Difference between Vane Pack & Wire Mesh Demister Pad 2

[Venkatachalam Ponnusamy]

Can anyone explain about the application & major difference between Vane Pack & Wire Mesh Demister Pad.
Whether both are used for Gas Applications ? I understand that the Demister Pad is used to remove the liquid droplets from the Gas.
Your advice will be appreciated a lot

 

[austsa]

Both are used to filter out liquid droplets present in a gas stream. Suitability depends on your needs, and can also be used in series. Sulzer Chemtech has useful basic info, just google Sulzer Chemtech separation technology.

 

[LittleInch]

For me a vane pack is less pressure drop and intended to drop out bigger droplets / liquid quantities.

A demister pack is what it says - it de mists. However to avoid the droplets getting simply blown through the pad, you need either a low velocity or large area to get your low velocity.

Both are gas applicable - I would normally expect to see a vane pack on the inlet and a demister on the outlet.

Look up the famous shell shoepentoeter

https://www.sulzer.com/en/shared/products/shell-schoepentoeter-and-schoepentoeter-plus

Now THAT's a vane pack and a half...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[austsa]

A schoepentoeter spreads the high velocity gas flow (coming from the inlet) evenly across the cross-section of the vessel. Without an inlet device, one portion of the filter device would have to filter much more gas than other portions of the filter device, thereby reducing overall efficiency.
A vane pack is a unit with many layers of steel with many zig-zag creases. Vane pack forces the gas stream to change direction multiple times. Momentum of droplets are higher (heavier) and are intercepted by the vanes. Intercepted liquids run down the pack to a drain, and resultant gas is drier.

 

[Venkatachalam Ponnusamy]

@ Austa and @LittleInch

Thanks and really appreciate for your prompt responses and it helps me.
1. Understand from your response that the Vane pack is used to remove the bigger/heavier droplets of liquids from the Gas at the Inlet of Vessel.
2. And Demister is located at the Outlet Nozzle of Gas to filter the droplets in Micro level.
3. Understand that Stringent Performance Guarantee of Gas can be met through Demister Pad only (like <10 microns liquid droplets at the outlet).

Also i have come across using the Coalescer Pack in Three Phase Heater Treater Separator for Liquid application (to Separate Oil/Water/Gas). Understand that the Coalescer Pack is nothing but Vane Pack ? correct me if i am wrong. I also would like to know how Coalescer Pack works on Liquid application in Heater Treater (Three Phase) Separator.

Request for your response..

Regards,
Venkat

 

[austsa]

Each device has its advantages and disadvantages.

Coalescers are polymeric material that comes in long cylindrical cartridges. Filter vessels can have one or many cartridges. Essentially, they combine very fine droplets together creating larger droplets which run or drip down to a sump/drain. They're useful when outlet gas needs to be very dry. When designing a coalescer filter, there's always a key decision to be made: should the coalescer filter orientation be vertical (more efficient filtering but usually more expensive capex or opex), or horizontal (cheaper capex & opex but less efficient filtration).

 

[georgeverghese]

Vane packs are used for coarser V/L separation in fouling environments. Demisters enable lower liquid entrainment in the exit gas stream in clean to minimally fouling applications. Vane packs are available as single pocket or double pocket, and choice depends on required efficiency in V/L separation.

Other more efficient types of V/L separation devices are licensed by major OpCos, and may be offered to the general public at a price through 3rd party licensees.

Coalescers are for either V/L separation or L/L separation. Cross flow corrugated plate packs (L/L sep), knitted wire mesh assemblies(L/L sep) and fibrous cartridge type candles( for V/L or L/L) are all loosely called coalescers. Cross flow plate packs in L/L separation service are less prone to blockage in fouling environments. Contact surfaces on these devices are either hydrophilic or hydrophobic type.

 

[Venkatachalam Ponnusamy]

@georgeverghese, @austsa,

Thanks & will appreciate for your valuable time.