Cut diameter

Fig. 19. Predicted performance cut diameter for typical spray towers (271) (a) vertical countercurrent spray tower (b) horizontal cross-current spray chamber. Liquid—gas ratio is 1 m of Hquid/1000 m of gas. Drop diameter curve 1, 200 p.m curve 2, 500 p.m curve 3, 1000 lm. Uq = 0.6 m/s.

Fig. 21. Performance cut diameter prediction for typical sieve plate operation on wettable particulates at foam densities F solid line, F = 0.4 g/cm, dashed...

Fig. 22. Performance cut diameter predictions for typical dry packed bed particle collectors as a function of bed height or depth, packing diameter and packing porosity (void area) S. Bed irrigation increases collection efficiency or decreases cut diameter (271). SoHd lines, = 25 mm dashed lines,...

FIG. 14-107 Overall integrated penetration as a function of particle-size distribution and collector cut diameter when B = 2 in Eq. (14-224). (Calveti, Gold-shmid, Leith, and Mehta, NTIS Puhl PB-213016, 213017, 1972. )... 

FIG. 14-118 Aerodynamic cut diameter for a single-sieve-plate scrubber as a function of bole size, bole-gas velocity, and froth density, F, g/cm. To convert meters per second to feet per second, multiply by 3.281 to convert grams per cubic centimeter to pounds per cubic foot, multiply by 62.43. [Calveti, J. Air Pollut. Control Assoc., 24, 929 (1974).]... 

FIG. 14-126 Predicted spray-tower cut diameter as a function of sprayed length and spray droplet size for (a) vertical-countercurrent towers and (b) horizontal-cross-flow towers per Calvert [ J. Air Polliit. Control Assoc., 24, 929 (1974)]. Curve 1 is for 200-pm spray droplets, curve 2 for 500-pm spray, and curve 3 for 1000-pm spray. QHQc is the volumetric hqiiid-to-gas ratio, L liqiiid/nri gas, andt/cis the siiperBcial gas velocity in the tower. To convert liters per ciihic meter to cubic feet per cubic foot, multiply by 10 . ... 

Cut diameter, diameter of particles of which 50% of those present are collected m ft im... 

Actual screens do not or provide an incisive separation. Rather, the screen analyses of the overflow and the underflow are like those shown in Figure 2.13 (C). The overflow contains a good amount of particles smaller than the desired cut diameter, and the underflow contains particles bigger than the cut diameter. The two curves overlap, as shown in Figure 2.13 (C). It may also be added that the mass of the two outgoing streams will not equal the individual masses of A and B unless it occurs that the undersize material in the overflow is equal to the oversize material in the underflow. 

The equations derived from consideration of material balances over a screen are found to be useful in calculating the ratios of feed, oversize, and underflow from the screen analysis of the three streams and knowledge of the desired cut diameter. Let F stand for the mass of the feed flow, D for the mass of the overflow flow, B for the mass of the underflow flow, mF for the mass fraction of material, A in feed, mD for the mass fraction of material A in the overflow and mB for the mass fraction of material A in the underflow. The mass fractions of material A are shown in Figure 2.13 (C). The mass fractions of material B in the feed, the overflow, and the underflow are 1 - mF, 1 - mD, and 1 - mn respectively. Since the total material fed to the screen must exit either as underflow or as overflow,... 

A typical plot of efficiency versus particle diameter is shown in Fig. 12-8. This is called a grade efficiency curve. Although the efficiency varies with the particle size, a more easily determined characteristic is the cut diameter (d50), the particle size that is collected with 50% efficiency. 

The residence time is related to the number of turns (AO that the fluid makes in the vortex, which can vary from 0.2 to 10, with an average value of 5. If the 50% cut diameter particle is assumed to enter at (D — b)/2, with a residence time of... 

Calculate the cut diameter. The cut diameter dpc for a given cyclone and given gas to be treated is the diameter of the particle that would be collected at 50 percent efficiency by the cyclone. It can be found from the equation... 

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