(24g) Three-Dimensional CFD Simulation of a Circulating Fluidized Bed Reactor for CO2 Capture Processes Using Solid Sorbents

Circulating fluidized beds (CFB) have been widely used in the fluid catalytic cracking (FCC) units, gasification of coal and biomass, synthesis of Olefins from Methanol, and chemical looping and will continue to be used in forthcoming processes such as CO₂ capture units using solid sorbents. The simulation of individual parts of the system was recently performed and can provide qualitative, but not quantitative, estimation of the system behavior. However, to quantitatively simulate the entire loop, CFD simulation of the full-loop of the circulating fluidized bed (NETLâ??s C2U unit) was performed. For this system, our calculations showed that the circulating fluidized bed behavior through the transient period, and reaching to a statistical steady state after about 10 seconds. This time strongly depends on the initial condition of the simulations; however, the order of magnitude of this time depends mainly on the geometry and scale of the system and should be in vicinity of 10 seconds for different initial conditions that was also reported by NETL for the bench-scale C2U unit. The calculated fluidization regime, pressure drop, and solid circulating rate using our simulation were in agreement with NETL experimental observation. The results of our simulation showed the excellent capability of our model in describing the flow behavior in a circulating fluidized bed system which includes the whole range of solid volume fraction from very dilute parts (i.e., riser) to very dense parts (i.e., standpipe).