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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