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MP January 5, 2003 13:51

Moving Bed
 
Hi,

I wanna know if its possible to model moving bed with gas solid reactions using Fluent...if yes,I would galdly accept any info on it..

Greg Perkins January 13, 2003 00:27

Re: Moving Bed
 
Hi,

its not directly possible with Fluent for several reasons. At this stage the multiphase models don't have heat/mass transfer and reactions and in any case, the granular model is probably a poor model for slowly moving solids flow.

I have, however developed a comprehensive set of udfs which allow all these aspects to be simulated. I'm using the udfs to study moving bed coal gasifiers and underground coal gasifiers. In this case, I have developed my own models for solids flow, heat and mass transfer and chemical reactions in the gas and gas-solid phases.

To speedup the problem, I decouple the solution of the gas and solids phases, and assume the gas phase is at a pseudo-steady-state. This allows time-steps in the order of 30+ seconds to be used for transient simulations, which is required if you want to understand the process dynamics, since solid residence times are several hours.

If you have to use small time-steps for gas-phase convergence (eg. in a fully-coupled simulation) you'll never reach an appreciable time to get the dynamics.

If you want more info,

send an email

Greg


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