Packing Types

Packing type Nominal size, mm Surface area, m /m Packing factor, Ep, m ... 

The movement-absorbing devices used in semirigid and nonrigid piping systems are usually called expansion joints. Based on the method by which the pressure seal is effected, joints are either of the packed type or the packless or bellows type. Selection depends not only on the required movement but also on the severity of service in terms of pressure and temperature, tolerabiUty of leakage, and the number of service cycles. 

Packed-type joints are significant for their large-movement capacities and mggedness in body constmction. When properly adapted into a piping system, their performance is satisfactory in both moderate and severe services. However, as with any packed element subject to motion, joints of this type require occasional tightening and repacking. 

Table 14-2 illustrates the observed variations in values for different packing types and sizes for the COg-NaOH system at a 25 percent reactant-conversion level for two different liquid flow rates. The lower rate of 2.7 kg/(s-m ) or 2000 lb/(h-ft ) is equivalent to 4 (U.S. gal/min)/ft and is typical of the liquid rates employed in fume scrubbers. The higher rate of 13.6 kg/(s-m ) or 10,000 lb/(h-fU) is equivalent to 20 (U.S. gal/min)/ft and is more typical of absorption towers such as are used in CO9 removal systems. For example. We note also that two different gas velocities are represented in the table, corresponding to superficial velocities of 0.59 and 1.05 m/s (1.94 and 3.44 ft/s). 

TABLE 14-2 Typical Effects of Packing Type, Size, and Liquid Rate on K o in a Chemically Reacting System, KgO, kmol/(h m )... 

The term Fp is a dimensionless dry packing factor, specific for a given packing type and size. Values of Fp are given in Table 14-7. For operating pressures above atmospheric, and for certain packing sizes, Lj and Gj a.re calculated differently ... 

Sepn. Purif., 3, 19 (1989)] takes holdup into account and applies to random as well as structured packings. It is somewhat cumbersome to use and requires three constants for each packing type and size. Such constants have been evaluated, however, For a number of commonly used packings. A more recent pressure drop and holdup model, suitable for extension to the flood point, has been pubhshed by Rocha et al. [Jnd. Eng. Chem. Research, 35, 1660 (1996)]. This model takes into account variations in surface texturing of the different brands of packing. 

The various models for predicting values of He and Hi are given in Sec. 5. The important parameters in the models include gas rate, liquid rate, gas and liquid properties (density, viscosity, siirrace tension, diffiisivity), packing type and size, and overall bed dimensions. 

Determination of pressure drop through the column (for packed columns, correlations dependent of packing type, column-operating data, and physical properties of the constituents involved are available to estimate the pressure drop through the packing for plate columns, the pressure drop per plate is obtained and multiplied by the number of plates)... 

Changing the eluent in a ready-made column is sometimes combined with a loss of packing quality. The manufacturers try to hold the number of specified solvents for one packing type as low as possible, but some eluents have to be nominated at order time. Any replacement has to be performed strictly according to the instructions of the manufacturers. Not every eluent is suitable for the long-term storage of a used column (e.g., reactive decomposition products of tetrahydrofuran or corrosion by some aqueous buffers) and have to be replaced. 

Filters of this type or class may be of the large bag filter type for large volumes of low pressure dust laden gases or vapor, or of the generally smaller cartridge or pack types for gas/vapors or liquids containing suspended solid materials. 

For equipment with rotary seals allow additional 5 Ib/hr for each conventional seal (packing type) and 2 Ib/hr for each mechanical seal and O-ring. 

The quality grading system relates to uniformity of distribution across the tower cross-section, where 100% quality indicates ideal uniform distribution. Distributors are designed to suit the system, particularly the packing type and size. 

Correct the maximum vapor velocity again for the packing type, if other than X-100 or S-100. 

Read chart. Figure 9-55, and obtain Cq, ft/sec, at packing type shown. 

A11 packing types listed are available in several different sizes. The corrugation angle is measured from the horizontal. Confirm details with manufacturer. 

Figure 9-62. Flooding data for structured packings as reported by Billet [109]. Numbers following packing type indicate specific surface area in m /m. Reproduced by pennis-sion of the American Institute of Chemical Engineers, Fair, J. R. and Bravo, J. L., Chemical Engineering Progress, V. 86, No. 1 (1990) p. 19 all rights reserved. Note, Uq = vapor velocity, meters/sec.

TOWER INTERNAL SPECIFICATIONS SPRAY OR PACKED TYPE COLUMNS... 

The moisture curing types are one-pack coatings, which, like the two-pack types have excellent chemical resistance and gloss but have a thickness limitation owing to the evolution of carbon dioxide during curing. 

Figure 3.4 (a) Tray type deaerator (b) exchange packing type deaerator (c) spray type deaerator and (d) atomizing type deaerator. 

No expensive equipment is required for OCC however, the separation efhciency depends on the analyst s experience since a new column has to be packed for each analysis. In addition, depending on the packing type (powder or slurry), stationary phase, and purpose of the separation, the separation can take from 30 min to 4 hr. The AOAC official method for the determination of carotenoids still uses OCC." Separation of carotenoids from many foods was developed on a column packed with a mixture of MgO and HyfloSupercel (or celite or diatomaceous earth) at 1 1... 

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