Hydrodynamic regime, production

Appendix IOC Choice of Hydrodynamic Regime under Production Conditions. Decimicrone-Size Particle... 

To carry out this EOR operation, the entire oil field is first divided into appropriate blocks. Then, in a checkered pattern, the steam is injected successively in one block after another. To apply this method, one must study very carefully the hydrodynamic regime of the wells. To that end, every wellhead in the block must be equipped with a special device (Fig. 20). This simple attachment, designed by one of the authors, can be easily constructed in any individual machine shop. It serves to make any kind of downhole measurement while the well is in operation and without the necessity of pulling the production tubing. 

Figure 4.11. Dependence of cooling zone length Lcooi and heat emission coefficient a on hydrodynamic regime of tubular apparatus work for water (0) (heat exchange) and chlorethyl ( ) (heat exchange under proceeding of chemical reaction of liquid-phase ethylene hydrochlorination) at fixed productivity (10,34 mVh). (Tad = 374 K To = 278 K Tr = 293 K Tc = 283 K).

The periodic liquid flow changes the hydrodynamic regime and influences the external and internal catalyst wetting. Therefore the catalyst particle wetted area will be increased and decreased depending on the hquid duration. The degree of wetting will be crucially influenced. This has a strong effect on the intensity of the process, as it alters the conditions of transport of the reactants to the catalyst surface where adsorption, chemical reactions and desorption of the products take place. 

The first column shows the product mixture from a still and silent solution in which the only mixing is by convection. This is an impractical arrangement for normal use in electrosynthesis, but here it provides an interesting comparison since the major product is the isomeric mixture of diphenylmethane derivatives, similarly to the product mix at 800 kHz. Thus, insonation at 800 kHz produces less of a product switch than mechanical stirring. This is an observation which could be significant in many other multipathway electrochemical systems. Here it may be that high-frequency ultrasound induces a different hydrodynamic regime. 

The first commercial fluidized bed polyeth)4eue plant was constructed by Union Carbide in 1968. Modern units operate at 100°C and 32 MPa (300 psig). The bed is fluidized with ethylene at about 0.5 m/s and probably operates near the turbulent fluidization regime. The excellent mixing provided by the fluidized bed is necessary to prevent hot spots, since the unit is operated near the melting point of the product. A model of the reactor (Fig. 17-25) that coupes Iduetics to the hydrodynamics was given by Choi and Ray, Chem. Eng. ScL, 40, 2261, 1985. 

In summary, it can be concluded that the monolithic stirrer reactor is a convenient reactor type both for the laboratory and the production plant. It is user-friendly and can be used to compare different catalysts in the kinetically limited regime or hydrodynamic behavior in the mass transfer controlled regime. Stirrers or monolith samples can be easily exchanged and reloaded to suit the desired enzyme and/or reaction conditions. 

The fundamentals of the electrochemical response at electrodes operating in a regime of forced convection, hydrodynamic electrodes, and the information that can be obtained have been reviewed [23, 24]. Some of these electrodes are good candidates for direct introduction into flow systems, in particular tube/channel electrodes and impinging jet (wall-jet and wall-tube) electrodes. Particular practical advantages of these flow-past hydrodynamic electrodes are that there is no reagent depletion while the sample plug passes the electrodes, and there is no build-up of unwanted intermediates or products. Recent advances in instrumentation also mean... 

Gas-liquid systems are encountered very frequently in a variety of industrial applications. For example, the production of crude oil and natural gas involves the transportation of a gas and a liquid phase in pipes. Although very significant efforts have been made to arrive at a fundamental description and subsequent CFD modeling of these type of flows, unfortunately the progress is still very limited and the engineer, faced with the solution of practical problems, very often has to resort to semiempirical methods. This state of the art is mainly due to the fact that numerous flow regimes, with their specific hydrodynamic characteristics, can prevail. 

The region of floatability due to hydrodynamic pressing forces were calculated for the Stokes (Fig. 10.7) and potential (Fig. 10.8) regimes and for several values of the product of surface potentials of the bubble, and the particle v /p. As could be expected, flotation can occur even... 

It is advantageous to study modified electrodes and other complex structures at steady state, precisely because of the complexity of their dynamics. By so doing, one can eliminate time as a variable and simplify the treatment considerably. One way to achieve steady state is to assemble the structure on an electrode that can be rotated. Another is to use a UME in the steady-state regime. Hydrodynamic voltammetry at the RDE yields waves for the conversion of primary reactant to product, as shown in Figure 9.3.8. 

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