Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Downcomer sloping

Conventionally, most downcomers are sloped (see Fig. 3.4). A 70% downcomer slope is normal convention. This means the area of the bottom of the downcomer is 70% of the area of the top of the downcomer. The program supplied with this book makes a conservative calculation,... [Pg.83]

Downcomer sloping. Sloped downcomers are often used to permit a greater perforated tray area while maintaining a high downcomer entrance area, needed to prevent downcomer choke. [Pg.23]

When downcomers are sloped or when perforations do not occupy essentially all the area between the downcomers, these simple relations do not apply. However, their adaptation should be obvious from the geometry involved. [Pg.1371]

Here is a tip for possible capacity increase for towers with sloped downcomers. Usually, the tray vendor doesn t use the dead area next to the bottom part of the sloped downcomer as active area if the trays are multipass, since he would require a different design for alternate trays. This area could be used for additional vapor capacity in an existing column. [Pg.302]

FIG. 14-23 Common downcomer types, (a) Segmental, (b) Circular, (c, d) Sloped. (From Henry Z. Kister, Chem. Eng., December 29, 1980 reprinted courtesy of Chemical Engineering.)... [Pg.32]

M slope ratio—derived Y-axis vapor phase first factor M slope ratio—derived Y-axis vapor phase second factor downcomer chord/2, ft... [Pg.69]

Each downcomer of each tray must have the same rate of liquid per downcomer area as all other downcomers on the tray. (Area here refers to the top of the downcomer section, in the case of sloped downcomers.)... [Pg.71]

Slope downcomers (Y/N) N Side dcmr. area (opt.), ft2 0 Active area (opt.), ft2 0 Flow path length (opt.), in 0... [Pg.73]

Sloped downcomers (Y/N) N Number of passes 4 DC backup, in 10.87 Gas rate, lb/h 8.4500e + 04 Tray active area, ft2 30.426 Center DC area, ft2 7.671 Center DC width, in 11.41 Tray press, loss, in 4.76... [Pg.73]

System factor 0.95 Tray spacing, in 24 Actual vapor density, lb/ft3 0.2 Gas molecular weight 21 Liquid density, lb/ft3 44 Gas rate, lb/h 8.4500e + 04 Liquid rate, lb/h 7.4500e + 05 Slope downcomers (Y/N) N Side downcomer area (opt.), ft2 0 Active area (opt.), ft2 0 Flow path length (opt.), in 0... [Pg.74]

All trays must have a balance of downcomer areas. Notice that the areas of the two side downcomers on any tray (straight downcomers, not sloped) are nearly equal area to that of the center downcomer. In other words, the area of the center downcomer tray approximately equals the area of two side downcomers. The logic here is that the liquid backup height in all downcomers must be equal, or otherwise the choked downcomer (the one having a lesser area) will flood, causing tray failure. [Pg.75]

Tlay Spacing, Inches FPL, Inches [24 1 Sloped Downcomers (Y/N) No. Passes ... [Pg.82]

A downcomer must be sufficiently large to transport all of the liquid downflow without choking. If the friction losses in the downcomer and or downcomer entrance are excessive, liquid will back up onto the tray and eventually flood the column. This is termed downcomer choke. The prime design parameter is the downcomer top area, where friction losses are highest- Further down the downcomer, vapor disengages and the aerated liquid downflow is greatly reduced. With sloped downcomers, the downcomer bottom area is normally set at about 1.7 to 2 times less than the area at the top of the downcomer (1,8,9,10,48). This taper is small enough to keep the downcomer top area the prime downcomer choke variable. [Pg.288]

Downcomer layout The total tower area of a 6.5-foot tower is 33.2 ft8. In the top section, downcomer area is 8.6 ft2, i.e., the downcomer is about 3.8/33.2 11,5 percent of tower area. This is a relatively small fraction, and there is little incentive to reduce it further. On the other hand, in the bottom section the downcomer occupies 3.5/33.2 = 25.6 percent of the tower area. There is an incentive to reduce this area by using a sloped downcomer. A 2 1 top-to-bottom area ratio is appropriate (1). Therefore, downcomer top area in the bottom section is 8,5 ft2, while downcomer bottom area is 3.5/2 = 4.25 ft . In summary... [Pg.341]

When dealing with foaming or high-pressure systems, a frequent recommendation is the installation of sloped downcomers. This provides for adequate liquid-vapor disengaging volume at the top, while leaving a maximum active area on the tray below. [Pg.360]

The segmental, or chord downcomer, shown in Figure 11.26a is the simplest and cheapest form of construction and is satisfactory for most purposes. The downcomer channel is formed by a flat plate, called an apron, which extends down from the outlet weir. The apron is usually vertical but may be sloped (see Figure 11.26b) to increase the plate area available for perforation. If a more positive seal is required at the downcomer at the outlet, an inlet weir can be fitted (see Figure 11.26c) or a recessed seal pan used (see Figure 11.26d). Circular downcomers (pipes) are sometimes used for small liquid flow rates. [Pg.715]

It is a common practice, as shown in Fig. 1, to slope the downcomer wall inward so that the bottom of the... [Pg.269]

For sloped downcomers adjust W (weir length) to the correct value for the downcomer bottom edge. Downcomer clearance, //dcc, is typically a minimum of lin. (25.4 mm) and is usually 0.5 in. (12.7 mm) less than the outlet weir height to maintain a positive seal on the downcomer. Calculate the velocity under the downcomer ... [Pg.757]

Multichordal downcomers can increase weir length (Fig. 6). Fig. 6 shows a combined multichordal and stepped downcomer. The increased weir length decreases the liquid crest height over the weir. This decreases total tray pressure drop. The stepping is a variation of a sloped downcomer. The step increases the downcomer inlet area with a minimum decrease in tray active area. [Pg.758]


See other pages where Downcomer sloping is mentioned: [Pg.31]    [Pg.84]    [Pg.1584]    [Pg.1580]    [Pg.31]    [Pg.84]    [Pg.1584]    [Pg.1580]    [Pg.1375]    [Pg.177]    [Pg.564]    [Pg.34]    [Pg.40]    [Pg.76]    [Pg.79]    [Pg.79]    [Pg.80]    [Pg.81]    [Pg.81]    [Pg.83]    [Pg.362]    [Pg.1194]    [Pg.1198]    [Pg.563]    [Pg.177]    [Pg.1587]    [Pg.1593]    [Pg.758]    [Pg.759]    [Pg.761]   
See also in sourсe #XX -- [ Pg.341 ]




SEARCH



Downcomer

Downcomer tray sloped

Downcomers

Slope

Slope downcomer

Slope downcomer

Sloped downcomer

Sloped downcomer

Sloping

© 2024 chempedia.info