Nalco 3D TRASAR Series, Инструкция по установке и эксплуатации

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521-OM0108.88
Copyright
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2009 Nalco Company
6-22
Technical Help
(630) 305-CHEM
3D TRASAR
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5500 - Installation & Operation Manual
9. Does 3D TRASAR Bio-Control work with highly halogenated make-up water?
To test whether this system is suitable for 3D TRASAR Bio-Control, disconnect the external oxidant
feed and monitor the halogen residual in the system. If >0.1ppm total residual halogen is measured
in the system after an extended period of no halogen feed (>6hours) this system may not be
suitable for 3D TRASAR Bio-Control.
Does the Make-Up water come in big slugs (system water volume changes by >10% due to Make-
Up valve control dead band)? If so, this system may not work with 3D TRASAR Bio-Control. Use of
3D TRASAR Bio-Control in these conditions can cause blue coloration in the water.
We have run systems with Make Up water that have Total Residual Halogen of 3 ppm successfully
with 3D TRASAR Bio-Control, where the above two conditions did not apply.
10. Can 3D TRASAR Bio-Control be operated in monitor mode only?
No
. Nalco Bio-Index is a measure of how far the Rf/Rz ratio is compared to the set point. When
ratio exceeds set point + deadband, 3D TRASAR Bio-Control feeds oxidant. When ratio falls
below the deadband, 3D TRASAR Bio-Control stops the feed of oxidant (since the oxidant first
reacts with microbes and then with Rf and Rz). In other words, the ratio is maintained at pre-set
value by optimal dosing of “mini slugs” of oxidant.
If oxidant feed is controlled externally, it is likely that oxidant feed is not in “micro slugs”. This
means the ratio drops precipitously when excess oxidant is fed. The 3D TRASAR controller then
tries to compensate for bio-reporter loss by feeding more bio-reporter which a) lowers the ratio b)
can turn the tower blue because of reaction with excess oxidant.
The value of the Nalco Bio-Index itself is meaningless in this case because the ratio is not a func-
tion of microbial activity, but of oxidant levels in the tower. Another way of saying it is that for NBI
numbers to be meaningful, 3D TRASAR Bio-Control MUST be in control of when the oxidant pump
comes on (ratio has exceeded pre-set limit) and when it shuts off (oxidant feed is enough to kill the
microbes).
11. Will 3D TRASAR Bio-Control reduce my bleach feed?
3D TRASAR Bio-Control applies oxidizing biocide in response to microbial activity. It cannot be
tuned to add more or less biocide, it will apply biocide to the level that is necessary to control the
bio-activity.
If, prior to 3D TRASAR Bio-Control, the customer was underdosing biocide, 3D TRASAR Bio-
Control will increase the dosage. On the other hand, in systems with excessive biocide usage, it
may significantly reduce biocide usage.
Systems that maintained oxidizing biocide at a set halogen residual either by ORP control, or by
Hach Cl-17 control or even by manually-adjusted continuous biocide feed, have typically reduced
their oxidizing biocide usage under 3D TRASAR Bio-Control, sometimes dramatically.
Systems that were previously slug-dosed once per day to once per week typically record an in-
crease in oxidizing biocide usage under 3D TRASAR Bio-Control.