3 replies to this topic

[Mathi]

I am a little bit confused on the below paragraph of API STD 521. Please pinch in your opinions on this regard. 

 

"Liquid droplets 300 μm and larger may drop out of the gas stream at less than 2 m/s. If liquids are not drained from the system, flare flows with gas velocities exceeding about 3 m/s or 4 m/s can entrain liquid droplets up to 1000 μm in size. Liquid droplets exceeding 1000 μm can readily lead to burning rain regardless of flare type. Burning rain can occur at smaller droplet sizes for some flare types."

 

My queries are the following.

 

In KOD sizing, should the gas velocity in the KOD be kept at less than 2 m/s to enable liquid droplets larger than 300 microns to separate despite having gas residence time greater than liquid droplet fall time?

 

Are there any other reference articles or studies supporting the above statement of API STD 521?

[Bobby Strain]

API 521 has never been a good guide. You can visit my website, just Google my name, and use the sample horizontal separator program you can access from the link on the home page.

 

Bobby

[Mathi]

Bobby

 

Thank you. Your online calculations was useful. However, I am unable to adjust the liquid droplet size. Can you please explain the logic behind "Max Vapor K recommended" and "Max. Vapor X flow velocity Recommended"? 

 

It is my understanding that "Max vapor k recommended" is based on souder brown equation. I am have no idea regarding max. vapor x flow recommended. It will be helpful if you can elaborate.

[Bobby Strain]

You must select the flare KO drum where you see the Process Separator displayed. You can change the droplet size. The maximum values are used in the sizing routine. These limits will always give you a separator/KO drum that is not too small. This is the stuff that the API procedure doesn't address explicitly.

 

Bobby

Edited by Bobby Strain, 28 December 2017 - 03:47 PM.