Bubbling area

Hence the point efficiency Hqq may be computed if both and in the bubbling area are known. These paiameteis are determined by the prevailing... 

In Eq. 14-96, L = m liquid downflow/(hr-m weir length) 2LudAf= fractional hole area based on ac tive ( bubbling ) area for instance, Aj =... 

The prediction of drop sizes in liquid-liquid systems is difficult. Most of the studies have used very pure fluids as two of the immiscible liquids, and in industrial practice there almost always are other chemicals that are surface-active to some degree and make the pre-dic tion of absolute drop sizes veiy difficult. In addition, techniques to measure drop sizes in experimental studies have all types of experimental and interpretation variations and difficulties so that many of the equations and correlations in the literature give contradictoiy results under similar conditions. Experimental difficulties include dispersion and coalescence effects, difficulty of measuring ac tual drop size, the effect of visual or photographic studies on where in the tank you can make these obseiwations, and the difficulty of using probes that measure bubble size or bubble area by hght or other sample transmission techniques which are veiy sensitive to the concentration of the dispersed phase and often are used in veiy dilute solutions. 

A fractional hole area (or valve slot) greater than 11% of the bubbling area. 

Va = v. a = vapor velocity through tray active bubbling area, ft/sec... 

Anti-Jump Baffles Yes / No / Vendor Preference Recessed Seal Pans YeS / No / Vendor Preference Specify Equal Bubbling Areas / Flow Path Lengths per pass Design Load ... 

Bubbling area column area minus total of downcomer and downcomer seal areas, ft or m ... 

Fractional hole area (actual hole area/bubbling area, Ab)... 

Afl = active, or bubbling, area, equal to Ac — 2Ad for single-pass plates,... 

F = ujpv, where u is the vapour rate (m/s) based on the bubbling area, and pv is vapour density (kg/m3),... 

Figure 12-9 Bubble column and spray tower reactors. Large drop or bubble areas increase reactant mass transfer,...

The total external bubble area per unit volume of bubble-free liquid (aGL) by definition is... 

For the reasons explained in the 2 previous paragraphs, most applications in fine chemicals are run in batch mode, where STR, JLR and BCR may be chosen [33] the performances of these batch hydrogenators, as shown below in 3, hinge on G/L mass transfer capability, and above all, on interfacial area a m2 of bubbles area per m3 slurry ... 

Aa Active area, same as bubbling area m2 ft2 Erriv. Em z Murphree tray efficiency, gas -/- -/-... 

Bubbling area AB (also called active area) The total tower cross-sectional area minus the sum of downcomer top area Apr, downcomer seal area ADB, and any other nonperforated areas on the tray. The bubbling area represents the area available for vapor flow just above the tray floor. 

Fractional hole area Af The ratio of hole area to bubbling area (sieve trays) or slot area to bubbling area (valve trays). 

F-factor F This is the square root of the kinetic energy of the gas, defined by Eq. (14-76). The velocity in Eq. (14-76) is usually (not always) based on the tower cross-sectional area A , the net area A, or the bubbling area AB. The user should beware of any data for which the area basis is not clearly specified. 

Fractional Hole Area Typical sieve and fixed valve tray hole areas are 8 to 12 percent of the bubbling areas. Smaller fractional hole... 

Typical open-slot areas for moving valve trays are 14 to 15 percent of tfie bubbling area. Here the higher hole areas can be afforded due to the high turndown of the valves. 

Multipass Balancing There are two balancing philosophies equal bubbling areas and equal flow path lengths. Equal bubbling areas means that all active area panels on Fig. 14-21 d are of the same area, and each panel has the same hole (or open-slot) area. In a four-pass tray, one-quarter of the gas flows through each panel. To equalize the L/G ratio on each panel, the liquid needs to be split equally to each panel. Since the center weirs are longer than the side weirs, more liquid tends to flow toward the center weir. To equalize, side weirs are often swept back (Fig. 14-22b) while center weirs often contain picket fences (Fig. 14-22c). 

The Souders and Brown constant CSB is the C-factor [Eq. (14-77)] at the entrainment flood point. Most modern entrainment flooding correlations retain the Souders and Brown equation (14-80) as the basis, but depart from the notion that CSB is a constant. Instead, they express CSb as a weak function of several variables, which differ from one correlation to another. Depending on the correlation, CSB and us,flood are based on either the net area or on the bubbling area AB. 

Work by Davies [Pet. Ref. 29(8), p. 93, and 29(9), p. 121 (1950)] based on bubble-cap tray studies suggests that the vapor pressure drop of the tray (the dry pressure drop) counteracts channeling. The higher the dry tray pres sure drop, the greater the tendency for vapor to spread uniformly over the bubbling area. If the dry tray pressure drop is too small compared with the channeling potential, channeling prevails. 

Bubbling area, AB the total tower cross-section area less the total of downcomer area, downcomer seal area, and any other nonper-forated regions (often referred to as active area, A,). In practice, onperforated regions less than 4 in wide are counted as perforated... 

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