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Experimental and Numerical Study of Hydrodynamics in a Circulating Fluidized Bed
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kallio, Sirpa Hermanson, Alf Peltola, Juho Ritvanen, Jouni Seppälä, Maiju Srujal Shah Taivassalo, Veikko |
| Copyright Year | 2009 |
| Abstract | Fluid dynamics of circulating fluidized beds (CFB) can be computed with different methods. Typically simulations are conducted as transient to fully describe the complicated flow patterns of dense gas-solid suspensions. The computational mesh used in these simulations must be reasonably fine, which in the case of large industrial processes leads to unfeasibly long computations. To improve the modelling capabilities it is necessary to develop faster simulation methods. The most attractive approach seems to be time-averaged modelling facilitating steady-state simulation of a fluidization process. The model development and closure of the time-averaged equations requires transient simulations. A prerequisite for utilisation of the transient results is that the simulations are validated by measurements. For that purpose, a laboratory scale 2D CFB was built at Åbo Akademi University and experiments were carried out. The apparatus and the experiments are described in the present paper. The behaviour of the CFB was video recorded and the videos were analysed to determine the average voidage distribution in the CFB. The pressure distribution in the bed and the circulation rate of solids were also measured. In addition, PIV measurement methods were tested to evaluate the possibilities to analyse the velocities of individual particles and particle clusters. Two experiments done in the laboratory scale 2D CFB were simulated as transient with the Fluent software using the kinetic theory models of granular flow. The time-averaged volume fractions and velocities of gas and particles were determined for the calculation period in the studied cases. The simulation results were compared with measured flow properties, observing a reasonably good agreement. The results were further analysed with the aim to develop time-averaged CFD models. Since CFB simulations usually require a coarse mesh, additional simulations were conducted to evaluate the mesh dependence of the results with the aim to later develop closure relations that take the mesh into account. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.ffrc.fi/FlameDays_2009/3A/KallioPaper.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
