Analysis of Dynamic Characteristics of Reconfigurable Modular Reactor Systems for Renewable Methanol Synthesis

A modular production system for renewable methanol synthesis is one viable way for simultaneously realizing scalable storage of renewable energy and carbon dioxide utilization. It is crucial to improve the dynamic performances of the modular reactor systems to rapidly adapt to fluctuations of renewable energy and increase the methanol yield. In this work, four configurations and their dynamic characteristics of reactors in series and parallel were investigated to elucidate the impacts of reactor configurations on the performances of reconfigurable modular reactors, in which a 2-D transient model of fixed-bed reactors for methanol synthesis was established. The dynamic characteristics of the reactor systems during startup, shutdown, disturbance, and switching were explored. The results indicated that modular reactors in series are preferred when the feed rate is less than two times the rated flow rate in a single reactor, whereas modular reactors in parallel are favorable when the feed rate exceeds six times the rated flow rate. The modular reactors in series and parallel are much more favorable for the feed rates in between. The startup and shutdown times of the reactor systems are significantly affected by the stage numbers of the reactors and the feed flow rate in a single reactor. In general, the startup and shutdown times increase with the increase of stage number and the decrease of flow rates of the reactors. The response time to flow rate fluctuations of the reactor system is mainly determined by the stage number of the reactor and the flow rate of a single reactor. Fewer stage numbers and higher flow rates lead to a rapid response. The mode switching time between different configurations is also intimately related to the flow rates. Larger flow rates result in a relatively short residence time and a rapid switching process. These results provide insights into the optimal design and operation of modular reactor systems for renewable methanol production.