Combined Partial Oxidation and Carbon Dioxide Reforming Process: A Thermodynamic Study

Problem statement: CO 2 reforming is one of the methods to utilize a greenhouse gas to produce syngas, an important feed for methanol and Fischer-Tropsch synthesis. However, CO 2 reforming is strong endothermic reaction requiring large amount of supplied energy. Partial oxidation, an exothermic reaction, is combined with CO 2 reforming to serve the energy requirement. Thus, the optimum ranges of O 2 and CO 2 fed to the process corresponding to feedstock are needed to find. Moreover, one of the most important problems found in this process is solid carbon formation. Therefore, the operating range in which the carbon formation can be avoided is also required to study. Approach: In this study CH 4 was used as feedstock. The optimum rage of O 2 and CO 2 fed to the process was found by using thermodynamic equilibrium method based on minimization of Gibbs free energy. The Lagrange multiplier method was conducted to form the equations and they were solved by the Newton-Raphson method. The solid carbon formation zone was also simulated. Results: The simulation showed that higher reaction temperature caused higher CH 4 and CO 2 conversions. Syngas production increased with increasing temperature. Operating the process with high temperature or high O 2 /CH 4 and CO 2 /CH 4 rations could eliminate solid carbon formation. Increase of O 2 /CH 4 ration higher than 0.1 led decreasing syngas while increase of CO 2 /CH 4 ration caused increasing H 2 and CO. However, when CO 2 /CH 4 ration was higher than 0.85, increasing CO 2 /CH 4 ration showed insignificant change of syngas concentration. Conclusion: The combined partial oxidation and CO 2 reforming of method should be operated with reaction temperature of 1050 K. The optimum range of CH 4 :CO 2 :O 2 for this process is 1: 0.85-1.0:0.1-0.2.