May 22-27, 2016
As a result of highly exothermic reactions taking place in gas-phase olefin polymerization fluidized bed reactors, difficulties concerning the heat management play an important role in the optimization of these reactors. To get a better understanding of the particle temperature distribution in fluidized beds, a high speed infrared (IR) camera and a visual camera have been coupled to obtain the hydrodynamics and thermal aspects of a pseudo-2D fluidized bed (1), as shown in figure 1. The hydrodynamics are characterized by digital image analysis and particle image velocimetry (DIA/PIV) and the heat properties by IR. The experimental data is used to validate an in-house developed computational fluid dynamics and discrete element model (CFD-DEM). In order to mimic the heat effect due to the exothermic polymerization reaction in the pseudo-2D fluidized bed reactor, a model system was used. In this model system, heat is released in zeolite 13X particles (1.8~2.0 mm) due the adsorption of CO2. Characteristics of the adsorption kinetics, isotherm and reaction enthalpy have been achieved by performing Thermogravimetric Analysis (TGA) and Simultaneous Thermal Analysis (STA). By feeding gas mixtures of CO2 and N2 uniformly to the reactor, the rate of adsorption can be controlled in order to obtain a pseudo-steady state of heat production in the bed. The combined technique provides insightful information on the particle temperature distribution for different CO2 concentrations, bed aspect ratios and background superficial velocities. Furthermore, the comparison of the spatial and temporal distribution of the particle temperature distribution in fluidized beds with the simulation results of CFD-DEM provides qualitative and quantitative validation of the CFD-DEM, in particular concerning the thermal aspects.
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Zizi Li, Tom C.E. Janssen, Martin van Sint Annaland, J.A.M. Kuipers, and Niels G. Deen, "Experimental and simulation study on heat transfer in fluidized beds with heat production: An integrated DIA/PIV/IR technique and CFD-DEM" in "Fluidization XV", Jamal Chaouki, Ecole Polytechnique de Montreal, Canada Franco Berruti, Wewstern University, Canada Xiaotao Bi, UBC, Canada Ray Cocco, PSRI Inc. USA Eds, ECI Symposium Series, (2016). https://dc.engconfintl.org/fluidization_xv/70