14 replies to this topic

[amad]

Can expert here, help me for understanding about Release N2 Purging.

My client ask me to release N2 purging to flare header. But, my supervisor said that releasing N2 purging to flare header is not recommended because it can turn off flare. In case of flare is off, it can be difficult if we want to turn on the flare (because of N2 content is too much).

Can anyone advise me? What is the best solution for releasing N2 purging?
Thank you for your attention.

 

Best Regards

 

 

Amad

[Bobby Strain]

My suggestion is to ask your supervisor where it should be purged to. Certainly if you are purging air, release to the atmosphere is what you should do. But you should not purge hydrocarbons  or other harmful materials to the atmosphere. To my knowledge, your only choice is to purge such materials to the flare. And inject enough flammable material so that you don't snuff the pilots. And hopefully, find a new supervisor who can offer some positive advice.

 

Bobby

[amad]

Thank Mr Bobby.

My supervisor said to release via atm and it is ok with his experience.

How with your experience about the topic? (release to atm or flare and why)

Thank's

 

Amad

Edited by amad, 02 May 2016 - 10:25 PM.

[fallah]

 

My supervisor said to release via atm and it is ok with his experience.

How with your experience about the topic? (release to atm or flare and why)

 

 

Amad,

 

Per the little info you provided and in general, it's preferred the N2 purge gas to be released via the flare network rather than venting system. To consider a protection facility for potential of pilot ignition system snuffing by large flow of N2, an reliable instant re-ignition system shall be provided in relevant flare ignition system...
 

[breizh]

amad ,

You should consider to calibrate the flow to your flare . It's difficult to assess what you want to do with the limited informations provided . You cannot release flammable material to atmosphere .

 

my thought.

 

Breizh

[amad]

Thank's all.

 

Mr. Fallah,

"reliable instant re-ignition system shall be provided in relevant flare ignition system..."

What is the example?

 

Mr Breizh

We have project to develop Procedure for "Cleaning Condensate Stabilizer". So, we develop the preparation before cleaning it (will be conducted by contractor). The plant should be shutdown, draining, and depressurize. Then, before open manhole, we should do N2 purging until LEL is less than 5%. At this step, my supervisor ask me to release N2 to atmosphere because it will be a problem if we release via flare. On the other hand, my client ask to release N2 to flare.

My point is I want to know about the rule, Is it OK to release N2 to both of atmoshpere and flare, or how? what is the advantage/disadvantage for these two method?

Thank's for sharing your experiences

 

 

Amad

[fallah]

 

"reliable instant re-ignition system shall be provided in relevant flare ignition system..."

What is the example?

 

 

Amad,

 

A large flow of N2 can snuff one or more fuel gas pilots; but having instant re-ignition system can turn on the snuffed pilot(s) to prevent flare stack to play the role of venting system rather than flaring...

[Julien123456789]

Amad,

As my experience, N2 is not recommended to purge to the flare system.

I prefer let it go to venting system at a safe location.

Considering to add a suppressor if necessary.

 

Julien

Edited by Julien123456789, 03 May 2016 - 07:45 AM.

[amad]

Mr Julien,

Your opinion is almost same with my supervisor.

I think it is a good discussion because I got different opinion from experts here that both of venting and flaring is method for releasing N2 purging (other company, other method/step).

I hope other expert give the opinion too.

Thank you

 

Amad

 

 

[senthil13]

Amad,

 

Purging N2 during a maintenance is very common. what we do is measure the volume of the purge of each vessel and we will control the purge to the Flare so that we don't put the flare off. We also make sure we have enough BTU routed to the flare (using nat gas) and we will maintain the flare during this operation. We have done this many times without any issues to the flare. 

 

Note that when you purge a vessel, you are not only sending N2. N2 will also carry other hydrocarbon /components from the vessel you are purging. So Don't send it to Atmosphere. 

 

As Fallah mentioned, if you have a automatic ignition system in the flare pilot based on temperature. It will help even if the flare if put off. It all depends on your regulations in the area.

 

Again, There is nothing called SAFE LOCATION. unless you do a dispersion modelling and determine the location. I have seen it many times people call it safe location and let the discharge of a PSV or vent to atmosphere which are very close to platforms and operating location which could be dangerous.

 

Hope this helps!

Senthil

Edited by senthil13, 04 May 2016 - 08:04 AM.

[Julien123456789]

Senthil13,

Thank you so much for your contribution. This is an interesting subject.

One project on which I designed, I need to add N2 from a blanketing to a hull (storage tank) during discharging oil.

Then, for balancing my ship, I need to transfer oil from tank to tank.

At this stage, N2 need to be evacuated. It means that it is a normal operation, not a maintenance period.

I agree with you that I used a dispersion model to determine a safe location.

 

In conclusion, it depends on the nature of operation, we define the method for purging N2.

 

Please correct me if something wrong.

 

Julien

Edited by Julien123456789, 04 May 2016 - 09:22 AM.

[breizh]

http://www.johnzink....nd-accessories/

 

Hi ,

 

Consider this resource to support your work .

 

Breizh

[danyelson]

Hi,

 

The safe location should be established based on a dedicated Dispersion study, and the corresponding safety measures should be considered, in order to mitigate somehow any possible risk.

 

Daniel

[manojkaila]

Dear Amad,

 

1 When you are purging any N2 with hydrocarbon first priority must be flare. Only you have to take care for release quantity. I have many time performed such activity and we never face any problem for pilots of flare. In your case N2 is with hydrocarbon which is it self fuel.

 

2 When you do not have any facility like flare then no other choice and you have to disperse in safe location with extra care.

 

3 Normally in flare at the end of all header some fuel gas or N2 always flowing as a purge gas. In you case if that gas in fuel gas the better.

 

4 Many people have different experience same like your supervisor but in available condition (your case is flare) we have to best safe system.

 

I hope this will make things little more clear.

 

Good Luck 

[amad]

Thank you all for your advise and opinion. new experience, new knowledge.

 

Amad