UNEP 2006

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