Gas Liquid Solid Three-phase Research Articles

Hydrodynamics Characteristics of High Speed Multi-Phase Flow in AWJ Nozzles. 2nd Report, Measurement of Exit Phase-Velocities and Velocity Change in Nozzles.

The experimental results on the abrasive water jet (AWJ) are described in this paper. AWJ is the high-speed water jet containing solid particles and is used for cutting of various industrial materials. In order to obtain the velocities of solid, gas and liquid phases at the mixing nozzle exit, the momentum of jet was measured. Phase velocity distribution in the axial direction of jet was also estimated based on the measured pressure distribution in the AWJ nozzle with the aid of the continuous and the momentum equations. The result shows that the decrease of the liquid phase velocity in the mixing nozzle is small in the case of the gas liquid two phase flow, and the velocity of liquid phase is remarkably reduced on the contrary in the gas liquid-solid three-phase flow. In the latter case, the total momentum of jet is reduced comparing with two phase flow. It is also found that the mean velocity of solid particles at the mixing nozzle exit is about 30% of the velocity of liquid phase.

Minimum fluidization velocities for gas—liquid—solid three-phase systems

Cocurrent upward gas—liquid fluidization of coarse solids is actuated primarily by the motion of the liquid at relatively low gas velocities and by the momentum of the gas at zero or low liquid velocities. Our gas-perturbed liquid model, which has previously been shown to give good predictions of the minimum liquid fluidization velocity, U lmf, at a fixed low gas velocity, is shown here also to give reasonable agreement with U lmf measurements for inverse three-phase fluidization at a given upward gas velocity, using the coefficient in the gas hold-up equation of Yang et al. [X.L. Yang, G. Wild, J.P. Euzen, Int. Chem. Eng. 33 (1993) 72] as an adjustable parameter. It is further shown that a liquid-buoyed solids/liquid-perturbed gas model can predict with moderate success the minimum gas fluidization velocity, U gmf, for three-phase cocurrent upward fluidization of coarse solids at zero or low liquid velocities.

THEORETICAL ANALYSIS OF FLOW CHARACTERISTICS OF MULTIPHASE MIXTURES IN A VERTICAL PIPE

This paper is concerned with the theoretical analysis to obtain the flow characteristics of multiphase mixtures in a vertically fixed air-lifting pipe. In this present investigation, the case is treated where a transition process from a solid–liquid two-phase mixture flow to a solid–gas–liquid three-phase mixture by injecting gas-phase into the upriser through a gas injector is present. The system of equations governing the liquid–solid two-phase mixture flow consists of two mass conservation equations, two momentum conservation equations and a requirement for two phase volumetric fractions. Again, the gas–liquid–solid three-phase flow field after the position of gas injection is solved by three mass conservation equations, three momentum equations, a gas equation of state and a requirement for the individual phase volumetric fractions. The transitions of the flow pattern of gas phase from bubbly to slug flows and from slug to churn flows are taken into account in the system of equations governing the three-phase flows. In order to verify the validity of the system of governing equations accounting for the flow patterns transitions of gas-phase, the flow characteristics calculated on the basis of the present theoretical model have been compared with experimental data measured by the other investigators. As a result, we have found that the present theoretical model built up in this study gives a good fit to the experimental data obtained by several investigators. Furthermore, we have demonstrated that the present model is capable of predicting the maximum solid/liquid volumetric flux.

揚鉱管内を上昇する混相流体の流動特性の理論的解析

The purpose of the present investigation is to theoretically analyze the flow characteristics of the air-lift pump for the case where a transitional process from the solid-liquid two-phase mixture flow to the solid-gasliquid three-phase mixture flow by injecting gas-phase into the upriser through a gas-injector is present. The system of equations governing the liquid-solid two-phase mixture flow consists of two mass conservation equations, two momentum conservation equations and an equation for two-phase volume fractions. Again, the gasliquid-solid three-phase flow field after the position of gas injection is solved by three mass conservation equations, three momentum equations, a gas equation of state and an equation for the individual phase volume fractions. The transitions of the flow pattern of gas phase from the bubbly flow to the slug flow and from the slug flow to the churn flow are taken into account in the system of governing equations of three-phase flow. In order to verify the validity of the system of governing equations accounting for the transition of the flow patterns, the flow characteristics calculated on the basis of the present theoretical model have been compared with experimental data by several other investigators. As a result, we have found that the present theoretical model built up in this study gives good fit to the experimental data obtained by several investigators.

深海底鉱物揚鉱用エアリフトポンプの流動特性に及ぼす諸因子の影響

The purposes of this study are to obtain designing data and safety operational conditions for air-lift pumps of lifting marine mineral resources such as maganese nodules from deep-sea floor of about 5, 000m to a mining ship. A large amount of air is absorbed into water, because the air is injected in a deeper position of conveying pipe at high pressure; therefore, the numerical procedure based on the drift flux model for steady gas-liquidsolid three-phase flow takes account of the mass transfer between gas-phase and liquid-phase.In this paper, we discuss effects of several factors, such as coefficients of the constitutive equations; air absorption into water; inner diameter, wall roughness and length of each section of conveying pipe; pressure drop coefficients; physical properties and delivered concentration of solid particles on flow characteristics. The results of this numerical simulation serve a basic performance of a large scale air-lift pump.

エアリフト方式による深海底資源の揚鉱システムの基礎的研究（第３報）揚鉱管途中の空気注入による２相流から３相流への遷移を含めた非平衡な流れ場の理論解析

This paper treats theoretical analyses to predict the steady flow characteristics of multiphase mixture in an air lifting pipe. When slurries containing solid particles such as manganese nodules are lifted from the deep-sea bed to the sea surface by an air lift pump, gas phase is injected halfway into a lifting pipe with a very large length ranging from the sea floor of about 5, 000 m in depth to the sea surface. Therefore, liquid-solid two-phase flow is formed in a deeper part of the lifting pipe, but changes into gasliquid-solid three-phase flow just after the position of the gas injection.Here, the case is treated where slurries are the solid particles-sea water two-phase mixture before the position of the gas injection and the air-solid particles-sea water three-phase mixture after that. The equations governing the liquid-solid two-phase slurry flow consist of two continuity equations, two momentum equations and an equation for two-phase volume fractions. However, the gas-liquid-solid threephase flow field after the position of the gas injection is governed by three continuity equations, three momentum equations, a gas equation of state and an equation for three-phase volume fractions. In the two-phase region, the individual volume fractions and lifting velocities of the solid and liquid phases remain self-evidently unchangeable. The abrupt drop of the volume fractions as well as the abrupt jump of the lifting velocities occur at the transitional position from the two-phase to the three-phase flow. In the three-phase region, the three momentum equations for the individual phases are solved as the perturbation from the solutions to the equilibrium/homogeneous flow and then the remaining five flow properties are determined.Some numerical experiments are performed using a set of five equations in the two-phase region and a set of eight equations in the three-phase region for determining the flow properties. By comparing the non-equilibrium solutions with the numerical results of the case where the three-phase flow is assumed to be in velocity equilibrium, it is numerically shown that the equilibrium solution gives a threshold of the highest possible solid-phase mass flux on condition that bath the gas-phase and liquid-phase mass fluxes are kept constant. With increasing solid particle size the non-equilibrium solution obtained directly as the perturbation from the equilibrium one is found to have a tendency to deviate from the original equilibrium one. Such important problems are described in detail.