Lift tube

The conduit that feeds Rock Spring is entirely in the phreatic zone. It has been explored by SCUBA diving for roughly 400 meters. The conduit carries a flux of clastic sediments. The diver reports a lift tube where the flow rises about 4 meters up a slope. Channel facies sediments collected from bottom and top of the lift tube were dried and sieved. The resulting grain size distribution (Fig. 9) reveals little difference between the bottom and the top of the tube. These sediments are being swept down the conduit by pipe flow and quite clearly follow undulations in the pipe. 

Figure 9. Grain size disbibution in feeder conduit of Rock Spring. Diamonds bottom of lift tube squm-es top of lift tube.

The moving-bed catalytic cracking process is similar to the FCC process. The catalyst is in the form of pellets that are moved continuously to the top of the unit by conveyor or pneumatic lift tubes to a storage hopper, then flow downward by gravity through the reactor, and finally to a regenerator. The regenerator and hopper are isolated from the reactor by steam seals. The cracked product is separated into recycled gas, oil, clarified oil, distillate, naphtha, and wet gas. 

The velocity u is the mean velocity with which the coal grain flows in time r through the lifting tube ... 

In industrial practice, the length of the lifting tube is determined most frequently based on the drying rate per unit volume, which is as follows ... 

The diameter of the lifting tube is calculated from the formula... 

From Equation 51.21, the volume of the lifting tube Ep can be calculated. Knowing the lifting tube volume Ep and its diameter, we can calculate the length of the lifting tube as... 

In general, the lengths of lifting tubes do not exceed 35 m. The coal feed to the lifting tube is situated 4-6 m above the gas feed. The dryer capacity depends on the diameter of lifting tube. 

The heating medium temperature at the dryer inlet is 550°C-700°C and 70°C-170°C at the dryer outlet. The initial moisture of coal is usually 10%-15% the final moisture is about 4%-6%. A typical pneumatic dryer setup for coal drying is shown in Figure 51.8. Wet coal from the bin (11) is proportioned by feeder (12) to the lifting tube (5), where it... 

Figure 9.12 Examples of (a) perforated plate, (b) chimney, (c) bubble cap, and (d) vapor-lift tube used in TBRs (Maiti and Nigam, 2007).

These seed culture systems are similar to those described above for spat rearing. Down-wellers are PVC or plastic cylinders of different lengths equipped with bottom nylon nets to hold the mussel seed and with air-lift tubes to move the sea water through (Rg. 11.16). As mussel seed grows, the bottom nylon net can be replaced by a larger mesh size to permit a better seawater circulation through the system. 

The Houdry Catalytic Cracking (HCC) process was a precursor to FCC. Houdry catalyst particles are pellets, which are carried to a storage hopper by a conveyor belt or pneumatic lift tubes. The pellets flow down from the hopper through the reactor, and from the reactor to a regenerator. The HCC product slate is similar to that for FCC, but FCC conversions and gasoline yields are significantly higher. 

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