Table 23 - Tendency Of Generation Of Scales And Corrosion By Quality Of Cooling Water - York YHAU-CE Installation Operation & Maintenance

SECTION 7 – MAINTENANCE
TABLE 23 - TENDENCY OF GENERATION OF SCALES AND CORROSION BY QUALITY OF COOLING
WATER
QUALITY OF COOLING
Water pH low
Water pH high
Water contains many
calcium ions (Ca
magnesium ions(Mg
Factors of
Water contains many
Water Quality
chlorine ions (Cl
Water contains many
sulfuric ions (SO
silica (SiO
Water contains many iron
(Ferrous ion (Fe
ion (Fe ))
3+
Water smells bad
(Contains sulfuric acid,
hydrogen sulfide (H
ammonium ion (NH
methane, or other
chemicals)
Water contains organic
matters (High COD and
BOD)
Exhaust gases (Sulfurous
Environmental acid gas (SO
Factors oxide (NO
chloride (HCl), ammonia
(NH ), or other chemicals)
3
mixed in water in cooling
tower
Solid matter (Mud, sand,
fibers, dust, insects) in
water in cooling tower
Sea wind (District by sea)
104
WATER
SCALE AND ITS COLOR
Hard scales are generated
and iron bacteria grow.
Calcium carbonate scales
are generated easily.
Sulfuric ion SO
and carbonate ion CO
) and
2+
combine together to generate
)
2+
hard scales.
──
)
-
Calcium sulfide (CaSO
calcium silicate (CaSiO
) and
2-
combine together to generate
4
)
hard scales.
2
Fe becomes ferric
3+
hydroxide (Fe(OH)
),ferric red water and deposits ferric
2+
dioxide (Fe
grow.
S), Scales are generated easily,
2
), and slime is generated.
+
4
Scales are generated easily,
and slime is generated.
), nitrogen If organic and inorganic
2
), hydrogen nitrogen are contained, algae
2
grows. SO
SO and combines with Ca
4
and Mg
2+
Scales are generated easily.
Solid matters set. Slime is
generated.
Scales are generated easily.
GENERAL TENDENCY
Pale
yellow
, silica SiO
2-
4 2
Pale
2-
3
yellow
) and
4
)
Gray
3
) to make Reddish
3
brown-
O ). Iron bacteria Black
2 3
Greenish
Blue –
Dark
brown
Algae:
Green
+ O becomes
Pale
2 2
2+
yellow
to generate scale.
FORM 155.35-ICOM2.EN.CE/GB (1018)
DATE: 10/30/2018
CORROSION AND ITS COLOR
Dark brown
Corrosion of iron and ~ Pale
copper pipes. greenish
blue
──
──
Iron and copper
tubes are corroded
badly.
SO Corrodes
2-
4
copper tubes badly.
Fe corrodes iron Reddish
3+
and copper tubes brown-
badly. Black
H S and NH Black –
+
2 4
corrode copper Greenish
tubes badly. blue
──
Exhaust gas from
automobiles,
factories, sewage
treatment
plants, ammonia
refrigerators, or other
contributing factors,
lower or raise the
pH. As SO , Cl and
2- -
4
NH increase, tubes
+
4
get corroded and
pitted very quickly.
────
Reddish
Tubes are corroded
brown-
badly.
Black
JOHNSON CONTROLS