Firebox Average Temperature

[shvet]

Good day, forum

I have a question concerning firebox average temperature. I have an exhaust from naphtha reforming catalyst regenerator containing some degree of dioxines. This fluid is routed to radiant section of naphtha reforming fired heater via a nozzle in the bottom of firebox where it is mixed with flue gas. Estimated bridgewall temperature is 770 °C.

I have to assess % of destruction of dioxines taking into account temperature, % of O2 and residence time. For this purpose, I need average temperature of flue gas in firebox.

Q1: Please share how to assess temperature(s) in forebox based on bridgewall.

Q2: Licensor stated that it is a customary industry practice in European region to routed this dioxines-containing exhaust to the firebox of a fired heater. I can not find traces of this practice in google, please share a discussion or your experience is this method efficient or this is just a way to lower down concentration of dioxins below measurement limit.

Q3: In the past, I have read emission of dioxins has become a cause of shutdown of naphtha catalytic reformers in California and New-York, but now I can not find this texts. Please help with clues.

 

[0707]

if you don´t have thermowells maybe with an infrared camera through the pep holes or some openings in the burners.

luis

 

[0707]

https://www.youtube.com/watch?v=f_A2Wrq7LVM

lm

 

[georgeverghese]

Take a look at the process data sheet for this fired heater. It should give you some idea what the average radiant section temp is. Initial flame temp at the burner should be approx 1500-2000degC, assuming excess O2 is managed well. Else you can backcalculate this from the heat picked up in the radiant section, but this is a more tortuous route to getting this value.

Dont know if this approach of using the average radiant section temp is acceptable, since reaction rates are an exponential function of temp. It may be better to calculate this by breaking this temp decrease from initial flame temp to bridgewall temp of 770degC in say 3-5 steps, rather than using an "average" temp.