6 replies to this topic

[Qzymandias]

Does anyone know of a place to find direction on sizing a baffle for a knockout drum? The API section on knockout drums covers sizing the drum perfectly well, but neglects even to mention baffles.
Thank you,

Ozy

[kkala]

Googling "knock out drum baffles" discloses interesting information, including following.
1. "In older plants, inlet deflector baffles were installed in some knockout drums. The idea was to direct the inlet jet downward and thus to improve the effectiveness of separation. Such a configuration causes a large pressure drop and in many cases interferes with entrainment separation because of breaking coalesced droplets into smaller ones. There is no evidence that an inlet deflector improves performance".
From http://www.amistco.c...ish/tech105.htm.
2. Some guidelines for baffles / baffle plates, understood for vertical KO drums.
http://mycommittees....20Internals.pdf.
3. "Various inlet devices are available to improve the vapor / liquid separation. Among others the following inlet devices may be installed: a deflector baffle, a slotted tee distributor, a half-open pipe, a 90 ° elbow, a tangential inlet with annular ring, a schoepentoeter (for the latter see http://www.sulzerche...808_read-15612/).
For vertical drums, preferably a deflector baffle or a half open pipe shall be selected. In case of a slug flow regime in the inlet piping, or if a high liquid separation efficiency is required, a tangential inlet nozzle with annular ring can be used. However, in case a high liquid removal efficiency is required, the application of a wire mesh demister is preferred.
For horizontal drums normally a 90° elbow or a slotted diverter is installed. In some cases a submerged inlet pipe is installed, but this shall not be done in the case of a two-phase feed.
Normally the selected inlet device for a horizontal drum shall be:
- a 90° elbow or a slotted diverter in case of an all liquid or vapor-liquid feed
- a submerged pipe when the feed is a subcooled liquid and the mixing of liquid and blanket gas is to be minimized.
- two 90° elbow inlets in case of high vapor loads".
http://www.red-bag.c...sel-sizing.html.
4. "Another method for using a vertical drum is to use a tangential inlet. With a tangential knock out drum, the gasses enter and spin around the wall of the vessel. While spinning the fluidic friction of the gas along the wall will "scrub out" much of the entrained liquid. Baffles are also used in a vertical drum to disrupt and slow down the gas prior to exit".
http://www.alliedfl...-out-drums.html.
5. More info can be obtained from google.

Edited by kkala, 02 December 2011 - 04:24 PM.

[ankur2061]

Refer the attached sketch for a deflector plate (baffle) at the gas outlet of a Horizintal Knockout Drum.

Regards,
Ankur.

Attached Files

•  Deflector_Plate_KOD.pdf   66.98KB   384 downloads

[Qzymandias]

Kkala,
Thank you for your input, it brings me nearer the conclusion that there simply isn't a standard on designing the baffles. It seems that, knowing the process and the knockout's place in it, a designer would make a baffle catered to it.

Ankur,
If you wouldn't mind could you please post in the thread what your diagram says on the bottom? For me at least, only the first line of text is readable.

Thank you both for your time and attention,

Ozy

[ankur2061]

Ozy,

It says "Deflector Plate (baffle) at least 5 mm thick is recommended". The bold and underlined portion has got cut.

Regards,
Ankur.

[Qzymandias]

Thanks again Ankur.

Edited by Qzymandias, 07 December 2011 - 10:32 AM.

[breizh]

Let you get a copy of this book :
Gas-liquid and Liquid-liquid separators by Maurice Steward and Ken Arnold (gulf equipment guide)

Hope this helps

Breizh