Q & A > Question Details
We are experiencing falling of coke particles from the refinery hydrocarbon flare stack of late during sudden increase of gas flow subsequent to operation of dump valve of hydrocracker. We would like to know whether such incidents have occurred elsewhere ? If yes, what are the probable reasons and how can they be mitigated ? It may be noted that flare gas velocity during dump valve operation is well below 0.5 Mach.
25/03/2008 A: SImone Robinson, Tube Tech International Ltd, simone@tubetech.com
The reason could be due to vibration caused by flow turbulence and a result of frequency change caused by the difference in gas flow.
I recommend you carry out an On-line inspection of the flare line especially at the base to establish level of build up which would impact on your flow and back pressure.
During our “On-line” cleaning of flare lines we regularly notice major build up at the root of the flare stack and the bends nearest to it, in almost every case, which in time inevitably leads to backpressure.
Deposits tend to be pyrophoric in nature, sludge-like as well as hard sulphurcrete included in the coke like deposition.
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