8 replies to this topic

[mushk]

Hi guys, just wondering. I have read somewhere before that fuel gas is usually preferred as purge gas for flare system over inert gas. Has anyone have any idea why so?

[JoeWong]

Hi guys, just wondering. I have read somewhere before that fuel gas is usually preferred as purge gas for flare system over inert gas. Has anyone have any idea why so?

- Burn fuel gas produce CO2 lead to GHE. N2 is inert gas. No impact to environment.
- Use fuel gas for purging, flow is much higher (may be 10 times) compare to N2. From energy aspect, six sense tell me burning fuel gas consume more energy than generation of N2 (from flow aspect...), but i still have NO comparative figure to support this saying...
- Use fuel gas for purging, potential lazy flame damage flare tip. N2 purging has no similar problem.-

However, some plant i,.e refinery, there will be excess gas available which anyway you need to burn it. No point to use N2 in this case.

Edited by JoeWong, 22 August 2009 - 10:41 PM.

[Root]

Hi guys, just wondering. I have read somewhere before that fuel gas is usually preferred as purge gas for flare system over inert gas. Has anyone have any idea why so?

Hi,

Inert gas will extinguish the flare, 'ie' FG is given in flare system as purge gas.

Cheer

[Dacs]

Hi guys, just wondering. I have read somewhere before that fuel gas is usually preferred as purge gas for flare system over inert gas. Has anyone have any idea why so?

At the top of my head, fuel gas is readily available in a refinery and it's just not cost effective to use inert gas, which you have to buy somewhere else.

[JoeWong]

Hi,

Inert gas will extinguish the flare, 'ie' FG is given in flare system as purge gas.

Cheer

Some flare system will purge with Nitrogen.
No flame at the flare tip.
Pilots are on continuously and ready to ignite any HC gas come from flare header...

Edited by JoeWong, 21 August 2009 - 08:51 AM.

[JoeWong]

Other than

Burn fuel gas produce CO2 lead to GHE. N2 is inert gas. No impact to environment.
Use fuel gas for purging, flow is much higher (may be 10 times) compare to N2. From energy aspect, six sense tell me burning fuel gas consume more energy than generation of N2 (from flow aspect...), but i still have comparative figure to support this saying...
Use fuel gas for purging, potential lazy flame damage flare tip. N2 purging has no similar problem.

However, some plant i.e refinery, there will be excess gas available which anyway you need to burn it. No point to use N2 in this case.

In addition...use N2 for flare purge,
- eliminate visible flame. Some environment sensitive area demand for no flame flare design
- heavy fuel gas purge to flare lead to smoke flare. Steam injection required for smokeless flare. Therefore, continuous steam is required. Additional CAPEX (steam injection eductor) and OPEX (steam loss).

Edited by JoeWong, 21 August 2009 - 07:49 PM.

[Root]

Other than

Burn fuel gas produce CO2 lead to GHE. N2 is inert gas. No impact to environment.
Use fuel gas for purging, flow is much higher (may be 10 times) compare to N2. From energy aspect, six sense tell me burning fuel gas consume more energy than generation of N2 (from flow aspect...), but i still have comparative figure to support this saying...
Use fuel gas for purging, potential lazy flame damage flare tip. N2 purging has no similar problem.

However, some plant i.e refinery, there will be excess gas available which anyway you need to burn it. No point to use N2 in this case.

In addition...use N2 for flare purge,
- eliminate visible flame. Some environment sensitive area demand for no flame flare design
- heavy fuel gas purge to flare lead to smoke flare. Steam injection required for smokeless flare. Therefore, continuous steam is required. Additional CAPEX.

Dear Joewong,
I agree with you, my company also using N2 in oil field flares as purg gas and so far this called smokless flare.
thank you for correction.

[JoeWong]

mushk has triggered me to post a simple write-up...

Inert Gas or Fuel Gas For Flare Purge ?

Enjoy reading...

Edited by JoeWong, 23 August 2009 - 12:34 AM.

[VikingUK]

Hi guys, just wondering. I have read somewhere before that fuel gas is usually preferred as purge gas for flare system over inert gas. Has anyone have any idea why so?

Because it's cheaper !!! Purge gas is simply to keep air (oxygen) out of system.. also fuel gas burns...!!! no problems with need for propane ignitors