Oil Gas Separation Research Articles

Design and optimization of a novel porous plate oil–gas separator

In the oil-injection compressor system, it is necessary to separate the lubricating oil by sequentially applying the mechanical separator and the separating filter element, however, the oil–gas separation filter has disadvantages such as short service life, high cost, and great environmental pollution. In this paper, a porous plate separator is proposed to achieve the coalescence of small oil droplets, and then the larger droplets can be removed by mechanical collisions driven by turbulence flow in the separator. This device is designed to be used after the primary separator, in the hope of replacing the separation filter element. The structure of the porous plate oil–gas separator is constructed through the staggered arrangement of two porous plates, and the two-phase flow characteristics in the separator are simulated through the Euler-Lagrangian method with the droplet’s behavior of collision and breakup considered. The hole diameter, hole distance, plate distance, and inlet velocity are the key parameters of the separator, and these parameters are combined through the orthogonal design method to form several different structures and working conditions. The results of range analysis and pressure difference distribution under different layers are analyzed comprehensively, so the best combination is determined in terms of particle size growth rate, oil separation efficiency, and pressure loss. The designed structure is machined, and a test bench is set up, so the performance of the porous plate separator is experimentally tested. It is found that the simulation results are in good agreement with the experimental data, and the best simulated conditions are also verified by the experiment. When the inlet velocity is 0.2 m·s−1, the optimal scheme is suggested as follows: Hole diameter = 1.5 mm; Hole distance = 3 mm; Plate distance = 1 mm; plate layers = 40.

Study on Oil-Gas Separation Characteristics of Gearbox Sealing System of High-Speed Electric Multiple Unit

Based on the discrete phase model (DPM) and droplet-wall collision model, this paper analyzes the oil-gas separation characteristic and sealing performance of a gearbox sealing system. The results show that the airflow drag force and oil droplet inertia force affect the oil-gas separation efficiency of the sealing system. Furthermore, larger oil droplet diameter leads to a higher separation efficiency and lower outlet back pressure reduces the separation efficiency of smaller diameter oil droplet and increases the separation efficiency of larger diameter droplet. For oil droplet with an intermediate diameter, the separation efficiency first decreases and then increases with the reduction in back pressure.

Experimental Validation of the Numerical Model for Oil–Gas Separation

The oil and gas sector is important to the global economy because it covers the exploration, production, processing, transportation, and distribution of oil and natural gas resources. Despite constant innovation and development of technologies to improve efficiency, reduce environmental impact, and optimize operations in the gas and oil industry over the last few decades, there is still room to increase the efficiency of the industry’s equipment in order to reduce its carbon footprint. The separation of gas from oil is a critical stage in the technological production chain, and it is carried out using high-performance multi-phase separators to limit greenhouse gas emissions and have a low impact on the environment. In this study, an improved gas–oil separator configuration was established utilizing CFD techniques. Two separator geometry characteristics were studied. Both cases have the same number of subdomains, two porous media, and four fluid zones, but with a difference in the pitch of the cyclone from the inlet subdomain. The streamlines in a cross-plan of the separator and the distribution of the oil volume fraction from the intake to the outlet were two of the numerical results that were shown as numeric outcomes. The validation of these results was performed using an experimental testing campaign that had the purpose of determining the amount of lubricating oil that is discharged together with the compressed gas at the separator outlet.

Retracted: High Efficiency Compound Vacuum Oil Gas Separation Technology Based on Integrated Oil Filter of Ultra-High Voltage Transformer

Retracted: High Efficiency Compound Vacuum Oil Gas Separation Technology Based on Integrated Oil Filter of Ultra-High Voltage Transformer

Оптимизация процессов разделения в технологии сепарации пластового газа высокого давления

The oil and gas sector is one of the leading branches of industry in our country. Millions of tons of oil and gas are produced every year in the Russian Federation. Part of the extracted natural resources is put on the international market, the rest is processed domestically providing the population with energy and other useful substances: sulfur, gasoline, oils, bitumen, and so on. Oil and gas processing is a complex process that requires a large amount of human, energy and technical resources. In the modern world, there are different types of oil and gas processing equipment: separators, reactors, furnaces, coagulators, distillation columns, etc. Separators are used for the primary separation of the reservoir gas from impurities, which are based on the separation process. The raw material for the separation plants is high-pressure reservoir gas, as well as gas for stabilization and purging of wells that consists of gaseous and liquid hydrocarbons, reservoir water and organosulfur compounds. These plants are designed to separate high-pressure reservoir gas produced at the production site into gas, gas condensate and associated water. Possible options for upgrading the design of an oil and gas separator for deep oil degassing are being explored. A final stage separator of the NGS-II-6-3000-09G2S type used in oil treatment plants was adopted as a basic model. The disadvantages of the separator design are listed. Design solutions have been developed in order to eliminate the identified shortcomings. The scheme of the modernized design of the oil and gas separator is illustrated. A detailed description of the principle of operation of the proposed design is presented. Calculations have been carried out to improve the efficiency of oil-gas separation.

High Efficiency Compound Vacuum Oil Gas Separation Technology Based on Integrated Oil Filter of Ultra-High Voltage Transformer

In order to improve the filtering effect of vacuum oil purifier, the author proposes the research and application of high-efficiency compound vacuum oil-gas separation technology based on electric ultra-high voltage transformer integrated oil purifier. The author studies under the condition of constant oil temperature and flow rate, the effect of vacuum degree on the filtering effect of transformer oil vacuum oil filter. Using the research results, a frequency conversion automatic vacuum oil filter is designed, which makes the processing process have the characteristics of simple operation, high degree of automation, and high work efficiency. The test results show that if the transformer oil processed by the variable frequency automatic vacuum oil purifier is new oil, its water content is less than 45 mg/kg and the gas content is less than 12%; when the breakdown voltage is greater than 25 kV, the transformer oil index can meet the following requirements after the equipment is filtered for one cycle: breakdown voltage ≥75 kV; water content ≤5 mg/kg; and gas content ≤0.1% (volume ratio). After one cycle (after 100 min), the variable frequency automatic (three-stage) vacuum oil filter can greatly shorten the time of transformer oil circulating and filtering. Conclusion. The designed frequency conversion automatic vacuum oil purifier is obviously better than other transformer oil vacuum oil purifiers.

Detection of ultra-low concentration acetylene gas dissolved in oil based on fiber-optic photoacoustic sensing

Dissolved acetylene gas in oil is the characteristic gas to distinguish overheating and discharge faults of transformer. To realize the detection of ultra-low concentration acetylene in transformer oil, a photoacoustic (PA) gas detection system based on ultra-high sensitive fiber-optic acoustic sensing technique was designed. In order to amplify the power of the laser, an Erbium-doped fiber amplifier (EDFA) was utilized, thereby increasing the intensity of the PA excitation signal. A cantilever based fiber-optic acoustic sensor was utilized to detect the generated PA signal. the interference of carbon dioxide and water vapor on the detection of ultra-low concentration acetylene was studied through analyzing the absorption spectrum. By optimizing the laser modulation parameters, the interference of the interfering gases on the acetylene absorption signal is reduced. Experimental results show that the response time of the system is 9 min with the headspace degassing based oil–gas separation method. The ultra-low concentration of dissolved acetylene gas in oil was tested, and the detection limit reached 0.05 μL/L. The technical solution provides a new solution for transformer fault detection.

Effects of the surface roughness on the separation efficiency of oil–gas mixture impingement on the vertical wall

This paper investigated the effect of the surface roughness (0.3 μm, 1.1 μm, 2.5 μm, and 4.5 μm) on the oil–gas separation efficiency. Through spraying the oil–gas mixture onto the vertical wall, the droplets impingement in inertial separators was imitated. The impact separation efficiency on a wall was calculated by comparing the volume of the collected oil flowing down from the wall with the volume of the impinging oil. Experiments were conducted three different impingement conditions. The impinging velocity and droplets size distributions on the impingement surface were characterized by the Malvern particle size analyzer and the particle image velocimetry (PIV) technique, respectively. The droplets impinging velocities varied in the range of 3−5 m/s, and the Sauter mean diameter was observed around 40 μm. The collecting process can be divided into the initial stage and the steady stage according to the film flow state. It was found that the surface roughness has both advantages and disadvantages effect on the film flow. These two opposite effects are of different importance at different roughness levels. Under the studied impingement conditions, the separation efficiency was all above 80%, and the surface of the middle roughness (1.1–2.5 μm) performed better than the smoothest 0.3 μm surface and the roughest 4.5 μm surface.

Development of an Online Detection Setup for Dissolved Gas in Transformer Insulating Oil

The type and concentration of dissolved gases in transformer insulating oil are used to assess transformer conditions. In this paper, an online detection setup for measuring the concentration of multicomponent gases dissolved in transformer insulating oil is developed, which consists of an oil-gas separation system and an optical system for acquiring the transformer status in real time. The oil-gas separation system uses low pressure, constant temperature, and low-frequency stirring as working conditions for degassing large-volume oil samples based on modified headspace degassing. The optical system uses tunable diode laser absorption spectroscopy (TDLAS) to determine the gas concentration. Six target gases (methane, ethylene, ethane, acetylene, carbon monoxide, and carbon dioxide) were detected by three near-infrared lasers (1569, 1684, and 1532 nm). The stability of the optical system was improved by the common optical path formed by time-division multiplexing (TDM) technology. The calibration experiments show that the second harmonics and the concentrations of the six gases are linear. A comparison experiment with gas chromatography (GC) demonstrates that the error of acetylene reaches the nL/L level, while the other gases reach the μL/L level. The data conforms to the power industry testing standards, and the state of the transformer is analyzed by the detected six characteristic gases. The setup provides an effective basis for the online detection of dissolved gas in transformer insulating oil.

Numerical Investigation of Oil Gas Separation with the Use of VOF CFD

In this research paper, a numerical study regarding gas-oil separation is presented. Employing the geometry of a classic separator used by the NRDI for Gas Turbines COMOTI and a Computer-Aided Design (CAD) software, the computational domain was defined. To perform the Computational Fluid Dynamics (CFD) investigation, the mesh was created with the ANSYS Meshing tool, and the ANSYS CFX was employed as a solver. The computational domain was split into 5 subdomains, 3 were fluid and 2 were defined as porous media. The volume porosity, loss model, and permeability were set up. In terms of turbulence flow, the standard k–ε model was adopted. The results of the numerical calculations in terms of oil volume fraction and streamline profiles were used to analyze the separator configuration. The results show that the numerical investigation with the VOF (Volume of Fluid Method) - CFD model is capable of analyzing the performance of a two-phase separator equipped with two demisters-porous media.

Highly Sensitive Optical Fiber Photoacoustic Sensor for In Situ Detection of Dissolved Gas in Oil

A highly sensitive optical fiber photoacoustic (PA) sensor was proposed and demonstrated for in situ detection of dissolved gas in oil. Two optical fibers were used for the transmission of pump light and probe light, respectively. The miniature detection module integrated by optical fiber sensor and oil–gas separation membrane made it passive and anti-electromagnetic interference. The dissolved gas in oil passed through the organic membrane into the micro-chamber of the PA sensor. The PA signal generated by the gas absorption of laser energy was detected by a Fabry–Perot interferometric cantilever. To reduce the equilibrium time of oil–gas separation and improve the PA response, structural parameters of the sensor were optimized. The experimental results showed that the temperature had an influence on the response time and PA response. The response time was ~1.8 h at 50 °C. To realize temperature compensation, the temperature was measured simultaneously by averaging the measured Fabry–Perot cavity length. In addition, the detection limit of dissolved acetylene (C2H2) gas reached $0.5~\mu \text{L}$ /L. Since oil pumping was not required and the oil did not contact with the ambient air, the oil was not polluted and consumed to achieve in situ measurement.

Numerical Simulation Analysis of Main Structural Parameters of Hydrocyclones on Oil-Gas Separation Effect

Gas pollution in marine lubricating oil systems is harmful to the normal operation of a ship, and is one of the main reasons for the decline of the performance of lubricating oil. In this research, a classic 75 mm hydrocyclone was selected as the oil–gas separation device. A hydrocyclone is a device that uses the density difference of the two-phase flow to separate the dispersed phase in the centrifugal force field. Compared with ordinary active oil–gas separators, hydrocyclones do not require additional power devices. After establishing the physical model of the hydrocyclone, the distribution characteristics of the flow field and oil–gas two-phase flow separation performance of the hydrocyclone were studied using computational fluid dynamics (CFD) technology. The influence of vortex finder diameter, vortex finder length, spigot diameter, cylindrical-part length, and cone angle on the oil–gas separation performance of the hydrocyclone were investigated. It was found that the vortex finder diameter and the spigot diameter have a significant influence on the oil–gas separation performance, whereas the vortex finder length, the cylindrical-part length, and the cone angle have little influence on its performance. Increasing the vortex finder diameter and reducing the spigot diameter can improve the gas separation efficiency. However, the liquid outflow from the vortex finder increases, which causes the liquid loss rate to increase. The presented research could lay a foundation for the optimal design of a hydrocyclone used for oil–gas separation of a marine lubricating oil system.

Integration of alarm design in fault detection and diagnosis through alarm-range normalization

Alarm systems designed according to engineering and safety considerations provide the primary source of information for operators when it comes to abnormal situations. Still, alarm systems have rarely been exploited for fault detection and diagnosis. Recent work has demonstrated the benefits of alarm logs for fault detection and diagnosis. However, alarm settings conceived during the alarm design stage can also be integrated into fault detection and diagnosis methods. This paper suggests the use of those alarm settings in the preprocessing of the process measurements, proposing a normalization based on the alarm thresholds of each process variable. Normalization is needed to render process measurements dimensionless for multivariate analysis. While common normalization approaches such as standardization depend on the historical process measurements available, the proposed alarm-range normalization is based on acceptable variations of the process measurements. An industrial case study of an offshore oil gas separation plant is used to demonstrate that the alarm-range normalization improves the robustness of popular methods for fault detection, fault isolation, and fault identification.

Development of multi‐parameter online monitoring equipment for EHV transformer bushing

To diagnose the running state of bushing and avoid serious power grid accidents, online multi-parameter monitoring equipment for dissolved hydrogen, oil pressure and temperature in bushing oil was developed. The equipment includes three units: signal acquisition, control cabinet and data analysis. A new hydrogen sensor without oil–gas separation membrane and based on palladium alloy film technology was developed. A three-in-one sensor for hydrogen, oil temperature and pressure monitoring has been developed, which has the advantages of miniaturisation, lightweight and easy installation. Test results show the hydrogen measurement range of the sensor is 0–5000 ppm, and the accuracy can reach 10% or 15 ppm (with larger values). The pressure measurement range is 0–1.0 MPa, the resolution is 0.1 kPa, and the accuracy can reach 0.25 grade. The temperature measurement range is −40 to 105°C, and the accuracy is ±1°C. The measurement performance of the device fully meets the requirement of online monitoring of transformer bushing. The equipment has been put into operation in a 330 kV substation, which can monitor the bushing status online and help eliminate the early latent fault of bushing in the weak budding state.

Effect of pre-wetting on the wettability of laser ablated Al superhydrophobic/superhydrophilic surface

A regionally controllable super hydrophobic/super hydrophilic mixed surface was prepared by laser ablation, and the effects of pre-wetting on the surface wettability of samples under water and oil were studied, as well as the stability of the surface wettability of samples. The results show that pre-wetting can change the oil contact angle underwater and water contact angle under-oil on the sample surface, and also change the behavior of bubbles on the surface. After the samples were soaked in water, heated or exposed to air, the super hydrophilic surface showed wettability transformation while the super hydrophobic surface was relatively stable. The sample can maintain long-term stability sealed dry preservation at room temperature. The results are of great significance for oil-water separation, oil-gas separation and bubble control in aqueous media.

Effect of seal clearance on the separation performance for a gearbox sealing system of a high-speed electric multiple unit

Seal characteristic is based on the oil-gas separation performance of the gearbox sealing system of a high-speed electric multiple unit. A model of the gearbox sealing system is established to study the effect of seal clearance on separation performance, based on discrete phase method and droplet-wall collision models. The results show that the airflow drag force and oil droplet inertia force affect the locus of the droplet motion and the oil-gas separation efficiency of the sealing system. However, mass inertia force is the major influencing factor while acceleration inertia force and airflow drag force are secondary factors. The separation efficiency of small oil droplet (diameter 1 µm) decreases as the axial clearance width increases, while the separation efficiency of larger oil droplet (diameter 5 µm) remains unchanged. However, the separation efficiency of intermediate droplet (diameter 2–4 µm) decreases and then increases. Meanwhile, larger axial clearance height difference and radial tooth relative meshing ratio lead to higher separation efficiency. The separation efficiency decreases with increasing radial tooth angle, reaches a minimum at 80°, and then increases with further increase in tooth angle. Thus, the seal clearance has a slight effect on the oil-gas separation efficiency of oil droplet of 5 µm.

STUDYING GAS SEPARATION AT THE INLET OF THE OIL WELL BOTTOM PUMP

The paper describes a measuring method for gas/oil ratio with a mobile setup by means of sending the free gas from annular space of a well directly to the meter, bypassing the oil-gas separation tank. Such arrangement allows reducing separator loads for gaseous phase and increasing the accuracy of measurement of both oil and gas. To assess the amount of gas being separated at pump suction, experiments were conducted on a number of fields being developed by Lukoil-Komi LLC; the experiments aimed to measure the gas coming from the annular space bypassing the separator. An empirical formula has been obtained allowing calculating the gas separation coefficient at suction of calculation at bottom pump suction depending on well oil production and making it possible to predict an amount of gas taken out of the annular space of the well during the metering.

Direct detection of acetylene dissolved in transformer oil using spectral absorption

Dissolved gas analysis (DGA) is an effective method to indicate the health status of power transformers as miscellaneous dissolved gases are often related to the degradation of insulation materials and inner electrical faults. To realize real-time and accurate measurement of dissolved gas, direct infrared spectral absorption focusing on acetylene detection without an oil-gas separation process is proposed in this study. Based on Fourier transform infrared spectroscopy (FTIR), the infrared light transmission of transformer oil is explored, and spectral absorption parameter of acetylene in gas state and oil phase is compared and analyzed. In the laboratory, the sensitivity of direct acetylene dissolved in oil is tested and enhanced. It is confirmed that the transformer oil can transmit the infrared light, locating in the near infrared spectrum of 0.800–1.687 μm and 1.770–2.261 μm. It is also proved that the direct infrared absorption method can detect acetylene dissolved in oil at the central wavelength of 1.534 μm, laying the basis for new type of DGA technique without oil-gas separation.

Sustainable Solution for Crude Oil and Natural Gas Separation using Concentrated Solar Power Technology

In today’s scenario to combat with climate change effects, there are a lot of reasons why we all should use renewable energy sources instead of fossil fuels. Solar energy is one of the best options based on features like good for the environment, independent of electricity prices, underutilized land, grid security, sustainable growth, etc. This concept paper is oriented primarily focused on the use of Solar Energy for the crude oil heating purpose besides other many prospective industrial applications to reduce cost, carbon footprint and moving towards a sustainable and ecologically friendly Oil & Gas Industry. Concentrated Solar Power technology based prototype system is proposed to substitute the presently used system based on natural gas burning method. The hybrid system which utilizes the solar energy in the oil and gas industry would strengthen the overall field working conditions, safety measures and environmental ecology. 40% reduction on natural gas with this hybrid system is estimated. A positive implication for an environment, working conditions and safety precautions is the additive advantage. There could also decrease air venting of CO2, CH4 and N2O by an average of 30-35%.

Photonic crystal fiber modal interferometer with Pd/WO3 coating for real-time monitoring of dissolved hydrogen concentration in transformer oil.

A highly-sensitive and temperature-robust photonic crystal fiber (PCF) modal interferometer coated with Pd/WO3 film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. The sensor probe was fabricated by splicing two segments of a single mode fiber (SMF) with both ends of the PCF. Since the collapse of air holes in the PCF in the interfaces between SMF and PCF, a SMF-PCF-SMF interferometer structure was formed. The Pd/WO3 film was fabricated by sol-gel method and coated on the surface of the PCF by dip-coating method. When the Pd/WO3 film is exposed to hydrogen, both the length and cladding refractive index of the PCF would be changed, resulting in the resonant wavelength shift of the interferometer. Experimental results showed that the hydrogen measurement sensitivity of the proposed sensor can reach 0.109 pm/(μl/l) in the transformer oil, with the measurement range of 0-10 000 μl/l and response time less than 33 min. Besides, the proposed sensor was temperature-insensitive without any compensation process, easy to fabricate without any tapering, polishing, or etching process, low cost and quickly response without any oil-gas separation device. All these performances satisfy the actual need of real-time monitoring of dissolved hydrogen concentration in the transformer oil.