Flow radial

When the radial flow of fluid towards the wellbore comes under the localised influence of the well, the shape of the interface between two fluids may be altered. The following diagrams show the phenomena of coning and cuspingoi water, as water is displacing oil towards the well. 

The trend in the use of deep bed filters in water treatment is to eliminate conventional flocculators and sedimentation tanks, and to employ the filter as a flocculation reactor for direct filtration of low turbidity waters. The constraints of batch operation can be removed by using one of the available continuous filters which provide continuous backwashing of a portion of the medium. Such systems include moving bed filters, radial flow filters, or traveling backwash filters. Further development of continuous deep bed filters is likely. Besides clarification of Hquids, which is the most frequent use, deep bed filters can also be used to concentrate soflds into a much smaller volume of backwash, or even to wash the soflds by using a different Hquid for the backwash. Deep bed filtration has a much more limited use in the chemical industry than cake filtration (see Water, Industrial water treatment Water, Municipal WATERTREATiffiNT Water Water, pollution and Water, reuse). 

Retrofitting features of the more efficient reactor types have been the principal thmst of older methanol plant modernization (17). Conversion of quench converters to radial flow improves mixing and distribution, while reducing pressure drop. Installing an additional converter on the synthesis loop purge or before the final stage of the synthesis gas compressor has been proposed as a debotdenecking measure. 

The OLEFLEX process uses multiple side-by-side, radial flow, moving-bed reactors connected in series. The heat of reaction is suppHed by preheated feed and interstage heaters. The gas-phase reaction is carried out over a catalyst, platinum supported over alumina, under very near isothermal conditions. The first commercial installation of this technology, having an annual capacity of 100,000 t, was made in 1990 by the National Petrochemical Corporation in Thailand. A second unit, at 245,000 t capacity, has been built in South Korea by the ISU Chemical Company (70). 

Separability. One of the greatest advantages of a solid catalyst is that it can be separated easily from the products of reaction. To do this successfully requires careful control of the process conditions so that exposure of the catalyst to nonreactant liquids capable of affecting or dissolving either the catalytic material or the support is prevented or rninimi2ed. Solid catalysts typically are used in axial or radial flow beds and multitubular reactors. Many successful commercial processes maintain the reactants and products in the gas phase while in contact with the catalyst to avoid catalyst degradation problems. 

Catalysts intended for different appHcations may require their own unique types of reactor and operating conditions, but the key to designing a successful system is to use the same feedstock composition that is expected in the ultimate commercial installation and to impose so far as is possible the same operating conditions as will be used commercially (35). This usually means a reactor design involving a tubular or smaH-bed reactor of one type or another that can simulate either commercial multitubular reactors or commercial-size catalyst beds, including radial flow reactors. 

In most existing styrene processes, the catalyst is loaded into large, radial flow reactors, which are operated adiabaticaHy at low pressure and temperatures near 600°C. Heat is suppHed by superheated steam. During start-up, dehydrogenation begins slowly and accelerates as the Fe (HI) is reduced to Fe (II,III). The catalyst, which was red in color when fresh, turns to the characteristic black color of Fe O. ... 

FIG. 6-39 Typical stirred tank configurations, showing time-averaged flow patterns for axial flow and radial flow impellers. From Oldshue, Fluid Mixing Technology, McGraw-Hill, New Yo7 k, 1983.)... 

General Principles There are two main types of mass flowmeters (1) the so-called true mass flowmeter, which responds directly to mass flow rate, and (2) the inferential mass flowmeter, which commonly measures volume flow rate aud flmd density separately. A variety of types of true mass flowmeters have been developed, including the following (a) the Maguus-effect mass flowmeter, (b) the axial-flow, transverse-momentum mass flowmeter, (c) the radial-flow, transverse-momentum mass flowmeter, (d) the gyroscopic transverse-momentum mass flowmeter, aud (e) the thermal mass flowmeter. Type b is the basis for several commercial mass flowmeters, one version of which is briefly described here. 

Radial-flow impellers include the flat-blade disc turbine, Fig. 18-4, which is labeled an RlOO. This generates a radial flow pattern at all Reynolds numbers. Figure 18-17 is the diagram of Reynolds num-ber/power number curve, which allows one to calculate the power knowing the speed and diameter of the impeller. The impeller shown in Fig. 18-4 typically gives high shear rates and relatively low pumping capacity. 

Radial-Flow Impellers Radial-flow impellers ha e blades which are parallel to the axis of the dri e shaft. The smaller rniiltiblade ones are known as furhbics larger, slower-speed impellers, with two or four blades, are often called paclclles . The diameter of a turbine is normally... 

FIG. 18 12 Typical flow pattern for either axial- or radial-flow impellers in an unhaffled tank. 

High-Viscosity Systems A axial-flow impellers become radial flow as Reynolds numbers approach the viscous region. Blending in... 

The fluidfoil impellers (shown in Fig. 18-2) usually give more flow for a given power level than the traditional axial- or radial-flow turbines. This is also thought to be an advantage since the heat-transfer surface itself generates the turbulence to provide the film coefficient and more flow should be helpful. This is true to a limited degree in jacketed tanks (Fig. 18-34), but in helical coils (Fig. 18-35), the... 

Another type of classifier directs an air stream across a stream of the particles to be classified. An example is the radial-flow classifier Kennedy Van Saun Corp.), which Features adjustable elements to control the flow and classification. A further development on this principle is the Vari-Mesh classifier Kennedy Van Saun Corp.), which controls classification by adjustable flow baffles. A change in direction of air flow is the operating principle of the reverse-flow Superfine classifier Hosokawa Mineral Processing Systems). 

More up-to-date data of this process are employed in a study by Rase (Fixed Bed Reactor Design and Diagnostics, Butterworths, 1990, pp. 275-286). In order to keep the pressure drop low, radial flow reactors are used, two units in series with reheating between them. Simultaneous formation of benzene, toluene, and minor products is taken into account. An economic comparison is made of two different catalysts under a variety of operating conditions. Some of the computer printouts are shown there. 

An example of a typical turboexpander is shown in Fig. 29-46. Radial-flow turbines are normally single-stage and have combination impulse-reaction blades, and the rotor resembles a centrifugal-pump impeller. The gas is jetted tangentially into the outer periphery of the rotor and flows radially inward to the eye, from which the gas is jetted backward by the angle of the rotor blades so that it leaves the rotor without spin and flows axially away. 

Radial-flow turbines have been developed primarily for the production of low temperatures, but they also may be used as power-recovery devices. 

Figure 7.13 Radial flow of air to reduce suction noise...

Impeller Radial Flow. Impeller Mixed Flow. Vertical Regenerative Turbine. 

Finally, the dual-pressure eyele of Proeess 3 ean be seen sehematieally in Figure 4-9, and in its physieal eonfiguration in Figure 4-10. Note that the lineup starts with the axial flow air eompressor to the left, the radial flow nitrous gas eompressor is in the middle, and the expander in the right foreground. Figure 4-11 shows the typieal eontrol and instrument diagram for Proeess 3. 

Figure 4-10. Compressor train for dual-pressure installation consisting of an axial flow air compressor with adjustable stator blades and a radial flow nitrous gas compressor and expander. Mass flow air = 139,000 Nm /h, nitrous gases = 122,500 Nm /h Pressure air = 0.82/4.75 bar, nitrous gases = 4.38/10.8 bar Power input total = 16,840 kW Power recovery by expander = 10,950 kW.

Figure 4-12. Duty range for turbocompressors in nitric acid plants. The diagram refers to atmospheric air and gases with similar properties, such as nitrous gas (A = axial, R = radial flow compressor).

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