Separation Processes Engineering

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Separation Processes Engineering



You are required to submit a report which will detail your design of two pieces of equipment.

Equipment 1: Design of a Plate Distillation column with side streams.

Equipment 2: Design of an Absorption Column.

For each you will be expected to clearly show each of your design steps, with clearly presented calculations and making sure you list any assumptions you make. Reference any source material that you use that is not provided in the design brief for each piece of equipment.


Coursework layout/presentation

You should have a title page clearly indicating your coursework title, your name, UoB number and the module. You should have an index showing what is in the report. The font type should be either Times New Roman or Arial with a size of 12pt. Your lines should be double spaced and paragraphs should be of appropriate sizes i.e., not too short and not too long. All your figures, tables, charts etc. should of a high standard and should be labelled clearly and referred to in the text. Make sure that your graphs, figures etc are clearly legible.

Put your references on a separate page at the end.





Separation Processes Engineering Course Work

Part 1: Plate distillation column with side streams

  1. A mixture of ethanol and water containing 0.15 mole fraction ethanol, is separated in a fractionating column to give a top product containing 0.8 mole fraction ethanol and a side stream product containing 0.55 mole fraction ethanol. The aqueous waste is to contain 5.2 mole per cent of the alcohol fed to the column and has a concentration of

0.01 mole fraction ethanol. The feed is supplied as boiling liquid and a reflux ratio of

4.0 is used. Carry out a mass balance around the column and Determine:

  1. a) The number of theoretical plates required in the column
  2. b) The feed plate and side stream plate locations.

The ethanol equilibrium data is given below:


x 0.019 0.072 0.124 0.166 0.261 0.397 0.573 0.676 0.747 0.894
y 0.170 0.389 0.470 0.509 0.588 0.612 0.684 0.738 0.782 0.894


Details of how the operating line equations, for the three sections of the column, derived from first principles must be shown.

  1. 2. Use Aspen Plus to carry out the following simulation:

A distillation column is required to separate a liquid feed containing 25 mole % benzene and 75 mole % toluene to give a top product containing 90 mole % benzene and a bottoms product containing 4 mole % benzene. A reflux ratio of 2.50 is to be used and the feed enters at its boiling point. The feed, re-boiler and condenser pressures are 2.0 bar, 2.2 bar and 1.8 bar respectively.

Assuming the plates to be 100% efficient, calculate the composition of the liquid mixture on the third plate (counting from the top of the column). Assume a feed flow of 100 kmol/hr and feed temperature of 25 °C. You should provide printouts of the

Aspen Plus results in you report.


Part 2: Gas Absorption column

Ammonia is to be recovered from an air/ammonia mixture, containing 12% by volume ammonia, by scrubbing with clean water in a packed column. The aim is to recover at least

95% of the ammonia. The operation is to be done counter-currently at 1 bar pressure and

25 °C using randomly packed 1” rashing rings.

The mass flow rate of the gas mixture entering the column is 2 kg/s.

Under these operating conditions the following has been determined.

KGa = 0.05 kmol/

The equilibrium relationship is given by:

p = 0.2x

where p = partial pressure of ammonia in gas phase (bar)

x = concentration of ammonia in liquid phase (mole fraction)


1) The diameter of the column. Assume a flooding condition of G = 0.6Gf

2) Concentration of ammonia leaving in the liquid phase at the bottom of the column.

3) The height of packing required using the following methods:

  1. a) Graphical integration using the complete design expression
  2. b) Using the design equation for a Logarithmic mean driving force.