The pH value of the condensed water return stream is on the high side
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As the title suggests: the pH value of the condensed water returning to the system is on the high side. The water supplied to the boiler is normal, with a pH of 7–7.5; the steam condensate exiting the boiler also has a pH of 7–7.5. However, the pH value of the condensed water recovered by the system itself is as high as 9.2. Equipment problems can be ruled out at this point. Could anyone please provide an explanation? Thank you!
During the boiler feedwater process, it is generally necessary to adjust the alkalinity; if ammonia is added, it evaporates along with the water, and upon condensation the pH value becomes alkaline. The water in the boiler is itself alkaline, which is a requirement for boiler feedwater.
In normal operation, the boiler uses chemicals, usually trisodium phosphate (soda ash), to maintain the pH of the boiler water between 9 and 11, that is, at an alkaline level as mentioned by those who came before. The alkaline pH value of the condensate mentioned by the poster is mainly caused by the impurities present in it.