Exercise 6 Text Adiabatic Partial Oxidation reactor

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Department of Energy Politecnico di Milano Via Lambruschini 4 – 20156 MILANO Exercises of “Fundamentals of Chemical Processes” Prof. Gianpiero Groppi Exercise 6 Estimation of the temperature and the composition at the exit of an adiabatic reactor for the partial oxidation of CH4 The partial oxidation of CH4 is carried out in an adiabatic reactor: CH4 + ½ O2 → CO + 2 H2 Calculate the composition and the temperature of the gas at the exit of the reactor, assuming that equilibrium conditions are reached. CO, H2, H2O and CO2 are present among the products while O2 is absent. Data: Stream 1: P = 30 atm T = 500°C Stream 2: P = 30 atm Tout = ? Hypotheses: Thermodynamic equilibrium Ideal Gas Adiabatic Reactor Species Flow Rate (Nm3/h) CH4 1 O2 0.6 H2O 1  TTG SRR  25.60537170 , cal/mol 600 K < T < 1500 K  TTG WGSR  71.785140 , cal/mol 600 K < T < 1500 K Solution The problem asks for the estimation of the composition and the temperature Tout of the gas stream at the exit of the partial oxidation reactor. To solve the problem, the material balances and the enthalpy balance must be coupled, assuming that the reactor is adiabatic and that the gas reaches the thermodynamic equilibrium. 1 mol/h of incoming CH4 is chosen as the basis for the material balances. Considering the number of the species involved in the process (NS = 6) and the number of the atomic species (NA = 3), the number of independent reactions that are required to define the solving system are: 36 NANSNR 3 reactions are required to write the material balances. For each of these reactions, it is possible to define an extent of reaction λi. The following reactions are chosen: OHCOOCH 2224 2  1 complete combustion COHOHCH  224 3 2 steam reforming OHCOOCH 2224 2  3 WGS The choice of the…