FPSO cargo tanks vent

[aneskd]

Dear Gen;
I looking your help for finding solution to our serious problems during venting of cargo tanks of FPSO especially with calm weather (gas” H2S” falling onto the vessel main deck/process modules triggering process gas detection system and subsequently causing an ESD )

Proposing solutions;
-Extend the existing vent length from 10 to 18 m
-Install blowers near specific vent to try dissipate the gas
-Install low pressure compressor for recovering the gas

Your assistance is highly appreciated

 

[RTMbra]

Hello!

Where are you working?
I am facing the same problem here in Brazil, and the received proposal was to install two new vents on either boards of the FPSO.
I really do not think this will be the best option, but for now, is the one being considered.

Please tell me if you found another solution...

Regards.

 

[MortenA]

Is this related to the situation where you are filling the tanks?

Are the vent line purged (e.g. with smoke or inert gas)?

Are the vent lines supplied with "relief valves" in "" because i cant remember the right term -but they are spring loaded valves that will release the pressure once a pressure of a few mbar has build up and close again at near atmospheric?

 

[gr2vessels]

There are very strict IMO regulations regarding the emissions on the ships. You did not quantify those emissions, but its likely you need to capture and recover those gases. It also puts you on the right side of the environment protection issue.

 

[MortenA]

gr2vessels

? I have helped design vents on two fpso, and have never heard of vapor recovery for these (or any particular strict emission rules)? IMO have no legal authorities i would assume, so each country must adopt the convention and implement this in their laws. So they may choose to leave out certain types of vessel, and bvesides FPSO never reaches habour when the take in oil.

Best regards

Morten

 

[gr2vessels]

Sorry Morten, my answer was in reference to the OP, not questioning your answer.
However, I have also worked on the venting gases on FPSO and offshore platforms. Toxic gases were recovered/separated before entering the venting system.
I agree that the rules are not mandatory except in American, Australian waters and other signatories of IMO rules. Obviously, there are level of emissions allowed, so the quantifying is critical.

 

[MortenA]

Yeah, im fine I just wanted to see if i missed something. I think we are in line: Vents from tankers may be covered by rules and regulation and the IMO has rules, that some countries have adopted. I dont know about Brazil? I have a question, however, do you think that rules in most places would cover off-shore facilities, or only tankers in habours? I would assume the latter but i dont know?

 

[gr2vessels]

Typically the offshore platforms are only covered by the territorial rules;- Australia is promoter of even stricter rules and restrictions, particularly in vicinity of eastern and north east waters around the Great Barrier Reef, but includes also PNG with special alliance rules. US is very strict within souverain waters, North Atlantic is another area of restrictions for vessels and platforms. However, the small back doors are always open, like diluting the emissions below the measurable threshold and letting the quantities go without proper records...No many countries adhere to these rules and many prefer to cheat. However, only developed countries can afford FPSO's and offshore platforms, so I assume they are promoters of environment protection. The rest are chucking over the board everything, letting us to pick up their dirt.
Cheers,
gr2vessels

 

[DuncanM]

In the UK, at least, an FPSO is NOT a ship. It is an oil producing installation; hence it is not subject to normal shipping regulations (like IMO, MARPOL etc) but those pertaining to oil producing installations.