Crude Furnace Excess O2
Crude Furnace Excess O2
(OP)
I have a problem with my crude furnace. The excess O2's are a little too high, currently around 7-8%. I would like to work on lowering them, but operations doesn't like the idea because they say the furnace cokes up faster when the O2's are lowered. This does not make sense to me. I would think that with higher O2's, you would have to fire the furnace harder to get the same transfer temp or outlet temp from the furnace. In their experience though, the furnace just cokes up faster. Does anyone have any ideas about this phenomenon?





RE: Crude Furnace Excess O2
RE: Crude Furnace Excess O2
RE: Crude Furnace Excess O2
RE: Crude Furnace Excess O2
rmw
RE: Crude Furnace Excess O2
Matt
RE: Crude Furnace Excess O2
Radiation [R], as a fraction of the total heat released by combustion [Q] in british units, relates to the mass ratio of air to fuel [G] by Hottel's equation:
where [a], is a factor that depends on the geometry of the firing chamber and the heated tubes projected surface.
For a given heater, just by reducing [G] the radiation % [R] would increase.
Hottel's equation was developed for pulverized solid (and liquid) fuels, but it is generally applied, w/o great error, also to gaseous hydrocarbon fuels.
In an old example I found in my notes for a cracking furnace fired with refinery gas, a reduction of [G] from 20.5:1, to 20:1 (a drop of 2.44%), resulted in an increase in [R] from 0.414 (41.4%) to 0.421 (42.1%).