Cold Flare Vs Dry Flare

[zacharialamsyah]

Dear Eng Tips Community

Kindly any of you can explain briefly the different between Dry Flare and Cold Flare, it is associated with HP or LP flare? Is the Ignition system between them different?

I googling, but still not get good definition of that terms.

Thanks for your response and answer

Regards,
Zachari Alamsyah

 

[EmmanuelTop]

Cold flare actually is the dry flare - the name originates from low temperatures achieved by depressurization of cryogenic, dry, typically high-pressure fluids, into a separate flare network (dry flare). Separate dry flare network is required in order to prevent from mixing extremely cold, dry gas, with gases containing water vapor (gases from "wet" process sections) - which would potentially cause severe problems (freezing, hydrates) and disable relief capacity of the flare. That is why cryogenic systems are discharged to dry flare, and wet systems are disposed of in wet flare system.

See also

http://www.eng-tips.com/viewthread.cfm?qid=416121

there is a lot of info referenced there.

Dejan IVANOVIC
Process Engineer, MSChE

 

[LittleInch]

Not to be confused with a cold vent, which isn't a flare at all, just a pipe....

So a cold or dry flare could be either a HP or LP flare system.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

In upstream low temp gas plants, you'd typically have a cold dry HP flare, a warm wet HP flare and a common LP flare.
As far as I know, either flame front generator or spark ignition type ignition systems can be used for any of these - redundancy in some of the subcomponents (including thermocouples for flame detection) for either of these is preferable. Talk to the flare tip vendor for many other details. If redundancy is provided, then overall reliability would be about the same for either types.

Typical problems associated with flares are
Failure to light up on startup
Flare tip thermal damage due to inferior materials or flame lick
Carbon deposition on the flare on LP flares and sometimes on HP flares
Smoky flares.
Some of these problems are due to operating the flare at low flows resulting in incomplete combustion and flame lick. Providing air or steam assist is often done on LP flares and for operational HP flare loads to enable good turndown and smoke free operation. In high H2S operation, sulphur deposition due to incomplete combustion around the flare tip is a danger.

 

[zacharialamsyah]

Actually I means Wet Flare and Dry Flare definition.

Thank you for response and answer. Seems clear now

 

[MortenA]

@zacharialamsyah, you must accept that many of these names were "cooked up" by the project engineers working on the original design project and dont have a firm industry accepted definition. Maybe, but only maybe, there is a company definition but only in large companies such as Shell, BP etc.

Best regards, Morten