Wet Natural Gas Research Articles

Simulation of a System to Simultaneously Recover CO2 and Sweet Carbon-Neutral Natural Gas from Wet Natural Gas: A Delve into Process Inputs and Units Performances

The growing need for carbon-neutral energy solutions necessitates the development of efficient systems for carbon dioxide (CO2) recovery and the production of sweet carbon-neutral natural gas (CNNG) from wet natural gas. Despite existing approaches, limitations in process optimization, solvent efficiency, and output purity persist. This study aims to address these gaps by simulating a system for simultaneous recovery of CO2 and CNNG using an integrated three-stage process, modeled in Aspen Plus V8.8. The unique aspect of this work lies in employing the ENRTL-RK base model, coupled with sensitivity analyses to optimize input parameters across 13 interconnected process units, including compressors, heat exchangers, and extraction columns. Key innovations include the novel configuration of units, yielding a recovery efficiency of 95.94% for CNNG and a CO2 purity of 93.185% at optimal conditions, surpassing conventional methods. The performance of the monoethanolamine (MEA) solvent was enhanced by careful adjustment of input parameters, improving its absorption efficiency by 12% compared to standard operational settings. Sensitivity analysis revealed critical parameters such as feed pressure and solvent flow rate as primary drivers for maximizing output efficiency. This study also provides a detailed quantitative assessment of power requirements, with a compressor brake horsepower (BHP) of 18,2605 watts at 110 bar discharge pressure. It addresses the existing research gap by introducing a systematic approach to process optimization, significantly improving the purity and recovery of CNNG and CO2 while minimizing energy consumption. The results not only demonstrate the viability of this process but also provide a foundation for further refinement in sustainable gas processing technologies.

Diffusion in multicomponent mixed solvent electrolyte systems

Thermodynamic ideality is often assumed in diffusion calculation, implying concentrations are assumed equal to the activities with activity coefficients of one. A general set of diffusion flux and molar flux equations are developed, incorporating equilibrium thermodynamic models for non-ideal conditions in well-known non-equilibrium diffusion theory. Derivations are based on the Maxwell-Stefan friction theory with the chemical potential as the driving force. Isothermal and isobaric conditions are assumed, and the theory does not include the Soret coefficient or the Onsager formalism.In this work, Fick's law is derived from the general diffusion theory, also as a function of activity gradients. The results illustrate that concentration cannot just be substituted by activity. Using a similar approach demonstrates that the Nernst-Planck (NP) equation may be derived from the general theory incorporating terms for migration and convection. An extended NP equation is derived including the thermodynamic correction factors (TCF) to account for the non-ideality of the liquid. The derived equation shows the improvement of the self-diffusion terms and friction coefficients in the NP equation and that the TCF enhances the observed effective diffusivities.Examples of TCF are presented using the extended UNIQUAC thermodynamic model. This is done for the CO2-NaOH-monoethyleneglycol-water system, which is typically found in wet natural gas pipeline CO2 corrosion systems. pH-stabilization is classically used in the prevention of corrosion, but the results show that glycol has a noticeable effect of the diffusion on key components in the corrosion mechanism. A TCF of 0.4 to 1.3 may be expected. This indicates that the flux calculation deviates up to 60 % from the real-life scenario if ideality is assumed. The thermodynamic model may therefore improve the diffusion calculations considerably.

Experimental and model research on judging liquid accumulation in pipelines under the action of surfactant

Foam drainage gas extraction is applied in various natural gas extraction scenarios, such as water-bearing gas wells, gas fields with high water content, and wet natural gas pipeline transport, with the goal of enhancing extraction efficiency and lowering production costs. A common issue in foam-carrying liquid gas wells and wet natural gas pipelines is the large errors observed in the prediction model for liquid accumulation onset, derived using ellipsoidal droplets. Additionally, this model is only applicable to a single surfactant type and concentration. To investigate the effects of different types and concentrations of surfactants on the onset of liquid accumulation. This paper re-establishes the critical foam-carrying flow rate model for spherical cap-shaped foam droplets using Newton's laws of motion, through an analysis of their motion state within the air core. Through the critical foam-carrying flow rate test experiments and foam droplet deformation test experiments to obtain critical foam-carrying flow rate model in the surface tension, foam density, Weber number, drag coefficient and other parameters of the change rule and calculation method. The model's validity was further confirmed using field-measured production data from foam-carrying liquid gas wells, demonstrating accurate validation results. Compared to the previous model, this new model treats foam droplets as spherical cap-shape and introduces a dimensionless scaling factor and foaming capacity to quantify the impact of surfactant types and concentrations on foam droplet surface tension and density. This enhances the model's applicability across different types and concentrations of surfactants with greater accuracy. This offers an efficient, precise, and versatile method for predicting liquid accumulation in foam-carrying liquid gas fields, thereby enhancing the efficiency and safety of gas extraction.

ПРИМЕНЕНИЕ МЕТОДА РЕШАЮЩИХ ДЕРЕВЬЕВ ДЛЯ РЕШЕНИЯ ЗАДАЧ АВТОМАТИЧЕСКОГО УЧЕТА РАСХОДА И КОЛИЧЕСТВА ВЛАЖНОГО ГАЗА

This article discusses the application of the decision tree method to solve problems of automatic accounting of the amount of natural gas. This method is used for classification and forecasting tasks. This method is also called a decision rule tree, classification tree, and regression tree. Within the framework of this work, the method of solving trees is used to effectively solve the prob-lem of automatic accounting of the consumption and quantity of wet natural gas. The article considers the algorithm, the process, the structure of the system, the structure, and also analyzes the results of the system.

ANALYSIS OF THE CAUSES OF DAMAGE TO A LONG-OPERATED PIPELINE OF WET HYDROGEN SULFIDE-CONTAINING NATURAL GAS

The results of ultrasonic inspection of discontinuities in the metal of the pipe walls, long time operation under high pressure of wet hydrogen sulfide-containing natural gas, and analysis of the data characterizing them are presented. The criteria for selecting characteristic sections of the pipe with defects and sample cutting for fractographic research are substantiated. Based on the results of the analysis of ultrasound inspection and fractographic investigation, the causes and factors determining the process and mechanisms of sulfide cracking of the pipe walls have been established. The pipeline damage was assessed.

Cu incorporating into OMS-2 lattice creates an efficient Hg0 removal sorbent in natural gas with ambient-temperature H2S/H2O tolerance

Removing mercury in wet natural gas containing acidic components is essential to developing the natural gas purification industry and mitigating corrosion in aluminum heat exchangers. In this work, the Cu-doped manganese oxide octahedral molecular sieve (OMS-2) nanorods were designed for oxidation of Hg0 in wet natural gas. The Hg0 removal efficiency over Cu(0.05)-OMS-2 reached 98.2 % under a high space velocity of 24 × 104 h−1 and a complex atmosphere containing H2O, CO2, and H2S. Surface reactive oxygen species produced by strong electronic interactions owing to Mn-O-Cu hybridization was the main active sites for Hg0 oxidation. The reactive oxygen species on Cu(0.05)-OMS-2 reacted with H2S to form active sulfur species, which could combine with Hg0 to form HgS. Cu(0.05)-OMS-2 exhibited excellent ambient-temperature water resistance, which was attributed to the good redox properties caused by Cu incorporation. This work provided a new strategy for designing efficient sorbents to remove Hg0 from wet natural gas.

Influence of shock wave/boundary layer interaction on condensation flow and energy recovery in supersonic nozzle

Shock train phenomenon occurs when the Mach number increases during the process of energy recovery in the nozzle. However, the reduction of wet natural gas purification efficiency and the increase in energy loss can be caused by shock wave in the supersonic separator. This study focused on the condensation characteristics and pressure energy recovery efficiency under the shock train in the Laval nozzle. A mathematical model was developed for the process of methane-water vapour supersonic condensation and verified by condensation experiments. The results demonstrate that the length of the boundary layer separation interval can be reduced by 0.142 m with a decrease of 0.909 upstream Mach number from 2.367 to 1.458. Multiple nucleation of vapour occurs under the effect of shock train. The droplet growth interval increases from 0 to 0.0859 m and the liquid mass fraction enhances from 0 to 0.12% as the pressure energy recovery efficiency decreasing from 80% to 30%. This indicates that the suitable pressure energy recovery efficiency from 40% to 60% can effectively control the location of the shock train and organize its structure in the nozzle to reduce the separation length of boundary layer and improve the nozzle liquefaction efficiency.

Mechanisms of deep oil–gas accumulation: New insights from the Carboniferous Central Depression, Junggar Basin, China

To investigate the mechanisms of deep oil–gas accumulation in superimposed basins in western China, and identify deep oil–gas reserves in the Junggar Basin, this study examined Carboniferous reservoirs in the Central Depression of the basin. We determined the hydrocarbon physical properties and geochemical characteristics, and controlling factors on hydrocarbon accumulation in the deep part of the Central Depression. We present a geological model of oil–gas accumulation based on analog modeling of reservoir formation. The deep hydrocarbons in the study area are mainly light–medium oil and wet natural gas, which were mainly derived from Permian and Carboniferous source rocks. The hydrocarbon source rocks and their thermal evolution led to hydrocarbon accumulation in the study area. Adjacent source–reservoir rocks on both sides of faults were key to vertical hydrocarbon migration and multi-stage charging. Suitable reservoir–cap rock assemblages were also important for reservoir preservation. The hydrocarbon accumulation model involves a source–reservoir link along faults, late charging, and paleo-uplifts. The reservoir types include those linked to source rocks by large-scale faults and those in paleo-uplifts surrounded by oil-generating depressions, which both have good exploration prospects. This accumulation model may be applicable to deep parts of other superimposed basins.

Study on Pressure Drop Characteristics of a Two-Stage Swirler Separator

Summary The vane swirler separator is widely used in the separation process of wet natural gas owing to a small volume, high efficiency, economy, and environmental protection. In addition to the separation efficiency, the pressure drop is also an important technical and operational index for evaluating the performance of the swirler. In this study, the pressure drop of a swirler vane separator was studied through laboratory experiments and numerical simulations. Through the visualization experimental study of the liquid membrane formation rule and its movement pattern, the reduced gas velocity on the pressure drop was divided into three stages. For a gas superficial velocity less than 5.69 m/s, the effect of gas superficial velocity on the pressure drop was small; for a gas superficial velocity greater than 16.57 m/s, the pressure drop increased significantly with an increase in gas flow rate, and the maximum pressure drop was generated by the two-stage swirler, downstream of which the pressure decreased precipitously. We also observed that when the liquid volume content was less than 3%, the gas superficial velocity was the dominant factor affecting the change in the pressure drop. The average relative error of the pressure drop prediction model based on the conservation of the energy law was 6.16%, which indicated a high calculation accuracy.

Energy separation and condensation effects in pressure energy recovery process of natural gas supersonic dehydration

Pressure energy recovery is one of the main advantages of a supersonic separator. However, the pressure energy recovery process can cause droplet evaporation in the divergent section, which will reduce the liquefaction efficiency of the nozzle. This paper aims to clarify the shock wave/boundary layer interaction and liquefaction efficiency of wet natural gas in the process of pressure energy recovery. A mathematical model of methane-water vapor condensation was established to study the energy separation and condensation characteristics of wet natural gas in the nozzle. The results show that shock wave/boundary layer interaction leads to the energy separation phenomenon. When pressure energy recovery efficiency is reduced from 78.6% to 57.1%, the Mach number and liquid mass fraction at the outlet of the nozzle increase from 0.368 to 0.683 and 0 to 0.73%, respectively. In addition, the counterclockwise vortex region increases, and the energy separation phenomenon becomes more obvious. In actual gas processing, the pressure energy recovery efficiency at the range of 57.1%–64.2% can effectively improve energy recovery efficiency and ensure high liquefaction efficiency of natural gas in the nozzle.

In situ mathematically simulation for CO2 internal corrosion in wet natural gas gathering pipelines system by HYSYS

The rate of corrosion due to the presence of carbon dioxide in a carbon steel pipe is an important design consideration for gathering pipelines, particularly in the transport of wet natural gas. To evaluate the corrosion rate in a gathering pipeline, in situ simulation study using HYSYS program employed to predict CO2 corrosion in natural gas gathering pipelines system. The effects of operational conditions, inhibitors, pipe parameters and flow regime on the CO2 corrosion are studied in this paper. Increasing operating pressure leads to increase the pH and decrease the CO2 corrosion rate when the operating pressure over 10 MPa and the solution contents 0.85kmol/m3 iron carbonate. The CO2 corrosion rate does not always increase with temperature, and which will reach a maximum value at 45 °C. A high gas velocity will lead to a high corrosion rate. Less free water present in pipeline may lead to more serious corrosion than that of a large amount of free water. The corrosion rate may be inhibited by liquid hydrocarbon and glycol, and the glycol is not an economic inhibitor, especially when there is a large amount of free water in pipeline. The large diameter and flat pipe are useful for decreasing CO2 corrosion rate. The shear stress and corrosion rate will increase sharply when the slug flow forms in pipeline. Through comparing the data of simulation with field corrosion rate data, feasibility of this numerical simulation method is proved.

Supersonic refrigeration performances of nozzles and phase transition characteristics of wet natural gas considering shock wave effects

Laval nozzle is the critical part of supersonic separator to provide refrigeration environment. Due to the back pressure at the outlet of supersonic separator in dehydration process, the condensation characteristics of water vapor and the refrigeration performances of the nozzles are affected by the shock wave. Herein, mathematical models for the supersonic condensation and flow of the methane-water two-phase flow model were established, which were verified by the experimental data. The effects of different divergent angles on the refrigeration and condensation behavior in the Laval nozzle were studied considering shock wave. The results show that the refrigeration performance of the nozzle will be worsen under the presence of shock waves. With the divergent angle of the nozzle increased from 2° to 8°, the lowest temperature was decreased from 304.4 K to 291.8 K, the liquid mass fraction at the nozzle outlet was decreased from 0.84% to 0.133%, the maximum droplet radius that can be obtained was reduced from 2.54 × 10−7 m to 1.69 × 10−7 m due to the forward movements of the shock waves. The divergent angle of the nozzle is recommended to be designed to 4°–6° in consideration of the refrigeration performance.

Thermal and Physical Properties of Methane Family Hydrocarbon and Oxygen Combustion Products in State-of-the-Art Arc Steel Furnace

The work deals with the particular combustion characteristics of methane family hydrocarbons (methane, ethane, propane, butane) and wet natural gas with process oxygen at carbon dioxide and water steam dissociation in a state-of-the-art arc steelmaking furnace. An algorithm is developed to calculate chemistry, the amount and concentration of combustion products at carbon dioxide and hydrogen dissociation, their physical and thermophysical parameters; heating power, balance and actual temperature, heat and pyrometric factors are evaluated considering heat transfer by radiation into unbounded medium. Based on the calculation results the recommendations are given for development of cold charge material heating conditions in order to minimize dusting, carbon oxide and hydrogen and charge material loss.

Hydrocarbon simulation behavior of wet natural gas reservoirs

Knowing hydrocarbon dew point conditions in natural gas (HCDP) are becoming widely important in the modern marketing of liquid and gas. Without determination dew point conditions (Pressure & Temperature), the accurate description of phase changes and phase behavior cannot be achieved. Numerous models for only predicting dew point pressure of gas condensate have been proposed and other for wet natural gas reservoirs, but there is no model for predicting both dew point pressure(DPp) and dew point temperature (DPT) for wet natural gas reservoirs. Some of the published models assume knowledge the reservoir fluid composition (requiring laboratory experiments to be performed), while others only require field parameters such as reservoir temperature, stock-tank oil API, and the condensate-gas ratio (CGR). The primary objectives of this paper are to determine dew point temperature (DPT) and dew point pressure (DPp) correlations using a fluid database of nearly fifty-six wet natural gas reservoirs, that is very important for engineers to understand and manag wet natural gas reservoirs. This model was made using multiple least-square nonlinear regression analysis methods to find hydrocarbon dew point conditions (HCDP) as a function of [CGR, Tr, API gravity, γw, γC7+, MWw and C1, C2, CO2, N2 mole %] with a different constant value. Both statistical and graphical accuracy ensures that new models are more accurate in predicting hydrocarbon dew point conditions (HCDP) in comparison with equations of state by using limited data. Finally, thirty-four new separate set of measured data were used in testing models with the excellent agreement as compared with laboratory works.

Study on application of wet gas metering technology in shale gas measurement

The application of wet gas flow meter at shale gas wellhead is of great significance to reduce the investment and operation cost of shale gas extraction. In this paper, the flow conditions at the wellhead of shale gas and the principles of the current wet gas flow meters are briefly analyzed. A wet gas flow meter was tested on the wet gas flow test facility, and its performance of flow rates evaluation is studied, which is helpful to optimize the wet gas metering process design of shale gas wellhead and to improve the wet gas metering technology. This study shows that the measurement principles of the current wet gas flow meters are feasible, however, the calibration by using the wet natural gas at working conditions can help to enhance the meter's measure performance.

ДОСЛІДЖЕННЯ ВПЛИВУ КОНСТРУКТИВНИХ ФАКТОРІВ НА ТЕХНІЧНУ РЕАЛІЗАЦІЮ МЕТОДУ ЕКСПРЕС-КОНТРОЛЮ ТЕПЛОТИ ЗГОРАННЯ ПРИРОДНОГО ГАЗУ

Проведено аналіз відомих нормативних методів і технічних рішень для розрахункового і експериментального методу визначення теплоти згорання природного газу. Обгрунтовано необхідність визначення теплоти згорання вологого природного газу у споживачів за місцем роботи газоспоживного обладнання. Викладено технічне рішення для реалізації запатентованого авторами способу визначення теплоти згорання природного газу прямим методом за температурою згорання газу. Кількісно оцінена зміна відносної похибки визначення теплоти згорання природного газу від вологи газу і вологи повітря для умов реалізації запропонованого способу визначення теплоти згорання для конкретних трьох проб газу з теплотою згорання 7759 ккал/м3, 8145 ккал/м3 та 8538 ккал/м3. Встановлені закономірності зміни відносної похибки визначення теплоти згорання від двох складових вологості. Здійснене моделювання відносної похибки визначення теплоти згорання природного газу одночасно від його вологості і вологості навколишнього повітря. Досліджено вплив конструктивних факторів, які впливають на технічну реалізацію методу експрес-контролю теплоти згорання природного газу. Встановлено наявність суттєвого градієнта температури вздовж поверхні тонкої пластини та набагато менше її значення для грубшої пластини. Досліджені динамічні характеристики нагрівання пластини і термопари при вимірюванні температури полум’я.

Failure analysis of carbon dioxide corrosion through wet natural gas gathering pipelines

The aggressive behavior of carbon dioxide dissolved in water considers as one of basic reasons behind corrosion failure in oil and gas processes. Simulation study using HYSYS program employed to predict CO2 corrosion in natural gas gathering pipelines system. This work examines the effect of operating pressure, temperature, pH solution, pipeline length, flow regime, and pipe inclination on the CO2 corrosion. Based on the simulation results, following highlights were identified: increasing operating pressure results in increases CO2 partial pressure and promotes corrosion rate. Temperature affects formation of protective layer, where maximum CO2 corrosion rate reached 2.96 mm/year at 40°C for this simulation conditions. After 40°C, the protective layer consists and becomes more dense and reduces corrosion rate. In addition, lower pH enhances the solubility of carbonate, reduces participation rate, and enhancing CO2 corrosion. Dissolved CO2 concentration decreases along the pipeline length and the corrosion rate reduces as result. High velocity means efficient mixing which leads to prevent the formation of the protective layer and increases CO2 corrosion. Pipeline inclination affects the velocity of flow where positive elevation change reduces fluid velocity, while minus elevation change promotes fluid velocity. Frequently, these factors depend on each other and sharing the effects on the CO2 corrosion. The prevention of CO2 corrosion in natural gas gathering pipelines starts by understanding the effects of the operation conditions.

Enhancing natural gas dehydration performance using electrospun nanofibrous sol-gel coated mixed matrix membranes

The dehydration process of natural gas was investigated by mixed matrix membranes (MMM), which were fabricated by electrospinning and sol-gel coating methods. Silica and titania nanoparticles (NPs) were incorporated into the polymer matrix via sol-gel method. The fabricated MMMs were characterized by field emission electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Dehydration tests were carried out for wet pure methane and natural gas streams individually. The effects of different process parameters, including feed and sweep gas flow rates, moisture content in the feed, feed pressure and other hydrocarbons in the feed were investigated. The prepared electrospun nanofibrous supports (ESNS) have smaller fiber diameters in comparison to previously reported works, and with regard to the commercially available materials, contribute to higher water vapor permeation. The results showed that by increasing the feed pressure from 2.5 to 15 bar for the membranes without NPs, the permeance of methane and water vapor was decreased by 8.2 and 29%, respectively. It was also observed that the permeance of heavier hydrocarbons in Pebax 1657 membrane is higher than methane, leading to the increase of H2O/CH4 selectivity and the loss of heavier hydrocarbons. Finally, determining the resistances of the support and selective layers based on the existing empirical relations demonstrated that the total resistance to water vapor transmission had decreased by 75.2% using ESNS instead of microporous supports (MPS). In addition, the contribution of support layer resistances was decreased from 67% in MPS membranes to less than 30% in ESNS ones.

Pilot application of a novel Gas–Liquid separator on offshore platforms

Existing devices available on offshore gas/oil platforms are incapable of realizing complete separation of the liquid phase from wet natural gas. This results in eccentric motion of rotors and eventually causes trouble halting of natural-gas compressors. To tackle this problem, use of a novel gas-liquid separator has been reported for offshore oil platform applications. A pilot scale test was performed using the proposed equipment. Results of the test demonstrate that the optimum operating point of the pilot plant corresponds to a flow rate of 90 m3/h (30 °C, 5.0 MPa), and this could be used as a reference for subsequent industrial scale-ups. The results of the pilot test lead to the conclusion that the said novel separator has higher separation efficiency when compared against conventional industrial devices used on oil platforms. Using of the proposed equipment is aimed at alleviating the problem of liquid entrainment of natural gas entering the compressor, increasing compressor service life, and reducing operational and maintenance costs. The proposed study provides a new outlook towards engineering design of offshore-oil-platform equipment of theoretical as well as practical value.

Separation of Methane Emissions From Agricultural and Natural Gas Sources in the Colorado Front Range

AbstractThis proof‐of‐concept study demonstrates that methane (CH4) emissions from natural gas (NG) and agriculture can be disentangled using the concept of excess column observations. A network of cost‐effective sensors measured excess column‐averaged dry‐air mole fractions for CH4 (ΔXCH4), ethane (ΔXC2H6 as NG tracer), and ammonia (ΔXNH3 from agriculture) in the Denver‐Julesburg Basin during March 2015. ΔXCH4 varied up to 17 ppb and was >3 times higher with winds from directions where NG is produced. The ΔXCH4 variance is explained by variations in the C2H6‐NH3 tracer pair, attributing 63 ± 17% to NG, 25 ± 10% to agriculture, and 12 ± 12% to other sources. The ratios ΔXC2H6/ΔXCH4 (16 ± 2%; indicates wet NG) and ΔXNH3/ΔXCH4 (43 ± 12%) were compatible with in situ measured ratios. Excess columns are independent of boundary layer height, characterize gases in the open atmosphere, are inherently calibrated, average over extended spatial scales, and provide a complementary perspective to quantify and attribute CH4 emissions on regional scales.