Tray design

Ballast Tray Design Manual, Bulletin 4900, GUtsch, Inc., DaUas, Tex., 1974. 

Float Valve Tray Design Manual, Nutter Engineering Co., Tulsa, OHa., 1976. 

High-hqiiid holdup trays designed with catalyst bed extending None specified Yeoman et al., Int. Pat. Appl., WO 9408679... 

Tbe best-established theoretical method for predicting E is that of tbe AlCbE [Buhhle-Tray Design Manual, American Institute of Chemical Engineers, New York, 1958). It is based on tbe sequential prediction of point efficiency, Murpbree efficiency, and overall column efficiency ... 

FIG. 14-39 Mixing curves. Pe = Peclet niimher (Npe). (Biihhle-Tray Design Manual, Ameiican Institute of Chemical Engineers, New Yoth, 1958. )... 

Fair s empirical correlation for sieve and bubble-cap trays shown in Fig. 14-26 is similar. Note that Fig. 14-26 incorporates a velocity dependence (velocity) above 90 percent of flood for high-density systems. The correlation implicitly considers the tray design factors such as the open area, tray spacing, and hole diameter through the impact of these factors on percent of flood. 

GUtsch Ballast Tray Design Manual, 5th Ed. Bulletin No. 4900, Copyright 1974, Glitsch Inc. 

Many columns have water removal trays designed into the column. Top or bottom temperatures may have to be changed to expel the water if the column isn t provided with water removal trays. In some instances, the water can be expelled by venting the column through the safety relief system. 

HETP for a 2-in. slotted metal ring in a condensate stabilizer is about 36 in. This is slightly more than a typical tray design, which would require 34 in. (1.4 trays X 24-in. tray spacing) for one theoretical plate or stage. 

Efficiency most data are for this type, as high as other tray designs. 

Flexibility most flexible of tray designs for high and low vapor and liquid rates. Allows positive drain of liquid from tray. Liquid heads maintained by weirs. 

This specialized Sieve Tray design is of high efficiency and operates with exceptional short tray spacings, sometimes as low as 6 in. between trays. 

There are many special tray designs which solve special problems and exceed the capabilities of the conventional trays. The comments regarding performance are those claimed by the manufacturer, see Table 8-12. 

Not all tray designs solve special problems, even though some may have unique performance features. Most of... 

Each tray design should ultimately resolve and achieve the following ... 

A tray design guide is given in Table 8-15 (page 138) and is as presented by Bolles [5] except with modifications where noted. 

Figure 8-86 (page 139) is a 3-ft 0-in. diameter tray, and is representative of details associated with tray design.A typical 4-in. pressed cap is shown in Figures 8-79 and 81. 

Caps suitable for particular tray designs are shown in Figures 8-87, 88 and 89. The rectangular caps require layouts differing from the bell caps, but similar in design principles of flow path evaluation. 

For tray columns, bubble caps, valves or sieve, the feed liquid usually enters the column either in between functioning trays or at the top (reflux). The liquid or liq-uid/vapor mixture for flashing liquids must be dispersed uniformly across the tray. Such an arrangement often requires a special tray designed for the purpose to allow... 

These contribute to the uniform distribution of liquid as it enters the tray from the downcomer. There are about as many tray designs without weirs as with them. The downcomer without inlet weir tends to maintain uniform liquid distribution itself. The tray design with recessed seal pan ensures against vapor backflow into the downcomer, but this is seldom necessary. It is not recommended for fluids that are dirty or tend to foul surfaces. The inlet weir is objectionable for the same reason. 

The adjustable weir feature of many tray designs allows a standard tray to be utilized in different services by readjusting the weir height as needed. The fixed portion of the weir should never be lower than the top of the slots of the bubble caps. Depending upon service, the adjustable weir... 

The importance of the downcomer seal is to prevent vapor from the tray from bubbling into the downcomer (see Figure 8-63), whether the trays are bubble cap, valve or sieve types. If a seal weir is not included in the tray design, then operation problems to avoid flooding, weeping and unstable performance, including pressure drop, are increased, particularly during the start-up phase. 

For trays with inlet weirs, seal values may be reduced if necessary for high flow conditions. A good tray design is centered about a 1.5-in. clearance distance between tray floor and bottom of downcomer edge. 

Note that this seal varies across the tray, although the tray design must be such as to make the value of hds nearly the same for each row of caps. 

Bubble Cap Tray Design and Evaluation Example S-36 Bubble Cap Tray Design... 

This is not a good tray design, but it should operate. However, a reduced efficiency is to be expected due to low vapor velocities. 

The type tray guide proposed by Huang and Hudson [30] serves to identify the m or breaks in type of tray design (Figure 8-120). In the region between types, the selection is not sharp and the design should be evaluated based on other criteria. 

Tests have indicated that the hydraulic gradient is negligible or very small for most tray designs. Ustial design practice is to omit its effect unle.ss the alue o( A is expected to be greater than 0.75 in. If hydraulic gradient is appreciable, then tbe holes nearer to the tray inlet (liquid) will tend to weep before those nearer the tiay outlet. 

When hydraulic gradient is a factor in the tray design, the dynamic liquid seal should be used in place of hsi for the determination of effective head. 

Example 8-38 Sieve Tray Design (Perforated) with Downcomer... 

The conditions for tray design in a chlorinated hydrocarbon finishing tower are ... 

American Institute of Chemical Engineers, Bubble Tray Design Manual, Prediction of Fractionation Efficiency, Amer. Inst. Chem. Engrs. (1958). 

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