1. Packed Columns - continuous vapor/liquid contacting Grids
Random packing
Structured packing

2. Common Packings
- fabricate from
ceramics, plastics,
metals

3. Packed vs Trayed Columns
Packed Columns
Trayed Columns
Ulrich, 1984

4. Vessels are sized based on:
What do you think will limit the size of a:
Superficial velocity, Ut=Umax
Pressure drop
Residence time tres
Biofilter
Seperator to remove oil droplets from wastewater
Spray tower
Cyclone

5. Packed Column Design - Design for pressure drop
Absorption to 400 Pa/m
Distillation to 600 Pa/m
Vacuum distillation Pa/m
- Set velocities from pressure drop and flooding curves
G = gas flux, kg/s/m2
L = liquid flow, kmol/s
Ml = liquid MW
At = column area
l = liquid density kg/m3
g = gas density kg/m3
Cf = packing constant (see Fig)

6. Figure 4-32, Ulrich G = gas flux, kg/s/m2 L = liquid flow, kmol/s
Ml = liquid MW
At = column area
l = liquid density kg/m3
g = gas density kg/m3
Cf = packing constant (see Fig)
Figure 4-32, Ulrich

7. Packed Column Sizing Constraints
Flooding/pressure drop curves limit velocity
Velocity sets diameter
Height set by mass transfer
Height = Height of packing + Height of internals+Liquid surge at bottom of column
Height of packing = # theoretical stages/HETP
HETP=Height equivalent to a theoretical plate
L/D guidelines are mainly for seperators

8. HETP For distillation in packed columns
For D>0.5m; HETP=0.5D0.3
For gas absorption, allow more packing
For D>0.5m; HETP=D0.3
For small towers (both distillation and absorption)
For D<0.5m; HETP=D
This includes the efficiency.