Flood trays hole diameter

C C-factor (describing vapor load) ft/s CFS vapor flow ft /s Cp C-factor at flood ft/s 4i tray hole diameter in. 

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. 

Hole Sizes Small holes slightly enhance tray capacity when limited by entrainment flood. Reducing sieve hole diameters from 13 to 5 mm ( to in) at a fixed hole area typically enhances capacity by 3 to 8 percent, more at low liquid loads. Small holes are effective for reducing entrainment and enhancing capacity in the spray regime (Ql < 20 m3/hm of weir). Hole diameter has only a small effect on pressure drop, tray efficiency, and turndown. 

Downcomer cross-sectional area Total hole area Parameter in Equation 14.1 Drag coefficient Entrainment flooding capacity Orifice coefficient Tray diameter Hole diameter... 

Sieve trays will be used with 60 cm spacing, 6 cm weir height, 0.6 cm hole diameter, 0.25 cm tray thickness, 5 cm downcomer clearance, and hole area 10% of the total tray area. The foaming factor is 0.80 and the froth density in the downcomer is 0.5. The target fraction of flood velocity is 0.70. 

Tray hole area is consistent with the design value. Care should also be taken to ensure that the holes are of consistent diameter, and that blanking strips (Sec. 6.4) are correctly positioned. The author is familiar with a case where one tray with a grossly diminished hole area was enough to prematurely flood an entire column. Hole, riser, and/or weep hole areas should be checked in a similar manner in distributors, redistributors, parting boxes, and chimney trays. 

Sieve trays with 10% hole area and 0.5 cm diameter holes will be used. Trays are available in standard diameters of 0.25 m increments (0.25,0.50, 0.75, 1, 1.25, 1.50,. .., m). Based on the top tray conditions, determine the required tray diameter rounded up to the nearest larger standard size. Assume a tray spacing of 0.5 m, a foaming factor of 0.80, and a fraction of flood of 0.80. The liquid density is given as 730 kg/m and the vapor density may be estimated based on the ideal gas equation. The liquid surface tension is 27 dynes/cm. 

The column has 3 m diameter sieve trays with 0.5 cm diameter holes and 10% hole area. The tray spacing is 45 cm. Assuming a foaming factor of 0.85, calculate the vapor flood velocity at the top tray. Check if the column diameter is acceptable. The fraction of flood velocity should be within a 60-85% range. 

If sieve trays are used with hole area of 10% and a 24-in. tray spacing, determine the tower diameter. Assume 80% of flooding and a foaming factor of 0.75. 

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