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CW TREATMENT
(CORROSION AND SCALE)
BY
P.SRIVASTAVASR. MANAGER(CHEM.)
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COOLING WATER
Cooli! o" #$%&' i $ &&%i$l 'o*& $%
o#&'+!&&'$%io $, i,-%'i$l l$%.
T& o% io'%$% -& o" *ooli! #$%&'i*l-,& *o,&i! %-'0i& &$-%
%&$ *ooli! 'o*& "l-i, $,
'o%&*%i! i! '&-'& - 0&$'i!.
Co%'ol o" *ooli! #$%&' *&i%' i 4&'
*'i%i*$l i '&4&%i! *o''oio $, "o-li!.
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COOLING WATER SYSTEMS
T& o" *ooli! #$%&' %& o% -i%$0l&
"o' 'o*& ,&&, -o+
1. P'o*& o&'$%io
2. 6lo# '&7-i'&&%
3. A4$il$0ili% $, 7-$li% o" #$%&'8. E4i'o&% '&7-i'&&% '&!$',i!
,i*$'!&
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T& o" *ooli! %&
1. Closed Recirculating
2. Once-through3. Open Recirculating (Evaporative
cooling towers)
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Clo&, R&*i'*-l$%i! S%&
9 W$%&' *i'*-l$%& i $ *lo&, **l&
9 Al%&'$%& *ooli! $, &$%i! #i%o-% $i'
*o%$*%9 H&$% $0o'0&, 0 %& #$%&' i *lo&,
%& i %'$"&''&, 0 $ #$%&' %o #$%&'
&*$!& %o %& '&*i'*-l$%i! #$%&' o" $
o& '&*i'*-l$%i! %& "'o #i* %&
&$% *$ 0& lo% %o $%o&'&.
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O*& T'o-! S%&
9 W$%&' $;& o& $ %'o-! %& &$%
&*$!&' &7-i&% $, ,i*$'!&, %o #$%&.9 L$'!& 7-$%i% o" #$%&' i &&,&,.
9 O*&+%'o-! %& $4& $,4$%$!& o" o%
*o*&%'$%i! #$%&' ,-'i! i% $$!& %'o-!%& %- '&,-*i! *$li! $, *o''oio
o%&%i$l o" #$%&'.
9 W$%&' i '&%-'&, %o o-'*& $% i!&'%&&'$%-'& %- *$-& %&'$l $, *&i*$l
oll-%io o" #$%&' 0o,i&.
9 Hi!l 'o& %o 0iolo!i*$l "o-li!.
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Co''oio Co%'ol
Corrosion inhiitors are used to control thecorrosion in CW sste, which are
9 4hosphates -When added to the sste, in
presence o! calciu, hardness will !or, acathodic inhiitor.
9 Chro,ates 5nodic inhiitor
9 6inc Cathodic inhiitor which provides
e7cellent pitting corrosion protection.
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Co''oio Co%'ol
9 Ti$ol& A $o,i* ii0i%o' %$%
&*i"i*$ll 'o%&*% %& &llo# &%$l.
9 Poo$%& C$%o,i* ii0i%o' #i*
%$% l$ ,o# oool&*-l$' "il o
&%$l -'"$*&.
9 Mol0,$%& A o %oi* &$4 &%$l %$%
i &*&ll&% $o,i* ii0i%o'.
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*C50E
A %& #$%&' **l& i *ooli! %& %&
*o*&%'$%io o" %& ,iol4&, io
i*'&$& -%il %& ol-0ili% o" o& o'
o'& o" %& *o%i%-&% i &*&&,&,.W& %i $& %& $%&'i$l
'&*ii%$%& o' 0&*o& $ oli, i #$%&'
$, i $4$il$0l& %o 0&*o& $ ,&oi%.
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+actors 5!!ecting *cale !or,ation
9 W$%&' %&&'$%-'&
9 Al;$lii%9 Co*&%'$%io o" *$l& "o'i! $%&'i$l i %&
#$%&'
S*$l& o**-''i! i *ooli! #$%&' %& Most Co,,on 0ess +re8uent
C$l*i- C$'0o$%& M$!&i- Sili*$%&
C$l*i- S-l$%& i* Po$%& C$l*i- Po$%& C$l*i- 6lo'i,&
I'o oi,& I'o C$'0o$%&
Sili*$
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E""&*% o" S*$l&
9 S*$l& "o' $ i-l$%i! 0$''i&' $, '&%'i*%
&$% %'$"&' %- ,&*'&$i! *ooli!
&""i*i&*.
9 6lo# '&%'i*%io %'o-! %-0&
9 Hi! o&'$%io *o%
9 P'o*& ,o# %i& *o% o& $, lo i
'o,-*%io9 @$"& 'o*& *o,i%io ,-& %o '&-'&
%&&'$%-'& &%*.
S l M i% i
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S*$l& Moi%o'i!
C$l*i- *$'0o$%& i %& o% *oo"'&7-&%l &*o-%&'&, *$l& i *ooli!#$%&' %&. I% "o' #& C$l*i- $,*$'0o$%& $l;$lii% &*&&, %& $%-'$%iol&4&l $, 0&!$ %o '&*ii%$%& $ *$l*i-*$'0o$%&.
L$!&li&' S$%-'$%io I,& (LSI) R&' S%$0ili% I,& (RSI)
A'& 4&' -&"-l i,i*& "o' ,&%&'ii! *$l&$, *$l& %&,&*i& o" $;& - #$%&'.
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S*$l& Moi%o'i!
To '&,i*% *o''oi4& o' *$l& "o'i! %&,&* o"
#$%&' "ollo#i! i,i*& $'& -&,.
9 L$!li&' S$%-'$%io I,&
LSI H + H
H (>.3 F A FB) + (C F D)
A +To%$l Diol4&, Soli, 6$*%o'
B + T&&'$%-'& 6$*%o'
C + C$l*i- H$',& 6$*%o'
D + Al;$lii% o" Cooli! W$%&'
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S*$l& Moi%o'i!
9 R&' S%$0ili% I,&
RSI 2H +H
LSI + F4& S*$li!
LSI + +4& Co''oi4&
RSI + A0o4& :.? Co''oi4&
RSI + B&lo# :.? S*$li!
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