Methane Steam Reforming Thermally Coupled with Fuel Combustion: Application of Chemical Looping Concept as a Novel Technology

摘要

From the environmental perspective, because of the increasing level of CO_2 in the atmosphere, different methods are presented for the separating and capturing of CO_2 from combustion. One of these new methods is chemical looping combustion (CLC). In this work, the required heat for the endothermic steam reforming process is provided by coupling the CLC as an unprecedented technique with the steam reforming process. Endothermic reactions of methane steam reforming and reduction of Fe-based oxygen carriers in a fuel reactor (FR) are coupled with exothermic reaction of oxygen-carrier oxidation in an air reactor (AR) of thermally double coupled reactors. In this novel configuration, the AR and FR operate in fast and bubbling fluidization, respectively, and steam reforming occurs in vertically fixed-bed catah/tic tubes. The results show that, by application of CLC, not only the amount of produced synthesis gas is the same as the conventional method but also the process whereby CO_2 is separated from flue gas inherently. This is the most obvious advantage of the CLC technique. Although the CO_2 separation process is very costly, it is necessary for the conventional method. In this study, temperature, mole fraction, methane and air conversion, combustion efficiency, and hydrogen yield have been investigated. Results indicate that the methane conversion and hydrogen yield obtained in this novel method are 29% and 1.04, respectively. Also, the combustion efficiency and gas conversion (O_2 and CH_4) in both of the CLC reactors (air and fuel reactors) are nearly 100%.