Compressed Air Systems - NV Energy · without reducing inlet pressure (recip – multi step or pockets) (rotary – turn valve, slide valve, lift valve) Variable Speed •Adjusts

Compressed Air SystemsScott Wetteland, CEM, DNV GL

July 2018

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Smart 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

Free technology

Must participate in 15 community energy events or 75% of all events, whichever is less

At least 75% of devices have to participate to get credit for event

Events are two hours and held 1 p.m.-7 p.m. (typically 3 p.m.-5 p.m.)

South: 1 June – September 30; North: 1 July – September 30

No events the day before or on holidays – 2 event max per week

Facility cannot have an energy management system

Prefer five or more thermostats

Participation requirements

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SolarGenerations

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SolarGenerations incentives

Expected Performance- Performance-BasedBased Buydown Incentive

Up to 25 kW size 25 kw – 500 kW size

Public, Low Income, Non-profit $490 per kilowatt $0.0527 per kWh Residential, Commercial, Industrial $245 per kilowatt $0.0264 per kWh

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SolarGenerations offering

Continuously open

Eligible for system size up to 500 kW

Incentives are paid up front for small systems (EPBB) and over time for larger systems (PBI)

Senior Energy Consultant, CEM, DNV GL

Compressed air and process systems auditor for 20 years

Specialized in design, manufacturing and processing

Performed compressed air energy audits for a diverse group of companies and manufacturers

Performed design/build contracts including performance guarantee

Perform direct installation audits for end users

Instructor Scott Wetteland

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 offerings and incentives

Q & A

Today’s agenda

Fundamentals of Compressed Air

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Compressed air…it’s not rocket science

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Total life cycle costs of an air compressor

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Cut waste, generate results

Consider system and component improvements•With a 10-30% realistic energy savings

Reduce downtime and maintenance costs

Increase production with less rejects

Improve compressed air quality

Improve product quality

Used in 70% of manufacturing facilities

Blowing

Clamping

Conveying

Injection molding

Mixing

Packing

Stamping

Apparel

Automotive

Chemicals

Food

Metal

Plastics

Textiles

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Variety of applications

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

Compressed air definitions

Types of Compressors and Controls

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Types of air compressors

http://www.nrcan.gc.ca/energy/products/reference/14968

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Single acting, reciprocating compressor

http://nuclearpowertraining.tpub.com/h1018v2/css/h1018v2_85.htm

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Double acting, reciprocating compressor

http://nuclearpowertraining.tpub.com/h1018v2/css/h1018v2_85.htm

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Single stage, oil floodedrotary screw compressor

http://www.aircompressorworks.com/blog/index.pHP?mode=post&id=20http://www.gellertco.com/oil-free-nirvana/

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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

http://www.aircompressorworks.com/blog/index.pHP?mode=post&id=20http://www.gellertco.com/oil-free-nirvana/

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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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Three stage centrifugal compressor

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Three stage centrifugal compressor

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Compressor controls types

http://www.nrcan.gc.ca/energy/products/reference/14970

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

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Compressor controls types

http://www.nrcan.gc.ca/energy/products/reference/14970

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 compressor’s 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

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Compressor controls types

VFD

Variable Capacity

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Replacing load/unload compressor with a VSD compressor

Example

Example

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/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 (w/o incentive)33

Replacing load/unload compressor with a VSD compressor

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Typical compressed air system

http://www.nrcan.gc.ca/energy/products/reference/14968

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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Better compressed air system

http://www.nrcan.gc.ca/energy/products/reference/14968

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Best compressed air system

Types of Air Treatment

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

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

Difference between dryers

What type of compressor dominates the compressed air industry in the 40 HP to 500 HP range? Screw compressor

Why are screw compressors 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

Quiz #1

Compressed Air System Management

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 system45

Spotting inefficiencies

To provide cooling, aspirating, agitating, mixing

Blasts to move parts

To clean parts or remove debris

To cool electric cabinets

For personal cooling

Used on abandoned equipment

Inappropriate use of compressed air

Can be significant waste of energy, sometimes

wasting 20-30% of compressor’s output

Cause a drop in system pressure, which can

make air tools function less efficiently,

adversely affecting production

Forces equipment to cycle more frequently

Compressed air leaks

Leaks reduce output

Continuous drain on power

Leakage rate increases exponentially with diameter

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Find, fix air leaks*

*Compressed Air System Leaks Compressed Air System Fact Sheets

Identifying Energy Efficiency Opportunities

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

Replace air tools with electric

* 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 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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Small changes, big savings

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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Switch desiccant to refrigerated dryer

http://www.elliott-scott.com/h000212.htm

Use refrigerated rather than desiccant dryer

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 55

Other measures?

Great energy, cost savings potential

Reduce downtime

Eliminate maintenance crises

Increase competitive advantage

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Benefits

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

Quiz #2

Solutions

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

Identifying opportunities for improvement

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

Air audits

http://www.onsetcomp.com/files/AirCompressorMonitoring-WP.pdf

Simultaneous flow and power measurement

Short and long metering intervals

http://www.onsetcomp.com/files/AirCompressorMonitoring-WP.pdf

Injection molding facility upgraded their existing compressed air system consisting of a 75 HP air compressor to a 75 HP VFD

NV Energy success story 1

Piping was modified as needed

Existing system averaged 47 kW

New system averaged 30 kW

Results:• More than

100,000 kWh savings/year

• $10,000/year in electrical cost savings

• $6,000 NV Energy incentive

Project cost = $45,000

Simple payback = 4 years

ACH Foam upgraded their existing compressed air system consisting of a 20 HP, 50 HP and 75 HP air compressor to a single 125 HP 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 more than 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 payback was 1.2 years

NV Energy success story 2

NV Energy Offerings and Incentives

NV Energy air compressor incentives

<50 HP air compressors are eligible for $45/HP when upgrading to a VFD air

compressor

All incentives capped at 50% of project cost and there are additional cost capping and requirements that must be

met

>50 HP air compressors central control automation,

flow controllers, process upgrades, distribution

upgrades and dryer upgrades are eligible for custom

incentive $0.05 for non-on peak and $0.10 for on peak

kWh savings

The prescriptive incentive and first year savings will

typically cover the incremental cost between a

standard and VFD air compressor purchase price

3-5 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

Rules of thumb

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

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 HP per hour

Rules of thumb

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 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 as long and this can save on your maintenance costs

Rules of thumb

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Questions