Radial inlet

Fig. 35. Precompressed cylinder head with radial inlet and outiet valves (174).

As an example, consider a situation for an open tube with purely radial inlet flow. The boundary conditions that describe this situation are, at the inlet boundary r = 1,... 

Fig. 6.22 Nondimensional streamlines and velocity profiles for an isothermal tubular flow with purely radial inlet velocity. The streamlines shown are for a Reynolds number of 1. The nondimensional velocity profiles are shown for Reynolds numbers of 1, 10, and 100.

Another routing scheme presented in Fig. 10 is primarily based on the Coriolis force/c (Eq. 4). In an inverse Y-channel geometry, the common radial inlet splits into two symmetric outlets. As the Coriolis force/c prevails the centrifugal force... 

From these calculations, it could be concluded that the turbulence in the end-section is not as high as expected and that therefore this expensive part of the homogenizer cannot be a dominant factor in the good performance. The hig st turbulence fluctuations occur at the periphery of the fi(ee liquid jet coming out of the inlet nozzle for the continuous phase. A few millimeters behind this nozzle is a second nozzle and between these two nozzles the radial inlet for the dispersed phase is located. It can be seen that the second nozzle is too small and also that the distance between these two nozzles is too small. The fi ee liquid jet coming out of the first nozzle is broken at the second nozzle, so the pressure in the inlet for the dispersed phase is not low enough to suck in a sufficient amount of the dispersed phase. 

The adjustment of the bc s to the experimental situation is somewhat problematic. Due to the particular way how the gas is fed into and taken out of the reactor the flow condition within inlet and exit cross-sections are rather undefined. QJithin a zone of at least 1 cm width at both sides of the reaction section there are radial and axial flow components. More details on the conversion of radial inlet flow to axial flow in packed beds can be found in a paper by Szekely and Poveromo (10). 

Inlet guide vane Gas enters the unit through the radial inlet channe]. Inlet guide vane is used to properly distribute the gas evenly to the first stage impcUer. It may be fixed or adjustable. 

The simplest type of centrifugal device is the cyclone separator (Fig. 3.4), which consists of a vertical cylinder with a conical bottom. The centrifugal force is generated by the fluid motion. The mixture enters in a tangential inlet near the top, and the rotating motion so created develops centrifugal force which throws the particles radially toward the wall. 

Fig. 19. Comparison of the predictions of k-e model and experimental data for a confined swirling flow, (a) Flow configuration where 4. is the primary inlet, D = 25 mm, and B is the secondary inlet, = 31 mm, = 59 mm and the step height, H = 31.5 mm. (b) Predicted and measured streamline values where r/H is the ratio of the radial distance from the centerline to the step height.

Air is compressed to modest pressures, typically 100 to 200 kPa ( 15-30 psig) with either a centrifugal or radial compressor, and mixed with superheated vaporized butane. Static mixers are normally employed to ensure good mixing. Butane concentrations are often limited to less than 1.7 mol 1 to stay below the lower flammable limit of butane (144). Operation of the reactor at butane concentrations below the flammable limit does not eliminate the requirement for combustion venting, and consequendy most processes use mpture disks on both the inlet and exit reactor heads. A dow diagram of the Huntsman fixed-bed maleic anhydride process is shown in Figure 1. 

Radial density gradients in FCC and other large-diameter pneumatic transfer risers reflect gas—soHd maldistributions and reduce product yields. Cold-flow units are used to measure the transverse catalyst profiles as functions of gas velocity, catalyst flux, and inlet design. Impacts of measured flow distributions have been evaluated using a simple four lump kinetic model and assuming dispersed catalyst clusters where all the reactions are assumed to occur coupled with a continuous gas phase. A 3 wt % conversion advantage is determined for injection feed around the riser circumference as compared with an axial injection design (28). 

Figure 2-11 illustrates the potential severity of three problems that tend to eorrelate turboexpander inlet pressure thrust bearings, erosion of rotor and nozzles, and radial bearings. 

The reaetion turbine avoids this U-turn and its effieieney penalty. In the reaetion turbine half of the pressure energy is spent aeross the rotor, so there must be a seal around the rotor. With the rotor inlet at its periphery, the diseharge from the rotor may now be ehosen at a redueed diameter radial, or quasi axial, shaft-eoneentrie position. Sinee the diseharge is obviously smaller in diameter, the rotor seal will also be smaller in diameter beeause it only needs to suiTound the diseharge portion of the rotor. As a eonsequenee, seal loss is redueed and shaft thrust deereases as well. Likewise, the diseharge or seeondary nozzle losses are redueed beeause the gas exits at lower veloeity. 

To reeap, a turboexpander is a radial inflow turbine. The expansion proeess is aeeomplished in two steps primary and seeondary expansion. Primary expansion oeeurs in the inlet guide vanes and seeondary expansion oeeurs in the radial wheel. The proeess is isentropie and thermally effieient with reeoverable eold energy. Turboexpanders used in dew point eontrol require the following ... 

In the case of nitrous acid plants, application of integrally geared process gas radial turbines and compressors are used in plants with capacities ranging from 120-600 t/day and higher. For air compression, up to three compressor stages are connected in series. To increase efficiency, the inlet temperature of the individual stages is reduced by using two external intermediate coolers. 

Figure 4-40. Two-stage radial inflow expander with variable inlet guide vanes (right). (Source Demag Delaval.)...

With a lower temperature, the turbine is best used by allowing the baek-pressure to fall and thus obtain more power. In radial inflow turbines, the relative veloeity at the turbine inlet is small. Any ehanges are, therefore, far less signifieant than with high relative veloeity impulse wheels. Commonly, a turboexpander tolerates as mueh as a 30% ehange from its designed enthalpy. The effeet on effieieney was shown earlier in Figure 3-12. 

A new nose eone was obtained and initial maehining performed by die repair faeility. The nose eone is supported by six radial pins. The nose eone and inlet easing were sent to die main plant to ensure die pin hole loeations were properly positioned. Here, die inlet easing was assembled and oversized pin holes were drilled and reamed in die pieees. Pins made to fit die holes were also maehined. Repau maehining... 

On the expander side, the expander wheel is surrounded by the nozzle vanes. The nozzle vanes, in turn, reeeive gas from a toroidal spaee that is eonneeted to tlie expander inlet piping. Any non-uniformity in the torus spaee and/or in the nozzle vane design may result in a non-uniform pressure distribution around the expander wheel. Non-uniform gas pressure around the expander wheel will result in a non-uniform load and, henee, produee a gas dynamie radial load on the bearing. In the expander ease, however, the nozzle throat flow resistanee is mueh larger than the easing peripheral pressure nonuniformity. The latter aets as a buffer making the expander wheel eireumferential pressure variations smaller than those of the eompressor side. This smaller pressure variation produees mueh less radial load when eompared to that of the eompressor side. 

H = work per lb of fluid U2 = impeller peripheral veloeity Ux = indueer veloeity at the mean radial station Vff2 = absolute tangential fluid veloeity at impeller exit Vgx = absolute tangential air veloeity at indueer inlet... 

Supposing constant rotational speeds, no slip, and an axial inlet, the velocity triangles are as shown in Figure 6-10. For the radial vane, the absolute tangential fluid velocity at the impeller exit is constant—even if the flow rate is increased or decreased. 

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