Solid Particles In Liquid Research Articles

Liquid-solid particle slurry erosion of steels

The erosion behavior of candidate steel alloys for liquid-solid particle slurry service in coal conversion equipment was determined over a range of testing conditions. Higher solids loading and larger particles in the coal-kerosene slurries resulted in greater erosion. The greater the boundary lubrication of the carrier liquid, the lower the erosivity of the slurry. Low elevated temperatures can cause a decrease or an increase in the erosivity of the slurry, depending on the nature of the liquid carrier, the alloy tested and the test temperature. The mechanism of erosion was determined to be of a platelet formation type, similar to that observed in gas-solid particle stream erosion of ductile metals. However, the cold-worked zone caused by the striking particles is located at the surface in liquid-solid particle erosion while it is beneath the surface in gas-solid particle erosion. The relative erosion resistance of the carbon, low alloy, chromium bearing and austenitic steels tested could not be readily related to their composition, morphology or common mechanical properties. A possible relation to the strain-hardening behavior of the alloys was indicated.

Concentration-dependent behaviour of the shear viscosity of coal-fuel oil suspensions

A function correlating the relative viscosity of a suspension of solid particles in liquids to their concentration is derived here theoretically using only general thermodynamic ideas, with out any consideration of microscopic hydrodynamic models. This function (ηr = exp (1/2B*C2)) has a great advantage over the many different functions proposed in literature, for it depends on a single parameter,B*, and is therefore concise. To test the validity of this function, a least-squares regression analysis was undertaken of available data on the viscosity and concentration of suspensions of coal particles in fuel oil, which promise to be a useful alternative to fuel oil in the near future. The proposed function was found to accurately describe the concentration-dependent behaviour of the relative viscosity of these suspensions. Furthermore, an attempt was made to obtain information about the factors affecting the value ofB*, however the results were only qualitative because of, among other things, the inaccuracy of the viscosity measurements in such highly viscous fluids.

Erosion of steels in liquid slurries

The erosion of steels commonly used in piping and containment vessels in coal liquefaction plants was investigated. The jet impingement type of test where coal-particle-containing liquids are directed at flat specimens was used to determine the erosion rates and mechanism of coal slurry erosion. The effects of steel heat treatments, slurry impingement angles and other slurry erosion test conditions on erosion rates are discussed. Microscopic analysis was used to determine the mechanism of erosion. Comparisons between liquid-solid particle erosion and gas-solid particle erosion are presented.

Erosive wear of ductile metals by a particle-laden high velocity liquid jet

A liquid-solid particle jet impingement flow apparatus is described and experimental measurements are reported for the accelerated erosion of copper, aluminum and mild steel sheet metal by coal suspensions in kerosene and Al 2O 3 and SiC suspensions in water. Slurry velocities of up to 130 ft s −1 (40 m s −1) and impingement angles of 15°–90° were investigated. The maximum particle concentration used was 40 wt.%. For high velocity the results of this work show two erosion maxima; these are found at impingement angles of 90° and 40°. However, in corresponding gas-solid particle investigations maximum erosion occurs at approximately 20°. In this work both particle concentration and composition were varied. A polynomial regression technique was used to calculate empirical and semitheoretical correlation constants.

A model for the thixotropy of suspensions

AbstractA model for the rheological behavior of thixotropic systems is presented. The model is intended for systems exhibiting no elastic or anisotropic effects. It is shown how the constants of the model can be determined by a systematic program of experimentation. It is also shown how the model can be tested and amended, if necessary, by the same program of experiments. The model is advanced for suspensions of rigid, solid particles in liquids; it is not expected to be valid for materials of polymeric constitution or for suspensions of elastic, deformable particles in liquids.

Suspension of solids by bubble agitation

AbstractUsing fundamental aspects of the fluid mechanics of a single particle, a relation for the velocity of liquid necessary to suspend solid particles in a shallow depth column is derived. This liquid velocity is developed by the movement of the gas bubbles inside the column with the potential energy dissipated by the bubble during its ascent taken as the gain in the kinetic energy of the liquid. This energy brings about sufficient liquid motion to suspend the particles. The corresponding superficial gas velocity to suspend all the particles present in the column is theoretically estimated and compared to experimental values of superficial gas velocities obtained for various solids concentrations. A set pattern of deviation is observed, and empirical correlations are suggested for predicting the superficial gas velocity to suspend a given amount of solid particles in liquid.

A variable‐density model of the pipeline flow of suspensions

AbstractThe turbulent flow of suspensions of fine solid particles in liquids is analyzed by assuming that the suspensions behave essentially as variable‐density single phase fluids. Friction factors are found to depend upon the distribution of solid particles within the conduit as well as the Reynolds number of the flow. Comparison of the model with experimental measurements indicates that as long as turbulent suspension of solid particles occurs, the model is a useful alternative to the empirical Durand equation for pipeline design.

Studies on mixing. X. Suspending solid particles in liquids by means of mechanical agitation

Studies on mixing. X. Suspending solid particles in liquids by means of mechanical agitation

Suspending of solid particles in liquid by agitators

Abstract An investigation of the required stirrer speed and stirrer dimensions for the suspending of solid particles in a low viscosity liquid has been carried out. The results are given in dimensionless form. By means of these empirical correlations the design for this operation can be carried out in many simple cases. For more complicated systems it will probably be better to carry out trial experiments. Rules for scaling are discussed. As a criterion for complete suspension the condition is chosen that no solid matter rests on the bottom of the stirred vessel ; the homogeneity of the suspension throughout the whole vessel is not especially examined. The results are compared with data from literature. Theoretical consideration for the mechanism underlying the lifting of the particles from the bottom are not given, but research into this mechanism will be continued.

Structure in Surfaces of Liquids

MR. HATSCHEK, in his interesting article in NATURE of June 11, p. 857, has shown that colloidal solutions and even the simplest suspensions of solid particles in liquids exhibit a property which is absent from all true liquids; namely, residual rigidity, or at least a coefficient of viscosity that depends upon tho rate of shear. He has advanced no explanation of this remarkable result, which would, however, appear to be just one manifestation of a general property of all surfaces involving liquids.

Subsidence of fine solid particles in liquids

Subsidence of fine solid particles in liquids