### MEMORANDUM

Tetra Tech, Inc. 10306 Eaton Place, Suite 340 Fairfax, VA 22030 phone 703 -385 - 6000 fax 703 -385 - 6007 TO : Paul Shriner and Jan Matuszko, EPA FROM : John Sunda (SAIC) and Kelly Meadows DATE: March 25, 2010 SUBJECT: Water Balance , Flow Reduction, and Optimization of Recirculating Wet Cooling

Towers Introduction Tetra Tech and SAIC were tasked with developing documentation to support regulatory options that may require a facility

to retrofit to closed
- cycle cooling. This memo discuss es the reduction in flow that can be expected, ways to optimize those reductions, and estimated the additional costs that will be incurred to optimize the cooling towers. Estimation of Flow Components in Recirculating Wet Cooling Towers Closed
- cycle cool ing s ys tems significantl y reduce the volume of cooling water withdrawals. However, there is still a need for some water to be withdrawn; make
-up water replaces losses to the system. The water balance in and out of a recirculating wet cooling tower is def ined by the following equation : Make
-up = Evaporation + Drift + Blowdown The make
-up flow volume is ty picall y controlled by water level monitors in the cooling tower basins which control the make
-up water pumps to ensure that a sufficient depth of water is maintained in the cooling tower basin to allow for proper operation. As such, the volume of the make
-up withdrawals is driven by the volume of the three components of water exiting the recirculating water s ys tem ( i.e., the right hand side of the above equation) . Each of these is discussed in detail below
.- 2
-

Evaporation The amount of evaporation is driven by the amount of heat that is transferred to the cooling water in the exhaust steam conden s ers. The amount of this heat is a function of the power generation rate and the efficiency of the boiler and the generating system. In a ty pical coal
- fired steam boiler , 7 5 % to 90% of the heat energy derived from the fuel is converted to steam energy (Dbal et al 1995) . The component of th e steam energy that is not converted to electricity in the turbines will exit the system through the cooling water s ys tem. The h eat exiting through the cooling water s ys tem is transported to the towers through an increase in the temperature of the cooling water passing through the steam condenser. For any given power plant output level , the circulating cooling water flow rate will determine the temperature difference between the condenser inlet and outlet
. At the cooling tower end of this system, the heat that exits the system leaves through a combination of evaporation of water and an increase in the sensible temperature of the air passing through the s ys tem. In conventional wet cooling towers, the majority of the heat exits the system through evaporation. The evaporation rate can be estimated using the following equation: Evaporation (gpm) = Recirculation (gpm) x ∆T (  F) x Evap oration Factor Table 1 below shows evaporation factors provided by two technical sources plus the value that is equivalent to a tower where 100% of the heat exits the tower via evaporation. While 100% evaporation is possible , it would only occur when the ambient air has low humidity and is as warm ( or warmer) than the hot water entering the tower. The mechanical draft cooling towers engineering evaporation estimation factors shown in Table 1 are equivalent to conditions where roughl y 80% of the heat exiting is via evaporation . The actual proportion of heat exiting the tower through evaporation at any given time will vary depending on tower design, the amount of air flow, the water temperature and meteorological conditions such as wet bulb temperature and dry bulb temperature
. Differences in these factors will affect the evaporation rate ( and thus the make
-up volume ) by

only a modest amount however , s ince conventional towers are designed such that most of the heat exits via evaporation . Non
- conventional designs such as hy brid plume abatement towers will have a lower proportion of heat exiting through evaporation and thus a low er make
-up water volume
. Table 1 Wet Cooling Tower Evaporation Factors Source Evaporation Factor Percent of Total He at

Exiting Tower As Evaporation Marley 0.0008 78% NPCI 0.00085 82% 100% Evaporation 0.00103 100%- 3
-

Drift Drift (aka windage) is the small proportion of the recirculating cooling water that leaves the tower as fine droplets entrained in the exiting air flow. Drift is ty pically estimated as a percentage of circulating water flow and will vary with tower design. Drift is different from evaporation in that it is not responsible for removing heat from the s ys tem, but can be responsible for removing some o f the dissolved solids that build up in the recirculating cooling water that otherwise would exit through the blowdown. A change in the drift rate at a tower maintained at a specific cycle of concentration (see below) will affect the blowdown volume but not the make
-up water volume. Table 2 below presents drift estimation rates for different ty pes of cooling tower designs without drift eliminators and for those with drift eliminators
. 1 Table 2 Cooling Tower Drift Factors Tower Type Drift Estimation Fa ctor* Natural Draft 0.3 to 1 .0 % Mechanical Draft 0.1 to 0. 3 % Mechanical Draft Tower with Drift Eliminator 0. 0 05 % Mechanical Draft Tower with High Efficiency

Drift Eliminator 0. 00 05 % * Drift (gpm) = Recirculation (gpm) X Factor Source (Engineering Tips 2009) Blowdown Of the three components that comprise the make
-up water volume requirements, blowdown is the one component that is completely under the control of the cooling tower operator. The blowdown is the component us ed to control/prevent the buil d
-up in the dissolved and suspended solids in the recirculating water. The oretically , it can range from 0 % to 100% of the condenser cooling water flow (minus drift and evaporation)
. The latter condition (i.e., 100%) describes a cooling tower operating in the helper mode with no recirculation. Since nearl y all make
-up water sources will contain some dissolved solids, a tower operating with 0 % blowdown woul d experience a continuous build
-up of dissolved solids in the recirculating water as dissolved soli ds are left behind by the evaporating make
-up water. This build
-up would increas e until the concentration becomes so high that the amount of solids lost in the drift equals the amount coming in through the make
-up water. Usually before that happens, the build
-up of dissolved solids in the system will reach saturation concentration s for certain components , resulting in the precipitation of solids as scale, suspended solids , and sludge
. These solids can create an array of operational problems including the plugging of piping and tower media, a reduction in the efficiency of heat exchange surfaces, and an increase in metal corrosion
1 Note that engineering costs for the revised Phase II rule included drift eliminators for all cooling tower installations.- 4
-

due to anaerobic conditions beneath the deposited l ayer of solids
. Corrosion may also increase due to higher salt content of the water
. There are no upper limits for the blowdown volume , and some s ys tems may operate at relativel y high blowdown rates in order to completel y avoid di ssolved solids
- related problems or to increase turbine efficiency by providing supplemental cooling b y operating the system in essentially

a partial once
- through mode. 2 This provides cooler water to the condensers whenever the source water temperature is below the tower effluent temperature , which is most often the case. For any given make
-up water quality and tower system design , cooling tower manufacturers and treatment chemical vendors can evaluate what should be the acceptable upper operating limit for the concentration of the mix of dissolved solids present. The acceptable upper limit is not fix ed and can be adjusted upward through the use of treatment chemicals. Rather than defining such upper limits in the form of a maximum c oncentration , this limit is often expressed as a multiple of the make
-up water concentration. The ratio of the dissolve d solids concentration of the more concentrated recirculating water to the dissolved solids concentration of the make
-up water is called the cycle of concentration (COC)
. The recommended maximum cycle of concentration is directly related to the quality of the make
up water and can be modified by use of water treatment chemicals . A make
-up water source with high dissolved solids (e.g., saltwater) or high hardness will tend to result in the need to operate at a lower COC , even with the use of treatment ch emicals
. Towers that operate at a COC near the upper operating limit have a greater potential for increased operating and maintenance costs due to higher chemical costs or increased equipment maintenance costs due to the higher potential for corrosion and s cale buildup. In general, cooling tower treatment chemical vendors will evaluate the water chemistry and associated costs for various COC levels and will select an optimal operating COC and treatment chemical dosage. As the COC is increased , there wi ll be an increase in chemical dosage and at the same time a decrease in the amount of chemicals lost in the blowdown. This optimal COC will usually

involve financial and operating considerations that strike a balance between the variations in treatment ch emical dosage and cost, the limits of the ability of treatment chemicals to prevent problems associated with scale formation, corrosion and biofouling , and the benefits of using less water . In cases where there are significant costs associated with obtaining source water and disposing of blowdown, these costs may provide additional incentive to set the optimal COC to higher values and thus reduced make
-up water volumes
. A cooling tower treatment chemical vendor 3 indicated that most power plants practice minimal treatment chemical use , often operating well below the optimal COC , primarily because of the relatively low cost of obtaining make
-up water and disposal of blowdown. A general rule of thumb for most towers is that calcium hardness in the recirculating water should be limited to 350 to 450 ppm unless treatment chemicals are used. Other limiting factors ,
2 In other words, a facility could only recirculate a portion of the heated circulating water through a cooling tower and back to the condenser; the remaining portion would be discharged as if it were once
- through cooling water. 3 Keister, Timothy. ProChemT ech International Inc.- 5
-

such as silica, phosphate , and process contaminants should be considered as well (Harfst , 2008). Saltwater can be concentrated to about 55,000 ppm TDS in cooling towers with no serious scaling problems without pH adjustment (Nelson, 1986). The ratio of this 55,000 ppm to a ty pical seawater concentration of 35,000 ppm results in a calculated COC of 1.57 , and so a COC for full strength seawater of 1.5 is a reasonable value to use for s ys tems requiring minimal use of treatment chemicals. Estuarine and tidal waterbodies that contain some combination of saltwater and freshwater or brackish water will be able to operate at somewhat higher COC values. The recommended COC values for saltwater s ys tems range from 1.5 to 2.0
. In general, the higher the COC, the greater the reduction in make
-up withdrawals, as less water is blown down. Appendix A shows cooling tower flow balance components for a 100,000 gpm c ooling tower for cycles of concentration ranging from 1.1 to 10.0 and for t emperature rise s across the condenser (∆ T) ranging from 10 to 30  F
. The percent flow reduction values represent the intake water flow reduction that would occur if this recirculating s ys tem replaced a once
through cooling s ys tem with the same condenser cooling water flow rate. Table 3 below shows the percent flow reduction values for the different values of COC and ∆ T based on the data in Appendix A. Table 3

10 15 20 25 30 1. 1 90. 7% 86. 0% 81. 3% 76. 6% 72. 0% 1. 2 94. 9% 92. 4% 89. 8% 87. 3% 84. 7% 1. 5 97. 5% 96. 2% 94. 9% 93. 6% 92. 4% 2. 0 98. 3% 97. 5% 96. 6% 95. 8% 94. 9% 3. 0 98. 7% 98. 1% 97. 5% 96. 8% 96. 2% 4. 0 98. 9% 98. 3% 97. 7% 97. 2% 96. 6% 5. 0 98. 9% 98. 4% 97. 9% 97. 3% 96. 8% 6. 0 99. 0% 98. 5% 98. 0% 97. 5% 96. 9% 8. 0 99. 0% 98. 5% 98. 1% 97. 6% 97. 1% 10.0 99. 1% 98. 6% 98. 1% 97. 6% 97. 2% Evap or at io n Rat e = T x gp m x 0. 00085 (82% o f he at los s is e va por at ion) Dr ift Ra te = gpm x 0. 0005/100 (hig h e fficie ncy drift e lim ina tor s) Delta T( o F) Cy cl es of Conce nt ra ti on Ca lc ul atedPe rcent Flo w R ed ucti on

Figure 1 presents a graph of the data in Table 3 for ∆ T = 10, 20, and 30  F. This data shows that the change in percent reduction in make
-up water volume diminishes rapidly as the COC exceeds a value of about 5.0 and becomes nearl y as ymptotic at a value of 10.0. The COC and ∆ T are primary factors driving the percent flow reduction of retrofit coo l ing towers.Figure 1 Cooling Tower Percent Flow Reduction for Various Delta T and COC Values

70.0% 75.0% 80.0% 85.0% 90.0% 95.0% 100.0%

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 COC (1.1, 1.2, 1.5, 2, 3, 4, 5, 6, 8, 10)Percent Flow Reduction
Delta T = 10 F Delta T = 20 F Delta T = 30 FChemical Requir ements Costs of Operating at Higher Cycles of Concentration

A major component of cooling tower and cooling system maintenance involves measures taken to control biological growth, corrosion, and the build
-up of deposits on metal surfaces and tower media. These deposits can consist of biological growth, solids contained in the make
-up water, solids cleaned from the air, and solids that precipitate out of solution. The most damaging metal corrosion is the result of localized pitting which occurs under surf ace deposits. Additionally, deposits on heat transfer surfaces result in a reduction of overall s ys tem power generating efficiency and the growth of certain microorganisms such as Legionella can create a human health hazard. Control of suspended solids in recirculating cooling water s ys tems can include pretreatment of make
-up water as well as side
- stream filtration of a portion of the recirculating water
. However, such measures are often cost prohibitive for large cooling s ys tems . In some locations, du st entrained from the air can be a major source of solids in the system . Certain BMP provisions to control dust, such as better control of ash piles and suppression of dust from roads and coal piles, may be helpful. Chemical treatment of cooling water generall y serves the purposes of prevention and control of one or more of the following:

 Biological fouling  Scale formation  Solids deposition  Corrosion Treatment for control of biological fouling is almost universally practiced in both once
- through and rec irculating s ys tems . Biocides are often injected on an intermittent basis , and so the amount used is not as dependent on the cooling water s ys tem input and output flow s as are other chemicals that must be maintained at a constant dos age in the recirculatin g system . Thus, while some change in the amount or ty pe of biocide used may

occur when converting from once
through to recirculating cooling towers or when changing the cycles of concentration of a cooling tower , the change should not significantl y alter treatment costs for biocides use . For many power plants , including those that currentl y use cooling towers, chemical treatment with biocides such as chlorine (including possible dechlorination of the effluent) is the only chemical addition that is associated with cooling water use. For many cooling towers , the operators generall y operate the towers at a COC low enough to avoid serious solids
- and scale
- related problems . Problems not related to biofouling are dealt with using a non - chemical maintenance approach such as periodic system cleaning to deal with solids and cathodic protection , and ultimately equipment replacement to deal with corrosion. Recirculating s ys tems operating at higher cycles of concentration will develop correspondingl y higher concentrations of the dissolved solids, hardness, and alkalinity in the make
-up water , which can result in problems with respect to scale formation. The formation of calcium carbonate scale is the result of a reaction of calcium hardness with alkalinity. One o f the simplest treatment methods for control of calcium carbonate scale is the addition of acid (such as- 8
-

sulfuric or hydrochloric acid) to the make
-up water , which reduces the alkalinity
. In this treatment method, enough acid is injected into the make
-up water to reduce the total alkalinity to 50 to 100 ppm and maintain the pH of the cooling water within the range of 6.8 to 7.5 (Harfst, 2008)
. However, treatment with acid must be carefully controlled to prevent an excessively low pH , which c ould lead to c orrosion problems and involves the risk of onsite storage of large quantities of a hazardous material. Another common treatment chemical useful for preventing scale formation is p hosphonate
. Phosphonate control s scale by adsorption onto crystal surfaces disrupting the crystalline structure of calcium carbonate
. A ty pical dose of phosphonate f or a cooling tower operating with a COC in the range of 3
- 6 would be 2
- 4 ppm (Keister 2009)
. The term “ dose ” as used here is the concentration that must be maintain ed in the recirculating water . As such, the rate of chemical addition associated with any dosage will be dependent on the rate of depletion , such as loss through blowdown , drift , and degradation
. A common treatment chemical useful in controlling solids deposition is p o lyacrylate. Polyacryl ate acts as a dispersant and is very effective at controlling solids with partic l e size s of 2 microns or less. For cooling towers operating with a COC in the range of 3
- 6 , a ty pical dose of p olyacrylate would be 4
- 5 ppm (Keister 2009) As a cooling tower ’ s water efficiency is increase d by increas ing the cycles of concentration, a point will be reached where treatment chemicals may be come necessary , and the dosage will increase as the COC increases beyond that point
. Thi s may also result in an increase in costs for more frequent monitoring of tower water quality and control of blowdown rates. However, the associated reduction in blowdown volume will also result in a reduction in the rate of chemical lost from the system. Treatment chemical vendors are able to evaluate the variation in chemical costs associated with these tradeoffs and recommend the optimum level that minimizes chemical and other operating costs while also minimizing risks. One treatment chemical vendor said that the optimum level for most industrial cooling towers is at a COC ranging between 3 and 6, with the lower end being applicable to s ys tems with high hardness make
-up water (Keister 2009). Estimated Costs for Modifications to Operate Cooling Tower s at Higher C ycles of Concentration Operating at higher COCs in the range of 3 to 6 or higher for freshwater s ys tems and 1.5 to 2.0 for saltwater s ys tems requires more precise control and monitoring of the blowdown rate and use of additional treatment chemical to control solids and scale. The following added costs may be necessary :

 Capital cost s for a make
- up flow meter and control system ;  Capital costs for chemical feed s ys tems for up to two chemicals such as polyacrylate and phosphonate;  O&M costs for additional chemical treatment ; and  O&M cost s for additional labor for s ys tem maintenance, monitoring , and laboratory anal ys is.- 9
-

To illustrate these additional costs and to estimate scalable cost factors for the increased costs of operating at a higher COC, an example cooling tower configuration was developed. In this example, chemical treatment is assumed to include a scal e inhibitor such as phosphonate for both saltwater and freshwater systems , plus a solids control chemical such as polyacrylate for freshwater s ys tems. While these chemicals serve as examples for cost estimation purposes , o ther chemicals may

be substituted where appropriate with little change in costs (Keister 2009B)
. All c osts are assumed to be linear and are expressed in dollars/gpm o f recirculating flow. The costs are based on a nominal system with the following design:

 A recirculating flow rate of 100,000 gpm  A ∆ T of 15  F  A COC of 4 .0 for freshwater s ys tem s and 1.5 for saltwater s ys tems Table 4 below provides the corresponding design data for a 100,000 gpm recirculating flow cooling tower
. Table 4

Chemical Cost Design Assumptions for a 100,000 gpm Cooling Towe r COC = 4.0 COC = 1.5 Make
-up (gpm) 1,700 3,825 Blowdown (gpm) 425 2,550 Polyacryl ate D osage (ppm) 3.0 3.0 Phosphonate Dosage (ppm) 4.5 4.5 Additional Labor (hrs/day) 1.0 1.0 Capital Costs Capital cost s for the make
-up control s ys tem and chemical feed s ys tem in the example cooling tower are based on the following costs:

 Flow meter for 1270 gpm make
-up piping costs $4,000 or $2.80/gpm (Keister 2009) ;  Chemical feed s ys tem cost s $3,000 per chemical;  Installation c osts are 100% of total equipment cost s ; and  Other indirect and direct costs including controls, electrical, engineering, site preparation, contingency , and allowance are 100% of total installed costs. Based on the above assumptions, the capital costs for upgrading a recirculating cooling tow er system to operate at higher COCs is $43,000 for freshwater and $55,000 for saltwater for a 100,000 gpm s ys tem or $0.43/gpm and $0.55/gpm, respectivel y. This is a relatively small one
time cost item representing about 0.2% of the capital cost of an average difficulty cooling tower system. 4

4 Using the EPRI cooling tower design and c osting model, which assigns costs on various factors, including an assessment of the difficulty (easy, average, or difficult) for the tower retrofit.- 10
-

O& M Costs O&M costs consist primarily of the cost of treatment chemicals and added labor for monitoring and maintaining the s ys tem and conducting laboratory anal ys is of cooling water samples. It is assumed that the power plants have an onsite wet chemistry laboratory and maintenance staff and that these labor cost will only require an incremental increase in labor hours. O&M costs are based on the following assumptions:

 Cost of biocide treatment will not change significantly ;  Amount of treatment chemical added is equal to dosage times the volume lost to blowdown plus 1 0% to account for degradation; 5  Average unit cost of treatment chemicals is $4.00/lb 6 of active ingredient;  Total added labor is 1.0 hour/day per 100, 000 gpm of rec irculating water (based on BPJ); and  Labor rate is $54/hr based on the $41.1/hr labor rate used in the Phase II cost modules adjusted for inflation from 2002 to 2009 dollars. Table 5 shows the resulting costs for a 100,000 gpm cooling tower. Table 5 Estimated Increase in O&M Costs for Optimized Operation of C ooling Towers COC = 4.0 COC = 1.5 Chemical Costs $61,000 $148,000 Labor $20,000 $20,000 Total $81,000 $168,000 Unit Costs/gpm $0.81 $1.68 Based on the above methodology , these cos ts can be considered as representative of the added costs to operate at higher COCs on a broad scale , but actual costs will vary based on site
- specific water quality conditions
. The average of these two values is $1.25/gpm and i s nearl y equal to the non
-p ower - related net increase in O&M costs derived from the EPRI model that was used in calculating cooling tower costs for the revised Phase II rule development
. The exact details of EPRI ’s cost methodology are not known (i.e., which cost elements are included and what assumptions were used , but given that they are intended to be representative of past experience, it is reasonable to assume that the EPRIcosts are based on the current practice of operating at lower COC values with minimal treatment using bioc ides. Thus, the above costs represent the incremental increase in O&M costs that should be added to cooling tower retrofit costs as well as for existing plants required to operate at higher values of COC. The COC that can be achieved with such a chemical treatment scheme will be dependent on the quality of the make
-up water , but at a minimum should be in the range of 3
- 6 for freshwater s ys tems and 1.5 to 2.0 for saltwater s ys tems.

5 Based on conversation with Timothy Keister, ProChemTech International Inc. 6 Approximate average based o n estimated chemical cost of $3.44/lb and $4.25/lb active ingredient for phosphonate and polyacrylate, respectively. These costs are adjusted upward using a 40% markup and 5% tax from purchase costs reported by a chemical vendor of $2.34 and $2.89, respec tively (Keister 2009).- 11
-

Cooling Tower Media Cooling tower media serves the purpose of increasing the interaction of water and air b y slowing down the rate at which water drops through the tower and b y increas ing the surface area of the air/water interface. There are generall y two kinds of media: splash fill and film fill. Splash fill consists of material that intercepts water droplets and redirects (splashes) them as they move down through the tower. Film fill is composed of thin corrugated plastic sheets upon which the water flows as a thin film. Film fill tends to produce a more efficient heat transfer , but is more susceptible to plugging by solids and requires the initial spray s ys tem to be capable of providing a more uniform distribution of water droplets. Thus , while film fill may be more efficient it is also more likely

to experience operati onal problems requiring maintenance. The ty pe of fill can affect the air pressure drop across the media , which in turn affects the air flow rate through the tower. Within the different ty pes of media are numerous design modifications that could result in tradeoffs between system efficiency , maintenance costs and the potential for operational problems. For example, a film fill with smaller channels may be more efficient than one with larger channels because of the greater water surface area , but may also be more prone to plugging with solids , which could result in lowered efficiency and higher maintenance costs. Decisions regarding selection of fill ty pe and design must take into consideration the expected tower efficiency, water quality , spray s ys tem de sign requirements, the control measures to be employed both chemical and physical, and expected maintenance requirements. Use of film fill in towers where solids control is not adequate may result in a requirement to periodically clean the towers to remov e the solids , and under worst
- case situations the tower media may become so plugged that the media must be completely replaced.- 12
-

References Carney , Barbara. Feeley , Thomas J. McNemar, Andrea. NETL Power Plant water research Program. EPRIAdvanced Cooling Technology workshop. July

9, 2008. Daniels, David. M&M Engineering Associates, In c. Put a Lid on Rising Chemical Costs. POWER Magazine. September 15, 2008. (http://www.powermag.com/issues/features/1347.html DOE EIA. Electric Power Industry Overview
- Electric Power Generation. Accessed on June 17, 2009 at website: http://www.eia.doe.gov/cneaf/electricity /p age/prim2/chapter3.html Drbal , Lawrence F. Boston , Patricia G. Westra , Kayla L. Black & Veatch
. Power Plant Engineering
. 1995. Engineering Tips. Chemical Process Engineering FAQ

– Cooling Tower

– How to calculate cycles, blowdown, evaporation, make
-up. Accessed on October 20, 2009 at website: http://www.eng
- tips.com/faqs.cfm?fid=1152 Harfst , William F. Enhanced Cooling Tower Maintenance Saves Water
. Maintenance Technology . October 2008. http://www.mt
- online.com/article/1008
- Enhanced
- Cooling
- Tower
- Maintenance
- Saves
- Water Keister, Timothy
. ProChemTech International Inc. Log of telephone convers ation with John Sunda. SAIC regarding technical, treatment chemical usage, and cost issues regarding the impact of increasing cycles of concentration (COC) in cooling towers August 25, 2009. National Productivity

Council of India (NPCI). Guide Book 3

– Energy Efficiency

in Electric Utilities. Chapter 7

– Cooling Towers. No Date. Accessed on March 25, 2009 at website: http://www.em
- ea.org/Guide%20Books/book
- 3/Chapter%203.7%20Cooling%20Tower.pdf
. Nelson, John A. Marley

Cooling Towers. Cooling Towers and Saltwater. November 5, 1986. http://spxcooling.com/pdf/CTs
- and
- Salt
- Water.pdf- 13
- Appendix A

De lt a T Circu la ti ng

wa te r Ma ke- up

Water Bl owd own Evap or at i on Ev ap ra ti o

n % of Circ. Drift Cy cles of Conc Mak e- up

% of C irc. Per cent Reduction deg F gpm gpm gpm gpm gp m Xc /X m 10 100 ,000 9,35 0 8,49 9 85 0 0.9 % 0. 5 1.1 9.3% 90 .7% 15 100 ,000 14,02 5 12,7 50 1,27 5 1.3 % 0. 5 1.1 14.0% 86 .0% 20 100 ,000 18,70 0 17,0 00 1,70 0 1.7 % 0. 5 1.1 18.7% 81 .3% 25 100 ,000 23,37 5 21,2 50 2,12 5 2.1 % 0. 5 1.1 23.4% 76 .6% 30 100 ,000 28,05 0 25,5 00 2,55 0 2.6 % 0. 5 1.1 28.1% 72 .0% 10 100 ,000 5,10 0 4,25 0 85 0 0.9 % 0. 5 1.2 5.1% 94 .9% 15 100 ,000 7,65 0 6,37 5 1,27 5 1.3 % 0. 5 1.2 7.7% 92 .4% 20 100 ,000 10,20 0 8,50 0 1,70 0 1.7 % 0. 5 1.2 10.2% 89 .8% 25 100 ,000 12,75 0 10,6 25 2,12 5 2.1 % 0. 5 1.2 12.8% 87 .3% 30 100 ,000 15,30 0 12,7 50 2,55 0 2.6 % 0. 5 1.2 15.3% 84 .7% 10 100 ,000 2,55 0 1,70 0 85 0 0.9 % 0. 5 1.5 2.6% 97 .5% 15 100 ,000 3,82 5 2,55 0 1,27 5 1.3 % 0. 5 1.5 3.8% 96 .2% 20 100 ,000 5,10 0 3,40 0 1,70 0 1.7 % 0. 5 1.5 5.1% 94 .9% 25 100 ,000 6,37 5 4,25 0 2,12 5 2.1 % 0. 5 1.5 6.4% 93 .6% 30 100 ,000 7,65 0 5,10 0 2,55 0 2.6 % 0. 5 1.5 7.7% 92 .4% 10 100 ,000 1,70 0 850 85 0 0.9 % 0. 5 2.0 1.7% 98 .3% 15 100 ,000 2,55 0 1,27 5 1,27 5 1.3 % 0. 5 2.0 2.6% 97 .5% 20 100 ,000 3,40 0 1,70 0 1,70 0 1.7 % 0. 5 2.0 3.4% 96 .6% 25 100 ,000 4,25 0 2,12 5 2,12 5 2.1 % 0. 5 2.0 4.3% 95 .8% 30 100 ,000 5,10 0 2,55 0 2,55 0 2.6 % 0. 5 2.0 5.1% 94 .9% 10 100 ,000 1,27 5 425 85 0 0.9 % 0. 5 3.0 1.3% 98 .7% 15 100 ,000 1,91 3 637 1,27 5 1.3 % 0. 5 3.0 1.9% 98 .1% 20 100 ,000 2,55 0 850 1,70 0 1.7 % 0. 5 3.0 2.6% 97 .5% 25 100 ,000 3,18 8 1,06 2 2,12 5 2.1 % 0. 5 3.0 3.2% 96 .8% 30 100 ,000 3,82 5 1,27 5 2,55 0 2.6 % 0. 5 3.0 3.8% 96 .2% 10 100 ,000 1,13 3 283 85 0 0.9 % 0. 5 4.0 1.1% 98 .9% 15 100 ,000 1,70 0 425 1,27 5 1.3 % 0. 5 4.0 1.7% 98 .3% 20 100 ,000 2,26 7 566 1,70 0 1.7 % 0. 5 4.0 2.3% 97 .7% 25 100 ,000 2,83 3 708 2,12 5 2.1 % 0. 5 4.0 2.8% 97 .2% 30 100 ,000 3,40 0 850 2,55 0 2.6 % 0. 5 4.0 3.4% 96 .6% 10 100 ,000 1,06 3 212 85 0 0.9 % 0. 5 5.0 1.1% 98 .9% 15 100 ,000 1,59 4 318 1,27 5 1.3 % 0. 5 5.0 1.6% 98 .4% 20 100 ,000 2,12 5 425 1,70 0 1.7 % 0. 5 5.0 2.1% 97 .9% 25 100 ,000 2,65 6 531 2,12 5 2.1 % 0. 5 5.0 2.7% 97 .3% 30 100 ,000 3,18 8 637 2,55 0 2.6 % 0. 5 5.0 3.2% 96 .8% 10 100 ,000 1,02 0 170 85 0 0.9 % 0. 5 6.0 1.0% 99 .0% 15 100 ,000 1,53 0 255 1,27 5 1.3 % 0. 5 6.0 1.5% 98 .5% 20 100 ,000 2,04 0 340 1,70 0 1.7 % 0. 5 6.0 2.0% 98 .0% 25 100 ,000 2,55 0 425 2,12 5 2.1 % 0. 5 6.0 2.6% 97 .5% 30 100 ,000 3,06 0 510 2,55 0 2.6 % 0. 5 6.0 3.1% 96 .9% 10 100 ,000 97 1 121 85 0 0.9 % 0. 5 8.0 1.0% 99 .0% 15 100 ,000 1,45 7 182 1,27 5 1.3 % 0. 5 8.0 1.5% 98 .5% 20 100 ,000 1,94 3 242 1,70 0 1.7 % 0. 5 8.0 1.9% 98 .1% 25 100 ,000 2,42 9 303 2,12 5 2.1 % 0. 5 8.0 2.4% 97 .6% 30 100 ,000 2,91 4 364 2,55 0 2.6 % 0. 5 8.0 2.9% 97 .1% 10 100 ,000 94 4 94 85 0 0.9 % 0. 5 10 .0 0.9% 99 .1% 15 100 ,000 1,41 7 141 1,27 5 1.3 % 0. 5 10 .0 1.4% 98 .6% 20 100 ,000 1,88 9 188 1,70 0 1.7 % 0. 5 10 .0 1.9% 98 .1% 25 100 ,000 2,36 1 236 2,12 5 2.1 % 0. 5 10 .0 2.4% 97 .6% 30 100 ,000 2,83 3 283 2,55 0 2.6 % 0. 5 10 .0 2.8% 97 .2% Assu me d Ev apor ati on Ra te 0.000 85 Assu me d Dr

if t r at e 0. 0000 05

Cool in g Towe r Fl ow

Cal cu latio ns