MIL-HDBK-1003/11
11.4.5 Internal Water Treatment. All heat generating systems and cooling
systems, where water is heated or evaporated leaving cumulative solids,
should be treated chemically while the system is in operation. Table 11
gives the limiting boiler water concentrations for steam boilers and
Table 12
Typical Performance of Some Water Treatment
Average Analysis of Effluent
Treatment
Alkalinity
CO2
Dissolved
(as CaCO)
(as CaCO)
in steam
solids
Silica
(mg/l)[1]
(mg/l)
(mg/l)
(mg/l)
(mg/l)
Sodium zeolite
0 to 2
Unchanged Low to high
Unchanged
Unchanged
Sodium + hydrogen
0 to 2
10 to 30
Low
Reduced
Unchanged
zeolite
Sodium zeolite +
chloride anion
exchanger
0 to 2
15 to 35
Low
Unchanged
Unchanged
0 to 2
0 to 2
0 to 5
0 to 5
Below 0.15
Evaporator and
reverse osmosis
0 to 2
0 to 2
0 to 5
0 to 5
Below 0.15
[1] Milligrams per liter (mg/l) = parts per million (p/m).
11.4.5.1 Blowdown. Intermittent and continuous blowdown help to ensure
that water quality limits are not exceeded. Treatment of water makeup
assists in limiting the amount of dissolved solids entering the system.
11.4.5.2 Chemicals Used. The actual internal treatment with chemicals is
part of the operation. These chemicals can only be determined by water
analysis and the amount of makeup water required by the cooling system used.
11.4.6 Raw Water Treatment. Where turbidity is encountered in raw water,
the use of pressure filters with sand or anthracite media is recommended
upstream of all other treatment systems. Packaged pressure filter systems
for commercial and industrial use are available, ready for installation and
operation. Such systems are complete with all filter tanks, filter media,
piping, alum feeder, and valves. Where raw water contains excessive calcium
and magnesium ions, the use of pressure type sodium in exchange systems
(standard water softeners) will usually produce an acceptable makeup water
for cooling tower and closed circuit cooling system makeup needs. The
treating of complex water compositions requires detailed chemical and
physical analysis and treatment recommendations by competent water
consultants.
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