Packings pressure drop- experimental

Pressure drop experimental data for different organized packings were reported by Kiel [10]. It was found that the total pressure drop is slightly positive, for very low gas flow rates, that is, the pressure at the bottom of the column is higher than at the top. Consequently, at very low gas flow rates, pressure drop due to gas-flowing solids interaction is larger than pressure drop due to... 

Applying dimensional analysis to the experimental data for the packing pressure drop below die loading point and excluding the negligible terms, one can derive the following expression for Ag, [163] ... 

Fig. S4. Comparison of experimental data for wet packings pressure drop below and above Ibe loading point with results c cukted by Eqs. (179) (180) (sec Table 26 S>r symbols).

Pig. 22. Schematic representation of typical pressure drop as a function of superficial gas velocity, expressed in terms of G = /9q tiQ, in packed columns. O, Dry packing , low Hquid flow rate I, higher Hquid flow rate. The points do not correspond to actual experimental data, but represent examples. 

The term essentially a drag coefficient for the dust cake particles, should be a function of the median particle size and particle size distribution, the particle shape, and the packing density. Experimental data are the only reflable source for predicting cake resistance to flow. Bag filters are often selected for some desired maximum pressure drop (500—1750 Pa = 3.75-13 mm Hg) and the cleaning interval is then set to limit pressure drop to a chosen maximum value. 

Fig. 6. Examples of types of meshes developed to resolve laminar flow around particles (a) Chimera grid. Reprinted, with permission, from the Annual Review of Fluid Mechanics, Volume 31 1999 by Annual Reviews www.annualreviews.org (b) Unstructured grid with layers of prismatic cells on particle surfaces. Reprinted from Chemical Engineering Science, Vol. 56, Calis et al., CFD Modeling and Experimental Validation of Pressure Drop and Flow Profile in a Novel Structured Catalytic Reactor Packing, pp. 1713-1720, Copyright (2001), with permission from Elsevier.

This equation is based on experimental data obtained from packed towers under preluading conditions where pressure drop is low and is a linear function of gas and liquid mass flow rates Although the I,cva equation is useful for an estimation of the packed-tower pressure drop. 

Experimental studies were carried out to derive correlations for mass transfer coefficients, reaction kinetics, liquid holdup, and pressure drop for the packing MULTIPAK (35). Suitable correlations for ROMBOPAK 6M are taken from Refs. 90 and 196. The nonideal thermodynamic behavior of the investigated multicomponent system was described by the NRTL model for activity coefficients concerning nonidealities caused by the dimerisation (see Ref. 72). 

Figure 8.19 (Contin usd) The latest version of the GPDC pressure drop correlation, (rf) Superimposing experimental pressure drop data for a given pecking generates a GPDC interpolation chart for this packing.

By selecting a factor that gives the best fit of available experimental pressure drop data to the GPDC correlation curves (81b, 60). This method biases the packing factor toward the regions on the chart for which experimental data exist. 

Since packing factors are derived from experimental pressure drop data, they are affected by the inherent limitations of the experimental data (Sec. 8.2.5). 

This chapter presents an atlas of charts for interpolating flood, pressure drop, and MOC. For random and grid packings (Charts 10.1002 to 10.3517 and 10.8005 to 10.8205), the charts are plots of the Eckert generalized pressure drop correlation (GPDC) curves, with experimental data superimposed on them. These plots permit data interpolation... 

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. 

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 ... 

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... 

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