increasing pH of Steam after passing through an exchanger

[mim_ASEMAN]

briefly ,
we have an Exchanger witch due to get warm and cold (both) the solution in the shell,
first , pure steam with pH=7 & temp = 200 C pass through the tubes ,
and then cooling water with pH 8.5 & Temp 25 C (Hard water include RO reject + Well water - but still saturated ) pass through the tubes ,
but when we test the outlet steam , the pH is 10.5 !!! how it can possible?
i thought the X-Valve witch switch between cooling water and steam , may has Leakage ,
but the pH of water is 8.5 ! it can't make the pH of steam 10.5 !

so , i think when the coolant water , touch the hot body of tubes , because of thermal shock ,
carbonate calcium can scale in tubes ,
and then , steam can dissolve them in itself and as a result , we observe pH increased !

may it true ?

 

[EdStainless]

Have you bothered to analyze the steam to find out what is in it?
And how are you measuring steam pH anyway? I presume that you condense it, have you tried de-gassing the condensate and remeasuring?

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P.E. Metallurgy

 

[Mconlon]

Sure your analyzer is accurate? Did you replace the probe and still get a similar reading?