Reverse flow operation with reactor side feeding : analysis, modeling and simulation

The novel concept of reverse flow operation with reactor side feeding is studied for selective oxidation of NH3 to produce either N2, N2O, or NO. During normal reverse flow operation, where the feeds are alternately introduced from either end of the reactor, the conversion is always lower when compared to steady state, once-through operation at the same residence time. The novel concept of reverse flow operation with reactor side feeding is therefore proposed to avoid the decrease of conversion. The production rate of the desired product can be kept at a high level, which may even exceed the production of normal reverse flow operation and steady state, once-through operation. The reactor behavior was simulated for three regimes (quasi steady state, dynamic, and relaxed steady state) with varying feed positions. The development of spatiotemporal patterns inside the reactor with side feeding shows completely different behavior compared to normal reverse flow operation and steady state, once-through operation, leading to the possibility of conversion and selectivity manipulations. In addition, the proposed concept also indicates better conversion for the dynamic and relaxed steady-state regimes. The influence of shifting the feed positions to the reactor center is most pronounced if the switching time is shorter. This concept also provides an opportunity to prevent the dead gas volume in the center of the reactor if suitable feed positions can be applied. The catalyst effectiveness in this novel concept is therefore much better than during normal reverse flow operation and steady state, once-through operation, particularly in the relaxed steady-state regime.