Mixture Of Methane Research Articles

Stability Indicating Method Development and Validation for the Simultaneous Estimation of Diacerin, Glucosamine sulphate and Methyl sulfonyl methane by RP-HPLC

Treatment for osteoarthritis includes a mixture of Diacerin (DIA), Glucosamine sulphate (GLU), and Methyl sulfonyl methane (MSM). Methyl sulfonyl methane functions as a dietary supplement, whereas Diacerin and Glucosamine sulphate stimulate proteoglycan synthesis. The simultaneous quantification of DIA, GLU, and MSM in pharmaceutical dosage forms has been developed using the RP-HPLC method. With a flow rate of 0.9 mL/min, chromatography was performed on an Agilent C18 150x 4.6, 5.0 mm column. pH 3.0 0.1 percent orthophosphoric acid buffer and 60:40 (percent v/v) acetonitrile made up the mobile phase. 2.233, 2.823, and 3.286 minutes were found to be the retention times for DIA, GLU, and MSM, respectively. In the concentration ranges of 2.5-15 g/mL (R2 = 0.999) for DIA, 37.5-225 g/mL (R2 = 0.999) for GLU, and 12.5-75 g/mL (R2 = 0.999) for MSM, the approach follows Beer's law. Diacerin's LOD and LOQ were discovered to be 0.05 g/mL and 0.14 g/mL, Glucosamine sulphate's LOD and LOQ were 0.90 g/mL and 2.73 g/mL, and Methyl sulfonyl methane's LOD and LOQ were 0.88 g/mL and 2.67 g/mL, respectively. Recovery studies in the dose form at three concentration levels were used to assess the accuracy of the established approach. The mean percent recovery for DIA, GLU, and MSM was determined to be 99.62 percent, 99.62 percent, and 99.94 percent, respectively. The approach was used to calculate the dosage of Orcerin GM tablets. As per ICH requirements, the devised approach has been statistically validated. As a result, the chromatographic method developed for the estimation has been described as rapid, simple, precise, accurate, robust, and reliable, and it can be used for routine analysis in research institutions, quality control departments in industries, approved testing laboratories, biopharmaceutics and bioequivalence studies, and clinical pharmacokinetic studies.

Suitable Binary and Ternary Thermodynamic Conditions for Hydrate Mixtures of CH4, CO2, and C3H8 for Gas Hydrate-Based Applications.

The selection of suitable hydrate formers and their respective gas composition for high hydrate formation, driving force is critical to achieve high water recovery and metal removal efficiency in the hydrate-based desalination process. This study presents a feasibility analysis on the possible driving force and subcooling temperatures for the binary and ternary mixtures of methane, carbon dioxide, and propane for hydrates-based desalination process. The driving force and subcooling for the gas systems was evaluated by predicting their hydrate formation phase boundary conditions in 2 wt % NaCl systems at pressure ranges from 2.0–4.0 MPa and temperatures of 1–4 °C using modified Peng–Robinson equation of state in the PVTSim software package. The results suggest that the driving force of CH4 + C3H8 and CO2 + C3H8 binary systems are similar to their ternary systems. Thus, the use of binary systems is preferable and simpler than the ternary systems. For binary gas composition, CO2 + C3H8 (70:30) exhibited a higher subcooling temperature of 8.07 °C and driving force of 1.49 MPa in the presence of 2 wt % aqueous solution. In the case of the ternary system, CH4–C3H8–CO2 gas composition of 10:80:10 provided a good subcooling temperature of 12.86 °C and driving force of 1.657 MPa for hydrate formation. The results favor CO2–C3H8 as a preferred hydrate former for hydrate-based desalination. This is attributed to the formation of sII structure and it constitutes 136 water molecules which signifies a huge potential of producing more quantities of treated water.

Reaction Mechanisms Testing with Spatial and Thermal Resolutions of Methane/Air Flames

Spatial and thermal dispersals of hydroxyl (OH), formaldehyde (CH2O), and other minor species have been acquired using various detail reaction mechanisms in the weak flame of stoichiometric methane and air mixture at ambient pressure. The weak flame was simulated inside a microflowcombustor with a prescribed temperature profile which releases a very small amount of heat. A wide reaction zone (~ 1 cm) was observed for methane and air flames compared to normal/conventional flames. Detailed oxidation analysis was carried out based on the normal and weak flames simulations. The computational flame structure was assessed with the experimentalresults available in the existing literature. Numerical modeling under the experimental conditions with various detail mechanism predicts a similar wide reaction zone. However, the species production and consumption temperatures were observed to vary for the different mechanisms used in present studies. The GRI mech 3.0 shows a typical two-peak heat release rate profile. The initial breakdown of fuel is vital for such scatter. The production of OH radical governs the initial breakdown of fuel at the intermediate temperatures. The present investigation is pretty useful in understanding the chemistry of intermediate species for different fuel-air mixtures specially at intermediate temperatures 800–1200 K.

Investigation on the influence of modified zeolite molecular sieve on the hydrocarbon adsorbent and adsorption performance during cold-start conditions based on Monte Carlo simulation and grey relational analysis

To discover adsorbents with promising adsorption capability for hydrocarbon catcher, this study numerically investigated the adsorption process of modified MOR, MFI, and CON zeolites utilized in hydrocarbon catcher of hydrocarbon (HC) molecules for hydrocarbon emission control during cold-start. Ethylene (C2H4) and benzene (C6H6) were used as probe molecules in the single-component adsorption simulation. The mixture of methane (CH4), C2H4, propylene (C3H6), propane (C3H8), water (H2O) and C6H6 was used as adsorbate in the multicomponent adsorption simulation. The Grand Canonical Monte Carlo (MC) method was used in the adsorption simulation. Grey Relational Analysis (GRA) method was used to determine the influence degree of zeolite molecular sieve type and environmental conditions on the adsorption capacity of hydrocarbons. The adsorption isotherms of hydrocarbon single component and multicomponent molecules on different silicon-aluminum (Si/Al) ratios and different ion exchange zeolites were studied at various low temperatures and pressures. Results of adsorption simulation present that the best adsorption effect on C2H4 was obtained for the magnesium ion (Mg2+) modified MFI molecular sieve at a Si/Al ratio of 3. The adsorption of C6H6 was better for the Na+ modified molecular sieve at Si/Al ratios of 15 and 7. Mg2+ modified MOR molecular sieve can be given priority when the overall control of hydrocarbon mixture content is required, which has adsorption for all kinds of hydrocarbon molecules and more uniform adsorption performance. The calcium ion (Ca2+) modified MFI molecular sieve is suitable for the condition when exhaust gas contains more C3H6, while Mg2+ modified MFI molecular sieve can be used when there are more C3H8. In GRA, the factors with the greatest influence on the adsorption of the C2H4 component are the type of molecular sieve and the porosity. The most important factors on the adsorption of the C6H6 component are the molecular sieve type and temperature, followed by the porosity. In the adsorption of multicomponent hydrocarbons, porosity has the greatest effect on the adsorption amount, followed by molecular sieve type and Si/Al ratio. In addition, the total adsorption of hydrocarbon molecules will be increased with the Si/Al ratio of the molecular sieve.

A comparative study for H[formula omitted]–CH[formula omitted] mixture wettability in sandstone porous rocks relevant to underground hydrogen storage

Characterizing the wettability of hydrogen (H2)–methane (CH4) mixtures in subsurface reservoirs is the first step towards understanding containment and transport properties for underground hydrogen storage (UHS). In this study, we investigate the static contact angles of H2–CH4 mixtures, in contact with brine and Bentheimer sandstone rock using a captive-bubble cell device at different pressures, temperatures and brine salinity values. It is found that, under the studied conditions, H2 and CH4 show comparable wettability behaviour with contact angles ranging between [25°–45°]; and consequently their mixtures behave similar to the pure gas systems, independent of composition, pressure, temperature and salinity. For the system at rest, the acting buoyancy and surface forces allow for theoretical sensitivity analysis for the captive-bubble cell approach to characterize the wettability. Moreover, it is theoretically validated that under similar Bond numbers and similar bubble sizes, the contact angles of H2 and CH4 bubbles and their mixtures are indeed comparable. Consequently, in large-scale subsurface storage systems where buoyancy and capillary are the main acting forces, H2, CH4 and their mixtures will have similar wettability characteristics.

Distribution and Combustion of Hydrogen and Methane Mixtures with Air in a Container with Baffles: An Investigation

Distribution and Combustion of Hydrogen and Methane Mixtures with Air in a Container with Baffles: An Investigation

Ozone production in a dielectric barrier discharge in air- and oxygen–methane mixtures. Experiment and modeling

The effect of methane on ozone production in a dielectric barrier discharge (DBD) was studied in mixtures of CH4 with synthesized air and oxygen. It was found that addition of CH4 significantly reduced the number density of ozone other conditions being equal. A DBD model was developed that takes into account the spatial structure of microdischarges and the fact that near the electrodes their filaments transform into surface discharges, where most of ozone is produced. In addition, in air and air–CH4 mixtures the successive microdischarges were considered to occur not randomly in space, but at the same positions on the electrodes or moving with the flow occurring in the same volumes. The measured values of ozone number density downstream of the DBD were compared with simulation results, obtained with this novel DBD model. A good agreement between experiment and calculations was observed.

Valorization of industrial waste lignin via pyrolysis in the presence of additives: Formation, characterization, and application of fuel valued bio-oil and activated char

The annual production of over 50 million tonnes of industrial waste kraft lignin and scant utilization invites environmental concern. To explore the potential of simultaneously produced bio-oil and modified char (Activated char), lignin from industrial effluents was subjected to pyrolytic degradation at 380 °C using various additives, viz., H3BO3, ZnCl2, and KOH yielding encouraging quantities of bio-oils besides substantial quantities of char. Quantitative and qualitative analyses of gaseous products (by GC-TCD) indicated a mixture of CO, CO2, H2, and methane, with some variation in volumetric composition suggesting potential for gaseous fuel/syngas. Gaseous products obtained in the presence of H3BO3 have the highest methane percentage. The bio-oils obtained in the presence of H3BO3, ZnCl2, KOH, and only pure lignin under otherwise similar conditions were respectively 37%, 21%, 27%, and 11 wt%. In all cases, mainly bio-oils contain phenols, cyclic esters, and carboxylic acids, as indicated by GC-MS analysis. Elemental (C, H, O) Analyses of bio-oils obtained in the presence of (H3BO3, ZnCl2, and KOH) indicated decreasing oxygen content compared to original lignin, suggesting their prima facie potential to lead to fuel additives/supplements. Similarly, the Char obtained in the presence of H3BO3, ZnCl2, KOH, and only pure lignin were respectively, 40%, 53%, 48%, and 33 wt% with a high calorific value. Char obtained from KOH application demonstrated good uptake of Carbofuran (pesticide) from the aqueous solution. Less modified, cost-effective activated char was characterized using FTIR, TG-DTA, XRD, SEM, and BET-BJH, indicating 188.798 m2/g; this explores the role of KOH to form a microporous structure. Pseudo-second-order kinetics explain chemisorption to be dominant in the adsorption process. Thus, pyrolysis at selected temperatures/additives/and further treatments provides a much better way to utilize industrial waste lignin.

Effect of pore structure on competitive sorption and diffusion of mixed methane and carbon dioxide in anthracite, South Qinshui Basin, China

A deep understanding of the competitive adsorption and diffusion of methane (CH4) and carbon dioxide (CO2) in coal is significant for implementing the CO2-ECBM project. For three high-rank coal samples, industrial analysis, coal maceral, and vitrinite reflectance (RO) determination, mercury injection test, and low-temperature nitrogen/carbon dioxide specific surface test were carried out, and the composition and pore structure of coal samples were studied systematically. Meanwhile, through the three mixed gases (75%CH4 + 25%CO2, 50%CH4 + 50%CO2, 25%CH4 + 75%CO2) adsorption and desorption test, the absolute adsorption amount, free phase and adsorption phase of CH4 and CO2 under different equilibrium pressures, and the equivalent diffusion coefficients of gas migration in the process of adsorption/desorption equilibrium were calculated. Finally, the relationship among the coal composition, pore structure, and the competitive adsorption and diffusion characteristics of methane and carbon dioxide mixture in coal were studied. The results show that: (1) the composition of coal has an important influence on the development of coal pore structure and the adsorption and transport of gas in coal. Supermicropore (<2 nm in size) is the prominent adsorption place. Furthermore, its development, which essentially determines the adsorption capacity of coal samples, is positively correlated with fixed carbon content, vitrinite content, and vitrinite reflectance. (2) When the pores >100 nm in size relatively developed, the coal samples have higher porosity, lower micropore diffusion, and a smaller desorption hysteresis index. Because the pore's connectivity is limit, its content has no apparent correlation with the permeability of coal samples and most of the adsorption and diffusion parameters. (3) The desorption hysteresis is mainly caused by the opposite migration direction of gas in the process of adsorption and desorption and the resulting dislocation of coal matrix swelling and shrinkage. The competitive adsorption of CH4 or CO2 and their separation index (SCO2/CH4) in coal samples decreases with the increase of adsorption equilibrium pressure. Also, the desorption process often shows a higher SCO2/CH4 value than that of the adsorption process. (4) During the adsorption process, the equivalent macro-diffusivities of the coal sample decrease as a power function with increasing pressure and increase with the carbon dioxide content increasing in the mixed gas. However, the equivalent micro-diffusivities change little with the different CH4 and CO2 mixtures migration in different coal samples. The equivalent diffusion coefficient of coal is positively correlated with macropore, mesopore, transitional and micropore content in coal samples.

Experimental investigation and new correlation for the bubble departure diameter of methane and ethane binary mixtures during nucleate pool boiling

Methane and ethane are the main components of liquefied natural gas (LNG) and mixed-refrigerant liquefaction cycles. The pool boiling characteristics and bubble dynamic parameters of methane/ethane mixtures are important for the design and optimization of LNG systems. In this study, visual experiments were carried out to investigate the pool boiling of methane, ethane and their mixtures on a horizontal flat surface. Heat transfer characteristics and bubble departure diameters were acquired at 0.3 MPa for different concentrations of the mixtures. The bubble departure diameter increases with the increase in superheat temperature and dimensionless Jacob number for all concentrations of the mixture. The non-linear variation with concentrations of the bubble departure diameter can be observed due to the effects of mixtures. The bubble departure diameters for mixtures were predicted by twelve existing correlations, with Cole's correlation having the lowest mean absolute relative deviation (MARD) of 46.28%, with only 38.78% points within ±30% deviation. Therefore, a new model for mixtures was developed based on force equilibrium analysis in this study. Marangoni force is taken into account in the proposed model, as well as the effects of mass transfer on the bubble growth rate in mixtures. The MARD of the new model is 18.78%, which is better than all the twelve existing correlations.

Hydrogen production from methane and carbon dioxide mixture using all-solid-state electrochemical cell based on a proton-conducting membrane and redox-robust composite electrodes

In recent years, interest in hydrogen as a fuel has sharply increased in the field of alternative and green energy due to its high energy capability and zero-emission behaviour. As a result, research in the development of new highly efficient methods for producing high-purity hydrogen is relevant. This paper presents, for the first time, the test results of an electrochemical cell with a proton-conducting La0.9Sr0.1ScO3–δ electrolyte and symmetrical Sr1.95Fe1.4Ni0.1Mo0.5O6–δ + La0.9Sr0.1Sc0.9Co0.1O3–δ electrodes as a hybrid setup for electricity generation in proton ceramic fuel cell mode, for hydrogen separation from H2 + Ar mixture and the production of high-purity hydrogen from methane with simultaneous CO2 utilization. It was found that this electrochemical cell generates high flow rates of hydrogen during its separation through a proton-conducting membrane from H2 + Ar mixture, about 500 cm3 h−1 cm−2 at a current density of 0.6 A cm−2 as well as about 370 cm3 h−1 cm−2 at a current density of 0.5 A cm−2 from CH4 + CO2 mixture at 800 °C which shows that these cells are promising for hydrogen production.

Comparative study on flame instability and combustion characteristics of CH4/O2/CO2 and CH4/O2/N2 mixtures

To investigate flame instabilities and combustion characteristics of oxygen-enriched methane in a closed chamber, a series of combustion experiments on the CH4/O2/CO2 and CH4/O2/N2 mixtures were conducted at the initial temperature and pressure of 301 ± 2 K and 1.0 atm. The results show that the distorted tulip flames and corrugated flames, which can be differentiated by a 2D plane of firstly wall-touching pressure (Pwall/P0) versus flame position (Ztipwall/L), are for the first time observed in the oxygen-enriched methane mixtures. Particularly, the corrugated flames can emerge by increasing the reactivity of CH4/O2/N2 mixtures. There are distinct flame instabilities between the CO2/N2 diluents. Specifically, the CH4/O2/CO2 mixtures always show stronger Thermal-Diffusive instability whereas the CH4/O2/N2 mixtures always exert stronger Darrieus-Landau instability. There is a linearly positive correlation between the Darrieus-Landau instability and oxygen enrichment ratio for both mixtures. In contrast, the oxygen enrichment ratio plays positive (N2 dilution) and negative (CO2 dilution) role for the Thermal-Diffusive instability. A linear prediction between the maximum combustion pressures and Sl·E/lfg is proposed by considering the Darrieus-Landau instability. However, the Rayleigh-Taylor instability, as an additional mechanism for flame distortion, makes the linearity less accurate. As the oxygen enrichment ratio is further increased, the Richtmyer-Meshkov instability instead of the Rayleigh-Taylor instability plays a role in converting distorted tulip flames to corrugated flames, and could revalidate this linear prediction.

Numerical Simulation Analysis of Heating Effect of Downhole Methane Catalytic Combustion Heater under High Pressure

The hot exhaust gas generated by a downhole combustion heater directly heats the formation, which can avoid the heat loss caused by the injection of high-temperature fluid on the ground. However, if the temperature of the exhaust gas is too high, it may lead to the carbonization of organic matter in the formation, which is not conducive to oil production. This paper proposes the use of low-temperature catalytic combustion of a mixture of methane and air to produce a suitable exhaust gas temperature. The simulation studies the influence of different parameters on the catalytic combustion characteristics of methane and the influence of downhole high-pressure conditions. The results show that under high-pressure conditions, using a smaller concentration of methane (4%) for catalytic combustion can obtain a higher conversion efficiency (88.75%), and the exhaust temperature is 1097 K. It is found that the high-pressure conditions in the well can promote the catalytic combustion process of the heater, which proves the feasibility of the downhole combustion heater for in situ heating of unconventional oil and gas reservoirs.

Effect of nitrogen on deflagration characteristics of hydrogen / methane mixture

In order to study the influence of nitrogen on the deflagration characteristics of premixed hydrogen/methane, the explosion parameters of premixed hydrogen/methane within various volume ratios and different dilution ratios were studied by using a spherical flame method at room temperature and pressure. The results are as follows: The addition of nitrogen makes the upper limit of explosion of hydrogen/methane premixed gas drop, and the lower limit rises. For explosion hazard (F-number), hydrogen/methane premixed fuel with a hydrogen addition ratio of 10% has the lowest risk, and nitrogen has a greater impact on the dangerous degree of hydrogen and methane premixed gas whose hydrogen addition ratio does not exceed 30%. In terms of flame structure, the spherical flame was affected by buoyancy instability as the percentage of nitrogen dilution increased, but the buoyancy instability gradually decreased as the percentage of hydrogen addition increased. The addition of diluent gas reduces the spreading speed of the stretching flame and reduces the stretching rate in the initial stage of flame development. The laminar flame propagation velocity calculated by the experiment in this paper is consistent with the laminar flow velocity of the hydrogen/methane premixed gas calculated by GRI Mech 3.0. Considering the explosion parameters such as flammability limit, laminar combustion rate and deflagration index, when hydrogen is added to 70%, it is the turning point of hydrogen/methane premixed fuel.

Use of Boundary-Driven Nonequilibrium Molecular Dynamics for Determining Transport Diffusivities of Multicomponent Mixtures in Nanoporous Materials.

The boundary-driven molecular modeling strategy to evaluate mass transport coefficients of fluids in nanoconfined media is revisited and expanded to multicomponent mixtures. The method requires setting up a simulation with bulk fluid reservoirs upstream and downstream of a porous media. A fluid flow is induced by applying an external force at the periodic boundary between the upstream and downstream reservoirs. The relationship between the resulting flow and the density gradient of the adsorbed fluid at the entrance/exit of the porous media provides for a direct path for the calculation of the transport diffusivities. It is shown how the transport diffusivities found this way relate to the collective, Onsager, and self-diffusion coefficients, typically used in other contexts to describe fluid transport in porous media. Examples are provided by calculating the diffusion coefficients of a Lennard-Jones (LJ) fluid and mixtures of differently sized LJ particles in slit pores, a realistic model of methane in carbon-based slit pores, and binary mixtures of methane with hypothetical counterparts having different attractions to the solid. The method is seen to be robust and particularly suited for the study of study of transport of dense fluids and liquids in nanoconfined media.

Separation of He/N2/CH4 ternary mixtures by a triple‐reflux pressure swing adsorption process

AbstractConventional pressure swing adsorption (PSA) processes can only produce one high purity product in a single stage, whereas the state‐of‐art dual‐reflux PSA (DR‐PSA) can produce two high purity products simultaneously. However, multicomponent gas separation is often required in the industry, targeting at recovering several valued products at the same time. In this study, we propose a novel adsorption process, namely triple‐reflux PSA (TR‐PSA), to separate three components simultaneously. A middle product outlet and a middle reflux stream were introduced to the adsorption columns of a conventional DR‐PSA process to separate ternary mixtures of nitrogen, methane, and helium. Nonisothermal dynamic models were built to investigate the impacts of operating parameters particularly the location of the middle reflux/product stream and the middle reflux flow rates. Results showed that the TR‐PSA process successfully separated ternary mixtures obtaining three enriched products simultaneously in a single stage, yielding a separation performance comparable to that of the double‐stage DR‐PSA with significantly lower capital and energy cost.

INFLUENCE OF DIGESTION TEMPERATURE ON BIOGAS PRODUCTION FROM DISCARDED CASSAVA ( manihot esculenta) PEELS

Anaerobic digestion is an established technology for treating different kinds of wastes and to simultaneously produce biogas (mixture of methane and carbon dioxide), which is useful and renewable energy source. In this work, the influence of temperature on the biogas production from cassava peels was studied in batch type anaerobic digesters of volume 500 ml at digestion temperatures of 35±5 0C, 45±5 0C and 55±5 0C for a retention period of 30 days. The quantity of the biogas produced daily were measured with a pressure gauge for the 30 days retention period and converted to volumetric gas yield. It was observed that the cumulative biogas yield increases by 25 % when the digestion temperature was raised from the mesophilic temperature range to thermophilic temperature range. The highest cumulative biogas yield of 289.33×10-5 m 3/kg-TS was obtained with the highest digestion temperature of 55±5 0C. It is therefore concluded that biogas production increases with the increase in digestion temperature and it is recommended that anaerobic digestion should be carried out at the thermophilic temperature range for better gas yield.

Municipal Solid Waste as an Alternate Source of Energy: A Review

Municipal solid waste (MSW) is a big environmental challenge. However; it is a potential source of recycling materials, heat and energy. In developed countries this waste is used as resource to produce energy and compost; whereas in developing countries like India, collection, transportation and disposal of MSW are a big task. Wastes to energy technologies (WTE-T) play important role in sustainable management of MSW throughout the world. These technologies reduce the amount of waste as well as produce energy, which can be used to generate electricity. These include thermochemical treatment technologies, biochemical treatment technologies and utilization of landfill gas. Thermochemical techniques include Incineration, Gasification, Pyrolysis, Plasma arc gasification and Hydrothermal carbonization. Incineration is the most common technique used for treatment of MSW. It reduces 70% mass and 90% volume of MSW and sterile ash remains as byproduct. Gasification is advantageous over incineration, as gases are not released into atmosphere. Pyrolysis is the anaerobic thermal degradation of MSW, carried out in an oxygen free environment, producing gases (syngas), liquid and solid residuals. Syngas is composed of methane, hydrogen, carbon mono oxide and carbon dioxide. It can be used in engines, boilers, turbines, fuel cells and heat pumps. Plasma arc gasification also involves partial oxidation of MSW. Syngas and high quality producer gas is obtained that can be used as transport fuel, heat and to generate electricity. Hydrothermal Carbonization (HTC) is a complex process through which hydro-char is produced, which is similar to coal and can be used as a solid fuel for heat and power generation. Organic fraction of MSW is biodegradable and has high energy content. Biochemical treatment technologies are designed to utilize this fraction of MSW. Anaerobic digestion of organic waste is performed by microbes in absence of oxygen in a closed container (biogas digester), resulting in the reduction of waste and production of a combustible gas, biogas, a mixture of methane and carbon dioxide. Landfill gas is rich in methane and must be used to produce heat and energy. It usually consists of 50% methane and 50% CO2. Gas is collected by pipes and reaches the wells installed inside the landfills.

Modeling of gas viscosity at high pressure-high temperature conditions: Integrating radial basis function neural network with evolutionary algorithms

Increase in global natural gas production over the last 15 years has led to the use of new and untapped reservoirs including high pressure-high temperature ones in order to meet the consumer demands. As flow characteristics of gas in various environments such as porous media, wells, and pipelines are influenced by its viscosity, it is an important parameter for petroleum engineers. In this work, an immense gas viscosity dataset consisting of 3017 laboratory data points was used for properly implementing two smart techniques: radial basis function neural network with two training algorithms as well as multilayer perceptron neural network with four training algorithms. By using these techniques, various models with high accuracies were developed for viscosities estimation of gas mixture, pure methane, and pure nitrogen at high pressures (5000–25000 psia) and high temperatures (100–1880 °F). The radial basis function (RBF) neural network with ant colony optimization (ACO) (namely RBF-ACO model) is considered as the best model. Average absolute relative errors of the aforementioned model for estimating pure methane, pure nitrogen and gas mixture viscosities are 0.36 %, 0.49 %, and 1.76 %, respectively. RBF-ACO model provides better results comparing with other presented empirical models. Also, RBF neural network optimized by particle swarm optimization (PSO) shows a high error for estimating the viscosities of methane and gas mixture and RBF neural network optimized by genetic algorithm (GA) yields a high error for estimating the viscosity of gas mixture. Afterwards, effects of input parameters on the viscosity value obtained by RBF-ACO model, were investigated using the relevancy factor. Finally, based on numerical simulation, a sensitivity analysis was conducted for measuring the uncertainty of cumulative gas production resulted from gas viscosity estimation for a high pressure-high temperature gas reservoir. This process indicates that accurate estimation of gas viscosity plays an important role in reliable estimation of cumulative gas production.

Flexible Fuel Operation of a Dry-Low-NOx Micromix Combustor with Variable Hydrogen Methane Mixtures

The role of hydrogen (H2) as a carbon-free energy carrier is discussed since decades for reducing greenhouse gas emissions. As bridge technology towards a hydrogen-based energy supply, fuel mixtures of natural gas or methane (CH4) and hydrogen are possible. The paper presents the first test results of a low-emission Micromix combustor designed for flexible-fuel operation with variable H2/CH4 mixtures. The numerical and experimental approach for considering variable fuel mixtures instead of recently investigated pure hydrogen is described. In the experimental studies, a first generation FuelFlex Micromix combustor geometry is tested at atmospheric pressure at gas turbine operating conditions corresponding to part- and full-load. The H2/CH4 fuel mixture composition is varied between 57 and 100 vol.% hydrogen content. Despite the challenges flexible-fuel operation poses onto the design of a combustion system, the evaluated FuelFlex Micromix prototype shows a significant low NOx performance and high combustion efficiency over a wide fuel range.