Multiple flares and thermal radiation

[wenchop]

API 521 states: "The impact of multiple flares in proximity operating simultaneously needs to be considered when evaluating thermal radiation."

What we have is a case of several flare stacks/risers in parallel in close proximity, so they are almost in the same location. The question is whether radiation can be calculated individually, then added to get a total radiation. For now, I want to use methods for radiation in API appendix, I do not want to use sophisticated proprietary software.

Thoughts?

 

[gerhardl]

Re radiation, questions for yourself:
Is all flares added together worst heat radiation situation? If yes, is total radiation within acceptable, managable level? How likely all flares activated at the same time? If all active at the same time, duration before lessening?

 

[wenchop]

Yes all go at the same time. The duration would be more than a few minutes.

If I want to find the minimum height for the flares, the assumption of adding the radiations may not be the best assumption (too conservative). It seems to me that the presence of a flare nearby will pull the flames of all flares upwards.

 

[Duwe6]

The flames will indeed be pulled upward by the draft of all the convection of all the flames, BUT the thermal radiation will still be a sphere and the center of that sphere will not rise much. Try 200-ft for an initial height of the stacks. Might calc OK.