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Emergent behavior in a low-order fluidized-bed bubble model

J.S. Halow
National Energy Technology Laboratory
Morgantown WV 26507-0880

C.S. Daw
Oak Ridge National Laboratory
Knoxville TN 37932-6472

C.E.A. Finney
University of Tennessee
Knoxville TN 37996-2210

Collective- and emergent-behavior models are becoming useful methods of simulating complex behavior arriving from the nonlinear interactions of simply behaving agents or elements. Traffic flow and the behavior of biological systems such as ant colonies are the most frequently referenced examples of collective and emergent behavior. We have explored the application of this type of model to describe the dynamics of voids in bubbling fluidized beds. The model considers the dynamics of multiple interacting bubbles in fluidized beds. Emergent collective behavior is shown to arise, consistent with observed experimental behaviors of fluidized beds. One example is the tendency in larger beds for bubbles to form a central channel. This effect is shown to occur without invoking the usual assumption that it is induced by solids circulation patterns. Other behavior predicted by this model is the tendency to form preferred paths much like the "rat-holing" observed in cohesive-powder beds and like slugging in small beds. Three-dimensional visualizations of both small- and large-scale beds will be presented to illustrate emergent behavior. Collective- and emergent-behavior models are becoming useful methods of simulating complex behavior arriving from the nonlinear interactions of simply behaving agents or elements. Traffic flow and the behavior of biological systems such as ant colonies are the most frequently referenced examples of collective and emergent behavior. We have explored the application of this type of model to describe the dynamics of voids in bubbling fluidized beds. The model considers the dynamics of multiple interacting bubbles in fluidized beds. Emergent collective behavior is shown to arise, consistent with observed experimental behaviors of fluidized beds. One example is the tendency in larger beds for bubbles to form a central channel. This effect is shown to occur without invoking the usual assumption that it is induced by solids circulation patterns. Other behavior predicted by this model is the tendency to form preferred paths much like the "rat-holing" observed in cohesive-powder beds and like slugging in small beds. Three-dimensional visualizations of both small- and large-scale beds will be presented to illustrate emergent behavior.


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Halow JS, Daw CS, Finney CEA (2000). Emergent behavior in a low-order fluidized-bed bubble model. 2000 Annual Meeting of the American Institute of Chemical Engineers (Los Angeles, California USA; 2000 November 12-17), Paper 15c.
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