Flood trays weir length

Effect of column diameter (at constant UV and percent of flood). As column diameter increases, both the liquid and vapor flow rates increase as the square of the diameter. The area for vapor flow also increases as the square of the diameter, so the vapor load remains unaffected. On the other hand, the area available for liquid flow only increases in proportion to the diameter. Therefore, the liquid rate per unit of weir length increases, the increase being proportional to the column diameter. The operating point on Fig. 6.29 will therefore shift horizontally to the right, toward the emulsion regime. Increasing the number of liquid passes on the tray reverses the above action, and shifts the operating point back to the left. 

Tray type Weir height Weir length Downcomer clearance Tray spacing Foaming factor Fraction of flood Surface tension Liquid viscosity... 

Wl is weir liquid loading in gpm/in. while L is the outlet weir length. Equation (12.19) states that both vapor and liquid loading contribute to tray flood although... 

Weir loading in U.S. gallons per minute (GPM) per inch of weir length should be kept between 3 and 12. Above 13 or 14, a loss of tray efficiency due to entrainment (i.e., jet flood) can be expected. Below 3 GPM per inch of weir, the liquid flow across the tray will not be particularly uniform and a loss in tray efficiency will result. 

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