10 replies to this topic

[binzee]

Dear All,

Can some one please advise what is recommended practice /Standard temperature for storage of LSRN (Light Straight Run Naphtha) as well as its Battery limit temperature.

Another supplementary question is,

A PSV is installed at LSRN storage vessel, where should its (PSV) outlet be connected incase it cannot be connected to flare.

Earliest Response would be very much appreciated.

Regards,

[Qalander (Chem)]

Dear,

Your query has two distinctive issues in it;
Storage/Rundown Battery Limit Temperature for the stream
Pressure Relief Valve issue.

I only touch the first issue right now and as I know/understand ,this is customary to have the temperatures near-ambiant as other wise

1) We unneccessarily loose recoverable (heat) energy contained in the stream.
2) higher temperatures result in
(a) Higher product evaporative losses being highly volatile nature.
( The higher RVP(vapour pressure effects the internals of tank(s)and the sealing system

Hope this helps for now
Regards
Qalander

[Zauberberg]

As already explained by Qalander, the product rundown/storage temperature should be determined based on average/maximum ambient temperature, product composition and RVP, and finally the storage tank type and operating pressure. In general, keep it low enough to avoid excessive product losses and safety concerns due to higher rates of LSRN evaporation.

Light naphtha storage tank usually operates at atmospheric pressure, and unless you have dedicated vapor recovery system in your tankfarm, I can't see where else you can go with the vapors developed inside the tank. So keep the LSRN cold enough - it's always better to treat the cause, rather than symptoms.

[Qalander (Chem)]

Thanks Zauberberg, for justified seconding.

Dear binzee; The other issue as indicated by my friend Zauberberg; has to be financially viable and that is very much on case to case basis/depends on

1)Storage tank size(s) and
2)Gains from recovery!
3)Penalty savings from recovery!

Hope this helps
Regards
Qalander

[binzee]

DEAR ALL,

Thanks for your valuable inputs....

In summer we have ambient temperature between 45 and 50 C and LSRN rundown remains between 38 C and 44 C, where as in winter the ambient temp is between 0 C to 20 C rundown temp varies between 32 C to 38 C.

We are about to commision LSRN Bullet type vessels for storage, the PSVs require an outlet, which should be flare. Unfortunately at present it is not possible to use existing flare for the said service. Till such time we upgrade our flare system what should be the disposal in case PSVs pop up.

As far as keeping LSRN cold is concerned, would it help much if we have an external fire case?

Can we dispose of the vapors directly to the atmosphere or else they require routing through the blowdown vessel/knock out drum or any thing else.

Your guidance and expertise is requested.

[Qalander (Chem)]

DEAR ALL,

Thanks for your valuable inputs....

In summer we have ambient temperature between 45 and 50 C and LSRN rundown remains between 38 C and 44 C, where as in winter the ambient temp is between 0 C to 20 C rundown temp varies between 32 C to 38 C.

We are about to commision LSRN Bullet type vessels for storage, the PSVs require an outlet, which should be flare. Unfortunately at present it is not possible to use existing flare for the said service. Till such time we upgrade our flare system what should be the disposal in case PSVs pop up.

As far as keeping LSRN cold is concerned, would it help much if we have an external fire case?

Can we dispose of the vapors directly to the atmosphere or else they require routing through the blowdown vessel/knock out drum or any thing else.

Your guidance and expertise is requested.

Dear binzee, I am unable to reallize
1)How to damage environment through indiscriminate venting of light hydrocarbons as indicated.
2)This is definitely a good large source of energy should not be wasted un-accounted
3)Recovery systems Gas holder tanks(low pressure external floating roof) with hydraulic seals design venting into some blowdown should be studied alongwith knock-out.
4)Otherwise this should be used in Fuel gas System of the facility in question or it may be sold to nearby gas company or bottled as LPG subsequently .
Best regards
Qalander

[binzee]

Dear binzee, I am unable to reallize
1)How to damage environment through indiscriminate venting of light hydrocarbons as indicated.
2)This is definitely a good large source of energy should not be wasted un-accounted
3)Recovery systems Gas holder tanks(low pressure external floating roof) with hydraulic seals design venting into some blowdown should be studied alongwith knock-out.
4)Otherwise this should be used in Fuel gas System of the facility in question or it may be sold to nearby gas company or bottled as LPG subsequently .
Best regards
Qalander

Thanks for the reply,

Firstly, I am not suggesting that we should be sending light hydrocarbons into atmosphere, but was just seeking advice whether we can vent them into atmosphere or not as they are potentially dangerous.

Secondly, they may be a good source of energy but in how many instances would you come across such a situation like external fire resulting in opening of PSV.... the piping cost and auxillary items may not justify its use like this. When you are facing a fire scenario or any other such problem one would like to keep the things as simple as they possibly can....

I believe your proposal for blowdown/knock out system is more practical and safe...

Thanks indeed for the great advice.

[Qalander (Chem)]

Dear

nothing to unsettle anyone!

Actually the reason of my stopping atmospheric venting was on the same fire(accidental ignition and flash back as happened in texas BP ameriaca plant) scenario's perspective.
As for safe venting may be too high a vent location will be in-evitable

Additionally during my early days with previous employer while controlled emptying an LPG pipeline; I physically witnessed, that might and usually does lead to a catastrophe.

(An un-disturbed carriage of white LPG plume in winter days visible during dark hours upto around 100 plus feet)

Hope this helps.
Best regards
Qalander

[binzee]

Thanks a lot for sharing your experience and guidance.

[Qalander (Chem)]

Dear

Since the vapors from LSRN are expected to be almost 75%~85% LPG An incident pdf is attached for Hazards Scenario visuallization.
Regards
Qalander

[binzee]

Thanks a lot sir...

regards,