Gas Distribution Plate

Because the gas distribution plate was an important aspect of the Union Carbide fluidization process, two U.S. patents, one issued to Montecatini of Milan, Italy, and the other to Mitsui of Tokyo, Japan, that described detailed designs of gas distribution plates at the bottom of a fluidization column that provided improved fluidization of granular solids in a fluidization column, may have proved an obstacle in order for the Union Carbide patent 

12 Reaction Zone, diameter/height ratio 1/6 to 1/7.5 seed bed required for startup 

14 Gas velocity reduction zone diameter/height ratio 1/1 to 

30 Catalyst injection point must be placed well above distribution plate 

Catalyst prepolymerization systems that were once used by some gas-phase reactors in the past, where the catalyst particle is subjected to initial polymerization conditions that promote favorable particle morphology, and then fed to the main reactor, have been eliminated from the process. 

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A groove for an O ring was machined into each half of the case, to provide a seal to prevent the gases from leaking around the edges of the gas distribution plates. 

Figure 2 is a schematic diagram of the two-section reactor body and accessories. The fluid bed section was made of self-bonded silicon carbide, 16 inches high by 6% inches o.d. with a recessed flange. The recess accommodated a 120-mesh porosity silicon carbide gas distribution plate. The nickel manifold assembly was topped by a heavy support flange. This manifold sup-... 

Granule density and strength, Proper differential pressure drop across the gas distribution plate is needed for good fluidization Fluidization, granule growth when a critical value is exceeded Granule size and its distribution, spray drying... 

The conventional top spray method shown in Figure 2 has been used for layering and coaling for decades. It evolved from the fluidized bed dryers commercialized more than 40 years ago. The substrate is placed in the product container, which is typically an unbaffled. inverted, truncated cone with a fine retention screen and an air or gas distribution plate at its base. Perforated plates such as a Conidur or Gill plate may also achieve air distribution and product retention. These types of plates may have directed holes for guiding the airflow horizontally in the product container (for side discharge as an example). Process air is drawn through the distribution plate and into the product. 

Preliminary dried silica is loaded into the section I by the loader 9 from vessel 10 on the gas-distribution plate 13 to be dried and heated up to 200°C. The air injected by the compressor 2 is used as a carrier gas. It is dried by the NaX zeolite up to a dew-point... 

Fig. 7,70 Sketches of different gas distribution plates for fluidized beds (courtesy GEA/NIRO, Sceborg, Denmark).

Fig. 7.71 is a photograph showing three of the new gas distribution plates for NIRO fluidized bed processors. 

Another multistage fluidized bed processor is depicted in Fig, 7.76. It is a rectangular apparatus in which the different chambers are separated by walls with transversely arranged connections or (as shown in Fig. 7.76) openings at the bottom, close to the gas distribution plates, both providing plug flow. Although in the sketch a common... 

B.70, pp. 15-24], The principle of this intensive, dry, fluidized bed agglomeration process is shown in Fig. 7.86. It consists of a cylindrical chamber with a perforated gas distribution plate at the bottom and operates in batch mode using cyclic fluidization and compaction of the material. 

Fig. 7.88 depicts different states of particle beds that develop above a gas distribution plate. In the first two on the left, particles are immobile. At the incipient fluidization point, the forces caused by the flowing gas and the particle mass are in equilibrium and the bed volume has reached its maximum before, at somewhat higher gas velocities, particles begin to move freely and randomly in the fluidized beds that are shown on the right. 

Fig. 7.88 Sketches depicting the different states of particle beds above a gas distribution plate.

For natural, dry agglomeration of very fine particles as described above, destructive forces, which are, for example, caused by bubbling or slugging, must be avoided. Therefore, the gas distribution plate is a finely pored diaphragm such as a sintered glass frit or a cloth which is supported by screens (see Fig. 7.85). Rewet agglomeration in fluidized beds, on the other hand, often requires the turbulent movement and wakes caused by the rising gas bubbles [B.42],... 

Due to the absence of a gas distribution plate none can get scaled or plugged. 

Between the gas-combustion chamber bottom and the reactor bed section is the high temperature grid plate. This gas-distribution plate is 1/4-inch thick, 18 inches in diameter, and made of Type 310 stainless steel. There are 584 holes in a square pattern located on 1/4-inch centers. Each hole is 0.0960 inches in diameter. 

The fuel solids are fed into the fluidized bed by means of a screw conveyor with a specially designed feeder valve. The feed port is located 5 inches above the gas distribution plate. The 2 -inch screw is constructed of carbon steel with a Type 310 stainless steel coating on the wearing surfaces. The construction details of this feeder and the auxiliary solid feed hopper system have been described by Burton and Bailie (2). The feeding unit has performed successfully in smoothly feeding 15-60 lbs of solids/hr into the fluidized bed. 

A removable perforated Cl gas distribution plate at gas entry to distribute the gases uniformly over the converter cross section. 

In FBMRs, the membranes are inserted inside the fluidized catalyst bed, serving as a product extractor or a reactant distributor. Figure 7.1 shows a typical FBMR structure for selective removal of a product (hydrogen) [4,5]. Pd-membrane tubes are placed vertically in the FBMR.The reactant gas is fed through the gas distribution plate at the bottom of the reactor to fluidize the fine particulate catalysts. Entrained solids are separated from the reaction product gas stream by internal cyclone separator and then returned to the reactor catalyst bed. 

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