Fluidized catalyst beds splitting

The mean bubble size that concerns us here is on the order of 5 cm, so that the Eotvos number Eo (equal to dlgpi/a) is well over 40 for usual bubble-column liquids. The bubbles are of spherical-cap type under this condition, which is essentially equivalent to a Weber-number criterion We (equal to dy piul/a) > 20, since Ug = Vgrfb/2 (H4, H5). The bubbles in a fluidized catalyst bed satisfy the above criterion, since a- 0. Consequently, surface tension has relatively little effect, and instead the splitting is closely related to disturbances induced by the bulk turbulence, the intensity and the scale of which are mainly governed by the fluidity of the continuous phase and the operating gas velocity. 

Scientific approaches to improve bed fluidity are potentially important for fluidized bed technology. Also, further quantitative relations between bubble splitting and bed properties would be very helpful in planning and scaling-up fluidized catalyst beds. 

The reactor is the core and is generally the most researched part of the pyrolysis technology. Extensive literature is available for catalytic pyrolysis that has been carried out at both bench/laboratory scale (ie, bubbling and circulating fluidized beds, auger reactors, and conical spouted bed reactors) and analytical scale reactors (ie, analytical pyrolysis or py-GC/MS either tubular quartz micro reactor or packed bed reactor). Specific reactor designs are not discussed in this work. Catalytic fast pyrolysis can be split into two different operation modes defined by the location of the catalyst in the process in situ and ex situ (Tan et al., 2013) (Fig. 14.2). 

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