Fractional approach to flooding

Ada Downcomer apron area m2 ft2 f Fractional approach to flood -/- -/-... 

Dg, Dl = vapor and liquid phase diffusion coefficients, m /s liL = liquid holdup, mm / = fractional approach to flood Fya = active area F-factor, Uap (active area = bubbling area of tray)... 

We will repeat the estimation of the numbers of transfer units using the Chan and Fair correlation for the number of transfer units for the vapor phase. The fractional approach to flooding is... 

In this expression, the volumetric mass transfer coefficient is in reciprocal seconds, the molecular diffusion coefficient in m2/s, and the liquid holdup h L in meters. The term F refers to fractional approach to flooding. 

Usually, packed columns are designed based on either of two criteria a fractional approach to flooding gas velocity or a maximum allowable gas-pressure drop. For given fluid flow rates and properties, and a given packing material, equation (4.8) is used to compute the superficial gas velocity at flooding, vGF. Then, according to the... 

Typically, the column diameter D is based on a specified fractional approach to flooding/ Then,... 

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 ... 

Run the sieve-tray design program of Appendix E using these data. Try different values of the fractional approach to flooding,/, until the program converges to the specified tower diameter D = 1.036 m. When convergence is achieved, the results at the top of the tower are ... 

Fractional approach to flooding, defined by Eq. (7.20). Flow, th length (distance from the inlet downcomer edge to outlet weir), in. 

Use one pass, tray spacing (0.6096 m), minimum downcomer area (0.10), foaming factor (1), and over design factor (1). Set the fractional approach to flooding at 0.7. Use the Fair design method for flooding.]... 

FRACTIONAL APPROACH TO FLOOD FIGURE 5.7-7 Chart for estimating height of froth on sieve trays. 

---