Spouted beds defined

The design of the jet spouted bed requires the rigorous definition of the gas flow pattern in order for the residence time distribution to be considered. In previous papers, the regime of jet spouted bed and its hydrodynamics correlations have been defined [2-8]. The minimum jet spouting velocity is calculated by the following correlation [7]. 

Figure 2 shows examples of how the data from PEPT can be treated, in this case from a spouted bed. The simplest data output is a continuous trajectory, consisting of a large file of x, y, z, time values, plus optional continuously recorded user-defined parameters such as speed or blade position. Velocity values can be obtained from this data file, in practice by a multi-point weighted averaging technique, and time averaged velocity profiles can then be derived. It is also possible to obtain values of... 

In through circulation fixed bed dryers and in moving or suspended bed dryers (spouted beds, fluidized beds, rotary dryers, and so on), the actual interfacial area participating in heat and mass transfer is unknown. For such cases it is appropriate to define volumetric transfer coefficients for heat and mass transfer, hy and K, respectively, as follows ... 

The third parameter to be determined is the range of stable operation, and in particular the lower limit of this range that defines the gas volume flow rate which is at least necessary in order to reliably operate the spouted bed. A stable operation means the stability of particle circulation trajectories, which may be different depending on equipment construction (as noted above), but should not fluctuate too much in time. Investigations of the stable operating range have been conducted... 

Reynolds numbers - as defined by Eq. 4.8 - that correspond to the lower limit of the stable operating regimes of Fig. 4.13 may be denoted by Re n,sf Correlations developed for RCjn.st are summarized in Tab. 4.5. However, it should be noted that Fig. 4.13 and Tab. 4.5 provide only coarse estimates for the stable operation ranges of different types of spouted bed. The reason for this is that even small variations in the apparatus geometry - especially variations in the construction of the gas entrance - can have a significant influence on the fluid dynamics of the spouted... 

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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