The influence of precipitated asphaltenes on sedimentation of particles in coal liquids

Abstract

Antisolvent addition to coal liquids causes the precipitation of asphaltenes on mineral particles and increases their sedimentation rate. This paper develops a mathematical model of the sedimentation rate of a single particle or agglomerate of particles. It was found that if the difference in density between the solid and the precipitate is more than twice the difference in density between the precipite and the liquid, the sedimentation rate would decrease initially upon precipitation. A simple experiment was performed to confirm the prediction. Further it was found that the agglomeration of particles had a stronger effect upon the sedimentation than the changes in particle size, ecently, coal liquefaction processes have received

Advantages of estimating settling rates of fine particles with nomographs

“…The models introduced to predict the settling rates of sedimentation in multiparticle systems, vs F, such as those of Hawksley (in [8], Robinson [in 48], Maude & Withmore [44], Wallis [57] or EinsteinSmoluchowski [32], are corrections of the raw expression for vp 0 . For example, these models replace the properties of the liquid with the overall propertiesviscosity [21,41,43,50,52,56,61] and density [14,21,52,56] -of the suspension considered as a microfluid . Many of these equations are analogous to those introduced to adjust the experimental data of sedimentation velocities, v so , such as those of Richardson and Zaki [48], Steinour [23,48], Michaels and Bolger [40], Vesilind [49,55], Dick and Young [18,47,49,58], Krone [58], Yoshioka [60], Garside and AlDibouni [26], Oliver [20], and those developed by the authors [12,13] .…”

Indirect measurement of inclined sedimentation for ash in coal liquids at high temperature and pressure by x-ray photography

“…The motivation for developing the experimental technique discussed here was the problem of observing the sedimentation of mineral particles in coal-derived liquids at high temperature and pressure in an inclined settler. Often antisolvents are added to coal-derived liquids to precipitate asphaltic or preasphaltic fractions, which promote the agglomeration of the mineral matter (Verhoff et al, 1978). In addition to observing the initial settling rate it is critical to observe the buildup of the compression zone in such systems.…”