Purpose of heaters in flare KO drums

[Teresek]

The heaters in the boot of the flare KO drum on "my" platform are currently out of operation.

I have tried to find out if the heaters are defined as a part of the security system (we are discussing weather they can be removed permanently or not). In the Engineering Manual the purpose of the heaters is described as follows: "Electric heaters are located in the boot of the drum to heat cold liquid prior to pumping (maintain minimum temp of 5 deg Celcius). " From this, it seems like the heaters are a pump protection (to protect the drains pump on the KO drum liquid outlet).

On the other hand, what if wax, ice, etc blocks the outlet to the level instrumentation. If this happens, the level will "freeze" and we will no longer be able to detect HH liquid level. This will be a very critical situation.

In my seek for answers I have looked to several other platforms. The size of the heaters vary a lot, from a few kW to 3x50kW on "my" platform.

To summarize:
Does anyone know if the KO drum heaters are defined as a part of the security system?
Does anyone know any sizing rules for KO drum heaters?

 

[MortenA]

Try and read API 521 in my edition (4. march 1997) its in section 5.4.2.4 - Design details, ad. g): "Provision should be made for heating the content of the vessel (flare drum) where cold weather, autorefrigeration, viscous or congealing liquids may introduce problems."

Som additional details follows (read it for your self).

So if "your" plaform faces environmental conditions as described or the liquid that may end up here does then i would say that you should get the heaters fixed because they are indeed a "safety system".

Best regards

Morten

 

[SmartEngineer]

From past experience, I have seen heaters at the following locations with the intended purpose of each:
- Lube oil Reservoir: To maintain lube oil temperature at high level to prevent high oil viscosity.
- Fuel Oil tanks or drums: same reason as above
- Tar collection drum: To avoid plugging of piping carrying the liquid flow with high tars content
- Cold Flare KO drum: To vaporize the liquid accumulated at the drum from various relief sources or liquid drains sources. Some places are not having a pump (cryogenic pump) and instead a piping boot is usually provided with temperature indication allowing transferring the warm accumulated liquid to another destination by motive gas as Nitrogen. Also, to prevent liquid carryover to the superheater provided downstream of KO drum for superheating the cold flow release preventing damage of downstream CS piping.

I hope this would help

Cheers