Compressed Air Systems February 27, 2018 - Reno, Nevada Instructor: Scott Wetteland Jared Carpenter, DNV GL July, 2016 1
Free Technology 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
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 6 It s not rocket science
7 Total Life Cycle Costs of an Air Compressor
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 8
Variety of Applications Used in 70% of manufacturing Blowing Clamping Conveying Injection molding Mixing Packing Stamping Apparel Automotive Chemicals Food Metal Plastics Textiles 9
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 1 1 http://www.nrcan.gc.ca/energy/products/reference/14968
Single Acting Reciprocating Compressor 1 2 http://nuclearpowertraining.tpub.com/h1018v2/css/h1018v2_85.htm
Double Acting - Reciprocating Compressor 1 3 http://nuclearpowertraining.tpub.com/h1018v2/css/h1018v2_85.htm
Single Stage Oil Flooded Rotary Screw Compressor 1 4 http://www.gellertco.com/oil-free-nirvana/ http://www.aircompressorworks.com/blog/index.php?mode=post&id=20
1 5 Single Stage Oil Flooded Rotary Screw Compressor
1 6 Two Stage Oil Flooded Rotary Screw Compressor
1 7 Two Stage Oil Flooded Rotary Screw Compressor
Two Stage Oil Free Rotary Screw Compressor 1 8 http://www.gellertco.com/oil-free-nirvana/ http://www.aircompressorworks.com/blog/index.php?mode=post&id=20
1 9 Two Stage Oil Free Rotary Screw Compressor
2 0 Single Stage Oil less Rotary Scroll Compressor
2 1 Single Stage Oil less Rotary Scroll Compressor
2 2 3 Stage Centrifugal Compressor
2 3 3 Stage Centrifugal Compressor
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 24 http://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 25 http://www.nrcan.gc.ca/energy/products/reference/14970
Compressor Controls Types VFD Variable Capacity 26
27 Example: Replacing Load/Unload compressor with a VSD Compressor
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) 28
Typical Compressed Air System 2 9 http://www.nrcan.gc.ca/energy/products/reference/14968
Better Compressed Air System Air Intake Air Compressor 1 Aftercooler Zero Air Drain Zero Air Drain End Use Equipment Zero Air Drain Wet Receiver Air Dryer Filter Dry Receiver Pressure Control Air distribution pipes to plant Air Intake Air Compressor 2 Aftercooler Zero Air Drain End Use Equipment 3 0 http://www.nrcan.gc.ca/energy/products/reference/14968
3 1 Best Compressed Air System
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 noncycling 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 38
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 *Compressed Air System Leaks Compressed Air System Fact Sheets 41
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 42
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 A 15-hp electric pump can do the job replacing a 100-hp Air Compressor * Improving Compressed Air Energy Efficiency in Automotive Plants Nasr Alkadi, Kelly Kissock
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. 44
Switch Desiccant to Refrigerated Dryer Air Intake Air Compressor 1 Aftercooler Zero Air Drain Zero Air Drain End Use Equipment Zero Air Drain Wet Receiver Air Dryer Filter Dry Receiver Pressure Control Air distribution pipes to plant Air Intake Air Compressor 2 Aftercooler Zero Air Drain End Use Equipment 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 47
Benefits Great energy, cost savings potential Reduce downtime Eliminate maintenance crises Increase competitive advantage 48
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 pressure Check the system pressure against plant required pressure http://universalmasterproducts.com/products/the-endocube/installation/
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/aircompr essormonitoring-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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