ExamC

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CRE – 03.02.15 - Exam C 096116 Chemical Reaction Engineering 3 February 2015 Family name _________________________________________________ First name _________________________________________________ ID number _________________________________________________ Signature _________________________________________________ Please, consider that the sum of percentages of proposed exercises (4) is equal to 110%. This means that the maximum mark you can reach is 33. Remember to write on the top of each sheet you submit: your name, ID number, and signature. Use of mobile phones and internet connection is not allowed. 1. Adiabatic CSTR with reversible, exothermic reaction (40%) The elementary, exothermic, reversible gas phase reaction 𝐴𝐴→ 2𝐵𝐵 𝑟𝑟= 𝑘𝑘�𝐶𝐶𝐴𝐴− 𝐶𝐶𝐵𝐵 2 𝐾𝐾𝑒𝑒𝑒𝑒 � has to be carried out adiabatically. Pure A is fed at a rate of 𝐹𝐹𝐴𝐴 0 = 3 𝑚𝑚𝑚𝑚𝑚𝑚/𝑚𝑚𝑚𝑚𝑚𝑚, temperature of 𝑇𝑇0 = 100°𝐶𝐶, an d concentration of 𝐶𝐶𝐴𝐴 0 = 0.03 𝑚𝑚𝑚𝑚𝑚𝑚/𝑚𝑚. The equilibrium constant is a weak decreasing function of temperature, but, for simplicity, we assume it constant: 𝐾𝐾𝑒𝑒𝑒𝑒= 25 ∙ 10−3 𝑚𝑚𝑚𝑚𝑚𝑚 𝑚𝑚 a) What is the adiabatic equilibrium temperature and conversion? b) If you know that the kinetic constant (measured in min-1) is a function of temperature (measured in K): 𝑘𝑘= 24 𝑒𝑒−2100 𝑇𝑇 what is the CSTR volume necessary to achieve 80% of the adiabatic equilibrium conversion? Reaction heat at 100°C Specific heats ∆𝐻𝐻� 𝑅𝑅= −3500 cal/mol 𝐶𝐶𝑃𝑃𝐴𝐴� = 5 cal/mol/°C 𝐶𝐶𝑃𝑃𝐵𝐵� = 2.5 cal/mol/°C 2. Isothermal catalytic reactor without diffusion limitations (30%) The catalytic reaction 𝐴𝐴→ 𝐵𝐵 to be carried out in a flow reaction system (PFR and/or CSTR) has the following rate law: 𝑟𝑟= 𝑘𝑘𝐶𝐶𝐴𝐴 (1 + 𝐾𝐾𝐴𝐴𝐶𝐶𝐴𝐴)2 1 CRE – 03.02.15 - Exam C where 𝑘𝑘= 1 𝑚𝑚𝑚𝑚𝑚𝑚−1 and 𝐾𝐾𝐴𝐴= 1.5 𝑑𝑑𝑚𝑚3/𝑚𝑚𝑚𝑚𝑚𝑚. The entering concentration of A is 𝐶𝐶𝐴𝐴…