K

So the application range of the AIChE method is extended to either for air-water-solid system or for no air-water-solid systems. By combining EQ model and tray efficiency model, much real information on the SCD column, which is necessary for the process design, is obtained. Moreover, tray efficiency can be used for checking the validity of NEQ stage model if the NEQ stage model is readily available, of course.

2.1.2. Hydrodynamics

It is evident that tray hydrodynamics (mainly referring to entrainment, leakage and pressure drop) plays an important role in guaranteeing normal operation of the column with gas-liquid-solid three-phase flow. Unfortunately, no research is yet available for them. The experiments of tray hydrodynamics can be done by use of the same equipment as measuring tray efficiency.

It is found that if the hydrodynamics of gas-liquid-solid three-phase is calculated with gas-liquid two-phase, the error will be great. The ARD between calculated and experimental values is 29.83% for 50 points of entrainment, and 10.25% for 50 points of pressure drop. So it is necessary to re-correlate the mathematics model of entrainment, pressure drop and leakage for gas-liquid-solid three-phase.

After correlating the experimental data, we obtain:

1. For entrainment ev on one tray,

a Ht —hj for w = 0.05, where wa is vapor velocity through the bubble regime (m s"1), HT is tray distance (m), and hf is bubble layer height in the tray (m).

2. For pressure drop on one tray,

where Apc is "dry" pressure drop (Pa), Ap, is "wet" pressure drop (Pa), £=2.1 obtained by correlating the experiment data, hovl is liquid height over the weir (m), m0 is vapor velocity through the hole (m s"1), and ¡3 is coefficient in the "wet" pressure drop.

In Eq. (15), the density of liquid-solid mixture pm instead of p, is adopted, and defined as

Under this condition the ARD of pressure drop is just 5.23% for 50 points. 3. For leakage ratio Q (kg kg"1), it almost remains constant on the tray with raising the concentration of solid phase. The phenomena can be accounted for by the following equation: W

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