11 replies to this topic

[umeshCHE]

We hav a case where the KOD is not performing, resulting in significant liquid carryover to the flare tip. Most of the liquid falls on ground like burning oil.

 

1. Compared to installing a bigger KOD, replacing the flare tip would take less time (faster delivery of tip by flare vendor, compared to KOD vessel).

 

2. Is it possible to replace the flare tip such that it can handle higher liquid flow (say larger oil droplets of 2000 micro-meter, compared to original design of 300-600 micrometer size).

 

Any body dealing with such issue, pl provide inputs.

 

 

On positive side, facility is operating for  long time, so the flare gas flowrate is much lower than original design flow. This may allow for replacing the flare tip of diff spec.

 

 

 

Thanks.

Apurv.

[umeshCHE]

Additional info of the topic above:

 

It is elevated gas flare, air assisted.

[Lowflo]

Atmospheric flares are not designed to be liquid burners. As described in your original message, liquids create a significant hazard to people and property.

 

Contact the manufacturer of your flare to determine its specific limitation.

[Art Montemayor]

To my knowledge, there is no burner built that will burn a liquid without atomization.  Only fuel vapor will burn, not fuel liquid.  Atomization is first done to breakup the liquid into particles such that they can be vaporized and subsequently burn.  But to do that, you must establish a flame strong enough and big enough to supply the latent heat of vaporization of the liquid fuel and continue to propagate itself.

 

My first mentor said it all: "There are no liquids capable of being burned.  You have to vaporize them first and burn the produced vapor."

[Technocrat]

Hi Umesh,

 

You said that "We have a case where the KOD is not performing, resulting in significant liquid carryover to the flare tip." Have you analysed why the KOD is not performing? Liquid carryover will be because of some reasons, few of them are listed below:

1. KOD diameter is undersized.

2. Liquid level in KOD is high (near the feed nozzle).

3. Mist eliminator (if any) is damaged (plugged or torn).

 

You can check sizing of the KOD for today's condition.

 

You can check liquid level physically in the field.

 

You can check condition of mist eliminator during shut down. You can guess the condition of mist eliminator by checking the pressure drop across it. What was the pressure drop across the mist eliminator when it was new and today's pressure drop?

 

Please tell us.

[CMA010]

I would not recommend mist eliminators in a flare service, even deflector plates have caused accidents. But besides options 1 and 2 you could investigate if an inlet device would provide better seperation.

[umeshCHE]

Dear Mr Montemayor

 

Thank you for your detailed reply.

 

It is true that liquid may not be burned without atomization. That is the reason i had specified the droplet sizes in my original query (liquid drops of upto 2000 micro meter).

 

1. API standards recommend KOD sizing considering liquid droplet separation above 300-600 micrometer size. Hence, all gas flares definitely have certain tolerance to incoming liquid droplets.

 

2. Flare vendors must have explored the limits of their flare package in terms of ability to burn larger liquid droplets. However, it is difficult to obtain this data from the vendors !!!

 

My Optimism is based on this assumption.  I am sure vendors will have a flare tip which can be installed in shorter time and will provide ability to burn higher liquid content in flare.

[gegio1960]

1. API standards recommend KOD sizing considering liquid droplet separation above 300-600 micrometer size. Hence, all gas flares definitely have certain tolerance to incoming liquid droplets.

 

That's true, but only for very limited quantities!

And why did you challenge API by specifying 2000 instead of 300-600?

Did you obtain any comment from the Vendors?

Which kind of Vendors did you ask? Did you obtain any answer from them.

 

My Optimism is based on this assumption.  I am sure vendors will have a flare tip which can be installed in shorter time and will provide ability to burn higher liquid content in flare.

 

I would say optimism is good but dreams can be easily transformed in nightmares.

In my experience special flare tips with those capabilities doesn't exist... but I'm always ready to learn new things :-)

good luck!

[Bobby Strain]

Best to start now to plan modification of the KO drum. If you provide size and flow of gas and liquid, and a dimensioned sketch of the piping, including pipe diameter, from the drum to the flare tip, maybe we can offer some guidance as to a fix. Also include level instrument locations and ranges. Also piping near the drum inlet(s). Be sure to show inlet and outlet nozzle locations and sizes. And any information on pumpout facilities.

 

Bobby

[Mach21]

have diagnose what is the reason of KOD fail to function?  what are they type of flare, LP or HP flare? 

[Babu Prasad]

 

1. Compared to installing a bigger KOD, replacing the flare tip would take less time (faster delivery of tip by flare vendor, compared to KOD vessel).

 

 

On positive side, facility is operating for  long time, so the flare gas flowrate is much lower than original design flow. This may allow for replacing the flare tip of diff spec.

 

 

As you stated, flare gas flow rate is much lower than original design flow, hence bigger KOD may not arise. Present KOD must be enough to handle your liquid carryover.   In fact, lower gas flow should not carryover the liquid as flare line from KOD to flare stack basement will be positioned inclined towards KOD to drain the residual liquid carryover in case of higher gas flow rate. Hence it could be your plant discharging more liquid into flare header and flare KOD may be running with higher level.

Liquid level must be ensured physically by opening relevant high point Level gauge  LP tapping. Some time If ADIP or caustic liquid carryout over happens along with liquid hydrocarbon , it tends to form like solid in the KOD which restrict space to settle the carryover liquid. At any point it is not advisable to burn out liquid in flare which will not be recommended by any vendor and it against operating procedure.

Edited by Babu Prasad, 15 September 2013 - 01:09 PM.

[curious_cat]

You can check condition of mist eliminator during shut down. You can guess the condition of mist eliminator by checking the pressure drop across it. 

 

Provided someone remembered to provide pressure tappings across it.