Concentration of the condensed sulphuric acid 1

[kpedde01]

Hello Everyone,

I am working on a flue gas system, the gas stream contains 0.068% - SO2; 40.962% - H2O;7.29 % - O2; 4.47% - CO2 i calculated the dew point temperature using two different equations and came up with 160.30 deg C and 162.90 deg C. My question is if i want to operate below the dew point temperature ( the acid condenses) what would be the concentration of the condensed acid and what would be the corrosion rate on a mild steel. if there are any equations or charts to determine this it would be helpful. I hope you can help me with this.

Thanks in advance.

 

[rustbuster]

The Dew Point of H2SO4 is ~138C according to API 571 if that helps

 

[blacksmith37]

You mean sulfurous acid - which is a worse condition. SO2 readily dissolves in water, so that first drop will eat your lunch/ so to speak/ and will have little to do with the overall composition of the gas stream. ( SO3 does not absorb in water nearly as fast as SO2 ). However, if you do condense sulfurous on the steel surface , it gradually turns to sulfuric .
Bottom line , the only thing you can do is try to prevent any liquid condensation (and try to monitor it to be sure).

 

[arguellesmanuel]

hello, for a mixture of several species (SO2, H2O, CO2, O2) is very difficult to predict behavior. Raoult's law holds for mixtures of two species in a vapor-liquid diagram for your case, taking into account the two higher molecular weight species (SO2 and CO2) and apply the diagram McCabe Thielen.

Greetings.

M. Arguelles