chiemny trays

[kakaie]

i would like to know what the purpuse of using chiemny trays in distillation towers is? forexample in a demethanizer we use such trays at the reducer of the tower.

 

[25362]

Heat-integrated cryogenic gas plant demethanizing columns use chimney trays as total liquid trap out trays to enable feeding side reboilers. The reboiled V/L mix is flashed below the chimney trays. The chimneys allow vapor to pass through without contacting the liquid.

 

[MaNaTMoS]

Dear Kakaie,

chimney trays are known as "liquid collectors", which means they are mostly used as product side draw-off or pumparound draw-off trays. They are also employed in packed towers as liquid and vapor distributors (in this arrangement tray deck has certain number of holes, in order to ensure proper liquid "dripping" distribution). In my unit (ADU) chimney trays are No.3 (top pumparound draw-off tray) and 21 (diesel product and diesel pumparound draw-off tray). In vacuum distillation unit, which has structured packings, chimney trays are employed as liquid collectors-vapour distributors - located beneath each segment of packing. Important parameters when designing chimney tray are: chimney height, hat height, number of chimneys, pressure drop accros chimney, and overflow pipe installation (to avoid liquid in-leakage and packings flooding, if pump trips off), etc.
This subject is rather complex, maybe you could try searching on the internet if interested in some particular details.

Hope this helps a little bit.
MaNaTMoS