Suspensions liquid, viscosity

Roy et al. (R3) define the critical solids holdup as the maximum quantity of solids that can be held in suspension in an agitated liquid. They present measurements of this factor for various values of gas velocity, gas distribution, solid-particle size, liquid surface tension, liquid viscosity, and a solid-liquid wettability parameter, and they propose the following two correlations in terms of dimensionless groups containing these parameters ... 

Davies and Dollimore [71] conclude that hindrance is directly related to surface density of charge on the particle, particle density and liquid viscosity. It is inversely related to the difference in viscosity between the suspension and the bulk liquid and the cation-stability constant. 

Unlike a solid-in-liquid suspension, the viscosity of an emulsion may depend upon the viscosity of the dispersed phase. This dependence is especially true when internal circulation occurs within the dispersed droplets. The presence of internal circulation reduces the distortion of the flow field around the droplets (26), and consequently the overall viscosity of an emulsion is lower than that of a suspension at the same volume fraction. With the... 

Separation involving sedimentation is dependent upon settling velocity, which requires a difference in density between solid particles and the suspending liquid. Gravitational sedimentation operations are divided into clarification and thickening. Clarification involves dilute suspensions and frequently has the objective of liquid recovery. Thickening refers to solid recovery by forming more concentrated slurries. Particle size, liquid and particle densities, and liquid viscosity are important factors in sedimentation processes. 

Solid-liquid mixing involves the suspension, distribution, and the drawing down of solids by agitation. In addition to vessel geometiy, impeller variables include type, diameter, number, speed, and location. Process results include the desired level (quality) of suspension, such as just off-the-bottom, complete uniformity, or any intermediate condition. The slurry properties, density difference (solid/liquid), viscosity, and solids concentration all determine how difficult the task may be. As alternatives to stirred vessels, jets (see Section 9.10) can be used for light-duty suspension. Literature references deal mainly with settling solids as opposed to floating solids. We will try to address both conditions. 

The product of the specific filter resistance a and the liquid viscosity tj lies in the ranges between at] =10 mPa s for filterable suspensions and arj =10 mPa s for insufficiently filterable suspensions. 

SBAS reinforcing fibers were fabricated via the ACI s viscous suspension spinning process (VSSP) °. In this process, cellulose is digested in a sodium hydroxide aqueous solution in the form of a viscous liquid (viscose) that is mixed with the SBAS powder dispersed in a water slurry (Figure 2a). It should be noted that the lower amount of HTE, compared to the matrix composition, was used in the mixture for fibers to increase their sintering temperature and prevent strong fiber-to-matrix bonding. 

The critical speed for gas induction is solely decided by the ability of the rotor to generate a suction higher than the sum of static head and other pressure losses. The rotor design obviously plays an important role. Even when a second impeller is employed for gas dispersion/solid suspension, its action is limited to the role assigned to it in a region substantially away from the gas-inducing device. Therefore, the presence of the second impeller should not have any effect on the critical speed for gas induction in a multiple-impeller system. This obvious fact was experimentally proved by Saravanan and Joshi (1995). Consequently, Equations 9.23 or 9.28, which yield similar predictions, can be used to predict The effect of liquid viscosity can be accounted through Equation 9.24. 

Inorganic particles can be selectively wetted by the liquid phase if the particles and the liquid undergo favorable energetic interactions, such as polar-polar interactions, hydrogen bonding, or acid-base interactions. Thermodynamic equilibrium and the highest attainable entropy are easily reached in the cases of suspensions in liquids of low molecular weight due to very low liquid viscosity and fast molecular diffusion. 

Each flowing phase is viewed as a continuum and the catalyst particles surface is completely covered by a liquid film and the gas flows in the remaining interstitial void. The properties of the fluid suspension (density, viscosity, holdup) are equal to those of the embracing liquid (influent fine volume fraction <0.1%). Only the influent liquid was considered as a source for (single-sized)... 

Whilst isokinetic sampling is usually critical in dust-laden gas ° sampling it does not have to be observed in most applications of liquid suspension sampling because of the high liquid viscosities. An inertia parameter (Stokes number) is usually used to assess the necessity of isokinetic samphng Parker suggested the range of... 

The presence of higher concentrations of particles in the flow modifies the velocity profiles in the cyclone and increases capacity. Some authors take the view that the effect is the same as of higher liquid viscosity and density, and recommend the use of the apparent suspension viscosity of the feed slurry and density of the slurry rather than that of the suspending liquid. While this approach oversimplifies the real process in the cyclone, the increase in cyclone capacity with concentration is small anyway and the errors may be acceptable (in practice, clean liquid data are often used regardless of concentration and the capacity may then be adjusted in plant by throttling or by other means). 

The effect of PVB additions on the dispersion behavior can be seen from Figure 4.9 to be dependent on the suspension liquid composition. In MEOH suspension, though addition of PVB reduces the viscosity of the suspension, the system is shear-thinning indicating that the suspensions remain flocculated in poorer solvents for the added... 

If the measured viscosity rj is constant with respect to shear rate, then the liquid is said to be Newtonian as described above. However, as is usually the case for structured liquids such as polymer solutions and suspensions, the viscosity decreases with increasing shear rate such liquids are described as shear thinning. Occasionally, situations arise where the opposite is true, and the viscosity increases with increasing shear rate these are called shear-thickening liquids, see chapter 15. 

In this equation [ig is not the liquid viscosity but the liquid/ solid suspension viscosity given by [38]... 

There are four types of turbine impellers, which are characterized by the flow patterns and level of shear they create axial flow, radial flow, hydrofoil, and high-shear impellers. They have the widest use in low and medium viscosity liquid applications, solids suspension, liquid-liquid emulsification, and gas dispersion. Turbine impellers can have blades varying from 2 to 12 in number. Two blades are normally unstable mechanically, while it is difficult to install more than six blades on a hub. Axial flow impellers generally have three or four blades, and radial flow impellers are designed with six blades. 

The phenomenon of the viscosity of a polar liquid (such as glycerin) increasing slightly when an external electric field is applied (ER effect) was observed as early as the end of the nineteenth century [51]. In 1947, Winslow applied an electric field on a suspension of limestone particles in mineral oil to refine the mineral oil. He then discovered that the viscosity of the suspension solution increased drastically [52, 53]. The electro-rheological effect (ER effect) of a particle-suspension liquid is also called the Winslow effect. Winslow further found significant effects on silica and starch and thus thought that the ER effect originates from the moisture contained on the particles. 

Hindered Settling When particle concentration increases, particle settling velocities decrease oecause of hydrodynamic interaction between particles and the upward motion of displaced liquid. The suspension viscosity increases. Hindered setthng is normally encountered in sedimentation and transport of concentrated slurries. Below 0.1 percent volumetric particle concentration, there is less than a 1 percent reduction in settling velocity. Several expressions have been given to estimate the effect of particle volume fraction on settling velocity. Maude and Whitmore Br. J. Appl. Fhys., 9, 477—482 [1958]) give, for uniformly sized spheres,... 

PHASE CONTACTING AND LIQUID-SOLID PROCESSING AGITATION OF LOW-VISCOSITY PARTICLE SUSPENSIONS... 

Propeller mixers are used for mixing liquids with viscosities up to 2,000 cp. They are suitable for the formation of low-viscosity emulsions, for dissolving applications and for liquid-phase chemical reactions. For suspensions, the upper limit of particle size is 0.1 to 0.5 mm, with a maximum dry residue of 10%. 

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