Pressure drop in packing

Material balances, often an energy balance, and occasionally a momentum balance are needed to describe an adsorption process. These are written in various forms depending on the specific application and desire for simplicity or rigor. Reasonably general material balances for various processes are given below. An energy balance is developed for a fixea bed for gas-phase application and simphfied for liquid-phase application. Momentum balances for pressure drop in packed beds are given in Sec. 6. 

The allowable pressure drop influences the choice of the particle size and helps determine the column length. Equations for estimating the pressure drop in packed beds are given in Section 6. 

Chilton, T. H. and A. P. Colburn, Heat Transfer and Pressure Drop in Empty Baffled and Packed Tubes, Part II, Pressure Drop in Packed Tubes, Trans. Am. Inst. Chem. Engrs. 26, 178, 1931,... 

A new generalised correlation for pressure drop in packed columns, similar to Figure 11.44, has been published by Leva (1992), (1995). The new correlations gives a better prediction for systems where the density of the irrigating fluid is appreciably greater than that of water. It can also be used to predict the pressure drop over dry packing. 

Gayler, R. and Pratt, H. R. C. Trans. Inst. Chem. Eng. 29 (1951) 110. Symposium on liquid-liquid extraction. Part II. Hold-up and pressure drop in packed columns. 

Figure 1337. Corn-elation of flow rates, typical pressure drop behavior, and packing factors of random packed beds. [Eckert, Foote, and Walter, Chem. Eng. Prog. 62(1), 59 (1966) Eckert, Chem. Eng. 14 Apr. 1975)]. (a) Correlation of flow rate and pressure drop in packed towers, (b) Typical pressure drop data 2 in. porcelain intalox saddles, with F = 40, in a bed 30 in. dia by 10 ft high, (c) Packing factors, F, of wet random packings-...

Although several attempts have been made to correlate data of pressure drop in packed beds in accordance with the general theory of granular beds, no useful generalization has been achieved. In any event, all manufacturers make available such data measured for their packings, usually only for the air-water system. Samples of such data are in Figures 13.37, 13.38, and 13.40. 

Heat transfer and pressure drop in empty, baffled, and packed tubes. II. Pressure drop in packed tubes. Ind. Eng. Chem., 23 913-919. Christiansen, J. E. 

The primary factors that affect pressure drop in packed towers are (1) fluid-flow rates, (2) density and viscosity of the fluids, and (3) size, shape, orientation, and surface of the packing particles. Figure 16-17 illustrates the effects of fluid rates at constant operating pressure, and Fig. 16-19 shows how increased gas velocity due to reduction in operating pressure can affect the pressure drop. 

Pressure drop in packed distillation tower as fimction of gas rate and operating pressure. 

Many methods have been proposed for estimating pressure drop in packed towers. Most of these methods are based primarily on experimental data obtained with countercurrent flow of water and air through various types of packed towers. Because of the empirical nature of these correlations and the fact that the effects of some of the variables are not included, it is always best to predict pressure drops in the design of packed towers on the basis of experimental data obtained with equipment operating under conditions equivalent to those involved in the design. If such data are not available, approximations can be made by using the methods outlined in the following discussion. 

Constants for estimating pressure drop in packed towers by Eq. (22)... 

Levaf has correlated experimental data to obtain the following empirical equation for estimating pressure drop in packed beds under preloading conditions with simultaneous counterflow of liquid and gas ... 

Example 6 Estimation of pressure drop in packed tower. A column 2 ft in... 

The review published by Ergun (E2) provides a definitive description of pressure drop in packed tubes when the ratio of particle diameter to tube diameter is sufficiently low. In addition, although the complicated relationship between the diameter ratio, the fraction void and the friction factor can not be accurately represented without some explicit dependence of the friction factor on the diameter ratio, Ergun showed that his correlation does work for a wide variety of experimental conditions. The friction factor is calculated from the expression... 

The differential form of the design equation [i.e,. Equation (2-17)] must be u d when analyzing reactors that have a pressure drop along the length of the reactor. We discuss pressure drop in packed-bed reactors in Chapter 4. Integrating with the limits W = 0 at 2( = 0 gives... 

This chapter focuses attention on reactors that are operated isotherraally. We begin by studying a liquid-phase batch reactor to determine the specific reaction rate constant needed for the design of a CSTR. After iilustrating the design of a CSTR from batch reaction rate data, we carry out the design of a tubular reactor for a gas-phase pyrolysis reaction. This is followed by a discussion of pressure drop in packed-bed reactors, equilibrium conversion, and finally, the principles of unsteady operation and semibatch reactors. 

Differential form of Ergun equation for the pressure drop in packed beds... 

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