Fractional entrainment

Figure 18 is an entrainment or gas-carryiag capacity chart (25). The operating conditions and particle properties determine the vertical axis the entrainment is read off the dimensionless horizontal axis. For entrainment purposes, the particle density effect is considered through the ratio of the particle density to the density of water. When the entrainable particle-size distribution is smaller than the particle-size distribution of the bed, the entrainment is reduced by the fraction entrainable, ie, the calculated entrainment rate from Figure 18 is multipfled by the weight fraction entrainable. 

Entrainment can be estimated from the correlation given by Fair (1961), Figure 11.29, which gives the fractional entrainment tfr (kg/kg gross liquid flow) as a function of the liquid-vapour factor Fiv, with the percentage approach to flooding as a parameter. 

P, Pt Total pressure kPa atm V Fractional entrainment, moles liquid k-mol/ lb-mol/... 

Reference A3 (Figure 11.29) predicts a fractional entrainment of approximately 0.005. From Ref. A5 (Figure 3), the fractional entrainment is 40% lower than the limiting value for this plate separation distance of 0.5 m. This implies entrainment should not present any problems. 

Section 6.2.11 recommends the use of Fair s entrainment correlation in the froth (and emulsion) regime. This section also states that entrainment in the emulsion regime is unlikely to be a problem. Fair s correlation (Fig. 6.16) predicts fractional entrainment (pound of entrained liquid per pound of liquid) of 0.0 ll and 0.0075 at 80 percent of flood for the top and bottom trays, respectively. Even at 90 percent of... 

But only a fraction of these particles will be entrained, while the remainder will rebound due to impact with particles already in the spout. If it is further assumed that the number of type-2 particles per unit spout height is the same as the number of type 1, the fraction entrained will equal (e. — ea)/(l — Ca). Combining this condition with Eq. (58) gives the rate of actual cross-flow from the annulus into the spout ... 

Figure 8-138. Fractional entrainment, sieve 1 trays. Used by permission, Fair, J. R., Petro/ Chem. Engineer, Sept. (1961), p. 45, reproduced by courtesy of Petroieum Engineer International, Dallas, Texas.

Liquid entrainment can adversely affect the tray efficiency. As liquid is entrained from one tray to the tray above, the entrained liquid, e, joins the normally flowing liquid, L, resulting in a total liquid flow of L + e. The fractional entrainment z is deflned as the ratio of entrained liquid to total liquid flow ... 

At high vapor rates, entrainment becomes significant and decreases tray performance. To take this into account, Bennett et al. (1997) defined the fractional entrainment E as... 

E fractional entrainment liquid mass flow rate/gas mass flow rate. E extract mass flow rate, kg/s. 

Mechanically each of such apparatuses consists of contact channel fractionally entrained in a fluid and the drip pan merged in one body. The principle of act of apparatuses is grounded on a way of intensive wash down of gases in contact chaimels of a various configuration with the subsequent separation of a water gas flow in the drip pan. The fluid which has thus reacted and separated from gas is not deleted at once from the apparatns, and circulates in it and is multiply used in dust removal process. 

Fractional entrainment limit, limit on heat flux on the reboiler and limits on the utility flowrates ... 

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