Fluidized schematic representation

Because of the inadequacies of the aforementioned models, a number of papers in the 1950s and 1960s developed alternative mathematical descriptions of fluidized beds that explicitly divided the reactor contents into two phases, a bubble phase and an emulsion or dense phase. The bubble or lean phase is presumed to be essentially free of solids so that little, if any, reaction occurs in this portion of the bed. Reaction takes place within the dense phase, where virtually all of the solid catalyst particles are found. This phase may also be referred to as a particulate phase, an interstitial phase, or an emulsion phase by various authors. Figure 12.19 is a schematic representation of two phase models of fluidized beds. Some models also define a cloud phase as the region of space surrounding the bubble that acts as a source and a sink for gas exchange with the bubble. 

Figure 23.1 Schematic representation of (incipient) particle movement brought about by upward flow of a fluid, leading to fluidization...

Figure 23.5 Schematic representation of two-region model for fluidized bed...

Figure 11.6 Schematic representation and operation of a fluidized bed reactor.

Figure 3.5. Schematic representation of the fluidized bed reactor. Px is the rate required to keep the particles in suspension. P2 is the rate of addition of fresh input solution. [From Chou and Wollast (1984), with permission.]...

Fig. 6.14. Schematic representation of a fluidized bed reactor. (Reproduced, with permission, from Ref. 1.)...

Figure 372. Schematic representations of the product handling sections of three fluidized bed coaters. (a) Top spray, (b) tangential spray (rotary fluid bed coater), (c) bottom spray (Wurster coating system)...

Figure 400. Schematic representation of the forces and movements in a rotary fluidized bed granulator " ...

A dense phase fluidized bed generally consist of a gas distributor, a cyclone, a dipleg, a heat exchanger, an expanded section, and baffles [44]. A schematic representation of a dense phase fluidized bed reactor is shown in Fig 10.3. 

Fig. 10.4. A schematic representation of a turbulent fluidized bed. The illustration shows that in a turbulent fluidized bed entrainment is significant and an internal cyclone with solids recycle through a dipleg is required. Reprinted from [82] with permission from Elsevier.

Fig. 6.3 Schematic representation of typical equipment for size enlargement by tumble/ growth agglomeration (left) and the post-treatment steps required to obtain a final product (right). Left, from the top Inclined disc (pan), drum, continuous mixer, batch mixer, fluidized bed.

Fig. 7.68 Schematic representation of three different spray dryer systems with external fluidized bed agglom-erator/dryer/ cooler (courtesy GEA/ NIRO, Soeborg, Denmark).

Fig. 7.72 Schematic representations of a circular fluidized bed with plug flow courtesy CEA/NIRO, Soeborg, Denmark).

Fig. 7.77 shows two schematic representations of a rectangular contact fluidizer which, in this case, also incorporates back-mixed as well as plug flow sections. Therefore, it can be utilized in much the same way as discussed before. Plug flow is achieved with baffles arranged transversely (see also Fig. 7.73). As shown, a rotary distributor disperses the wet feed evenly over the back-mixed section (dry feed and atomized binder liquid could be also used) which, in addition, is equipped with contact heating surfaces that are immersed in the fluidized bed (see also Fig. 7.74b). As shown in Fig. 7.77b, the heating panels can be easily removed for cleaning and maintenance. The supply of thermal energy is selected such that a substantial portion of the required heat is provided by the panels. Therefore, it is possible to reduce both the temperature and the amount of gas through the system significantly which is particularly important if the material to be treated is heat sensitive.

Some fluidized beds are used but, in general, fixed beds packed with an adsorbent are preferred for air treatments. The air flows from the bottom to the top of the reactor. A schematic representation of a VOC treatment process is given in Fig. 16. Two adsorbers are placed in parallel, one works while the other is regenerated ly steam. The desorbate is condensed in a heat exchanger and the non-soluble solvent is recovered in a settling tank. 

A typical ID two-phase model for a membrane assisted fluidized bed reactor can be used for the simulation of the fluidized bed membrane reactor for hydrogen production via methane reforming. A schematic representation of the gas flows between the compartments of the bubble and emulsion phases is depicted in Figure 10.6. The model main assumptions are ... 

Figure 10.6 A schematic representation of the two-phase fluidized bed reactor model (FBMR) (E = emulsion phase, B = bubble phase).

Figure 11.4 Schematic representation of the two fluidized membrane reactor concepts for autothermal methane reforming with integrated CO2 capture (a) Methane combustion configuration (b) Hydrogen combustion configuration, after Patil et al.

Figure 3.12 Schematic representation of a fluidized bed membrane reactor for selective removal of hydrogen. fSource After [45])...

Figure 3.7 Schematic representation of the fluidized bed membrane reactor (Gallucci et al., 2008a, 2008b).

Fig. 26. Schematic representation of CLR(s) concept. (1) Air reactor/riser, (2) Cyclone, (3) Fuel reactor, (4) fluidized bed heat exchanger/reformer, (5) Shift Reactor, (6) CO2 separation. Courtesy Chalmers University of Technology, Sweden.

Figure 6.31 shows the a schematic representation of this two-phase fluidized-bed reactor with a simple proportional control. It should be noted that the proportional control is based on the exit temperature (the average between the dense-phase and the bubble-phase temperatures), which is the measured variable, and the steam flow to the feed heater is the manipulated variable. 

Figure 4.1 Schematic representation of two novel multifunctional fluidized bed membrane reactors for the autothermal coproduction of ultrapure H2 and pure CO2 Kuipers et al., 1992 Van Sint Annaland et al., 2006). Reprinted from Gallucci et al. (2008).

Figure 25 Schematic representation of two-phase model developed for bubbling fluidized bed. (a) Two-phase model, (b) two-phase model with jetting.

Figure 2 Schematic representation of a fluid bed granulation circuit. Shown in the circuit is a fluid bed grinder-granulator. 1. Fluid bed houseing, 2. Fluidized bed, 3. Grinding roller, 4. Drive, 5. Spray head, 6. Binder solution, 7. Pump, 8. Fluidization air fan, 9. Air heater, 10. Air control valve, 11. Cyclone, 12 and 13. Rotary valves, 14. Filter bag-house. (After Denes and Ormos, 1993.)...

Figure 9 Schematic representation of the fluidized bed Couette device. 

Fig. 8. A schematical representation of the general model for particle motion in a slugging gas fluidized bed.

Figure 7.2 Schematic representation of FBMRs for hydrogen production (a) bubbling fluidization regime (b) turbulent fluidization regime (c) fast fluidization regime. U = superficial gas velocity [7 = minimum bubbling velocity U =velocity of transition from bubbling to turbulent fluidization regime U =velocity of transition from turbulent to fast fluidization regime/significant entrainment ROG = reactor off-gas V=reactor volume. Reproduced from [6]. With permission from Elsevier.

Fig. 10.5 A schematic representation of a circulating fluidized bed. The CFB loop consists of a riser, gas-soUd cyclone separators, standpipe type of downcomer, and a nonmechanical solids flow control device. Reprinted from [48] with permission from Elsevier...

The EBR technology utilizes a three-phase system, which, in the case of hydrocracking of heavy oil fractions, is composed by gas (mainly hydrogen and partially vaporized hydrocarbons), liquid (the nonvaporized heavy portion of the hydrocarbon feed), and solid (the specially designed catalyst whose physical properties lead to fluidizing within the reactor). Schematic representations of EBRs are shown in Figure 10.1. 

Figure 1. Schematic of two-phase and three-phase representations for fluidized beds operating in the bubble regime B, bubble phase C, cloud phase D, dense phase E, emulsion phase Two-phase models, a and b three-phase models, c...

Figure 4.6 Schematic of two-phase model representation of bubbling or slugging fluidized-bed reactor.

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