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OBJECTIVE
OF COOLING WATER TREATMENT
*Saves
Energy Losses
*
Increases Life of Costly
Equipment
*
Saves Water Cost / Pumping costs
*
Ensures Optimum Efficiency of
the plant.
*
Saves Frequent Acid Cleaning
Cost
*
Reduces Maintenance Cost.
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PROBLEMS
DUE TO WATER IN COOLING
SYSTEM ARE:--
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SCALING
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Factors
Causing Scaling in Cooling
Waters are:-
*
High methyl orange alkalinity
(ppm as CaCo3)
*High
Calcium contents (ppm as CaCo3)
*High
pH.
*High
dissolved solids, ppm.
[DO
YOU KNOW THAT IT HAS BEEN FOUND
AFTER YEARS AND YEARS OF
EXPERIENCE BY VARIOUS EXPERTS IN
THE WORLD THAT ORDINARY SCALE OF
CaCo3 HAVING THICKNESS AS LOW
AS 0.6 MM, CAN BRING ENERGY
LOSSES OF ABOUT 20% (
Fouling factor 0.002 )].
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CORROSION
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FACTORS
CAUSING CORROSION IN COOLING
SYSTEM:-
*
Dissolved oxygen
*
Temperature of water
*
Chlorides and sulphates
*
Carbon dioxide contents
*
Impurities in water ( Total
dissolved solids)
*
pH
*
Possible presence of free
mineral acid, sulphidem, So2
etc.
*
Scaling or other deposits on the
surface.
*
Over feeding / under feeding of
corrosion inhibitors
DO
YOU KNOW THAT 20 MPY RATE OF
CORROSION CAN REDUCE THE HEAT
EXCHANGER LIFE TO SIX YEARS .
1
MIL = 1/1000 inch.
Hence
a heat exchanger tube of
1/8" = 125 mils. Normal
corrosion rate without/ improper
treatment /
with soft water is 15 to 20 mpy
(case - a). Corrosion with
proper treatment is around 3 to
5 mpy
(
Case- B) Normal tube life
without treatment = 125/20 = 6
years (Case-B)
Depreciation
of heat exchanger without
treatment / improper treatment
Per
annum = 100/6 = 16% in Case A.
DEPRECIATION
WITH PROPER TREATMENT - 100/25 =
4% Per Annum.
HENCE
WITH PROPER WATER TREATMENT
PROGRAMME DEPRECIATION COST
CAN BE REDUCED FROM 16% TO 14%
PER ANNUM WHICH IS SAVING OF
75%.
CORROSION
IN YOUR BOILER REDUCE THE LIFE
OF BOILER AND CAN
LEAD TO SERIOUS ACCIDENTS.
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MICROBIAL
GROWTH
EFFECT OF ALGAE
GROWTH:-
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The
growth of algae on the
evaporative pads greatly reduce
their efficiency. For your
system to operate
at its maximum cooling capacity.
It is necessary to make sure
that algae growth on pads is
kept minimum.
Fortunately
this can be accomplished rather
easily by keeping in mind that
algae are simple plants that
like the plants in your
greenhouse ,they have three
basic requirements for growth;
LIGHT, MOISTURE AND NUTRIENTS.
*
Uncontrollable growth of algae
can cause serious problems in
cooling water systems.
*
This increases the rate of
deposits, on the smaller
particles which remain suspended
in water
will now form agglomerates and
settle down much faster.
*
Naturally formed fouling
deposits are loose and fluffy,
so can be easily flushed away
with high velocity
of water.
*
But fouling occurred in presence
of slime remains permanently on
the surface.
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FOULING
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*The
Cooling Water source may contain
suspended particles like dust
and dirt. Some of these also get
into the system through the
cooling tower.
*
Usually in low velocity areas or
when the plant is stopped during
night these particles settle
down on the surfaces giving rise
to deposits.
*
Deposits arising from settling
of these suspended particles is
called Fouling.
*
Normally, it is not possible to
distinguish scaling deposits
from those of Fouling, but
impact on
the process is the
same as scaling.
A
COMPLETE WATER TREATMENT PROGRAM
FOR COOLING
SYSTEM INCLUDES
*
Scale inhibitor / antiscalant to
prevent the precipitation of
alkaline earth salts.
*
An inhibitor to protect steel
from corrosion
*
An corrosion inhibitor added
specifically to prevent the
corrosion of copper and its
alloys .
*
An dispersant to prevent the
accumulation of deposits of silt
and other suspended material.
*
A surfactant to improve the
performance of biocide.
*
An acid to regulate pH of
recirculating water.
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Information 
