Packing pressure drop and

Venturi scmbbers can be operated at 2.5 kPa (19 mm Hg) to coUect many particles coarser than 1 p.m efficiently. Smaller particles often require a pressure drop of 7.5—10 kPa (56—75 mm Hg). When most of the particulates are smaller than 0.5 p.m and are hydrophobic, venturis have been operated at pressure drops from 25 to 32.5 kPa (187—244 mm Hg). Water injection rate is typicaUy 0.67—1.4 m of Hquid per 1000 m of gas, although rates as high as 2.7 are used. Increasing water rates improves coUection efficiency. Many venturis contain louvers to vary throat cross section and pressure drop with changes in system gas flow. Venturi scmbbers can be made in various shapes with reasonably similar characteristics. Any device that causes contact of Hquid and gas at high velocity and pressure drop across an accelerating orifice wiU act much like a venturi scmbber. A flooded-disk scmbber in which the annular orifice created by the disc is equivalent to a venturi throat has been described (296). An irrigated packed fiber bed with performance similar to a... 

Fig. 24. Generalized method using log scales for estimating packed column flooding and pressure drop, AP, in kPa/m g = gravitational constant, 9.81 m/s t = kinematic viscosity in mm /s (= cSt) E, G have units of kg/(m s) are in kg/m and the packing factor, F, in can be found in...

Porous Media Packed beds of granular solids are one type of the general class referred to as porous media, which include geological formations such as petroleum reservoirs and aquifers, manufactured materials such as sintered metals and porous catalysts, burning coal or char particles, and textile fabrics, to name a few. Pressure drop for incompressible flow across a porous medium has the same quahtative behavior as that given by Leva s correlation in the preceding. At low Reynolds numbers, viscous forces dominate and pressure drop is proportional to fluid viscosity and superficial velocity, and at high Reynolds numbers, pressure drop is proportional to fluid density and to the square of superficial velocity. 

Temperature-sensitive mixtures are to be separated. To avoid decomposition and/or polymerization, vacuum operation may then be necessary. The smaller liqmd holdup and pressure drop theoretical stage of a packed column may be particularly desirable. 

Example 13 Packed Column Pressure Drop Air and water are flowing coiinterciirrently through a bed of 2-inch metal Pali rings. The air mass velocity is 2.03 kg/s-m (1500 Ihs/hr-fd), and the liquid mass velocity is 12.20 kg/s-m (9000 Ihs/hr-fr). Calculate the pressure drop hy the generalized pres-... 

Efficiency and pressure drop data for Siilzer BX metal gauze structured packing and for three test mixtures are shown in Fig. 14-7.5. For the ethyl benzene/styrene test mixture, the effect of operating pressure is shown. The high viscosity mixture, propylene glycoL/ethylene... 

Once packing heights are determined in other sections from HETP (distillation) or Koa (absorption), the height allowances for the internals (from Figure 1) can be added to determine the overall column height. Column diameter is determined in sections on capacity and pressure drop for the selected packing (random dumped or structured). 

Usually used stacked, and as first layers on support grids for smaller packing above. Pressure drop relatively low, channeling reduced for comparative stacked packings. No side wall thrust. 

We opened the Packed Columns subsection with the statement by Lieberman that, based on his design and operating experience, a properly designed packed tower can have 20 0% more capacity than a trayed tower with equal number of fractionation stages. Kister states that packing s pressure drop is typically three to five times lower than that of trays. 

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,... 

Figure 9-19. Comparison of typical valve tray and random packing showing that packing reduces pressure drop significantiy. Used by permission of Kunesh, J. G., Chemical Engineering, V. 94, No. 18 (1967) p. 101, ail rights reserved.

These ratios are useful in dealing with small towers, and serve as guides for the borderline cases of others. There are no guides to the smallest sized packing to place in a tower. However, /4-in. is about the smallest ceramic used with %-in. and 1-in. being the most popular. Operating and pressure drop factors will usually control this selection. 

Figure 9-21D. Loading, flooding and pressure drop coireiation (one of earlier versions). Adapted by permission from Leva, M. Tower Packing and Packed Tower Design, 2nd ed. U.S. Stoneware Co.

As packing factor, F, becomes larger by selection of smaller sized packing gas capacity for the column is reduced and pressure drop will increase for a fixed gas flow. 

Norton offers a new high performance system centered around an improved Intalox metal tower packing, including effective internals to provide the distribution and pressure drop consistent with the higher performance of the packing itself. 

Figure 9-50. HETP and pressure drop data for a typical distillation system. Packing equivalent to X-200 (8 strands), stainless steel. System methylcyclohexane and toluene. Reflux Ratio 100%. Column Diameter 18 inches. Packed Height 5 feet. Used by permission ACS Industries, Inc., Separation Technology Division, Bull. B-129 (1992).

Lowe, H. J. and Christie, D. G. Inst. Mech. Eng. Symposium on Heat Transfer (1962). Paper 113, 933. Heat transfer and pressure drop data on cooling tower packings, and model studies of the resistance of natural-draught towers to airflow. 

Consider the gas-phase decomposition A B -b C in an isothermal tubular reactor. The tube i.d. is 1 in. There is no packing. The pressure drop is 1 psi with the outlet at atmospheric pressure. The gas flow rate is O.OSSCF/s. The molecular weights of B and C are 48 and 52, respectively. The entering gas contains 50% A and 50% inerts by volume. The operating temperature is 700°C. The cracking reaction is first order with a rate constant of 0.93 s . How long is the tube and what... 

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