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Paper No.
494
COIRROSIONC)LThe NACE International Annual Conference and
Exposition
UPDATEOF OZONE USE IN COOLING TOWERS
PAUL R. PUCKORIUSPuckorius & Associates, Inc.
PO BOX 2440Evergreen, CO 80437-2440
ROBERT T. HESSPuckorius &Associates, Inc.
PO BOX2440Evergreen, CC)80439
ABSTRACT
Ozone use in cooling towers has continued, but at a much lower
rate of expansion than five(5) years ago. The reasons for this
reduction are primarily due to a better understanding of theozone
performance requirements. Ozone is not a complete treatment in most
cases and islimited due to high costs for installation. Specific
case histories are reviewed along with updatedguidelines for ozone
applications and economic evaluation.
INTRODUCTION
Ozone has been reported to be a complete treetment for cooling
tower systems for scale,corrosion, and biological control. These
claims often are not verified. When investigated, thoseapplications
that appear to provide complete treatm:nt actually involve the
presence ofchemicals or water reactions not directly caused by
ozone but indirectly related.
Ozone applications have been analyzed in detail which show ozone
as a goodmicrobiological, with some major limitations; yet an
excellent Legionella bacteria control agent.Scale inhibition is
unpredictable and often ineffective. Corrosion inhibitor on mild
steel isprimarily related to high pH and alkalinity, not ozone.
Substantial increase in copper corrosionand copper plating on mild
steel and galvanized ste:l, with greatly increased corrosion
andpitting is common.
It has bee noted that many ozone applications wwe initiated in
chemically treated coolingwater systems that had previously
unacceptable results which certainly is a driving force to tryany
alternate technologies.
These reports included early ozone use as well ~s recent ozone
use. This inconsistencyprompted detailed, independent evaluations
of numerous ozone applications. The results ofthese evaluations
have contributed to the development of guidelines for end users
whenconsidering ozone use.
CopyrightICl996 byNACE International.Requestsforpermissionto
publishthismanuscriptin any form, in part or in whole must be made
in writing to NACEInternational, Conferences Division, PO. Box
218340, Houston, Texas 77218-8340. The material presented and the
views expressed in thispaper are solely those of the author(s) and
are not necessarily endorsed by the Association. Printed in the
U.S.A.
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A number of ozone applications during the last 2 years have been
discontinued due to highcosts, ineffective performance, and
excessive maintenance. This trend is due to initial overemphasis of
benefits that proved to be misleading or erroneous. Details of some
of thesediscontinued ozone applications are provided within this
report.
We have also evaluated a number of succe!$sfulapplications of
ozone in cooling watersystems. Their successes have contributed to
the development of the guidelines as to whereand how ozclne can be
applied effectively. Details of some of these continuing
ozoneapplications are provided within this report.
COOLING SYSTEM CRITERIA/ CONCERNS WITH OZONE
As a basis for evaluating the use of ozone, it is extremely
important to understand coolingwater systems. The basic water
cooling tower systems (Figure 1), can vary extensively indesign,
operation, and occurrence of contaminants when utilized in
different industries. Thesevariations are critical in predicting
the performance and cost effectiveness of ozone (as well asother
chemicals) in protecting water cooling tower systems. Specific
criteria to be considered inpredicting ozone effectiveness are:
a) Ozone demand due to organic andjor oxidizable inorganic
reducing agents entering thewater cooling tower system from the
makeup water, air, and/or process contamination;
b) The time to circulate water through the entire cooling
system; that value obtained bydividing the system volume by pumpin~
rate. Ozone is less effective if greater than 10minutes.
c) Hide-outareas for bio-mass such as in water-on-the-shell-side
heat exchangers, withincooling tower film fill, deep basins, and
periodically stagnant equipment.
d) Corrosion of copper (if over 0.2 mpy) and mild steel (if over
1.0 mpy) with no pittingattack nor copper plating on steel or
galvanizing.
e) Water temperatures (over 100F(380C)]which willquickly
deactivate ozone.
Specific objectives for successful ozone use are:l No loss of
heat exchange due to deposition.l No fmicrobiologicalgrowths,
including Legionella.l Zero voluntary discharge.l Greater cycles
than with chemical treatment.l Decreased water usage.l Recluced
costs vs. conventional chemical treatment.l Reduced labor.l
Eliminate chemical handling.l Achieve low maintenance.
COOLING TOWER SYSTEMS/ OPERATIONS/ DESIGN
Cooling tower systems differ for each major industry relative to
design and operatingcharacteristics. These differences must be
understood when evaluating ozone as well as othertreatment
programs. These industry specific criteria apply when ozone is the
onlytreatmentutilized. Hclwever,they may not apply when ozone is
used with other compatible chemical
494/2
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treatments. Thefollowing criteria are based on ozone use in
North American cooling systemsand may not apply to industries
throughout the world since success has occurred in Australia,Japan,
and Europe.
HVACor Air Conditioning SystemsHVACor air conditioning systems
(Figure 2) are perhaps the best suited for successful ozone
use with this design. They seldom have major atmospheric, makeup
water or processcontaminaticln that consumes ozone. The time per
cycle usually is less than 10 minutes, due toa small system
capacity to recirculation rate ratio. Temperatures seldom exceed
100F(380C).
The design shown in Figure 2 illustrates the }-WACsystems that
can have one or several airconditioning (condensers) and they all
have water on tube-side water (WTS) cooling, which ismuch easier to
keep clean than water on shell-s de exchangers. The materials of
constructionare heat exchanger (condenser) tubing of copper or
copper alloy that can tolerate 0.5 to 1.0 mpy(roils per year) and
perhaps higher, and mild steel piping that can tolerate 5 mpy
corrosion rates.These systems are relatively easy to treat for
biomass. Ozone can be effective, but may notalways be cost
effective.
There are two (2) additional design considerations in
HVACsystems that are deterrent toozone (and chemical treatment)
use. The first i:; the utilization of waterside enhanced
coppercondenser tubes and cooling tower film fill. The enhanced
copper tubes have grooves or shallowfins that require outstanding
cleanliness and corrosion protection for satisfactory
life-expectancy.The cooling tower fill,when film-fillis utilized,
also must be kept clean of deposits to maintaindesign evaporation
and heat rejection.
The seccmd design consideration for HVACcooling tower systems
that willadversely impacton ozone effectiveness is when heat-pumps
or small chillers are used. This results in piping oflong lengths
(and much greater time per cycle) for the cooling water passing
from the coolingtower to the heat pumps in each office, condo, or
store within a large complex and returning tothe cooling tower.
With these designs, ozone is usually ineffective.
Oil Refineries and Chemical PlantsThese (Figure 3) are generally
poor candidates for ozone use as a stand-alone treatment.
This is due to high ozone demand created by olganicsand
inorganic entering these systemsthat oflen cannot be satisfied by
the ozone generating equipment. The time per cycle is often
20minutes or more due to complex systems and deep basins. The water
temperatures oftenexceed 130F (54C). Both of these factors cause a
rapid loss of ozone and the inability tomaintain effective ozone
residuals without mult injection locations.
These cooling tower systems often have many heat exchangers,
often with water on the shellside (WSS), and many use mild steel
tubes that require very good corrosion protection with ratesof 0.5
mpy (orless corrosion and ~ pitting. Ths is attainable with
standard chemical treatmentprograms and not with ozone.
Utility Fossil StationsThese (Figure 4) also are considered
relatively poor candidates for effective ozone alone
use, but for different reasons. They can have moderate to high
organic loading due to use ofuntreated raw makeup water that can
contain relatively high organic loading, high suspendedsolids, and
bioorganisms. These plants generally have a very long time per
cycle, often in
49413
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excess of 30 minutes. This is due to their large capacity versus
the circulation rate. The watertemperatures are usually mild
(1OOF(38C)or less) but can exceed 120F (49C). Generallythese
conditions can result in very high or excessive and uneconomical
ozone use, unlesschemicals such as bromide ion is present or added
for improved bio-control.
UtilityNuclear Power StationsUtilitynuclear power stations
(Figure 5) are also considered poor candidates for ozone alone
use for many of the same reasons as the fossil fuel stations.
Yet, this depends upon the specificsite cooling water system
design. Ifthe service water and condenser water are combined,
ozoneuse is ineffective and not practical due to the presence of
redundant safety-related service waterequipment that have little or
no water flow during normal operation. This prevents ozone
fromentering and effectively treating the system at cost effective
dosages.
Steel MillsSteel mills (Figure 6) also are often generally very
poor candidates for ozone alone use
since they are often quite similar to refinery/chelmical plant
design/operation. They generallyutilize poor quality makeup water
and encounter considerable atmospheric and processcontamination
from dirt, dust, iron oxide, and sulfurous gases that cause an
excess ozonedemand. These cooling tower systems generally are also
very complex with jacketed cooling(water on shell side), multiple
heat exchangers, long time per cycle due to large system
volumeswith relatively low circulating rates, and water
temperatures commonly exceeding 120F{490C).These are excess ozone
consumers and thus prevent the effective use of ozone. Should
theybe absent, ozone could be effective.
Light Manufacturing Industry Cooling SystemsThese often are
similar to the HVACcooling systems (Figure 2) and can be good
candidates
for ozone use. Ifdesign is more like refinery chemical plants,
then there is excess ozonedemand or rapid ozone loss, these
criteria would reduce the potential for successful ozone use.
A summary of ozone use versus industries is given in Table
1.
OZONE CONSUMERS
Ozone is not usually cost-effective when makeup water chemical
oxygen demand (COD)levels are high (above 20 mg/1). This is due to
easily ozone oxidizable organics. Ozone is such arapid reactant,
that biomass hid-outin some heat exchangers may not be reached
andcontrolled.
Another predictable ozone properly is temperature degradation.
It is known that ozone isdestroyed more rapidly as the water
temperature increases. A temperature of 130F (54C)causes rapid
destruction. Recent evaluations of case histories indicate that
even temperaturesof 100F(380C) are considered to be excessive and
result in rapid ozone destruction.
Cooling Tower Contaminants/Sources/Ozone Consumers
- Makeup water -
orgarlics/bio-organisms/ammonia/iron/manganeselswlfideslnitrites
- Atmospheric -
organics/ammoniakxdfideskwlfurdioxide/bioorganisms
494/4
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- System - oils/organics/iron/copper/galvanizing/plastics/filter
media/wood and woodpreservatives
CASE HISTORY & OZONE RESULTS
Any water treatment performance evaluations must include
sufficiently detailed techniques toprovide accLlrate, consistent
data. They must include testing for corrosion, deposition,
biological,and water quality as well as knowledge of the system
metallurgy, operating characteristics, anddesign. AISCIacceptable
system protection for each parameter must be established such
ascorrosion rates, amount of deposition, etc. Certainly economic
evaluations willdetermine
therelativebenefitsandacceptanceofozoneversusalternatetreatmentprograms.
The followingcase histories provide effective detailed
evaluations of ozone use in severalcooling water systems.
CASE HISTORY#1
System SpecificsThis HVACsystem provides a maximum design of
3000 tons (1) of refrigeration which serves
comfort and computer cooling requirements. It includes four
cooling towers, two with 1000 Tcapacity each, and two with 500T
each. The cooling towers operate as one system, with 2000 Tbeing
the normal operating load and the remaining 1000 T as backup (see
Figure 7).
Water vclume of the system is approximately 10,000 gallons. The
water recirculation rate atmaximum normal operation is 6000 gpm.
Thus, time per cycle is 1.66 minutes; very short. Insummer, the
cooling towers receive maximum water temperature at 110F(440C)
maximum andcool to 90F(320C), a 20F(-140C)At at top heat load. The
system operates year round. Winterwater temperature, due to free
cooling, is 45 to 50F(7 to 10C). Makeup is a very lowhardness and
low alkalinity potable city water. I_hesource is clarified river
water (see Table 11).
The reciprocating refrigeration machine condensers are
fabricated with smooth copper tubes,mild steel tube sheets, and
mild steel water boxes. Water is through tubes. The circulating
linesare mild steel. Two cooling towers are wood with PVC film fill
and two are fiberglass withceramic fill.
Prior to the use of ozone, the previous treatment was a
conventional cooling towerformulation consisting of: a scale
inhibitor (HEDP), a mild steel corrosion inhibitor (zinc), acopper
corrosion inhibitor (TTA)and a dispersant (polyacrylate); with no
pH control. The pH fellbetween 8.0 and 9.0 at 3-6 cycles (COC).
Both a hydantoin (bromine release agent) and a non-oxidizing
biocide (DBNPA)were used for microloiologicalcontrol.
The chemical treatment was monitored for one year, to obtain a
base of performance beforethe ozone program was put into operation.
Control of chemical feed and COC was erratic due tofluctuating
c~peration and inadequate chemical teed equipment. The maximum
number of COCobserved was six, as recommended by the supplier.
Water treatment costs were about US$17,600 per year. Results were
considered to be not good. They showed higher than desired
494{!5
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(less than 3 mpy) mild steel corrosion rates of 6 to 9 mpy, with
pitting and local attack; and onlyfair copper corrosion rates of
0.2 to 0.4 mpy (desired was 0.2 or less); also, some scale
andmicrobiological deposits were occurring).
The ozone generator was of the corona discharge type, capable of
producing 28 pounds ofozone per day from dry air. Normal ozone load
was 35 to 40 percent of generator capacity. Theozone-air mixture
was fed through diffusers in a six foot deep sump. Off-gas was
drawn into thetower and expelled by the fans.
Corrosion MmitoringOnce be{iun, the ozone feed rate settled into
providing a residual of 0.18 mg/1at the sump
pump. COC ranged initiallyfrom 6 to 8 (see Ta!oleIi). Corrosion
rates in roils per year (mpy)over the first 15 months, as measured
on 30 and 60 day coupons were:
MildSteel QQM2!2! 316 Stainless4.5 1.26 0.022.3 1.064,2 0.69 304
Stainless3.1 0.39 0.054.5 0.86 0.083.2 0.81 0.021.5 0,391.31.8
Admiralty Galvanized Steel2.2 0.26 0.262.2 0.603.1 0.354.44.5 90:10
Cu:Ni
0.10
While the corrosion rate values for mild steel coupons are not
too alarming, the couponappearance was. Pits on all mild steel
coupons during the 15 months that the system wasmonitored were too
numerous to count. In many of the pits, a copper color could be
seen, andcopper was confirmed by scanning electron microscope with
X-ray probe. In some areas notpitted, the steel surface was copper
plated. In some instances, the copper remained on the steeleven
after slcid cleaning.
Copper and copper alloy coupons were often covered with a dark
brown adherent coating.This was fir%assumed to be a patina similar
to one that forms on weathered MonelTMmetal, andwhich might offer
some corrosion protection. However, when immersed in acid for
cleaning, ared precipitate formed from the brown coating which
deposited as a powdery film on the coupon.Most of the film could be
removed with a nylon brush. What remained gave all the copper
andcopper alloy coupons darker appearance than a new coupon of the
same material, and 9enerallydarker than-a coupon used in a
chemically trea~ed closed system.
It was also observed that much of the metal loss on copper and
copper alloyunder the coupon holder or the inert washer andior in
the stamped numerals.
494/6
coupons was
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Since crevice (or under-deposit) corrosion often is due to
differential oxygen cells, ozonebeing a stronger oxidant than
oxygen was likely to create a more potent differential oxidant
cell.To study this possibility, a set of coupons was doubled up on
the same holder: two mild steelcoupons, copper coupled with an
Admiralty brass coupon, and 304 coupled with 316 stainless.Also a
rubber band was wrapped tightly around two mild steel coupons to
determine if excesscorrosion was occurring in crevices. The mild
steel coupons were upstream of the copper andthe copper upstream of
the stainless. Allwere left in the system for 82 days.
The two mild steel coupons had faced each other to form the
crevice. Most of the corrosionwas where the edges touched. The
corrosion rates for these two coupons were 4.4 and 4.5 mpy,higher
than the average of the previous coupons.
The copper and Admiralty coupons bolted together to form a
crevice, showed somediscoloration and a mild general etch.
Corrosion rates were 0.39 and 0.35 mpy respectively.Mildsteel
coupons from the ozone-treated system were red due to precipitated
copper.
The results show that ozone is corrosive to copper and its
alloys, and the dissolved coppercan then plate out on steel and set
up a galvanic corrosion cell.
The stainless steel coupons were clean, and had excellent
protection. Corrosion rates were0.02 mpy.
No indications of scale formation were observed anywhere in the
system. Dirtywhiteparticles, like sand, were found in the tower
basin. These analyzed as calcium carbonate,calcium silicate and
silica. The water quality (Table Ii) shows that loss of calcium,
silica, andalkalinity is occurring compared to the chloride
Ie\rels.
There were no biological deposits in the system but the towers
had some algae on areas thatare wet intermittently. The water was
always crystal clear.
Results were considered acceptable with still a concern over the
copper corrosion.
The cost ofelectricity for the operation of the air compressor
and the ozone generator wasUS $2,066 for twelve months of
operation.
CASE HISTORY #2
System SpecificsThis cooling system provides air conditioning on
a college campus. It consists of two(2) 900
ton absorption refrigeration machines, of which only one is in
use at a time. Condenser tubematerial is 95:5 copper/nickel. Tube
sheets and water boxes are steel and all circulating pipingand
valves are steel. Circulating pump housings are cast iron;
impellers are bronze. Water isthrough tubes.
There are three 300 T cross-flow galvanized steel towers with
stainless steel basins. Thethree basins are connected to a common
suction (supply) header. The return water isproportioned to both
ends of the three towers. System volume is estimated at 4,000
gallons.
4947
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Maximum load is 900 T; circulation rate 2700 gpm. Thus, time per
cycle is 1.5 minutes.Each tower has a capacity of 900 gpm. Cooling
tcwer has film fillhoneycombed PVC; fanblades are aluminum. Desi~n
AT~F) is 16, but can range from 14 to 23 in service.
Maximumtemperatures were 95F (35 C).
The towers and the circulating piping are only two years old and
were started up on ozone.However, the two absorption machines are
nine years old. There was no previous treatment asthe chillers were
originally on once-through river water. The condenser tubing was
acid cleanedprior to ozone use.
The ozone generator has a capacity of six(6) pounds per day of
ozone. At a circulation rateof 2700 gpm and fullgenerator capacity,
the maximum dosage of ozone would be 0.185 mg/1,assuming complete
dissolution. However, the povveron the generator was generally only
50percent of capacity. The dosage was therefore est[mated to be
0.09 to 0.10 mg/1of ozone,although this high a residual was never
found. Oz.cmewas monitored for four (4) months andshowed less than
0.07 mg/1. The makeup water quality and system water quality is
provided inTable Ill. This data shows COC of 4-18 depending upon
the water ingredients.
MicriobioMonitoringTotal bacteria counts (dipslides) were 104to
1CIScolonies per ml; however, the water was
sparkling clear and there were no slime or algae deposits on any
equipment.
Corrosion MonitoringCorrosion was monitored with coupons and a
linear polarization corrosion rate monitor.
Corrosion rates in mpy over this period were:
MildSteel6.355.8624,154.387.077.22
Galvanized Steel4.98
Copper0.270.180.340.190.21
Admiralty0.350.51
304 Stainless 90:10 Cu/Ni0.08 0.13
316 Stainless 95:5 Cu/Ni0.10 0.13
The mild steel coupons looked very much like those in Case
History #1. There was a deepgeneral etch throughout the surface of
the coupon, almost a gouging effect. The corrosionmonitor reading
was constant throughout the test at about 6 mpy and did not show
the wideswings that the coupons showed.
494!8
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Copper coupons had the same dark brown coa:ingas in Case #1,
which released metalliccopper when cleaned with acid.
Copper/nickel coupons had lower corrosion rates than the average
of copper coupons andAdmiralty. 304 and 316 stainless steel rates
were excellent, Aluminum did very poorly; as didgalvanized
steel.
The highest ozone reading obtained in the tower basins was 0.07
mg/1,with an average ofabout 0.05 mg/1. There was probably not
enough contact time in this system for properdissolution. Return
water on top of the towers generally contained zero ozone. It is
interesting tonote that while this installation is operating at
less than half the ozone residual as Case #1, theyare experiencing
the same copper plating and pitting of mild steel. The water
quality (Table Ill)shows that silica and some calcium is being lost
based on chloride concentration.
Particles found in the basins analyzed as calcium carbonate,
calcium silicate and corrosionproducts(iron and copper oxides).
However, some scale in the cooling tower fillwas found
withequipment (chiller) inspection showing only a thin coating of
scale.
Treatment operations costs with ozone are calculated at US
$3,000 for nine(9) months (fourmonths for the AC season, five
months for computer cooling).
ADDITIONAL CASE HISTORIES
There have been additional case histories that have been
reported earlier that have shownvery good corrosion control when
ozone has been used alone. Investigation showed that
variousinorganic mild steel corrosion inhibitors were present due
to the ozone. One case history showedhigh nitrates (over 100
mg/1)due to inadequate drying of air. Another showed zinc levels
above3 mg/1as a result of galvanized steel corrosion. inorganic,
ozone compatible chemicals, such asmolybdates, phosphates, even
chromates have been used for improved mild steel
corrosioncontrol.
Several case histories have reported bromide addition with ozone
to improve biologicalcontrol and the persistence of oxidant
(bromine not ozone) in cooling tower systems.
CONCLUSIONS
These, and additional case histories have led us to the
following conclusions for ozone use:
1. Ozone has effectively controlled the growth of biological
organisms.2. Scale did not occur on heat exchange su[faces, even at
higher cycles of
concentration than was possible on the same water with chemical
treatment.3. Water analyses show that silica is lost mcwethan any
other mineral.4. Calcium carbonate and calcium silicate
precipitates occurred in the tower basin. Scale
also clccurred on tower filland in hot heat exchangers.5. Total
alkalinity decreases due to decomposition and/or precipitation as
carbonate.6. Chloride and sulfates cycle up linearly.7. Magnesium
hardness is not removed and concentrates similar to chlorides and
sulfates.8. Ozone treated cooling tower water is crystal clear.
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9. Ozone residuals decrease rapidly from the injection point,
are often zero at the return tothe tower and always lost through
the cooling tower fill.
10. Ozone has caused high copper corrosion I-ates with copper
plating on mild steelcoupons.
11. Ozone can cause high mild steel corrosion and pitting.12.
Crevice and under-deposit corrosion is ac~elerated with ozone.
Ozone clearly is a bio-control chemical, if it can reach all
areas of the cooling tower system.Corrosion of copper alloys is
often excessive, while mild steel shows pitting and occasional
highrates. Scale has occurred at higher temperatures but also in
HVACsystems. Ozone is totallyunpredictable for scale control. Scale
can be conirolled by water softening. Ozone applicationsrequire
much Imorestudy to determine how it can be used most
cost-effectively without creatingother serious problems. However,
ozone does appear to offer some major advantages overstandard
chemical treatments, principally better microbiological control.
Cost effectiveness issite specific and should utilize the economic
evaluation guidelines presented in an earlier paper.
Ozone use in cooling tower systems usually can be predictable
depending upon the specificindustry conditions found. Ozone is not
a panacea as a stand-alone treatment in most cases,but can be under
the right conditions. Ozone use with compatible chemical treatments
is morecommon toda!yversus earlier ozone-alone applications. The
chemicals most often utilized arebromides, to produce bromine for
improved bio-;ontrol; phosphates, molybdates, and zinc saltsfor
improved corrosion control; resistant polymers for scale control
(or use of softened or reverseosmosis makeup water), Ozone
applicability depends upon specific criteria that must beevaluated
prior to its consideration or use. (Table IV). Acceptable corrosion
performance may besimilar to standard chemical treatments. (Table
VI It is extremely critical to have adequatemonitoring toclls in
place to evaluate its performance. They should provide results
rapidly,before system damage occurs and include all effective
monitoring parameters as shown in TableV!. Ozone has a place today
in cooling tower sys[em protection, and likelywillhave a
greaterconsideration as well as use when a better understanding of
its mechanisms is developed andwhen a uniform method is used to
evaluate its co:st effectiveness.
GUIDELINESFOR OZONE USE
The followingguidelines for ozone use are based on the case
histories that have beenanalyzed and evaluated. These guidelines
are sysitem specific:
l Ozone as a standalone treatment is dependent upon
waterquality, system design, and operation. It is not applicable in
manycooling tower systems.
l Ozone is not effective with high c~rganicloading.l Ozone is
generally ineffective or unpredictable as to scale control or as a
scale
control agent or inhibitor.l Ozone causes copper alloy corrosion
and often mild steel pitting.l Ozone may not be effective for
bio-control throughout entire
cooling system.
49410
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REFERENCES
M.F. Humphrey and R.F. French, Cooling Tower WaterConditioning
Study, Jet Propulsion Lab.Publication 79-104, 15 Dec. 1979, JPL,
Pasadena, California.
Baldwin, L.L.et al, The Investigation and Applicaiion of Ozone
for Cooling Water Treatment,IWC-85-36.
W.K. McGrane, Ozone and Reverse Osmosis, Cclrrosion 93, Paper
483,
P.A. Burda, et al, Performance and Mechanisms of Cooling Tower
Treatment by Ozone,Corrosion 93, !Paper488
D. MillerFielclTesting of Cooling Tower and Hea: Exchanger
Performance Before and AfterInstallation of an Ozone Water
Treatment System, Reports ##161-90.18,461-91.4, PG&E,Technical
and Ecological Services, Sept. 1990.
R.C. Schwartz, Field Study - Ozonation of HVACRecirculating
Water,IWC-92-53.
D.J. Tierney, EiS. Feeney, R.A. Mott, Performance Evaluation of
Ozone Cooling WaterTreatment at t(ennedy Space Center:,
IWC-95-46.
P.R. Puckorius, Dileep Thatte, Economics of Ozone Application in
Cooling Water Systems,NACE, Corrosion 94, Paper 472.
Puckorius, P.R.; J. Maxey Brooke, Ozone For Cc~olingTower
Systems - Is It a Panacea?,NACEAnnual Conference, March 1991.
R.G. Rice, J.F. Wilkes, BiocidalAspects of Ozone for Cooling
Water Treatment- ProbableImpacts of Bromide IonCTI 92, Tech Paper
TP-92-07.
R.T. Hess, D. Puckorius, P.R. Puckorius, Polymws in Cooling
Water, Industrial WaterTreatment, March 1992.
R.G. Rice, Byproducts of Ozonation Formed During Treatment of
Water, Corrosion 93, Paper479.
494111
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TA%LE 1. APPLICABILITY OF C)ZONE veins INDUSTRY
Industyv
HVAC
Oil RefineriesL
Chemical Plants
Utilities - Fossil
Utilities - Nuclear
Steel Mills
Light ManufacturingJ?
Ozone Applicability
Good
Very Poor
Vew Poor
Poor
Vem Poor
Poor
Good
-
494/1 3
-
. .._--L_-l __ ....-.-1-.. ..__ 1-..... .---- .-1-------- L
------------ _.-.~.-~-_.__ -.-._
-------CASE HISTORY#2 - DURING INITIALOZONE
USE:y:7=-----TA~T7;---~--------7---T
---j ------ -- --------- -------- --------- --+-----------..._
._ ___ . . ___ ....___
- :p~r:=:-----
.-.---....
. 1I - ~==----
_-
ParameterE
I 1- --------.
:i : g;~;:n::
_
. . .-
l.. ._. _ _______ . ______
--1----------- -------- ---- .N;A- ---~ -:---- --------
----------..-.-.__.I,__: ------ ::-_-:_T::-.:I:_. - ___ ;,_.._.
___
--.-:_.l:_
:;a$:,=:~=;:;:::+::~::]_j;::.
-1-44- -------- -N[A- ------- -------- -------
E::?F:~;$~:~$:~::
~
~ , __ ---32 .. .. _________._____..ioo
. l-_._._-.. ._-. ---- ..- ______ _ ~:g _ . .-. ---- ~TA..... ..
.... -- .-..-.. ,.Nitrate as NOS__._~J_--_____
Trace
1
_. ...
Iron, Ferrous---,_---- O!:.._.
- t: l-----~---=f
...
.-. +._. ..> . ---
:: !Q~~.lrX2!2 .~....
;;~~{+=: f+:i:;l;:i-==E:;-
Copper, total, in solut
&Zs~i;
_ ---,::----;:j:,~;:z~:~=~;=~;=-:-
;Z:::~j:----[~3=-l=-l~~~~~~
...--.-+. ..-.-. --------- -------- ___ _____
--:!=!----[-------=-..--. - 1.. --._-\-.._--._. _ .. . . . ... .
. .. ... .. .... . .~ _-__--:
49L/14
-
1.
2.
3.
4.
Ieiu l-i-. Iv
COOLING TOWER SYSTEMS
CRITERIA DETRIMENTAL TO
Ozone Consumers
ECONOMICAL OZONE USE
u Makeup water organics/iron/manganese/ammonia/bio-organisms
n Atmospheric organics/amrnonia/sulf ides/sulfur dioxide
- Process/organics/ammonia/sulfides
Retention Time: Time/Cycle = Capacity/Recirculating Rate
u Over ten (1 O) minutes
Large Water Use
D Over 1 million gallons per day
Temperature
- Over 11 OF
49415
-
TABL.E VACCEPTABLE CORROSION RATES (MPY)
Heat Exchanger Tubes NAS 0.5 MPY or less
Heat Exchanger Tubes (: u 0.2 MPY or less
Heat Exchanger Tubes sa 0.2 MPY or less
Lines MS 3-5MPY
All Cases -- no pitting
MPY = roils per year; MS = mild steel;CU = copper alloy; SS =
Stainless Steel
494/16
-
TABLE VIEFFECTIVE MONITORING OF OZONE
EFECTIVENES:S REQUIRES:
. Detailed Water Analyses
. Rapid Corrosion Monitoring
. Deposition Monitoring
. Bio-Monitoring
. Ozone & ORP Analyses in SpecificLocations of System
. Equipment Inspection
494/1 7
-
L.a)mcm
%
ORIFICED
DECKDISTRIBUTION
+T5
&
OZONECONTACT
SUMP
(r,.2ii71
CIRCULATINGPUMPS(3) 3 3
f 1 (
cOliMON SUMP I
l?igureSCHEMATIC
OZONE
I Sample Line64 ft.+-om To II
MONITORING CHIL:;RS(3)STATION and
P&F HX
PLATE & F-
morn
lILLERSand
1&
TREATED SYSTEM
GENERATORHEAT EXCHMGERS(2)