Sieve-Tray Design Program

This program calculates the diameter of a sieve-trey tower to satisfy an approach to flooding criterium, and estimates the trey efficiency. The data presented are from Example 4.10 

Enter liquid flow rate, mL, in kg/s Enter gas flow rate, mG, in kg/s 

Enter data related to the tray design Enter hole diameter and pitch 

Specify the ratio of downcomer area to total area, AdAl 

Use is made here of the step function X ()0 to define the recommended values of tray spacing according to Table 4.3. 

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Run the sieve-tray design program of Appendix E using these data. The program converges to a tower diameter D = 1.036 m and a tray spacing t = 0.6 m. When convergence is achieved, the results at the bottom of the tower are ... 

As you can see in Tables 3.6 and 3.7, the valve, bubble cap, and sieve trays share many of the same input prompts in the tray design programs supplied on the accompanying CD. 

Next, enter the data presented above into the Mathcad sieve-tray design computer program of Appendix E. Since the dimensions of the tray are known, the fractional approach to flooding is adjusted until the tray design coincides with the tray dimensions determined in part (a) of this example. Convergence is achieved at a value of/= 0.431. This means that at the bottom of the distillation column the gas velocity is only 43.1% of the flooding velocity. Other important results obtained from the program are as follows ... 

Fig. 3.1. Also note that this nonconventional design has the downcomer outlet area as additional active tray area. This additional active area is the tray deck area under the downcomer having valves, bubble caps, or sieve holes that allow the gas to pass through under the liquid downcomer area of the next tray up. ICPD tray programs dealing with the design and rating of sieve, bubble cap, and valve-type trays allow this active area input. This is an option shown in Table 3.1, which is offered in the three tray design/rating computer programs given in this book.

Due to the need to use case-by-case analysis the Kister studies [136, 137] focused on item 1. The data evaluated came from published reports by Fractionation Research (FRI) and Separation Research Program (SRP) at the University of Texas, taken from commercial size equipment rather than laboratory research columns. The FRI data includes No. 2 and No. 2.5 Nutter random rings packing, aind Norton s Intalox 2T structured packing, each considered currently state-of-the-art or close to it, while the sieve and valve trays were of FRI s latest designs, plus Nutter s proprietary valve trays, all using 24-in. tray spacing. 

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