Energy-efficient design of dual circulating fluidized bed system for CCUS by multi-tube configuration with junctions

Via temperature swing adsorption, a dual circulating fluidized bed reactor can capture CO₂ through a continuous process, but controlling the temperature of the reactor at a large scale is difficult due to the non-linearity hydrodynamics and heat transfer in the scaled-up two-phase flow. In the present study, an energy-efficient design of a circulating fluidized bed reactor was investigated. A preliminary design based on numerical simulation was associated with poor heat transfer of single- and multi-tube reactors. To enhance the heat transfer performance, an innovative multi-tube reactor with junctions was proposed. The junctions improved mixing among the tubes and resolved the heat transfer imbalance between the tubes. The heat transfer coefficient of the multi-tube reactor with junctions was about 12 times larger than that of the multi-tube reactor without junctions. An experimental facility was constructed, and the reactor design was verified. Finally, thermal design analysis is performed to evaluate the design effectiveness in terms of the thermal performance of the reactor capable of continuous CO₂ capture. The results showed that the multi-tube reactor with junctions has a large thermal margin and is thus a robust and flexible design applicable to thermochemical process.