Ive been struggling to solve ii, im not sure how to model a mass balance onto GAMS, any help would be appreciated.
Ammonia is an important industrial chemical that is manufactured by the Haber-Bosch process by reacting hydrogen and nitrogen at very high temperature (500-600°C) and pressure (800-1000 atm) by using a suitable catalyst (see Figure 1). Ammonia is also being considered as an energy vector for pushing the drive towards a low-carbon economy. In the Haber-Bosch process not all of the hydrogen and nitrogen entering the reactor is converted into ammonia and therefore a recycle is required to recover the unreacted hydrogen and nitrogen and recycle these back to the reactor. The nitrogen used in the process is obtained from the atmosphere and therefore the feed contains a small amount of inert gases, which for our purpose we will assume consist just of argon. Since argon does not participate in the reaction, a purge is required to prevent its build-up in the recycle stream. The process flowsheet for ammonia production is shown below. The reaction takes place in the Reactor, most of the ammonia thus produced is separated in Separator-1 and sold as Product (stream 4). The output (stream 5) from Separator-1 goes into Separator-2 where Purge (stream 7) and recycle (stream 6) are the outputs. The recycle (stream 6) is mixed with the fresh feed (stream 1) in the Mixer before being fed to the Reactor.
The feed stream consists of: (kmols hr-1)
N2 2457
H2 7516
Ar 27
3H2 + N2 → 2NH3
(extent of reaction) ν = 2200 kmol hr-1
Separator 1
Use the following split fractions for stream 3 going to stream 5:
αN2 = 0.85 αH2 = 0.85 αNH3 = 0.1 αAr = 0.9
Separator 2
Use the following split fractions for stream 5 going to stream 6:
αN2 = 0.95 αH2 = 0.95 αNH3 = 0.1 αAr = 0.1
i. Write the mass balance for this problem and submit it as a part of the report.
ii. Equation Oriented Process Flowsheeting using GAMS as a modelling tool: Formulate this problem in GAMS and solve it using the CNS solver.