Marley Primus P11, User Manual

Page: 23 / 40

23
Wintertime Operation:
The Marley fill system used in the Primus cooling tower has air entrance
louvers that are molded integrally as part of the fill. This feature makes
these towers very forgiving of cold weather operation, even at the low
temperature and reduced load conditions encountered in free cooling and
other low temperature applications. Nevertheless, during operation in
subfreezing weather the opportunity exists for ice to form in the colder
regions of the tower.
Slushy, transitory ice forms routinely in the colder regions of the fill
of low temperature towers, and is visible through the tower louvers.
Such ice normally has no adverse effect on tower operation, but its
appearance should be a signal to the operator to undertake ice
control procedures.
It is the operator's responsibility to prevent the formation of destructive
(hard) ice on the cooling tower fill. Certain guidelines should be
followed:
1.
Do not allow the tower’s leaving water temperature to drop below a
minimum allowable level—say 36 ° F to 40 ° F (2 ° C to 4.5 ° C). If such low
temperature operation is necessary or beneficial to your process,
establish the minimum allowable level as follows:
During the coldest days of the first winter of operation, observe
whether any ice is forming on the louver face, particularly near the
bottom part of the louver face. If hard ice is present on the louvers,
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 observation is advisable.
If the minimum allowable cold water temperature is established at or
near maximum heat load, it should be safe for all operating conditions.
However, if established at reduced load, increased heat loads may
reintroduce the potential for icing.
Having established the minimum allowable cold water temperature,
maintaining that temperature can be accomplished by fan manipulation,
as outlined in Item 4 under Tower Operation page 22. However,
in
towers of more than one cell, where fans are manipulated sequentially,
Operation
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Caution
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Note