SO3 in Flue Gases

[yulinios]

Hello to everybody
I would like to know if is possible to calculate SO3 in flue gases of coal boiler having 1200 mg/Nm3, I would like to set my Dew Point knowing, so I need to know SO3 concentration.
Bye there

 

[rmw]

Check thread605-84707, and the second post of thread798-02257, which will take you to many other threads.

rmw

 

[athomas236]

rmw,

The second thread in your post is about the aire pressure distribution around a telescope dome. Was this your intention,

athomas236

 

[25362]

Yulinios, the 1200 mg/Nm³ refer to SO2, right ?
There is enough moisture in the flue gases to enable the formation of sulfuric acid when the SO2 converts to SO3.

This humidity comes from a variety of sources, such as hydrogen in the coal composition, free moisture in the coal, moisture in the combustion air.

What is exactly that you wish to find ? Is it the amount of SO3 formed ? Please clarify.

 

[rmw]

How about thread798-92257 It is called operator error.

Thanks for the correction, athomas236.

rmw

 

[athomas236]

Vulinios,

Why not just buy a dewpoint meter. I think there is a UK company called Land that make such a meter.

athomas236

 

[yulinios]

Hi Everybody

Thanks for your valuable answers, our coal boiler sometimes needs to work at minimum load (wich is less than the manufactures manual indicates), the temperature of flue gases in the exit of Chimney at design load is 132 C (295 F) it decreases at minimum load to values as low as 107 C (250 F), so I was looking information in the book "Combustion Fossil Power" where I found a Curve "temperature of flue gases vs PPM SO3", since we have a SO2 meter on line I was thinking the ways to calculate SO3 if it is possible or take samples to measure it, set one alarm in control room is one thing that I would like to get.
Thanks again

Bye there

 

[25362]

From a ChE Plant Notebook article published Feb.9, 1981, titled "Predicting dewpoints of acid gases" by Yen-Hsiung Kiang (Trane Thermal Co.) for sulfurous acid (H₂SO₃):

1000/T_dp=3.9526-0.1863ln(P_H2O)+0.000867ln(P_SO2)-0.000913ln(P_H2O)ln(P_SO2)


T_dp is in degrees K, P is partial pressure in mm Hg. The error is claimed to be small.