Integrating two flare systems

[BenNeal]

A 3rd gas processing train is being added to existing two trains. The existing ones have a common flare system. The 3rd will have a new flare. My questions are:

1. Can both flares be built in the same area? is there any spacing requirements?

2. To design the new flare for the capacity of the total three trains, what are the possible restrictions?

3. what information of existing flare system would be required for the design of the new one?

 

[hiebs]

Hi BenNeal,

Are you asking us how to design a flare system? This is not an easy question, and a lot of people have learned this from many years of experience. Two of your best sources for information on this are API 520 and 521. However, there may be other references if you are not in North America or are offshore.

1. Where are you located? There may be rules for spacing two flare stacks. If you are on land, the main concerns would be ground level heat flux and impingement of the flame from one flare stack on the other (make sure that you are taking into account guy wires if it is a smaller stack).

2. Check flare stack size, FKOD size and flare system back pressures. Check governing codes in your area.

3. Maximum continuous flare flow, maximum instantaneous flare flow, blowdown rate. You must consider every valve, PSV and dump entering into the flare system. In some circumstances safeguards can be implemented to minimize flare flow.

My experience is limited to smaller gas plants and oil batteries in Western Canada. Good luck!

Hiebs

 

[PAN]

I understand that the height of two flare stacks should be the same. However, I do not have reference paper for supporting this design.

 

[Homayun]

BenNeal,

I personally do not see why both stacks can not be located in the same plot space or location.

However, unless you consider failure of all 3 trains at the same time, it may be worthed to examine carefully whether you really need a 3rd flare system! Ususally flare systems can protect multiple trains. So It may be possible to tie-in the new train into this existing flare system as well.

Another reason why you want to install a 3rd flare could be that the new train is larger than the existing 2 trains.

Try however, to establish the maximum premissble back pressure at the tie-in point, if you would consider using the same flare for the 3rd train as well. If you exceed that pressure, you may want to only enlarge the flare tip, stack and main header.

 

[BenNeal]

Thank you guys for the responses. They were informative and enlightening. I'll keep you posted how it will be addressed.