9 replies to this topic

[renin]

Pls I need assistance over this issue. I am trying to design a system that collects well fluids and sends them to a two phse separator to separator the gas from bulk liquid. A certain amount of gas is tapped off from the separated gas and used as fuel gas for the gas generator. The remaining gas is mized with the separated bulk liquid and then sent through a pipeline to another platform for processing. The client doesn't want a flare system for the system I m trying to design. My dilemma is where will the separator PSV relieve to? Can I route the relief to a close drain drum? And if I route it to the drum, how will I size the closed drain drum? Will it be sized like a normal flare KO drum to deal with the gases that might come from the PSV if it's sized for block discharge? I would appreciate ur swift professional solutions pls. Thanks.

[Bobby Strain]

You need first to examine any local codes that regulate these installations. As to swift, we are under no pressure to meet your deadlines.

 

Bobby

[Zauberberg]

For looking into this problem, I believe a sketch or a PFD is definitely required.

 

Secondly, we do not know the operating/design parameters of the facilities, and which are the Codes that have to be followed in this case.

Finally, we do not know the allowable/available overpressure protection alternatives as per the Client's standards.

 

API 521 does not restrict you from relieving into another, lower pressure system, but the designer must demonstrate feasibility of such a solution and make sure the relief capacity will not be adversely affected. Drain system, in any case, does not look like a good idea to me.

[fallah]

renin,

 

Please upload a simple sketch of the system you described...

[renin]

this is the pfd

Attached Files

•  pfd.bmp   1.72MB   53 downloads

[fallah]

renin,

 

It looks like closed drain drum wouldn't be a proper option to which the PSV relief (mostly gas) being routed. Please specify the composition and rate of the relieving fluid to study if  dispersion or routing to a safe location can be a reasonable option... 

[himant]

Just a opinion!

 

If your client is insisting not to have a flare system, then why to give any isolation between your design facility and processing facility. Provide control valve to fuel gas system and no isolation between separator and processing facility.

 

Just make sure system upstream of separator is designed for well fluid design conditions.

Edited by himant, 17 June 2015 - 05:14 AM.

[shan]

1.  You may have a "vent system" instead to "flare system".

2.  It is a common practice to combine closed drain tank and flare/vent scrubber into a single vessel.

3.  You have no way to test an individual well because both your production header outlet and test header outlet are the separator only without any alternatives. 

[Faisal Ghafoor]

In one ammonia plant where I have worked, the PSV containing liquid and gas was routed to an open to atmosphere wash tower having trays and water supply at top. The remaining gas was going to atmosphere at safe height and liquid was being drained. It was BFW/syn gas service.

[roslan1966]

Dear Renin,

 

You may size the closed drain based on typical flare KO drum + volume of liquid drained from other sources. The vent from the said closed drain shall be vented to safe location.

 

roslan