Question 10.2: 96,000 lb/h of a distillation bottoms having the following c...
96,000 lb/h of a distillation bottoms having the following composition will be partially vaporized in a reboiler:
Component | Mole % | Critical Pressure (psia) |
Propane | 15 | 616.3 |
i-butane | 25 | 529.0 |
n-butane | 60 | 551.1 |
The stream will enter the reboiler as a (nearly) saturated liquid at 250 psia. The dew-point temperature of the stream at 250 psia is 205.6ºF. Saturated steam at a design pressure of 20 psia will be used as the heating medium. The reboiler is to supply 48,000 lb/h of vapor to the distillation column. The reboiler feed line will be approximately 23 ft long, while the vapor return line will have a total length of approximately 20 ft. The available elevation difference between the liquid level in the column sump and the reboiler inlet is 9 ft. Physical property data are given in the following table. Design a kettle reboiler for this service.
Property | Reboiler Feed | Liquid Overflow | Vapor Return |
T (ºF) | 197.6 | 202.4 | 202.4 |
H (Btu/lbm) | 106.7 | 109.9 | 216.4 |
C_P (Btu/lbm ·ºF) | 0.805 | 0.811 | 0.576 |
k (Btu/h · ft ·ºF) | 0.046 | 0.046 | 0.014 |
μ (cp) | 0.074 | 0.074 | 0.0095 |
ρ (lbm/ft³) | 28.4 | 28.4 | 2.76 |
σ (dyne/cm) | 3.64 | 3.59 | – |
Molecular weight | 56.02 | 56.57 | 55.48 |
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