Flare's, Heat Attenuation, and Water Injection

[DM2]

I'm wondering if anyone out there has some good information on methods for reducing the heat radiation from a Flare. I've read a few articles regarding heat reduction by means of injecting water direction into the combustion zone of the flare, but no information with regard to the water flow rate based on any flame data or size, or what and how the heat reduction may be calculated.

Can anyone point me to some good information on the subject?

Regards,
Dan Marr

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."

 

[Buchi]

Hi DM2,

One of the best ways to reduce the heat radiation on the personnel is to assist the flare tip with high pressure fluids like gas injection, water injection, steam injection etc. this is quite common in Low pressure conventional tips or so called open pipe tip which are usually subsonic at peak flaring rate. burning can be smoky with high radiation under this condition hence the need to use assist fluids as identified above. offcourse, increasing the stack height is another way of taking away the hot radiant heat from the personnel.

This is a different ball game for High Pressure Sonic tips that allow high pressure drop across the tip and therefore ensures a high air entrainment and good mixing which allows for smokeless burning and reduced thermal radiation. although more expensive and more maintenance requirement.

if you want to know the amount of assist fluid required, this is usually a function of the tip in question and the amount of flare gas being passed through the tip. Flowrate of assist fluid is usually a ratio of the flared gas flowrate.


Buchi

 

[DM2]

Buchi,
Thanks for the reply. The flare tip is a Sonic tip.

Do you have, or know of, and papers on the subject of "...assist fluid required..."?

You say that it is a function of the "...tip in question...", but I'm would guess that it is more about the flow rate. One recommendation we received was 330 gpm for a flow of 80 MMSCFD flow rate.

Any reference publications you may have would be appreciated.

Regards,
Dan Marr

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."

 

[Buchi]

Hi DM2,

it is not just about flowrate. API 521 explicitly states that the amount of steam required is primarily a function of the following;

1. flare gas composition

2. flowrate

3. steam pressure

4. tip design

since tip design is a factor, that was why i suggested you touch base with your Tip vendor because most times, tips are proprietary.

well, I will advice you to read ANSI/API standard 521 fifth edition, January 2007, page 85. it seems to discuss this subject in details with facts and figures.table 11 in page 87 even gives you numbers for steam required for assist. This is the very latest version of API RP 521.

a foot note in this table 11 also advised that you consult your tip vendor for steam required rate.

In tip design, you can do too much without vendors information.

i hope that helps.



Buchi