Solid Phase Particles Research Articles

A novel fractal model for effective thermal conductivity in granular porous media

Quantitative prediction of effective thermal conductivity in porous media is very important in various industrial applications and scientific researches. As the topology and geometry characteristics of pore-solid space is extremely complicated, an accurately theoretical calculation in porous media is still a great challenge. In this study, a novel theoretical model of effective thermal conductivity is derived in granular porous media originated from the Laplace's Equation with a new boundary condition. The proposed model considers the size of solid particles following the fractal distribution characteristics, which is expressed as a function of porosity, fractal dimension of solid particle, maximum particle radius, representative length, and thermal conductivity of both solid particle and pore phase. The predictions of proposed model show a good agreement with the existing models and various published experimental data, which validates its accuracy and reliability. The effect of different geometrical parameters for proposed model is analyzed and discussed. This novel proposed model of effective thermal conductivity may reveal a better insight for thermophysical mechanisms in granular porous media than conventional models.

A novel theoretical model of gas–solid two-phase flow mixed dielectric discharge

A theoretical physical model of gas–solid two-phase flow mixed dielectric discharge in a uniform field based on Townsend's discharge theory is presented. This model extends the classical Townsend's theory to be applicable to the quantitative analysis of dielectric discharge questions related to gas–solid two-phase flow environments, reveals the influence mechanism of flowing gases and solid-phase particles on discharge, and provides a theoretical basis for expanding the application of discharge plasma technology in various fields. In the model, based on the basic physical process of gas discharge and our previous studies, the effects of the attraction and obstructive factors of solid-phase particles on the number density of electrons or ions and the local space electric field in the inception and development of gas discharge were taken into account. On this basis, the analytical expression of the breakdown voltage in a gas–solid two-phase flow mixed dielectric is obtained, Paschen's law of gas breakdown is modified, and Townsend's breakdown criterion for gas–solid two-phase flow situation is proposed. It is shown that the breakdown voltage of the gas–solid two-phase flow mixed dielectric decreases with increasing gas flow velocity. The gas flow velocity is the main factor affecting the variation trend of the breakdown voltage. The concentration and size of solid-phase particles determine the values of breakdown voltage. The breakdown voltage of the smaller size and higher concentration of solid-phase particles is greater, which has a stronger suppression effect on the discharge.

A novel approach for nature gas hydrate separation: Downhole spiral-cyclone coupled hydraulic in-situ separation

The weakly cemented mixture slurry which is formed by the natural gas hydrate (NGH) solid-state fluidization mining method that is composed of natural gas hydrate, sediment and water. The downhole cyclone of NGH needs to deal with such problems as high viscosity, narrow radial working space, and difficult to adjust the split ratio. Directly using the conventional solid-liquid cyclone structure for downhole sand removal cannot obtain good separation performance. And the conventional separator does not have a tubular structure suitable for solid fluidization exploitation of NGH. Therefore, in order to solve the problem of weak cementation between NGH and sediment due to large sand production during NGH exploitation, this study proposes a new method to separate weakly cemented natural gas hydrate based on the principle of spiral-cyclone coupling. And the model of spiral-cyclone separator was established. This method can break weakly cemented solid-phase particles in the slurry, and the effective separation and removal of ultra-fine sediment with cross-scale and micron size. The research also designs and optimizes the separation device for NGH sand removal. According to numerical simulation and theoretical analysis, the separation efficiency is greater than 60% when the particle size is larger than 5 µm and the inlet velocity is between 2 m/s and 10 m/s. The research results show that the proposed spiral-cyclone separation method has the characteristics of high separation efficiency, strong sand removal, and can break the cementation bond between the sediment and natural gas hydrate, which is a high-efficiency solid-liquid separation technology.

Study on the Erosion of Choke Valves in High-Pressure, High-Temperature Gas Wells

During the process of gas production in high-pressure, high-temperature (HPHT) gas wells, the choke valve, as the most vital component of the surface control equipment, plays a significant role in regulating the output and reducing the fluid pressure to ensure the safety of surface gathering and transportation equipment. High-pressure, high-velocity fluid flow and solid-phase particles cause deterioration of the choke valve. With the enhancement of intelligent and digital oilfields, conventional choke valves have been progressively replaced by electric choke valves. Due to the complex structure of the throttle valve, the flow path and the velocity state of the fluid in the throttle valve, and the distribution law of the erosion fraction are quite distinctive from those in the ordinary throttle valve, meriting further research. In this paper, a simulation of computational fluid dynamics (CFD) was conducted to determine the effects of the pressure distribution, fluid state, divergent particle sizes, and sand volume on the erosion rate of the choke valve. Under various valve openings, the fluid state and the location of high-risk points can be ascertained. The large particle size (diameter greater than 6 mm) of sand and gravel is convenient for causing concentrated erosion in the position of the valve hole, which induces the channel diameter to expand. Fine silt sand (diameter from 0.1 mm to 1 mm) gives rise to relatively uniform abrasion to the choke’s current-facing surface. This study can optimize the layout of the choke valve and reduce the cost and number of switching wells, thereby decreasing the frequency of maintenance and the pressure fluctuation’s effect on the formation.

Unified gas-kinetic wave-particle method for three-dimensional simulation of gas-particle fluidized bed

The gas–solid particle two-phase flow in a fluidized bed shows complex physics. The multi-scale algorithm composed of the coupled gas-kinetic scheme (GKS) for the gas phase and unified gas-kinetic wave-particle method (UGKWP) for the solid particle phase is developed for three-dimensional fluidized bed study. For the solid-particle phase, different from the widely-used Eulerian and Lagrangian approaches, the UGKWP unifies the wave (dense particle region) and discrete particle (dilute particle region) formulation seamlessly according to a continuous variation of particle cell’s Knudsen number (Kn). The GKS-UGKWP for the coupled gas-particle evolution system can automatically become an Eulerian–Eulerian (EE) method in the high particle collision regime and Eulerian–Lagrangian (EL) formulation in the collisionless particle regime. In the transition regime, the UGKWP can achieve a smooth transition between the Eulerian and Lagrangian limiting formulation. More importantly, the weights of mass distributions from analytical wave and discrete particle are related to the local Kn by (1−exp(−1/Kn)) for wave and exp(−1/Kn) for discrete particle. The UGKWP provides an optimal modeling in capturing the particle phase in difference regimes with the full consideration of physical accuracy and numerical efficiency. In the numerical simulation, the UGKWP does not need any prior division of dilute/dense regions, which makes it suitable for the fluidized bed problem, where the dilute/transition/dense regions instantaneously coexist and are dynamically interconvertible. In this paper, based on the GKS-UGKWP formulation two lab-scale fluidization cases, i.e., one turbulent fluidized bed and one circulating fluidized bed, are simulated in 3D and the simulation results are compared with the experimental measurements. The typical heterogeneous flow features of the fluidized bed are well captured and the statistics are in good agreement with experiment data.

Adsorption and flocculation properties of modified polyacrylamide in water dispersions of kaolin

A cationic flocculant with an amide-type polymer matrix was synthesized by modifying polyacrylamide according to the Mannich reaction. The use of a modified polymer leads to an increase in the adsorption of the polymer on solid phase particles in an aqueous dispersion of kaolin, an increase in the rate of kaolin sedimentation by a factor of 1.2–1.4, and makes it possible to expand the concentration range of dispersion destabilization compared to polyacrylamide.

Acetylene black interlayer regulated sulfur deposition for lithium-sulfur batteries with high utilization and long-term life

Lithium-sulfur (Li-S) batteries are considered to be competitive next-generation energy storage systems. However, practical applications are limited due to the shuttle of lithium polysulfides (LiPSs) and the poor electronic conductivity of the sulfur cathode, especially at high-rate currents. Here, we applied commercialized Acetylene black (AB) as separator coating in Li-S batteries. The stacking of AB nanospheres forms a void space that can physically adsorb polysulfides, store electrolytes, and promote lithium-ion diffusion; Simultaneously, it forms an excellent electronic conduction network that significantly improves the utilization of higher-order LiPSs. The thickness and composition of the coating can regulate the nucleation of crystalline S and Li2S to promote the uniform deposition of solid-phase particles. AB-150 releases an initial capacity of 961.3 mAh g−1 and still maintains at 825 mAh g−1 after 100 cycles with a capacity retention rate of 85.8% at 0.2C. Even remains at 371.2 mAh g−1 after 1000 cycles at 1C with a weak capacity decay rate of 0.06% per cycle. These understandings can also be extended to the design of polar/catalytic interlayer materials driving the large-scale application of Li-S batteries.

Numerical Simulation of Solid-Liquid Two-Phase Flow in Non-Clog Pump

This paper mainly based on the CFD numerical simulation method to analyze the solid-liquid two-phase flow of the vortex pump. Three kinds of solid-phase volume concentration and three solid-phase particle diameters were given respectively to carry out the numerical simulation of solid-liquid two-phase flow in the internal flow field of the pump. The distribution of solid particles in the impeller and the lateral cavity were analyzed to study the influence of different solid-phase particle diameters and solid-phase particle concentrations on the pump performance. The results showed that there was no obvious concentration distribution at the junction area between blades and hub. The solid phase concentration on the back is lower than that on the working face. Due to the characteristics of circulating flow in the vortex pump, some particles enter the lateral cavity from the blade working face, and some particles enter the blade back face from the lateral cavity under the action of low pressure on the back and circulating flow. Solid particles are mainly distributed in the center of the cavity and are circularly distributed. The overall fluctuation of the solid phase slip velocity on the working face is not large, while the magnitude of the solid phase slip velocity on the back is relatively disordered.

Numerical Simulation on Erosion Wear Law of Pressure-Controlled Injection Tool in Solid Fluidization Exploitation of the Deep-Water Natural Gas Hydrate

The pressure-controlled injection tool (PCIT) is the key equipment in the process of high-pressure water jet fragmentation in the solid fluidization exploitation of deep-sea natural gas hydrate (NGH). The internal flow field erosion wear numerical simulation model of PCIT is established through computational fluid dynamics software to study the influence law and main factors of the drilling fluid erosion wear of PCIT. The influence laws of different drilling fluid physical parameters and different structural parameters on PCIT erosion wear were analyzed based on the Euler–Lagrangian algorithm bidirectional coupled discrete phase model (DPM) and the solid–liquid two-phase flow model. The results show that the easily eroded areas are the cone of the sliding core, the plug transition section, the plug surface, and the axial flow passage. The sliding core inlet angle and solid particle size are the main factors affecting the PCIT erosion rate. When the inlet angle of the sliding core is 30°, the diameter of solid-phase particles in drilling fluid is less than 0.3 mm, and the erosion degree of the PCIT could be effectively reduced. The research results can provide guidance for the design and application of the PCIT and advance the early realization of the commercial exploitation of hydrate.

Numerical Simulation of Slope–Gully–Stream Sediment Transport Process with Water and Gravity Erosion

Soil erosion has become a global problem with serious consequences. It is the source of sediment in rivers, and the subsequent sediment transport is important. Water erosion and gravity erosion, as common forms of soil erosion, have different subsequent sediment transport processes. Numerical simulations can reflect these processes well under different sediment yield types. This study applied the computational fluid dynamics and discrete element method (CFD-DEM) to examine the sediment transport following water erosion and gravity erosion. During the sediment transport process, the solid-phase particles in the gravity erosion case move at a greater speed during the initial stage. In the case of water erosion, a decrease in particle velocity on the slope occurs due to the accumulation of particles. The streamwise velocity distribution of the liquid phase conforms to the logarithmic distribution before the sediment transport process starts. Influenced by the solid-phase particles, the flow velocity near the bottom decreases significantly. The sediment transport rate peak in gravity erosion cases is greater than that in water erosion cases. Furthermore, in water erosion cases, when the slope is steep, there is no peak in the sections located at the inlet and outlet of a gully. The sediment transport rate in river sections shows a step form in the declining process.

Complex measurement of parameters of iron ore magnetic separation based on ultrasonic methods

Purpose. To develop a method for complex ultrasonic measurement of such parameters of the iron ore slurry flow passing through the working chamber of the magnetic separator as efficiency, concentration and grade size distribution of solid-phase particles. Methodology. The research uses methods of modelling processes of ultrasonic wave propagation in the iron ore slurry. Ultrasonic wave absorption and scattering in water with solid particles and air bubbles are considered. To characterize absorption and scattering of acoustic oscillations by oscillating gas bubbles, concepts of effective cross-sections of attenuation, absorption and scattering are introduced. Findings. The dependence of the phase velocity of asymmetric Lamb waves on the wall thickness of the magnetic separator was obtained. As a result of computer simulation of the process of ultrasonic waves propagation, its time and frequency characteristics were obtained. Based on the data obtained using ultrasonic measurements, the coefficients of the Rozin-Rammler equation for the characteristics of the ore material at various points of the technological line were calculated. Originality. The proposed method of ultrasonic measurement of characteristics of the iron ore slurry in the working chamber of the magnetic separator differs from the existing ones in the fact that the Lamb wave source operates in a wide pattern and is connected by a V-shaped scheme which makes it possible to create a beam of coherent waves propagating both in the container wall (the working separator chamber) and in the measured medium (the iron ore slurry). Practical value. The practical value consists in developing an ultrasonic measuring channel scheme for determining characteristics of the iron ore slurry in the working chamber of the magnetic separator.

GPU-based SPH-DEM Method to Examine the Three-Phase Hydrodynamic Interactions between Multiphase Flow and Solid Particles

Particulate flows in a gas-liquid multiphase mixture (i.e., three-phase flows) are frequently encountered in various fields as well as the chemical engineering, resource engineering, ocean engineering, and nuclear engineering domains. Thus, the numerical modeling for such three-phase flows is essential to evaluate and enhance the fluidic design of the existing industrial devices or increase the engineering safety/efficiency. In terms of the solid particle phase, the discrete element method (DEM) has demonstrated outstanding capability in numerically modeling solid–solid interactions. For multiphase CFD model, several numerical techniques, ranging from the Eulerian–Eulerian two-fluid model to a fully resolved DNS solver, have been coupled with the DEM to model the three-phase flow. Most of the existing research on three-phase particulate flows was based on coupled grid-based CFD and DEM techniques. Considering that many three-phase particulate flows in industries are driven by a vapor/gas phase that forms a sharp interface with the liquid, coupling DEM with particle-based Lagrangian CFD methods, which can handle multi-phase flows without any interface capturing or associated correlations, can also be a good option or alternative for modeling such three-phase flows. In this respect, a three-phase flow solver was established in this study by coupling the DEM with a Lagrangian smoothed particle hydrodynamics (SPH) model while adopting the unresolved phase coupling between the two techniques. In order to overcome the low computational efficiency of these two numerical methods, GPU-based acceleration is adopted for speedup of SPH-DEM coupled solver due to its high compatibility for Lagrangian methods offered by thousands of GPU processors. The results of a scalability analysis indicated that the accelerated version exhibited an enhanced performance especially when many Lagrangian nodes are used in simulation. Several benchmark simulations were conducted to demonstrate the capability and applicability of the SPH-DEM solver in various multi-phase applications associated with particulate flows. The results of numerical simulations validated the feasibility of the momentum exchange model, and the potential and applicability of the SPH-DEM coupled solver for three-phase flow was demonstrated through a three-phase SPH-DEM simulation on the gas-driven leveling behavior of a particulate bed.

FRACTAL CHARACTERISTICS OF LOW-PERMEABILITY SANDSTONE RESERVOIRS

The sandstone micro-structure is one of the most important parameters for quantitative evaluation of groundwater/oil/gas resources and prediction of flow rates of water/oil/gas. In this study, we applied seven low-permeability sandstone samples obtained from North China to study the structures of pore and solid phase based on digital core technology and the fractal theory. In this work, rock images were collected by scanning electron microscopy (SEM), and then image software (image pro plus) was applied to convert the SEM images into binary images and calculated the perimeter and area of pores and particles. Using the fractal medium criterion, we analyzed the fractal characteristics of pore and solid phases, and then we extended the criterion from the pore phase to both pore and solid phases. This paper explores the relationship among the pore and solid phase fractal characteristics, porosity, pore size, particle size and fractal dimensions for pores and particles. The results were compared with the experimental data and showed that the solid phase satisfies the fractal distribution, while the pore phase dissatisfies the fractal distribution. It was also found that the minimum and maximum pore and particle sizes, magnification times have a significant effect on the results. In addition, by introducing the diameter and mean hydraulic radius into Ergun–Wu equation, the permeabilities of the samples were calculated.

Experimental study on fiber suspension in a centrifugal pump by PIV

Abstract To study the influence of fiber particles on the flow field within the passages of an open impeller centrifugal pump, an experiment was performed. The hair fiber was used as solid particle phase in this experiment. After measuring the performance characteristic and PIV data, the flow field in impeller was measured and analyzed. It was shown that at the concentration of 0.1%, a varied distribution of relative velocity from different flow channels was observed. The outlet velocity of the impeller in the second flow channel was obviously higher than that in the first flow channel. The variation of the relative velocity near the hub tended to be consistent at the position of the front plane and the middle plane of the impeller. At 0.2% concentration, the relative velocity at the suction surface of the two channels changes more sharply than the other positions. Within the second channel, it was found that the relative velocity under low flow condition was obviously higher than that under rated and large flow rates. Under different concentrations, the increase of the relative velocity at low flow rate changed intensely compared with the other two conditions. The low velocity zone will be formed near the middle part of the suction surface of the flow channel which gradually decreases with the increase of the flow rate. The external characteristic test shows that the efficiency of the pump and the drag reducing feature increase with the increase of concentration.

Mathematical Modeling of Changes in the Dispersed Composition of Solid Phase Particles in Technological Apparatuses of Periodic and Continuous Action

This article presents a methodological approach to modeling the processes of changing the dispersed composition of solid phase particles, such as granulation, crystallization, pyrolysis, and others. Granulation is considered as a complex process consisting of simpler (elementary) processes such as continuous particle growth, agglomeration, crushing and abrasion. All these elementary processes, which are also complex in themselves, usually participate in the formation of the dispersed composition of particles and proceed simultaneously with the predominance of one process or another, depending on the method of its organization and the physicochemical properties of substances. A quantitative description of the evolution of the dispersed composition of the solid phase in technological processes in which the particle size does not remain constant is proposed. Considering the stochastic nature of elementary mass transfer events in individual particles, the methods of the theory of probability are applied. The analysis of the change in the dispersed composition is based on the balanced equation of the particle mass distribution function. The equation accounts for all possible physical mechanisms that effect changes in particle size during chemical and technological processes. Examples of solutions to this equation for specific processes of practical importance are provided. The obtained analytical solutions are of independent interest and are in good agreement with the experimental data, which indicates the adequacy of the proposed approach. These solutions can also be used to analyze similar processes. The effectiveness has been confirmed during the analysis and calculation of the processes of granulation of various solutions and disposal of oil-containing waste to obtain a granular mineral additive.

Experimental and theoretical studies on the operating parameters of hydromechanical drilling

Purpose. To analyse certain complex components of the rock breaking act during the well construction stipulated by the design features of the technical means of hydromechanical drilling and diversity of manifestations of hydraulic and physicochemical properties of the activated circulation medium. Methodology. Physicochemical parameters of the process of active substance adsorption from the water solutions on the rock surfaces were studied in terms of their disperse material by identifying optimal ratio in the solid phase particles volume of the activated solution group with the recording of time interval of the adsorption equilibrium establishment. Features of bottomhole processes in terms of the operating modernized facilities of hydromechanical drilling were considered involving up-to-date methods of analytical analysis and experimental-laboratory studies, i.e. by using certain techniques of mathematical and physical modelling, methods for processing and interpretation of the research results by means of SolidWorks, STATGRAPHICS, D, and control-and-measuring equipment and materials. Findings. The peculiarities of the combined hydromechanical drilling technique have been analysed from the viewpoint of the creation of the most efficient conditions of bottomhole rock breaking. Since a considerable degree of the development of breaking processes is the practically proved factor of hydromechanical drilling, the rationalization and intensification of those processes may be achieved by means of controlled physicochemical effect of the surface active medium. The experimental study was carried out to analyse the directedness of the development and results of surface interaction adsorption within the boundary of phase separation as the main factor of intensification of the rock mass breaking. A comparative analysis was performed concerning the surface activity of the corresponding substances that differ in their schemes of dissociation in a water solution whose properties are to be corrected additionally to make them close to the ones peculiar for natural drill muds. Positive influence of the adsorption phenomenon on the results of contact interaction of breaking elements of hydromechanical facilities was examined; this phenomenon is shown in the decelerated wear of metal surfaces. Originality. Useful influence of the physicochemical properties of the substances under consideration decreases beginning from the ionogenic anion-active sulfonol towards the ionogenic cation-active katapin K and to the non-ionogenic substance OP-10 (-10). However, in terms of combining the compositions of the mentioned substances, it can be strengthened additionally. Practical value. The indicated laboratory and experimental studies are the basic ones to design the mode parameters of the washing programme for a hydromechanical drilling well; they belong to the main output data used while substantiating the design and technical-technological parameters of the modernized pellet impact devices.

Unified gas-kinetic wave–particle method for gas–particle two-phase flow from dilute to dense solid particle limit

A unified framework for particulate two-phase flow is presented with a wide range of solid particle concentration from dilute to dense limit. The two-phase flow is simulated by two coupled flow solvers, that is, the gas-kinetic scheme (GKS) for the gas phase and unified gas-kinetic wave–particle method (UGKWP) for the solid particle phase. The GKS is a second-order Navier–Stokes flow solver. The UGKWP is a multiscale method for all flow regimes. The wave and particle decomposition in UGKWP depends on the cell's Knudsen number (Kn). At a small Kn number, the highly concentrated solid particle phase will be modeled by the Eulerian hydrodynamic wave due to the intensive particle–particle collisions. At a large Kn number, the dilute solid particle will be followed by the Lagrangian particle to capture the non-equilibrium transport. In the transition regime, a smooth transition between the above limits is obtained according to the local Kn number. The distribution of solid particles in UGKWP is composed of analytical function and discrete particle, and both condensed and dilute phases can be automatically captured in the most efficient way. In the current scheme, the two-phase model improves the previous one in many aspects, such as drag force model, the frictional pressure formulation, and flux limiting model. The scheme is tested in many typical gas–particle two-phase problems, including the interaction of shock wave with solid particle layer, horizontal pneumatic conveying, bubble formation, and particle cluster phenomena in the fluidized bed. The results validate the GKS-UGKWP for the simulation of gas–particle flow.

Assessment of carbonyl and PAH emissions in an automotive diesel engine fueled with butanol and renewable diesel fuel blends

A comparative experimental study assessing the unregulated emissions of carbonyl compounds, polycyclic aromatic hydrocarbons (PAHs) in solid particle and gaseous phase and the contribution to ozone formation potential, was carried out for an automotive diesel engine operating under two representative urban driving conditions with butanol and renewable diesel. Both renewable fuels were blended with ultra-low sulfur diesel (ULSD) fuel to replace 13% of aromatic compounds in the reference fuel (Butanol at 13%v/v –Bu13- and Renewable diesel –RD- at 13% v/v –RD13-) and in the case of RD, an additional concentration of 20% v/v was tested (RD20). The particle and gas phase sampling procedure for PAHs characterization was carried out without any air dilution. A total of 18 PAHs (16 requested by the US EPA + benzo[e]pyrene and dibenzo[a,l]pyrene which is acknowledged for its significant carcinogenic potential) were determined. Independently of the engine operating mode, Bu13 exhibited the highest carbonyl compound emissions among all tested fuels (M1:18.8 mg/kWh of formaldehyde, M2: 18.2 mg/kWh of acetaldehyde) and the highest ozone formation potential (307 mg O3/kWh). Both RD blends exhibited similar carbonyl emissions (RD13 = 7.0 mg/kWh, RD20 = 8.3 mg/kWh) compared to ULSD (10.2 mg/kWh). Independently of the fuel and engine operating mode, most of the PAHs were present in the gas-phase, with predominance of those between 3 and 4 rings (up to 70%). No trend was observed on PAHs emissions with the addition of butanol or RD to the ULSD. It was observed that some local combustion conditions might increase the emissions of PAHs for both renewable fuels, mainly those of lower molecular weight.

Physical-mathematical model applied in the study and simulation of dissolution of sodium chloride particles in brines in upward flow in tubes

Drilling trough salt layers has been a challenge for the oil drilling industry. In this way, water-based muds are a friendly environment, although they tend to dissolve generated salt particles along with the wall of the well. Particularly, the particle dissolution may cause changes in the fluid rheology and physicochemical properties. Other problems related to this are the enlarging of the borehole, the excessive torque, the accumulation of salt gravels in the bottom hole, the well controlling issues, and some other operational situations. Thus, the controlling and prediction of the salt dissolution process in drilling fluids are of great interest. The main objective of this work was to study the dissolution of halite (NaCl) particles in brines at different concentrations on upward flow in tubes that simulate the borehole flow. An experimental apparatus was built, capable of reproducing some drilling conditions as the upward fluid flow where the data of NaCl concentration as function of position and time were obtained. A mass conservation mathematical model based on the continuum mechanic was proposed in order to simulate the process. The model was composed of two differential partial equations generated by the conservation law for the mass of salt in two phases: a fluid phase of salt dissolved in water and a solid phase of salt particles. The dissolution data were used to estimate the global mass transfer coefficient in different operational conditions and to validate the mathematical model. The total mean deviations were lower than 5 % for the proposed and validated model.

Research on Wear Characteristics and Experiment on Internal Through-Passage Components for a New Type of Deep-Sea Mining Pump

The conveyor electric pump for deep-sea mining is a key piece of equipment in deep-sea mineral transportation systems, as its flow capacity and wear resistance affect the reliability of the entire system. In this study, aimed at solving problems such as mining pumps being prone to clogging and wear, which could lead to performance degradation, a mining pump with wide flow paths and high performance was designed, and hydraulic performance tests were conducted on the new pump. The test results obtained were in good agreement with the numerical simulation results. Based on the reliability of the performance test results, using computational fluid dynamics (CFD) methods, and taking the wear model into consideration, a wear analysis was conducted on the internal through-passage components of the pump under different solid-phase particle parameters and operating conditions, and the average wear rate on the surface of the predominant through-passage components was calculated. The results showed that the hydraulic performance of the newly designed pump met the design requirements, with different particle parameters and operating conditions causing different degrees of wear on the through-passage components. The wear test was carried out with a test pump, and the comparison between the test results and the numerical calculation results showed that the numerical calculation of the wear of the deep-sea mining pump was accurate.