Laser diagnostic investigation of the bubble eruption patterns in the freeboard of fluidized beds: Simultaneous acetone PLIF and stereoscopic PIV measurements

Abstract

in Wiley InterScience (www.interscience.wiley.com).For the first time PIV has been applied simultaneously with acetone-PLIF in the freeboard of a fluidized bed. Here, the eruption profile of single bubbles and a continuous stream of bubbles were studied. As stereoscopic PIV was applied the out-of-plane component of the velocity was also measured. The out-of-plane component is not negligible. The observed bubble eruption patterns were in general agreement with the bubble model of Levy and Lockwood, 24 Yorquez-Ramirez and Duursma 5 and Solimene et al. 1 No qualitative difference between the eruption of a single bubble and a stream of bubbles was observed. Based on the calculated vorticity of the gas in the freeboard, it was found that the bubble induced turbulence decays fairly rapidly. VThe velocities are compared 30 mm above the surface of the bed: (--) Q ¼ 50 cc/s, (--) Q ¼ 85 cc/s.

Magnetic resonance imaging of gas dynamics in the freeboard of fixed beds and bubbling fluidized beds

“…Firstly, it is possible that the flow pattern seen here is influenced by the walls of the column, as the column is only 52 mm in diameter. However, similar findings have been reported in larger beds using laser-based techniques (Duursma et al, 2001;Hartung et al, 2008;Müller et al, 2009;Solimene et al, 2007;Yórquez-Ramıŕez and Duursma, 2001). Secondly, the measurements reported here are a time-averaged measurement.…”

“…This toroidal vortex then rises steadily up the freeboard with the bulk flow of the gas. This theory was confirmed by measurements at a variety of points in the freeboard, as well as later measurements using planar laser induced fluorescence (PLIF) (Hartung et al, 2008;Müller et al, 2009;Solimene et al, 2007) and particle image velocimetry (PIV) (Duursma et al, 2001; Yórquez-Ramıŕez and ).…”

Properties of stationary (bubbling) fluidised beds relevant to combustion and gasification systems

“…This pocket of gas is released at the centre of the dome. Hartung et al (2008) and Müller et al (2008a) undertook simultaneous acetone-PLIF (planar, laser-induced fluorescence) and particle image velocimetry (2-D PIV and stereoscopic PIV) to study how bubbles of gas containing acetone vapour were ejected from the surface of a square bed (200 mm ¥ 200 mm cross section) of Group B particles maintained at minimum fluidisation. The subsequent fate of the acetone as it mixed with the main fluidising air was also recorded.…”

Comparison of bubble eruption models with two-fluid simulations in a 2D gas-fluidized bed

“…Despite the fact that gas velocities have been measured in the freeboard close to erupting bubbles, e.g. [26][27][28], the existing experimental techniques do not allow a direct measurement of the gas velocity through the particles in the bubble dome. The lack of experimental measurements of the simultaneous particle and gas velocities in a two-dimensional erupting bubble means that, at present, such coupled information is only available from numerical "experiments".…”