Transcript Compressed Air - Driving Toward Efficiency

Compressed Air
Driving Toward Energy Efficiency
Emerson Process Management
Novaspect. Inc.
June 22 / 23, 2010
Air – Take a System Approach
SRV
Compressor
Drain /
Trap
Air Receiver
Tank
Aftercooler
Separator
Compressor
Drain /
Trap
Filter
Drain /
Trap
Drain /
Trap
Dryer
Filter
User
User
Drain /
Trap
Drain /
Trap
User
PRV
Air Receiver
Tank
User
Separator
User
User
Drain /
Trap
Drain /
Trap
Drain /
Trap
Drain /
Trap
Topics
Taking a Systems Approach
SRV
Compressor
Drain /
Trap
Air Receiver
Tank
Aftercooler
Separator
Compressor Control
Compressor
Drain /
Trap
Filter
Drain /
Trap
Drain /
Trap
Dryer
Filter
User
Heat Recovery
User
Drain /
Trap
Drain /
Trap
User
PRV
Air Receiver
Tank
Condensation Removal
Leaks
Use Concerns
Conditioning Equipment
Receivers
User
Separator
User
User
Drain /
Trap
Drain /
Trap
Drain /
Trap
Drain /
Trap
Take a Systems Approach
• Establish current conditions and operating
Parameters.
- You can’t manage or control what you
don’t measure.
- Identify information “White Space”.
SRV
Compressor
Drain /
Trap
Air Receiver
Tank
Aftercooler
Separator
Compressor
Drain /
Trap
Filter
Drain /
Trap
Drain /
Trap
Dryer
Filter
User
User
Drain /
Trap
Drain /
Trap
User
PRV
Air Receiver
Tank
User
Separator
• Determine present and future needs.
• Look at system design improvement options.
• Prioritize - decide on the most technically and economically sound
options, taking into consideration all of the sub-systems.
• Implement Change(s).
• Revisit operations and energy consumption and analyzing economics
(validate performance).
• Continuing to monitor and optimize the system.
• Continuing to operate and maintain the system for peak
performance.
User
User
Drain /
Trap
Drain /
Trap
Drain /
Trap
Drain /
Trap
Compressed Air Cost
• Compressed air is typically the most expensive utility at a
plant site.
–
–
10 to 15% efficient
A one (1) horsepower air operated motor requires approximately seven
(7) horsepower of electrical energy input to the compressor (100 psig
normal system)
• The compressor uses energy to produce compressed air.
• The compressor produces high pressure and high
temperature air.
• The energy associated with the air temperature is
generally not used.
Compressors - Controls Scheme
Plant
Compressor
Co
Compressor
Co
Compressor Control
•
•
•
•
•
•
•
•
•
•
•
On-off
Suction valve unloading
Clearance pocket unloading
Suction throttling
Bypass to suction
Auto Dual
Load-unload
Variable speed
Variable displacement
Inlet guide vanes
Surge control (venting or blow-off)
Compressors - Controls Scheme
Area 1
Area 2
Area 3
Compressor
Compressor
Compressor
Compressor
Compressor
Compressor
Compressors - Controls Scheme
Area 1
Area 2
Area 3
Compressor
Compressor
Compressor
Compressor
Compressor
Compressor
Compressors - Controls Scheme
Area 1
Area 2
Area 3
Primary
Compressor
L: 98 PSIG
U: 102 PSIG
Compressor 3
L: 102 PSIG
U: 106 PSIG
Compressor 5
L: 106 PSIG
U: 110 PSIG
Compressor 2
L: 100 PSIG
U: 104 PSIG
Compressor 4
L: 104 PSIG
U: 108 PSIG
Compressor 6
Maintenance Cycle
Compressor Intake
• Inlet air temperature affects compressor power
requirements.
• Compressor style dependent, a 10°F decrease in inlet air
temperature can produce a ~2% reduction in power
requirement.
• Inlet air moisture content should be taken into
consideration.
Compressor Waste Heat Recovery
• As much as 80-93% of the electrical energy
used by an industrial air compressor is
converted into heat. In many cases, a properly
designed heat recovery unit can recover
anywhere from 50- 90% of this available
thermal energy.
• Typical uses for recovered heat include
supplemental space heating, industrial
process heating, water heating, makeup air
heating, and boiler makeup water preheating.
• As a rule of thumb, approximately 50,000
Btu/hour of energy is available for each 100
cfm of capacity (at full-load). Air temperatures
of 30 to 40°F above the cooling air inlet
temperature can be obtained.
• Recovery efficiencies of 80-90% are common.


Source: Compressed Air Challenge - Compressed Air Systems Fact Sheet #10
http://www1.eere.energy.gov/industry/bestpractices/compressed_air.html
Traps / Automatic Drains
Air – Liquid
Separator
Timed Trap
-Valve operator with
timed frequency and
duration of opening
Valve is fully open or fully closed, no modulation
Reservoir Trap
Float Trap
-Modulates on varying load
-Mechanical
-Electronic level mechanisms signals
operator to open and close
-Valve is fully open or fully closed, no
modulation
Traps / Automatic Drains
F
D
E
Unbaffled
/ Free
Balance
Space
Baffled /
Pressure
Drop
Across
Space
C
B
D
F
A
D
G
E
C
G
B
D
A
G
G
Compressed Air Leaks
Compressed Air Leak Cost
(0.05 $/kWh electricity and 0.15 $/103scf)
Hole Diameter [inches] Leak Rate [scfm]
Leak Cost [$/yr]
1/64
0.3
20
1/32
1.0
79
1/16
4.0
317
1/8
16.1
1,267
3/16
36.2
2,852
1/4
64.3
5,070
3/8
144.7
11,407
1/2
257.2
20,278
Air Pressure
100
psig
Potential Savings Opportunities
• Open blowing
• Personnel cooling / cleaning
• Cabinet / electronics cooling
• General housekeeping
• Sparging
• Conveyance
• Vacuum generation
Conditioning
• Aftercoolers
–
–
–
Reduce compressed air temperature and remove moisture
Reduce frictional pressure loss
Separators & traps / drains essential
• Air Dryers
–
–
–
–
Ensure moisture free air
Lower dew point
Multiple styles with varying operating costs based on requirements
Regen. control (timed vs. ΔP)
• Filters
–
–
–
Install appropriately sized filters where needed
Efficiencies are available through avoiding pressure drop
Monitor filter pressure drop and apply maintain accordingly
Receivers
• Provide storage to improve compressor operation.
• Provide storage to serve high demand short duration
compressed air needs
–
Compressor operating pressure reduction opportunities
• Serve as moisture separators
–
Refer back to traps / drains slide
• Dampen pulsations
• High pressure storage can be utilized to reduce required
storage volume
Best Practices

Prevent New Leaks - Dry and clean your compressed air.

Reduce Pressure - Run at required pressures, not beyond.

Check Drains - Are your condensate drains stuck open? Are your drain
valves being left open?

Review Piping Infrastructure - Many systems aren't optimized.

Change Filters Systematically - Not every once in a while.

Emphasize Proper Maintenance - Ignoring maintenance costs more.

Stop inappropriate use of compressed air - Cut these to save even
more.

Manage Your Assets - Establish and follow a controls scheme.

Recover Heat - Compressing air generates heat – reuse it!

Fix Existing Leaks - Piping and personnel initiated.
Questions
SRV
Compressor
Drain /
Trap
Air Receiver
Tank
Aftercooler
Separator
Compressor
Drain /
Trap
Filter
Drain /
Trap
Drain /
Trap
Dryer
Filter
User
User
Drain /
Trap
Drain /
Trap
User
PRV
Air Receiver
Tank
User
Separator
User
User
Drain /
Trap
Drain /
Trap
Drain /
Trap
Drain /
Trap