Transcript Managing Your Air System-Saving Energy

Lowering Your Compressed Air
Energy Costs
Trey Donze
Mike Hotz
Air Technologies
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
Compressed Air Use in Selected
Manufacturing Industries
Compressed Air Energy Use as a Percentage of Total
Electricity Use
30
25
20
15
10
5
0
Life Cycle Cost of an air compressor

Energy consumption

Installation
Maintenance

Investment

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
Benchmark Your System’s 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
Benchmark Your System’s Efficiency
• Measure your compressed
air requirements
–
–
–
–
Flow
Pressure
Dew point
kW and kWh
• Benchmark your current
system’s efficiency
kWh/MCF
• Receive a detailed report
outlining improvements
KW Meters
time

Typical 24
hrs/day
operation with
low night shift
and high day
shift
consumption.
Steady
weekend
consumption
(leakages).

(64% of installations).
time

Five
days/week
operation,
erratic
demand
fluctuations

(28% of
installations).
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
Performance Comparison
Total KW Input -vs- Capacity
100
90
A
80
B
% Power Input
70
60
C
50
A)
B)
C)
D)
40
D
30
Modulation Control
Active Rotor Length Adj.
Full Load / No Load
VSD
20
10
0
0
10
20
30
40
50
% Capacity
60
70
80
90
100
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 @ 125 PSIG
82.5 Bhp full load power
60HP VSD @ 125 PSIG
66 Bhp full load power
320 CFM
91.5% Motor eff.
290 CFM
94%
Performance Comparison
Total KW Input - vs- Capacity
80.0
75 HP w/ Upper range
modulation control
70.0
Total KW Input
60.0
50.0
40.0
30.0
60 HP VSD
20.0
10.0
0.0
0
50
100
150
200
Capacity (CFM)
250
300
350
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)
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 =
.915 Mtr. eff.
Hp
kWh
$8,738
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 =
.915 Mtr. eff.
Hp
kWh
Total =
$7,422
$24,287
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
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!
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
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
Reduce Compressed Air Usage
Air Pressure
PSIG
50
60
70
80
90
100
110
120
Flow rate
SCFM
58.2
67
76
85
94
103
112
121
• 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
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
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 @ $0.07 per kWh energy cost
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
Reduce Compressed Air Usage
Air Pressure
PSIG
50
60
70
80
90
100
110
120
Flow rate
SCFM
58.2
67
76
85
94
103
112
121
• Reduce plant system
air pressure
• Unregulated air users
and air leaks use 28%
more compressed air
at 120 vs. 90 PSIG
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
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
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 2=400 CF required useful free air to be stored
 P= 100-40=60
400=V X 60/14.7 V= 400 X 14.7/60 = 98 CF = 735 gallons
400 CF/8 minutes=50 CFM to refill
System sees 50 CFM instead of 200 CFM!
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
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
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
Sequence Air Compressors
Typical System Without a Sequencer
Cascading Systems
C1
C2
C3
C4
125
125 PSIG
120 unload
115

110

115
110
100

load

105
100 PSIG
Individual settings
Large pressure band
Multiple units at part load
Very inefficient
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
System Pressure remains consistent as
flow rate varies
RULE OF THUMB
Power consumption
increases 1% for every 2
psi increase in
compressor pressure
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 12%=$20,086.00
Flow changes but kW does not
change proportionally
1800
1600
1400
1200
1000
MEC_SCFM
Total Kw
800
600
400
200
136
126
131
116
121
111
101
106
91
96
81
86
71
76
61
66
51
56
46
36
41
26
31
16
21
6
11
1
0
-0.1
26685.00
25732.00
24779.00
23826.00
22873.00
21920.00
20967.00
20014.00
19061.00
18108.00
17155.00
16202.00
15249.00
14296.00
13343.00
12390.00
11437.00
10484.00
9531.00
8578.00
7625.00
6672.00
5719.00
4766.00
3813.00
2860.00
1907.00
954.00
1.00
Poor efficiency of a cascaded system
due to multiple units at part load
kWh/100CF
1.5
1.3
1.1
0.9
0.7
kWh/100CF
0.5
0.3
0.1
Sequencers Can Significantly Improve
Efficiency to Minimize Energy Costs
Total 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% Savings!)
• Switch to LILO Sequencing
with a 5 minute unloaded time
Sequencing Significantly Improves
Efficiency to Minimize Energy Costs
Total Anual Savings!
$140,000
$122,778
$120,000
$100,000
Tighter Pressure Band
Reduced Unregulated Demand/Leaks
More Efficient Sequencing
Total Estimated Savings!
% Savings
10%
6%
20%
36%
Total
100
$4,235
$2,541
$8,471
$15,347
System Horsepower
200
400
800
$8,471 $16,941 $33,883
$5,082 $10,165 $20,330
$16,941 $33,883 $67,766
$30,695 $61,389 $122,778
$80,000
$61,389
$60,000
$40,000
$30,695
$20,000
$15,347
$0
100
200
400
Total System Horsepower
•
Basis 3 shift operation, $.06/kWhr, 20 PSI pressure band reduction
800
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
ManagAIR® by Air Technologies®
System Report for Ferro
9/7/01 1:59:05 PM
Alarm: No Faults Detected
Current System Readings- Pressure=108
Flowrate=1347
Previous 8hrs Data:
Min Pressure
Avg Pressure
Max Pressure
Sequence=2,1,3
Hour1
104
108
114
Hour2
104
108
114
Hour3
104
109
114
Hour4
104
109
114
Hour5
104
109
114
Hour6
104
109
114
Hour7
104
109
114
Hour8
104
109
114
Min FlowRate
Avg FlowRate
Max FlowRate
1274
1448
2274
1274
1468
2298
1311
1648
2504
1322
1647
2485
1324
1739
2545
1349
1870
2629
1311
1644
2409
1305
1718
2432
Min DewPoint
Avg DewPoint
Max DewPoint
-44
-41
-39
-43
-41
-39
-43
-36
-11
-43
-40
-37
-40
-37
-35
-36
-33
-30
-32
-25
-19
-21
-15
-10
Compressor Data
#1 ZT25 #2 ZT25 #3 ZT25 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
NONE
NONE
NONE
Daily System
Report and graph
faxed or e-mailed
to you
automatically
Good Maintenance Saves Energy
Inlet 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 Energy
Dirty Coolers
For every 11oF deterioration in
the intercooler approach or
increase in water temperature,
the power consumption will
increase by 1%.
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%.
Good Maintenance Saves Energy
Dirty Oil Separator
A dirty oil separator can
increase your HP 5%
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
Lowering Your Compressed Air
Energy Costs
Trey Donze
Mike Hotz
Air Technologies
513-539-6747