Lowering Your Compressed Air Energy Costs

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Lowering Your Compressed Air Energy Costs

• Trey Donze
• Mike Hotz
• Air Technologies

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Why 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 significant
  opportunities for efficiency improvement

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Compressed Air Use in Selected Manufacturing
Industries
Compressed Air Energy Use as a Percentage of
Total Electricity Use
Food
Metals
Paper
Petroleum
Chemicals
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Life Cycle Cost of an air compressor

• Energy cost can account for up to 90 over a ten
  year working life
• Within 12 months, the capital cost is usually
  exceeded by the running costs
• First cost represents the lowest of the three
  costs
• Energy consumption by far is the most significant
  factor in operating cost of an air compressor

Energy consumption
Installation
Maintenance
Investment
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Benchmark Your Systems Efficiency

• To make an accurate determination of energy
  savings solutions, it is important to measure
  your system flow, pressure and kW as well as
  evaluate any plans for future expansion
• This is accomplished by a flow and kW survey

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Benchmark Your Systems Efficiency

• Measure your compressed air requirements
• Flow
• Pressure
• Dew point
• kW and kWh
• Benchmark your current systems efficiency
  kWh/MCF
• Receive a detailed report outlining improvements

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KW Meters
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• Typical 24 hrs/day operation with low night shift
  and high day shift consumption. Steady weekend
  consumption (leakages).
• (64 of installations).

time
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• Five days/week operation, erratic demand
  fluctuations
• (28 of installations).

time
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Energy 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 Efficiency

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Power Input
Capacity
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Use Efficient Compressor Controls

• 75 HP Lubricated screw compressor
• w/ Modulation Control -vs.- 60 HP VSD
• Average electrical cost 0.06 / KWHR
• A) 1st shift 250 CFM 2200 HRS/YR
• B) 2nd shift 175 CFM 2200 HRS/YR
• C) 3rd shift 100 CFM 2200 HRS/YR
• 75 HP unit _at_ 125 PSIG 60HP VSD _at_ 125 PSIG
• 82.5 Bhp full load power 66 Bhp full load
  power
• 320 CFM 290 CFM
• 91.5 Motor eff. 94

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Use Efficient Compressor Controls

• 75 Hp modulating 60 Hp VSD
• 250 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) 100/290
  34 (38 Input kW)

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Use Efficient Compressor Controls

• 75 HP lubricated screw with modulation control
• A) First shift 250 CFM
• 82.5 Bhp X (.93 factor) X .746kW X .06 X 2200Hrs
  8,738
• .915 Mtr. eff. Hp kWh
• B) Second shift 175 CFM
• 82.5 Bhp X (.865 factor) X .746kW X .06 X
  2200Hrs 8,127
• .915 Mtr. eff. Hp kWh
• C) Third shift 100 CFM
• 82.5 Bhp X (.79 factor) X .746kW X .06 X 2200Hrs
  7,422
• .915 Mtr. eff. Hp kWh
• Total
  24,287

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Use Efficient Compressor Controls
60 Hp Variable Speed compressor A) First
shift 250 CFM 66 Bhp x .746 kW x (.86 factor) x
.06 x 2200Hrs 5,946 .94 ME.
Hp kWh B) Second shift 175 CFM 66 Bhp x
.746 kW x (.61 factor) x .06 x 2200Hrs
4,217 .94 ME Hp kWh C) Third shift 100
CFM 66 Bhp x .746 kW x (.38 factor) x .06 x
2200Hrs 2,627 .94 ME Hp
kWh Total 12,790
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Use Efficient Compressor Controls

• Total Power Savings
• 24,287 - 12,790 11,497 per year
• 60 HP VSD costs 25,000 for a 2.17 year payback!

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• System running with (2)-125 HP OL/OL compressors
• 3.7 kWH/MCF
• Inconsistent efficiency

• System running with (1)-125 HP OL/OL compressors
  and (1)-75 HP VSD
• 3.3 kWH/MCF
• Nearly constant efficiency

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Reduce Compressed Air Usage

• Eliminate inappropriate air users
• Use brushes, blowers, or vacuum systems instead
  of compressed air to clean parts or remove
  debris 
• Use blowers, electric actuators, or hydraulics
  instead of compressed air blasts to move parts
• Use high efficiency nozzles instead of open
  orifices

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Reduce Compressed Air Usage

• Eliminate inappropriate air users
• Use fans to cool electrical cabinets instead of
  compressed air vortex tubes
• Apply a vacuum system 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 packaging

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Reduce Compressed Air Usage

• Minimize unregulated air users
• Install regulators
• Reduced pressure lowers air consumption
• Unregulated users use 47 more compressed air at
  110 vs. 70 PSIG
• Less equipment wear and tear

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Reduce Compressed Air Usage

• Shut off air to equipment that is shutdown or
  abandoned
• Install automatic solenoid valves
• Valve off idled sections of the plant

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Reduce Compressed Air Usage

• Fix Leaks
• Leaks can account for 10-50 of the total
  compressed air usage!
• 1/8 inch dia. hole 25 SCFM 3,000
• 1/4 inch dia. hole 100 SCFM 12,000
• 3/8 inch dia. hole 230 SCFM 26,000
• Based on 8,760 operating hrs/yr _at_ 0.07 per kWh
  energy cost

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Reduce Compressed Air Usage

• 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 program

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Reduce Compressed Air Usage

• Reduce plant system air pressure
• Unregulated air users and air leaks use 28 more
  compressed air at 120 vs. 90 PSIG

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Reduce 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
  compressor
• Install good compressor sequencing controls
• Lower the system air pressure

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Reduce 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 large intermittent air gulpers that
  draw the system down with storage and metering
  valves
• Decentralize compressors

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Receiver 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 minutes every 10
minutes. 200 X 2400 CF required useful free air
to be stored ? P 100-4060 400V X 60/14.7 V
400 X 14.7/60 98 CF 735 gallons 400 CF/8
minutes50 CFM to refill System sees 50 CFM
instead of 200 CFM!
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Lower System Pressure to Lower Air Consumption
95 psig 950 CFM air usage
85 psig 825 CFM air usage
70 psig 700 CFM air usage
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Reduce 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 pressure

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Reduce Compressed Air Usage

• Reduce system air pressure
• Use effective compressor sequencing, storage, and
  compressor controls to regulate system pressure
• Lowers air consumption and compressor pressure
• Most energy efficient

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Sequence Air Compressors
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Typical System Without a Sequencer Cascading
Systems
C1
C2
C3
C4
125 PSIG
125
unload
120
115

• Individual settings
• Large pressure band
• Multiple units at part load
• Very inefficient

110
115
110
105
load
100
100 PSIG
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Sequencers 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 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 sequence

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System Pressure remains consistent as flow rate
varies
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RULE OF THUMB
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Sequencers pay for themselves in energy savings
by reducing pressure band differentials and
lowering air usage

• EXAMPLE- 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
  167,387.00
• .94 (motor Efficiency)
• Reduce Pressure Band by 25 Psig to save
  1220,086.00

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Flow changes but kW does not change proportionally
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Poor efficiency of a cascaded system due to
multiple units at part load
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Sequencers Can Significantly Improve Efficiency
to Minimize Energy Costs

• Total system energy savings of 20-50 are
  expected

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kW/100 CF stays consistent even under varying
loads

• .32 kW/100CF versus .85 kW/100CF (63 Savings!)

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• Switch to LILO Sequencing with a 5 minute
  unloaded time

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Sequencing Significantly Improves Efficiency to
Minimize Energy Costs

• Basis 3 shift operation, .06/kWhr, 20 PSI
  pressure band reduction

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Advanced sequencers provide system flow and
pressure data to manage your 4th Utility

• System 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 consumption

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ManagAIR by Air Technologies System
Report for Ferro 9/7/01 15905 PM Alarm No
Faults Detected Current System Readings-
Pressure108 Flowrate1347
Sequence2,1,3 Previous 8hrs Data Hour1
Hour2 Hour3 Hour4 Hour5 Hour6 Hour7
Hour8 Min Pressure 104 104
104 104 104 104 104 104 Avg
Pressure 108 108 109 109
109 109 109 109 Max Pressure
114 114 114 114 114 114
114 114 Min FlowRate 1274
1274 1311 1322 1324 1349 1311
1305 Avg FlowRate 1448 1468 1648
1647 1739 1870 1644 1718 Max
FlowRate 2274 2298 2504 2485
2545 2629 2409 2432 Min DewPoint
-44 -43 -43 -43 -40
-36 -32 -21 Avg DewPoint -41
-41 -36 -40 -37 -33 -25
-15 Max DewPoint -39 -39 -11
-37 -35 -30 -19
-10 Compressor 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 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
Intercooler 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
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 graph faxed or e-mailed
to you automatically
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Good Maintenance Saves Energy
Inlet Filters
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Good Maintenance Saves Energy
Dirty Coolers
For every 11oF deterioration in the intercooler
approach or increase in water temperature, the
power consumption will increase by 1.
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Good Maintenance Saves Energy
Dirty Coolers

• For every 10oF deterioration of the after cooler
  approach temperature, the dryer load is increased
  by as much as 46.

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Good Maintenance Saves Energy
Dirty Oil Separator

• A dirty oil separator can increase your HP 5

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Energy 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 Efficiency

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Lowering Your Compressed Air Energy Costs

• Trey Donze
• Mike Hotz
• Air Technologies
• 513-539-6747