2. Methanol is produced by reacting a mixture of carbon dioxide and carbon monoxide with

hydrogen over a catalyst. The reactions are:

CO(g) + 2H₂(g) → CH₂OH(g)

CO₂(g) + 3H₂(g) → CH3OH(g) + H₂O(g)

The composition of the fresh feed is 14 mol % CO2, 14 mol % CO, 70 mol % H2 and 2 mol % CH4.

The fresh feed is mixed with a recycle stream before entering the reactor. The single pass

conversion of CO and CO2 are 20% each. The product gases are cooled to condense out all the

water and methanol. All the unreacted gases are then recycled. Part of the recycle stream is

purged to keep the content of the inert CH4 in the reactor feed to 5 mol %.

It is desired to produce 100 mol/s of methanol.

a) Sketch the Process Flow Diagram (PFD and indicate all the components of each stream.

(18 marks)

b) Determine the following:

i) molar flow rate of fresh feed,

ii) molar flow rate of the stream at the reactor inlet,

iii) molar flow rate and composition of the purge stream.

End of paper

(32 marks)