Static hold

Total liquid hold-up in packed bed, h[ = static hold-up, hg, plus operating hold-up, ho [64, 66]. 

The static hold-up is independent of liquid and gas rates, since it represents the liquid held in the packing after a period of drainage time, usually until constant weight of material is received. This requires approximately 1 hour for a 10-in. dia. x 36-in. packed height tower. Table 9-34 adequately summarizes the data. 

In order to use the data in systems handling liquids other than water correction equations and charts are used [66]. The charts are more convenient to use and are presented in Figures 9-46 A, B, C, D. First, determine the total or static hold-ups for water at 20°C second, determine separately the correction for viscosity, density, and surface tension third, multiply the water hold-up by each... 

Static hold-up for water, ft- /ft packing volume Water hold-up, ft liquid/ft tower volume Enthalpy of air saturated at bulk water temperature, Btu/lb dry air... 

Patel et al. [70] in a recent publication have explored the adhesive action of the mbber-siUca hybrid nanocomposites on different substrates. The rubber-silica hybrid nanocomposites are synthesized through in situ silica formation from TEOS in strong acidic pH within acryhc copolymer (EA-BA) and terpolymer (EA-BA-AA) matrices. The transparent nanocomposites have been apphed in between the aluminum (Al), wood (W), and biaxially oriented polypropylene (PP) sheets separately and have been tested for peel strength, lap shear strength, and static holding power of the adhesive joints. 

FIGURE 3.28 Static holding power test results of acrylic terpolymer-silica nanocomposite adhesives carried out on Al, W, and PP substrates. (From Patel, S., Bandyopadhyay, A., Ganguly, A., and Bhowmick, A.K., J. Adhes. Sci. TechnoL, 20, 371, 2006. Courtesy of VSP-Brill Academic Publishers.)... 

A well-substantiated correlation for air-water systems taken from the trickle bed literature (Morsi and Charpentier, 1981) was used for the volumetric mass transfer coefficients in the / , and (Rewap)i terms in the model. The hi term was taken from a correlation of Kirillov et al. (1983), while the liquid hold-up term a, in Eqs. (70), (71), (74), (77), and (79) were estimated from a hold-up model of Specchia and Baldi (1977). All of these correlations require the pressure drop per unit bed length. The correlation of Rao and Drinkenburg (1985) was employed for this purpose. Liquid static hold-up was assumed invariate and a literature value was used. Gas hold-up was obtained by difference using the bed porosity. 

Van Swaaij [52] and Charpentier et al. [53] proposed a relationship between the static liquid hold-up, I3stat, and the dimensionless Eotvos number, Eo. At high Eotvos numbers the static hold-up is inversely proportional to Eo, whereas at low Eotvos numbers, the static holdup reaches a maximum value. 

This correlation gives, for perfectly wettable solids, fairly good estimates of the static holdup for different particle-geometries and sizes. Saez and Carbonnel [26] used the hydraulic diameter, instead of the nominal particle diameter, as the characteristic length in the Eotvos number, to include the influence of the particle geometry on the static hold-up. However, no improvement could be obtained in correlating the data with this new representation. 

Wammes et al. [34], by employing three different liquids (water - ethanol and 40 % ethyleneglycol aqueous solution) with 3 mm glass spheres, obtained experimentally determined static hold-up data. Figure 5.2-24 shows the values of the static holdup as a function of the Eotvos number together with data of other authors. Wammes et al. [34] concluded that the static liquid hold-up is not affected by the total reactor pressure. 

As shown in Fig. 8.6, several typical flow patterns can be found in the monolith channels, depending on gas-liquid ratio, flow rates, viscosity, surface tension, and channel diameter. All of these flow patterns show a very low static hold-up, but only two are regular and allow stable operation the so-called Taylor-flow and the film-flow regime. 

A. Factors to be applied to water static hold-ups to determine the effect of surface tension. Used by permission of American Institute of Chemical Engineers, Al.Ch.E. Jour., Shulman, H. L, Wells, N., Ullrich, C. F., and Proulx, A. Z., V. 1, No. 2 (1955) p. 259 all rights reserved. 

At small widths, Bqi < 1, the static hold-up assumes an almost constant value. 

For purposes of comparison it is convenient to calculate the static hold-up, ox)erating hold-up and total hold-up per theoretical or practical plate. The total hold-up varies with the load, but the literature gives little definite information on this relationship. For an Oldershaw sieve-plate column with a diameter of 28 mm, containing 30 actual plates, Collins and Lantz [200] published the values shown in B. 92. The total hold-up lies between 43 and 60 ml, depending on the load, so that it can be taken to be 1.4—2.00 ml for each actual plate and 2.5—3.5 ml for each theoretical plate. According to measurements of the author s, the total hold-up of packed columns is about the same, as wHl also be. seen from Fig. 96, which indicates... 

The layout of an assembly work-place should reflect this by placing the product to be assembled in a central area within class 3 reach of both arms. The use of jigs for stable support of the product is advised. This relieves one of the operator s hand from static holding stress. 

Platinum catalyst Potential static holding conditions and potential step conditions effect on platinum dissolution and carbon corrosion Shao et al., 2008... 

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