Annular screen

The precession camera (Fig. 4.23), although the more complicated in its motion, produces the simplest diffraction pattern. X rays enter through the black tube at left to strike the crystal, mounted in a goniometer head. Beyond the crystal are an annular-screen holder (smaller black square) and a film holder (larger black square). The remaining machinery moves crystal, screen, and film in a precessing motion about the X-ray beam. 

Several wick stmctures are in common use. First is a fine-pore (0.14—0.25 mm (100-60 mesh) wire spacing) woven screen which is roUed into an annular stmcture consisting of one or more wraps inserted into the heat pipe bore. The mesh wick is a satisfactory compromise, in many cases, between cost and performance. Where high heat transfer in a given diameter is of paramount importance, a fine-pore screen is placed over longitudinal slots in the vessel wall. Such a composite stmcture provides low viscous drag for Hquid flow in the channels and a small pore size in the screen for maximum pumping pressure. 

Filter pack. Filter pack is the term used to describe the materials placed in the annular space between the screen and the formation (Figure 1). Aller et al. and Driscoll provide a discussion of the purpose and selection of filter pack materials. The filter pack serves a number of important mechanical functions. During well construction, it helps to keep the well screen centered in the borehole and acts to block the sealant from entering the well screen. The filter pack also improves hydraulic conductivity between the well screen and the formation, prevents formation materials from migrating to the well screen by acting as a filter, and helps support the screen and borehole. ... 

Flow to the deep shaft biological wastewater treatment plant is screened and goes through a DAF unit for fiber removal prior to entry into the deep shaft. The Ohtsu plant consists of one shaft 2.79 m (110 in.) in diameter by 100 m (330 ft) deep. The shaft design incorporates one downcomer and one riser where the downcomer is located concentrically within the shaft with the resultant annular volume serving as the riser. Mixed liquor in the shaft is maintained at approximately 5000 mg/L and the hydraulic detention time in the shaft is 1 h. Mixed liquor enters the head tank at the top of the shaft where gas disengagement occurs. The head tank is 6mxl2mx3m... 

For the central measurement, the field of view is rectangular (e.g., 0.3 by 1.25°) and for other eccentricities, the field is an annular arc similar to that provided in minimum motion photometry. The use of a CRT monitor introduces the same problem as the use of LEDs in HFP, namely, the broadband nature of the screen phosphors, and a correction must be made before reporting the peak MP optical density. A system that could employ lamps and filters instead of a CRT monitor would be difficult to design because of the complexity of the visual stimulus. 

A limited number of polyanion-polycation systems were tested using a droplet/falling annulus method (Fig. 4). This technique, which has been described elsewhere [64] reduces the net impact velocity between the droplet with the oppositely charged counterion fluid. A stream of droplets was directed into a collapsing annular liquid sheet. By matching the velocities of the droplet and sheets, the impact conditions can be moderated. It has been shown to produce monodisperse spherical capsules, though it requires several days of calibration for each new system and is obviously not practical for a massive screening such as was carried out herein. 

Fig. 11 Foamed sheet extrusion line. 1 Primary extruder, 2 blowing agent metering and flow control, 3 screen pack/breaker plate, 4 secondary extruder, 5 annular die, 6 cooling mandrel, 7 guide rolls, 8 winders. [38]...

The first slurry distributor to be tested is a simple cone 8 inches in diameter at the base and 4 feet at the top. A horizontal screen is in the annular space around the cone. 

The high resistance offered by the support screens of Zone C leads to very low flow through that zone, and also leads to a recirculating zone in the annular space between the catalyst bed and the reactor shell. The non-uniform flow through the catalyst bed also brings about significant recirculation in the central pipe. In short, the model tells us that the mere removal of shroud and filling the catalyst in Zones B and C may not lead to capacity enhancements, due to the associated problems of maldistribution. 

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