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[ogpprocessing]

Dear All,

I have seen for some of the plants, the designer consider different flare stacks (for example HP and LP or even LP, MP and HP) to be located at common structure. What should be the justification for this kind of design? I do not see much benefit with this design because:

1. The flare stack design will be more complicated because combined design cases including the radiation from both of the stacks should be studied.

2. At the end all of the stacks which sharing common structure should have similar height which for sure will be higher than the case if each stack have its separate structure and is studied separately.

Let me know your idea and experiences.

[kkala]

I understand it concerns multiple flare headers & tips supported by a derric structure (http://kolmetz.com/p...lare Rev1.1.pdf. Advantages can be capital savings on the supporting structure, as well as on the "restricted" ground area (if any) around the flare base.That is on the area where radiation at max flare discharge exceeds acceptable limits, so people have to run out of it to escape.
Concerning the latter, attached "flare.xls" compares two cases of a pair. The pair consists of two flares, each 220 ft high and with max heat release of 4E+9 Btu/h (about 100 t/h of hydrocarbon gases). In first case headers & tips are supported by a common structure, so they are close to each other. In second case headers & tips are located separately at a distance.
Under the specific conditions of "flare.xls": savings on total "restricted" area exist in case of a common derric, only when max discharges from both flares cannot occur simultaneously; then "restricted area" is limited to what is required for one flare. It gets doubled if the two flares are located separately at a distance.
But if max discharge can occur simultaneously from both flares, "restricted" area seems to be much bigger than total "restricted" area of both flares.
Check and advice would be welcomed, since I am not familiar enough with flares. Even though books and web report it, I do not know whether "restricted" areas are still in practice. Probably modern flares develop ground radiation low enough for people to tolerate it without escape?
Nevertheless I have seen flares beside each other in a refinery, although supporting structures looked distinct.
Note: Attached "flare.xls" takes info for radiation from http://www.gasflare....From-Flares.pdf.

Attached Files

•  flare.xls   18KB   82 downloads