4 replies to this topic

[sunil_chemical]

Dear ALL,

Can anybody knows about the off-shore Flare header design. As in Off-shore flare header design, sometime flare header located in another platform and flare header is going through under sea water ???

Do anybody have any example for this kind of arrangement.

Please if anybody knows let me know.

Thanks

Sunil

[gvdlans]

I do not fully understand your question. The experiences I have with offshore flares is that they are either connected directly to the main platform (see for example offshore flare boom) or the flare stack is located on a separate flare platform that is bridge linked with the main platform (see for example bridge linked flare). With a subsea flare header there would be the risk of liquid build-up at the low point resulting in liquid slugs going to the flare.

Edited by gvdlans, 24 March 2010 - 03:36 AM.

[sunil_chemical]

Thanks for the Reply.

Why I am asking this question, because in Aspentech new version V.7.0 they have added new feature in flare header analyser in External Heat Source, Previously only air is present but now Sea water is also present. When I asked this question to aspentech they said in past few customer made this kind of arrangement in Sub sea flare header network. Where flare header is going through under sea water. I was also surprise that it is possible that flare header is going through under sea water. So I am very keen to see this kind of arrangement.

So I thought that share this thing with you all. Weather anybody knows about this kind of arrangement??

As you said, Huge amount of liquid slug is going to flare header and back pressure is also built-up. But it is trial and error method. I am guessing!!

And once again thanks for sending the off-shore flare header picture. if you will get any information regarding this kind of arrangement Please let me know.


Regards

Sunil

I do not fully understand your question. The experiences I have with offshore flares is that they are either connected directly to the main platform (see for example offshore flare boom) or the flare stack is located on a separate flare platform that is bridge linked with the main platform (see for example bridge linked flare). With a subsea flare header there would be the risk of liquid build-up at the low point resulting in liquid slugs going to the flare.

[JoeWong]

I remember this issue has been discussed last year or years before...

This kind of design (long header crossing subsea and relief via independent flare platform) has been implemented >30 years ago. This could be the results of unavailable sophisticated flare technology (tip) and immature offshore bridge structure design. There are several issues with this kind of design :

• Flame-Out & Gas Cloud
• “Fire Rain”
• Surge and severe vibration
• Internal corrosion
• External corrosion
• HSE issue

More discussion in "Why not bury flare pipe header ?"

I have worked on this kind of platform years back. It is an existing facilities. When we conduct the flarenet studies, header submerged in water can not be modeled and the request has been sent to Aspentech. Believe there after, Aspentech just simply include this feature to please "important" client.

With sophisticated flare technology (tip) and mature offshore bridge structure design, higher flare boom and longer bridge can be provided. This helps to avoid subsea flare header design.

[sunil_chemical]

Thanks Joe,

So I think aspentech added sea water option is not useful much, they have added just because of some customer said or discussed with them as u said.

Otherwise it is very difficult to do such kind of design. you already mention some of the problem regarding this.

Thanks once again.

Regards

Sunil

I remember this issue has been discussed last year or years before...

This kind of design (long header crossing subsea and relief via independent flare platform) has been implemented >30 years ago. This could be the results of unavailable sophisticated flare technology (tip) and immature offshore bridge structure design. There are several issues with this kind of design :

• Flame-Out & Gas Cloud
• “Fire Rain”
• Surge and severe vibration
• Internal corrosion
• External corrosion
• HSE issue

More discussion in "Why not bury flare pipe header ?"

I have worked on this kind of platform years back. It is an existing facilities. When we conduct the flarenet studies, header submerged in water can not be modeled and the request has been sent to Aspentech. Believe there after, Aspentech just simply include this feature to please "important" client.

With sophisticated flare technology (tip) and mature offshore bridge structure design, higher flare boom and longer bridge can be provided. This helps to avoid subsea flare header design.