Redistribution plates

Pressure Drop Across Packing Supports and Redistribution Plates... 

Useful correlated information on pressure drop across packing supports and redistribution plates is practically not available. Some order of magnitude guide data is given in Figures 9-37-41. 

This bed should be in three sections (two might be acceptable under some circumstances, or if different packing were used) thereby requiring two intermediate combined packing supports and redistribution plates and one bottom support plate. 

While the circumstances of operation of such a device might seem to permit direct application of the results obtained on small columns to large ones, there are apparently some difficulties. In columns as large as 24 in. in diameter, for example, considerable channeling may be observed, and this may lead to as much as a 50% decrease in extraction efficiency (W2). For such columns, special redistribution plates have been developed which overcome this tendency (W2). 

The column length should be evaluated very prudently because axial mixing increases with the increase in column diameter. Great care must be taken to design the fluid and liquid phase distributors channeling will be reduced by fractionating the packing in several beds separated by redistribution plates. 

Phj sically the redistributions may be a simple and relatively inefficient side wiper as in Figure 9-12 or 9-13 a conventional support grid or plate plus regular distribution plate as used at the top a combination unit similar to Prym support and distributor or a support plate as shown in Figures 9-14 and 9-7D and 7E, a circular plate with holes. 

The possibility of causing flooding in the tow er at the redistribution point must not be overlooked, as too much restriction by a wall wiper, or by packing on a plate can be the focal point for poor tower performance. The velocity conditions should be checked for the smallest cross-section. 

Redistribute the liquid every 10 ft and allow 2 ft additional for redistribution = 36 ft. Then use 4-10 ft sections of packing. For 20 theoretical plates, total performance packed height 20 (18 in./12 in.) = 30 ft. Allow for loss of equilibrium at (1) reflux entrance = 1 HETP and (2) feed entrance = 2 HETP and (3) redistribution (2) = 2 HETP totals 5 HETP. 

This model does not explicitly consider that a fraction of the measured Pb-214 actually deposits in the impactor as particle-associated Po-218. The Pb-214 daughters produced under this condition would either not recoil off the plate or, if they did, they might end up associated with a smaller size fraction on a lower stage. In terms of both the model and the measurements, this fraction of the total Po-218 is not operationally different from the fraction which decays before attachment (1-A) or is not lost following recoil both represent Po-218 which does not undergo recoil redistribution. 

An electrical double layer is usually formed at a semiconductor-electrolyte interface, as well as at the boundary between two solids. This layer consists of plates carrying opposite charges, each being located in one of the phases in contact. In the semiconductor the charge in the region near the surface is formed due to redistribution of electrons and holes in the electrolyte solution, due to redistribution of ions, which form the ionic plate of the double layer. 

Unfortunately, packing does not redistribute liquid, or internal reflux. Unless the initial reflux distribution is good, the liquid flow distribution through the entire packed bed will be poor. Figure 7.1 shows a common orifice plate liquid distributor. Vapor flows up through the large chimneys, and liquid drains through the smaller distribution holes in the tray deck. 

We know that C6-cyclization of 1-(naphthyl-2)-butene is possible without metal catalysts. The products are dihydrophenanthrene over quartz and 1,2,3,4-tetrahydrophenanthrene plus phenanthrene over alumina (50). The latter apparently catalyzes the redistribution of hydrogen in dihydrophenanthrene. Neither anthracene nor dihydro- or tetrahydroanthracene are formed over quartz or alumina from 1-(naphthyl-2)-butene. Plate and Erivanskaya concluded from this that the 2-alkylnaphthalene - anthracene reaction does not involve naphthylbutene intermediate (27). 

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