1、Lowering Your Compressed Air Energy Costs Trey DonzeMike HotzAir TechnologiesWhy Care About Compressed Air?Compressed air is expensive Compressed air is essential to plant productivity Compressed air systems can be effectively managed to improve plant operation Compressed air systems usually have si
2、gnificant opportunities for efficiency improvementCompressed Air Use in Selected Manufacturing IndustriesCompressed Air Energy Use as a Percentage of Total Electricity UseChemicalsPetroleumMetalsFoodPaperLife Cycle Cost of an air compressorlEnergy cost can account for up to 90%over a ten year workin
3、g lifelWithin 12 months,the capital cost is usually exceeded by the running costslFirst cost represents the lowest of the three costslEnergy consumption by far is the most significant factor in operating cost of an air compressorInvestmentInstallationMaintenanceEnergy consumptionlTo make an accurate
4、 determination of energy savings solutions,it is important to measure your system flow,pressure and kW as well as evaluate any plans for future expansionlThis is accomplished by a flow and kW survey Benchmark Your Systems Efficiency Measure your compressed air requirements Flow Pressure Dew point kW
5、 and kWh Benchmark your current systems efficiency kWh/MCF Receive a detailed report outlining improvementsBenchmark Your Systems EfficiencyKW MeterslTypical 24 hrs/day operation with low night shift and high day shift consumption.Steady weekend consumption(leakages).l(64%of installations).timelFive
6、 days/week operation,erratic demand fluctuations l(28%of installations).timeEnergy Reduction Opportunities Use Efficient Compressor Controls Reduce Compressed Air Usage Lower Compressor Discharge Pressure Efficiently Sequence Air Compressors Operate and Maintain Compressed Air Equipment at Peak Effi
7、ciencyPerformance ComparisonTotal KW Input-vs-Capacity01020304050607080901000102030405060708090100A)Modulation ControlB)Active Rotor Length Adj.C)Full Load/No LoadD)VSDABCD%Capacity%Power Input75 HP Lubricated screw compressor w/Modulation Control-vs.-60 HP VSDAverage electrical cost=$0.06/KWHRA)1st
8、 shift250 CFM2200 HRS/YRB)2nd shift175 CFM2200 HRS/YRC)3rd shift100 CFM2200 HRS/YR75 HP unit 125 PSIG60HP VSD 125 PSIG82.5 Bhp full load power66 Bhp full load power320 CFM 290 CFM91.5%Motor eff.94%Use Efficient Compressor ControlsPerformance ComparisonTotal KW Input-vs-Capacity0.010.020.030.040.050.
9、060.070.080.0050100150200250300350Capacity(CFM)Total KW Input60 HP VSD75 HP w/Upper range modulation controlUse Efficient Compressor Controls75 Hp modulating60 Hp VSD250 CFM:250/320=78%(93%Bhp)250/290=86%(86%Input kW)175 CFM:175/320=55%(86.5%Bhp)175/290=60%(61%Input kW)100 CFM:100/320=31%(79%Bhp)100
10、/290=34%(38%Input kW)Use Efficient Compressor Controls75 HP lubricated screw with modulation controlA)First shift 250 CFM:82.5 Bhp X(.93 factor)X.746kW X$.06 X 2200Hrs=$8,738.915 Mtr.eff.Hp kWhB)Second shift175 CFM:82.5 Bhp X(.865 factor)X.746kW X$.06 X 2200Hrs=$8,127.915 Mtr.eff.Hp kWhC)Third shift
11、 100 CFM:82.5 Bhp X(.79 factor)X.746kW X$.06 X 2200Hrs=$7,422.915 Mtr.eff.Hp kWh Total =$24,287Use Efficient Compressor Controls60 Hp Variable Speed compressorA)First shift250 CFM:66 Bhp x.746 kW x(.86 factor)x$.06 x 2200Hrs=$5,946.94 ME.HpkWhB)Second shift 175 CFM:66 Bhp x.746 kW x(.61 factor)x$.06
12、 x 2200Hrs=$4,217.94 ME HpkWhC)Third shift100 CFM:66 Bhp x.746 kW x(.38 factor)x$.06 x 2200Hrs=$2,627.94 ME Hp kWhTotal=$12,790Total Power Savings:$24,287-$12,790=$11,497 per year60 HP VSD costs$25,000 for a 2.17 year payback!Use Efficient Compressor ControlsSystem running with(2)-125 HP OL/OL compr
13、essors 3.7 kWH/MCFInconsistent efficiencySystem running with(1)-125 HP OL/OL compressors and(1)-75 HP VSD3.3 kWH/MCFNearly constant efficiencyReduce Compressed Air Usage Eliminate inappropriate air users Use brushes,blowers,or vacuum systems instead of compressed air to clean parts or remove debris;
14、Use blowers,electric actuators,or hydraulics instead of compressed air blasts to move parts;Use high efficiency nozzles instead of open orificesReduce Compressed Air Usage Eliminate inappropriate air users Use fans to cool electrical cabinets instead of compressed air vortex tubes Apply a vacuum sys
15、tem instead of using compressed air venturi methods Use blowers instead of compressed air to provide cooling,aspirating,blow guns,air lances,agitating,mixing,or to inflate packagingReduce Compressed Air Usage Minimize unregulated air users Install regulators Reduced pressure lowers air consumption U
16、nregulated users use 47%more compressed air at 110 vs.70 PSIG Less equipment wear and tearAir PressureFlow ratePSIGSCFM5058.26067707680859094100103110112120121Reduce Compressed Air Usage Shut off air to equipment that is shutdown or abandoned Install automatic solenoid valves Valve off idled section
17、s of the plantReduce Compressed Air Usage Fix Leaks Leaks can account for 10-50%of the total compressed air usage!1/8 inch dia.hole=25 SCFM=$3,0001/4 inch dia.hole=100 SCFM =$12,0003/8 inch dia.hole=230 SCFM=$26,000*Based on 8,760 operating hrs/yr$0.07 per kWh energy costReduce Compressed Air Usage
18、Minimize Leaks Measure leak load to quantify the opportunity Find the leaks with an ultrasonic leak detector Tag the leaks Fix the leaks Re-measure the leak load to quantify the savings Develop and on-going leak reduction programReduce Compressed Air Usage Reduce plant system air pressure Unregulate
19、d air users and air leaks use 28%more compressed air at 120 vs.90 PSIGAir PressureFlow ratePSIGSCFM5058.26067707680859094100103110112120121Reduce Compressed Air Usage Reduce system air pressure Evaluate the pressure requirements of all compressed air users Put the small high pressure user on its own
20、 compressor Install good compressor sequencing controls Lower the system air pressureReduce System Air Pressure Measure system/component pressure drops Minimize distribution and component pressure drops Loop air header Upgrade,repair or eliminate high delta P components Upsize piping/hoses Address l
21、arge intermittent air“gulpers”that draw the system down with storage and metering valves Decentralize compressorsReceiver Sizing Useful Free Air Stored=V x P 14.7 V=storage volume(Ft3)P=pressure differential(Pressure Drop in Tank)Example:Pneumatic conveyor requires 200 cfm of 40 psig air for 2 minut
22、es every 10 minutes.200 X 2=400 CF required useful free air to be stored P=100-40=60400=V X 60/14.7 V=400 X 14.7/60=98 CF=735 gallons400 CF/8 minutes=50 CFM to refillSystem sees 50 CFM instead of 200 CFM!Lower System Pressure to Lower Air Consumption70 psig 700 CFM air usage85 psig 825 CFM air usage
23、95 psig 950 CFM air usageReduce Compressed Air Usage Reduce system air pressure Use intermediate controllers with storage to regulate system air pressure Effective when part of the plant operates at a lower pressure Lowers air consumption Does not lower compressor pressureReduce Compressed Air Usage
24、 Reduce system air pressure Use effective compressor sequencing,storage,and compressor controls to“regulate”system pressure Lowers air consumption and compressor pressure Most energy efficientSequence Air CompressorsTypical System Without a SequencerCascading SystemsC1C2C3C4unloadloadlIndividual set
25、tingslLarge pressure bandlMultiple units at part loadlVery inefficient100 PSIG110105115110120115125 PSIG125100Sequencers Significantly Improve Efficiency to Minimize Energy Costs Can regulate system pressure within 3-5 psi Lower system pressure significantly reduces air demand(leaks and unregulated
26、demand)Operates the minimum#of compressors to meet the demand Only one compressor trims at all times Automatic scheduled system pressure changes and/or start/stop of system Most efficient compressor sequence order determined from flow data Can automatically select optimum sequenceSystem Pressure rem
27、ains consistent as flow rate variesPower consumption increases 1%for every 2 psi increase in compressor pressure RULE OF THUMBEXAMPLE-4-100 Hp Compressors Required:1700 SCFM at 100 Psig Pressure Switch Settings Between 95 to 125Psig Pressure Band of 30 Psig 400 Hp x.745 kW/Hp x 8800/year x.06 kWh=$1
28、67,387.00.94(motor Efficiency)Reduce Pressure Band by 25 Psig to save 12%=$20,086.00 Sequencers pay for themselves in energy savings by reducing pressure band differentials and lowering air usageFlow changes but kW does not change proportionally0200400600800100012001400160018001611162126313641465156
29、6166717681869196101106111116121126131136MEC_SCFMTotal KwPoor efficiency of a cascaded system due to multiple units at part loadkWh/100CF-0.10.10.30.50.70.91.11.31.51.00954.001907.002860.003813.004766.005719.006672.007625.008578.009531.0010484.0011437.0012390.0013343.0014296.0015249.0016202.0017155.0
30、018108.0019061.0020014.0020967.0021920.0022873.0023826.0024779.0025732.0026685.00kWh/100CFSequencers Can Significantly Improve Efficiency to Minimize Energy CostsTotal system energy savings of 20-50%are expected kW/100 CF stays consistent even under varying loads.32 kW/100CF versus.85 kW/100CF(63%Sa
31、vings!)Switch to LILO Sequencing with a 5 minute unloaded timeTotal Anual Savings!$15,347$30,695$122,778$61,389$0$20,000$40,000$60,000$80,000$100,000$120,000$140,000100200400800Total System HorsepowerSequencing Significantly Improves Efficiency to Minimize Energy CostsBasis 3 shift operation,$.06/kW
32、hr,20 PSI pressure band reduction%Savings100200400800Tighter Pressure Band10%$4,235$8,471$16,941$33,883Reduced Unregulated Demand/Leaks6%$2,541$5,082$10,165$20,330More Efficient Sequencing20%$8,471$16,941$33,883$67,766Total Estimated Savings!36%$15,347$30,695$61,389$122,778Total System Horsepower Sy
33、stem flow and pressure are logged automatically Determine the most efficient compressor sequence Useful for peak load shedding Measure leaks Spot system/production problems Measure equipment/process air consumptionAdvanced sequencers provide system flow and pressure data to manage your 4th Utility M
34、anagAIR by Air Technologies System Report for Ferro 9/7/01 1:59:05 PMAlarm:No Faults DetectedCurrent System Readings-Pressure=108 Flowrate=1347 Sequence=2,1,3Previous 8hrs Data:Hour1 Hour2 Hour3 Hour4 Hour5 Hour6 Hour7 Hour8 Min Pressure 104 104 104 104 104 104 104 104Avg Pressure 108 108 109 109 10
35、9 109 109 109Max Pressure 114 114 114 114 114 114 114 114Min FlowRate 1274 1274 1311 1322 1324 1349 1311 1305Avg FlowRate 1448 1468 1648 1647 1739 1870 1644 1718Max FlowRate 2274 2298 2504 2485 2545 2629 2409 2432Min DewPoint -44 -43 -43 -43 -40 -36 -32 -21Avg DewPoint -41 -41 -36 -40 -37 -33 -25 -1
36、5Max DewPoint -39 -39 -11 -37 -35 -30 -19 -10Compressor Data#1 ZT25#2 ZT25#3 ZT25 NONE NONE NONE NONE Delivery Air Press 110 113 107 DP Air Filter -.01 -.1 .01 Intercooler Pressure -9 30 1 Oil Injection Press 28 28 0 Delivery Air Temp 93 93 86 Oil Injection Temp 122 124 90 LP Outlet Temp 351 352 95
37、HP Outlet Temp 363 372 91 HP Inlet Temp 99 104 91 Cooling Medium Inlet Temp 91 91 86 MD Regen Air Out Temp 129 162 84 MD Wet Air In Temp 97 99 81 LP Element Temp Rise 260 261 9 HP Element Temp Rise 264 268 0 Cooling Water Temp Rise Oil Cooler Approach Temp 31 33 4 Aftercooler Approach Temp 2 2 0 Int
38、ercooler Approach Temp 8 13 5 MD Regen Temperature Drop 234 210 7 MD Inlet Temperature Diff 4 6 -5 Loaded Hours 7358 7579 8773 Running Hours 11048 11616 12606 Compressor Status UNLOADED LOADED STOPPED Motor Starts 1717 1042 1060 Link Type MKIII MKIII MKIII Isolated/Integrated CENTRAL CENTRAL CENTRAL
39、 Full Feature Dew Point Oil Filter Remaining Lifetime 2423 1413 952 Oil Filter Total Lifetime 4000 4000 4000 Oil Remaining Lifetime 4952 4383 3475 Oil Total Lifetime 16000 16000 16000 Hours Until Regrease Bearings 848 286 3471 Hours Between Bearing Regreasing 4000 4000 4000 Daily System Report and g
40、raph faxed or e-mailed to you automaticallyInlet Filters Every 4 inches(water)pressure drop reduces the compressor capacity 1%A dirty inlet filter can rob you of 5%or more!Good Maintenance Saves EnergyDirty Coolers For every 11oF deterioration in the intercooler approach or increase in water tempera
41、ture,the power consumption will increase by 1%.Good Maintenance Saves EnergyFor every 10oF deterioration of the after cooler approach temperature,the dryer load is increased by as much as 46%.Dirty CoolersGood Maintenance Saves EnergyA dirty oil separator can increase your HP 5%Dirty Oil SeparatorGo
42、od Maintenance Saves EnergyEnergy Reduction Opportunities Use Efficient Compressor Controls Reduce Compressed Air Usage Lower Compressor Discharge Pressure Efficiently Sequence Air Compressors Operate and Maintain Compressed Air Equipment at Peak EfficiencyLowering Your Compressed Air Energy Costs Trey DonzeMike Hotz Air Technologies513-539-6747
