Conical diffuser

Vaned diffuser ioss. Vaned diffuser losses are based on conical diffuser test results. They are a function of the impeller blade loading and the vaneless space radius ratio. They also take into account the blade incidence angle and skin friction from the vanes. 

For a given area of diffuser opening Aq, the entrainment ratio is proportional to the distance jc (for compact, radial, and conical diffuser jets)... 

Gases are preheated, mixed, and fed downwards to the bed by a conical diffuser and baffle to assist uniform flow across the whole bed. Despite these precautions, localized hot spots form on the gauzes. Such hot spots vary in intensity and position and this phenomenon is termed flickering . 

Figure 3.16. Design of gas entrance region for gas distribution (a) conical diffuser and (b) streamline injector and a distributor...

I FIGURE 7.19 Types of diffuser jets (o) compact (b) linear (c) radial (d) incomplete radial (e) conical. ... 

According to Shepelev, the theoretical values of the Ki/ratio for air supply through nozzles with uniform velocity distribution at the outlet cross-section is 0.9 for compact jets and 0.95 for radial, conical, and linear jets. Practically, for different types of air diffusers, this ratio can vary from 0.7 to 3.0. 

Procedure. Pipette 25 mL of the standard OAM sodium chloride into a 250 mL conical flask. Add 10 drops of either fluorescein or dichlorofluorescein indicator, and titrate with the silver nitrate solution in a diffuse light, while rotating the flask constantly. As the end point is approached, the silver chloride coagulates appreciably, and the local development of a pink colour upon the addition of a drop of the silver nitrate solution becomes more and more pronounced. Continue the addition of the silver nitrate solution until the precipitate suddenly assumes a pronounced pink or red colour. Repeat the titration with two other 25 mL portions of the chloride solution. Individual titrations should agree within 0.1 mL. 

Before any chemistry can take place the radical centers of the propagating species must conic into appropriate proximity and it is now generally accepted that the self-reaction of propagating radicals- is a diffusion-controlled process. For this reason there is no single rate constant for termination in radical polymerization. The average rate constant usually quoted is a composite term that depends on the nature of the medium and the chain lengths of the two propagating species. Diffusion mechanisms and other factors that affect the absolute rate constants for termination are discussed in Section 5.2.1.4. 

Velocity seals are more recent developments in air seal design. They use conical baffles to redirect and focus the purge gas flow field just below the flare tip to sweep air from the flare stack. Some velocity seal designs can reduce the purge gas flow rate requirement to about 1/10 of the rate needed without the seal. Also, some velocity seal designs reportedly require only about 25 to 33 percent of the purge gas used in diffusion seals (AICliE-CCPS, 1998). More details about air (purge reduction) seals may be found in API RP 521 (2007). 

The flow of oxygen through the inner capillary of the burner (Fig. 1 b) is laminar. The estimated Reynolds number in this region for 1000 bar (Fig. 4) is about 200, much below the critical number for turbulence. This is also true for the other pressures investigated. The flames can clearly be considered as diffusion flames. Because of their conical shape the conventional simplified treatment of laminar diffusion flames can be applied [16 — 18]. According to Burke and... 

In a 20-mL conical flask, [NCBujJa [M(CN)g] (100 mg for Mo, 107 mg for W, 0.096 mmol) is dissolved in methanol (6 mL). A solution of [Ni(H20)6][(N03]2 (42 mg, 0.144 mmol) in methanol (4 mL) is then added at room temperature with stirring, which immediately gives a yellow solution. Slow diffusion of diethyl ether into this solution as described above gives pale yellow crystals (where M = Mo) and yellow-brown crystals for the W analog. The crystals are isolated as described above and any precipitate is removed by washing with a mixture of diethyl ether/methanol (2 1). The crystals are stored cold in this solvent mixture. 

The process to prepare the blend was relatively straightforward. Active A was milled through a 0.075"-opening conical miU. All the other components were screened through a 20 mesh (840-nucron) screen. AU materials except the lubricant were blended in a diffusion blender. The lubricant was blended for a short time at the end. 

Cylinders, Ellipsoids, and Elliptical Paraboloids. The diffusion-limited growth of particles whose planar intercepts are conic sections can also be analyzed by the scaling method. For example, the scaling function appropriate for a cylinder is T] = r/y/t.4 The solution for the growth of a cylinder is obtained in Exercise 20.5. 

As described in the introduction, submicrometer disk electrodes are extremely useful to probe local chemical events at the surface of a variety of substrates. However, when an electrode is placed close to a surface, the diffusion layer may extend from the microelectrode to the surface. Under these conditions, the equations developed for semi-infinite linear diffusion are no longer appropriate because the boundary conditions are no longer correct [97]. If the substrate is an insulator, the measured current will be lower than under conditions of semi-infinite linear diffusion, because the microelectrode and substrate both block free diffusion to the electrode. This phenomena is referred to as shielding. On the other hand, if the substrate is a conductor, the current will be enhanced if the couple examined is chemically stable. For example, a species that is reduced at the microelectrode can be oxidized at the conductor and then return to the microelectrode, a process referred to as feedback. This will occur even if the conductor is not electrically connected to a potentiostat, because the potential of the conductor will be the same as that of the solution. Both shielding and feedback are sensitive to the diameter of the insulating material surrounding the microelectrode surface, because this will affect the size and shape of the diffusion layer. When these concepts are taken into account, the use of scanning electrochemical microscopy can provide quantitative results. For example, with the use of a 30-nm conical electrode, diffusion coefficients have been measured inside a polymer film that is itself only 200 nm thick [98]. 

HYPOL-immobilized A.azollae. After an initial decrease of cell contents, the foam pieces became densely populated with cells. It was found that the constant shaking of the conical flasks in which the cells and foams were incubated causes loss of cells at all exposed surfaces of the foam pieces, as they constantly mb against each other. A lower shaking frequency increased cell density on the foam pieces, but cannot be too low because of diffusion problems that then arise. This same effect was found with immobilisation on preformed polyvinyl (PR 22/60) foam. 

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