4 replies to this topic

[Ganesh Buddha]

hi, i have been in exposure with oil refineries since i was 18 yrs old and it has been almost 20yrs. a very common and unanswered mechanism is the corrosion in flue gas stacks of fired heaters especially having an air preheater heated by flue gas. i have seen oil professionals banging their heads when they find preheaters and stacks getting corroded due to sulfur compounds. this is when i find them referring to dew point curves  of H2S. which i think is futile as there is always corrosion even when the flue gas temperatures are more than dew points of H2S for the current concentrations of H2S. they keep repeating the mistake with great ignonimity on depending on H2S dew point curves even when they are pointed that the curves are very incomplete.

 

 

please comment

[vectorangel]

Dear Ganesh,

I am also facing the same problem as you. please refer to my post below;

https://www.cheresou...-fired-heaters/

 

Dear all,
Now a days, we are having a problem in our refinery regarding heater stack flue gas analysis. It is very strange to have h2s in stack flue gases as it is an oil fired heater. I can not disclose quantity of h2s in the flue gas as it is confidential.
I did an extensive search to trace the origin of the culprit but could only find it in the storage but in vapor phase. Fuel oil is mantained at a temperature of 60 oC in the tank and then it fired with the excess air in the forced draft box type heaters. Is it possible that vapor phase h2s condenses during transfer to heater and then it vaporizes? But the pipeline and tank is completely insulated and heat traced with steam.
Did any one of you experience the same problem, then please guide me in this respect? Your valuable suggestion will be very much helpful to me.
Regards,
Qasim

 

Could you please guide me that how this H2S is forming in the stack fluw gases?

 

Regards,

Qasim

[Zauberberg]

What you are referring to is acid dew point corrosion, caused by condensation of SO3 in flue gas flowing through the air preheater.

 

There is plenty of resources on the internet, just google "acid dew point corrosion" or "cold end corrosion". V.Ganapathy wrote a lot of good articles on the subject - see http://v_ganapathy.t...m/corrosion.pdf

[Ganesh Buddha]

What you are referring to is acid dew point corrosion, caused 

 

Dear Ganesh,

I am also facing the same problem as you. please refer to my post below;

https://www.cheresou...-fired-heaters/

 

Dear all,
Now a days, we are having a problem in our refinery regarding heater stack flue gas analysis. It is very strange to have h2s in stack flue gases as it is an oil fired heater. I can not disclose quantity of h2s in the flue gas as it is confidential.
I did an extensive search to trace the origin of the culprit but could only find it in the storage but in vapor phase. Fuel oil is mantained at a temperature of 60 oC in the tank and then it fired with the excess air in the forced draft box type heaters. Is it possible that vapor phase h2s condenses during transfer to heater and then it vaporizes? But the pipeline and tank is completely insulated and heat traced with steam.
Did any one of you experience the same problem, then please guide me in this respect? Your valuable suggestion will be very much helpful to me.
Regards,
Qasim

 

Could you please guide me that how this H2S is forming in the stack fluw gases?

 

Regards,

Qasim

hi,

 

H2S in stack gases is often originating from cracking of high molecular sulfur compounds in the fuel.

 

well he SO3 originates from combustion of h2s and other sulfur compounds. the acid corrosion is not just from SO3 but even from H2S and the more often diagnosed to be originating from SO3 condensation or h2s ondensation.

 

the dew point curves don't necessarily point out for corrosion which happens at temperatures higher than the dew point indicated in the curves.

[Ganesh Buddha]

hi,

 

H2S in stack gases is often originating from cracking of high molecular sulfur compounds in the fuel.

 

well he SO3 originates from combustion of h2s and other sulfur compounds. the acid corrosion is not just from SO3 but even from H2S and the more often diagnosed to be originating from SO3 condensation or h2s ondensation.

 

the dew point curves don't necessarily point out for corrosion which happens at temperatures higher than the dew point indicated in the curves.