Industrial Water_r - Copy

8/18/2019 Industrial Water_r - Copy

1/35

Industrial Water


2/35

* Modern high-pressure boilers must be supplied

with feed water of high purity.

* As the water evaporates the concentration of

impurities in the liquid phase rise, dissolved and

entrained impurities accumulate, heat transferdeteriorates and boiler tubes are overheated, porous

sludges, crystalline scales, and other coatings appear

on the boiler metal.* Rising concentrations of specific soluble impurities

cause metal corrosion.

Boiler Feed-Waters


3/35

•

The most important boiler precipitates consist of silica iron,

suspended matter, and oil in addition to calcium and

magnesium as bicarbonates and sulfates. The principalfactors in corrosion are DO, CO2,

• low pH, and deficient alkalinity, can promote corrosion.


4/35


5/35

Boiler waters are kept to specification by one or more of the following techniques:

(1) External treatment for the removal of impuritiesfrom the raw water

(2) Internal treatment for the conditioning of water within the boiler

(3) Blowdown for the removal of concentrates andsludges


6/35

Cooling Water

• Water is the common coolant of the process industries

• Water has a high heat capacity, is almost universallyavailable, and is easy to transport and apply.


7/35

• Especially in re-circulating systems must cooling water

be treated to inhibit corrosion/ scales formation,

sediment deposition, and microbial growths.

The most important water properties affecting corrosion

are oxygen and other dissolved gases, dissolved or

suspended solids, pH, velocity, temperature, andmicrobic growths.


8/35

Irrigation water

Irrigation waters should not contain more than the limit the

following substances:

Sodium-5 mg/l

Boron — 0.5 mg/1Chlorides-5.3 mg/1

Sulphates — 10 mg/1

Total salts —

700 mg/l Specific conductivity — 1000 micro-mhos.


9/35

Excessive salinity at root-zone level leads in

succession to leaf burn, leaf drop, twig dieback, and

plant destruction. Salinity effects are largely osmotic.

High sodium exchange breaks down soil structures,

seals pores, and interferes with drainage, in extreme

cases of soil breakdown the pH of the soil may rise tothe level of alkali soils. Although traces of boron are

essential for plant growth, high concentrations are

injurious. Chlorides are generally more injurious than

sulfates, because chlorides are relatively more solubleand more toxic to some plants and because sulfates

are precipitated as calcium sulfate.


10/35


11/35

A free chlorine residual of at least 0.4 ppm must be

maintained throughout the pool. The alkalinity of thewater shall beat least 50 ppm, and a pH greater than

7.2 but less than 8.2 shall be maintained. Pool waters

should be highly transparent so as to keep divers

from colliding with bathers swimming under water.

To avoid rapid multiplication of saprophytic

bacteria, pool temperatures should not be raised

above 78 °F.


12/35


13/35


14/35


15/35


16/35


17/35


18/35


19/35


20/35


21/35


22/35

Softening


23/35


24/35


25/35


26/35


27/35


28/35


29/35


30/35


31/35

Ion Exchange


32/35


33/35


34/35


35/35

Documents

Industrial Water_r - Copy