Raschig rings properties

A column 0.6 m diameter and 4 m high is, packed with 25 mm ceramic Raschig rings and used in a gas absorption process carried out at 101.3 kN/m2 and 293 K. If the liquid and gas properties approximate to those of water and air respectively and their flowrates are 2.5 and 0.6 kg/m2s, what is the pressure drop across the column In making calculations, Carman s method should be used. By how much may the liquid flow rate be increased before the column floods ... 

Catalyst manufacturing processes usually make particles in a distribution of sizes, although special shapes such as Raschig rings or cylinders made by extrusion and other shapes made by stamping may be quite uniform. Size distribution is measured by sieving or elutriation. A mean diameter is a convenient quantity. The kind of mean value that is applicable when surface is the main property of interest is the volume-surface mean that is applied in P7.01.09. 

Carbon nitride, 27 214—215 conductivity of, 2 7 204-206 field emission properties of, 27 221 theoretical band structure calculations for, 27 203-204 Carbon nitride films, 2 7 205 Carbon nitride solids, 2 7 203 Carbonochloridic esters, 6 290 Carbon paper, 4 738-739 Carbon profile, in gas carburizing, 26 204 Carbon Raschig-ring tower packing, 22 745 Carbon reduction, of ferrovanadium, 25 518... 

Bender et al (1979) have discussed the operating characteristics of pulsed packed columns, wherein the efficiency can be improved by a factor of two through the introduction of pulsations. Raschig rings are not recommended, since the droplets of the dispersed phase are likely to adhere to the packings. Pulsed columns work well in situations where the liquid properties do not change substantially in the column. On the whole, a pulsed packed column is not a very efficient column, and it requires that the density difference between the two phases be more than 0.08 g/cm3. 

Kramers and Alberda (9) determined axial mixing properties in a fluid packed bed (water through 1-cm Raschig rings) by employing a sinusoidal input. 

TABLE (I) - CHARACTERISTICS OF THE PACKINGS AND PROPERTIES OF THE LIQUID SOLUTIONS AT 20 C G.B. glass beads - R.R. Raschig rings - S.C. spherical catalyst - G.S. glass spheres... 

Illustration 1. Acetic acid is to be extracted from water by isopropyl ether in a tower packed with carbon Raschig rings, ether dispersed. Flow rates are to be 30 cu. ft./hr. ether, 45 cu. ft./hr. water. Average physical properties are aqueous phase density pc = 63.0 Ib./cu. ft., viscosity mc = 3.1 centipoises ether phase density pD = 45.6 Ib./cu. ft. interfacial tension [Pg.308]

For many years up to the late 1960s, the use of packed columns in rectification and absorption processes was limited to relatively small plants with column diameters of up to 1 m. This was due to the properties of Raschig rings, commonly used at the time, which became less effective as the column diameter increased. It was not until Pall rings were introduced by BASF in the 1960s, that these limitations were partly reduced. In addition, little consideration was given to an even distribution of liquid at the column top and the pre-distribution of gas on inlet below the packed bed. 

Studies by WeiB et al. [11] as well as other authors [3, 25] show that calculations based on these models in relation to irrigated classic packings such as Pall or Raschig rings used for rectification systems, are only in line with experimental data, if the quotients Ap/Apo, experimentally determined using the air/water system, are multiplied with the physical property quotients > pv/pwY. with experi-... 

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