Equilibrium in the Methane-Carbon Dioxide-Hydrogen Sulfide-Sulfur System

Sulfur deposition is one of the major bottlenecks in the development of high-sulfur gas reservoirs, while carbon dioxide is one of the main industrial waste gases. Hydrogen sulfide, carbon dioxide, and methane are the primary solvents for elemental sulfur in sour natural gas. If carbon dioxide from industrial emissions could be utilized to enhance the solubility of elemental sulfur in natural gas, it would help suppress sulfur deposition and reduce greenhouse gas emission. Using molecular dynamics simulations, this study explored the feasibility of this concept from the perspective of the microscopic mechanisms of intermolecular interactions. The results show that CO2 injection reduces the solubility of elemental sulfur in hydrogen sulfide but can increase its overall solubility in mixed gases by diluting and replacing methane. These two opposing effects cause the solubility of elemental sulfur in natural gas to vary with the amount of CO2 injected. Overall, the solubility enhancement brought by CO2 injection is limited in magnitude. This study reveals the molecular mechanism underlying the strategy against sulfur deposition by CO2 injection, providing insights for further exploration of its feasibility, effectiveness, process complexity, and cost rationality.

Biogeic sulphur gases emitted from terrestrial ecosystem may play an important role in the global sulphur cycle and have a profound influence on global climate change. In this paper, the emissions of volatile sulphur gases and carbon dioxide from incubated paddy soil were measured. The paddy soils were collected from Nanjing and Yangzhou, China. Six species of sulphur‐containing gases were detected by gas chromatography analysis: hydrogen sulphide (H2S), carbonyl sulphide (COS), methyl mercaptan (CH3SH), carbon disulphide (CS2), dimethyl sulphide (CH3SCH3 or DMS) and dimethyl disulphide (CH3SSCH3 or DMDS). The detected sulphur gases under anaerobic condition (nitrogen) are higher than under aerobic condition (air). After being emitted from soil, these sulphur gases are oxidized and diminished. The values of detected sulphur gases are equal to the difference between the emission and oxidation of sulphur gases. Under aerobic condition, the oxidation rates of sulphur gases were higher than that under anaerobic condition. With the kinetics analysis, it is shown that the emission rates were almost the same under both conditions. There is a positive correlation between the actual emission of total biogenic sulphur gases and carbon dioxide.

During development of high sulfur-content natural gas fields, gaseous sulfur is likely to precipitate and deposit in the reservoir and transmission pipelines owing to changes in the temperature, pressure, and gas components. It is important to accurately predict the elemental sulfur solubility in hydrogen sulfide, carbon dioxide, and methane because these are the three main components of high-sulfur-content natural gas. The binary interaction coefficients between sulfur and hydrogen sulfide, carbon dioxide, and methane are the key parameters for predicting the sulfur solubility with a thermodynamic model. In this work, we show that the binary interaction coefficients are not constant, but temperature dependent. Three-parameter temperature-dependent equations for the binary interaction coefficients between sulfur and solvents are proposed. The corresponding regression equations for calculating the binary interaction coefficients between sulfur and hydrogen sulfide, carbon dioxide, and methane are obtained using experimental sulfur solubility data. The average relative errors of the sulfur solubility predicted using the experimental data in hydrogen sulfide, carbon dioxide, and methane using the thermodynamic model with the improved binary interaction coefficients are 6.30%, 1.69%, and 4.34%, and the average absolute relative errors are 7.90%, 13.12%, and 14.98%, respectively. Comparing the improved binary interaction coefficients with four other sets of reported values shows that the solubility values predicted by the thermodynamic model with improved binary interaction coefficients fit the experimental data better.

Effects of temperature and limestone on sulfur release behaviors during fluidized bed gasification

A rapid method developed for the determination of total sulphur in light petroleum distillate is applied to the determination of total sulphur in natural gas. The sulphur compounds present in the gas are adsorbed on to a small amount of active carbon, which is then allowed to react with a suspension of Raney nickel in a water-propan-2-ol mixture and the sulphur determined as sulphide as described in Part I of this paper. An alternative procedure for the determination of total sulphur in gases containing compounds that are not reduced by Raney nickel is also described. The compounds of sulphur are adsorbed on to active carbon, desorbed into a stream of hydrogen, which then passes through a furnace at 900 °C, and the resulting hydrogen sulphide is determined as a stain on paper impregnated with lead acetate. Methods involving the use of a carbon adsorption tube give results with a precision of ±0·5 mg m–3 of sulphur on samples of stenched natural gas.

Some gas fields with high hydrogen sulfide content, such as Luojiazhai, Dukouhe and Puguang Gas Fields, are found in Northeast Sichuan. For exploring and utilizing high sulfur natural gas reservoirs, it is essential to quantificational analysis of sulfur compounds and elemental sulfur in high sulfur natural gas. Determination of hydrogen sulfide content in natural gas with a laser method has many advantages, including on-site measurement, fast response, wide application scope, high accuracy, high reliability, and low maintenance. When the hydrogen sulfide concentration is 1% to 20%, the relative deviation of the analysis value to the standard value is less than 3% with repeatability of less than 1%. Determination of sulfur compounds in natural gas by gas chromatograph with sulfur chemiluminescence detector (SCD) also has many advantages, such as it is simple, fast, accurate and free from interference of most sample matrixes. The analysis method has good repeatability with lower limit of detection. Since SCD has liner equimolar response to sulfur atom, only one reference gas mixture of sulfur compound is used as external standard calibration. Determination of total sulfur content in natural gas with oxidative microcoulometry method has good repeatability and high accuracy. Determination of elemental sulfur by liquid chromatography has repeatability better than 3%, the detection limit is 10mg/m3, and recovery rate of over 90%, and is applicable for determination of elemental sulfur content in high sulfur natural gas.

Summary. It is well known that sulfur is soluble in sour gas and often precipitates during production if the temperature and pressure decrease. precipitates during production if the temperature and pressure decrease. Of more significance is the possibility of sulfur precipitation in the reservoir as the pressure is reduced. This applies particularly to high- temperature reservoirs, where sulfur is believed to be more viscous, or to moderate-temperature, low-permeability reservoirs. In either case, sulfur precipitation cam impair well productivity and thus the economics precipitation cam impair well productivity and thus the economics of reserve depletion. In the U.S., large sour-gas reserves with reservoir temperatures between 390 and 500 K [242 and 440 degrees F] are being exploited. The purpose of the work was to obtain sufficient sulfur-solubility data in sour gas to develop a widely applicable predictive model of sulfur solubility vs. sour-gas conditions. The data include the effects of temperature, pressure, and gas composition, including variations in the amount and composition of gas-condensate components. Pressures and temperatures ranged from 6.7 to 155 MPa [970 to 22,500 psi] and 394 to 486 K [250 to 415 degrees F], respectively. The influence of H2S on the melting curve was also reported. The value of the experiments was two-fold: to provide information that would allow production and reservoir engineers to predict more reliably the reservoir pressure at which sulfur will precipitate and to yield design data for production systems in which sulfur plugging problems in tubing, flowlines, and production facilities could be avoided. Introduction Many natural gas reservoirs with high concentrations of H2S have recently been discovered. In several of these gas fields, production is severely hampered by elemental sulfur, which is production is severely hampered by elemental sulfur, which is dissolved in the sour gas. The source of this sulfur is not always known. Elemental sulfur sometimes is present in the reservoir as a separate phase. In these cases, the gas is saturated with elemental sulfur. Often, however, elemental sulfur is not present in the reservoir as a detectable separate phase. In these instances, although it is theoretically possible phase. In these instances, although it is theoretically possible for the sour gas to be saturated with elemental sulfur, the gas is usually partially saturated with elemental sulfur. The sulfur solubility is strongly dependent on the pressure, temperature, and composition of the gas. As a result of the geothermal gradient, the gas stream cools as it rises in the tubing, and pressure drops as a result of both the hydrostatic pressure gradient and friction. Consequently, the solubility decreases, and sulfur is deposited whether solubility limit is exceeded. Sulfur may also precipitate in the geological formation and thus impede production because the reservoir pressure usually drops as the reserves are depleted. The presence of sour gas lowers the sulfur freezing point. The freezing presence of sour gas lowers the sulfur freezing point. The freezing point of sulfur may vary from 363 to 393 K [194 to 248 degrees F]. point of sulfur may vary from 363 to 393 K [194 to 248 degrees F]. The actual value depends on crystalline structure, the sour-gas pressure, and the sour-gas composition. Having more data on the pressure, and the sour-gas composition. Having more data on the solubility of sulfur in compressed sour gases of various compositions over a wide range of temperatures and pressures would be of great value in solving the problems associated with production of sulfur- containing sour gas. Some literature is available on the solubility of sulfur in different natural gases and in supercritical H2S. Kennedy and Wieland reported results on (methane+H2S+CO2+sulfur) at pressures of up to 41 MPa [6,000 psi] and at temperatures of 338.7, 366.5, and 394.3 K [150, 200, and 250 degrees F]. Roof measured the solubility of sulfur in H2S up to 31.2 MPa [4,520 psi] and within the 316.5-to-383.2-K [110-to-230 degrees F] temperature range. His results differ considerably from those of Kennedy and Wieland. Swift et al published data on the solubility of sulfur in H2S up to 137.9 MPa and 449.8 K [20,000 psi and 350 degrees F]. Brunner and Woll measured the solubility in sulfur in H2S and in compressed sour gases at pressures of 10.3 to 60.0 MPa [1,500 to 8,700 psi] and at temperatures of 387.6 to 447.6 K [238 to 346 degrees F]. Woll reported data on the influence of sour gases on the melting curve of sulfur. The data presented here are an extension of and are consistent with previous Brunner and Woll data. By means of high-pressure optical cells, we have measured the solubility of sulfur in seven synthetic sour-gas mixtures containing methane, H2S, CO2, nitrogen, and C2 to C6 alkanes. Experimental Techniques The measurements were performed in three high-pressure optical cells of simple design and large capacity: 30, 110, and 550 cm3. The entire contents of the 30- and 110-cm cells could be observed. In conjunction with a simple metering, stirring, and heating system, the cells permitted precise measurement of the solubility of sulfur in compressed sour gases. Fig. 1 shows how the apparatus functions. A known mass of sulfur is first introduced, and the sour gas is then metered stepwise into the thermostatted cell. The mixture is kept thoroughly stirred until the last droplet of sulfur dissolves in the compressed supercritical sour gas. Two different methods were used for metering the mixtures into the high-pressure optical cell. The choice depended on the phase equilibrium of the synthetically mixed sour gases. The first method applies to high H2S concentrations, an example of which is Mixture 1, which is liquid at room temperature. In this case, the mixture is prepared in a thermostatted 1000-cm3 high- pressure autoclave. It is subsequently metered into the pressure autoclave. It is subsequently metered into the optical cell through a thermostatted hand-operated, high-pressure screw press. The second method derives from the fact that at low H2S concentrations, the sour gases are already in the supercritical state at room temperature or at moderately elevated temperatures. The mixtures were prepared in a heated gas cylinder by weighing out the individual gases at pressures of up to 4.8 MPa [696 psi]. They were metered directly into the high-pressure optical cell by means of a diaphragm gas compressor with a heated head. Fig. 2 shows the 30-cm3 cell with two synthetic sapphire windows and a heating jacket. The maximum operating pressure was 200 MPa [29,000 psi]; the maximum operating temperature was 620 K [656 degrees F]. Fig 3 shows the 550-cm cell. Its maximum operating pressure is 100 MPa at 620 K [14,500 psi at 656 degrees F]. Preference is given to this cell for measurements of low sulfur solubilities and sulfur concentrations. The contents of the three cells were stirred by a simple magnetic laboratory stirrer and a PTFE-jacketed bar magnet. The mass of sour gas in equilibrium at the dewpoint pressure and temperature was calculated from the volume of the cell and from separate PVT measurements and density calculations with the Lee-Kesler modification of the Benedict-Webb-Rubin equation of state (EOS) considering the estimated sulfur partial volume in the cell. JPT p. 1587

ABSTRACTDespite the low percentage of trace level sulfur in natural gas (NG), its use as a jet fuel for reduction from the ultra level is very important. Clean and efficient NG as a fuel has major advantages and importance. If the sulfur content of natural gas will decrease in how much it is substantially upgraded. The main problems and difficulties encountered method of removing minor amounts of sulfur remaining in gases after conversion of the major portion of the sulfur content of the gas to elemental sulfur by the Claus or Stretford methods, or any method. Low-quality NG contains hydrogen sulfide, carbon dioxide, and nitrogen, but is not suitable for treatment using current conventional gas treating methods due to economic and environmental challenges. To remove sulfur from natural gas as the most common on the Claus process is applied. However, the Claus process itself is not sufficient for removal of sulfur in the ultra level. The tail gas from the Claus reaction is then passed through a catalytic hydrogenation reactor together with a supply of hydrogen to reduce the sulfur and sulfur compounds to hydrogen sulfide. As a results, hydrogen sulfide is completely removed from the NG streams by washing with alkanolamine solutions.

Sour gas reservoirs are abundant and has promising development prospects in South China, such as Fei Xian Guan group sour gas reservoirs of Luo JiaZai, Pu Guang, Du Kouhe, Tie Shanpo, Long Menchang and Gao Fengchang. The development of sour gas reservoirs will become increasingly more important for meeting the demand of civil natural gas market. However, considerable attention has been devoted to the dangers of hydrogen sulfide during different phases of the natural gas industry, including drilling, completion, development, work-over operations, processing and transportation due to high toxicity and corrosivity of hydrogen sulfide. The characteristics of complex flow through porous media on account of phase behavior variation and sulfur precipitation can also lead to difficulties in scientific studies and production management. In this presentation, an overview of development of sour gas reservoirs in South China was provided including sour gas sample PVT measuring, elemental sulfur deposition evaluation and technical and operational experience and lessons. This work will help improve future management and development of sour gas reservoir development in China and avoid failure in operations. Introduction Sour gas reservoirs are abundant and has promising development prospects in South China, such as Fei Xian Guan group sour gas reservoirs of Luo JiaZai, Pu Guang, Du Kouhe, Tie Shanpo, Long Menchang and Gao Fengchang. The development of sour gas reservoirs will become increasingly more important for meeting the demand of civil natural gas market. However, considerable attention has been devoted to the dangers of hydrogen sulfide during different phases of the natural gas industry, including drilling, completion, development, work-over operations, processing and transportation due to high toxicity and corrosivity of hydrogen sulfide. The characteristics of complex flow through porous media on account of phase behavior variation and sulfur precipitation can also lead to difficulties in scientific studies and production management. Conventional EOS can not accurately and exactly predict gas compressibility, density, and viscosity, which are important properties in the calculations of gas flow through reservoir rocks, material balance calculations, and design of pipelines and production facilities. Li and Guo [1] studied the accuracy of Peng-Robison EOS to predict phase equilibrium of sour gases. Mohsen-Nia et al[2] introduced a two constant EOS, based on theoretical background of statistical mechanics, designed specially to predict properties of sours natural gases. Huron et al.[3] and Evelein and Moore[4] used SRK-EOS to study the hydrocarbon system containing hydrogen sulfide and carbon dioxide. Sulfur precipitation is also an important phenomenon during sour gas production, as shown in Figure 1. Reduction in pressure and temperature induced sulfur precipitation by a reduction in the solubility of the sulfur in the gas phase beyond its thermodynamic saturation point. Sulfur precipitation can impair well productivity and thus the economics precipitation can impair well productivity and thus the economics of reserve depletion[5,6,7]. Kuo and Colsmann[8] developed the first mathematical model of a solid phase precipitation in porous medium and its influence on fluid flow. Roberts[9] have used a conventional black-oil reservoir simulators to model sulfur depositional processes and described significant flow impairment induced by sulfur deposition for a history match of the Waterton field case. Lately, Guo et al.[10] have presented a new gas-liquid-solid coupling model in fractured carbonate gas reservoir with high H2S-content, accounting for sulfur deposition, phase behavior variation, geochemical rock-water-gas interactions, adsorption. Abou-Kassem[11] studied numerically and experimentally the deposition of elemental sulfur in porous medium using gas and oil flow systems. Shedid and Zekri [12] conducted a detailed experimental study using a wide range of applied flow rates, different initial concentrations of sulfur and different rock permeability. Shedid et al[13] also carried out ten dynamic flow experiments using different crude oils of different sulfur and asphaltene concentrations and under different flow rates to investigate the simultaneous deposition of sulfur and asphaltene in porous media. Guo et al. [14] have presented a gas-liquid-solid mathematical model to predict sulfur deposition based on the characteristics of composition and phase behavior of gas-liquid system.

The major gaseous impurities in the subquality natural gas sources are acidic components, such as hydrogen sulfide and carbon dioxide. Considering that H2S easily dissociates into hydrogen and elemental sulfur, thermodynamic properties and specially phase equilibria of liquid and gaseous systems containing hydrogen, hydrogen sulfide, carbon dioxide, other acidic components, and light hydrocarbons are of much interest to the natural gas and gas condensate production industries. In this paper we report the development of a simple and accurate cubic equation of state for prediction of thermodynamic properties and phase behavior of sour natural gas and liquid mixtures. This cubic equation of state, which is based on statistical mechanical theoretical grounds, is applied to pure fluids as well as mixtures with quite accurate results. All the thermodynamic property relations of sour gaseous and liquid mixtures are derived and reported in this report. Parameters of this equation of state are derived for different components of sour natural gas systems. The resulting equation of state is tested for phase behavior and other thermodynamic properties of simulated and natural sour gas mixtures. It is shown that the present equation of state, even though it is simple, predicts the properties of interest with ease and accuracy.

Currently, the obtaining of environmentally friendly fuels is of scientific and practical interest, since the main pollutants of the environment are motor fuels, the combustion of which releases a large number of hazardous pollutants into the atmosphere along with exhaust gases. The article considers the process of extraction dearomatization of diesel fuel using ionic liquid morpholinformate as an extractant, then subsequent involvement in the composition of the obtained dearomatized diesel fuel as an oxygen-containing additive 5-10% methyl esters of natural petroleum acids. It was found that the yield of dearomatized diesel fuel in the process of extraction dearomatization is 84.8%. As a result, the content of sulfur and aromatic hydrocarbons in the dearomatized diesel fuel composition is reduced to 0,0216% and 0,8%, respectively. Then, 5-10% compounds based on dearomatized diesel fuel and methyl esters of natural petroleum acids were made and their quality indicators were studied. It was found that adding the latter to the dearomatized diesel fuel composition has a favorable effect on the quality indicators of the obtained compounds. Thus, the sulfur content in their composition decreases and amounts to 0,0205-0,0187%, and the aromatic hydrocarbon content is 0,6-0,3%. At the same time, the antiwear properties of the obtained 5-10% compounds were studied and it was found that their wear scar diameter decreases and amounts to 0,457 and 0,423 mm, respectively. In addition, the composition of exhaust gases during combustion of the original diesel fuel, dearomatized diesel fuel and dearomatized diesel fuel containing 10% methyl esters of natural petroleum acids was studied and a decrease in the content of carbon oxides, sulfur and nitrogen in the exhaust gases was found.

Effective use of hydrogen sulfide and natural gas resources available in the Black Sea for hydrogen economy

The influences of soil sulfate content on the transformations of nitrate and sulfate during the reductive soil disinfestation (RSD) process

Genesis and distribution of hydrogen sulfide in deep heavy oil of the Halahatang area in the Tarim Basin, China

Coal combustion in CO2/O2 (oxy-fuel combustion) allows reducing fossil carbon dioxide emissions in the atmosphere. The change of oxidizer from N2/O2 (air) to CO2/O2 changes the combustion process, including pyrolysis. The formation of sulfur and chlorine species during temperature-programmed coal pyrolysis in N2 and CO2 atmosphere and with heating rates of 10 and 20 K/min was studied. Two high volatile bituminous coals with different sulfur content but almost identical relative distribution of sulfur species (sulfide, pyritic, sulfate, and organic) were used in the experiments. The release of H2S, SO2, COS, and HCl was determined using mass spectrometry. Two and three peaks were observed in the hydrogen sulfide and sulfur dioxide release profiles, respectively, which are caused by the different sulfur species present in the coals. It was found that the release profile of sulfur dioxide varies for the coals, which means that information about sulfur forms is not sufficient to predict SO2 formation during p...