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Problem:
A 2,600 ton cooling system is used to cool Building #107 at
the Rohm & Haas facility in Bristol, PA. A study was performed to determine
the chemical savings associated with the elimination of scale inhibitors used in
the water treatment program by installing an ED2000 -- Electronic Anti-Fouling (EAF)
System.
Prior to installation of the EAF System, chemical costs were $10,239 in 2000 to
maintain the system and keep it free of scale.
Cooling Equipment
- 1400-ton Trane Centrivac
- 1200-ton Trane Centrivac
- Three 1500-ton Marley cooling towers
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Solution:
The ED 2000 solenoid coils were placed on the condenser supply
line, the condenser return line and the tower make-up water line. The
ED2000 control unit was mounted within close proximity of the chiller.
- Chemical Savings -- The initial chemical treatment program
consisted of a scale and corrosion inhibitor, dispersant, and biocide.
After installation of the ED2000, the scale inhibitors and then the
dispersants were eliminated. The copper corrosion inhibitor and
biocide were continued. Chemical costs were reduced from $10,239 to
$5,000.
- Energy Savings -- The average cooling load is 700 tons at
an annual cost of $137,877. A 3-degree increase in the condenser
approach temperature would increase the energy costs by 5% or more.
Condenser approach temperature records show the the ED2000 controlled scale
buildup and there was no degradation of thermal performance. Estimated
savings of 5% or over $6,500.
- Payback -- The cost of the ED2000 system provided an 18-24
month payback in this particular case.
- Environmental Benefits -- The cost savings do no include
the environmental benefits associated with using this type of treatment
program -- no disposal and pollution problems and no handling of hazardous
materials.
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Photograph of chiller tubes after the EAF
test period. |
Photograph of chiller tubes after the EAF
test period. Small amounts of scale in lower-left corner are
build-up from a prior period. |
An inspection of the chiller showed a
substancial amount of iron deposits being removed from the channel box
and tube sheet. |
A deposit analysis indicated 98% iron
deposits. This is build-up from prior treatment periods. |
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