phosphates in the cooling water. future problems?? 1

[arguellesmanuel]

Hi, I have a cooling system (evaporative condenser) with the following conditions:

1. The makeup water containing 2 ppm of ortophosphates. (Used as corrosion inhibitor in the pipeline).
2. This water is used to feed a cooling system which uses an alkaline dispersant based on phosphonates.

Anyway, I have in my system two sources of phosphates.

3. Typical analysis on the makeup:
TDS: 200 ppm
pH: 7.2
Ca: 50 ppm
Alkalinity: 120 ppm
Si: 50 ppm
PO4: 2 ppm
4. I work at 3 cycles maximum (based on silica) and handling temperatures near 35 degrees celsius in the evaporative condenser.

Typical analysis in the evaporative condenser, usually:
TDS: 800 ppm.
pH: 9.0
Ca: 200 ppm
Si: 150 ppm
Alkalinity: 350 ppm
Phosphonates: must be between 2 and 3 ppm.

I wonder if my system is exposed to calcium phosphate precipitate or other forms of phosphates?.

Thanks for your responses.

M. Argüelles
Water Tech
Venezuela

 

[bimr]

From what you have presented, it is not possible to make a prediction.

However, you should maintain your water quaility within the manufacturer's recommended limits.

You should review this with your chemical treatment supplier.

I see no reason to continue with the orthophosphate program on the pipeline. Other programs such as raising the pH are more effective than phosphates. Change out of the phosphates may eliminate your phosphate problem.