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[syfq88]

Dear all,

 

Conductivity in condensate return system and boiler feed water in our plant above than the control limit, ~15microS/cm vs 10microS/cm. We suspected that the high conductivity was contributed by steam impurity. So we took saturated steam sample  and superheated steam sample to see if there is any ions carry over in our steam. 

 

The result is as below:

 

Specifications

Boiler 

Saturated Steam

Boiler 

Superheated Steam

pH

9.9

10.0

Conductivity, uS/cm

31.5

15.03

Silica, ppm

0.218

0.077

Chloride, ppm

6.4

0.2

 

It seems that there are ions carry over in our saturated steam from the steam drum and the ions might deposit on the tubes, resulted in low ions content in superheated steam.

 

But my question is, where do chloride ions come from? 

 

Conductivity in our demin water is <2microS/cm so I don't think the chloride is coming from the demin water. Moreover, silica content is lower than chloride ions in the steam system. Chloride ions also observed in boiler feed water and condensate return system.

 

What else could be the sources of chloride in boiler system?