Plate spacing Plates

Turn-down Plate material Downcomer Plate spacing Plate thickness Plate pressure drop... 

Air volumetric flow= 100,000 adfn Uniform flow distribution through 10 ducts Duct height = 30 ft with 12 in. plate-to-plate spacing Plate length = 36 ft Inlet loading = 14 gr/ft ... 

Since the behavior of packed columns [2,3,4, 5] and bubble cap columns [6] has been previously reported, this research at the National Bureau of Standards was primarily concerned with the characteristics of perforated or sieve plate columns. Such parameters as plate spacing, plate geometry, maximum allowable vapor velocity, weir height and downcomer area were investigated, and the results of these investigations were applied to the design of a pilot plant column. 

Packed vs Plate Columns. Relative to plate towers, packed towers are more useful for multipurpose distillations, usually in small (under 0.5 m) towers or for the following specific appHcations severe corrosion environment where some corrosion-resistant materials, such as plastics, ceramics, and certain metaUics, can easily be fabricated into packing but may be difficult to fabricate into plates vacuum operation where a low pressure drop per theoretical plate is a critical requirement high (eg, above 49,000 kg/(hm ) (- 10, 000 lb/(hft )) Hquid rates foaming systems or debottlenecking plate towers having plate spacings that are relatively close, under 0.3 m. 

Computation of Tower Height The required height of a gas-absorption or stripping tower depends on (1) the phase equilibria involved, (2) the specified degree of removal of the solute from the gas, and (3) the mass-transfer efficiency of the apparatus. These same considerations apply both to plate towers and to packed towers. Items 1 and 2 dictate the required number of theoretic stages (plate tower) or transfer units (packed tower). Item 3 is derived from the tray efficiency and spacing (plate tower) or from the height of one transfer unit (packed tower). Solute-removal specifications normally are derived from economic considerations. 

Weir height is less than 15 percent of plate spacing... 

Comparison of Efficiency of Various Plates Several studies of various plates have been carried out under conditions such that direct and meaningful comparisons are possible. Required conditions include identical system, same pressure, same column diameter, and equivalent submergence. Standart and coworkers [B/ Chem. Eng., 11 (11), 1370 (1966) Sep. Sci, 2, 439 (1967)] used the methanol-water system at atmospheric pressure in a 1.0-m (3.3-ft) column. For a plate spacing of 0.4 m (15.7 in) they studied the following ... 

Billet and cowodcers [Chem. Jng. Tech., 38, 825 (1966) Jnstn. Chem. Engrs. Symp. Set No. 32, 5, 111 (1969] used the ethylbenzene/ styrene system at 100 torr and a 0.8-m column with 500-mm plate spacing. Two weir heights were used, 19 and 38 mm. Operation was at... 

Column diameter in. Amplitude, in. Plate spacing, in. Agitator speed, strokes/min Extractant Dispersed phase Minimum HETS Throughput, gal hr- ft-2 Volumetric efficiencies V/HETS,h" ... 

Curve No. Column diam, in phase dispersed phase extractant Double amplitude, in Plate spacing, in Total throughput gal/(li)(fr)... 

The following parameters are kept constant on the scale-up total throughput per unit area, plate spacing, and stroke length. The... 

For two-stage precipitators with close collec ting-plate spacings (Figs. 20-152, 20-153), the gas flow is substantially streamline, and no 01001 110 wind exists. Consequently, with reentrainment neglected, collec tion efficiency may be expressed as [Penny, Electi Eng, 56, 159 (1937)]... 

Figure 2.20 Austenitic stainless steel plate from plate-and-frame heat exchanger. The orange oxide was formed from corrosion product originating at the regularly spaced pits. Pits are present near points of contact between adjacent plates. Corrugations run at right angles on adjacent plates.

Ward [187] reports the best fits for the curves at tray (or plate) spacing in the range of 0.5 to 3.0 feet, and at the ends of the curves. 

Liquid entrainment mass velocity corrected for liquid properties and plate spacing, lb entrainment/(hr) (ft ), based on net tray area as for Wg... 

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