Catalyst-scale investigation of polydispersity effect on thermophysical properties in a commercial-scale catalytic MTO fluidized bed reactor
2023
Wan, Zhanghao | Yang, Shiliang | Hu, Jianhang | Wang, Hua
The methanol-to-olefin (MTO) process is commercialized worldwide, yet the understanding of in-furnace phenomena is still lacking. Accordingly, this work explores the multiphase flow and thermochemical characteristics in a commercial-scale MTO fluidized bed reactor using a three-dimensional multiphase particle-in-cell model. After model validations, the intrinsic relationship of solid transportation and thermochemical properties is elucidated together with the study of the polydispersity effect on reactor performance. The non-uniform gas-solid distribution in the reactor demonstrates the turbulent fluidization regime. Heat transfer coefficients (HTCs) of about 300 and 200 W/(m²·K) are observed in the medium and upper regions, respectively. The small velocity, particle Reynolds number, temperature, and HTC correspond to those large-size catalysts in the dense region where particles are nearly close packing with a large solid volume fraction. Increasing particle size distribution (PSD) width increases the catalyst HTCs and the mass fraction of C₂H₄, promoting reactor performance. Besides, increasing the PSD width enlarges gas viscosity, gas specific heat capacity, and gas thermal conductivity but decreases gas density.
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