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#1 Guest_Frank Lloyd_*

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Posted 11 October 2012 - 02:00 PM

At what ppm as Sulfate do you feel becomes a problem when feeding sulfite into a non DA steam boiler.

#2 dhourigan


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Posted 11 October 2012 - 08:54 PM

Frank, I am not sure that I understand the question, but with no DA, the lowest temperature you could ever see is just above freezing (thermal stress would be an issue, I am sure), but at that temperature Dissolved Oxygen could be as high as 10 ppm.

Since two moles of Sodium Sulfite react with one Mole of Oxygen, we get 2 x 126 (gram-molecular weight of Na2SO3) reacting with 32 (gram-molecular weight of Oxygen). 252/32= 7.88...call it 80 ppm then to react with 10 ppm of oxygen not taking into account the purity factor. So, why ever feed more that 100 ppm of Sodium Sulfite.

Now your question was Sulfate, so lets convert Sodium Sulfite to Sulfite (80/126=.6349) (.6349 x 100 ppm = 63.5 ppm as Sulfite). Now convert Sulfite to Sulfate (96/80=1.2)(1.2 x 63.5 ppm = 76.2 ppm as Sulfate).

Why you need that, I don't know. I have no idea how high you can go or why you would want to find that out.

BTW: The coldest feedwater I have ever seen was between 50 and 55 degrees Fahrenheit.

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