Model-based Optimization of Reactors Involved in the Steam Reforming of Bioethanol

JAVIER A. FRANCESCONI; MIGUEL C. MUSSATI; EDUARDO MIRÓ; ROBERTO O. MATO; PIO A. AGUIRRE

Rio de Janeiro (Brazil)

Congreso; ENPROMER 2005: 2nd Mercosur Congress on Chemical Engineering 4th Mercosur Congress on Process Systems Engineering; 2005

Fuel cell power systems for transportation applications have received increased attention in last years because of their potential for high fuel efficiency and lower emissions. The operation conditions of automotive vehicles require short times of start-up, compact and lightweight equipment and efficient operation at different conditions. The reformer, the water gas shift (WGS) reactor and the preferential oxidation reactor (COPROX) constitute the nucleus of the processor, and are a significant fraction of the system volume and weight. In this work we approach the synthesis and design of a system processor of ethanol using conventional reactors. A model-based reactor optimization permits to obtain both designs for reducing volumes and optimal operation conditions as temperature and pressure profiles. These results can be useful for estimating the minimum and relative sizes of the component reactors that allows this technology. The reforming process is endothermic and requires an external heat supply from hydrocarbon combustion. Then, a design for improving the heat transfer and satisfying the production levels required and the restrictions of admissible pressure drop is needed. By modeling the combustion chamber coupled to the reformer allowed optimizing the design variables to reduce the total equipment volume. The model computes the exigencies required for the constructive materials, such as maximum operation temperature for steel, refractory and insulating materials. The heterogeneous model used allows computing the optimal WGS reactor length and diameter and the optimal catalyst particle diameter. The COPROX reactor requires catalysts with high CO selectivity to reduce the oxidation of H2. According to the CO levels fed to the COPROX, a series arrangement of two reaction units with intermediate cooling is required for the case study analyzed.