Aeration chambers

Figure 5.6. Components of pneumatic conveying systems, (a) Rotary positive displacement blower for pressure or vacuum, (b) A rotary airlock feeder for fine materials (Detroit Stoker Co.), (c) A four-compartment receiver-filter (Fuller Co., Bethlehem, PA), (d) A two-stage cyclone receiver, (e) The Fuller-Kinyon pump for cement and other fine powders. Powder is fed into the aeration chamber with a screw and is fluidized with compressed air (Fuller Co., Bethlehem, PA).

Following the biological waste water purification, an easy separation of activated sludge flocks can be achieved by flotation. To facilitate this separation, the flotation cell is subdivided into two parts, each having equal superficial areas, Fig. 58. The inner cylindrical vessel serves as the aeration chamber, this being equipped with the forementioned funnel-shaped nozzle. Here, particles are brought into intimate con-... 

The method described by Grob and Zurcher (151 in which a very small amount of charcoal is used to collect volatile compounds has been modified slightly by P. S. Beevor and coworkers, Tropical Products Institute, London (1 61 to collect pheromones from insects. We have adapted and further modified this method. Briefly, it consists of a small charcoal filter prepared by sealing 3-5 mg of charcoal between two 325-mesh stainless steel frits in a 6 mm (0.D.1, 3.7 mm (I.D.l Pyrex tube (Figure 81. This filter is then placed at the exit end of an aeration chamber, and air is drawn through the aeration apparatus at a flow rate of 2.5 liters/min. When aeration is complete, the filter is rinsed with six aliquots (15-20 pi) of distilled dichloromethane the combined aliquots are concentrated to about 5-10 pi by gently warming, and isooctane or another solvent of choice for analysis by capillary GC with splitless injection is added. 

Evaluation of this system with standards (Table ll indicated that most 14- and 16-carbon aldehydes, acetates, and alcohols could be recovered with good efficiency. Recoveries vary with conditions, and thus it is necessary to calibrate an apparatus with standards under the exact conditions to be used with insects. For example, larger diameter aeration chambers reduce the efficiency of collection because of the greater surface area of glass available to adsorb the pheromone and lower wind velocities for a given flow rate. Therefore, the smallest aeration... 

During operation the fiber or fibers are placed in the aeration chamber behind the prefilter and the luer joint is attached to a vacuum pump through a flow regulator. Air is drawn through the apparatus at a rate of 1 liter/min for specified time periods. At the end of the specified time the unit is detached from the pump and inverted over a suitable receiver. The accumulated pheromone is removed from both the beads and the aeration chamber by forcing solvent through the apparatus, in the direction opposite to the air movement, from a syringe attached to the luer joint. For labeled pheromones the apparatus is washed with 3x7 ml of hexane and each wash is collected in a separate scintillation vial. 

Fig. 6.2-61 depicts two typical designs and arrangements of roller presses for pharmaceutical applications. As mentioned above, small presses in particular are sometimes equipped with rollers one-above-the-other (alternative a2). In this case, the force feeding screw is installed horizontally. It is often said that this design allows for better de-aeration as shown in Fig. 6.2-62. In this diagram, (1) is the raw blend, (2) is a special hopper equipped with a rotating flow stimulator, a separate de-aeration chamber, which is also used for feeding recycle (3) and additives (if applicable), and air removal port (4), (5) is a vacuum pad option for further direct de-aeration from the horizontal feed screw, and (6) is the recirculation of powder leakage [B.13b, B.48, B.97].

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