A packed tower uses packing material inside the tower to increase the surface area for gas absorption. Liquid is sprayed onto the top of the tower and flows down through the packed material while gas flows up counter-currently. This contact between the gas and liquid phases allows for absorption to take place. Bubble cap and sieve tray towers are alternatives to packed towers that use perforated plates or trays to facilitate contact between rising vapor and flowing liquid. The spacing and design of these trays is important for effective mass transfer between phases.

1. PACKEDTOWER
Struktur unitPacked Tower
• Bagian atas:
Spray untukmegubah gasinputmenjadi fase cair.
• Bagiantengah:
Packedtoweruntuk memperluaspermukaan sentuhsehinggamudahuntuk diabsorbsi
• Bagian bawah: Inputgas sebagai tempat masuknyagaske dalamreaktor.
Packed columns are used for distillation, gas absorption and liquid-liquid extraction.
The gas-liquid contact in a packed column is continuous, not stage-wise, as in a plate
column. The liquid flows down in the column over a packing surface and the vapor (or the
gas) moves counter-currently, up the column. The performance of a packed column is very
dependent on the maintenance of good liquid and gas distribution through the packed bed,
and this is an important consideration in packed column design.

2. countercurrent (gas to liquid) flow tower
BUBBLE CAPTOWER

3. Bubble cap’s flow
slotted cap on central riser
bubble cap distillationtowerthe holesineachtrayare coveredwithcapscalledbubble caps.The slots
inthese bubble capsdisperse the raisingvaporthroughthe liquidonthe tray.Each bubble caphas many
slotsand eachtray has manybubble capsto spreadup the vapor.This ensuresmaximumcontact
betweenvaporandliquidsothatmaximumheattransfercantake place.

4. Trays
Trays are a series of plates arranged vertically up the column. The liquid flows along each plate,
over a weir and then under gravity flows down a downcomer to the tray below. The height of the
weir determines the quantity of liquid held on each tray. The downcomer is taken beneath the
liquid surface on the tray below to create a vapour seal.
The vapour flows upwards through perforations in the plate (the upward flow is achieved by
maintaining a pressure drop between the bottom and top of the column). The vapour passes
through the liquid on the tray and then travels up to the tray above. The distance between each
tray is important. If the tray spacing is too large, the column becomes very high, increasing the
capital cost. If the spacing is too low, there is a risk of liquid becoming entrained with the
vapour, reducing the column effectiveness. Spacing between trays is typically around 60 cm.
Sieve tray extraction tower, arranged for light liqui dispersed

5. Sieve tray extraction tower, arranged for light liqui dispersed