Flare: smokeless operation with blower 1

[ChemE2912]

We would like to know for which king of hydrocarbons blower assisted flares shall be used when smokeless flaring is needed.

 

[panneflapper]

I would say when aromatics are involved you'll need a blower, aromatics have a very low smoke point. For other components you can look up their smoke point, this is the maximum length of the flame without the formation of smoke in a standardized test.

 

[Flareman]

When gases burn in an open diffusion flame like a flare, they make smoke because the hydrocarbon "cracks" and releases free carbon into the flame zone. The only air for combustion is normally available outside the flame so the carbon is resident in the flame for a short period and has the chance to physically "grow" into solid particles which then leave the flame as smoke.

Aromatics generally have a very low "cracking" temperature (as a function of the energy of formation) and so they start making free carbon quite early in the flame. (olefins and acetylenes too).
Attacking these with an air assisted flare seems like a good idea but it is very difficult because the oxygen speeds up the combustion and raises the flame temperature which causes the carbon to start forming even sooner. Eventually, unless you get an extremely good mix of air and gas, and use something approaching stoichiometric air (check out the potential volumes !!), you could be on a loser.

In my view, you would be better off using a steam assisted flare because the steam cools the flame and delays the "cracking". There are a couple of good designs on the market which also have steam/air eductors built into the tip, and give you some air as well. The combination will be more effective than just air.

Let me know if you need to follow up commercial ideas.


David