Chlorobenzene from Benzene and Chlorine

Design of a Chlorobenzene Distillation Unit

Design Tasks

Process Design•Material Balance Around the whole process • Energy Balance around the whole process• Construct Input-Output Diagram, Functional

Block Flow Diagram, and Process Flow Sheet for the whole plant.

Material Balance

The ‘Onion Skin’ Diagram for Organization of a Chemical Process and Hierarchy of Analysis

Revisions are made at the Reactor Section

Material Balance

Reactor Section• 2 continuous stirred tank reactors• Kinetics:

C6H6 + Cl2 = C6H5Cl + HCl

C6H5Cl + Cl2 = C6H4Cl2 + HCl

Material Balance

Reactor Section• Change of basis, concentration term is

used rather than mole fraction• Similar Approach: from component

material balance, the residence time for the optimum monochlorobenzene concentration is determined.

Material Balance

Reactor Section• Residence time,

• Concentrations of the components can now be obtained using the residence time and the component balances• Amount of Chlorine gas supplied is

obtained from stoichometry

Material Balance

Reactor Section•Major Revision: Some of the benzene

would be retained in the HCl vapor stream that leaves the first reactor•Monochlorobenzene and para-

Dichlorobenzene are similar compounds and are likely retained in the liquid phase compared to benzene

Material Balance

Reactor Section• Peng-Robinson EOS Mixture Program was

utilized to determine the VLE data of Benzene and HCl• Binary Interaction Parameter,

• Concentration of Benzene and HCl in the liquid and vapor phase can be determined

Material Balance

Reactor Section• Concentration and consequently the

mole/mass fractions of the components of the liquid stream leaving the first reactor can be determined.• In the second reactor, it is assumed that

there would be negligible benzene in the HCl vapor stream since there are only small amounts of benzene in the liquid stream

Material Balance

Reactor Section• HCl dissolved in the product liquid stream

is specified, 1.5 % by weight HCl• Concentration of the liquid product stream

from the second reactor can be determined through component balances• Actual amounts of the various streams in

the reactor section is yet to be determined

Material BalanceChlorobenzene Column

Design Tasks

Chemical Engineering Design• Prepare a sieve-plate column design for the

chlorobenzene column and make dimensioned sketches showing details of the plate layout including the weir and downcomer

Design Tasks

Mechanical Design• Estimate the shell thickness, the positions

and sizes of all nozzles, and method of support for the plates and column shell. Make a dimensioned sketch suitable for submission to a drawing office

Design Tasks

Process Safety and Control• Indicate the safety measures required for

this plant bearing in mind the toxic and inflammable materials handled.• Design a process control system for the

chlorobenzene distillation unit