Cooling Tower Lessons

COOLING TOWER STUDY: FACTS & LESSONS LEARNED Washington State Department of Ecology September 2007

Introduction Cooling towers use large quantities of water, and are ubiquitous in industrial and commercial facilities. A standard method of increasing water efficiency in a tower is to re-circulate the water until dissolved solids or biological films begin to coat the internal surfaces of the unit reducing heat transfer. This saves water when compared to simply using single pass cooling water. In single pass flow, water flows one time through the tower and is then discharged to sewer or surface water. The number of times that cooling water can be re-circulated, also termed “cycles of concentration”, can be increased by the use of antiscaling chemicals and biocides or by alternative non-chemical water treatment technologies. In addition to scaling and bio-fouling, corrosion must be controlled when operating metal cooling towers. Corrosion can decrease the lifetime of the equipment. The Technical Resources for Engineering Efficiency (TREE) team is a group of engineers and scientists within the Department of Ecology that provide detailed pollution prevention evaluations to industrial facilities in Washington State. Opportunities for waste reduction are identified. Cost savings for specific recommendations are estimated and provided to the company for their consideration. TREE members have previously encouraged increased water efficiency and conversion from single pass cooling to re-circulation of cooling water without evaluating the chemical use necessary to do so. While most facilities already re-circulate water and have chemical treatment programs, TREE staff identified the need for understanding the tradeoffs between increased water efficiency and increased chemical use. The TREE team conducted this study to better understand the water use, chemical use and the tradeoffs between increased water efficiency and chemical use in cooling towers. A team of four TREE team members focused on operational and environmental impact issues of cooling towers. This report documents the work done and summarizes what was learned. This will improve the quality of the technical assistance the TREE team provides to facilities.

Intent and Approach The study was conducted over a period of one year by Lynn Coleman, Madeline Wall, Tony Cooper and Cristiana Figueroa. The team met, visited sites, searched and reviewed literature, performed calculations, and attended a seminar on a chemical treatment alternative technology. The team used the cooling towers at Crown Beverage Corporation in Olympia as a case study to better understand the tradeoffs between chemical use and water use. Appendix A lists literature resources reviewed. Appendix B provides summaries of site visits and the seminar. Appendix C summarizes the case study.

Lessons Learned Potential application of study findings to TREE Team projects at facilities with cooling towers is summarized below. Lists of questions to ask facility personnel about cooling tower water and chemical use are provided. Also included is a summary of information on non-chemical treatment technologies and practices for cooling tower water.

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Water usage Water conservation from cooling tower operation might be achieved in several ways, each of which may be appropriate in some situations, but not others. 1. Increasing cycles of concentration. A few facilities still use single pass cooling water and are candidates for recirculating systems or air cooled units. TREE should gather information on whether single pass cooling is used and encourage facilities to consider alternatives. Increasing the cycles of concentration above single pass cooling will require careful monitoring of the water quality within the tower and a service contract with an outside vendor is often advised. Facility staff may not have the time or expertise to operate the chemical addition systems in-house. For systems already recirculating water, data should be gathered to determine if the cycles of concentration could be increased. That information includes: what the blowdown set point is, how the set point is determined, what the current cycles of concentration are and who maintains the towers. Measuring flow into and out of the evaporative side of the cooling tower and/or measuring conductivity into and out of the tower could be used to verify cycles of concentration. 2. Use air cooling. Air cooled units are another option. Data could be collected on fluid temperature, air temperatures, and water flow to determine if an air cooled unit is feasible. TREE completed a report, “Air Cooled Fluid Coolers” in January of 2002 which describes those calculations. 3. Improve system maintenance. Cooling towers also require water for maintenance such as replacing water in the tank reservoir and cleaning fill. Some facilities determine the frequency of tank cleaning based on a set time table and some determine it based on water quality considerations. Questions on these operations will determine whether additional water could be saved in these activities. 4. Use variable speed motors. The cooling effect depends on the difference of the wet bulb temperatures of the air going in and the air coming out of the tower. Facilities that have constant heating loads throughout the year may find that during the summer months, they need to operate the towers close to their design capacity. In the winter, due to lower wet bulb temperatures, towers may be operated at reduced water or air flow rates. In western Washington the average seasonal wet bulb range between summer and winter is 20F, and in eastern Washington it is around 30F. A variable frequency drive to control the evaporator fans or water flow is one way of conserving water and energy. Evaporation rates can be optimized for variable cooling load needs or seasonal temperature swings when the operator can control the throughput of air and water. Another option is to have a modular system that allows for shutting down a tower module when not needed. 5. Reuse blowdown. Some industrial facilities may be able to reuse blowdown water for other purposes. High TDS levels and presence of anti-scaling, corrosion inhibition and biocide chemicals should be considered when evaluating potential reuse. In summary, as part of TREE consultation service, answers to the following questions may be useful to evaluate water efficiency: • • • • •

What types of cooling systems are used; closed loop, open loop, evaporative, ammonia chillers? Who maintains cooling towers? Amount of water into cooling towers? Amount of water for blowdown? How are blowdown rate and frequency established? 2

• • • • • • • • •

What is the conductivity set point if one is used to trigger blowdown? How often is the cooling tower reservoir dumped? How is frequency determined? Is a sand filter used to remove sediment? If so, what determines start and stop of backwashing? How much water is used in backwashing? Variability of heating load? Size of cooling towers in tons? Are different cooling towers used to adjust to varying load? Could the heating load be handled by air cooling? Can blowdown be reused within the facility? Is it appropriate to decrease cycles of concentration during the winter months or low heat load periods?

The following data may be useful for TREE to collect relative to water use: • Measure incoming and outgoing conductivity to check cycles of concentration. • Measure incoming and outgoing flows if facility doesn’t have that data. Check for stuck valves. • Visually inspect for leaks or excessive losses from the air inlet and outlet. • Get cost estimate for variable speed drives on cooling tower fans.

Chemical Usage To determine the point at which to add treatment chemicals, facilities use a variety of measurement techniques. The least sophisticated method is to dose X amount of chemical per Y period of time, the period of time being determined most frequently by eyeing the general condition of the water and cooling tower. More advanced methodology includes using a probe to detect conductivity (or some other similar measurement) to indicate whether the water requires treatment and then adding some predefined dosage to bring the probe signal back within the proper reading range. Dosing chemicals on a set volumetric measurement (X amount of chemical per Y gallons of water) is an intermediate methodology employed. A meter able to measure conductivity or some other reliable metric and base a chemical dosage on that variable would be the most desirable. Daily inspection of the metering equipment is recommended to ensure proper operation.

Conventional Cooling Water Treatment Chemicals The characteristics of chemicals commonly used to treat cooling water, including environmental concerns, are described in Tables 1, 2, and 3. The toxicity of specific chemicals was further evaluated in the case study presented in Appendix C.

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Table 1 Characteristics of Common Corrosion and Scale Inhibitors Constituent Function Molybdenates Corrosion Inhibitor

Phosphates

Zinc

Brine

Sulfuric Acid

Hydrazine

Natural polymers (i.e. tannins and lignins)

Pathway of Release Cooling Tower Drift System Blowdown

Corrosion Inhibitor; Scale Inhibitor Corrosion Inhibitor

Cooling Tower Drift System Blowdown

Scale Inhibitor (Regeneration of water softeners) Scale Inhibitor

Softener Backwash

Corrosion Inhibitor (Oxygen scavenger) Dispersant for clay, silt, and metal oxides

Waste water from cooling tower treatment

Cooling Tower Drift System Blowdown

Cooling Tower Drift System Blowdown

Environmental Issue Reports to sludge in POTW and then enters biosphere w/ use of sludge as a fertilizer; Has been demonstrated to livestock health; A voluntary ban is in effect in Boston Promotes the eutrophication of lakes (overgrowth of plant life, e.g., algae) Aquatic toxin; Generally not eliminated by POTW; Priority EPA toxic pollutant Causes severe operational problems at POTW (corrosion) EH&S issue (can cause severe burns), likely dangerous waste stream EH&S issue (carcinogenic), likely dangerous waste stream

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Table 2 Characteristics of Common Oxidizing Biocides Constituent Chlorine (Cl2)

Primary Application Broad spectrum

Chlorine Dioxide

Ozone

Biocide

Bromine (Br2)

Biocide

Notes most common oxidizing biocide, rapidly dissolves in H2O: Cl2+H2OÆH++Cl+HOCl; HOClÆH++OCl-; hypochlorous acid is more effective than hypochlorite ion, thus as pH increases, effectiveness decreases; increases corrosivity of water Gas that dissolves in water; not reactive with ammonia or amines; effective at high pH; very expensive; not stable (rapidly depleted from recirculating cooling water by air-stripping); must be formed on-site

Pathway of Release Cooling Tower Drift System Blowdown Air Emissions

Air Emissions (Smog)

More effective biocide at elevated pH than chlorine; solutions are not as corrosive as chlorine’s;

Environmental Issue Aquatic and human toxin; can cause severe operational problems at POTW; Daughter products of reaction with organics are more toxic than biocide (i.e., chloroform, trihalomethanes, and other carcinogens)

Ground level pollutant; EH&S issue with indoor sump (indoor air quality); unstable (explosive) and must be generated on-site Aquatic and human toxin; can cause severe operational problems at POTW; Daughter products of reaction with organics are more toxic than biocide (i.e., trihalomethanes)

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Table 3 Characteristics of Common Non-Oxidizing Biocides Chemical

Primary Application Biocide

Non-Oxidizing in General (pathway of release is often cooling tower drift system Blowdown) Carbamates Bacteria and fungi Cocodiamine Bacteria Dibromonitrilopropionamide Bacteria (DBNPA) Isothiazolones Broad spectrum Methylene-(bis)thiocyanate (MBT) Quaternary ammonium salts (Quats) Tributyl tin oxide (TBTO)

Effective pH Range 6-9.5

>7.0 6-9.0 6-8.5 6-9.5

Bacteria

6-7.5

Broad spectrum

7-9.5

Fungi and algae

7-9.5

Glutaraldehyde

Broad spectrum

7-9.5

Copper

Biocide/ Algaecide

Silver

Biocide

Comments Aquatic and human toxin; EH&S concern; can cause severe operational problems at POTW Corrosive to copper Cationic charge Quick kill, hydrolyzes rapidly at high pH t1/2 = 3-14 days, dangerous to handle Rapidly decomposes at pH >7.5 Frequently foams, cationic charge, dispersive properties Adsorbs on and protects cooling tower lumber, synergistic with quats – combination broad spectrum Partially inactivated by amines Aquatic toxin; generally not eliminated by POTW; Priority EPA toxic pollutant Aquatic and human toxin; generally not eliminated by POTW

Reducing Chemical Use Cooling tower flow relative to receiving water body flow, chemical concentration and total loading, and type of receiving water body (large sewage treatment plant versus small stream) will determine the value of decreasing cooling tower chemicals. Due to Western Washington’s weather patterns and tendency for high levels of rain during the months of October through March, it may be appropriate to recommend using fewer cycles of concentration during these months, increasing water usage but also decreasing chemical usage. Conversely, it may be appropriate to recommend increasing the cycles of concentration during April through September to decrease water usage, and thus requiring greater chemical treatment. Facility staff and local wastewater treatment system staff should be consulted for appropriateness of this recommendation. Chemical use reduction in cooling towers might be achieved in the following ways: 1. Use more accurate chemical dosing. If chemical doseage is based on time or volume rather than water quality, e.g. conductivity, evaluate the possibility of installing AND maintaining a more accurate method. Cost of chemicals, equipment and availability of qualified staff to operate the system are 6

considerations. This is probably the one opportunity for chemical use reduction in cooling towers for most facilities that TREE works with. 2. Use alternative water treatment technologies. Over the years, several non-chemical water treatment systems have been proposed for cooling tower water treatment. Efficacy ranges from none (“snake oil treatments”) to high. The value of a non-chemical treatment may be different for biological, scaling and corrosion control and will also vary depending on the specific system. Incoming water quality, staff expertise, and other concerns will determine whether a non-chemical treatment is useful. See Table 4 for a list of non-chemical treatments that TREE identified in its research. 3. Use less toxic chemicals. Chemical substitution may be possible in limited situations. Ask who maintains the towers and how they determine appropriate chemical use. Generally, a reputable vendor may have more time and expertise to operate chemical treatment systems than facility maintenance staff. See Table 1, Table 2, and Table 3 for more information on cooling tower chemicals. 4. Use single pass cooling during winter months. Due to Western Washington’s weather patterns and tendency for high levels of rain during the months of October through March, it may be appropriate to recommend using fewer cycles of concentration during these months, increasing water usage but also decreasing chemical usage. Conversely, it may be appropriate to recommend increasing the cycles of concentration during April through September to decrease water usage, and thus requiring greater chemical treatment. Check with facility staff and check wastewater treatment system for appropriateness of this recommendation. Increased hydraulic flow during winter months may or may not be an issue for the wastewater treatment plant and should be a consideration in making decisions about recommending more or less chemical use. As part of the TREE consultation service, the following questions should be asked to evaluate chemical use. • Final discharge location, WWTP or other? • Chemicals used? • How do you decide dose frequency and dosage? • Set point for chemical addition? • Does set point change over time? • Have alternative water treatment technologies been considered? • Is it feasible to use single pass cooling during periods of low heat load?

Alternative Non-Chemical Treatment Technologies Table 4 summarizes the non-chemical treatment technologies and practices for controlling scale, corrosion, and bio-fouling in cooling water identified during the team’s research.

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Table 4 Alternative Technologies for Controlling Corrosion, Scale, and Bacteria/Algae Technology

Corrosion Control

Scale Control

Bacteria/Algae Control

Ultrasound

associated with oxidizing microbioc ides

X

VRTX Chamber (proprietary)

X

X

X

Pulse-Power (e.g., Dolphin System)

X

X

X

Description

When applied to water, ultrasound frequencies >16kHz result in cavitation crating high local pressures and temperatures. Light and highly reactive radicals are emitted. Used as a microbiological control treatment in cooling water systems and more recently as a total replacement technology for conventional chemical water treatment programs. For 1,000 gpm, 24 hours/day operation, 28 kW are consumed. High voltage electricity is used. Heat build up in the transducer; however, heated metal parts are housed within cooling unit and out of contact. Tremendous force created in chamber - molecules collide. Microorganisms are typically incapable of surviving and mineral bonds in water are broken as they pass through the system. Pulse-power system: high frequency pulse generator (controller) and reaction chamber. Controller induces high-frequency, time-varying electromagnetic field into flowing water via a reaction chamber.

Source of

Manufacturer Information Ashland's 6 SONOXIDE® Ultrasonic Water Treatment

VRTX Technologies

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Clearwater

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The technology has been approved by the FDA for the pasteurization of pumpable food fluids. An adaptation of this technology is marketed by Clearwater Technologies in cooling towers.1 It’s hypothesized that the electrical field causes 1

Biological Control in Cooling Towers Treated with Pulsed-Power Systems. Dennis Ophein, PhD and John Lane, Director of Technology, Clearwater Systems. http://www.environmental-expert.com/articles/article1355/article1355.htm 8

Technology

Corrosion Control

Scale Control

Bacteria/Algae Control

Description

Source of

Manufacturer Information

deterioration of cell membranes with consequent death or inhibited function of bacteria and other pathogens. Different types, frequencies and magnitudes of electrical pulses are applied to water recirculating in cooling tower basin and it appears that the effectiveness depends on water chemistry of the feed water; e.g. specific constituents, constituent concentrations, pH, alkalinity. Biological control using pulsed power has been demonstrated in the food industry. Clearwater believes that scaling and corrosion control also occur and is conducting experiments to better understand and document those processes. They hypothesize that the electrical field causes scaling agents to precipitate in the water as powder rather than to adhere to fixed surfaces in the cooling tower. As for corrosion inhibition, steel and copper coupons have been placed several tower basins and measurements are being made over time to evaluate corrosion rates in systems using pulsed power water treatment. Impressed Current

X

X

X

Small cathodic reaction chamber fitted with anode is installed and electrodes positioned within cooling circuit to provide cathodic corrosion protection. Precipitates calcium salts within reaction chamber rather than within heat exchangers of cooling circuit. Microbiological control is achieved by an electrochemical process using electrodes.

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Technology

Corrosion Control

Scale Control

Ultraviolet (UV)

Bacteria/Algae Control

X

Ozone

X

X

Filtration

X

X

Copper ion generator

X

X

X

Mechanical antifouling

X

X

X

Description

The most common UV lamp is the low pressure (LP) mercury type which emits monochromatic light at a wavelength of 254nm and has high germicidal efficiency and is most suited for “good quality “effluents at moderate flow through rates. Medium pressure UV lamps (MP) emit polychromatic light with a more complex spectrum with only some 5% of the wavelength being produced at 254nm, however this is offset by the much higher power output of the medium Pressure lamp with can be up to 7 Kw. Several companies offer ozone treatment apparatus for water cooling towers. The systems compress ambient air, then dry and ionize it to produce ozone. The oxone is added to the circulating water in the tower. Strainers, filters, separators reduce suspended solids to acceptable low level. Often just a portion of the flow passes through the filter (in-line side stream filtration or sump/basin side stream filtration). As a supplement to chemical treatment - lessening the amount of chemical needed. Uses ionic water purification. Also need a device to control TDS and a magnetic water conditioning system and a careful study of water composition. Copper is used as a coagulant to reduce scale and acts as a supplemental bacterial disinfectant (to chlorine in the makeup water) and an algaecide. Devices injected into and retrieved from tubes in cooling system to scour out the tube. "Sidtec rockets." Used in power plants. Designed for use in thermal power plants; may not be applicable to smaller cooling systems

Source of

Manufacturer Information 5

Many, see source of information

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3

Superior I.D. Tube Cleaners (SIDTEC) Inc.

1, 2

10

Technology

Material choices, protective coatings Housekeeping practices Ion Exchange (water softening)

Corrosion Control

X

Scale Control

Bacteria/Algae Control

X X

X

Description

Purchase cooling tower units made of polyethylene or other material that does not corrode or support the growth of algae and bacteria. Eliminate nutrient sources such as oil leaks and process fluid leaks. Based on anodic/cathodic principle - letting a less noble metal (magnesium) be sacrificed (corroded) instead of the system itself. During the process the oxygen in the water will be absorbed, creating H2O and magnesium hydroxide. Literature also claims it kills and prevents growth of bacteria.

Source of

Manufacturer Information 8 UniBasinTM

Elysator, International Water Treatment Maritime AS

See seminar summary in Appendix A

Information Sources 1 U.S. Department of Energy http://www.eere.energy.gov/inventions/pdfs/betzdearborn.pdf#search=%22Sidtec% 20rocket%22 2 David Daniels, Untangling the complexities of cooling water chemistry. http://www.ipecalgary.com/xplatts1.html 3 Charles A. Wilsey, Alternative Water Treatment for Cooling Towers, Ashrae Journal, April 1997. 4 http://www.iic-consultants.com/consultancy/impressed_current.html 5 http://www.iic-consultants.com/consultancy/ultra_violet.html 6 http://www.iic-consultants.com/consultancy/ultrasound.html 7 http://www.vrtx-technologies.com/A_html/pgA1.html 8 http://www.marleyct.com/ 9 http://www.clearwater-dolphin.com/ 10 Ozone Treatment for Cooling Towers, Federal Technology Alert, Reprinted August 1998; originally printed December 1995 .

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Appendix A: Cooling Tower Resources available in X:\Drive TREE Folder Questions and notes from CH20 vendor meeting \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Questions for CH2O.doc

Cooling Tower Operation BAC (Baltimore Aircoil Company), Product and Application Handbook, Volume I – 2005. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\BAC manual.pdf Cooling Towers: Design and Operation Considerations. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Cooling Towers.doc Cooling Water Management, Basic Principles and Technology, Keister, Timothy, ProChemTech International, Inc., 01/05. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Cooling Water Management.pdf Cooling Tower Manual, Cooling Tower Institute: Chapter 1, Cooling Tower Operations (1999) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Cooling Tower Manual Scans\Ch 1 - Cooling Tower Operations.pdf Chapter 2, Introduction to CTI Thermal Design (1998) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Cooling Tower Manual Scans\Ch 2 - CTI Thermal Design.pdf Chapter 3, Cooling Tower Performance Variables (1998) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Cooling Tower Manual Scans\Ch 3 - Cooling Tower Performance Variables.pdf Chapter 6, Water Chemistry and Treatments (1990) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Cooling Tower Manual Scans\Ch 6 - Water Chemistry and Treatments.pdf Chapter 8, Environmental Aspects of Cooling System Operation (1981) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Cooling Tower Manual Scans\Ch 8 - Environmental Aspects of Cooling System Operations.pdf Evaporation Loss from Cooling Towers (a list of methods to calculate evaporation loss; web site addresses provided for reference) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Evaporation Loss from Cooling Towers.doc 12

What’s Up with Cooling Towers, Morrison, Frank T., ASHRAE Journal, July 2004. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\What's up with Cooling Towers.pdf

Best Management Practices Benefits of Clean Water for Cooling Towers, Latzer, Kenneth, ASHAE Journal, September 2002. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Benefits of Clean Water for Cooling Towers.pdf Best Management Practice and Guidance Manual for Cooling Towers, prepared by JEA for the control of pollutants discharged to the sanitary collection system, August 2005.\\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\BMP and Guidance.pdf Cooling System Design for Water and Wastewater Minimization, Kim, Jin-Kuk and Smith, Robin, American Chemical Society, 2004. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Cooling System Design.pdf Cooling Water Best Practices, Environmental Virtual Campus \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Environmental Virtual Campus.htm

Water Conservation Agricultural use of Wastewater Expedites Port of Morrow Plant Startup, Thurman, Greg, Power, Nov/Dec 2001, Vol. 145, Iss. 6, pg. 87. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Agricultural Use of Wastewater.pdf Cooling Tower Water Quality Parameters for Degraded Water, by DiFilippo, Michael N., for California Energy Commission, April 2006. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Cooling Tower WAter Quality Parameters for Degraded Water.pdf Cool Ways to Conserve, Conger, Rand, Plumbing Systems & Design, March/April 2005. ..\Cooling Tower Reference Material\Rand's article.pdf Power plants learn to reuse, recycle, Daniels, David, Power, Sept/October 2001, Vol. 145, Iss. 5, pg. 45. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Powerplants learn to reuse.pdf Use of Degraded Water Sources as Cooling Water in Power Plants, California Energy Commission, October 2003. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Use of Degraded Water Sources as Cooling Water in Power Plants.pdf

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Efficiency Analysis and Performance Optimization of Commercial, Chiller/Cooling Tower Systems, A Thesis Presented to the Academic Faculty, Liu, Hubert H., June 1997. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Thesis on operational parameters.pdf Cooling Tower Fan Control for Energy Efficiency, Stout, Malcolm Russell Jr., 2003. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Energy_Efficiency.pdf Maximizing Cooling Tower Cycles of Concentration, Cunningham, Robert J., Cooling Tower Institute, TP95-08. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\CTI articles\Maximizing Cooling Tower Cycles of Concentration TP95-08.pdf Water Efficiency, Water Management Options, Cooling and Heating, North Carolina Department of Environment and Natural Resources’ Division of Pollution Prevention and Environmental Assistance. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\water management options.pdf

Chemical Treatment 1999 ASHRAE Applications Handbook, Chapter 47: Water Treatment (fundamentals of water treatment and some of the common problems associated with water in heating and air-conditioning equipment) \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Water Treatment.pdf Chemical Treatment for Cooling Water, Mathie, Alton J., Chapter 8 Chemical and Water Usage Should be Optimized. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\ChemicalandWaterSavings.pdf Development of High Cycle Cooling Water Treatment Program, Khambatta, B. S.., Meier, D. A., and Kamrath, M. A., Cooling Tower Institute, TP94-03. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\CTI articles\Development of High Cycle Cooling Water Treatment Program TP94-03.pdf Factsheet: Eliminating Hexavalent Chrome From Cooling Towers, Board of Public Works, HTM Office, City of Los Angeles. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Factsheet Eliminatring Hexavalent Chrome From Cooling Towers.htm Investing in Chemical Cooling Water Treatment, Demadis, Kostas D., Water & Wastewater International, Dec 2005/Jan 2006, 20, 9, pg. 21. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Investing in Chemical Cooling.pdf Making the Best Choices in Water Treatment Additives, Roy Manley, Betzdearborn Inc., Cooling Tower Institute, 1998. 14

\\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\CTI articles\Making the Best Choices in Water Treatment Additives TP98-02.pdf A Performance-Based Approach to Cooling Water Chemistry Control, Fallon, Hugh P., PowerPlant Chemistry, 2004. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\A Performance-Based Approach to Cooling.pdf Risk Management, A Non-Hazardous Biocide for Cooling Water Treatment, Keister, Timothy, EH&S Products, April 2006. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Bromine as biocide.pdf Untangling the Complexities of Cooling Water Chemistry, Daniels, David, Power, September 2002, Vol. 146, Iss. 6, pg. 43. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Untangling the complexities of cooling water chemistry.pdf Water Treatment for Cooling Towers, HPAC Engineering, January 1999. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\HPAC Engineering Water Treatment for Cooling Towers.pdf White Rust: An Industry Update and Guide Paper, Association of Water Technologies, 2002. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\AWT White Rust Corrosion-A Study.htm

Non-Chemical Treatment Alternative Water Treatment for Cooling Towers, Wilsey, Charles A., ASHRAE Journal, April 1997. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\References from HQ library\Alternative Water Treatment for Cooling Towers.pdf ASHRAE Green Top #14: Pulse-Powered Chemical-Free Water Treatment, 2006. Chemical vs. Non-chemical Cooling Water Treatments – a Side-by-Side Comparison, Kitzman, K. A., Maziarz, E. F., Padgett, B., Blumenschein, C. D., and Smith, A. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\IWC_03_22_.pdf Cooling Tower Blowdown, Treatment Using an Inclined Plate Clarifier, Salah, Mohamed Ahmed, Industrial WaterWorld, January/February 2007. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\2007_02 IndustrialWaterWorld CoolingTowerBlowdown.pdf Cooling Towers, Non-Chemical Water Conditioning at Schick, A Pollution Prevention Case study, Connecticut Department of Environmental Protection. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\CT DEP Cooling Towers.htm

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Condenser Water Treatment Using Pulsed Power, Cooling Technology Institute, John Lane, Clearwater Systems and David F. Peck, Hatch Mott MacDonald, presented at the 2003 Cooling Technology Institute Annual Conference, San Antonio, Texas. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\CTI_lane_peck.pdf Dolphin System Water Treatment Study, conducted at MCI, Sacramento Local OPS Facility, by BWI Solutions, Inc., for SMUD Customer Advanced Technologies Program, October 27, 2004. Effective Chemical-Free Microbiological Control for Industrial Cooling Water Systems, Kuchinski, Rusznak, Beardwood, Ashland Specialty Chemical, Cooling Technology Institute, presented at the 2005 Cooling Technology Institute Annual Conference. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\CTI articles\Effective chemical free microbiological control TP05-19.pdf Engineering Case Study 1 for the PowerPure System by Chardon Laboratories.\\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\Case_Study_1_updated.pdf Non-Chemical Water Treatment In Cooling Towers, John Lane/Clearwater Systems, and Gerald Kitner/Engelhard Corporation, Cooling Tower Institute. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\CTI TP00-03 Non-Chemical Treatment.pdf Ozone Treatment for Cooling Towers, Federal Technology Alert, U.S. Department of Energy, New Technology Demonstration Program, December 1995. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\Ozone.pdf Pulse-Power Water Treatment Systems for Cooling Towers, by Bisbee, D., Energy Efficiency & Customer Research & Development, Sacramento Municipal Utility District, November 10, 2003. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\SMUD_PulsePower.pdf The Strategic Envirotechnology Partnership, Green Book Technology Summary Report Utilizing: VRTX Technology, A.W. Chesterton Company, by Grogan, L., Bizzozero, R., and Cain, J., Massachusetts Office of Technical Assistance, December 2001. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\vrtx_green_book_summary_report.pdf Synergistic Application of Chemical and Electromagnetic Water Treatment in Corrosion and Scale Prevention, Colic, Chien, and Morse, R&D Division, ZPM Inc., and Materials Department, UC Santa Barbara, CA, Croatica Chemica Acta, 1998. \\ecylcyfsvrxfile\xprog\TREE\Projects\Cooling Tower Study\Cooling Tower Reference Material\Non chemical treatment\CCA_71_1998_905_916_COLIC.pdf

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Appendix B: Site Visit and Seminar Reports 1. Crown Beverage Corporation March 31, 2006 Site Visit Madeline Wall Tony Cooper Lynn Coleman Cristiana Figueroa Purpose: Learn about the cooling tower operation and processes that depend upon it at the site. We met with Cam McCleary, Plant Engineer, and Bob Powell, Maintenance. Cooling towers maintain two 600-hp air compressors and a vacuum pump operating at optimum conditions. The towers provide cooling water to a closed loop heat exchanger that absorbs the heat from the air compressors and vacuum pump. The make up water flow rate is not measured. Temperatures of water into or out of the cooling towers are not tracked. Thermometer gauges are installed in the closed loop system. The facility has two Baltimore Aircoil Company Model 15146CR cooling towers. The towers have the combined capacity of approximately 300 tons. Two 124 hp pumps provide a combined flow rate of 1200 gpm to the towers. The towers are about 10 years old. In terms of maintenance, the basins are cleaned once per year, and the fans and belt are changed annually. The company CH2O provides maintenance once per month through a service contract, so the company does not know the actual cost of the chemicals used. We obtained the log of the chemicals used. The film media was recently replaced. The Legionelle’s test was conducted to ensure that Legionelle bacteria is not present. Environmental Hygiene Services (Larysa Slobodian, [email protected]) provided the Legionelle’s testing services. Follow-up: • • •

Measure make up water flow rates and temperatures to inform us on water usage and tower efficiency. Meet with Doug Vliet of CH20, who services the towers on a monthly basis, to obtain information about the chemicals used. Calculate chemical useage per volume of water used.

April 19, 2006 and May 16, 2006 Site Visits April 19 - Guy Hoyle-Dodson and Lynn Coleman May 16 - Guy Hoyle-Dodson and Cristiana Figueroa TREE staff measured water flow in and out of the evaporative side of the cooling tower during the timeframe April 19, 2006 to May 16, 2006. Two Fuji Electronics PortaFlow transit meters were installed to measure flow and log totalized volumes. These meters attach to the outside of piping and measure flow 17

by sending an acoustic signal through the pipe and fluid inside the pipe. Total inflow was measured at 244,000 gallons over the period of 27 days. Total discharge was measured at 46,000 gallons. Inflow was typically 20 gpm with spikes to 60 to 70 gpm several times during a 24 hour period. The amount of water evaporated from a tower is typically significantly higher than the bleed off except for towers operating in a single flow mode or at low cycles of concentration. In our case study, 80% of the incoming water to the towers (about 250,000 gallons per month) evaporated or was lost as drift, and 20% was removed as bleed off with the cycles of concentration estimated at 5.3.2 TREE also measured conductivity of inflow and discharge on the evaporative side of the cooling tower using a YSI 63 portable handheld meter. The two grab samples were taken on April 19. The inflow sample was taken at the outside hose bib next to the cooling towers. This was considered the most representative location since no tap in the inflow pipe to the cooling towers exists. Discharge sample was collected from the end of the cooling tower discharge pipe. Inflow conductivity was 140 uS/cm and discharge conductivity was 790 uS/cm. Based on these data, cycles of concentrations would be 790/140= 5.6. TREE staff had questions about this value and did a single point calibration check on the meter. The meter read 103.5 μS/cm when using a 100 μS/cm standard and the meter was deemed to be reading accurately. It was later discovered that the outflow was measured during a time when the sand filter may have been back flushing. Because the sample was not taken during normal blowdown, calculating cycles of concentration is not possible. When TREE takes these measurements in the future, care must be taken to collect samples at the correct place and time. Also, discharge was intermittent and infrequent, making it difficult to take a sample. Table B1 Temperatures of inflow and discharge were taken on May 16, 2006 Temperature Out of Heat Location Temperature In to Heat Exchanger (oF) Exchanger (oF) Evaporative cooling 66.8 73.3 water Closed loop water 80 78 TREE was not able to develop a ratio between chemical use and water use at this facility because the chemical additions varied, were infrequent, and additions did not correspond to the dates that water use data was collected.

2. Twin City Foods, Ellensburg November 16, 2006 Tony Cooper Cristiana Figueroa Madeline Wall Purpose: Learn about evaporative condensers used in an ammonia refrigeration system The seven cooling towers (evaporative condensers) at the facility are part of an ammonia refrigeration system. In the system, ammonia flows in a closed loop from a storage tank, to product freezers, to compressors, through the condensers and back to the storage tanks. The ammonia is liquid in the storage

2

244,000 gallons/46,000 gallons = 5.3

18

tanks, picks up heat in the freezers and leaves as a gas. The compressors and condensers change the gas back to liquid. In the evaporative condensers, city water flows over the pipes that contain ammonia, cooling the ammonia as it passes through. Some water is evaporated during the process. The water recirculates through the condenser while 3 to 5 gallons per minute of cooling water are continuously discharged from each condenser to maintain a chlorine concentration of less than 1%. More discharge is needed during periods of hot weather. The facility uses about 60,000 gallons per day (gpd) of city water in the evaporative condensers. Approximately 7,500 gpd of water is lost to evaporation. A biocide is added to each of the seven condensers to control biological growth. Facility staff place Bio Clor tablets into a holder in the bottom tank portion of each condenser. No other chemicals are used.

3. Dolphin Treatment System at Good Samaritan Hospital, Puyallup December 6, 2006 Lynn Coleman Cristiana Figueroa Madeline Wall The team visited Good Samaritan Hospital to observe the Dolphin Treatment System installed on the facility’s cooling tower. The evaporative cooling tower is a 400 ton Baltimore Air Coil unit. It was installed in 1990, and it cools water for a 200 ton plate and frame heat exchanger (chiller/condenser). The water treatment system had been in place for about four years. Rand Conger, sales engineer with Johnson Barrow Inc and the facility manager, Steve Prideaux, showed us the treatment system and explained how it worked and the results seen at this facility. The facility manger was very happy with the system. Since it was installed, they have not had to use treatment chemicals. They use City of Puyallup well water with variable hardness. Silica levels can be extremely high (up to 60 ppm Si). The results they have experienced after installing the Dolphin system are: • • • • • • • •

Reduced cooling tower water usage by about 14% by increasing their cycles of concentration. (Because sewer rates are 2.75 times the water rates, they focus on water usage from a cost standpoint.) Energy savings of about 11-12%. Cut labor costs. Reduced corrosion and bio-films. More efficient operation of chiller and cooling tower. Less frequent back-flushing required for tower sand filter. Extended equipment life. Consistent colony counts (previously they had large fluctuations)

The Dolphin System is pulse-powered physical water treatment. It uses pulsed, electric fields to control scaling, biological growth, and corrosion. The vendor doesn’t know exactly how it works and didn’t provide any specifics on the mechanisms for controlling scale, biological growth, or corrosion. However, 19

he provided a contact at UW (Guarrin Sakagawa) who was involved in a study evaluating the Dolphin system.

4. WCTI Alternative Technology Site Visit March 16, 2007 Lynn Coleman Lynn, Phil Paschke (Seattle Public Utilities) and Roger Van Gelder (SPU contractor) met with Tom Aeschliman (Wesmar Company – equipment vendor) and Dean Collins (Westin Building facilities manager) to tour a non-chemical cooling tower water treatment system. Lynn came at the invitation of SPU. The Water Conservation Technology International (WCTI) unit is installed at the Westin Building, a 34 story telecommunication facility in Seattle, Washington. The building houses office space and a number of telecommunication servers for the region. The peak summer heating load was estimated by Dean at 1700 to 1800 T. Evaporative losses were estimated at 36,000 gpd. Some basic information about the cooling water technology was provided. Incoming water is treated with a water softener to remove scaling constituents. The unit is run with little to no blowdown which effectively makes the cooling water total dissolved solids (TDS) extremely high. It is essentially brine (concentration of sodium chloride from the water softener). The high TDS keeps bacteria from growing, addressing biological fouling concerns. The vendor did not explain how corrosion issues were addressed given the high salt content. The units at this facility were mostly fiberglass rather than galvanized aluminum. But he stated that other facilities with galvanized units were exhibiting low corrosion rates as measured by coupons kept in the reservoir tanks. Coupons were measured on an occasional basis to track corrosion. Tom also extended the invitation to a seminar that they were giving on April 13, 2007 on alternative cooling water technologies including information on the unit installed at the Westin Building.

5. Technology for Evaporative Cooling Water Treatment and Water Conservation Seminar April 13, 2007 Tony Cooper

Summary of information presented on non-chemical water treatment alternatives: Elysator® by International Water Treatment Maritime AS The Elysator® model line is a treatment option for closed loop water containing systems such as chilling and radiant heating loops. The Elysator® has a large range of product application with flow rates from 2 L per min to 200 L per min. It must be used in a system that can get above 1.5 cycles of concentration. It 20

was initially invented as a maritime product, but has found use in nuclear power plants (Sweden, Norway) and hospitals (St. Peter’s Hospital – Olympia, Children’s Hospital – Seattle). IWTM claims a payback period of 18-24 months. Corrosion of fluid piping is a prime concern for longevity of equipment and must be minimized. Example causes of corrosion include: • High dissolved oxygen content • Low pH levels • High electrical conductivity • Chlorides • Interaction between different metals and alloys The Elysator® attempts to minimize the first three of these through the use of a sacrificial magnesium anode. Through a cathodic/anodic reaction, the magnesium anode is oxidized to form magnesium hydroxide as follows: Mg (s) + 2H2O (l) + ½O2 (aq) ÅÆ Mg(OH)2 (aq) + H2O (l) This reaction accomplishes the first two points simultaneously. First, the dissolved oxygen is reacted and thus removed from solution and prevents the oxidation of the metals that constitute the heat transfer loop. Secondly, the creation of magnesium hydroxide (a strong base) raises the pH of the water in the system to approximately pH 9.5. These two steps also severally limit the ability of aerobic organisms to grow. Finally, the water is now softened and thus limits its ability to conduct electricity, further preventing corrosion. Any iron, copper, or other metal deposits that have formed as a product of corrosion will be collected via a cyclonic-action filter that can be emptied. The anode must be cleaned “as needed” and changed every three to five years. Contact information: Arne Vestad Owner 2607 Bridgeport Way W. Suite 1J University Place, WA 98466 Phone 253.566.1438 Fax 253.566.1512 Mobile 253.279.7680 [email protected] www.iwtna.com

Polymerized Silica/Sodium Chloride Treatment by Water Conservation Technology International, Inc. (Water-CTI) Water-CTI is the licenser for a technology that utilizes polymerized silica and sodium chloride (termed “New Dimension”) softening system to remove scale forming ions, prevent microbial growth, and prevent corrosion. The system is intended to work in large scale, open-loop cooling applications. The system functions at high TDS and high pH to discourage microbial growth. At high TDS, the polymerized silica form s a good corrosion inhibiting layer on piping. The sodium hydroxide and polymeric silica cohabitate 21

to create a colloid. This colloid is critical to the functioning of the system in order to provide excess silica to buffer the system’s silica concentration. Since polymeric silica will not form a colloid with other metalloid salts (i.e., calcium), sodium chloride is used. Mononuclear silica is in makeup water to recharge the polymeric silica/sodium hydroxide colloid. It is important, though, that makeup water is softened through pretreatment. The overall effect is that the silica system will reduce water use due to the high number of cycle of concentrations possible (as high as 300 with corresponding TDS of ~15,000) with an overall goal of (near) zero discharge. Water-CTI has information on their website that provides claims of corrosion levels of only 0.004 mils per year on mild steel. Further study needs to include disposal of brine water waste from (near) zero discharge systems and how a facility’s local POTW is handling the waste stream. Local examples of this technology include Orca Bay Foods (Renton) – had 300 cycles of concentration before reverting to 80 due to the turbid appearance of the water. There is also a high rise in Seattle that is operating at 300 cycles. Contact information: Dan Duke President Water Conservation Technology International, Inc. 31805 Highway 79 South #622 Temecula, CA 92592 Phone (951) 491-9563 [email protected]

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Appendix C: A Case Study of the Crown Beverage Cooling Towers Crown Cork and Seal, a business located in Olympia, WA that manufactures beverage cans from aluminum rolls, uses two single-cell evaporative cooling towers to provide cooling for the facility’s closed cooling water loop. This loop cools machines and tools used in the aluminum can manufacture process, such as air compressors and aluminum cutting machines. This study focused on the evaporative side of the cooling towers. Crown Cork and Seal has two single cell Baltimore Aircoil Model 15146CRs side by side. The 15146CRs have a nominal tonnage of 146 tons and an air throughput of 40,320 cubic feet per minute each. Crown Cork and Seal meters out a measured amount of chemical based on flow rate or totalized flow of water through the cooling system.

Toxicity Analysis Chemicals Used Crown Cork and Seal uses several chemicals to increase the lifespan of their cooling tower: 6324, Unibrom, MXT-1, 6436, and BIOTROL 20. Chemical constituent data was obtained from Material Safety Data Sheets (MSDS) from CH2O’s website, www.ch2o.com. 6324’s active ingredients are phosphonic acid (5 wt%) and sodium hydroxide (5 wt%) which creates a buffered solution to help the cooling tower water resist pH change and prevent scale build up and corrosion. Unibrom, a biocide, contains sodium bromide (10 wt%), sodium hydroxide (5 wt%), and sodium hypochlorite (10 wt%). According to Doug Vliet of CH2O, the chemical treatment vendor for Crown Cork and Seal, bromine is a preferred biocide to chlorine because it is more effective at elevated pH levels than chlorine compounds and the bromine solutions are not as corrosive similar chlorine products. However, chlorine compounds are frequently included in several bromine products (i.e., Unibrom). MXT-1 is a quaternary ammonium compound (10 wt%) based product that is a broad spectrum, nonoxidizing biocide. Biotrol 20 is a biocide used in the cooling towers’ chilled loop. 6436 contains sodium molybdate (10 wt%) and sodium nitrite (10 wt%). The nitrite is an oxygen scavenger and works with the molybdenate to inhibit corrosion. This chemical is used primarily in the boilers.

Toxicity Chemical toxicity was reviewed with an end-of-life focus. Cooling tower blowdown and bleed off primarily end up in large bodies of water such as Puget Sound or the Columbia River and, thus, toxicity was reviewed for fish species. Fathead Minnow, Brook and Rainbow Trout, and Coho Salmon were used to determine toxicity for the above mentioned chemicals. LC50 data was obtained from the RTECS database (http://ccinfoweb.ccohs.ca/rtecs/search.html) and is summarized in Table C1.

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In order to determine what chemicals were causing the largest risk to the environment based on LC50 toxicity, the maximum amount of chemical constituent used was divided by the LC50 to create an adhoc toxicity factor (lbs chemical*L/mg toxicity). The larger the number, the more of a negative environmental impact potential. This data can be seen in Table C2, calculated from the maximum usage amount for each chemical over a twelve month period. From this data, it is possible to determine the relative toxicity of each product based on its usage at Crown Cork and Seal. Table C1 LC50 Data Product Name/Chemical Constituents 6324 Phosphonic acid Sodium hydroxide UNIBROM Sodium bromide Sodium hydroxide Sodium hypochlorite MXT-1 Quaternary ammonium compound 6436 Sodium molybdate Sodium nitrite BIOTROL 20 Tetrakishydroxymethylphosphonium sulfate

CAS #

Wt% LC50fish Duration (mg/L) (h)

Species

13598-36-2 1310-73-2

5% 5%

25

24

Fathead Minnow Brook Trout

7647-15-6 1310-73-2 7681-52-9

10% 5% 10%

0.068 25 0.032

96 24 96

Rainbow Trout Brook Trout Coho Salmon

3152-74-0

10%

0.353

48

Fathead Minnow

7631-95-0 7632-00-0

10% 10%

0.73 0.11

672 96

Rainbow Trout Rainbow Trout

94

96

Rainbow Trout

55566-30-8 20%

Table C2 Toxicity Ranking Compensating for Usage of Water Treatment Chemicals at Crown Cork and Seal Chemical

6324 Phosphonic Acid Sodium hydroxide UNIBROM Sodium bromide Sodium hydroxide Sodium hypochlorite MXT-1 Quaternary Ammonium Compound 6436 Sodium molybdate Sodium nitrite BIOTROL 20 Tetrakishydroxymethylphosphonium sulfate

Toxicity Factor Max Use / LC50 (lbs*L/mg)

Toxicity Rank

NA 0.551

6

82.8 0.113 176

2 7 1

12.1

3

0.686 4.55

5 4

0.0968

8

24

Figure C1 shows the mass of each treatment chemical used per month for a twelve month period. General usage data shows the order of chemical use (in descending order): 6324, Unibrom, MXT-1, BIOTROL 20, and 6436. Figure C1 Water Treatment Chemical Use Diagram Showing Usage of Chemicals from May 2005 to April 2006

Chemical Use (lbs)

Water Treatment Chemical Use 275 250 225 200 175 150 125 100 75 50 25 0 Apr-05

6324 UNIBROM MXT-1 6436 BIOTROL 20

May-05

Jul-05

Sep-05

Oct-05

Dec-05

Feb-06

Mar-06

May-06

Date

Toxicity Analysis Conclusions The relative order of chemical use-toxicity is (in descending order): Unibrom, MXT-1, 6436, 6324, and Biotrol 20. This was an expected result due to the antibiotic properties of sodium hypochlorite, sodium bromide, and quaternary ammonium compounds found in Unibrom and MXT-1. For Crown Cork and Seal, a system that monitors water conductivity and doses the chemicals according to a set algorithm defined by conductivity is recommended.

Water Usage Guy Hoyle-Dodson installed flow meters to measure the flow into and out of the towers at Crown Beverage Corporation. The flow meters obtained data from April 19th through May 16, 2006. During this period of time, the cooling load changed. Only one compressor was operating. Small discharge flows occurred periodically during that timeframe with a total volume of 46,000 gallons discharged from close to 250,000 gallons that went into the system. Eighty percent of the incoming flow was lost to evaporation and drift (200,000 gallons). The amount of water that evaporated seemed high. To ascertain whether the flow measurements were accurate, and the evaporated volume truly that high, an energy-mass balance calculation (from The Cooling Tower Manual (Chp.2, pg 3), Cooling Tower Institute, March 1998) was employed. The energy-mass calculation was based on temperature measurements of the water coming into and out of the tower at the end of the time period as well as the average ambient temperature during that time period. Calculations showed that the design evaporation rate is 1.4%, or 4.95 gpm, of the total volume of water in the system, at the design load. At the current load the evaporation rate was estimated to be 0.43%, or 1.52 gpm. The calculated design evaporation rate was close to the range (1.7-2%) estimated with the “rules of thumb” equations below: 25

Rules Of Thumb for Calculating Evaporation Rate (1) Evaporation Loss from a cooling tower (E) = .001 (Cr) (DT) where Cr = circulation rate in gallons per minute and D T = temperature differential between hot and cold water in °F. The evaporation rate amounts to 1% of the recirculation rate for every 10°F DT. http://www.thermidaire.on.ca/ctcci.html (2) Evaporation Loss = 0.00085 * water flowrate (T1-T2) http://www.cheresources.com/ctowerszz.shtml A Water Conservation Guide for Commercial, Institutional and Industrial Users, New Mexico Office of the State Engineer, July 1999

… the water balance in a cooling tower system can be stated as the relationship between make-up water (M), evaporation (E), bleed-off (B), and draft (D): M=E+B+D Drift is usually so small, if you meter the bleed-off (B) and makeup (M) rates, you can calculate the evaporation rater (E): E = M – B. An approximate guideline states that cooling towers lose 2.4 gallons per minute per 100 tons of cooling. For example, a 700 ton tower loses 16.8 gallons per minute (2.4 gpm/100tons X 700 tons). (Tons: Unit of cooling capacity equal to 12,000 BTUs per hour. Cooling towers in typical facilities range from 50 tons to more than 1,000 tons.) http://www.ose.state.nm.us/water-info/conservation/pdfmanuals/cii-users-guide.pdf

Given that the circulation rate is: 700 gpm*27 days*24hours*60 min= 27.2E6 gallons over the time period we monitored, and utilizing the "rules of thumb" equations, and only one set of temperature (delta T=6.5 with only one compressor running--which happened for only one week of the time period), we get: 1) 176,900 gallons evaporated or 2) 150,400 gallons. The true rate would be higher because the delta T would have been definitely higher for the first three weeks when both compressors operated--Bob Powell (Maintenance staff) commented on this. The energy-mass balance calculations resulted in 116,000 gallons evaporated with only one compressor running the whole time. The evaporation rate needs only be 0.74% (well below the design rate) with both compressors running to reach 200,000 gallon number.

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