SPX Cooling Technologies CoolingTower Marley MCW - Manual (Page 15)

15
Wintertime Operation:
During operation in subfreezing weather, the opportunity exists for ice to
form in the colder regions of the tower. Your primary concern is to prevent
the formation of destructive ice on the cooling tower fill. Your under-
standing of cold weather operation will be enhanced if you read Marley
Technical Report H-003
“Operating Cooling Towers in Freezing Weather”,
augmented by the following guidelines:
1. Do not allow the tower’s leaving water temperature to drop below a
minimum allowable level—about 35°F—established as follows:
During the coldest days of the first winter of operation, observe whether
any ice is forming, particularly near the bottom of the fill. If hard ice
is present, you must increase the allowable cold water temperature.
If the coldest possible water is beneficial to your process, ice of a
mushy consistency can be tolerated —but routine periodic observa-
tion is advisable.
If the minimum allowable cold water temperature is established at
or near minimum heat load, it should be safe for all operating condi-
tions.
Having established the minimum allowable cold water temperature,
maintaining that temperature can be accomplished by fan manipula-
tion, as outlined in
Tower Operation: Item 4 on page 13. However,
in towers of more than one cell, the limiting temperature established
applies to the water temperature of the cell or cells operating at the
highest fan speed —not necessarily the net cold water temperature
produced by the entire tower.
2. A fan operating in a forced-draft tower is subject to the risk of freez-
ing. Icing is a particular danger as this can form not only on the fan
blades, but also the inlet guard. Ice particles can be thrown off and
cause severe damage. The fan casing should be checked so that any
water entering it (either from the tower or external sources) can drain
away. If water is allowed to collect in the fan casing, the fan could be
frozen into place. This could result in damage to the drive system if
starting were attempted
Operation
Caution
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