Electric Dehydration Research Articles

Influence of constant and alternating electric fields on the deformation and destruction of a liquid droplet

Examining the impact of electromagnetic field, which provides thrust in contemporary rocket engines, is turning into a significant issue. Its resolution is required to guarantee the safety of space flight by enhancing engine performance and lowering fuel consumption. Spacecraft propulsion is achieved by low-thrust rocket engines. The principle of operation for ion colloid engines is the electrostatic acceleration of charged droplets. A static electric field accelerates charged liquid droplets created by electrospraying them in a low-thrust colloid engine. A promising technology in many industries is the active control of droplet motion and deformation with electric field. An electromagnetic field impact on droplet deformation and destruction in a viscous liquid is examined. The effect of electromagnetic field on individual droplets and emulsions is examined in terms of their physical mechanisms. Constant and alternating electric field effects on liquid droplet are represented numerically. The effects of droplet electric capillary number and viscosity ratio on droplet unsteady deformations is explored. The parameters that correspond to the droplet destruction are found. The results obtained have potential applications in enhancing the efficiency of current industrial electric dehydrators and in advancing the development of new electromagnetic field-based demulsification technologies.

Microwave-assisted dehydration of strontium hydroxide octahydrate: Experimental study and kinetic modeling analysis

In this context, the present study proposes the use of microwave irradiation to improve the dehydration rate and efficiency of strontium hydroxide octahydrate (Sr(OH)2·8H2O) without introducing contaminants. This study revealed that the use of microwave irradiation to dehydrate Sr(OH)2·8H2O is feasible and surprisingly efficient. The effects of this approach on important parameters were investigated using response surface methodology (RSM). The results revealed that the microwave dehydration process follows a linear polynomial model. In addition, compared with the heating time and material thickness, the microwave-assisted dehydration of Sr(OH)2·8H2O is sensitive to the microwave power and not to the material mass. The relative dehydration percentage reached 99.99% when heated in a microwave oven at 950 W for just 3 min. In contrast, a relative dehydration percentage of 94.6% was reached when heated in an electric furnace at 180 °C for 120 min. The XRD spectra also revealed that most of the Sr(OH)2·8H2O transformed into Sr(OH)2 after dehydration via microwave irradiation, whereas a significant portion of the Sr(OH)2·H2O remained after conventional electric dehydration. The experimental data were fitted and analyzed via the thin-layer drying dynamics model, and the results indicated that the dehydrating behavior of Sr(OH)2·8H2O could be well described by the Page model.

Electric dehydration of coal tar – a by-product of coke production for blast furnace smelting

Electric dehydration of coal tar – a by-product of coke production for blast furnace smelting

Design, Build, and Analyze: A Comprehensive Approach to Developing a Thermal Dehydrator Prototype

Abstract: Fruit and vegetable preservation commonly relies on drying methods, and dehydrators play a pivotal role in enhancing traditional sun-drying processes. This report delves into the intricate calculation and analysis of a specific household electric dehydrator model with a 5kg capacity. Employing a meticulously chosen 5 kg sample of grapes with an initial 80% w.b(wet basis). moisture content, the dehydrator was analysed at temperatures of 45, 50, and 60 degrees Celsius.

Falling, deformation, and coalescence of droplet in model waxy oil under an electric field

Electrocoalescence technology can efficiently dehydrate waxy crude oil but the mechanisms are still unclear. Herein, the continuous microscopic behaviors of droplet falling, deformation, and coalescence were experimentally investigated to clarify the dynamic response mechanism of droplet in waxy oil under an electric field. The results showed the droplet falling under both gravity and electrostatic attraction to deform by the electric field force. Moreover, the expansion and clamping of the liquid bridge resulted from the competition between electric field force and capillary force. However, the precipitated wax crystals reduced the kinetic energy of the droplet and affected its external circulation, thus delaying the falling time. In addition, the wax crystals with interfacial activity adsorbed on the oil-water interface and cross-linked to form a spatial network structure, thereby weakening droplet deformation, hindering liquid film drainage, and inhibiting liquid bridge expansion. Importantly, the droplet adsorbed wax crystals exhibited interfacial elasticity, which makes them more inclined to partial coalescence. The low-frequency pulsed direct current (PUDC) electric field with high strength intermittent effect displayed the most obvious inhibition effect on the wax crystals. Overall, these findings look promising for future design and optimization of high-efficiency electric dehydrators and related fields.

Synchronous magnetization to weaken the hindrance of surfactants to droplet coalescence during electric dehydration

Electric dehydration is the most widely used physical technology for separating water from crude oil. However, natural surfactants stabilize the oil–water interface, resulting in low dehydration efficiency and failure of the electric dehydrator due to electric field collapse. To explore the physical methods of weakening the influence of surfactants on electric dehydration, this study synchronously increased magnetization during the electric dehydration. Based on high-speed microscopy experiments, it has been demonstrated that synchronous magnetization weakens the hindrance of surfactants to droplet coalescence during electric dehydration. Within the experimental conditions, the influence of magnetization on the growth coefficient C1 ranges from 2.9% to 26.6%. In addition, based on molecular dynamics simulation, the mechanism of magnetization weakening the influence of surfactants was studied at the molecular level. It was found that water molecules and surfactant molecules undergo significant molecular clusters after magnetization, reducing the influence degree of surfactants on unit area. When the surfactant concentration increases, the decrease in the influence degree is balanced by the increase in the number of molecules, which also explains the law that the improvement rate ΔC1 decreases with the increase in surfactant concentration. The results of this work will be potentially valuable for weakening surfactant barriers to demulsification and oil–water separation.

Achieving High Power Density and Durability of Multilayered Swing‐Structured Triboelectric Nanogenerator toward Marine Environmental Protection

AbstractProtecting marine environment is an important and urgent task to maintain marine ecological balance. As a promising blue energy harvesting technology, triboelectric nanogenerator (TENG) can provide electrical energy for marine environmental protection. Previous reported swing‐structured TENGs have advantages of low driving force in low‐frequency water waves and strong durability, but the space utilization and volume power density are relatively low. Here, a multilayered swing‐structured TENG (MS‐TENG) with low wear is designed to increase the space utilization rate, and thereby enhance the output performance. The MS‐TENG generates the highest peak power density of 15.18 W m−3 Hz−1 and average power density of 3.56 W m−3 Hz−1 under water wave triggering at 0.8 Hz. By coupling the charge pumping and non‐contact mode of main TENGs, the MS‐TENG achieves strong performance stability, exhibiting little attenuation of electric output after 240 000 cycles. Furthermore, the MS‐TENG has successfully powered a water quality detector for self‐powered ballast water quality monitoring, and an application is presented about electrical dehydration of water‐in‐oil emulsions driven by the MS‐TENG with a dehydration rate of 99.6%. This work promotes the development of high power density MS‐TENG and demonstrates its application potential for self‐powered marine environmental protection.

Effect of electric field strength and droplet diameter on droplet–interface coalescence mechanism

Under high-strength electric fields, partial coalescence may occur, thus producing fine secondary droplets, which are undesirable for separating water from oil. In this study, experimental and numerical methods are employed to investigate the coalescence behavior under a DC electric field to comprehensively understand the effect of electric field strength (E) and droplet diameter (D) on coalescence. The Level-set method is employed to capture the moving interface, and the numerical data are validated through experimental tests. The results reveal the easy formation of secondary droplets with increasing E and D values. In particular, the electric field strength suppresses the expansion of the liquid bridge and hinders the vertical collapse of the droplets. The distortion of the electric field at the liquid bridge and the polarized charge both increase with E, thus resulting in stronger electric field repulsion. Moreover, the enhancement in D significantly affects the shrinkage of the liquid bridge and prevents the vertical collapse of the droplet. The pressure gradient at the liquid bridge from the outside to inside decreases as a function of D, thereby inhibiting the contraction speed. Furthermore, the number of polarized charges concentrated on the top of the droplet increases, thus resulting in an enhanced electric field tension. The results obtained herein can potentially act as guide for the design and optimization of electric dehydrators.

Electrical dehydration performance of shale oil: From emulsification characteristics to dehydration mechanisms

Shale oil, as a successor to ordinary crude oil, has received extensive attention. However, the high-stability shale oil emulsions are still challenging for electrical dehydration systems. In this work, the differences between shale oil and ordinary crude oil were compared in terms of emulsion droplet size, physical properties and components to clarify the emulsification characteristics of shale oil and reveal its electrical dehydration mechanism. To this end, comprehensive electrical dehydration experiments were carried out under different parameters and transformers. The results showed droplet diameters of shale oil emulsions less than 10 µm, a value much smaller than that of crude oil. Shale oils with high viscous contained lots of natural emulsifiers, promoting the formation of the rigid asphalt film and wax crystal network structure. The synergistic adsorption of surfactant and paraffin molecules and the film formation of asphaltenes promoted by resins make shale oil display lower interfacial tension and higher interfacial film pressure. The above characteristics were the main reasons behind the formation of shale oil stable emulsions. Factors, such as electric field frequency, dehydration temperature, dehydration time, and demulsifier concentration influenced the emulsification characteristics and dehydration performance of shale oils at variable degrees. The dehydration performances of high-frequency transformer (Transformer B) and ultra-high-frequency transformer (Transformer C) on shale oil emulsion SH-1 were better than that of low-frequency transformer (Transformer A) due to tensile breakup or oscillatory coalescence of droplets under different electric field conditions. Considering energy consumption and economy comprehensively, Transformer C has excellent application potential. The analyses also show that high-frequency, heating and adding demulsifier are the key and necessary factors in the electric dewatering treatment of shale oil. In sum, these results look useful for future design optimization of shale electrical dehydration devices.

Modelling of high performance electrocoalescer based on experimental data

Modern approaches to automatic control of crude oil dewatering and desalting are predominantly model-free, and described model-based systems lack precise mathematical description. Not a single research provides a dynamic input-output model for electric dehydrator, suitable for control system development. As far as electric dehydrator, which is the main plant to control in the process, is a non-linear system with distributed parameters, a need for linearization arises. The aim of present study is to compare different methods for obtaining approximate transfer function of an electric dehydrator from graphical experimental data.

Probing the Demulsification Mechanism of Emulsion with SPAN Series Based on the Effect of Solid Phase Particles.

The solid particles in the produced fluids from the oil wells treated by compound flooding can greatly stabilize the strength of the interfacial film and enhance the stability of the emulsion, increasing the difficulty of processing these produced fluids on the ground. In this paper, the oil phase and the water phase were separated from the SPAN series emulsions by electrical dehydration technology and adding demulsifier agents. The changing trends of the current at both ends of the electrodes were recorded during the process. The efficient demulsification of the emulsion containing solid particles was studied from the perspective of oil-water separation mechanisms. Combined with the method of molecular dynamics simulation, the effect of the addition of a demulsifier on the free movement characteristics of crude oil molecules at the position of the liquid film of the emulsion were further analyzed. The results indicated that the presence of solid particles greatly increased the emulsifying ability of the emulsion and reduced its size. Under the synergistic effect of demulsifier and electric dehydration, the demulsification effect of the emulsion increased significantly, and the demulsification rate could reach more than 82%. The addition of demulsifiers changed the stable surface state of the solid particles. The free movement ability of the surrounding crude oil molecules was enhanced, which led to a decrease in the strength of the emulsion film so that the water droplets in the emulsions were more likely to coalesce and break. These results are of great significance for the efficient treatment of wastewater from oilfields, promoting the sustainability of environment-friendly oilfield development.

Investigation of droplet pairs’ movement under the electric field generated by matrix electrodes

Electric dehydration technology has gained lots of attention as an oil-water separation technology that has only been around for a short time. Many research scholars have studied the laws of droplet motion in electric fields. However, previous research on the droplet motion law in a non-uniform electric field has only focused on the single droplet, ignoring the dipole-dipole interaction between droplets, which plays an important role in the droplet coalescence process. In this paper, the motion of droplet pairs in a non-uniform matrix electric field is studied by means of theoretical analysis and numerical simulation. A mathematical model of the migration velocity and coalescence time of droplet pairs was established. The results show that the migration velocity of droplet pairs under dielectrophoresis and dipole-dipole interactions is significantly greater than that of single droplets and that the droplet velocity is related to the electric field strength, continuous phase viscosity, droplet diameter, and droplet pair center distance. This study increases our understanding of droplet electrocoalescence kinetics, enriches the electrocoalescence mechanism of droplets under non-uniform electric fields, and provides a basis for the design of subsequent electrodehydration equipment.

Microscopic stabilization mechanism of nanoparticle-laden droplets under external electric fields: A molecular dynamics study

Electric dehydration process of crude oil is frequently accompanied by water droplet breakup, resulting in efficiency reduction of oil-water separation. To reveal the microscopic stabilization mechanism of nanoparticle-laden droplet, molecular dynamics (MD) simulations were adopted to investigate the electro-deformation and breakup dynamics. Good qualitative and quantitative agreements were observed between the present simulations and the literature experiments. The effects of electric fields (electrocapillary numbers and frequencies) and nanoparticles (concentrations and types) on the droplet stability were analyzed in terms of intermolecular total interactions. The analysis of quantum chemical calculations and weak interactions shows that stable hydrogen bonds can be formed between the silicon dioxide (SiO2) and water (H2O) molecules, enhancing droplet stability. The droplet stability under alternating current (AC) electric fields are higher than that under direct current (DC) electric fields, and the stability increases with increasing AC frequencies. At the total interactions of the nanoparticle-laden droplet system after switch-off electric field stronger than that after switch-on electric field, fast droplet recovered process was observed. The modified SiO2 NPs can efficiently enhance droplet stability, and high nanoparticle (NP) concentrations lead to high droplet stabilities. Eventually, the ranking of NP-laden droplet stabilities is roughly consistent with that of droplet pair electrocoalescence efficiencies, i.e., CAC (SiO2 modified with 6 carboxylic acid chains) > CAAL (SiO2 modified with 3 carboxylic acid chains and 3 alkane chains) > ALC (SiO2 modified with 6 alkane chains) > SiO2. The results of this work will be potentially valuable for optimizing the design of compact and efficient oil-water separators.

Research on The Performance of A Novel Compact Electrostatic Separator: From Laboratory Experiment to Oilfield Test

ABSTRACT Water cut of oil well stream becomes high and crude oil emulsions are more stable and complex as most oilfields are in middle and late exploitation stage. It is difficult to meet the outlet oil quality requirement by using conventional electric dehydrator with bulky tank configuration in crude oil dehydration process. In this paper, we developed a novel compact electrostatic separator (CES) which combines the effect of electric field, centrifugal field and gravitational field. We firstly investigated the variations of oil content at the water outlet of CES under different working conditions in laboratory experiment. Then dehydration performance of the engineering prototype with two-stage CES were studied in the oilfield test. Oilfield test results showed the CES could effectively demulsify water-oil emulsions with water cut as high as 80%. Electric frequency has more significant influence on dehydration performance than electric voltage. Water content at the oil outlet and oil content at the water outlet of CES could be as low as 3.3% and 302.1 ppm, respectively. The laboratory experiment and oilfield test both have demonstrated good dehydration performance of CES. Results in this study can lay a solid foundation for further optimization and engineering application of compact electrostatic separator.

Analysis of Hydrodynamics of Horizontal Electric Dehydrators for Determining Ways of Intensification of Electrical Crude Oil Desalting and Dehydration

Analysis of Hydrodynamics of Horizontal Electric Dehydrators for Determining Ways of Intensification of Electrical Crude Oil Desalting and Dehydration

Influence of Oil Injection Methods on Hydrodynamics in Electric Dehydrators of Electric Desalting Plants

Influence of Oil Injection Methods on Hydrodynamics in Electric Dehydrators of Electric Desalting Plants

Deformation and breakup of water droplets containing polymer under a DC electric field

AbstractThe deformation and breakup behaviors of droplets containing polymer are investigated by high‐speed photography to reveal the mechanism of electric field collapse when treating the emulsion containing polymer. The results show the electric field collapse process caused by droplet breakup consists of three steps. First, the droplet containing polymer ejects liquid filament under strong electric field. Second, the liquid filament is continuously stretched until it touches positive and negative electrodes. Finally, the severe Joule heating effect appears because the strong electric current flows through the liquid filament. The release of a large amount of heat causes the formation, expansion, and collapse of bubble, resulting in the fracture of liquid filament and the collapse of electric field. The increase of polymer concentration strengthens the Joule heating effect and enlarges the influence scope of bubble expansion and collapse. These findings provide significant guidance for the stable operation of electric dehydrator.

Food Waste Diversion from Landfills: A Cost–Benefit Analysis of Existing Technological Solutions Based on Greenhouse Gas Emissions

Landfill disposals of food result in fugitive emissions of methane—a powerful greenhouse gas (GHG). This desktop study focuses on the cost and GHG emissions associated with food waste diversion from landfills using aerobic digesters with liquid outputs (ADLO). Despite the emerging popularity of ADLO units for food waste disposal, their cost and the GHG emissions associated with their use have not been independently quantified and compared to those of other food waste management options. This study compared landfill disposals, the currently available composting services, electric food dehydrators, and in-sink waste disposal units (garbage grinders). For a food waste production rate of 30 kg d−1, the landfill base case showed the lowest cost at USD 23 week−1. The modeled ADLO cost ranged from USD 20–42 week−1, depending on performance. Dehydrator costs were high at USD 29 week−1, largely due to the high energy intensity of the process. The cost of the current centralized composting was USD 51 week−1. The ADLO option with good performance was estimated to produce 5% of the GHG emissions of a landfill. This study showed that well-performing ADLO technology can be economically competitive with landfills and centralized composting and can markedly reduce GHG emissions.

An Experimental Study on Efficient Demulsification for Produced Emulsion in Alkaline/Surfactant/Polymer Flooding

Abstract Tertiary oil recovery technologies, for example, alkaline/surfactant/polymer (ASP) flooding, can enhance oil recovery as an important oil displacement technology noteworthy in the present oilfields. However, it is the fact that the produced emulsion droplets have strong electronegativity, which will lead to the destabilization of electric field and affect the dehydration effect in the process of electric dehydration. This article innovatively proposed an efficient demulsification scheme, which uses polyaluminum chloride (PAC) as a chemical regulator to control electric field destabilization through the charge neutralization mechanism and then introduces demulsifier to promote oil–water separation. Furthermore, the dehydration temperature, power supply mode, and electric field parameters are optimized so as to achieve superior dehydration effect of ASP flooding produced liquid. The results indicate that PAC as a chemical regulator by exerting charge neutralization and electrostatic adsorption mechanism could reduce the electronegativity of the emulsified system, decrease the peak current of dehydration, shorten the duration of peak current of dehydration, improve the response performance of the electric field, and increase dehydration rate in the ASP flooding dehydration process. When the demulsifier dosage is 100–120 mg/l, using the composite separation process with the dehydration temperature of 45–50 °C for the thermochemical separation stage and 60 °C in the electrochemical dehydration stage and AC–DC composite electric field or pulse electric field can achieve better dehydration effect. The investigations in this study will provide support and basis for the efficient treatment of ASP flooding produced emulsion.

Analysis of Influencing Factors on Performance of Electric Dehydrator and Treatment Measures

Analysis of Influencing Factors on Performance of Electric Dehydrator and Treatment Measures