The solids flow in the CFB-riser quantified by single radioactive particle tracking

✍ Scribed by Shiva Mahmoudi; Jan Baeyens; Jonathan Seville

• Book ID: 104089309
• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 936 KB
• Volume: 211
• Category: Article
• ISSN: 0032-5910
• DOI: 10.1016/j.powtec.2011.04.011

✦ Synopsis

Single radioactive particle tracking was used to measure the overall solids residence time (and its distribution) in the riser of a CFB, operating at superficial air velocities (U) of 1 to 9 ms -1 and solids circulation fluxes (G) between 20 to 600 kg m -2 s -1 . The results demonstrate that the particle motion and mixing differ according to the operating mode of the riser, with a fairly constant velocity throughout the riser achieved in the dilute or dense riser flow, but with a significant amount of back-mixing for intermediate values of U and/or G. This back-mixing is due to the coreannulus mode of particle flow. Whereas experimental results and theoretical predictions are in fair agreement for the dilute and dense riser flow, the core-annulus regime needs to account for a U and G dependent slip factor (φ), in excess of the commonly proposed value φ = 2, especially at U-U TR b 2 ms -1 . Moreover, the previously published riser operation diagram is confirmed by the experiments, although a further analysis of the core-annulus regime is needed.