Discrete injection of oxygen enhances hydrogen production in circulating fast fluidized bed membrane reactors

The coupling of steam and oxidative reforming reactions of methane in a circulating fast fluidized bed membrane reactor (CFFBMR) has been studied. The study is based on rigorous modeling and simulation viewpoints. The concept of oxygen distribution has been investigated by employing the discrete injection approach. Feeding of oxygen through discrete injection points along the length of the reformer is compared with oxygen feeding through dense perovskite membranes (La0.4Ca0.6Fe0.8Co0.2O3-δ)(La0.4Ca0.6Fe0.8Co0.2O3-δ) and the conventional direct feeding of oxygen (co-feed). The results indicate that the discrete injection of oxygen enables to achieve in situ heat integration at low feed temperature. It is also shown that oxygen distribution along the length of the CFFBMR is beneficial in eliminating the hot spot temperature regions. The hydrogen yield shows an optimal value and is significantly affected by many key parameters such as feed temperature, pressure and number of hydrogen membrane tubes. The result also shows that the CFFBMR has a potential to develop complicated bifurcation behavior.