Non-Chemical Water Treatment for Cooling...
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Non-Chemical Water Treatment for Cooling Towers www.amec.com Joe Pisano [email protected] AMEC Earth & Environmental, Inc. Tempe, AZ 480-940-2320 E2S2 Conference 2011 New Orleans, LA
Transcript of Non-Chemical Water Treatment for Cooling...
Non-Chemical Water Treatment for Cooling Towers
www.amec.com
AMEC Earth & Environmental, Inc.Tempe, AZ
480-940-2320
E2S2 Conference 2011 New Orleans, LA
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Discussion Topics
Why treat your cooling water?
How does non-chemical water treatment work?
How does it affect energy use, water consumption and maintenance hours?
Findings from Energy Audit at Tinker AFB
Q&A
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Why Treat Your Cooling Water?
No Treatment Results in:
Scale– Impedes Flow– Reduces Heat Transfer– Raises Head Pressure– All increase energy consumption– For a 100 Ton Chiler 1/8” of Scale = 22% more
electricity is required
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Why Treat Your Cooling Water?
No Treatment Results in:
Biological Growth / Biofilm– Reduces Heat Transfer– Biofilm as thin as a hair results in 25% less
heat transfer– Raises Head Pressure– Health Hazard (Legionella)– Corrosion from Acidic Waste Products
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Why Treat Your Cooling Water?
No Treatment Results in:
Corrosion– Bacteria induced– Improper pH Control / CO2 to Carbonic Acid– Reduces Piping and Equipment Service Life
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Why Treat Your Cooling Water?
Traditional Water Treatment is a series of compromises
– Acids are frequently used to control scale
– Oxidizing biocides are used to control microorganisms
– Acids and biocides attack metal
– Corrosion inhibitors must be added to protect the metal pipes and equipment
– Each of these chemicals must be in balance with each other for them to work properly, this requires frequent monitoring and adjustment
– This also means frequent handling of hazardous chemicals by personnel
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How does Non-Chemical Water Treatment Work?
The option of Non-Chemical Water Treatment Specifically pulse powered physical water treatment Potential benefits:
–Safer: No more hazardous chemical handling–Discontinued discharge of chemicals in blow down to sewer–Saves cost of chemicals–Reduces blow down and therefore water use–Blow down could be re-used or redirected because it does not
contain chemicals–Tends to be more forgiving of operational variations–Reduced maintenance–Lower energy use due to better treatment efficiency
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How does Non-Chemical Water Treatment Work?
Principles of Operation:
Two Primary Components– Electromagnetic Field Generator
(Controller)– A Coil-Pipe Assembly (Sized for the
full system flow)
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How does Non-Chemical Water Treatment Work?
Principles of Operation: Electromagnetic field “activates” small-suspended particles in the
water which then act as seeds for precipitation of dissolved minerals.Dissolved mineral such as calcium carbonate (limestone) adhere to
the surface of activated suspended particles rather than pipe or equipment. The particles grow in size until they precipitate out.
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How does Non-Chemical Water Treatment Work?
The precipitate can be easily removed from the system from the cooling tower basin periodically by manual means or by using a Centrifugal Separator (recommended).
Centrifugal Separators are recommended because: –Tower water is exposed to the environment and
therefore is inherently dirty even without the additional precipitate
–They reduces maintenance time required to clean the Cooling System
–They improves water quality and therefore heat transfer efficiency
–They reduce “food” for bacteria and algae–They will, however, increase installation cost
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How does Non-Chemical Water Treatment Work?
Example System Flow Recommended Installation will vary depending on
the application
Self Contained Side StreamBasin Sweeper System
Field Generator
Field Generator
Cooling Tower
Sweeper Piping
Drain
Sepa
rato
r Make-Up
Con
dens
er
Location B
Location APreferred
Diagram Courtesy of Griswold Water Systems
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How does Non-Chemical Water Treatment Work?
But it is not always the right solution: A water test must be done before considering a non-chemical
solution– Will not work with very soft or distilled water– Less effective when the water has a high chloride or silica content – Consult a system supplier before specifying a non-chemical system
Independent testing of the effectiveness for Biological Control is mixed. Recommendation: Design factors need to be considered and biological growth needs to be monitored closely, be prepared to use additional treatment if required.
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Findings from Tinker AFB Energy Audit
AMEC conducted an Energy Audit at Tinker AFB in 2010
One of the energy savings strategies that was considered was non-chemical water treatment for existing cooling tower systems on base.
16 buildings had cooling towers for their central chiller systems with a total of 15,500 installed tower tons of cooling.
Significant potential savings in energy, water use, and maintenance costs were identified.
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Findings from Tinker AFB Energy Audit
Examples of potential savings from implementing non-chemical water treatment on three buildings’ cooling towers systems
BuildingNumber
Installed Cooling
Towers Tons
Estimated System
Installation Cost
Estimated AnnualWater Saving
Estimated Annual EnergySavings
Estimated Annual Chemical andMaintenance
Savings
Simple Payback
Period Years
SIR
1 400 $55,100 $2,800 $8,400 $16,000 2.03 7.48
3902 1600 $174,000 $18,700 $55,600 $56,021 1.34 11.4
3220 800 $110,200 $5,600 $16,800 $32,011 2.03 7.48
Assumptions:1. Electronic water treatment will allow increase in cycles of concentration by 1.0 cycle, this is conservative based on vendor data.2. Chemical Treatment cost/ ton is based on estimated base wide chemical treatment cost / base wide tower tons.3. Chiller power savings is based on decreased condenser heat transfer due to scaling, estimated scaling factor savings used is 10% for central chiller plant units, may likely be more (20%).4. Electrical cost = 0.065/kwh.
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Conclusions
Why Non-Chemical Water Treatment?Can be a solution for existing and new cooling towers and
evaporative condensers Safer than chemical treatmentCan reduce energy consumption in the ROM of 400 kWH/yr/tonCan reduce chemical and maintenance costs in the
ROM of $35 /yr/tonCan reduce water consumption in the ROM of 7 gpd/ton But, it is not the best solution for every application and be sure to
monitor biological growth
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Questions and Answers
Come to our party tonight. 6PM –
buses leave from the Delta Lobby
Or call me at 612-309-6003, or email at
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References
Potential Suppliers: Griswold Water Systems
1597 Industrial DriveNew Smyrna Beach, FL 32168(386) 663-3370http://griswoldwatersystems.com/
Clearwater Systems Corporation – Dolphin WaterCare145 Dennison RoadPO Box 463Essex, CT 06426 US(860) 767-0850http://www.dolphinwatercare.com/Index.aspx
Evapco – Pulse~Pure5151 Allendale DriveTaneytown, MD 21787 USA(410) 756-2600http://www.evapco.com/
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References
Technical References: California Department of Toxic Substances Control Office of Pollution Prevention and Green
Technology, Evaluation of Non-Chemical Treatment Technologies for Cooling Towers at Select California Facilities, February 2009
Cho, Young I., Drexel University, Efficiency of physical water treatments in controlling calcium scale accumulation in recirculating open cooling water system, ASHRAE Research Project 1155-TRP, May 29, 2002
Vidic, Radisav D., University of Pittsburgh, Biological Control in Cooling Water Systems Using Non-Chemical Treatment Devices, ASHRAE Project Number 1361-RP, April 2010
ASHRAE GreenTip #14, Pulse-Powered Chemical-Free Water Treatment
Griswold Water Systems Presentation 2010
