Gas-liquid distribution

In the range of operating temperatures and compositions, the equilibrium relations are monotonic functions of temperature of the MSA. This is typically true. For instance, normally in gas absorption Henry s coefficient monotonically decreases as the temperature of the MSA is lowered while for stripping the gas-liquid distribution coefficient monotonically increases as the temperature of the stripping agent is increased. 

The advantages of microreactors, for example, well-defined control of the gas-liquid distributions, also hold for photocatalytic conversions. Furthermore, the distance between the light source and the catalyst is small, with the catalyst immobilized on the walls of the microchannels. It was demonstrated for the photodegradation of 4-chlorophenol in a microreactor that the reaction was truly kinetically controlled, and performed with high efficiency [32]. The latter was explained by the illuminated area, which exceeds conventional reactor types by a factor of 4-400, depending on the reactor type. Even further reduction of the distance between the light source and the catalytically active site might be possible by the use of electroluminescent materials [19]. The benefits of this concept have still to be proven. 

The solvent triangle classification method of Snyder Is the most cosDBon approach to solvent characterization used by chromatographers (510,517). The solvent polarity index, P, and solvent selectivity factors, X), which characterize the relative importemce of orientation and proton donor/acceptor interactions to the total polarity, were based on Rohrscbneider s compilation of experimental gas-liquid distribution constants for a number of test solutes in 75 common, volatile solvents. Snyder chose the solutes nitromethane, ethanol and dloxane as probes for a solvent s capacity for orientation, proton acceptor and proton donor capacity, respectively. The influence of solute molecular size, solute/solvent dispersion interactions, and solute/solvent induction interactions as a result of solvent polarizability were subtracted from the experimental distribution constants first multiplying the experimental distribution constant by the solvent molar volume and thm referencing this quantity to the value calculated for a hypothetical n-alkane with a molar volume identical to the test solute. Each value was then corrected empirically to give a value of zero for the polar distribution constant of the test solutes for saturated hydrocarbon solvents. These residual, values were supposed to arise from inductive and... 

Images showing the gas-liquid distribution also give important insights into how start-up influences the resulting gas-liquid distribution. Figure 30 shows the gas-liquid distribution for a gas velocity of 66niins and a liquid velocity of... 

Examples of the use of tomographic techniques to determine gas/liquid distribution in stmctured packing is limited in the open literature. Mewes et al. [9] studied flow distribution in monoliths using capacitance tomography. A spatial... 

This equation is quite accurate in comparison with group contributing methods [40] or other predictive LSER methods [41]. For compounds where the solvatochromic parameters are known, the mean absolute error in log Dy is about 0.16. It is usually less than 0.3 if solvatochromic parameters of the solute and solvent must be estimated according to empirical rules [42], In contrast to the prediction of gas-liquid distribution coefficients, which is usually easier, the LSER method allows a robust estimation of liquid-liquid distribution coefficients. However, these equations always involve empirical terms, despite their being physico-chemically founded thermodynamic models. However, this is considered due to the fundamental character of the solvatochromic scales. 

Fig. 36. (a) The binary-gated map derived from the SD map shown in Fig. 34b. The pixels identified as being associated with local pulsing are identified as white pixels associated with constant gas-liquid distribution are identified as black, (b) The temporal autocorrelation function...

For use in modeling, the rate coefficients would also have to be corrected for gas-liquid distribution at least of propene and propane. In particular, some propene initially in the gas phase enters the liquid and is converted (making the material-balance discrepancy worse). The analyses of the liquid do not reflect this, and the calculated value of k therefore is slightly too low. Another consequence of the presence of volatiles in the gas phase is that the sum of the partial pressures of CO and H2 was a little below the 50 atm total pressure, only approaching that level more closely as propene was converted to less volatile products. 

The most crucial step in the design of monolith reactors is the proper distribution of fluids over the reactor cross section. However, the available information on the gas-liquid distribution over monoliths is limited, and additional research and development are needed in this field. It should be noted that distributing the fluid al the top of the reactor is not the end of the problem, and redistributions may be needed. This is due to the fact that the monoliths can only be manufactured in short pieces, and the desired length of the catalyst in the reactor is usually obtained by stacking monolith pieces on top of each... 

Tichy M, Borek-Dohalsky V, Matousova D, Rucki M, Feltl L, Roth Z. Prediction of acute toxicity of chemicals in mixtures Worms Tubifex tubifex and gas/liquid distribution. SAR QSAR Environ Res 2002 13 261-9. 

Saderman, A.J. Gladden, L.F. Magnetic resonance imaging as a quantitative probe of gas-liquid distribution and wetting efficiency in trickle-bed reactors. Chem. Eng. Sci. 2001, 56, 2615. 

Gas-liquid distribution. Oil and hydrogen are fed into the top of the reactor and distributed uniformly over the catalyst bed. Further, down the catalyst bed, flow maldistribution (i.e., channeling, wall flow) may take place owing to non-uniform bed properties. 

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