Packing data ceramic

Inorganic membranes (29,36) are generaUy more stable than their polymeric counterparts. Mechanical property data have not been definitive for good comparisons. IndustriaUy, tube bundle and honeycomb constmctions predominate with surface areas 20 to 200 m. Cross-flow is generaUy the preferred mode of operation. Packing densities are greater than 1000 /m. Porous ceramics, sintered metal, and metal oxides on porous carbon support... 

FIG. 14-58 Typical holdup data for random packings and the air-water system. The raschig rings are of ceramic material. To convert pounds per hour per fr to Idlograms per second per m , multiply hy 0.001.356 to convert inches to millimeters, miinltiplyhy 25.4. [Shulman etal., AIChE J. i, 247 (I.9.5.5).]... 

Figure 9-44. Gas-liquid hold-up data for ceramic rings and saddles. Used by permission of Leva, M. Tbwer Packings and Packed Tower Design, 2nd ed., U.S. Stoneware Co. (now, Norton Chemical Process Equipment Corp.) (1953).

Figure 9-83. Ammonia-air-water absorption data of Wen, with ceramic packing. Used by permission of Chin-Yung, thesis. West Virginia University (1953).

Finally, it should be mentioned that some thermal cracking on the ceramic packing material was observed at temperatures above 850°C. Whenever such an effect was detected, an attempt was made to correct for it in the coking data. A typical value for an experimental run at 810°C for 160 minutes was 35 mg coke on 5 gram of reforming catalyst, or about 0.7 percent by weight. 

Sater and Levenspiel43 studied an air-water system in a 10.16-cm-i.d. glass column packed with either 1.27-cm ceramic Berl saddles or 1.27-cm Raschig rings to a height of 3.66 m. Iodine-131 was used as liquid-phase tracer. The dynamic liquid holdup data obtained under trickle-flow conditions correlated well with the above Eq. (8-3) of Otake and Okada.38... 

The first of the widely used random packings were Raschig rings which are hollow cylinders of ceramics, plastics, or metal. They were an economical replacement for the crushed rock often used then. Because of their simplicity and their early introduction, Raschig rings have been investigated thoroughly and many data of their performance have been obtained which are still useful, for... 

Published data indicate that it is best that the continuous phase preferentially wets the packing surface, which allows the dispersed phase to travel through the column as drops. In general, a metal or ceramic packing material should be used with a continuous aque-... 

Figure 9-47. Effective interfacial areas for random ceramic tower packings. Note for gases or vapors other than air, use abscissa, G, as G/(pgas/0-075)0 . Based on the data of Fellinger [27]. Used by permission of the American Institute of Chemical Engineers AI.Ch.E. Jour., Shul-man, H. L, Ullrich, C. F., Proulx, A. Z., and Zimmerman, J. O., V. 1, No. 2, (1955) p. 253. All rights reserved.

Catalytic activity data were obtained by using a conventional fixed-bed reactor at atmospheric pressure. A stainless steel tube with an inner diameter of 12 mm was chosen as the reactor tube. Catalyst (3.5 cm, ca. 1.8 g) was placed on ceramic wall at the lower part of the reactor. The upper part of the catalyst bed was packed with 10 cm of inactive ceramic spheres (2 mm O.D.) to preheat the gas feed. The furnace temperature was controlled with a maximum variation of 2°C by an automatic temperature controller. The gas exiting the reactor was led to a condenser to remove water vapour. The remaining components were continuously analysed by non dispersive infrared (CO and CO2), flame ionisation (HC), magnetic susceptibility (O2), and chemiluminiscence (NOx). 

Figure 9.2 shows existing data for the effective thermal conductivity of packed beds. These data include both ceramic and metallic packings. More accurate results can be obtained from the semitheoretical predictions of Dixon and Cresswell (1979). Once Kr is known, the wall heat transfer coefficient can be calculated from... 

FIGURE 5.8-13 Typical vendor data ou random packing pressure drop. One-inch ceramic Raschig rings, air-water system (Norton Co.). 

If/m is the maximum packing density of the particles, which is defined as the volume fraction at which the particles touch one another, so that flow is not possible, then the actual particle volume firaction/used in injection molding is lower than/m by 5-10 vol%. This means that in a well-dispersed suspension, the particles are separated from one another by a thin layer of polymer with a thickness of about 50 nm dming the molding, so that the mixture is able to flow. Therefore, the volume fraction of particles / is determined by the particle size and distribution and the particle shape. In practice, the volume firaction of ceramic powders is determined from viscosity measurements by using a capillary rheometer. Data for the relative viscosity, i.e., the viscosity of the mixture divided by the viscosity of the unfilled polymer versus particle concentration can be well fitted by the following equation [209] ... 

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