Dear Friends,

I am contratcting the basic design for a complete relief system, including Flare Stack and Knock Out vessel. The engineering company bring to discussion if we would need any fire preventing system (sprinkles; etc.) for KO vessel and near the stack bottom in order to avoid fire in case of fire rains (our processes could relief latex together with the gas and it could eventually reach the flare tip. As a matter of fact, it already has occured in a similar plant).

Is there any recommendation (API; NFPA; etc.) that could help me to specify what kind (if there have to be any) of fire protection system should we have to have in our flare area?

Thanks in advance,

LCMS.

 

ICMS
Well since no one has responded, I will throw out a comment.   Many flare stacks are located at least 200ft from any processing areas.   This would give you some room for a rain of fire.    I would just plan for the rain and not worry about the sprinkler system.   Creating a sprinkler system grid around the flare seems difficult and costly.   You might consider lowering your flare tip to ground level, to reduce the radius of the "rain".   A good sized knock out pot in front of the flare may take care most of this issue as well.

Regards
StoneCold
 

Dear Stonecold,

Thank you for your answer. As you have mentioned, since only you send me a comment, I am starting to think that this concern could be a little bit stupid. As a matter of fact, I have never thought about this matter until the engineering company in charge of this project (a relief system) arouse the question. Now I decide to tell them to forget about it since we will warn our people to keep away the flare radiation area (probably including a fence).

Best Regards,

LCMS.  

Our basic design plan is to keep a flare radius of 1.5 X stack height of bare ground (clay) or unburnable materials.  

Rather than move to a sprinkler system, it might be smarter to enhance the separation of the phases with either additional separation, maybe a water wash?, or perhaps some additions like dixon plates, separation baffles, gas dome, etc....why wait for the fire to rain down?  Although having seen it, it's quite un-nerving.

Dear maddocks;

Thank you for your tip. In our design, the flare stack height is 100 ft and our radiation protected area (not clay, but small rocks that have the same effect - be unburnable as you said) is 150 ft, so we agree in this matter.

Besides, I fully agree that if everything we design works properly (separation vessels - we have 2 in series - and the knock out drum at flare stack basis) there should ver be a fire rain, but in our former system (that actually we never were allowed to comment, since bellongs to another company) it have occured. Even so, I intend to isolate this area just in case.

Regards,

LCMS.  

Just a little thing;
in case strong/appreciable winds are regularly encountered at location
then the pipework,vessels,occupancies should be separated by larger distance or
safely protected on "Usual Downwind Side"against spill fire,I believe.

Hope this is not very much delayed and proves useful!  

Best Regards
Qalander(Chem)