Annulus separating

Diagram and photograph of a model gas turbine combustor operating on CH4/air at atmospheric pressure. Fuel is injected from an annulus separating two swirhng air streams. (From Meier, W., Duan, X.R., and Weigand, R, Combust. Flame, 144,225,2006. With permission.)... 

The solids movement in a spouted bed is initiated by the interaction between the particles and the high-velocity gas jet, so that particle flow in the spout region shapes the entire solids-flow pattern. While a mutual dependence between the solids flow in the spout and in the annulus is inherent to a spouted bed, it is nevertheless convenient to discuss the flow in the spout and in the annulus separately. 

Under these circumstances, the settling motion of the particles and the axial motion of the Hquid phase are combined to determine the settling trajectory of these particles. The trajectory of particles just reaching the bowl wall near the point of Hquid discharge defines a minimum particle size that starts from an initial radial location and is separated in the centrifuge. A radius ris chosen to divide the Hquid annulus in the bowl into two equal volumes initially containing the same number of particles. Half the particles of size i present in the suspension are separated the other half escape. This is referred to as a 50% cutoff. 

Tften, other forms of artificial lift are used to produce oil wells such as ( ivnhole submersible pumps and rod pumps that require that most of 1 formation gas be separated downhole and flowed up the annulus... 

The outer and inner tubes extend from separate stationary tube sheets. The process fluid is heated or cooled by heat transfer to/from the outer tube s outside surface. The overall heat transfer coefficient for the O.D. of the inner tube is found in the same manner as for the double-pipe exchanger. The equivalent diameter of the annulus uses the perimeter of the O.D. of the inner tube and the I.D. of the inner tube. Kem presents calculation details. 

Y=aoi,tlain = 0.02. There is a safety concern about the premixing step. One proposal is to feed A and B separately. Component A would be fed into the base of the bed using a central tube with diameter 0.212m and component B would be fed to the annulus between the central tube and the reactor wall. The two streams would mix and react only after they had entered the bed. The concentrations of the entering components would be increased by a factor of 2, but the bed-average concentrations and Us would be unchanged. Determine the fraction unreacted that would result from the proposed modification. 

Internal-loop airlift reactors (ALRs) are widely used for their self-induced circulation, improved mixing, and excellent heat transfer [1], This work reports on the design of an ALR with a novel gas-liquid separator and novel gas distributor. In this ALR, the gas was sparged into the annulus. The special designed gas-liquid separator, at the head of the reactor, can almost completely separate the gas and liquid even at high gas velocities. 

Membrane gas-separation systems have found their first applications in the recovery of organics from process vents and effluent air [5]. More than a hundred systems have been installed in the past few years. The technique itself therefore has a solid commercial background. Membranes are assembled typically in spiral-wound modules, as shown in Fig. 7.3. Sheets of membrane interlayered with spacers are wound around a perforated central pipe. The gas mixture to be processed is fed into the annulus between the module housing and the pipe, which becomes a collector for the permeate. The spacers serve to create channels for the gas flow. The membranes separate the feed side from the permeate side. 

Figure 1 shows a schematic drawing of a CAC apparatus. The apparatus consists of two concentric cylinders standing one inside the other, forming an annulus into which the stationary phase is packed. This annular bed is slowly rotating about its vertical axis. Under isocratic elution conditions the feed mixture to be separated is introduced continuously at the top of the bed at a space that remains fixed in space while the rest of the annulus is flooded with elution buffer. As time progresses, helical component bands develop from the feed point, with... 

The space between inner and outer cylinders forms the annulus. The column bottom plate is made of stainless steel and typically contains 90 exit holes below the annulus. The holes are covered by a filter plate to keep the stationary phase in place. Three different column sizes are available for the laboratory P-CAC unit the physical characteristics of the different annular columns are summarized in Table 1. The collection of the different fractions at the lower end of the annular column is regulated by a fixed glide ring system. Each chamber in the fixed glidering corresponds to an exit holes in the bottom plate of the column. The number of exit holes equals the number of chambers. The fixed glide ring system allows the continuous and controlled recovery of the separated fractions at the end of the column. Thus cross contamination is avoided and precise fraction collection is ensured. The whole process of collecting the fractions is conducted in a closed system. Unused eluent can be easily recycled. 

The geometry of the present opposed-flow burner is identical to the one designed by Puri and coworkers (see [18] for example). The burner consists of two opposing ducts with 20-millimeter diameter separated by 15 mm. The exhaust is extracted by a vacuum pump though a water-cooled annulus mounted around the bottom duct and a guard co-flow of nitrogen is issued from an annulus around the top duct. Experiments were performed with methane (99% purity) and premixed air introduced from the bottom duct and air admitted from the top duct. The flow rates were monitored using choked orifice meters. 

The device resembles a cylindrical differential mobility analyzer (DMA) in that a sample flow is introduced around the periphery of the annulus between two concentric cylinders, and charged particles migrate inward towards the inner cylinder in the presence of a radial electric field. Instead of being transmitted to an outlet flow, the sample is collected onto a Nichrome filament located on the inner cylinder. The primary benefit of this mode of size-resolved sampling, as opposed to aerodynamic separation into a vacuum, is that chemical ionization of the vapor molecules is feasible. Because there is no outlet aerosol flow, the collection efficiency is determined by desorption of the particles from the filament, chemical ionization of the vapor, separation in a mobility drift cell, and continuous measurement of the current produced when the ions impinge on a Faraday plate. 

Figure 12-21 Countercurrent moving bed and rotating annulus reactors. Chromatographic separation of spedes in a continuous chemical reactor can be accomplished with a moving bed tubular reactor or a rotating aimulus reactor that separates A, B, and C by carrying a product species counter to the flow direction because it is...

A drive mechanism raises the annulus for inserting the sample. Most samples are accommodated in a position just above the midline of the anticoincidence shield. The Ge(Li) detector is just above the sample a raise-lower mechanism provides approximately a 10-cm. vertical range in its position. The counting of small planchets does not require separation of the annuli a long plastic tongue may be used to insert the sample through a small door in the shield. 

Figure 19.14. Construction and performance of thermal diffusion columns, (a) Basic construction of a thermal diffusion cell, (b) Action in a thermogravitationai column, (c) A commercial column with 10 takeoff points at 6 in. intervals the mean dia of the annulus is 16 mm, width 0.3 mm, volume 22.5 mL (Jones and Brown, 1960). (d) Concentration gradients in the separation of cis and trans isomers of 1,2-dimethylcyclohexane (Jones and Brown, 1960). (e) Terminal compositions as a function of charge composition of mixtures of cetane and cumene time 48 hr, 50°C hot wall, 29°C cold wall (Jones and Brown, 1960).

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