compressed air systems - nv energy · 2020-03-07 · compressed air system consisting of a 75hp air...
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Compressed Air Systems
Jared Carpenter, DNV GLJuly, 2016
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February 27, 2018 - Reno, Nevada Instructor: Scott Wetteland
Free TechnologySmart Networked Thermostats Free equipment and installation
Centralized Management of Heating and Cooling Equipment
Monitor & control from a centralized web portal Typical 10% heating and cooling energy savings Must participate in limited number of Community
Energy Events
Participation Requirements Must participate in 15 community energy events or 75% of all
events, which ever is less
At least 75% of devices have to play to get credit for event
Events are 2-hours and held 1pm -7pm (typically 3pm-5pm)
South – 1 June – September 30
No events the day before or on holidays – 2 event max per week
Facility can’t have a Energy Management System
Prefer 5 or more thermostats
Instructor:Scott Wetteland
Sr. Engineer, CEM DNVGL
Compressed Air & Process Systems Auditor 20 Years
Specializing in Design, Manufacturing & Processing
Performed compressed air energy audits for a diverse group of companies & manufacturers.
Performed Design Build Contracts including Performance Guarantee.
Perform Direct Installation Audits for end users
Todays Agenda:
Fundamentals of Compressed Air
Types of Compressors and Controls
Types of Air Treatment (Dryers and Filtration)
Compressed Air System Management
Identifying Energy Efficiency Opportunities
Solutions
NV Energy Programs and Incentives
Q&A
Compressed Air…
It’s not rocket science…6
Total Life Cycle Costs of an Air Compressor
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Cut Waste, Generate Results
Consider system and component improvementsWith a 10-30% realistic energy savings
Reduce downtime and maintenance costs Increase production with less rejects Improve compressed air quality Improve product quality
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Variety of Applications
Used in 70% of manufacturing
Blowing
Clamping
Conveying
Injection molding
Mixing
Packing
Stamping
ApparelAutomotiveChemicalsFoodMetal
PlasticsTextiles
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Compressed Air Definitions SCFM = Standard Cubic Feet per Minute -
Defined mass air flow rate. ACFM = Actual Cubic Feet per Minute – the
actual volumetric air flow. Inlet Pressure = The actual pressure at the
inlet flange of the compressor. PSIA = Pounds per Square Inch Absolute. PSIG= Pounds Per Square Inch Gauge. Pressure Dew Point = For a given pressure, the
temperature at which water will begin to condense out of air.
Types of Air Compressors
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http://www.nrcan.gc.ca/energy/products/reference/14968
Single Acting –Reciprocating Compressor
12 http://nuclearpowertraining.tpub.com/h1018v2/css/h1018v2_85.htm
Double Acting -Reciprocating Compressor
13 http://nuclearpowertraining.tpub.com/h1018v2/css/h1018v2_85.htm
Single Stage – Oil FloodedRotary Screw Compressor
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http://www.aircompressorworks.com/blog/index.php?mode=post&id=20http://www.gellertco.com/oil-free-nirvana/
Single Stage – Oil FloodedRotary Screw Compressor
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Two Stage – Oil FloodedRotary Screw Compressor
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Two Stage – Oil FloodedRotary Screw Compressor
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Two Stage – Oil FreeRotary Screw Compressor
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http://www.aircompressorworks.com/blog/index.php?mode=post&id=20http://www.gellertco.com/oil-free-nirvana/
Two Stage – Oil FreeRotary Screw Compressor
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Single Stage – Oil lessRotary Scroll Compressor
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Single Stage – Oil lessRotary Scroll Compressor
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3 Stage Centrifugal Compressor
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3 Stage Centrifugal Compressor
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Compressor Controls Types Start/Stop
Turns the motor driving the compressor on or off in response to a pressure signal
Load/Unload Allows the motor to run continuously, but unloads
the compressor when a predetermined pressure is reached
Modulation Restricts inlet air to the compressor which reduces
compressor output
24http://www.nrcan.gc.ca/energy/products/reference/14970
Compressor Controls Types Dual/Auto Dual
Allows selection of either start/stop or Load/Unload. On rotary screw compressors will stop compressor after running unloaded for a set time
Variable Displacement Allows progressive reduction of the compressors displacement
without reducing inlet pressure. (recip – multi step or pockets) (rotary – turn valve, slide valve, lift valve)
Variable Speed Adjusts the compressor capacity by varying the speed of the
electric motor
25http://www.nrcan.gc.ca/energy/products/reference/14970
Compressor Controls Types
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VFD
Variable Capacity
Example: Replacing Load/Unload compressor with a VSD Compressor
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Example: Replacing Load/Unload compressor with a VSD Compressor
A 100 hp L/UL compressor rated at 75 kW and unloaded power 20 kW
On an average the compressed air demand is 60% of its full load capacity
Annual operating hours 5,000 h/yr(4,000 hrs loaded and 1000 hrs unloaded)
EC L/UL = (75 x 4,000)+(20 x 1,000)= 375,000 kWh/yr
EC VSD = 75 x 0.50 x 5000 = 187,500 kWh/yr
Annual ES = 375,000-187,500 = 187,500 kWh/yr
Project Cost ~ $40,000
Incentive = 187,500 x 0.10 = $18,750.00
Simple Payback= 2.13 yrs (WO Incentive)
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Typical Compressed Air System
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http://www.nrcan.gc.ca/energy/products/reference/14968
Better Compressed Air System
Air Compressor 1
Air Compressor 2
Air Intake
Air Intake Aftercooler
Zero Air Drain
Aftercooler
Zero Air Drain
Wet Receiver
Air Dryer
Dry Receiver
Filter
Pressure Control Air
distribution pipes to
plant
End Use Equipment
End Use Equipment
Zero Air Drain
Zero Air Drain
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http://www.nrcan.gc.ca/energy/products/reference/14968
Best Compressed Air System
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Desiccant Regenerative Dryers
http://www.goscorcompressedair.co.za/product/desiccant-dryers/
Non-Cyclic Refrigerated Dryer
Cyclic Refrigerated Dryer
http://www.airbestpractices.com/technology/air-treatment/n2/types-compressed-air-dryers-refrigerant-and-regenerative-desiccant
Difference between dryers Refrigerated dryers reduce the temperature of
compressed air through contact with a cold medium
Since cold air cannot hold as much moisture as hot air, saturated air condenses out moisture as the air temperature decreases, drying the air
The resultant moisture is removed using a moisture separator within the dryer and eliminated from the dryer through the drain system
Once a non-cycling dryer is powered on, the refrigeration system runs continuously regardless of demand. Most non-cycling dryers include a hot gas bypass valve to keep the dryer from freezing.
Difference between dryers A cycling dryer can store cold energy within the unit
until it is needed, which offers the ability to use energy in proportion to the demand. Most non-cycling dryers include a hot gas bypass valve to keep the dryer from freezing.
Desiccant dryers use porous desiccant beads to adsorb moisture from untreated air. They don’t rely on a refrigeration system to cool the air.
Desiccant dryers can use up to 30% of the compressed air to remove moisture.
Non-cycling dryers just keep running.
Cycling dryers cost the most but save the most energy and remove the most moisture.
Quiz# 1
What is type of compressor dominates the compressed air industry in the 40-hp to 500-hp range?
Screw Compressor
Why screw compressors are so common?
Low purchase and operating cost
What is the maintenance over time?
Oil changes, filters, oil separators, compressor rebuild, etc.
What is the most efficient dryer?
Cyclic refrigerant dryer
Spotting Inefficiencies
Inappropriate use of compressed air
Incorrect compressor type based on the application
Compressed air leaks
Operating compressors at higher pressure
Inappropriate part-load control
Inefficient air dryer system
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Inappropriate Use of Compressed Air
Compressed air to provide cooling, aspirating, agitating, mixing
Compressed air blasts to move parts
Compressed air to clean parts or remove debris
Compressed air to cool electric cabinets
Compressed air for personal cooling
Compressed air used on abandoned equipment
Compressed Air Leaks
Leaks can be a significant waste of energy, sometimes wasting 20-30% of a compressor’s output
Leaks cause a drop in system pressure, which can make air tools function less efficiently, adversely affecting production
Forcing the equipment to cycle more frequently
Find, Fix Air Leaks*
Leaks reduce output
Continuous drain on power
Leakage rate increases exponentially with diameter
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*Compressed Air System Leaks Compressed Air System Fact Sheets
Replace Air Tools with Electric
Air power motors use 25 cfm/hp, 7 times more electricity than electric motor
Higher maintenance cost increases with air motor
Impact on air driven tools due to moisture
Choose high-efficiency electric motor
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Replace Air Tools with Electric Air motors use 7 x more electricity than
electrical motors*
Example:
Replace 100 x 1-hp air pumps with electric pumps
Cost savings = 100 hp/0.9x6/7x0.75 kW/hp x 6,000 hr/yr x$0.10/kWh =$43,000/yr
* Improving Compressed Air Energy Efficiency in Automotive Plants Nasr Alkadi, Kelly Kissock
A 15-hp electric pump can do the job replacing a 100-hp Air Compressor
Small Changes, Big Savings
Small reduction in pressure has a big impact on efficiency
1% reduction in power per 2 psi pressure reduction
Example: Reducing pressure setting from 110 psig to 100 psig on fully loaded compressor operating 6,000 hr/yr saves $2,600 a year.
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Switch Desiccant to Refrigerated Dryer
Air Compressor 1
Air Compressor 2
Air Intake
Air Intake Aftercooler
Zero Air Drain
Aftercooler
Zero Air Drain
Wet Receiver
Air Dryer
Dry Receiver
Filter
Pressure Control Air
distribution pipes to
plant
End Use Equipment
End Use Equipment
Zero Air Drain
Zero Air Drain
45 http://www.elliott-scott.com/h000212.htm
Other measures? Smart air compressor controls
Savings varies from 20-60%
Re-use waste heat generated by the compressor in a suitable application
Space heating
Pre-heating boiler feed water
Pre-heating process water
Water heating in laundries
Use storage tank of 4-5 gal/CFM when coupled with a load/no-load compressor
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Benefits
Great energy, cost savings potential
Reduce downtime Eliminate
maintenance crises
Increase competitive advantage
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Quiz#2
What parameters change when air is compressed?
Pressure and Temperature Which of the compressors is used to supply large
quantities of air for a medium to high pressure range?
Centrifugal
Identifying Opportunities for Improvement
Review your compressor control strategies
Check the dryer capacity
Check compressor system’s operating schedule
Check pressure at unit vs. on the floor
Air leakage
Moisture issues
CFM versus kWh
Check the system pressure against plant required pressure
http://universalmasterproducts.com/products/the-endocube/installation/
Check pressure
Performing Air Audits Reviewing Compressed Air End Use in the Plant
Simultaneous Flow and Power Measurement
http://www.onsetcomp.com/files/AirCompressorMonitoring-WP.pdf
Short and Long Metering Intervals
http://www.onsetcomp.com/files/AirCompressorMonitoring-WP.pdf
NV Energy Success Story 1
Injection Molding Facility upgraded their existing compressed air system consisting of a 75HP air compressor to a 75HP VFD.
The existing piping was modified as needed.
The existing system averaged 47 kW and the new system averaged 30 kW.
The retrofit resulted in over 100,000 kWh savings per year, $10,000 per year in electrical cost savings and an NV Energy incentive of $6,000.
With a project cost of $45,000, the simple pay back was 4 years.
NV Energy Success Story 2 ACH Foam upgraded their existing compressed air system
consisting of a 20HP, 50HP and 75HP air compressor to a single 125HP VFD.
The existing piping and flow control valve were also replaced and modified.
NV Energy Success Story 2 The existing system averaged 93 kW and the new system
averaged 32 kW.
The retrofit resulted in over 500,000 kWh savings per year, $40,000 per year in electrical cost savings and an NV Energy incentive of $30,000.
With a project cost of $80,000, the simple pay back was 1.2 years.
NV Energy Air Compressor Incentives
50HP and smaller air compressors are eligible for $45 per horse power when up grading to a VFD air compressor.
Above 50HP air compressors are eligible for the custom incentive of $0.05 for non on peak and $0.10 for on peak kWh savings. Pre and post data is required to validate the savings.
Central Control Automation, Flow Controllers, Process Upgrades, Distribution Upgrades and Dryer Upgrades are eligible for the custom incentive of $0.05 for non on peak and $0.10 for on peak kWh savings. Pre and post data is required to validate the savings.
All incentives are capped at 50% of the project cost and there are additional cost capping and requirements that must be met.
The prescriptive incentive and first year savings will typically cover the incremental cost between a standard and VFD air compressor purchase price.
Rules of Thumb
3 to 5 gallons of storage for each actual CFM or 15 to 25 gallons per compressor HP.
For industrial applications (100 PSIG) ~4 to 4.5 CFM per HP. The more CFM per HP the less energy used.
Air Receiver Size (The more air storage the less energy used)• Modulating Control = 1 gallon per CFM (very inefficient)• On-Line/Off-Line = 3 to 5 gallons per CFM• Stop-Start/ Variable Speed = 2 to 5 gallons per CFM.
Air Piping Size by CFM and Pressure Drop (The less pressure drop, the less energy used):• Compressor Room Header---0.25 PSIG pressure drop per 100 feet of piping.• Main Line = 0.1 PSIG pressure drop per 100 feet of piping.• Loop Line = 0.1 PSIG pressure drop per 100 feet of piping.• Branch Line = 0.5 PSIG pressure drop per 100 feet of piping.
Rules of Thumb Lowering Compressor Pressure settings 2 PSIG will result
in a 1% energy savings. Lowering Compressor Inlet Air Temperature 10° F will
result in a 2% energy savings. The average energy cost to operate an air compressor is
approximately $0.10 per horse power per hour. Compressed Air system leaks totaling the size of a 1/4"
orifice, at 100 PSIG, running 24 hours a day will waste approximately $15,000 worth of electrical energy a year.
Using Synthetic Compressor Lubricants can save you up to 9% of the energy cost of operating your compressor as compared to using a non-synthetic lubricant.
Size Compressed Air Line Filters to be twice (2x) your compressor CFM flow rate.• This will lower your pressure drop 2-3 PSIG and save an additional 1% on electrical energy costs.• Elements will last twice (2x) as long and this can save on your maintenance costs.
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