33 replies to this topic

[PhilippM]

Bobby Strain, on 28 Sept 2019 - 03:59 AM, said:

Low and higher have no meaning to us. One must always assume that the vent will ignite. Then you must consider flame radiation affecting people and equipment. You don't have any steam available?

 

Bobby

Doesn't he also have to assume that the vent doesn't ignite right away, but instead a vapor cloud is formed that will ignite somewhere else (e.g. in a confined area nearby)?

In my opinion there is no point in using the flare only for the "1st release"

[Bobby Strain]

Steam is the only inert used for such an application. Yours is not the first instance. The purpose is to snuff any flame after the vent has ceased.

 

Bobby

[RRahman]

Hi Bobby,

 

I know that steam has been used as snuffing medium but I still feel nitrogen is better as the inert as steam has the tendency to condense and create vacuum, which we surely don't want.

[RRahman]

I know some vendors and contractors designed some snuffing systems in the past by using 1 to 3% of maximum vent stack flow (for the inert flow) but the theory behind this rule of thumb is still unknown to me.

 

Also, what will be the estimated time for each snuffing to extinguish the flame? E.g. 1 minute?, 30 seconds. This will dictate how many N2 cylinders you want to put in the design, assuming you are using a skid system.

[gegio1960]

farid,

the attached old paper seems the most focused on the original request

 

Attached Files

•  Husa - how to compute safe Purge Rates.pdf   435.52KB   64 downloads

[farid.k]

gegio1960, on 02 Oct 2019 - 1:26 PM, said:

farid,
the attached old paper seems the most focused on the original request

Dear sir. This really helps!! I do really appreciate this

[PhilippM]

gegio1960, on 02 Oct 2019 - 1:26 PM, said:

farid,

the attached old paper seems the most focused on the original request

I'm confused: I thought a snuffing system is supposed to extinguish the flame in case the vapour released from a vent is ignited. The paper however is about purge rates of flare and blowdown stacks in order to avoid a flammable mixture inside of them. Why would the purge rate be the same as the snuffing rate?

[breizh]

Hi Farid ,

you may question this company  , they should be able to support you :

 

https://www.johnzink...g at vent stack

 

Good luck

Breizh 

[gegio1960]

ref #32

 

 

   api 521 vent stack.JPG   34.45KB   10 downloads