1
Chemical Treatment Treatment of Cooling Water In Industrial Plants Basic Principals and Technology
By: Timothy Keister
Fellow, American American Institute of Chemists Certified Water Technologist
ProChemTech International, Inc. Brockway, Pennsylvania
Distribution: eneral TP !"#!
$ro%$ct%$a$er%TPCWT&! $ro%$ct%$a$er%TPCWT&!
!
I.
I!T"#D$CTI#!
'ue to the worldwide com$etitive nature of industrial activity today, all all industrial manufacturers must maintain strict control over various sources of $roduction cost& Cooling water is a commonly neglected area of the $roduction $rocess which is often res$onsi(le for su(stantial cost increases due to downtime, e)ui$ment damage, loss of $rocess control, and increased energy usage& *ther items which relate to treatment and control of cooling water+ such as water and sewerage costs, environmental regulations, and lack of sufficient fresh makeu$ water can also have su(stantial im$acts on all as$ects of manufacturing o$erations& -eglect of cooling water results results from two items+ first, the manufacturer often does not a$$reciate that cooling water is a vital $art of the $roduction $rocess and second, the fact that misinformation, .snake oil. $roducts, and marketing .hy$e. are common when cooling water treatment is the issue under discussion& This $a$er is intended to $rovide the industrial manufacturer with a (asic knowledge of $ro$er cooling water treatment so that $ro(lems resulting from corrosion, corrosion, scale, de$osition, and (iological fouling can (e avoided& /eduction of o$erating costs from increased efficiency in use of energy and control con trol of (oth makeu$ water and sewerage use will (e discussed, as well as avoidance of environmental $ro(lems and su$$lier selection& Any discussion of cooling water treatment must (egin with an o(0ective statement of what is e$ected from the cooling cooling water system& In manufacturing $lants, the cooling cooling water system must $rovide relia(le $roduction e)ui$ment cooling with maimum heat transfer efficiency& efficiency& The following four (asic re)uirements are derived from this o(0ective& %& 'inimi(e 'inimi(e problems problems from from corrosion corrosion,, scale, deposition deposition,, and gro)th gro)th to obtain ma*imum efficiency. +& Implementation Implementation and and control control must be do-able do-able )ith )ith a minimum minimum input input of labor and money. & Cost effecti/e effecti/e as possible considering considering the total total )ater )ater system system capital capital and operating costs. 0& 'ust be en/ir en/ironme onmental ntally ly accep acceptabl table. e.
These four re)uirements form the (asis for the following discussion of cooling water control and treatment&
#
II. W1T2" C32'I4T"5 C#!T"#6
*ne of the most interesting o(servations we have made over the years is that o$erational control of cooling water treatment $rograms is invaria(ly neglected and is thus the single most common cause of $rogram failure& The (est $ossi(le com(ination of corrosion, scale, and de$osition control chemicals, with effective (iocides, is com$letely worthless if not consistently and correctly a$$lied to the cooling water& Cycles Cooling water chemistry control (egins with cooling water cycles of concentration 7C& , or the num(er of times that the dissolved salts in the fresh ma8eup )ater 7'$& are concentrated (y eva$oration from the cooling system& This $arameter is commonly o(tained (y measuring the conductivity of the cooling )ater 7CW& and dividing it (y the measured conductivity of the makeu$ water& Please note that cycles can also (e calculated using other $arameters, such as chlorides and dissolved solids, which are common to (oth the makeu$ and cooling water and are not e$ected to (e effected in any great degree (y chemical additions or $reci$itations& C 2 CW conductivity"34 conductivity Control of cycles is critical in systems using non5softened makeu$ water as no chemical treatment $rogram can co$e with the increased $otential for scale formation resultant from ecessive levels of hardness salts in cooling water caused (y very high cycles o$eration& Why Cycle *ne )uestion that occasionally surfaces is .why use chemical treatments to o$erate at additional cycles when often no scale will form when o$erating at lower cycles.& The (est answer is that o$eration at increased cycles substantially lo)ers both the ma8eup and blo)do)n re9uirements , cutting the cost of fresh water and sewage dis$osal& With corrosive waters, increasing the cycles so that the water is rendered less corrosive is a .chea$. means to im$rove control of corrosion & Another $oint is that o$eration at increased cycles $ermits use of effective corrosion inhi(itors that may (e too co stly to em$loy at the higher (lowdown rates resultant from low cycle o$eration& Ty$ically, the most economical cycles to o$erate at is in the range of # to 6&
7
8nvironmental re)uirements and lack of sufficient fresh makeu$ water are n ewer forces driving cooling tower o$eration to higher cycles& We have recently seen cases where sewer ta$ fees for new $lants, measured in 91, amounts, were reduced to 91, sim$ly (y increasing cycles from # to 6& The environmental agencies are also taking a much closer look at $lant water use, one recent -P'8: $ermit issued in Pennsylvania contained a condition that the $ermittee reduce its water discharge (y ;<=, if economically feasi(le& Cycles 5 8conomics 'a*imum economic cycles is that cycles value where the total o$erating cost for the entire $rogram is lowest& This value has to (e determined (ased on the cost of water, (lowdown, and chemical treatment for each s$ecific a$$lication& *ne uni)ue set of o$erational $arameters consisting of cycles, inhi(itor chemistry, inhi(itor dosage, makeu$, and (lowdown can (e found for each makeu$ water"$lant com(ination that will give the lo)est total operating cost program & The first ste$ in selection of maimum economic cycles, and many times the (asic treatment $rogram, is to calculate the calcium car(onate saturation inde >:I? of the makeu$ water& The :I is utili@ed to ascertain if the makeu$ water is scaling >?, or non5 scaling >5?, $rior to cycling& The makeu$ water is then cycled, over a ty$ical range of ! to 1 cycles, and the resultant :I, makeu$ rate, (lowdown rate, inhi(itor chemistry needed, and chemical dosages calculated to determine the maimum economic cycles& These calculations can (e accom$lished totally (y hand calculator, or (y s$ecific com$uter $rograms& alue 0udgment is called for in selection of the inhi(itor chemistry and dosage& igher cycles reduce all costs, (ut also increase the potential for scale, corrosion, de$osition, and (iological fouling $ro(lems& The calculation of maimum economic cycles is com$le and can usually (e 0ustified only for larger $lants& In the ma0ority of cases, use of a chemistry that will $ermit # to 6 cycles o$eration will result in a total o$erating $rogram cost close to the desired minimum cost o$timum& :$ecific $roduct selection for control of scaling is then (ased u$on the :I at the selected cycles&
D
Cycles 5 Control Two methods have (een found to yield the (est control of cycles& The first, which is re)uired when makeu$ water chemistry varies su(stantially or the $lant has uncontrolled water losses, is to use an automatic control system (ased on measuring the conductivity >$ro$ortional to the level of dissolved salts in the water? of the cooling water& When the conductivity reaches the determined control level, an automatic valve is activated and high dissolved salt content water is drained from the cooling water system& /e$lacement of this drained water or blo)do)n 7BD& with fresh water lowers the conductivity of the cooling water, which causes the automatic valve to (e deactivated& Another means to control cycles automatically utili@es the makeu$ $ro$ortional method, where the amount of makeu$ water added to the cooling system is measured and a $ro$ortional amount of (lowdown drained from the system via o$eration of an automatic valve controlled (y a makeu$ water meter activated timer& Thus to o$erate at ten cycles, for every 1 gallons of makeu$ water added to the cooling water system, a$$roimately 1 gallons of (lowdown would have to (e drained& The e)uation for this is+ B' 2 34"C While this method is only a$$lica(le when the makeu$ water is of fairly consistent )uality and the $lant is low leakage, it is less costly to install and maintain than a conductivity (ased system and yields the same degree of control& An additional advantage is that there is no conductivity electrode which re)uires routine maintenance& As maintaining a set cycles value is the (asic control function in cooling water treatment, only high )uality, easy to maintain e)ui$ment should (e used so as to o(tain the most accurate, consistent, and relia(le control $ossi(le& Chemical Feed Control 3any methods have (een used over the years to control the addition of chemical inhi(itor $roducts to cooling systems& Common $ractices have included manual (atch feed timer controlled feed constant feed .feed"(leed., where chemical is in0ected simultaneously with (lowdown $ro$ortional feed and active control feed, where a relevant $arameter is measured and inhi(itor feed used to maintain a set $oint&
6
Critical evaluation of these various methods over the years has shown that the (est chemical inhi(itor control method is that using $ro$ortional feed& This is (ased u$on the fact that all chemical $roducts, with the ece$tion of (iocides, are dosed according to the amount of (lowdown from the cooling system, which is directly $ro$ortional to the amount of makeu$ added& Pro$ortional chemical feed systems are )uite sim$le, (eing (ased u$on metering the amount of makeu$ water added to the cooling water system and activating a chemical metering $um$ via a timer to add an amount of inhi(itor $ro$ortional to the amount of makeu$ added& As with control of cycles, only high )uality e)ui$ment which $rovides the (asic control function should (e used& The various .com$uteri@ed. and .on5line. control systems now (eing marketed have no technical advantage over the (asic control methods 0ust discussed& In fact, due to the increased com$leity of such systems, they are often less relia(le than (asic controls and are al)ays more e*pensi/e to purchase and maintain & While active control feed systems should have a technical advantage over $ro$ortional control systems, i&e& they are .measuring. the control $arameter in real time and maintaining control, in $ractice the systems on the market utili@e an easy to measure tracer compound added to the inhi(itor& :everal cases have (een documented where the tracer level has (een within control limits, (ut the actives in the inhi(itor were not due to selective $reci$itation and"or a(sor$tion within the cooling system& *ur comments concerning high cost and poor reliability a$$ly even more to this ty$e of control system at the $resent time& Calculation of Parameters Calculation of the various o$erating $arameters for a cooling system is very im$ortant as to initial si@ing and su(se)uent monitoring of control system $erformance& We have found the following e)uations to (e the most accurate for o(taining values for system e/aporation 72& , blo/do)n 7BD& , )indage 7W&, and ma8eup 7'$& as gal"day& 2/aporation is easily calculated (y+ 8 2 heat load (tu"hr >E? !7 hr"day &
<
3eat load 7& in (tu"hr can also (e determined (y the following e)uation if the cooling tower recirculation rate 7"& in g$m and delta T across the cooling5tower are known&
E 2 / 6 min"hr ;D l("gal delta F Blo)do)n is calculated using the eva$oration determined from the heat load on the cooling system with the following e)uation&
B 2 8 " maimum C 5 1 The maimum cycles value will (e set (ased u$on the determined lowest total o$erating cost for the water treatment $rogram as already discussed& Windage is commonly calculated using the following e)uation&
W 2 / 177 min"day &1 Please note that the windage factor varies from &1 to &D de$endent on the model and ty$e of cooling tower in use& Euality units (y BAC and 3arley are designed at a windage factor of &1, while most other units can (e calculated at &!& In normal systems windage can usually (e ignored for calculation $ur$oses, it is a ma0or factor only in high cycles and (ero discharge , systems with no intentional (lowdown& 'a8eup is sim$ly the sum of eva$oration, (lowdown, and windage, and can (e checked using mass (alance techni)ues&
328BW The measured cycles and makeu$ of a cooling system can (e used to determine the thermal load on a system (y using the a(ove e)uations& Com$arison of measured $arameters against calculated values should (e done on a routine (asis to ensure that cooling systems are within design limits and to locate .$ro(lems. in the system (efore they (ecome $roduction $ro(lems& Biocide Control The critical $oint concerning control of (iocide feed is to remem(er that the dose ma8es the poison, i&e&, there is a dosage >toic threshold? (elow which a (iocide will not work& :im$ly $ut, (iocides do not work unless a critical dosage is reached and maintained for a set time $eriod& The critical dosage $oint and time re)uired for effective micro(iological control varies su(stantially with the s$ecific (iocide in use and the overall condition of the cooling water system&
;
In addition to the critical dosage and time factor, one must also (e aware of the fact that microorganisms are very fast to ad0ust to such things as .toics. in their env ironment& 4se of many (iocides on a constant basis merely results in esta(lishment of a resistant flora in the cooling system (eing treated& These facts (eing noted, the (est method for addition of (iocide materials is on a slug, or intermittent, dosage (asis using the system volume to esta(lish initial dosage& :lug dosage can (e accom$lished either manually, or via automation using timers and $um$s& 8cellent results can (e o(tained (y either addition method, though safety considerations in handling of toic (iocides are increasing usage of the automatic feed systems & Garger cooling systems can o(tain su(stantial (iocide chemical cost reductions ( y using the recently develo$ed on5site chlorine dioide and hy$ochlorite"(romite solution generator"feed systems using either time (ased automatic feed or */P (ased controllers& The */P (ased controllers are actually one form of active control that has (een develo$ed to the $oint where it is relia(le enough for $lant usage& *$erator Attention While automatic systems for control of cycles, chemical feed, and (iocide addition will im$rove the $ro(a(ility for success of any cooling water treatment $rogram, a certain level of attention (y $lant o$erations $ersonnel is re)uired& :uch items as re$lacement of em$ty chemical drums and finding " re$air of water leaks can only (e done (y an o$erator& We recommend a daily check of the conductivity and makeu$ meter readings, along with a visual and o$erational check of the chemical feed $um$s and drums& Chemical tests of the cooling water should (e made and logged at least once a week (y the o$erator to ensure that $ro$er levels of treatment chemicals are (eing maintained in the cooling water& Garger $lants may (enefit from an increased amount of testing due to the $otential costs of u$sets& A technical re$resentative of the treatment chemical su$$lier should visit the $lant at least once a month to check o$eration of the automatic systems, undertake his own chemical tests >using his reagents? of the cooling water, and assist the $lant o$erator with resolution of any $ro(lems& We have found that service is usually (etter if the treatment chemical su$$lier has also su$$lied the chemical control and any $retreatment e)ui$ment used on the cooling water system&
H
While a lot of marketing .hy$e. is (eing e$ended u$on the telemetry and"or com$uter (ased controls now availa(le in the market, someone still has to go to the system to $rime the chemical $um$s, changeout the em$ty drum, or track down the leak& Trained o$erators and e$erienced service $ersonnel are still vital to o(taining good cooling water system o$eration and always will (e& III. C#""#4I#!
Water, while an ecellent trans$orter of heat and )uite ine$ensive, is also an ecellent ionic ty$e solvent which will dissolve more, or less, of 0ust a(out all known materials& iven this chemical fact, the chemistry of all cooling water treatment $rograms must (egin (y addressing corrosion, which is (asically an electrochemical oidation $rocess which results in destruction of the (asic metals from which most cooling systems are constructed& 4ncontrolled corrosion is often res$onsi(le for downtime from $hysical e)ui$ment failure, or $lugging of cooling water $assages from de$osition of corrosion $roducts& 3ore su(tle effects, often not linked to corrosion, are loss of $roduction s$eed and"or $rocess control and decreased energy efficiency, from de$osition of corrosion $roducts on heat transfer surfaces where the de$osit acts as an insulator to decrease thermal conductivity& Factors 3any factors effect the uncontrolled corrosion rates which could (e e$ected in a given cooling water system& :uch items as the $resence of dissolved gases, chloride and sulfate levels, $, alkalinity, scaling tendency, and $rotective ions such as $hos$hate and nitrate must all (e taken into consideration along with such engineering factors as water tem$eratures, $resence of galvanic cou$les, and water velocity in the design of corrosion control chemistry& A recently recogni@ed $ro(lem with new galvani@ed cooling towers con cerns .white rust., which is merely accelerated corrosion of the @inc coating of galvani@ed steel& The $ro(lem (ecame common when the lead content of the @inc used for galvani@ing was reduced due to en/ironmental restrictions , giving a much easier corroded @inc alloy& White rust has (een a more serious $ro(lem in cooling systems o$erated at $ values a(ove ;&! su&
1
The amount of white rust corrosion which occurs is directly proportional to (oth the total al8alinity and p3 of the cooling water, higher values of either $arameter result in an increased rate of corrosion& Control methods include $ control of the cooling water, reduced cycle o$eration, and use of s$ecific @inc corrosion inhi(itor chemistry& It is a fact that, in most cases, corrosion cannot (e eliminated, only minimi@ed or controlled to acce$ta(le rates& Test Control 3ethod The effectiveness of the corrosion inhi(itor $ortion of a cooling water treatment $rogram should (e monitored (y regular use of corrosion monitoring coupons to determine actual corrosion rates within the cooling water system& 8lectronic corrosion rate meters have (een develo$ed to the $oint where they are fairly accurate and )uite valua(le in many cases& Their ma0or $ro(lems are that they are su(stantially more costly than corrosion cou$ons and do not give long term rate data& While not as good as direct corrosion monitoring, a com$lete chemical analysis of the makeu$ and cooling water can often (e used (y a skilled technician to s$ot $ro(lems such as ecessive corrosion of co$$er alloys, or @inc, in the system& Corrosion rates a(ove those noted are cause for immediate remedial action& An acce$ta(le cooling water treatment $rogram should (e a(le to reduce corrosion rates to the following average levels re$orted as mil"yr+ 'ild 4teel 1luminum
% to + % to +
Copper 1lloys
;.% to ;.+ + to 0
Attainment of these control levels, which e)uate to a corrosion rate reduction of ;D= to HD= over uncontrolled level, can (e difficult due to the factors already noted& Inhi(itor Chemistry Purchasing agents have often (een )uoted as saying .all water treatment chemicals are the same, so we will (uy the chea$est ones&. This statement sums u$ some of the misinformation that a(ounds on water treatment chemistry& While it is true that most su$$liers have $roducts with similar chemistries and can du$licate each others $roducts, it is the a$$lication of s$ecific $roducts to a $articular $lant makeu$ water and cooling system design that differentiates success from failure&
11
3any s$ecific, and (lended, chemical inhi(itors are commonly utili@ed in cooling water treatment $rograms for control of corrosion& The following list notes some common inhi(itors with $ertinent comments& Chemical Chromate
Comments 8cellent steel corrosion inhi(itor, the standard against which all others are com$ared, banned by the $42P1 for environmental reasons& ood su$$lemental inhi(itor at 1 to ! mg"l level, some PA? for steel at D to 1D mg"l, (est results o(tained with a minimum of D mg"l calcium $resent&
1!
Pro$rietary inhi(itor for control of white rust corrosion at ! to 6 mg"l
3ost successful cooling waterKtreatment $rograms utili@e several chemical inhi(itors (lended into one $roduct to take advantage of a synergistic effect where the net reduction in corrosion from use of the miture is greater than the sum o(tained from individual com$onents& For eam$le, adding ! mg"l of @inc to an PA $roduct at 1!&D mg"l reduced the corrosion rate on mild steel from !&! mils"yr to &H mils"yr& 'ue to this effect, it is common to see $rograms using mitures such as moly(date5silicate5a@ole5$olydiol, $hos$honate5$hos$hate5a@ole, and moly(date5$hos$honate5$olydiol5a@ole& For $lants where the cooling water system is constructed of several materials, which would include almost all industrial facilities, a $rogram using a (lended corrosion inhi(itor $roduct is re9uired to o(tain satisfactory corrosion $rotection& The eact inhi(itor chemistry must (e determined (y the water treatment $rogram su$$ lier following an evaluation of makeu$ water chemistry, system materials of construction, and o$erating conditions& :oft Water -ote In cooling systems o$erated using naturally soft, or softened, makeu$ water, control of corrosion is the ma0or challenge for the water treatment $rogram& The common )ater treatment industry practice of using makeu$ water hardness and alkalinity to $rovide the (ulk of corrosion control action does not )or8 with these ty$es of makeu$ water& In fact, the most commonly used corrosion inhi(itors, $hos$hates and $hos$honates, do not work if less than D mg"l calcium hardness is $resent in the cycled cooling water& This often overlooked fact has (een res$onsi(le for many documented $ro(lems where this chemistry was a$$lied to soft water makeu$ systems with horri(le results& As soft water makeu$ can (e used to achieve @ero discharge for water use reduction or environmental reasons, this s$ecific $ro(lem will (ecome more common& 3any schemes for reuse"recycle of treated industrial wastewaters, $articularly in the electronics industry, will $rovide a soft water for use as cooling tower makeu$& Plants using soft waters as cooling system makeu$ are advised to guard against this misuse of technology and utili@e a water treatment $rogram su$$lier who has demonstrated knowledge in the use of soft water makeu$&
1#
The use of softening to render a hard water source suita(le for use as cooling tower makeu$ should (e evaluated very carefully as to the $otential for increasing .white rust. corrosion of new galvani@ed steel com$onents& 'ue to the normally high level of alkalinity associated with hard waters, softening may accelerate white rust corrosion (y factors eceeding 1 times& We recently ins$ected a new softened makeu$ cooling tower system and found that over D= of the galvani@ing had (een removed from the cooling tower in less than thirty >#? days& I=. 4C162
'e$osition of scale is a chemical $reci$itation $rocess where dissolved salts in the cooling water .out. surfaces in contact with the water due to their solu(ility limits (eing eceeded& The most common scale formers, calcium salts, ehi(it reverse solu(ility in that they (ecome less solu(le as the tem$erature of the water increases& This $ro$erty causes scale formation in the most sensitive area, the heat transfer surfaces of $roduction e)ui$ment& :ince the thermal conductivity of scale is su(stantially less than metal, heat removal from the e)ui$ment is reduced and $roduction s$eeds must (e lowered to com$ensate& In etreme cases, enough material $reci$itates to $hysically (lock the cooling water $assages, resulting in the effected e)ui$ment (eing removed from $roduction for either chemical >acid? or mechanical cleaning& :cale formation on the condensers of freon cycle chillers reduces the efficiency of these units for removal of heat from chilled water systems, thus increasing the $ower needed to o(tain a given volume of chilled water& arious studies have shown a non5linear electrical $ower cost increase with increased scale thickness, for instance &D mils of calcium scale results in a $ower cost increase of #&D=, while 1&D mils increases $ower cost to a$$roimately 1!&D=& Control :cale can (e controlled, or eliminated, (y a$$lication of one, or more, $roven techni)ues& Ty$ical measures taken to control scale start (y controlling cycles followed with chemical scale inhi(itor treatment, $ ad0ustment (y acid addition, or softening of cooling water system makeu$&
17
As noted, cycles are (est controlled (y installation of a high )uality system for automatic (lowdown (ased on conductivity or metered makeu$& Chemical scale inhi(itors function (y either selective adsor$tion on growing scale crystals, converting the crystal structure into a non5scaling ty$e which does not form a hard scale, or chemical reaction with the scale forming ions, converting them into non5scale forming materials& The following list notes some of the chemical scale inhi(itors commonly encountered& Chemical Polyacrylate
>mw 2 !? Polymetbacrylate Polymaleic 4ulfonated polystyrene Phosphonates Chelants
Dipolymers
Terpolymers
Polyphosphates
Comments Commonly used, cost effective for calcium scale at D to 1D mg"l&
Gess common for calcium scale at D to 1D mg"l& ery effective for calcium scales at 1 to !D mg"l, costly& 8ffective calcium inhi(itor, less sensitive to iron levels, commonly used at levels of 1 to ! mg"l& All three common $hos$honates are ecellent calcium scale inhi(itors at levels from D to ! mg"l& Both 8'TA and -TA, as well as citric acid and gluconate, have seen some limited use for calcium scale control at levels from D to 1 mg"l& These $roducts commonly incor$orate two active grou$s, such as sufonate and car(oylate, to $rovide su$erior $erformance to a single grou$ com$ound& 4se levels at D to ! mg"l& Gike the di$olymers, only incor$orate three active grou$s to give yet (etter $erformance under severe conditions& 4se levels at D to ! mg"l, costly& Fairly good calcium scale control under mild conditions, can revert and contri(ute to calcium $hos$hate scale&
As with corrosion inhi(itors, mitures of scale control chemicals have (een found to generally $rovide su$erior $erformance to single com$onent $roducts& Thus most formulated $roducts will often contain two, or more, materials, ty$ical formulations usually contain one, or more, $hos$honates com(ined with $olyacrylate&
1D
As a general rule, ty$ical chemical scale inhi(itors can (e utili@ed if the 6angelier 4aturation Inde* 74I& value of the cycled cooling water does not e*ceed +.; & Cycled cooling water :I values eceeding !& normally re)uire use of eotic chemistries, $ ad0ustment (y acid addition, or makeu$ water softening& *ur firm, as well as some others, has re$orted o$eration of cooling systems, with newer treatment chemistries, scale free at cycled :I values from !&; to #&D without $ ad0ustment& $ Ad0ustment Control of scale with $ ad0ustment (y acid addition functions via chemical conversion of the scale forming materials to more solu(le forms& Thus, calcium car(onate is converted to calcium sulfate >using sulfuric acid for $ ad0ustment?, a material several times more solu(le& -ormally, it is not desira(le to add sufficient acid to convert all of the scale forming materials due to a su(stantial increase in the corrosivity of the cooling water if this is accom$lished& *f course, addition of ecessive acid to the cooling water results in de$ressed $ values and etremely ra$id corrosion of all system metals& The :I and another inde, the /y@nar :aturation Inde >/:I?, are utili@ed for system setu$ when $ ad0ustment (y acid addition is used for scale control& Both indees are merely convenient means of reducing the integrated $arameters of calcium, alkalinity, $, dissolved solids, and tem$erature to a single value, which indicates the tendency of water to form a calcium scale or $romote corrosion& Thus,, a $ositive :I num(er >/:I less than D&? indicates a scale forming water, while a negative :I num(er >/:I greater than <&? indicates a scale dissolving, or corrosive, water& :I can (e easily calculated as follows with a hand calculator+ -ormal $ractice is to maintain a slightly $ositive :I num(er, &! to &D, >/:I (etween D& and 6&? when utili@ing $ ad0ustment (y acid addition and add some chemical scale inhi(itor to co$e with the resultant slight tendency to scale& Instances have (een re$orted where scale has (een controlled with makeu$ calcium water hardness values u$ to # mg"l as CaC*# with a com(ination of $ ad0ustment (y acid addition and chemical scale inhi(itors&
16
:I Calculation 4sing a standard water analysis, the :I can (e easily calculated using the following e)uations with a hand calculator& Gogs are (ase 1, analysis results in mg"l& 1& PI 2 Gog >calcium !&D total alkalinity? !& 'etermine the highest e$ected water tem$erature >F? in the cooling system and use it as follows+ P! 2 >>F? &H1!? PI #& P# 2 >>Gog >T':?? &1? 1!&!< 7& $ saturation 2 P# 5 P! D& :aturation Inde >:I? 2 $ water 5 $ saturation -otes+ Conductivity &; can su(stitute for T': An im$ortant $oint to remem(er is that acid addition to cooling water should only (e undertaken with an automatic p3 control system and )ell trained operators & This caution is included as serious corrosion damage will occur in a short $eriod of time if ecessive acid is added to the cooling water& *nly high )uality $ controllers e)ui$$ed with acid $um$ lockout timers should (e considered for this critical a$$lication& 'aily $lant control testing is re)uired with use of $ control systems& While not yet common usage, scale can (e com$letely eliminated (y softening all cooling system makeu$ water& It has (een our e$erience that using softened makeu$ water for scale control is the safest, most cost effective method availa(le& -ormally, the added cost of softened makeu$ water is (alanced (y the decreased chemical and water usage resultant from the increased cooling system cycles made $ossi(le (y the soft water& The increased general corrosiveness of the softened water is countered (y the high $ values >;&D to H&D? develo$ed when the cooling system is cycled u$ with softened makeu$& This, in com(ination with a good chemical corrosion inhi(itor $rogram, usually results in lower corrosion rates than the same cooling system using c hemical scale inhi(itors or $ control (y acid addition& !ote that s$ecific inhi(itor technology for control of )hite rust must (e utili@ed with softened makeu$ water&
1<
4se of softened makeu$ water is also em$loyed to o(tain @ero (lowdown discharge from cooling systems for either fresh water use reduction or environmental reasons& /eference to the e)uations given in :ection II show that @ero discharge can (e attained if windage e)uals or eceeds (lowdown& Thus, an increase in cycles to reduce (lowdown to the $oint where it is e)ualled, or eceeded, (y windage will result in @ero li)uid discharge from the cooling system& In $ractice, @ero (lowdown is attained (etween fifteen and thirty cycles with conductivities of u$ to 6, mmhos re$orted& Facilities attem$ting to attain @ero discharge are advised to use a water management firm which has e$erience in this area due to the increased $otential for corrosion when using softened makeu$ water, control of white rust, and $ossi(le increased de$osition from the high cycles re)uired& =. D2P#4ITI#!
'e$osition is a general term for all the things that can cause $ro(lems in a cooling water system that are -*T due to scale, corrosion, or (iological activity& We find that such de$osition can result from scru((ing of air(orne material from the a m(ient air (y the cooling tower, $rocess contamination of cooling water (y such things as leaking oil coolers, and sus$ended material in the makeu$ water& 'e$osition effects $rocess o$erations much like scale, the de$osits act as a thermal insulator to decrease heat transfer efficiency in $roduction e)ui$ment& 'e$osition can also cause $hysical (lockage of cooling water $assages and increase corrosion rates (y (locking corrosion inhi(itor access to the (ase metal, i&e&, under de$osit corrosion& Control 3easures taken to control de$osition de$end on the cause of the $ro(lem& Process contamination $ro(lems are (est corrected (y elimination of the $rocess leakage, while most sus$ended solids de$osition can (e controlled (y addition of dis$ersant"surfactant chemicals to the cooling water& These materials function (y charge neutrali@ation of the sus$ended $articles and emulsifying (inding agents, (reaking u$ eisting de$osits and $reventing agglomeration of the $articles to form new de$osits&
1;
The following list notes some of the dis$ersant"surfactant chemicals commonly encountered with comments+ Chemical Polyacrylate
>mw LD? Polymethacrylate Polymaleic 4ulfonated polystyrene Dipolymers
Terpolymers
Polydiol 2tbo*ylates 4ulfonates
Comments Commonly used, cost effective for clays and silts at D to 1D mg"l&
Gess common for clays and silts at D to 1D mg"l& ery effective for clays, silts, and iron (ased de$osits at 1 to !D mg"l, costly& 8ffective de$osition inhi(itor, less sensitive to iron levels, commonly used at levels of 1 to ! mg"l& These $roducts commonly incor$orate two active grou$s, such as a sulfonate and car(oylate, to $rovide su$erior $erformance to a single grou$ com$ound& 4se levels at D to ! mg"l& Gike the di$olymers, only incor$orate three active grou$s to give yet (etter $erformance under severe conditions& 4se levels at D to ! mg"l, costly& :urfactant action (reaks u$ many de$osits at ! to 1 mg"l& :$ecific surfactants used to (reak u$ oily de$osition at 1 to < mg"l& eneral surfactants used to (reak u$ many ty$es of de$osits
:evere sus$ended solids de$osition should (e treated with a com(ination of chemical dis$ersants"surfactants and an element filter, hydrocyclone, or media filter, in a side stream configuration& 'ue to @ero ecess water loss o$eration, and lower cost, a hydrocyclone set u$ to discharge via system (lowdown is oftentimes $referred over a media filter& 8lement filters, using reusa(le (ags or cartridges, are finding increasing a$$lication in @ero discharge cooling systems where (lowdown must (e eliminated for either water use reduction or environmental reasons& We have found that if a cooling system is to (e o$erated at over si >6? cycles, some form of (y$ass filtration is re)uired to $revent de$osition and resultant under de$osit corrosion $ro(lems& In dusty environments, such of (y$ass filtration may (e re)uired, regardless of the chemistry or cycles o$erated at&
1H
=I. BI#6#IC16 >#$6I!
3icro(iological growth within a cooling water system, if not controlled, can result in formation of (iological fouling layers on all surfaces in contact with the cooling water& The (iological fouling effects $rocess o$eration much like the $reviously discussed scale and de$osition, the (iological fouling acting as a thermal insulator to decrease heat transfer efficiency in the $roduction e)ui$ment& Biological fouling usually results in su(stantial corrosion rate increases due to formation of anaero(ic areas under the fouling layer, which creates galvanic cou$le corrosion, and formation of meta(olic (y$roducts, such as hydrogen sulfide, which actually attack the (ase metals& :evere cases of (iological fouling have resulted in com$lete cooling system failure due to the (iomass $hysically $lugging cooling water $assages in $roduction e)ui$ment and cooling towers& Water(orne diseases, such as 6egionnaire?s Disease , are also a ma0or health and safety concern with o$eration of many cooling water systems& :ystems which are not maintained in a clean and (iologically controlled state can often (e sources of such infections, which can sicken, or even kill, e$osed em$loyees& Chemistry Present $ractice for control of (iological fouling is to $eriodically dose the cooling system with a (iocide to kill as many of the organisms $resent as $ossi(le& Again, the critical $oint concerning control of (iological fouling is to remem(er that the dose ma8es the poison& sim$ly $ut, a (iocide will not work unless a critical dosage is reached and maintained for a set time $eriod& The critical dosage $oint and time re)uired for effective micro(iological control varies su(stantially with the s$ecific (iocide in use and the overall condition of the cooling water system& The (iocides commonly used can (e (roadly (roken into two ma0or classes, oidi@ing and non5oidi@ing *idi@ing (iocides function (y chemical oidation of the cellular structure of the organism, which effectively destroys it and kills the organism& 'ue to the destructive form of attack, it is impossible for any organism to sho), or de/elop, significant immunity to an o*idi(ing biocide & *idi@ing (iocides are usually )uite cost effective due to their low unit cost, ra$id effect on the target organism, and low effective dosage&
!
4nfortunately, oidi@ing (iocides do have some draw(acks& 5 :ome can decrease coolingMwater $ in a uncontrolled manner >gas chlorine and chlorine dioide generators?& 5 3ost increase the corrosive nature of the cooling water& 5 :ome, such as chlorine, $roduce undesira(le (y $roducts from an environmental stand$oint& 5 Corrosion and scale control chemicals can (e inactivated (y contact with s$ecific oidi@ers& 5 -one of the oidi@ing (iocides have any dis$ersant effect for removal of dead micro(iological growth and"or $enetration of organic slime layers& 5 Process contamination can neutrali@e many oidi@ers& 5 :ome oidi@ers are sensitive to water $ as to effectiveness& The following list notes some common oidi@ing (iocides and our comments+ Chemical Bromochlorodimethylhydrantoin
Chlorine dio*ide
Chlorine
#(one
6i9uid and solid chlorines
3ypochlorite@3ypobromite
Comments ery effective $roduct at 1! to #6 mg"l $roduct, costly for an oidi@er on a $er $ound (asis, safe to use 8tremely effective $roduct at &D to ! mg"l active, must (e generated on5site from reactive ingredients, lowers system $, contact measured in minutes, few environmental $ro(lems, some safety $ro(lems The .old. stand(y and still most cost effective $roduct availa(le at levels of &D to 1& mg"l& Pro(lems include :A/A Title III status, danger of working with $ressuri@ed gas, and lowering of system $& :ome environmental $ro(lems with chlorinated hydrocar(ons noted& ery effective (iocide, ma0or $ro(lem is cost and maintenance of on5site generator and $ure air needed& *@one emissions from cooling tower may create a first class environmental $ro(lem& 4sually cost effective, (ut increase system $ values, white rust and >hy$ochlorites? corrosion& :ome solid $roducts add calcium to system& /ecently introduced technology that generates active oidi@ers on5site using electrolysis of neutral salts& 3ay (e the (est choice from the stand$oints of safety and effectiveness&
!1
The recent introduction of on5site generator"feed systems for chlorine dioide, hy$ochlorite, and hy$o(romite eliminates some of the $ro(lems with oidi@ing (iocides and have (een demonstrated to (e an effective and safe means to attain good (iological fouling control& 4nfortunately, the ca$ital cost of these installations can only (e 0ustified for larger or $ro(lem cooling systems& -on5oidi@ing (iocides function (y interference with the meta(olism of the organism in a variety of ways, which (y $reventing normal $rocesses, kills the organism& 'ue to the large variety of organisms, those that are immune to a $articular non5 o idi@ing (iocide will ra$idly re$lace those that are killed (y a single dosage& Following doses will (ecome $rogressively less effective as the organism $o$ulation shifts to those varieties that are immune to the $articular (iocide em$loyed& 'ue to this natural effect, it is recommended that at least two different non5oidi@ing (iocides, or a oidi@ing and a non5oidi@ing (iocide, (e utili@ed in (iological control $rograms on an alternating (asis& -on5oidi@ing (iocides can (e )uite costly due to the high effective dosage re)uired with some $roducts, long contact times re)uired with some $roducts, and their often high unit cost& -on5oidi@ing (iocides do have advantages in that most function in the $resence of $rocess contamination, no effect on corrosivity is evident from their use, corrosion and scale control chemicals are usually not effected (y them, often they can (e targeted at a s$ecific class of $ro(lem organism, and several have a definite dis$ersant effect for removal of dead micro(iological growth& The following list notes some of the non5oidi@ing (iocides, and our comments, commonly encountered& Comments Chemical 3ydro*ymethyl nitro propanediol 8ffective only with a long residence time dosage of < to 17 mg"l as $roduct needed& >Trisnitro? Product effective at 1D to H mg"l, (ut only at $ 'ethylene bisthiocyanate values lower than <&; >3BT? 8ffective against (acteria and algae at !D to 6 uats and Poly9uats mg"l, high foamers, inactivated (y oil"grease, high hardness& enerally low cost&
!!
uat-bistributyl tin
>Euat"tin? Carbamates
Isothia(olin
>I:*? lutaraldehyde
>lut? Dibromo nitrilo propionamide
Euite effective against most (iology, foams and can (e deactivated (y oil"grease and high calcium& Potential environmental $ro(lems due to $ersistence of tin com$onent& 'osage levels of 7 to 1 mg"l& ery effective at dosages from 7 to 6 mg"l against most everything, ecellent against algae& /ather toic to em$loyees and environment, can cause $reci$itation $ro(lems with metals in solution& 3oderately effective against everything (ut algae at levels of #D to ! $$m& ery dangerous for em$loyees to handle due to attack of eye structure& 4sually costly due to dosage and $roduct cost& enerally effective (iocide with ma0or draw(ack (eing high dosage of 1# to 66 mg"l needed for effective control& 4sually most costly $roduct due to high dosage and $roduct cost& enerally effective (iocide, higher dosage needed for algae, dosages of ! to ; mg"l, $ values (etween 6& and H&D, fast acting&
>'B-PA? Ty$ical $ractice for successful cooling water treatment will em$loy (oth an oidi@ing and non5oidi@ing (iocide, with usage alternated on a weekly, or (iweekly, (asis& Thus a ty$ical com(ination would (e to dose chlorine dioide twice a week, with car(amate as an alternative every other week& The cost for non5oidi@ing (iocides varies su(stantially on a $roduct (asis, with actual use cost com$licated (y the )idely /arying dosages of the various $roducts, thus making cost com$arisons difficult&
!#
We have calculated the following generic $roduct use cost, calculated as 9 to treat 1 gallons of cooling water, (ased on using the recommended dosages and list $rices for the various (iocides su$$lied (y our com$any& Product != $oly)uat 1= )uat #= car(amate != )uat"tin 1= 3BT 1!&D= )uat"tin 1D= glut N oidi@ers for com$arison
Cost 9&
Product D= $oly)uat H!&D= hydantoinN != 'B-PA !D= trisnitro D= trisnitro 1&D= iso chlorine dioideN
Cost 9&71 &<< 1 1&; 1&7 #&6# &D
*n review of this chart, we were shocked (y the use costs for glut and iso, which are commonly s$ecified for use in many industrial systems& -ote should also (e made concerning several .all in one. $roducts which $ackage a non5 oidi@ing (iocide with an inhi(itor chemistry for control of corrosion, scale, and de$osition in one drum& *ur e$erience has (een that these $roducts are almost worthless for effective control of (iological fouling due to the ina(ility to alternate (iocides, ad0ust (iocide dosage inde$endent of the other inhi(itors, and the $articular chemistry of the (iocide mandated (y the other com$onents in the $roduct& Control Control of (iocide feed is somewhat su(0ective in that a visual determination of micro(iological growth is generally used to determine if the ( iocide $rogram is effective& Porta(le .di$ stick. indicators to test organism density are availa(le and will likely (e utili@ed more in the future& At $resent, a good starting $oint is to determine the actual volume of the cooling system (y the lithium salt dilution techni)ue and use the su$$liersK suggested dosage& The dosage can then (e ad0usted (ased on the o(served results and .di$ stick. testing& *ur guidelines, as well as the C'C, are to maintain test results no greater than l87& alues a(ove this re)uire increased dosage levels"more fre)uent a$$lications of (iocides& Continued high readings indicate that a switch in (iocide chemistry is re)uired& GegionnaireKs 'isease is controlled in cooling systems (y maintaining a (iologically clean system, which is defined (y the C'C as having no visi(le (iological de(ris in the system and having total $late counts (elow l87&
!7
If it is not $ossi(le to determine the actual system volume, we have found that the following .rules of thum(. give good starting $oint volumes& :tandard cooling tower systems
1D gallons"ton
8va$orative condenser systems
! gallons"ton
=II. C32'IC16 P"#"1' 4262CTI#! While the chemistries of makeu$ waters are almost unlimited, a few generali@ations can (e made concerning classes of makeu$ water and the s$ecific treatment chemistries which have (een found to (e most effective&
A& -atural low alkalinity, low hardness waters with :I less than 51& are found in some areas of the country and, like softened waters, are normally very corrosive& 3any of the treated industrial wastewaters (eing considered for reuse as cooling tower makeu$ fit within this classification& These waters were formerly treated successfully using $rograms (ased on the now environmentally outlawed high chromate5@inc chemistry& They are now (est treated (y using a (lended $roduct containing at least two good inorganic corrosion inhi(itors, such as silicate, @inc, or moly(date an organic inhi(itor such as $olydiol and an a@ole for yellow metal $rotection& A dis$ersant to control de$osition and some $hos$honate to control de$osition of $roducts of corrosion will com$lete the $rogram& In most cases, all of the a(ove chemistry can (e (lended into a single $roduct& B& 3akeu$ waters with alkalinity and calcium hardness values (etween D and ! mg"l, :I 51& to 1&, are commonly found throughout the country& These waters $ermit a much wider selection of water treatment chemistries, which are all ca$a(le of giving acce$ta(le $erformance with $ro$er selection and control& The following chemistries are generally a$$lica(le to these waters+ 1& The classic water treatment chemistry for this ty$e of water was to con trol scale formation (y $ ad0ustment, using a high chromate5@inc, sometimes with $hos$hate, chemistry to very effectively control corrosion& 'is$ersants were added to the later formulations to control de$osition& While $rograms (ased on this chemistry are very effective and economical, they have (een (asically outlawed (y environmental regulations&
!D
!& Programs which use only $hos$honate and $olymer chemistry to control scale formation, commonly referred to as .all organic. have (een introduced and used with good results& :cale is handled as noted, while corrosion is controlled (y formation of a layer of a(sor(ed calcium"iron $hos$honate on the metal surfaces, and develo$ed hardness and alkalinity& The (etter $rograms also include a@ole for yellow metal $rotection and may have additional dis$ersants for (etter de$osition control& 3oly(date at levels of 7 to 6 mg"l is often added as an easy to test for tracer and additional $itting corrosion control& #& Phos$hate inhi(itor chemistry using $ ad0ustment to maintai the cooling water in a non5$hos$hate scale forming region >usually <& to <&D su? has (een used as a low cost $rogram which can give good results& This ty$e of $rogram de$ends u$on $ ad0ustment to control scale, while high levels of ortho $hos$hate, 6 to 1! mg"l, are used to control steel corrosion& 4se of an a@ole for yellow metal $rotection is a good idea, as well as inclusion of a dis$ersant and $olymer to assist in control of (oth de$osition and scale& 7& Alkaline $hos$hate, or sta(ili@ed $hos$hate, $rograms de$end u$on $hos$honates and advanced $olymer chemistry to control scale formation without $ ad0ustment& Corrosion is controlled (y the ortho $hos$hate, high develo$ed alkalinities, and de$osition of a controlled layer of calcium $hos$honate"calcium $hos$hate on steel surfaces& 4se of an a@ole for $rotection of yellow metal surfaces is re)uired, while additional dis$ersants may, or may not, (e needed de$endent on which $olymer>s? are in use& 3oly(date has (een added to some $rograms as (asically a tracer for control testing and for added control of $itting corrosion& D& *ur firm has develo$ed an additional chemistry, T/APtm, (ased on $hos$hinocar(oylate, $olydiol, and advanced $olymer chemistry, which allows much higher cycles to (e o(tained with such makeu$ waters& :cale is controlled (y the se)uestrant 5 dis$ersant action of the chemistry, while corrosion is controlled (y the very high develo$ed alkalinity and formation of organic $olydiol films on metal surfaces& :everal s$ecific $roducts have moly(date incor$orated in the formula for control testing and additional $itting corrosion control& This ty$e of $rogram is not yet in common use due to its high chemical cost a$$lications to date have (een restricted to water short areas, very hard waters, or @ero discharge systems&
!6
In all of the a(ove $rograms, @inc can (e added as a su$$lemental corrosion inhi(itor, (ut use of this metal is under increasing environmental $ressure& At least two organic corrosion inhi(itors, $olydiol and hydroy $hos$honocar(oylate, are also (eing used to $rovide additional corrosion $rotection& C& 3akeu$ waters with calcium hardness and alkalinities over # mg"l and giving :I values eceeding !&D, at only ! to # cycles, are less common, (ut are coming into increased use in some $arts of the country due to water shortages& Three $roven chemistries are availa(le to treat this ty$e of makeu$ water+ $ ad0ustment with use of either organic or $hos$hate inhi(itors, softened makeu$ with use of good inhi(itors, or T/APtm chemistry& Control of scale with cycled :I values eceeding #& and calcium hardness values eceeding ! mg"l has (een demonstrated with T/APtm chemistries& The use of softened makeu$ water has $roven to (e very successful with these hard waters& Corrosion is routinely controlled to levels of I mil"yr or less on mild steel, while $rogram cost is e)ual to, or less, than other $rograms, with no scale formation& :oftened makeu$ is also re)uired for o(taining @ero discharge with most waters& The high cycles re)uired for (alancing (lowdown against windage cannot (e o(tained without scale formation unless the makeu$ water is softened& =III. 4$PP6I2" 4262CTI#!
While the foregoing $rovides the industrial manufacturer with the (asics for $ro$er cooling water treatment, the actual chemistry of the $rogram is in the hands of the su$$lier selected (y the facility& It is thus im$ortant that a knowledgea(le su$$lier (e selected who can $rovide a$$ro$riate control systems and chemistry tailored to the $lant cooling systems and makeu$ water )uality& The following are some comments on the selection of a water management $rogram su$$lier& Business The su$$lier selected should (e in the industrial water treatment (usiness and deal on a routine, direct (asis with various industrial manufacturing $lants& There are many firms in the market, in $articular $roduct distri(utors and AC contractors, that deal in such things as floor cleaners, solvents, oils, AC e)ui$ment"maintenance, or water softeners who would also (e ha$$y to sell a few drums of cooling water treatment OBrand to anyone&
!<
*ur e$erience has (een that these firms have a very limited $roduct line, no e$ertise in actual water treatment chemistry, little or no control system e$ertise, and no analytical la(oratory su$$ort for resolution of any cooling water treatment $ro(lems which a$$ear& We also have a decided $reference for firms which manufacture their own chemical $roducts& While there are many successful com$anies which utili@e .toll (lenders., our own e$erience indicates that $roduct )uality cannot (e ade)uately controlled with outside $roduct manufacture& Comments that .the chemicals are all the same. are o(viously incorrect to anyone who has some knowledge of the water treatment field& A $roduct that would $rovide ecellent results with a hard, alkaline makeu$ will $rovide noting (ut high corrosion rates and early system failure if used with a soft, low alkalinity water& Pro$er selection of the s$ecific chemistry and $roduct formulation to (e used in any cooling water system should (e under the su$ervision of an e$erienced water treatment chemist& The AWT OCertified Water Technologist >CWT? $rogram, $ut in $lace a(out four years ago and o$en to anyone in the water treatment industry, is the one means of esta(lishing the needed e$ertise in this field& 8nvironmental 8$ertise in environmental regulations and water conservation is also (ecoming a ma0or consideration in selection of a water management $rogram su$$lier& The su$$lier should have the ca$a(ility to consider the effect of environmental regulations on the s$ecific chemistry to (e used, and $rovide any information needed (y the regulatory authorities& While the returna(le (ulk containers (eing .$ushed. (y several of the large firms in the water treatment industry for avoiding container dis$osal $ro(lems sound goo d, they do $resent some $ro(lems of their own& The increased cost of the (ulk container, as com$ared to the standard drum, usually results in a higher cost for $roducts delivered in this mode as com$ared to drum $rices& A ma0or environmental consideration is the $otential for environmentally damaging s$ills& Goss of ! to #D gallons from a (ulk container is several times more damaging than a loss of DD gallons from a drum& As an eam$le, note that :A/A re$orting limits, (eing (ased on the amount of material s$illed, may often (e triggered (y a (ulk s$ill, and not (y a drum s$ill&
!;
We would recommend that the container dis$osal issue (e sim$ly and economically addressed (y using a su$$lier that will sim$ly acce$t return of all em$ty $roduct containers, from five gallon $ails right through (ulk containers& This $ermits the most economical $ackaging to (e selected from (oth the usage and cost stand$oints, avoiding a lot of the .marketing hy$e. for which the water treatment industry is known& /eturn of all em$ty containers totally eliminates any container dis$osal $ro(lem and im$roves the environment (y recycle of the $ackaging& From a stand$oint of water conservation, the su$$lier should have s$ecific in de$th knowledge of (lowdown reduction and @ero discharge technologies& As noted, this is a s$eciali@ed area and few su$$liers have yet develo$ed the e$ertise, e)ui$ment, and chemistries needed to $rovide cost effective $rograms& The (est means of o(taining a firm with e$ertise in this field is to note any technical $resentations made (y the firm and references as to com$leted $ro0ects& 8$erience is the (est means to ensure )uality work in this new, and ra$idly evolving $art of the water treatment field& Gocal :ervice The local service re$resentative of the su$$lier is also very im$ortant to the success, or failure, of any water treatment $rogram due to intimate involvement in chemistry s$ecification, $rogram control, and trou(leshooting& The user is advised to carefully screen the su$$lier re$resentatives and o(tain one who has (oth a technical (ackground and e$erience in the cooling water treatment field as a$$lied to industrial $lants& IA. 4!1K2 #I6
In many ways the industrial water treatment resem(les the used car market& While there are many re$uta(le com$anies that maintain high $rofessional standards and will do an ecellent 0o( in most cases, there are also many .snake oil. firms that sell technologies that are (asically worthless or not a$$ro$riate& 8am$les of such items are the many .magnetic., .electronic., and .catalytic. water treatment devices that have (een sold for the $ast sity years& *(0ective testing has never found a single such device to $erform as advertised& An ecellent eam$le of a technology that has (een sold for ina$$ro$riate uses is o@one& :everal firms have claimed that o@one can (e used to control corrosion, scale, and de$osition as well as its esta(lished use as an ecellent oidi@ing (iocide& Again, o(0ective testing has $roven that o@one is (asically ineffective as a corrosion, scale, and de$osition control agent&
!H
A. 4$''1"5
Poor cooling water treatment and control increases $roduction costs in industrial manufacturing $lants& :election of a cooling water treatment $rogram and su$$lier (ased on some knowledge of the chemistry and control needed will increase the $ro(a(ility of o(taining relia(le $roduction e)ui$ment cooling with maimum heat transfer efficiency at the lowest total cost& Those facilities who devote sufficient time and resources to this vital area of their $rocess will (e rewarded (y lowered $roduction costs and a com$etitive edge& Qnowledge of the field will also ena(le the (uyer to se$arate .snake oil. $roducts from valid technologies and guard against the $ro(lems that can result from use of such something for nothing $roducts&
Timothy Qeister 5 olds a B&:c& in Ceramic :cience, Fellow of the American Institute of Chemists, and is a Certified Water Technologist& e has (een the Chief Chemist of ProChemTech since founding the firm in 1H;<& Prior to this, he s$ent 1# years as :ection ead, Water"Wastewater Control, for Brockway lass Com$any, a Fortune D manufacturing com$any& e has $resented and written numerous articles on water and wastewater chemistry, water reuse"recycle, water and wastewater treatment, and su$$lier selection& ProChemTech International was founded in 1H;< to $rovide industry with )uality chemical $roducts, control e)ui$ment, system design, and the $rofessional technical su$$ort needed to o$erate industrial water systems in the most cost effective, environmentally safe manner $ossi(le& The com$any is organi@ed as a .sole source. su$$lier, utili@ing its ca$a(ilities in s$ecialty chemical and e)ui$ment manufacture, systems design, research, environmental services, analytical services, and engineering to devise com$lete water management $rograms& The com$any is a world leader in the develo$ment of industrial wastewater treatment, reuse, and recycle a$ $lications& Additional information can (e o(tained at the com$any Internet site+ www&$rochemtech&com