CLR reactor simulation example. A Chemical Looping Reforming (CLR) fuel reactor was simulated to illustrate the capabilities of the model. Methane and steam were fed to the reactor along with an oxygen carrier/catalyst (NiO). Catalytic steam methane reforming and water gas shift reactions as well as heterogeneous reduction of the oxygen carrier by fuel gasses were simulated. Some of the most relevant profiles are presented in Figure 9. Note that the variables were normalized by the maximum value of each variable to allow for visualization of all variables on a single graph. Figure 9 – Relevant Profiles for: Gas density (0.145-0.179 kg/m3); Total void fraction (0.868-0.874); Gas superficial velocity (4.38-5.88 m/s) and Temperature (752-800 °C) Figure 9 shows that the profiles for relevant variables in the reactor system qualitatively behave as expected: Gas density: The gas density decreases during the first 20 cm of the reactor due to the production of H2 (light gas) from the very fast catalytic steam methane reforming reaction. As the reaction system nears equilibrium and the catalytic reaction slows down, the density increases due to the conversion of H2 to H2O in the heterogeneous reduction of NiO to Ni. The decrease in temperature due to endothermic reactions also increases gas density along the height of the reactor. Total void: The total void slightly increases along the bed due to the increase of the superficial velocity caused by the steam methane reforming reaction. This reaction converts 2 moles of reactants into 4 moles of products. The change in bed voidage is very small due because this effect is cancelled out by the bubble growth rate along the bed. Larger bubbles rise faster, thus requiring a smaller void fraction to maintain the gas flux through the bed. Gas superficial velocity: The gas superficial velocity increases along the reactor bed due to the increasing of molar flux of the gaseous species created by the steam methane reforming reaction. Temperature: The temperature of the reactor decreases due to the predominance of endothermic reactions. Figure 10 – Composition profiles along the reactor height Figure 10 shows the composition profiles of the different species present in the reactor. The NiO is slowly reduced (almost at constant rate) until the end of the reactor where it tends to zero. Over the first 20 cm of the reactor length, the reforming reactions are dominant and occur very fast to produce H2 and consume CH4. After the initial 20 cm, the catalytic reaction...
