Determine the molar flowrate and molar composition of the

Question

Analysis of chemical engineering processes (ANCHEM)

Question 1

Ammonia (NH₃), a useful industrial chemical, can be produced by the following chemical reaction:

N₂ + 3H₂ → 2NH₃

The schematic diagram below depicts the production process of ammonia. This plant is able to achieve 92% overall conversion of Nz. The fresh feed to the process (stream 1) contains 23.5 mol% N2, 75.7 mol% H2 and 0.8 mol% methane (CH4). CH4 is an inert in the feed that does not participate in the reaction. The fresh feed is mixed with a recycle stream (stream 7) to produce the feed to the reactor (stream 2). It is known that the recycle stream contains 5.6 mol% CH4 and that the reactor feed stream (stream 2) contains 4.7 mol% CH4. The reactor outlet steam (stream 3) goes into a condenser which condenses most (but not all) of the ammonia produced in the reactor. The gas stream leaving the condenser (stream 5) contains N₂, H₂, CH₄ and uncondensed ammonia vapour. Use a basis of 100 kmol/h of the fresh feed stream.

Determine

(a) the molar flowrate and molar composition of the purge stream (stream 6);

(b) the production rate of liquid NH₃ (kg/h);

(c) the mass flowrate and mass composition of the recycle stream (stream 7);

(d) the single-pass conversion of N₂.