Liquids Of Different Densities Research Articles

Liquid separation modeling while selecting contact devices for separation in a centrifugal field

This paper proposes the use of mathematical modeling of technological processes as a tool for increasing the efficiency of equipment and solving environmental problems, which contributes to the sustainable development of enterprises in the chemical industry. The results of modeling the process of separating liquids of different densities in a centrifugal field are presented to study the influence of the type of atomizers on the flow rate and the number of contact devices on the separation efficiency. The work shows the importance of using numerical modeling in design to substantiate scientifically decisions made and confirm the effectiveness of developed structures. The results are important to intensify heat and mass transfer processes and to reduce the negative impact of production on the environment.

Elutriation characteristics of binary particle mixture in pseudoplastic liquid: Empirical correlation and GA-ANN modelling

The elutriation of the binary mixture from irregularly shaped particles with different diameters in non-Newtonian liquids of different densities has been investigated in an SLFB (Solid Liquid Fluidized Bed). The influence of various parameters like particle size of the binary mixture, column diameter, bed weight and rheological properties of the non-Newtonian liquid on minimum elutriation velocity (Ume) have been carried out experimentally. It has been found that Ume increases as column diameter and particle size increase while decreasing when SCMC concentration increases. An empirical correlation was developed to predict the minimum elutriation velocity associated with suitable statistical parameters. GA-ANN (Genetic Algorithm and Artificial Neural Network) modelling was successfully employed.

Способи сепарації на підготовчій стадії проведення криміналістичної експертизи речових доказів

In expert practice, questions often arise related to the separation (separation) of research objects from a mixture of dissimilar particles of solid materials, liquids of different densities, emulsions, two-phase media. During the study, physical and chemical separation methods are used. The choice of the separation method depends on the percentage composition and properties of the mixture and its constituent components. Expert research is carried out using various methods of separation: by mass (inertial), by size, electrical, magnetic, radiometric, photometric, etc. Chemical separation is its separate type. Analysis of expert practice indicates that separation is mainly applied during the forensic investigation of metals and alloys (solids), drugs (solids, liquid substances) and petroleum products (liquid substances). The article analyzes the methods of separation at the preparatory stage of the expert study of microparticles of precious metals and handicraft drugs. Forensic investigation of metal and alloy products is one of the most difficult, since the detection and separation of microparticles of the metal under study from other metal particles and their subsequent identification require the use of both chemical and instrumental research methods. The separation of the metal under study from the mixture of other metal particles was carried out by the method of mechanical and magnetic separation and chemical (selective dissolution) separation. During the expert study of acetylated opium using chromatographic methods, difficulties often arise associated with the separation of components due to the presence of a large amount of ballast substances (in particular, chlorophyll) extracted from poppy straw in acetylated opium. The use of an inertial separation method makes it possible to speed up the separation of an aqueous solution of a narcotic drug emulsion and an extracting organic solvent.

Study on multilayered liquids sloshing tank subjected to sway and roll excitation

Herein, analytical and numerical approaches are used to investigate the interfacial surface elevations by a swaying and rolling tank with multilayered liquids of different densities. The analytical model, formulated using the eigenfunction expansion method based on two-dimensional linear potential theory, incorporates artificial damping to account for energy dissipation due to friction at the walls and bottom. The analytical model is used to predict the wave elevations and hydrodynamic forces on the tank as well as the natural frequencies of multilayered liquids. In parallel, computational fluid dynamics (CFD) is used, which employs quasi-two-dimensional implicit unsteady, incompressible Navier-Stokes equations. The volume of fluids technique is used to track the interfacial surfaces along with high-resolution interface capturing and interface momentum dissipation techniques. The interfacial surface elevations at the tank wall agree well with the analytical and CFD results, with the expected resonant peaks. Fourier analysis estimates added mass and damping coefficients for the three-layered tank from the total force. CFD results for the three-layered liquids exhibit strong nonlinear wave elevations at the interfaces. Power spectral density (PSD) analysis reveals higher harmonics in CFD solutions as tank amplitude increases.

Dynamics of a clamped drop under translational vibrations

The free and forced translational oscillations of an ideal liquid drop have been investigated. The drop was placed in a large-sized vessel filled with a liquid of different density. In equilibrium, the drop has the shape of a circular cylinder, and it is sandwiched between the lid and bottom of the vessel. The contact line-speed at the end plates is proportional to the deviation of the contact angle from its equilibrium value (the angle is formed by the corresponding plate and the undeformed cylindrical surface of the drop). The proportionality coefficient (the wetting or Hocking parameter) is different for each surface; it characterizes the force of interaction between the contact line and the solid surface, which leads to energy dissipation during its movement. This makes it possible to use the velocity potential to describe motion in the presence of a deformed interface between inviscid fluids. It is shown that the fundamental frequency of the translational mode of natural oscillations may not vanish in contrast to the case of equal wetting parameters. The energy dissipation is determined by the total contribution of these parameters, which makes it possible to vary the motion of the contact line over a wide range. The oscillation amplitude is proportional to the density difference of the liquids, i.e., at equal densities, the system moves as a whole. It has been found that both integer and non-integer harmonics of shape oscillations are excited due to different wetting parameters. The external vibrational force excites only even harmonics and, with identical surfaces, only they are present in the oscillation spectrum.

Dynamics of two liquids in a non-uniformly rotating horizontal cylinder

Controlling the shape of the interfacial boundary is an important technological task. The effect of rotation velocity modulation on the interface between light viscous and denser low viscosity fluid in a rotating horizontal cylinder is studied experimentally. Liquids are characterized by a high contrast of viscosities, these are glycerin and a low-viscosity (denser) fluorinert FC-40. Glycerin is stained with rhodamine, which makes it possible to study the shape of the interface by photo registration with high accuracy when illuminating liquids with a green laser, which causes rhodamine fluorescence. Experiments are carried out in the centrifuged state of liquids when the gravity field has no effect while varying the rotation speed, as well as the amplitude and frequency of librations. It is found that librations qualitatively change the shape of the interface near the ends of the cavity without affecting the cylindrical interface in the middle cavity part. It is shown that this is due to different "viscous" interactions of liquids with the ends of the oscillating cavity, as a result of which the interface near the ends performs radial oscillations with a frequency of librations, and the latter leads to an averaged radial displacement of the wetting boundary of the ends, which increases with the modulation amplitude. At certain amplitudes, the contact line reaches the outer boundary of the cavity. It is shown that the dynamic equilibrium of the interface between liquids of different densities is determined by the averaged interaction of liquids of different viscosity with the oscillating ends.

Development and Performance of Hydrocyclone Separator for Biodiesel Production

Hydrocyclone is an equipment that uses a cyclone or tangential injection flow process with centrifugal forces to separate liquids of different densities. The denser liquid move downwards in a spiral path into an underflow chamber, while clean liquid which is less dense move upwards to the center of the spiral, towards the top outlet. Colman and Thew’s hydrocyclone geometry analysis approached was used in the design and the assumed inlet chamber diameter (D) used for this design was 150 mm and a reducing section length of 1500 mm at a reducing angle of 20°. The capacity of the designed hydrocyclone system in volume is 5.5 liters. The developed machine was tested with 15 liters of palm kernel oil (PKO) as raw material using two different pressures gauge (70 and 80 kPa) and also effect acid concentration (sulphuric acid) at 3 different experimental runs. After the experiments, it was deduced that at constant temperature level, as the pressure rate increases, there is a corresponding increase in the discharge rate at the underflow and overflow outlets where 2.04 minutes and 1.67 minutes were used to separate biodiesel and glycerin under 70 and 80 kPa respectively. Also, it was deduced experimentally that PKO with sulphuric acid gives a higher yield of biodiesel of 47.74% while the one without has 38.49% yield under same experimental and operational conditions.

Robustness evaluation of optimum tuned liquid dampers for uncertain variable loading of structures

This study focuses on the performance analysis of optimum tuned liquid dampers (TLDs) under the different live loads of three different structure models, designed as both single and multi-story, under earthquake excitations. For this purpose, single, ten, and forty story structure models have been created and tuned liquid damping devices that contain liquids of different densities and viscosities such as acetone, mercury, and seawater are placed on the structure. For the analysis conducted under earthquake excitations, optimum damping device parameters were previously obtained with the Adaptive Harmony Search Algorithm (AHS), and minimizing the movement of the structure was aimed. The effect of the damping device on the control performance was investigated under increasing and decreasing live loads for the uncertain mass of the structure because of variable actions. When the results are examined, it has been determined that the increase in the story number of the structure will less affect the displacement reduction performance of TLDs for the structure under uncertain variable loading.

Development and Validation of a Design Tool for an Improved Pitot-Tube Jet-Pump Allowing Continuous Fluid-Fluid Separation

Abstract A pitot-tube jet-pump (PTJ pump) has been considerably modified and extended in order to continuously separate and transport liquids of different densities. As a first application, an oil–water mixture is considered in this work. The modified PTJ pump could be used as a primary separator for oil-polluted water (e.g., around off-shore platforms, after oil spills from ships), while additionally being able to transport the resulting fluid to further heaters, exchangers, centrifuges, distillation columns, etc., without necessitating additional machinery. The performance behavior of the separating PTJ pump (abbreviated SPP in what follows) has been first investigated with computational fluid dynamics (CFD), and then validated by comparison with experimental data acquired on a small-scale prototype. Based on these observations, a design tool has been developed to (i) predict performance and (ii) support proper device scaling. This tool is based on dimensionless parameters that are already employed for classical turbomachinery, similar to the Cordier chart. However, since the SPP works at an extremely low specific speed, its operating points lie outside the standard Cordier chart. To verify the accuracy of the design tool, a scale-up test has been conducted and validated by CFD, delivering a good agreement. A separation efficiency better than 99% has been obtained in the experiments for suitable operation conditions, while the numerical scale-up test reveals a head of 15.1 m and an oil content below 0.2% in the purified water at the high-pressure outlet.

Vortex fluidic induced mass transfer across immiscible phases.

Mixing immiscible liquids typically requires the use of auxiliary substances including phase transfer catalysts, microgels, surfactants, complex polymers and nano-particles and/or micromixers. Centrifugally separated immiscible liquids of different densities in a 45° tilted rotating tube offer scope for avoiding their use. Micron to submicron size topological flow regimes in the thin films induce high inter-phase mass transfer depending on the nature of the two liquids. A hemispherical base tube creates a Coriolis force as a ‘spinning top’ (ST) topological fluid flow in the less dense liquid which penetrates the denser layer of liquid, delivering liquid from the upper layer through the lower layer to the surface of the tube with the thickness of the layers determined using neutron imaging. Similarly, double helical (DH) topological flow in the less dense liquid, arising from Faraday wave eddy currents twisted by Coriolis forces, impact through the less dense liquid onto the surface of the tube. The lateral dimensions of these topological flows have been determined using ‘molecular drilling’ impacting on a thin layer of polysulfone on the surface of the tube and self-assembly of nanoparticles at the interface of the two liquids. At high rotation speeds, DH flow also occurs in the denser layer, with a critical rotational speed reached resulting in rapid phase demixing of preformed emulsions of two immiscible liquids. ST flow is perturbed relative to double helical flow by changing the shape of the base of the tube while maintaining high mass transfer between phases as demonstrated by circumventing the need for phase transfer catalysts. The findings presented here have implications for overcoming mass transfer limitations at interfaces of liquids, and provide new methods for extractions and separation science, and avoiding the formation of emulsions.

Heat transfer in a centrifugal vortex tube

The results of an experimental study of the heat flux in a model of a centrifugal vortex apparatus with a lower rotating disk are presented. An experiment considered three cases at a distance between the disks H=R/2 and H=R: “water”, “water-air”, and “water-oil”. Using the colorimetric method, the dependence of the heat flux on Reynolds is shown. The case “water-air” was chosen to evaluate the contribution to heat exchange from the thermocapillary effect (Marangoni) at high Re. For the case of two immiscible liquids of different densities (water-oil), the effect of “centrifugal levitation” is found.

Fluorescence Imaging Methodology for Oil‐in‐Water Concentration Measurements

AbstractA Pitot‐tube jet pump for separating and transporting liquids of different densities is in use for processing oil‐polluted water. The remaining oil‐in‐water (OiW) concentration is a main indicator for the process efficiency and requires a precise measuring method. Hence, a simple approach delivering reliable oil concentrations has been developed in this project. The measurement principle relies on the image acquisition of an OiW emulsion, where the oil phase is seeded with a selective dye tracer. In this concept study, a detailed description of the preparation procedure is provided. Suitable operation parameters leading to sufficiently stable emulsions have been obtained. Finally, a calibration function was determined. It can be used to correlate uniquely the image intensity to the oil concentration.

Assessment of coal sortability and washability using dual energy X-ray transmission system

ABSTRACT Sorting coal using x-ray transmission sensors has been explored since 1972 by Jenkinson et al. Coal sortability is assessed using washability derived from dual-energy X-Ray transmission (DE-XRT) system. Coal sorting is considered to be dry separation of coal that can be carried out before coal is send to the processing plant. It can act as deshaling/destoning process or it can also be used to selectively mine shallow coal seams to avoid overburden contamination hence dilution. There are a few commercial concepts in the coal industry which utilizes the XRT sensors to sort the coarse particle coal. In order to define final product quality in terms of ash as well the efficiency of any separation based on density such as yield, washability is used to determine the separation process parameter such as density of separation, e.g. specific gravity. Washability characteristics have been traditionally assessed using the float-sink (washability) tests. These analyses determine how much of coal can be separated from associated rock (mineral matter) in liquids of different densities. However, the test work requires a wet processing where organic liquids, referred to as heavy liquids are used. The test work is very time consuming as it requires significant amount of time to complete full washability for a wide spectrum of coal particles. To avoid using toxic chemicals and save time, the DE-XRT can easily become an alternative method to assess the washability of coarse coal before the coal is processed by sorting to establish separation parameters and obtain information about the yield of clean coal of desired quality in terms of ash content. In this project in order to assess effectiveness of DE-XRT for sorting and at the same time to derive the washability data for the coarse coal, the test work has been designed to test various lithotypes identified from coarse coal sample. As a result, the test work included classification of coal lithotypes (larger pieces of coal of certain petrographic composition), density measurement using both DE-XRT and float-sink tests and ash analysis. The results are compared to float-sink tests for coarse coal fractions obtained by proxy washability analysis derived from pycnometry. Similar to float-sink tests, the DE-XRT can estimate a relative density by measuring the attenuation of x-rays from two different energy levels. The paper explains the basics of the DE-XRT analysis and its data processing methods to determine the relative densities and how to derive washability curves and density of separation for coal sorting. The basic principle of dual-material decomposition is adopted from Dual-Energy CT in the medical industry where the sum of each vector provides a proportion of the two material.

Stability of interface between liquids with high viscosity contrast in unevenly rotating cavity

The effect of modulation of the cavity rotation rate on the interface of liquids of different densities and high viscosity contrast is studied experimentally. The cavity is a short horizontal cylinder rotating around its axis. The end walls of the cavity form a narrow gap. Under uniform rotation the interface has an axisymmetric shape. With the modulation growth, the axisymmetric boundary loses stability. Instability manifests itself in the appearance of a regular quasistationary relief at the interphase. The relief excitation is associated with the Kelvin-Helmholtz instability. Tangential velocity discontinuity under modulation arises due to various interaction of liquids with the cavity end walls because of viscosity contrast. The viscosity contrast, on the one hand, is responsible for tangential velocity discontinuity; on the other, it has a significant effect on the threshold of Kelvin-Helmholtz instability. It results in decrease of stability threshold and an increase of relief wavelength.

Investigation of the structural characteristics of vitrinites of some coals of the Kuznetsk Basin

In this work, the structural parameters of vitrinites of coal of various degrees of metamorphism were investigated by X-ray diffraction methods. Vitrinite concentrates were obtained from coal of the Kuznetsk Basin by the method of fractional analysis of coals, according to which the studied fuel is stratified into fractions in liquids of different densities. The following X-ray structural parameters were analyzed: the number of carbon atoms in the lamellae (natC), the longitudinal size of the lamellae, the height of their stacking (La and Lc), the number of polyaromatic layers in the stack (N), and the packing density of the lamellae (ρ). It was shown that in vitrinite concentrates, an increase in all analyzed structural parameters (Lc, La, natC, N, ρ) is observed with an increase in the degree of metamorphism, at the same time, a decrease in the value of the interplanar distance (d002) is observed. The performed X-ray diffraction studies showed that the average number of layers in a package and carbon atoms per monolayer in the samples of vitrinite concentrates of bituminous coals of high stages of metamorphism (Ro, r = 1.41%) varies from 7 to 8 and 14-15, respectively. A correlation was found between the linear nature of the number of arene layers and the height of their packing. The results obtained are in good agreement with the literature data given for coals of various deposits.

METHODS OF SEPARATION AT THE PREPARATORY STAGE OF CRIMINAL EXAMINATION OF MATERIAL EVIDENCE

In expert practice, questions often arise related to the separation of research objects from a mixture of dissimilar particles of solid materials, liquids of different densities, emulsions, and two-phase media. During the study, physical and chemical separation methods are used. The choice of the separation method depends on the percentage composition and properties of the mixture and its constituent components. Expert research is carried out using various separation methods: by mass (inertial), by size, electrical, magnetic, radiometric, photometric, etc. Chemical separation is its separate type. The analysis of expert practice indicates that separation is mainly applied during the forensic investigation of metals and alloys (solids), drugs (solids, liquid substances) and petroleum products (liquid substances). The article analyzes the methods of separation at the preparatory stage of the expert study of micro-particles of precious metals and handicraft drugs. Forensic investigation of products made of metals and alloys is one of the most difficult, since the detection and separation of micro-particles of the metal under study from other metal particles and their subsequent identification require the use of both chemical and instrumental research methods. The separation of the metal under study from the mixture of other metal particles was carried out by the method of mechanical and magnetic separation and chemical (selective dissolution) separation. In the course of the expert study opium acetylated using chromatographic methods difficulties often arise associated with separation of components due to the presence of large amounts of acetylated opium extractable from poppy straw ballast substances (in particular chlorophyll). The use of an inertial separation method makes it possible to speed up the separation of an aqueous solution of a narcotic drug emulsion and an extracting organic solvent.

Float-laser device for measuring the water table and freshwater–saltwater interface in laboratory-scale experimental systems

Processes in coastal aquifers involving variable-density fluids are often investigated using laboratory sand tanks. However, experimental monitoring of the interface between liquids of different densities is challenging, typically requiring dye tracers and photographic analysis. These are susceptible to problems of tracer adsorption and image inhomogeneity, and experiments are often limited to two-dimensional cross-sections. In addition, the water-table position is an important factor, but its accurate measurement is often difficult. A device has been developed for sand-tank experiments to obtain high-frequency, high-precision measurements of both the freshwater–saltwater interface (inferred from density) and the water-table depth, using a float and a laser sensor in a monitoring well. The proposed device was tested using a two-column experiment, allowing for the estimation of measurement errors, which were generally less than 1 mm. The measurement device can be modified to allow for the monitoring of multiple salinity values, and is well suited to sand-box experiments where salinity dynamics are otherwise difficult to visualize.

Fully Differential Actuation and Sensing in Piezoelectric Diaphragm Resonators for High Signal to Background Resonant Sensing

We report a successful realization of a self-actuating and self-sensing piezoelectric diaphragm resonator for sensing applications with high signal to background ratio (SBR). A fully differential electrode topology is designed for actuation of the diaphragm in the first flexural mode, and for simultaneously sensing the resulting vibrational response. The electrical (sense) outputs from the resonator (of radius 1000 μm and thickness 25 μm) in two different experimental arrangements - partial differential and fully differential - are compared with the mechanical vibration response obtained from a laser Doppler vibrometer. The effect of poling on electrical crosstalk for the fully differential operation is investigated. The resonator suffers from electrical crosstalk even in fully differential operation when characterized without poling the PZT thin film. The sense output from the resonator after poling, when actuated using a differential electrical input of 0.5 Vpp, is measured both in-air and in liquids of different densities. In the self-sensing mode, the peak output from the device at the first flexural mode resonance is 2-3 mV in different density liquids and ~9 mV in air. The resonator is also characterized as a resonant sensor for liquid density measurements. The sensitivity of the device is found to be 11.9 Hz/(kg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). The corresponding sensitivity in parts per million is calculated to be ~454 ppm/(kg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) with the resonance frequency in DI water (26.3 kHz) as the reference.

Concentric liquid reactors for chemical synthesis and separation

Recent years have witnessed increased interest in systems that are capable of supporting multistep chemical processes without the need for manual handling of intermediates. These systems have been based either on collections of batch reactors1 or on flow-chemistry designs2-4, both of which require considerable engineering effort to set up and control. Here we develop an out-of-equilibrium system in which different reaction zones self-organize into a geometry that can dictate the progress of an entire process sequence. Multiple (routinely around 10, and in some cases more than 20) immiscible or pairwise-immiscible liquids of different densities are placed into a rotating container, in which they experience a centrifugal force that dominates over surface tension. As a result, the liquids organize into concentric layers, with thicknesses as low as 150 micrometres and theoretically reaching tens of micrometres. The layers are robust, yet can be internally mixed by accelerating or decelerating the rotation, and each layer can be individually addressed, enabling the addition, sampling or even withdrawal of entire layers during rotation. These features are combined in proof-of-concept experiments that demonstrate, for example, multistep syntheses of small molecules of medicinal interest, simultaneous acid-base extractions, and selective separations from complex mixtures mediated by chemical shuttles. We propose that 'wall-less' concentricliquid reactors could become a useful addition to the toolbox of process chemistry at small to medium scales and, in a broader context, illustrate the advantages of transplanting material and/or chemical systems from traditional, static settings into a rotating frame of reference.

Experimental studies of the transport speed of immersion of pea grains in liquid

The basis of leguminous crops is peas, which have a food value for human nutrition. Peas are also used as concentrated and green feed, silage, hay, and hay flour. Pea seeds are susceptible to various diseases. One of the main reserves for increasing the production of pea grain is the use of seeds that are cleared of various impurities for sowing and pre-treatment with chemical preparations against pathogens. An effective method of protecting pea seeds from various diseases is wet treatment with bactericidal preparations with the simultaneous use of biologically active substances. To develop a device for processing seeds by wet method, research was conducted on the transport speed of immersion of spherical grains in liquid. When conducting practical experiments, we considered the movement in a liquid with a density of ρzh = 1000, 1090 and 1150 kg/m3 of individual pea grains of the Vita variety (spherical shape) with a moisture content of 14%. Sodium chloride salt (NaCl) was used to change the density ρzh of the liquid. To obtain more reliable information, the experiments were performed three times over. The temperature of the surrounding air and liquids of different densities was 20 °C. The data obtained were processed using one of the methods of variation statistics. It was found that in water (ρzh = 1000 kg/m3) the confidence interval of the transport speed of immersion of single grains with a reliability of, and in an aqueous solution of sodium chloride (NaCl) with a density of ρzh = 1090 and 1150 kg/m3, respectively, 0.10-0.28 m/s and 0.09-0.23 m/s. This approach to determining the transport speed of grain immersion in liquid can be used in the development of a machine for etching pea seeds using a wet method.