Two dimensional fluidised bed reactor: Performance of a novel multi-vortex distributor

Abstract

The influence of the distributor configuration on interphase mass transfer, gas axial dispersion and bubble size was studied in a 2-D fluidised bed reactor for two types of distributor configurations; a novel multi-vortex (MV) distributor with tuyéres directed vertically and horizontally at different heights and a standard perforated plate distributor (baseline). The linear inlet velocity (U 0 ) ranged between 0.1 m/s and 0.35 m/s, with air as fluidising medium at ambient conditions. The ozone decomposition reaction over Fe 2 O 3 impregnated FCC catalyst was used as an indirect measure of the performance of the FBR and it was found that the MV distributor causes a significant improvement (15% average) in the conversion efficiencies at all velocities tested. Bubble size measurements (using two separate techniques) indicated larger bubbles for the MV distributor, while the visual bubbling to turbulent transition boundary (U c ) for the MV distributor was found to be lower than the baseline distributor. The interphase bubble-emulsion mass transfer was quantified using the model derived by Thompson et al. (1999) and was found to be 52% higher for the MV distributor than the baseline distributor. In addition the MV distributor exhibited near plug flow characteristics at velocities exceeding U c , while this was not the case for the baseline distributor.

Image velocimetry and statistical analysis of a mesh-coupled axial blade distributor for mass transfer in a swirling bed

“…Bed velocity in the middle of the line was noted to be larger but slowly decreased as the measurement point moved to the ends of the line, especially at lower air velocities. This decreasing trend in bed velocity is attributed to frictional forces on the bed material at both ends of the line, particularly at the outer end (Brink et al, 2011). When the particle density is high and the air velocity is below the optimum value, these frictional effects become more detrimental for the bed dynamics.…”

“…The efficiency of operation depends upon design of the air distributor. Various air distributor designs were reported in the past (Sutar and Sahoo, 2011;Paiva et al, 2009;Brink et al, 2011;Faizal et al, 2012). The most popular air distributor geometry for SFBs is the annular blade distributor.…”

Effect of Novel Swirl Distributor Plate on Hydrodynamics of Fluidized Bed Gasifier

“…The influence of a novel multi-vortex (MV) on a 2D fluidized bed's gas axial dispersion, bubble size, and mass transfer was investigated by Brink et al [12]. MV distributor resulted in 50% greater increase in mass transfer coefficient.…”

Interphase mass transfer of the high velocity bubbling fluidization regime

“…The Thompson et al [25] model was used to do a best fit of the reactor performance over the velocity range and ascertain the mass transfer and axial dispersion. As shown by both Brink et al [37] and Saayman [38], the shape of the fitted curve is dependent on the catalyst activity; therefore, if the activity changes significantly and the reactor is not fully mass transfer controlled, the method fails. Catalyst activity for sand is shown in Figure 3.…”

“…Initial work to quantify reactor performance was done using an FCC catalyst in a pseudo-2D column [37,38]. The Thompson et al [25] model was used to do a best fit of the reactor performance over the velocity range and ascertain the mass transfer and axial dispersion.…”