Transition tray

Refinery Presumably a fixtctionator A restrictive design of a transition tray converting sin e-pass flow to two-pass flow caused premature flooding. Avoid restrictive transition tray designs. 

Thermoforming of extmded sheet is achieved by warming the sheet to its glass-transition poiat and coUapsiag it over a mold shape (21). The coUapse can be effected by vacuum suction or pressures appHed on the sheet above the mold. This technique is used to make trays and profiled advertisiag signs. Both single- and multilayer sheets can be used. 

Valve Trays The amount of work reported thus far on valve tray regime transition is small and entirely based on air-water tests. Correlations proposed to date require the knowledge of liquid holdup at transition, which is generally not available, and are therefore of limited application for commercial columns. 

Effect of fractional hole area. Low fractional hole areas increase the tendency of trays to operate in the spray regime (92,106), In terms of Fig. 6.29, lower fractional hole areas tend to shift the spray-froth boundary to the right. No effect of fractional hole area was observed (17,85) on the transition from the froth to the emulsion regime. 

Froth-spray. Froth-spray transition has been investigated for sieve trays using a variety of techniques (12,24,88-92,103,108-110). The gradual nature of this transition bred a large number of criteria for defining it, and made its correlation difficult. Excellent overviews of the state of art were given by Lockett (12) and Prado and Fair (103). 

An early study (91) reports that a correlation derived by Barber and Wijn for sieve tray froth-to-spray transition is also applicable to valve trays. A more recent study by Dhulesia (112) disagrees, and reports that valve trays have a stronger tendency to operate in the froth regime than sieve trays. Dhulesia proposed an alternative froth-spray transition correlation for valve trays, but this correlation is based on air-water data from a single type of valve tray, and its extension to other situations has not been tested. 

Flow regime. Since the trays are unlikely to operate in the spray regime (Sec. 6.4.2), it is best to first examine the froth-emulsion transition. This check requires using the Hofhuis correlation for clear liquid height (Sec. 6.3.5). 

Ponchon-Savarit diagram. 26 Ponter underwetting theory, 516, 517 Porter rivulet model. 542 Porter and Jenkins packing HETP, 532-534 regime transition. 332 Poynting factor. 7 Prado and Fair tray efficiancy, 375 PRO/II. 169, 170,180... 

For agricultural markets, NNZ supplies film and bags, trays and containers, transit packaging, net packaging, paper and cardboard packaging and jute sacks. 

While lyophilizing ampoules on trays under maximum vacuum, we have effectively observed a prolongation of primary drying by 20-30% under partial load conditions. However, in no case was an increase in product temperature noticeable, even when the transition ramp to secondary drying was started before completion of product primary drying. 

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