Flow Properties Of Slurries Research Articles

Experimental study of growth kinetics of CO2 hydrates and multiphase flow properties of slurries in high pressure flow systems.

The formation and accumulation of hydrates in high pressure oil and gas pipelines bring great risks to field development and deep-water transportation. In this paper, a high pressure flow loop equipped with visual window was used to study the growth process of hydrates in a pipe flow system and slurry flow characteristics. Deionized water, industrial white oil and CO2 were selected as the experiment medium. A series of experiments with different initial pressures (2.5–3 MPa), liquid loads (7–9 L), flow rates (25–35 kg min−1) and water cuts (60–100%) were designed and carried out. Specifically, hydrate formation and slurry flow characteristics in two different systems, pure water and oil–water emulsion system, were compared. Both of the systems experienced an induction stage, slurry flow stage and followed by a plugging stage. Although hydrate growth gradually ceased in the slurry flow stage, plugging still occurred due to the continuous agglomeration of hydrates. Visual observation showed that there were obvious stratification of the oil–water emulsion systems at the later time of slurry flow stage, which directly resulted in pipe blockage. The hydrate induction time of the flow systems gradually decreased with the increasing initial pressure, initial flow rate and water content. And the induction time tended to decrease first and then slowly increase with the increasing liquid loading. For emulsion systems, the apparent viscosity and friction coefficient of the hydrate slurry increased with the increasing water content, indicating that there were higher plugging risks compared to the pure water systems. Moreover, the results of sensitivity analysis showed that the water content was the main factor affecting the hydrate induction time, followed by the influence of liquid carrying capacity and flow rate, and the initial pressure had the least influence on the induction time. Conclusions obtained in this paper can provide some reference not only for the prevention and management of hydrates in pipelines, but also for the application of CO2 hydrate as a refrigerant.

Enhanced densification of thin tape cast Ceria-Gadolinium Oxide (CGO) layers by rheological optimization of slurries

Optimized CGO-based slurries are formulated and shaped into thin dense layers via a tape-casting process. The formulation is adjusted with respect to the rheological behaviour. The internal structure and flow properties of slurries are explored with the aim of identifying the required conditions to obtain thin dense CGO layers at reduced sintering temperatures (1200°C). We demonstrate a correlation between the rheological properties of the slurries, the sintering behaviour and the microstructure of the resulting tapes. Remarkably, a dense CGO layer less than 20µm thick is obtained with a non-congested slurry, having optimized ceramic loading and liquid-like behaviour.

A capillary viscometer for the study of the rheological properties of slurries

A capillary viscometer capable of measuring the flow properties of slurries with solids concentrations up to 33% is described. Shear rates between 30 s −1 and 950 s −1 can be produced in the apparatus using 3 capillaries of different diameters. Facilities are also provided to measure pressure losses caused by bends and fittings. Pressures can be measured to an accuracy of ±1% and flowrates to ±2%. The viscometer was tested with water and the results obtained were compared with published data. It was also tested with mixtures of water and milled barley and the results obtained were compared with those from a rotary bob and cup viscometer.

Flow Properties of Stable Slurries : (1st Report, Experiment)

On the flow properties of stable slurries of several polymer particles, experiments were carried out, using a Couette-type rotational viscometer and two capillary viscometers, in the range of concentration : 0∼45 (%) and rate of shear : 5∼7×103 (sec-1), changing the size of particles, the viscosity of suspending liquids and the temperature. The results obtained are as follows. (1) The flow properties of slurries are not independent of the kind of viscometer (rotational or capillary) and the apparent viscosity by the capillary viscometer is lower than one by the rotational viscometer, at the same rate of shear. (2) P.M.M.A.-slurry is a Newtonian fluid in the range of concentration from 0 to 20 (%). But, P.E.-and P.V.C.-slurries become non-Newtonian fluids at lower concentrations. (3) Oliver's constant of P.M.M.A.-slurry is 2.60 and its value agrees with the results of experiments by others.