The Effect of Solids Loading

Contrary to what one might expect intuitively, cyclone performance improves with increasing solids loading up to quite high loadings the overall efficiency increases, and the pressure drop decreases with increasing solids loading. 

---

It appears that this solids loading of (X = 40, Xy = 0.18, and Fs = 0.42) justifies the use of the more tedious, but more accurate, Chowdhury/Penney/Fasano method for determining the effect of solids loading. 

For gas holdup, bypassing and the effect of solids loading are important issues. Gas holdup increases with solids loading at low solids level, peaks and then decreases with solids content. Gas holdup also... 

The effect of solids loading on hemicellulose hydrolysis was studied by Jacobsen and Wyman (37) and Stuhler (71), Water-only batch tube experiments with com stover were performed at 200°C for 15 minutes at solids loadings of 5 and 21%, and a number of performance criteria including total solids remaining and total soluble xylan oligomer yields were evaluated (71). Statistically significant differences in several results were observed at a 95% confidence level, as summarized in Figure 3. 

Based on criteria cited earlier, polystyrene latex has been identified as a good reference colloid for establishing the proper operation of a microelectrophoresis apparatus. However, the effects of solids loading, electrolyte concentration, and time on p must be determined before reference p values can be established for the colloid. Similar studies should be undertaken when examining any unknown material. When this is done, long-term time-dependent studies can be accomplished with minimal experimental error. 

Effectof Solid Loading. Zwietering chose to represent the effect of solid loading with the parameter X defined above. The exponent on this parameter fits experimental data reliably for values of X from about 5 to 170, which corresponds to about 2 to 40 vol% by volume for sand at a solid density of 2600 kg/m. ... 

Choudhury (1997) and Choudhury et al. (1995) questioned the appropriateness of the use by Zwietering of the X parameter to correlate the effect of solid loading. They preferred the use of Ihe volume fraction as a percent, %V, because a designer can specify it directly. The following expressions are useful for converting between various measures of solid loading in a slurry. To convert from volume percent, vol %, use... 

The objective of this work is to investigate the effects of solids loading on the motion of particles and the modulation of turbulence in the gas-phase. The particle size chosen is typical of that found in fluidized catalytic cracking (FCC) units, coal combustors, and many other processes. The details of the flow behavior for pneumatic conveying operations for this range of particle sizes and for mass loadings above one have not been previously studied. 

Figure 3 displays the effect of solids loading on the particle fluctuating velocities at the centerline. As stated previously, the solids loading was increased by applying a pressure head to the hopper while maintaining a constant volumetric flow of air (5scfm). The r.m.s. values of both the axial and radial fluctuations, Up and Vp, respectively, decrease initially for... 

In general, wall friction has a profound effect on the flow in cyclones and on cyclone performance. We shall discuss this in Chap. 5, when investigating the effect of cyclone body length on cyclone pressure drop and separation efficiency. We shall also discuss the effect of friction in Chap. 9 when looking at the effect of solids loading, which also turns out to be a consequence of the effect of the solids on the wall friction. 

The author s experience is (and the second example in Appendix 6.A also indicates this) that the modeling of the effect of solids loading in some cases may improve by assuming some classification of the material separated in the inlet region due to the effect of loading. However, to be consistent with practice, the cut in the inlet region would have to be very shallow. 

Fig. 9.1.3. The graphical model of Zenz for estimating the effect of solids loading on cyclone separation efficiency. 1 grain/ft = 2.29 g/m ...

Much less experimental data are available on the effect of solids loading on the separation efficiency of swirl tubes with swirl vanes. If the effect of solids loading is indeed one taking place in the inlet region of tangential inlet cyclones, we might expect it to be quite different in devices with swirl vanes. 

There are no models in the open literature for computing the effect of solids loading on swirl tube efficiency. The best approach for doing this in the first instance may be to fit the exponent a in a relationship of the Smolik type ... 

While there are several schools of thought regarding the exact mechanism behind the effect of solids loading on separation efficiency, the effect of loading on cyclone pressure drop is somewhat less contentious. 

Figure 9.1.5 shows experimental results for the effect of solids loading on pressure drop for the cyclone described in Fig. 9.1.1. 

Gil et al. compared a number of relations for predicting the effect of solids loading on cyclone efficiency and pressure drop. For the efficiency they found that the model of Muschelknautz (MM, see Chap. 6) predicted the effect exceptionally well. 

---