We have a HP flare that unfortunately burns hydrocarbons badly, batch wise. I checked some scenarios like sudden change in gas flow rate (sweep gas, all source of gases sent to flare line) and no significant change in gas flow rate is seen once the flare batch-wisely burns hydrocarbons. I also checked the level of K.O. drum of flare for any disturbance during this problem and it was also constant. The air blower is also checked and they were good. I feel this problem originates from wind at the tip of flare but not sure. I appreciate your comments.
Hi Yadollah
Did you check published subjects ?
http://people.clarkson.edu/~wwilcox/Design/FlareSel.pdf
I am not sure if regular windpressure is disturbing an hp flare in the way you described.
unfinished burning might be a problem of the burning temperatur.....
good luck
dear frank
thank you for your answer, i have already read thus files. as you might know, some gas treating plants are near to urban cities and once we see a batch flaring process, the environmental section complains. our problem is not burning heavy hydrocarbons (HC) or smoking of flare. let me explain more. Consider t=0, the flare burns HC normally, at t=10 s, the flare highly smokes and at t=15 s, the flare returns to its normal condition. i though that we might have irregular flaring gas or leakage or disturbances changing the level of the flare knock out drum. but our PSV, PCV, BDV and sweep gas and ... act normally from t=0 to 15 s. i also feel that partial condensation occurs in the knock out drum and i am going to warm up it to see if any change procured by this method. you comment is appreciated.
Wind can cause issues with some HP flare tip designs. You can check this out if you can get a video of the tip during the transitions that you have described. If wind is an issue, then you should see the origin of the flame moving to just the downwind side of the tip during the smoking period. When the wind speed drops a little, then flame front should then move back across the full tip and you get burning as intended.
You should also do a thorough inspection of the tip to verify that you do not have holes or cracks in the tip that are allowing air to get into the gas stream or HC's to leak out prematurely.
Finally, you should check the design flow rate for the tip. It is not unusual for the maximum flow rate for the tip to be designed for emergency blowdown conditions and not the rates of everyday flaring. This frequently means that the tip is operating at only few percent (maybe 1 to 5) of the design conditions. If this is the case, the only way to "fix" the problem would be to change the design of the flare top to one with multiple tips or else separate the systems so that you have a production flare and a different emergency flare (which is very difficult to do correctly).
dear prof. Smith
thank you for your suggestions. once i get there, i will upload video file for this situation. any defect in tip of flare will be identified when overhaul arrives. the history of tip doesn't shows this defect but i will inspect it for more investigations. Thank you again
As the video file shows, flare suddenly starts smoking and then back to its previous state.
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