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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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