Exercise 4 Text

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1 Department of Energy Politecnico di Milano Via Lambruschini 4 – 20156 MILANO Exercises of “Fundamentals of Chemical Processes” Prof. Gianpiero Groppi Exercise 4 Outlet temperature and composition of a WGS reactor (Stage I) for the conversion of CO. The gas stream that exits the second stage of a Reformer supplied with air is sent to a two-stage reactor for the conversion of CO, where the following reaction occurs (Water Gas Shift, WGS): CO + H2O → CO2 + H2 With reference to the first stage of the conversion of CO, it can be assumed that the reactor is adiabatic and that the outlet gases reach the thermodynamic equilibrium composition 20°C above the exit temperature T OUT. Determine the temperature TOUT and the composition of the exit composition. DATA: Stream 1: P = 30 atm T = 360°C Stream 2: P = 30 atm TOUT = ? Hypothesis: Ideal gas WGS is at the chemical equilibrium Adiabatic reactor 2 Species Flow Rate (Nm 3/h) % Vol. Dry Basis H2 56.36 N2 22.24 CO 12.56 CO2 8.27 Ar 0.27 CH4 0.3 H2O 73411 dry 120264 100.00 Totale 193675 3 Solution The problem asks for the estimation of the composition and the temperature T OUT of the gas stream that exits the reactor. In order to solve for these two unknowns, two equations must be written, namely the one derived from the equilibrium condition at the outlet of the reactor, and the enthalpy balance on the adiabatic reactor. It is convenient to write the mass balance by following the extent of reaction approach. The extent of reaction λ is defined and the outlet molar gas streams are determined as a function of the incoming ones, assuming a basis of 100 mol/h of incoming dry gas. Species Flow Rate (Nm 3/h) n in (mol/h) n out (mol/h) H2 56.36 56.36 +  N2 22.24 22.24 CO 12.56 12.56 -  CO2 8.27 8.27 +  Ar 0.27 0.27 CH4 0.3 0.3 H2O…