COLUMN DIAMETER

1. Flooding velocity

Liquid vapour flow factor at top and bottom

where Lw = liquid mass flow-rate, kg/s, Vw = vapour mass flow-rate, kg/s.

K1 (top and base) from Fig.(11.27)

Corrected K1 values (σ/0.02)0.2 * K1(top and base)

Where σ is the surface tension (value from chart)

2. Vapour velocity3. Area at top and bottom4. Find Column diameter

DESIGNING OF PLATE

1. Liquid flow pattern Fig 11.28

2. Column area Ac

3. Downcomer area Ad (assume 12%)4. Net Area An

5. Active area Aa

6. Hole area Ah

7. Lw/Dc from Fig 11.31

8. Lw

9. Assume suitable weir height (hw), hole diameter and plate thickness.

CHECK WEEPING

1. Maximum liquid rate (kg/s)2. how max

how = height of liquid over weir or liquid crest.ρL = liquid density at the base.

3. Minimum liquid rate (assume 70% of max)4. how min

5. Minimum design vapour velocity

dh = hole diameter (mm)For K2 refer fig. 11.30.

ρv = vapour density at the base.

6. Actual minimum vapour velocity = min vapour rate/Ah > uˇh

PRESSURE DROP CHECK

ht = hd + (hw +how) + hr

ht < assumed pressure drop

Dry plate pressure drop

1. Maximum vapour velocity through holes2.

uh = maximum velocity through holes.ρv and ρL =densities at the base.hd (in mm of liquid)

3. Refer fig 11.34 to get C0

Residual head (hr)

ρL = liquid density at the base.

CHECK ENTRAINMENT

Fractional entrainment ψ = entrained liquid/gross liquid flow

Refer fig 11.29. use FLV at the base.

Ψ <0.1.