EcoWater CHC Series, Руководство по обслуживанию и устранению неисправностей

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5.10.3 Silica Scale
Silica Scale is a type of scale caused by dissolved Silica levels in the basin increasing above the
point in which they can no longer sustain solubility. This type of scale will be deposited on
heated surfaces and is not affected by acid and must be removed my manual means. Things to
verify are as follows:
1. Cycles of Concentration too High
a. Out of calibration- The meter may not have been routinely calibrated to ensure
accuracy. The calibration may have been affected by using an out of date calibration
standard, once the standard is used passed 50% or is brown in color, EcoWater CHC
recommends discarding the standard and opening a new one. Verify the correct
units of measure are used from the calibration standard label. The probe may be
dirty or scale may have formed on the tip affecting calibration (use Rydlyme and or
a mild soap solution to clean the probe tip as instructed in the manual). The probe
may be defective (normally seen by a probe that is out of calibration by more than
100 points routinely (complete self test of probe on all Walchem units)). A
defective meter can also cause an out of calibration situation, if the meter will not
calibrate to match a calibration solution or it fails the self test function (Walchem
only) replace the meter.
b. Inappropriate or inadequate flow across conductivity probe. If there is not enough
flow across the conductivity probe, its readings can be lower than normal causing
the system to cycle up and scale. It is important to have at least 5-8 GPM flow
across the probe to ensure accurate measurements. EcoWater CHC also
recommends that a submerged probe is not placed into the tower, these types of
applications can also give an erroneous measurement valve causing cycles to climb.
c. Suction piping too close to Make-Up water distribution. If the suction piping is too
close to the Make-Up water’s valve, you can get a conductivity reading that is
diluted with the lower Make-Up water’s conductivity. This will cause the actual
tower water’s conductivity not to be measured and the blow down will not occur
when expected causing high cycles of concentration.
d. Incorrect Bleed Set Point. Verify that the Set Point is appropriately selected to
match the desired cycles of concentration as compared to the conductivity to the
Make-Up water, or as specified by water analysis.
e. Inoperative Blow Down Valve. Verify that the valve opens and closes as instructed
by the conductivity meter as well as the combo timer. You must verify that water is
drained from the system as the valve is opened and closed. The drain flow must be
strong and represent pump pressure during the opening of the valve. Inappropriate
flow may be an indication of an incorrect setting of the flow regulation valve,
plugged separator drain or plugged piping.
f. Scale can also be caused by flow problems within the customers system. If the
water is suddenly stopped or weakened in flow within the heat exchanger or
condenser, the temperature at those sites can suddenly increase causing scale to
form.
g. Changes in Make-Up water chemistry or source can affect the ability to form scale.
If the source for Make-Up water changes or chemistry changes it is possible that the
Cycles of Concentration could be affected and promote scale formation.
2. Cycles of Concentration did not reflect current Silica levels in the Make-Up water. If the
Silica levels within the Make-Up water suddenly increase, it is possible that the sump levels