434132 Real Residence Time Distribution of Solids from Lagrangian Simulation in Openfoam

Wednesday, November 11, 2015: 8:30 AM
355F (Salt Palace Convention Center)
Yujian Sun and Milorad P. Dudukovic, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, Saint Louis, MO

Real residence time distribution of solids from Lagrangian simulation in OpenFOAM

Yujian Sun, Milorad P. Dudukovic*

Chemical Engineering Reaction Laboratory, Washington University in St. Louis, St. Louis, MO 63130

Abstract:

The classic tracer injection-response method to measure residence time distributions (RTD) is restricted to the close-close boundary condition which is not met by many practical processes. On the other hand, most Lagrangian codes like OpenFOAM has an "age" attribute for individual particles which records the time spent in the system by each particle. By proper statistical analysis of data, an age distribution function (ADF) of solids in the whole system may be obtained. However, such ADF differs from the real residence time distribution (RTD) of solids in the specific zones of interest, e.g. the reaction and the regeneration zones in a circulating fluidized bed reactor. To obtain the solids RTD in the pre-defined zone, another attribute called "Tres" (short for residence time) needs to be introduced for individual particles, in a way similar to how "age" is defined. However, what is different is the criterion when the time should be incremented. For Tres, it should start to increase when the position of the particle "hits" the pre-defined boundary from outside of the zone to inside, and stop to be incremented when the particle passes the boundary again leaving the zone. With Tres of statistically significant amount of particles gathered, the real solids RTD may be calculated by statistical means which can be further used in reaction engineering analysis. This work explores this potential application of Lagrangian simulation, making use of and adapting the Lagrangian codes in OpenFOAM, to obtain solids RTD in the riser and the regenerator of a circulating fluidized bed reactor.


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See more of this Session: Multiphase Reaction Engineering I
See more of this Group/Topical: Catalysis and Reaction Engineering Division