3.8.1 Scale Formation
In a cooling tower, water evaporates and potentially enables mineral deposits to form
a “scale” on surfaces. If such a scale does form, it acts as a barrier to heat transfer,
and the performance of the cooling tower will degrade. Possible sources of such
scale are hard water and/or inadequate blow-down [21].
If hard water is present, water softeners combined with adjustment of the blowdown rate will likely prevent further formation of scale. The advice of a reputable
industrial water treatment service company may prove valuable in such a situation.
Removing existing scale deposits can be difficult. Hard water deposits generally
will dissolve in a mild acid backwash. But if scale is thick and/or has had the
opportunity to dry, it may have to be manually chipped off surfaces.
3.8.2 Clogged Spray Nozzles
Again, hard water can cause deposits to form in the spray nozzles that introduce the
water into the cooling tower. Alga or other solids may also cause deposits. Spray
nozzles should be inspected as a result to verify that the proper flow pattern of water
into the tower is present on a regular basis. If partial plugging occurs, the flow of
water over the fill will be uneven and water/air contact surface will be lost. Consequently, heat transfer and tower performance will suffer. A proper water treatment
program recommended by an experienced water treatment company should be
followed.
3.8.3 Poor Airflow
Poor airflow through the tower will degrade tower performance. Various causes can
partially interrupt airflow – debris in the tower exit, in the entrance, or in the packing
will cause unwanted and undesirable air currents to form that will short circuit parts
of the tower. Loose fan and motor mountings, poor fan alignment, damaged fan
blades, gear box problems, and other various problems can all contribute to poor
airflow as well. Thus, regular maintenance visual inspection of the cooling tower is
important.
3.8.4 Poor Pump Performance
If pumps (recirculation, blow-down, etc.) are not performing properly, then water
flow through the tower will be degraded as will tower performance. Again, preventative maintenance is preferable to an emergency shutdown. Perhaps most instructive are case studies of problem cooling tower installations [22–24].
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Y.-T. Hung et al.
In a cooling tower, water evaporates and potentially enables mineral deposits to form
a “scale” on surfaces. If such a scale does form, it acts as a barrier to heat transfer,
and the performance of the cooling tower will degrade. Possible sources of such
scale are hard water and/or inadequate blow-down [21].
If hard water is present, water softeners combined with adjustment of the blowdown rate will likely prevent further formation of scale. The advice of a reputable
industrial water treatment service company may prove valuable in such a situation.
Removing existing scale deposits can be difficult. Hard water deposits generally
will dissolve in a mild acid backwash. But if scale is thick and/or has had the
opportunity to dry, it may have to be manually chipped off surfaces.
3.8.2 Clogged Spray Nozzles
Again, hard water can cause deposits to form in the spray nozzles that introduce the
water into the cooling tower. Alga or other solids may also cause deposits. Spray
nozzles should be inspected as a result to verify that the proper flow pattern of water
into the tower is present on a regular basis. If partial plugging occurs, the flow of
water over the fill will be uneven and water/air contact surface will be lost. Consequently, heat transfer and tower performance will suffer. A proper water treatment
program recommended by an experienced water treatment company should be
followed.
3.8.3 Poor Airflow
Poor airflow through the tower will degrade tower performance. Various causes can
partially interrupt airflow – debris in the tower exit, in the entrance, or in the packing
will cause unwanted and undesirable air currents to form that will short circuit parts
of the tower. Loose fan and motor mountings, poor fan alignment, damaged fan
blades, gear box problems, and other various problems can all contribute to poor
airflow as well. Thus, regular maintenance visual inspection of the cooling tower is
important.
3.8.4 Poor Pump Performance
If pumps (recirculation, blow-down, etc.) are not performing properly, then water
flow through the tower will be degraded as will tower performance. Again, preventative maintenance is preferable to an emergency shutdown. Perhaps most instructive are case studies of problem cooling tower installations [22–24].
222
Y.-T. Hung et al.