Download Assignment 1 – Chemical Design PDF

TitleAssignment 1 – Chemical Design
TagsDistillation Transparent Materials Phases Of Matter Phase (Matter) Cracking (Chemistry)
File Size632.9 KB
Total Pages24
Document Text Contents
Page 13

Distillate temperature = -23.15 °C

Bottom temperature = 95.85 °C

Average column temperature =





Therefore, average column temperature = 36.35 °C

Since the distillate is taken as saturated vapor and bottom product is taken as saturated liquid,

only latent heats of vaporization and condensation counts for the energy balance or Reboiler

and condenser heat loads.

Condenser Heat Load



Where, λL = Latent heat of liquid mixture which is at equilibrium with distillate vapor

L = Liquid flow rate of rectifying section (only this part is condensed while product is taken

as vapor)

Latent heat of a mixture can be calculated as,



From the calculations, λL = 487052.212 J/kg

LW = Liquid mass flow rate in rectifying section = 224622.1158 kg/day

Therefore,

Condenser Heat Load = 109402.698 MJ

Reboiler Heat Load

In similar manner, Reboiler heat load is calculated. Here Latent heat of vaporizing vapor and

its mass flow rate is taken for calculation.

From the calculations, λL = 503139.3 J/kg

LW = Vapor mass flow rate in stripping section = 929639.3296 kg/day

Therefore,

Condenser Heat Load = 467738.0815 MJ

Page 23

AC = 1.1233 m
2

Ad = 0.1348 m
2


Aa = 0.8537 m
2

Ah = 0.08537 m
2

Stripping section

Same procedure of calculation for rectifying section was used. But the notification is used as

( )’ for the convenience of identification.

Therefore the calculated parameter values are as follows,

From the graph for the relationship of Flow parameter vs. Flooding vapor velocity, (Vol 6,

p567)

K1’ factor = 0.076, for a tray spacing of 0.6 m.

Uf’ = 0.3396 m/s

Assume 70% of flooding is maintained in the tower

Then, Ua’ = 0.2377 m/s

Vg’ = 0.3727 m
3
/s

An’ = 1.568 m
2

AC’ = 1.7818 m
2

Ad’ = 0.2138 m
2


Aa’ = 1.3542 m
2

Ah’ = 0.1354 m
2



Column diameters

Rectifying section

Once the column cross sectional area is known, the diameter of the column can be calculated

as follows.

Page 24

Where,

DC = Column diameter

The column diameter for the rectifying section,

DC = 1.1959 m

Diameter of the column is greater than 1 m. Therefore the tray spacing of 0.6 m is acceptable.

Stripping section

Using the same equation, the diameter of the stripping section (DC’) is found to be,

DC’ = 1.5062 m

The diameter of the stripping section is greater than 1 m. Therefore the tray spacing of 0.6 m

is acceptable.

Column Height

Column height can be obtained by,



H = Column height

Na = Number of actual trays = 42

Tray spacing = 0.6 m

Therefore, H = 25.2 m

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