Holdup horizontal flow

Farooqi, S. 1. and Richardson, J. F. Trans. Inst. Chem. Eng. 60 (1982) 292-305. Horizontal flow of air and liquid (Newtonian and non-Newtonian) in a smooth pipe Part 1 Correlation for average liquid holdup. 

A method for predicting pressure drop and volume fraction for non-Newtonian fluids in annular flow has been proposed by Eisen-berg and Weinberger (AlChE J., 25, 240-245 [1979]). Das, Biswas, and Matra (Can. J. Chem. Eng., 70, 431—437 [1993]) studied holdup in both horizontal and vertical gas/liquid flow with non-Newtonian liquids. Farooqi and Richardson Trans. Inst. Chem. Engrs., 60, 292-305, 323-333 [1982]) developed correlations for holdup and pressure drop for gas/non-Newtonian liquid horizontal flow. They used a modified Lockhart-Martinelli parameter for non-Newtonian... 

The existing hydrodynamic models can be broadly classified into two different categories on the basis of empirical approach and theoretical approach. The empirical approach is based on dimensional analysis to produce explicit correlations for pressure drop and liquid holdup using flow variables and packing characteristics or using the Lockhart-Martinelli parameter, which was proposed for open horizontal The theoretical... 

The previous discussion on holdup related only to horizontal flow of gas - non-Newtonian liqmd mixtures. Very few experimental results are available for holdup in vertical upward flow with shear-thinning liqmds [Khatib and Richardson, 1984]. These authors used a y-ray attenuation method... 

Tray with slits arranged at side. Vapor or gas is guided through the horizontally flowing liquid. Thus, with a small liquid holdup a long contact time is achieved. 

For pressure drop and holdup in inclined pipe with upward or downward flow, see Beggs and Brill ]. Pet. Technol, 25, 607-617 [1973]) the mechanistic model methods referenced above may also be apphed to inchned pipes. Up to 10° from horizontal, upward pipe inclination has httle effecl on holdup (Gregory, Can. J. Chem. Eng., 53, 384-388 [1975]). 

Horizontal Blowdown Drum/Catch Tank This type of drum, shown in Fig. 26-16, combines both the vapor-liquid separation and holdup functions in one vessel. Horizontal drums are commonly used where space is plentiful, such as in petroleum refineries and petrochemical plants. The two-phase mixture usually enters at one end and the vapor exits at the other end. For two-phase streams with very high vapor flow rates, inlets may be provided at each end, with the vapor outlet at the center of the drum, thus minimizing vapor velocities at the inlet and aiding vapor-hquid separation. 

Eaton, Ben A., el al., The Prediction of Flow Patterns, Liquid Holdup and Pressure Losses Occurring During Continuous Tw o-Phase Flow in Horizontal Pipelines. /. Petrol. TechnoL, June 1967, pp. 315-328. 

Hughmark, G. A., Holdup and Heat Transfer in Horizontal Slug Gas-Liquid Flow, Chem. Eng. Sci., 20, 1964, p. 1007. 

These authors also measured the electrical conductivity of the irrigated bed in the horizontal and vertical directions. The ratio between the liquid holdup multiplied by the conductivity of the liquid and the effective conductivity of the bed was assumed to be a measure of the tortuosity of the liquid flow. 

Heywood, N. I. and Richardson, J. F. Chem. Eng. Sci. 34 (1979) 17-30. Slug flow of air-water mixtures in a horizontal pipe determination of liquid holdup by y-ray absorption. 

Chen JJJ, Spedding PL (1983) An analysis of holdup in horizontal two-phase gas-liquid flow. Int J Multiphase Flow 9 147-159... 

All solutions of Eqs. (3) such as that by Yu and Sparrow (Yl) yield the velocity profiles in each phase as a function of the interfacial position h and the pressure drop. The volumetric flow rates Qt and Q are obtained by integrating each velocity profile over the respective phase cross-sectional area. The ratio of the flow rates can then be determined as a function of only the interfacial position, and since the volumetric flow rates are known, this yields an implicit fourth order equation for the interfacial position h. The holdups Rt and Rn can be calculated once the interfacial position is known. Since each equation for the volumetric flow rates is linear with respect to the pressure drop, once the interfacial position is known the pressure drop may be easily computed. An analytical procedure for determining pressure drop and holdup for turbulent gas-laminar liquid flows has been developed by Etchells (El) and verified by comparison with experimental data in horizontal systems (A7). 

An empirical correlation of holdup was developed by Mukherjee and Brill (1983) based on over 1500 measurements of air with oil and kerosene in horizontal, inclined, and vertical flow (inclination of 90°). Their results for the holdup were correlated by an empirical equation of the form... 

A correlation for holdup by Hughmark (1962) was found to represent data quite well for both horizontal and vertical gas-liquid flow over a wide range of conditions. This was found by Duckler et al. (1964a) to be superior... 

Depending on the gas and liquid residence times required, the reactor could be operated horizontally or vertically with either downflow or upflow. Weikard (in Ullmann, Enzyklopaedie, 4th ed., vol. 3, Verlag Chemie, 1973, p. 381) discusses possible reasons for operating an upflow concurrent flow tubular reactor for the production of adipic acid nitrile (from adipic acid and ammonia). The reactor has a liquid holdup of 20 to 30 percent and a residence time of 1.0 s for gas and 3 to 5 min for liquid. 

The flow structure within circulating fluidized beds is very complex and exhibits axial as well as horizontal non uniformities as it is shown in Fig 9 Unless the solids holdup is very low and the gas velocity very high... 

In recent years attempts have been made to improve the gas-liquid mass transfer by changing the design of the mechanically agitated vessel. Mann et al. (1989) evaluated the use of horizontal baffles mounted near the gas-liquid surface. Horizontal baffles prevent vortex formation, generate less shear than standard baffles, increase gas holdup, and improve gas-liquid mass transfer. The latter two results are due to the rotational flow below the baffles, which causes gas bubbles to move upward in a spiral trajectory and induces surface aeration. For a 12-inch i.d. and 18-inch-tall stirred vessel, they showed kLat to be improved by a factor of 1.6 to 2.3 with 30 to 50% lower agitation power compared to the standard vessel. 

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