Page 82 - Coulson Richardson's Chemical Engineering Vol.6 Chemical Engineering Design 4th Edition

FUNDAMENTALS OF ENERGY BALANCES
Heat capacity data, from Volume 1, average values.
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Acetone: 25 Cto 35 C 2.2 kJ/kg K 65
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Water: 25 C to 100 C 4.2 kJ/kg K
Heat capacities can be taken as additive.
Feed, 10 per cent acetone D 0.1 ð 2.2 C 0.9 ð 4.2 D 4.00 kJ/kg K
Tops, 99 per cent acetone, taken as acetone, 2.2 kJ/kg K
Bottoms, as water, 4.2 kJ/kg K.

Q C must be determined by taking a balance round the condenser.

Q
C
H
V
V
H D = 101 kg/h
L
H
L D
V = Vapour flow
L = Reflux flow
H = Enthalpy

Reflux ratio (see Chapter 11)
L
R D D 10
D
L D 10 ð 101 D 1010 kg/h
V D L C D D 1111 kg/h

From vapour liquid equilibrium data:
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boiling point of 99 per cent acetone/water D 56.5 C
At steady state:
input D output

H V D H D C H L C Q C ,
Hence Q C D H V H D H L

Assume complete condensation.
Enthalpy of vapour H V D latent C sensible heat.