Effect of slurry concentration

Table 7.3 Effect of slurry concentration and C02 flow rates, Orifice diameter on conversion and cavitation yield [46]...

Filtration characteristics Volume of filtrate versus time, filtrate rate, volume of filter cake, cake porosity, clarity of filtrate, clogging of filter media, effect of slurry concentration on filtrate rate and filtrate clarity, effect of slurry viscosity on filtrate rate and media clogging, etc. 

Figure 2. Effect of slurry concentration on decomposition during dehydration...

Figure 13.8 Batch settling of slurries. Effect of slurry concentration.

The effect of slurry concentration on the settling characteristics of a slurry at elevated temperatures is illustrated in Fig. 4-10. The bulk of this slurry (>80w/o) was made up of spherical agglomerates 10 to 15 microns in size. The data indicate that the slurry settling rate is an exponential function of the concentration and has the form... 

The need to separate solid and liquid phases is probably the most common phase separation requirement in the process industries, and a variety of techniques is used (Figure 10.9). Separation is effected by either the difference in density between the liquid and solids, using either gravity or centrifugal force, or, for filtration, depends on the particle size and shape. The most suitable technique to use will depend on the solids concentration and feed rate, as well as the size and nature of the solid particles. The range of application of various techniques and equipment, as a function of slurry concentration and particle size, is shown in Figure 10.10. 

Figure 7. Effects of millimolar concentrations of 3-mercaptopropionate on acetate accumulation in sediment slurries. Symbols no 3-MPA, Q 1 mM 3-MPA, 10 mM 3-MPA, A 20mM3-MPA, . ...

Reaction Order. Rate Constants and Activation Energy (Slurry-Reactor). Hydrogentation of a-methylstyrene was selected for a test reaction. This reaction has been studied extensively by a number of investigators (6, 11. 14, 15, 17). Previous studies used Pd/A 203 or Pd-black catalysts in a-methylstyrene-cumene mixtures. We wanted to verify the kinetics of this reaction in various solvents of different physical properties (cyclohexane, hexane (u.v.), hexane (A.C.S), toluene, 2-propanol) and examine the effect of Pd concentration on the rate. The above solvents were to be utilized in trickle-bed reaction studies also to provide a range of liquid physical properties. 

Effect of Slurry Velocity on Solid Concentration Profiles. 

Figure 5.3. Effect of the concentration of nitric acid on the peak intensities of severai metals in sediment slurry using Ru as permanent modifier. (Reproduced with permission of Elsevier, Ref [10].)...

The effect of slurry abrasive size on polish rate is not very clear. Different results have been reported for oxide polishing showing contradicting conclusions. Results obtained by Jairath et al. [S] suggested that the oxide polish rate increases with both abrasive particle size and concentration. However, other reports found that glass polish rate is constant with abrasive size [6], [7] or even decreases with abrasive size [8]. 

Figure 4.14 shows the effect of coal concentration in the slurry on the syngas composition. It is shown that increasing coal concentration is helpful for a higher... 

Figure 4.14. Effect of coal concentration in slurry on syngas composition.

Fig. 2 Effects of solid concentration on the viscosity of a particular coal slurry. Beyond a certain limiting concentration, the viscosity rapidly increases to extremely high values. (From Ref. ". )...

Figure 3. Effect of H202 concentration on the electrochemical corrosion potential drop of At in the slurry at pH 2.

The effects of polymer concentration, shear rate, and temperature were also investigated. As the polymer concentration increases (power law exponent n decreases, that is, the viscosity of the carrier fluid or suspending liquid increases), the relative viscosity of the pseudoplastic slurry decreases. It is important to know that the more viscous the fluid (lower n value), its relative viscosity will deviate further from the Newtonian predictions. Relative viscosity decreases as the shear rate increases. Again, the effect is more pronounced at higher solid concentration than at low solid concentration. Temperature also has a dramatic effect on the relative viscosity of slurries. This effect is partly due to the reduction in carrier fluid viscosity because of thermal effects. The relative viscosity increases as the temperature increases. Overall, Shah s experimental results agree more closely with Keck s than with any other reported study. 

Marlow and Rowell (37) working with coal/water slurries and using the CVP technique have shown that, at the frequencies of their measurements (200 kHz), the effect of particle concentration can be adequately described by introducing a factor (1 — g ) into their equivalent of Eq. (1) where again, g was very close to unity. In their review article Marlow et al. (6) discuss the way the cell model of Levine and coworkers (38, 39) is introduced into the CVP theory and show that, for thin double layers, the result is that the hydrodynamic and electrostatic interactions essentially cancel one another and one is left with only the factor (1—d)) to take account of the backflow of liquid caused by the particle motion. 

Equations 6.5 to 6.7 primarily represent the test results of the study published previously but, unlike some other models in the literature, they are based on a physical model of hydrocyclone operation and particle behaviour and, as such, have a much better chance of success when applied to conditions outside those tested. Another research project at Bradford is directed at the effects of solids concentrations greater than 10% when many practical slurries show non-Newtonian behaviour. 

Sellgren, A. and L. Vappling. 1986. Effects of highly concentrated slurries on the performance of centrifugal pumps. Proceedings of the International Symposium on Sluny Plows, FED Vol 38, ASME, USA, pp. 143-148. 

The effect of solids concentration on deposition Froude number in Figure 4 was also reported by Thomas [7]. The increase in deposition velocity with solids concentration contrasts with that which be shown later to occur for finer particles with broad size distributions. As the slurry concentration increases the slurry viscosity begins to increase rapidly at concentrations above 30% by volume. This causes the Reynolds number of the mixture flow to decrease at a given velocity, which according to Gillies and Shook [6], tends to increase the contact load. 

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