Empty-tower velocity

Equations (33) - (35) are taken from Tardos et al (23), and are based on a low Reynold s number analysis. Eqn. (33) is the result of a "best-fit" of the theoretically computed values taken from Figure 7 of that same work. Similarly, Eqn. (36) for the electrical deposition, is obtained from a "best-fit" of the theoretically computed values taken from Figure 3 of Tardos and Pfeffer (21). Note that if the particle and collector charges are of the same sign, the electrical deposition efficiency becomes the negative of Eqn. (36). Consistent with the flow field models used in the development of Eqns. (33) - (36), the velocity employed is an assembly averaged velocity for each phase. For the multi-phase situation that exists in the fluidized bed, this is given by the superficial or empty-tower velocity divided by the phase volume fraction, ... 

The pressure drop depends on the average velocity in the channels V, which is proportional to the superficial or empty-tower velocity Fq and inversely... 

Volumetric average fluid velocity, m/s or ft/s V, critical wlocity in hydraulic transport Vq, superficial or empty-tower velocity minimum superficial velocity for fluidization Volume of single particle, ft or m ... 

Air velocity in pneumatic conveying (L/T), superficial velocity or empty-tower velocity (L/T)... 

V = superficial linear gas velocity (based on cross-sectional area of empty tower), ft/s... 

V = superficial linear gas velocity based on empty tower = 1.8 ft/s WT = average tray width perpendicular to direction of fluid flow = 9 ft Ql/wt = = O.lll ft3/(sXft)... 

A sieve-tray tower has an ID of 5 ft, and the combined cross-sectional area of the holes on one tray is 10 percent of the total cross-sectional area of the tower. The height of the weir is 1.5 in. The head of liquid over the top of the weir is 1 in. Liquid gradient is negligible. The diameter of the perforations is in., and the superficial vapor velocity (based on the cross-sectional area of the empty tower) is 3.4 ft/s. The pressure drop due to passage of gas through the holes may be assumed to be equivalent to 1.4 kinetic heads (based on gas velocity through holes). (Tray thickness = hole diameter and active area = 90 percent of total area-see Fig. 16-12). If the liquid density is 50 lb/ft3 and the gas density is 0.10 lb/ft3, estimate the pressure drop per tray as pounds force per square inch. 

G = superfieial mass velocity of gas (based on eross-seetional area of empty tower), lb/(hXft )... 

D20/day How many columns 3 m in diameter must be used in parallel on the feed stage if the maximum vapor velocity based on the empty tower is 1 m/s ... 

Linear velocity in vertical direction (L/T), upwards or downwards velocity in the open section below the grid or in empty tower above bed (L/T), fluid-particle relative velocity (L/T), settling velocity at concentration C (L/T)... 

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