Entrainment comparison

Figure 8-139. Entrainment comparison sieve trays vs. bubble caps for 24-in. tray spacing. Note BCT = Bubble Cap Tray ST = Sieve Tray FP = Flow Parameter. Used by permission, Fair, J. R., Petro-Chem Engineer, Sept. (1961), p. 45, reproduced courtesy of Petroleum Engineer International, Dallas, Texas.

In comparison, units that are designed with turbulent beds have a lower superficial velocity limit because of soflds entrainment and are unable to independently control the entrained soflds recycle. The soflds loading in the turbulent-bed regenerator configuration are equal to the reactor—regenerator circulation plus the entrained soflds via the cyclone diplegs. 

The calculated entrainment values may be as good or better than measured values [183]. Figure 8-139 illustrates comparison of entrainment between bubble cap and sieve trays. Fair [183] concludes that for vacuum to moderate pressure applications, sieve trays are advantageous from an entrainment-flooding stand-point. 

Sutherland [69] reports for air-water entrainment of 0.0001 to 0.1 lb liquid/lb vapor, averaging 0.01 for 15-in. tray spacing at hole velocity Fj values of 3 to 15. Fh = Vq These values are 1-10% of bubble cap plates. Simkin et al., [64] reports a comparison with the Turbogrid tray giving only 3-60% of the entrainment of bubble caps over a wide range of operation. 

Air/water vapor mixture, chart, 364,365 Air/water vapor, 359 Capacity at ejector suction, 369 Capacity for process vapor, 362 Evacuation time, 371, 380 Load for steam surface condenser, 367 Non-condensables, 362, 363 Size selection, 371 Steam pressure factor, 373 Steam requirements, 372 Steain/air mixture temperature, 361 Total weight saturated mixture, 362 Capacity, 358 Discharge, pressure, 358 Effect of excess steam pressure, 358 Effects of back pressure, 359 Effects of wet steam, 356 Inter-and-after condenser, 351 Load variation, 370 Materials of construction, 347 Molecular weight entrainment, chart, 360 Performance, 358, 370, 375 Relative comparison, 357... 

Both Eq. (144) and Eq. (145) give values higher than the observed data, in particular for water-glycerol systems containing lower concentrations of glycerol. It should be mentioned that, in this comparison with experiment, the assumption is made that the suspended bubbles entrained by the fluid, which describe complicated trajectories in the fluid, are moving relative to the... 

Figure 5.3e shows the situation when the air velocity was increased to Ugs = 20 m/s. It is seen from this figure that the liquid bridges in churn flow disappeared and a liquid film formed at the side walls of the channel with a continuous gas core, in which a certain amount of liquid droplets existed. The pressure flucmations in this case became relatively weaker in comparison with the case of the churn flow. The flow pattern displayed in Fig. 5.3f indicates that as the air velocity became high enough, such as Ugs = 85 m/s, the liquid droplets entrained in the gas core disappeared and the flow became a pure annular flow. It is also observed from Fig. 5.3f that the flow fluctuation in this flow regime became weaker than that for the case shown in Fig. 5.3e, where Ugs = 20 m/s. 

The combustion efficiency of the benzene was beyond 99.999% even at an overall equivalence ratio of 1.0 (including the entrainment air which was 30% of the total air flow). With the controller off, the flame was extremely sooty and, in fact, sooting as the quartz tube would be blackened and the mass spectrometer sampling probe clogged in a matter of seconds, and soot was sucked into the scrubber system. This comparison between controller off and controller on conditions with benzene fuel is extremely dramatic and shows the efficacy of active combustion control in vortices to eliminating soot from diffusion flames. 

Figure 11.5 Comparison of computed entraining velocity fields at the widest transverse sections of the (a) unheated and (6) heated jet at time t = 35. The contonrs of streamwise vorticity, at intervals of 0.5, are shown using solid lines for positive values, and dotted lines for negative values. Contour for level 0 is not shown... 

Fig. 3.12 Comparison of the air-entraining capacities of sodium and calcium abietates. O = sodium abietate dissolved in mixing water and added to cement = made with filtrates from mixtures of sodium abietate and cement paste extract (Bruere). 

Table 6.3 Comparison of expansion of mortars containing silica fume and air-entraining agent (Ramachandran)...

In a series of experiments we have tested the type and range of entrainment of glycolytic oscillations by a periodic source of substrate realizing domains of entrainment by the fundamental frequency, one-half harmonic and one-third harmonic of a sinusoidal source of substrate. Furthermore, random variation of the substrate input was found to yield sustained oscillations of stable period. The demonstration of the subharmonic entrainment adds to the proof of the nonlinear nature of the glycolytic oscillator, since this behavior is not observed in linear systems. A comparison between the experimental results and computer simulations furthermore showed that the oscillatory dynamics of the glycolytic system can be described by the phosphofructokinase model. 

Elmore, J.S., Papantoniou, E., and Mottram, D.S. 2001. A comparison of headspace entrainment on Tenax with solid phase microextraction for the analysis of the aroma volatiles of cooked beef. Adv. Exp. Med. Biol. 488 125-132. 

For aged samples, it is often necessary to repeat the extraction steps more than once for complete recovery. The analogous classical extraction comparison would be the introduction of a second liquid phase in a separatory funnel extraction. However, because of our automated system, the introduction of a second or third extraction step is conducted easily. The modifier/entrainer can be independently introduced to the matrix without interrupting the extraction procedure. In the time estimates given for the diuron spiked Tama soil extractions, two extractions per vessel were conducted. This resulted in 3 hours for the extraction of six samples in the six vessel extractor as well as 3 horns for twelve samples in the twelve vessel extractor since the extractions are conducted in pairs. 

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