3 replies to this topic

[process_persia]

Dear all,

I have a problem in deciding among three options available for one blow down drum size in our plant. Our client wants us to study the three availeble possibilities for blow down drum size (leading to different flare loads). Attached you can see the three cases. I have also attached the diagrams regarding each case.

Which case do you think is the best option? (assume that there is no space limitation). it should also be noted that we have another unit adjacent to our plant sharing a common flare.

Thanks in advance

Attached Files

•  blowdown.xlsx   354.54KB   39 downloads

[herrani]

Hi!

After looking at your figures, it looks like the temperature and pressure in all three cases will be similar, and only the flowrate will change. This means that you are considering three different relief scenarios for the sizing of your drum and flare header, and the only difference between the three cases is the number of relief valves that will open during one relief case.

My advice would be to consider the causes of each relief scenario, and design for either the most probable one, or the worst case scenario. In order to provide some help with that, we would need some information about each case.

I hope this helps.

[process_persia]

Dear Herrani,

Thank you for your reply. In fact we are dealing with an emergency depressuring case due to fire case and these are the three alternatives for this scenario. do you have any idea how much the relief load from 100 t/hr to 200t/hr would affect the flare stack height and other related parameters?

BEST

[chemsac2]

process_persia,

You can calculate flare stack height and diameter from procedure outlined in API 521, Annexure C. Stack height is decided by radiation flux at receptor. API 521, section 6.4 gives details.

Regards,

Sachin