6 replies to this topic

[Shailesh kshirsagar]

Addition of flare recovery system ( buckling pin and pressure control valve) can create blockage in the flare system.
I am not aware of flare recovery system. can any one guide on this issue.

[jrtailor09]

Dear Shailesh,

Flare gas recovery is implemenetd by very less organization in india. Actually this system will required some study means daily normal flaring load being flared by refinery.We have to calculate the payback period by installing the flare gas recovery system to the gas recovery.

As per my knowledge only Reliance & might be essar implemented Flare gas recovery system.

Please go through API 521 for the basic of Flare gas recovery sytem & concept.

Refer attached file also for the preliminary details.

Regards,

Jatin

Attached Files

•  Article Flare gas recovery _hp.pdf   1.24MB   188 downloads

[rblanton]

Dear Shailesh kshirsagar,

I would be happy to assist you. We have many more references in addition to the fine article gratiously posted by Jatin.
Please visit our website, http://www.johnzink....e-gas-recovery/
or send me an e-mail message, roger.blanton@johnzink.com.

Roger

[jrtailor09]

Thanks roger.

[GSaikrishn]

Shailesh,

a) Flare gas or Off gas recovery unit is basically a unit installed in refinerty set up to recover the flared hydrocarbons and reduce fuel emmissions to atmosphere.

Normally the flare header carrying the unit emmissions are diverted to a flare knock out pot to knock out condensibles.

the gases then pass through the water seal and into the flare stack.

c) Now for a flare recovery unit, a tap off from the flare header at the upstream of water seal is taken. this header is then diverted to a compressor which compresses, these waste gases and usually discharges them into a fuel gas header, wherein the fuel gas is used as a heating medium for fired heaters, boilers etc.

So essentially by providing a flare gas recovery unit, u are simply recovering the hydrocarbons lost in the process units and utilizing the same gases as a process heating media.

Now, as for your question, what is buckling pin and where is this pressure control valve installed in your flare system.

Regards
Saikrishna

[Boeid]

Shailesh,

One of the gas plants in the company that I am working for is currently constructing/installing a flare gas recovery unit (FGRU) though I am not directly involved in this project.

Just to continue the explanation by GSaikrishn on point ©

d) The FGRU is designed to take a certain flow of gas - the flare system operates at a wide range of flow, from very low comprising only by sweep/blanketing gas (during normal operation) up to a very high flow when there is a major upset in the plant (rare occassions). The FGRU will not be designed to cater for the max capacity of the flare system as it will be a waste of CAPEX. A sweet point (certain value of flow) is to be determined between [low flow recovery at most of the time] and [high flow recovery but on rare occassions].

e) Up until this "sweet point", the flare gas will be diverted to FGRU to be recovered.

f) Anything above this - depending on the amount of flow and length of period it happens - will create pressure build up in the flare system as FGRU can take/receive a certain flow only. Left unattended, the FGRU will eventually trip.

g) In order to avoid this, the excessive flow need to be diverted (back) to the flare stack. This is where buckling pin relief valve (BPRV) comes into the picture as one of the possible solutions. Other solutions are rupture disc, water seal tank and pressure control valve. All have a similar objective - to divert the flow to the flare stack when a certain pressure value is reached in the flare pipeline.

h) BPRV is a good alternative for rupture disc, as once activated it can be reset just by changing the buckling pin cylinder WITHOUT shutdown the flare system, unlike rupture disc where the flare system need to be shutdown to replace the disc.(you need to reset the BPRV or change the rupture disc when everything is back to normal in order for FGRU to be back online).

Further info on BPRV:

http://www.bsbsystem...ds_catalog.html

[Satheshchem]

Can any one tell me the standard operating procedure to check liquid hydrocarbon in the horizontal flare water seal drum using try cock?also skimming off hydrocarbon liquid layer from the horizontal flare seal drum??