Journal articles: 'Natural gas/hydrogen mixtures'

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Gaathaug, André Vagner, Dag Bjerketvedt, Knut Vaagsaether, and Sandra Hennie Nilsen. "Experimental Study of Gas Explosions in Hydrogen Sulfide-Natural Gas-Air Mixtures." Journal of Combustion 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/905893.

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An experimental study of turbulent combustion of hydrogen sulfide (H2S) and natural gas was performed to provide reference data for verification of CFD codes and direct comparison. Hydrogen sulfide is present in most crude oil sources, and the explosion behaviour of pure H2S and mixtures with natural gas is important to address. The explosion behaviour was studied in a four-meter-long square pipe. The first two meters of the pipe had obstacles while the rest was smooth. Pressure transducers were used to measure the combustion in the pipe. The pure H2S gave slightly lower explosion pressure than pure natural gas for lean-to-stoichiometric mixtures. The rich H2S gave higher pressure than natural gas. Mixtures of H2S and natural gas were also studied and pressure spikes were observed when 5% and 10% H2S were added to natural gas and also when 5% and 10% natural gas were added to H2S. The addition of 5% H2S to natural gas resulted in higher pressure than pure H2S and pure natural gas. The 5% mixture gave much faster combustion than pure natural gas under fuel rich conditions.

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Karp, I. M. "HYDROGEN IN MUNICIPAL ENERGY." Energy Technologies & Resource Saving, no. 1 (March 20, 2021): 23–26. http://dx.doi.org/10.33070/etars.1.2021.02.

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The use of hydrogen in the municipal energy sector is currently inappropriate due to its high cost. Production of hydrogen by electrolysis requires more energy than it is emitted during its combustion. Thermophysical properties of hydrogen and natural gas are compared. Heat value of hydrogen in a unit of volume is 3.3 times lower than that of methane. The cost per unit of energy in hydrogen is more than 10 times higher than in natural gas. Distribution gas networks are not suitable for transportation of pure hydrogen. The possibility of transporting hydrogen in mixtures with natural gas is being studied. The efficiency of fuel use in a heating gas boiler decreases with increasing hydrogen concentration in a mixture with natural gas up to 50 %. The concentration of nitrogen oxides does not depend on the hydrogen content in the mixture. Bibl. 4, Table 1.

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Dehdari, Leila, Iris Burgers, Penny Xiao, Kevin Gang Li, Ranjeet Singh, and Paul A. Webley. "Purification of hydrogen from natural gas/hydrogen pipeline mixtures." Separation and Purification Technology 282 (February 2022): 120094. http://dx.doi.org/10.1016/j.seppur.2021.120094.

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Jaworski, Jacek, Paweł Kułaga, Giorgio Ficco, and Marco Dell’Isola. "Domestic Gas Meter Durability in Hydrogen and Natural Gas Mixtures." Energies 14, no. 22 (November 12, 2021): 7555. http://dx.doi.org/10.3390/en14227555.

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Blending hydrogen into the natural gas infrastructure is becoming a very promising practice to increase the exploitation of renewable energy sources which can be used to produce “green” hydrogen. Several research projects and field experiments are currently aimed at evaluating the risks associated with utilization of the gas blend in end-use devices such as the gas meters. In this paper, the authors present the results of experiments aimed at assessing the effect of hydrogen injection in terms of the durability of domestic gas meters. To this end, 105 gas meters of different measurement capabilities and manufacturers, both brand-new and withdrawn from service, were investigated in terms of accuracy drift after durability cycles of 5000 and 10,000 h with H2NG mixtures and H2 concentrations of 10% and 15%. The obtained results show that there is no metrologically significant or statistically significant influence of hydrogen content on changes in gas meter indication errors after subjecting the meters to durability testing with a maximum of 15% H2 content over 10,000 h. A metrologically significant influence of the long-term operation of the gas meters was confirmed, but it should not be made dependent on the hydrogen content in the gas. No safety problems related to the loss of external tightness were observed for either the new or 10-year-old gas meters.

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Shkarovskiy, Alexander, Anatolii Koliienko, and Vitalii Turchenko. "INTERCHANGEABILITY AND STANDARDIZATION OF THE PARAMETERS OF COMBUSTIBLE GASES WHEN USING HYDROGEN." Architecture and Engineering 7, no. 1 (March 31, 2022): 33–45. http://dx.doi.org/10.23968/2500-0055-2022-7-1-33-45.

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Introduction and purpose of the study: The paper presents results of studies aimed to provide a rationale for the possibility of a gradual transition to hydrogen combustion in gas supply to domestic and commercial consumers without changes in the design and operation of burners. For this purpose, we have considered tasks of determining the indicators of interchangeability for natural gas and its mixtures with hydrogen. The main characteristics of combustible gases with various hydrogen content in a mixture have been studied. We have established the impact of the hydrogen content on the heat rate, emissions of harmful substances, as well as light back and flame lift phenomena. We have also analyzed the available interchangeability criteria and their applicability when using natural gas/hydrogen mixtures. The impact of the hydrogen content on the radiation heat transfer in the furnaces of gas equipment is described in the paper for the first time. Methods: The methodology of the paper is based on a critical analysis of available literature data on combustible gases interchangeability as well as theoretical and experimental studies performed by the authors. We have derived dependencies that allow us to determine the possibility of gas equipment transition to the combustion of natural gas/hydrogen mixtures. We have also developed recommendations on the permissible hydrogen content in a natural gas/ hydrogen mixture that would ensure the efficient, safe, and green use of such fuel in domestic and commercial heating units. Results: Scientific findings and practical results of the study make it possible to implement partial gradual costeffective decarbonization in the area of gas fuel utilization as an intermediate stage of transition to more extended hydrogen combustion.

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Makaryan, Iren A., Igor V. Sedov, Eugene A. Salgansky, Artem V. Arutyunov, and Vladimir S. Arutyunov. "A Comprehensive Review on the Prospects of Using Hydrogen–Methane Blends: Challenges and Opportunities." Energies 15, no. 6 (March 20, 2022): 2265. http://dx.doi.org/10.3390/en15062265.

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An analysis of the literature data indicates a wide front of research and development in the field of the use of methane–hydrogen mixtures as a promising environmentally friendly low-carbon fuel. The conclusion of most works shows that the use of methane–hydrogen mixtures in internal combustion engines improves their performance and emission characteristics. The most important aspect is the concentration of hydrogen in the fuel mixture, which affects the combustion process of the fuel and determines the optimal operating conditions of the engine. When using methane–hydrogen mixtures with low hydrogen content, the safety measures and risks are similar to those that exist when working with natural gas. Serious logistical problems are associated with the difficulties of using the existing gas distribution infrastructure for transporting methane–hydrogen mixtures. It is possible that, despite the need for huge investments, it will be necessary to create a new infrastructure for the production, storage and transportation of hydrogen and its mixtures with natural gas. Further research is needed on the compatibility of pipeline materials with hydrogen and methane–hydrogen mixtures, safety conditions for the operation of equipment operating with hydrogen or methane–hydrogen mixtures, as well as the economic and environmental feasibility of using these energy carriers.

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Zéberg-Mikkelsen, Claus K., Sergio E. Quiñones-Cisneros, and Erling H. Stenby. "Viscosity Prediction of Hydrogen + Natural Gas Mixtures (Hythane)." Industrial & Engineering Chemistry Research 40, no. 13 (June 2001): 2966–70. http://dx.doi.org/10.1021/ie0010464.

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Melnyk, V. М., F. V. Kozak, М. М. Hnyp, and D. V. Lisafin. "Efficiency of hydrogen use in mixtures with compressed natural gas on car engines." Oil and Gas Power Engineering, no. 2(36) (December 29, 2021): 106–19. http://dx.doi.org/10.31471/1993-9868-2021-2(36)-98-105.

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One of the important aspects of using hydrogen in an equivalent fuel is economic efficiency. In the calculations of the economic efficiency of the use of hydrogen as an additive to compressed natural gas, the necessary technical condition is to ensure the same calorific value of the equivalent fuel in comparison with commercial natural gas. To solve this problem, we obtained the dependence of the change in the price of natural gas on the lower heat of combustion, calculated the change in the consumption of equivalent fuel from the equation of heat balance contained in compressed natural gas and equivalent fuel. Depending on the increase in the lower heat of combustion when adding hydrogen, we obtained the value of the heat of combustion of compressed gas that can be used in mixtures with hydrogen. Therefore, for the accepted prices for compressed natural gas and hydrogen and under the same calorific value of equivalent fuel and compressed natural gas from the calculations it is seen that with increasing percentage of hydrogen in fuel mixtures of natural gas and hydrogen increases economic efficiency. This is due to the use in fuel mixtures of natural gas with low calorific value, and hence low cost, and as an option it can be biogas. When using hydrogen additives to compressed natural gas with low calorific value in the amount of up to 70% by weight, you can achieve a reduction in the cost of natural gas to 12.5 UAH on kilogram. This effect, when using hydrogen additives to natural gas, indicates the prospects of this direction of hydrogen use and the feasibility of further research.

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Huszal, Anna, and Jacek Jaworski. "Studies of the Impact of Hydrogen on the Stability of Gaseous Mixtures of THT." Energies 13, no. 23 (December 5, 2020): 6441. http://dx.doi.org/10.3390/en13236441.

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One of the most important requirements concerning the quality of natural gases, guaranteeing their safe use, involves providing the proper level of their odorization. This allows for the detection of uncontrolled leakages of gases from gas networks, installations and devices. The concentration of an odorant should be adjusted in such a manner that the gas odor in a mixture with air would be noticeable by users (gas receivers). A permanent odor of gas is guaranteed by the stability of the odorant molecule and its resistance to changes in the composition of odorized gases. The article presents the results of experimental research on the impact of a hydrogen additive on the stability of tetrahydrothiophene (THT) mixtures in methane and in natural gas with a hydrogen additive. The objective of the work was to determine the readiness of measurement infrastructures routinely used in monitoring the process of odorizing natural gas for potential changes in its composition. One of the elements of this infrastructure includes the reference mixtures of THT, used to verify the correctness of the readings of measurement devices. The performed experimental tests address possible changes in the composition of gases supplied via a distribution network, resulting from the introduction of hydrogen. The lack of interaction between hydrogen and THT has been verified indirectly by assessing the stability of its mixtures with methane and natural gas containing hydrogen. The results of the presented tests permitted the identification of potential hazards for the safe use of gas from a distribution network, resulting from changes in its composition caused by the addition of hydrogen.

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Sierens, R., and E. Rosseel. "Variable Composition Hydrogen/Natural Gas Mixtures for Increased Engine Efficiency and Decreased Emissions." Journal of Engineering for Gas Turbines and Power 122, no. 1 (July 5, 1999): 135–40. http://dx.doi.org/10.1115/1.483191.

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It is well known that adding hydrogen to natural gas extends the lean limit of combustion and that in this way extremely low emission levels can be obtained: even the equivalent zero emission vehicle (EZEV) requirements can be reached. The emissions reduction is especially important at light engine loads. In this paper results are presented for a GM V8 engine. Natural gas, pure hydrogen and different blends of these two fuels have been tested. The fuel supply system used provides natural gas/hydrogen mixtures in variable proportion, regulated independently of the engine operating condition. The influence of the fuel composition on the engine operating characteristics and exhaust emissions has been examined, mainly but not exclusively for 10 and 20 percent hydrogen addition. At least 10 percent hydrogen addition is necessary for a significant improvement in efficiency. Due to the conflicting requirements for low hydrocarbons and low NOx, determining the optimum hythane composition is not straight-forward. For hythane mixtures with a high hydrogen fraction, it is found that a hydrogen content of 80 percent or less guarantees safe engine operation (no backfire nor knock), whatever the air excess factor. It is shown that to obtain maximum engine efficiency for the whole load range while taking low exhaust emissions into account, the mixture composition should be varied with respect to engine load. [S0742-4795(00)02001-9]

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AKANSU, S. "Internal combustion engines fueled by natural gas?hydrogen mixtures." International Journal of Hydrogen Energy 29, no. 14 (November 2004): 1527–39. http://dx.doi.org/10.1016/j.ijhydene.2004.01.018.

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Lowesmith, Barbara Joan, and Geoffrey Hankinson. "Large scale high pressure jet fires involving natural gas and natural gas/hydrogen mixtures." Process Safety and Environmental Protection 90, no. 2 (March 2012): 108–20. http://dx.doi.org/10.1016/j.psep.2011.08.009.

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Shang, Juan, Weifeng Chen, Jinyang Zheng, Zhengli Hua, Lin Zhang, Chengshuang Zhou, and Chaohua Gu. "Enhanced hydrogen embrittlement of low-carbon steel to natural gas/hydrogen mixtures." Scripta Materialia 189 (December 2020): 67–71. http://dx.doi.org/10.1016/j.scriptamat.2020.08.011.

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14

Potemkin, D. I., S. I. Uskov, A. M. Gorlova, V. A. Kirillov, A. B. Shigarov, A. S. Brayko, V. N. Rogozhnikov, et al. "Low-temperature Steam Reforming of Natural Gas to Methane-Hydrogen Mixtures." Kataliz v promyshlennosti 20, no. 3 (May 28, 2020): 184–89. http://dx.doi.org/10.18412/1816-0387-2020-3-184-189.

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Thermodynamic analysis of the steam reforming of natural gas at a temperature of 300–600 °C, pressure 0.1–4 MPa and Н2О : С molar ratio 0.8–1.2 was carried out. Under these conditions, the reaction products are methane-hydrogen mixtures with the hydrogen concentration 10–30 vol.%. Raising the temperature and Н2О : С molar ratio as well as decreasing the pressure make it possible to increase the hydrogen concentration in the reaction products. Thermodynamic boundaries of the process in the absence of catalyst coking were determined. Experiments on the formation of methane-hydrogen mixtures from methane with the outlet hydrogen concentration 15–35 vol.% were performed on a commercial Ni-CrOx-Al2O3 catalyst at a temperature of 325–425 °С, Н2О : С molar ratio 0.8–1.0, and atmospheric pressure. Under the indicated conditions, the process was not accompanied by the formation of carbon on the catalyst.

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Amez, Isabel, Blanca Castells, Bernardo Llamas, David Bolonio, María Jesús García-Martínez, José L. Lorenzo, Javier García-Torrent, and Marcelo F. Ortega. "Experimental Study of Biogas–Hydrogen Mixtures Combustion in Conventional Natural Gas Systems." Applied Sciences 11, no. 14 (July 15, 2021): 6513. http://dx.doi.org/10.3390/app11146513.

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Biogas is a renewable gas with low heat energy, which makes it extremely difficult to use as fuel in conventional natural gas equipment. Nonetheless, the use of hydrogen as a biogas additive has proven to have a beneficial effect on flame stability and combustion behavior. This study evaluates the biogas–hydrogen combustion in a conventional natural gas burner able to work up to 100 kW. Tests were performed for three different compositions of biogas: BG70 (30% CO2), BG60 (40% CO2), and BG50 (50% CO2). To achieve better flame stability, each biogas was enriched with hydrogen from 5% to 25%. The difficulty of burning biogas in conventional systems was proven, as the burner does not ignite when the biogas composition contains more than 40% of CO2. The best improvements were obtained at 5% hydrogen composition since the exhaust gas temperature and, thus, the enthalpy, rises by 80% for BG70 and 65% for BG60. The stability map reveals that pure biogas combustion is unstable in BG70 and BG60; when the CO2 content is 50%, ignition is inhibited. The properties change slightly when the hydrogen concentrations are more than 20% in the fuel gas and do not necessarily improve.

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Zhang, Ning, Jie Liu, Junle Wang, and Hongbo Zhao. "On the laminar combustion characteristics of natural gas-syngas-air mixtures." Thermal Science 22, no. 5 (2018): 2077–86. http://dx.doi.org/10.2298/tsci171229255z.

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In this study, the effects of hydrogen and CO addition on the laminar flame speed and flame instabilities of CH4/air mixture are investigated experimentally and numerically. Results show that laminar flame speeds increase almost linearly with the addition of hydrogen, which is mainly caused by the increase of the flame temperature and the thermal diffusivity of the mixture. However, it de-creases with the increase of the pressure, which is mainly due to the increase of the mixture density and the enhancement of the termination reactions. The hydrodynamic instability is increased with the increase of hydrogen ratio and pressure, which is due to the reduction of the flame thickness. With the increase of hydrogen fractions and pressure, the Markstein lengths decrease obviously, which means the flame instability is enhanced. The addition of CO has little effect on the flame speeds and flame instabilities.

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Serbin, Serhiy, Kateryna Burunsuz, and Daifen Chen. "Investigation of the Characteristics of a Gas Turbine Combustion Chamber with Steam Injection Operating on Hydrogen-Containing Mixtures and Hydrogen." International Journal of Chemical Engineering 2022 (December 17, 2022): 1–12. http://dx.doi.org/10.1155/2022/9123639.

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The article is devoted to the investigation of the characteristics of a gas turbine combustion chamber with a steam injection when operating on hydrogen-containing mixtures and pure hydrogen. The parameters of a cannular combustion chamber with a separate injection of ecological and energy steam were studied to ensure the stable and ecologically clean chamber’s operation without the formation of flashback zones. The injection of ecological steam in the area of the vane swirler of the flame tube for the diffusion-type combustion chamber makes it possible to provide low emissions of nitrogen oxides at significant concentrations of hydrogen in its mixtures with natural gas, even if the maximum gas temperature in the primary zone of a combustion chamber increases. For the investigated chamber’s operating modes, the calculated carbon monoxide emission does not exceed 18.1 ppm. Emissions of nitrogen oxide when the hydrogen content changes from 0 to 50% initially decrease from 36.1 to 17.8 ppm due to increased steam injection to the combustion zone and then increase to 38 ppm when operating on pure hydrogen. An increase in the nonuniformity of the temperature field at the combustion chamber outlet with an increase in the hydrogen content in the mixture with natural gas was noted.

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Kuczyński, Szymon, Mariusz Łaciak, Andrzej Olijnyk, Adam Szurlej, and Tomasz Włodek. "Thermodynamic and Technical Issues of Hydrogen and Methane-Hydrogen Mixtures Pipeline Transmission." Energies 12, no. 3 (February 12, 2019): 569. http://dx.doi.org/10.3390/en12030569.

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The use of hydrogen as a non-emission energy carrier is important for the innovative development of the power-generation industry. Transmission pipelines are the most efficient and economic method of transporting large quantities of hydrogen in a number of variants. A comprehensive hydraulic analysis of hydrogen transmission at a mass flow rate of 0.3 to 3.0 kg/s (volume flow rates from 12,000 Nm3/h to 120,000 Nm3/h) was performed. The methodology was based on flow simulation in a pipeline for assumed boundary conditions as well as modeling of fluid thermodynamic parameters for pure hydrogen and its mixtures with methane. The assumed outlet pressure was 24 bar (g). The pipeline diameter and required inlet pressure were calculated for these parameters. The change in temperature was analyzed as a function of the pipeline length for a given real heat transfer model; the assumed temperatures were 5 and 25 °C. The impact of hydrogen on natural gas transmission is another important issue. The performed analysis revealed that the maximum participation of hydrogen in natural gas should not exceed 15%–20%, or it has a negative impact on natural gas quality. In the case of a mixture of 85% methane and 15% hydrogen, the required outlet pressure is 10% lower than for pure methane. The obtained results present various possibilities of pipeline transmission of hydrogen at large distances. Moreover, the changes in basic thermodynamic parameters have been presented as a function of pipeline length for the adopted assumptions.

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Subani, Norazlina, and Norsarahaida Amin. "The effect of mass ratio on the flow characteristics of hydrogen-natural gas mixture using reduced order modelling." Malaysian Journal of Fundamental and Applied Sciences 13, no. 4-1 (December 5, 2017): 381–89. http://dx.doi.org/10.11113/mjfas.v13n4-1.801.

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This work focuses on the development of a mathematical model as a viable alternative to pinpoint locations of gas leaks in a pipeline. The transient non-isothermal flow of hydrogen-natural gas mixture is considered because hydrogen is often transported in the same pipeline as natural gas to reduce the transportation cost. The mathematical model developed took into consideration the effect of the mass ratio of gas mixture. The gas mixture was assumed to be homogeneous and the transient pressure wave was created by the sudden or instantaneous closure of a downstream shut-off valve to ensure the attainment of minimum pressure at the downstream end within a short time. The governing equations were numerically solved using the reduced order modelling (ROM) technique, which had not been previously applied on non-isothermal models involving gas mixtures. Numerical results observed that the mass ratio of hydrogen to natural gas should not be more than 0.5 to ensure that leakage does not occur before the estimated leak position. An increase in the mass ratio leads to an increase in the pressure and celerity wave, while the leak location and the amount of leak discharge decrease.

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ONEY, F., T. VEZIROLU, and Z. DULGER. "Evaluation of pipeline transportation of hydrogen and natural gas mixtures." International Journal of Hydrogen Energy 19, no. 10 (October 1994): 813–22. http://dx.doi.org/10.1016/0360-3199(94)90198-8.

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Meng, Bo, Chaohua Gu, Lin Zhang, Chengshuang Zhou, Xiongying Li, Yongzhi Zhao, Jinyang Zheng, Xingyang Chen, and Yong Han. "Hydrogen effects on X80 pipeline steel in high-pressure natural gas/hydrogen mixtures." International Journal of Hydrogen Energy 42, no. 11 (March 2017): 7404–12. http://dx.doi.org/10.1016/j.ijhydene.2016.05.145.

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Dell’Isola, Marco, Giorgio Ficco, Linda Moretti, Alessandra Perna, Daniele Candelaresi, and Giuseppe Spazzafumo. "Impact of hydrogen injection on thermophysical properties and measurement reliability in natural gas networks." E3S Web of Conferences 312 (2021): 01004. http://dx.doi.org/10.1051/e3sconf/202131201004.

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In the context of the European decarbonization strategy, hydrogen is a key energy carrier in the medium to long term. The main advantages deriving from a greater penetration of hydrogen into the energy mix consist in its intrinsic characteristics of flexibility and integrability with alternative technologies for the production and consumption of energy. In particular, hydrogen allows to: i) decarbonise end uses, since it is a zero-emission energy carrier and can be produced with processes characterized by the absence of greenhouse gases emissions (e.g. water electrolysis); ii) help to balancing electricity grid supporting the integration of non-programmable renewable energy sources; iii) exploit the natural gas transmission and distribution networks as storage systems in overproduction periods. However, the hydrogen injection into the natural gas infrastructures directly influences thermophysical properties of the gas mixture itself, such as density, calorific value, Wobbe index, speed of sound, etc [1]. The change of the thermophysical properties of gaseous mixture, in turn, directly affects the end use service in terms of efficiency and safety as well as the metrological performance and reliability of the volume and gas quality measurement systems. In this paper, the authors present the results of a study about the impact of hydrogen injection on the properties of the natural gas mixture. In detail, the changes of the thermodynamic properties of the gaseous mixtures with different hydrogen content have been analysed. Moreover, the theoretical effects of the aforementioned variations on the accuracy of the compressibility factor measurement have been also assessed.

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Aryal, Utsav Raj, Majid Aziz, and Ajay Krishna Prasad. "(Invited) Electrochemical Gas Separation." ECS Meeting Abstracts MA2022-02, no. 27 (October 9, 2022): 1031. http://dx.doi.org/10.1149/ma2022-02271031mtgabs.

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Electrochemical gas separators are electrically powered systems that selectively remove a targeted gas species from a mixture of gases by virtue of electrochemical reactions. Electrochemical separation is an attractive option owing to its higher efficiency and lower cost compared to incumbent technologies like pressure swing adsorption, cryogenic processes, and selective permeation. This work focuses on two specific electrochemical separation processes – (1) separation of hydrogen from a mixture of gases to help develop the hydrogen distribution infrastructure, and (2) nitrogen separation from air for aircraft fuel tank inerting. Reductions in CO2 emission since the beginning of this century by the US electric power sector are mainly attributed to the replacement of coal by natural gas in power plants. Nevertheless, the combustion of natural gas still contributes heavily to global warming and climate change. It is imperative to find alternatives to combustion-based energy technologies and nurture the growth of renewable energy systems. In this scenario, hydrogen is a leading candidate as a carbon-free fuel with high energy density and is expected to play a key role in future energy systems. However, hydrogen faces serious obstacles in its distribution due to the lack of a nationwide hydrogen pipeline network. Developing a dedicated hydrogen pipeline network will be quite expensive, therefore, it is worthwhile to examine whether existing natural gas pipelines could be effectively deployed for hydrogen distribution. This would be accomplished by directly injecting a prescribed amount of hydrogen at the point of production into a natural gas pipeline. Such a mixture of hydrogen and methane is labeled as hythane. While this enables the convenient transport of hydrogen across large distances, the process can only be completed by separating hydrogen from methane at the destination point. Electrochemical hydrogen separation (ECHS) systems built around proton-selective polymer electrolyte membranes (PEMs) represent an effective platform to separate and simultaneously compress hydrogen in a continuous operation. Furthermore, ECHS ensures that the resulting gas is not contaminated by lubrication oil as observed in conventional systems. In ECHS, the hythane mixture enters the anode compartment wherein the hydrogen is selectively dissociated to protons and electrons. The protons are then driven across the PEM by an externally applied voltage to recover hydrogen at the cathode. The first part of this study demonstrates hydrogen purification using low-temperature PEM-based ECHS from various gas mixtures including methane/hydrogen, carbon dioxide/hydrogen, water gas shift effluent, and hythane. ECHS performance is first investigated for pure hydrogen as a function of membrane thickness, cell temperature, and relative humidity of the anode stream. In the second set of experiments, various ratios of methane/hydrogen and carbon dioxide/hydrogen are introduced to examine the effect of hydrogen concentration in the feed gas mixture on ECHS performance. Finally, experiments are performed for hydrogen purification from a water gas shift (WGS) effluent mixture as well as a practical hythane gas feed. ECHS performance for all gas mixtures was benchmarked against the pure hydrogen case. The purity of the separated hydrogen gas was measured to confirm the effectiveness of the method. The results show that ECHS represents a good solution to separate hydrogen from the hythane mixture at the downstream end of the pipeline. Pertinent to the second electrochemical separation process examined here, after the TWA flight 800 disaster due to a fuel tank explosion in 1996, inerting of aircraft fuel tanks became a priority. During fuel tank inerting, an inert gas like nitrogen is supplied to the tank to reduce its flammability. An electrochemical gas separation and inerting system (EGSIS) is a device that generates nitrogen enriched air (NEA) from ambient air by the application of electrical power. EGSIS combines a PEM electrolyzer anode wherein water is dissociated to release oxygen, and a PEM fuel cell cathode where atmospheric air is converted to NEA. Aircraft tank inerting requires varying NEA flowrates (low during takeoff and ascent, and high during descent). In conventional hollow fiber membrane air separation modules typically used in current aircraft, the total membrane surface area is determined by the maximum required NEA flow rate which results in large and expensive modules. On the other hand, the NEA flow rate can be easily controlled in EGSIS by simply adjusting the applied voltage. This portion of the study focuses on results for a single EGSIS cell and its optimization. Various EGSIS stack configurations are also described in order to develop a practical system. Finally, a techno-economic analysis of EGSIS is presented to show that EGSIS can compete favorably with incumbent technologies in terms of fuel usage and cost.

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Dell’Isola, Marco, Giorgio Ficco, Linda Moretti, Jacek Jaworski, Paweł Kułaga, and Ewa Kukulska–Zając. "Impact of Hydrogen Injection on Natural Gas Measurement." Energies 14, no. 24 (December 15, 2021): 8461. http://dx.doi.org/10.3390/en14248461.

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Hydrogen is increasingly receiving a primary role as an energy vector in ensuring the achievement of the European decarbonization goals by 2050. In fact, Hydrogen could be produced also by electrolysis of water using renewable sources, such as photovoltaic and wind power, being able to perform the energy storage function, as well as through injection into natural gas infrastructures. However, hydrogen injection directly impacts thermodynamic properties of the gas itself, such as density, calorific value, Wobbe index, sound speed, etc. Consequently, this practice leads to changes in metrological behavior, especially in terms of volume and gas quality measurements. In this paper, the authors present an overview on the impact of hydrogen injection in natural gas measurements. In particular, the changes in thermodynamic properties of the gas mixtures with different H2 contents have been evaluated and the effects on the accuracy of volume conversion at standard conditions have been investigated both on the theoretical point of view and experimentally. To this end, the authors present and discuss the effect of H2 injection in gas networks on static ultrasonic domestic gas meters, both from a theoretical and an experimental point of view. Experimental tests demonstrated that ultrasonic gas meters are not significantly affected by H2 injection up to about 10%.

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Bölkény, Ildikó, Gábor Hegyi, and Angéla Váradiné Szarka. "Possibilities of measuring hydrogen in natural gas." Multidiszciplináris tudományok 11, no. 5 (2021): 188–94. http://dx.doi.org/10.35925/j.multi.2021.5.19.

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Green hydrogen produced by renewable energies is an innovative use of mixed with natural gas to deliver the mixture to end users using existing natural gas storage and networks, thereby achieving increased performance. In such a new technology, measuring the hydrogen content of a hydrogen natural gas mixture is essential. This paper provides an overview of hydrogen sensors.

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Budak, Paweł, and Tadeusz Szpunar. "Zmiany parametrów mieszaniny gazu ziemnego z wodorem w trakcie eksploatacji komory magazynowej w kawernie solnej." Nafta-Gaz 76, no. 11 (November 2020): 799–806. http://dx.doi.org/10.18668/ng.2020.11.05.

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Underground gas stores are built in depleted gas reservoirs or in salt domes or salt caverns. In the case of salt caverns, the store space for gas is created by leaching the salt using water. Gas stores in salt caverns are capable to provide the distribution network with large volumes of gas in a short time and cover the peak demand for gas. The salt caverns are also capable to store large volumes of gas in case when there is too much gas on a market. Generally, the salt caverns are used to mitigate the fluctuation of gas demand, specifically during winter. The gas provided to the distribution network must satisfy the requirements regarding its heating value, calorific value, volumetric content of hydrogen and the Wobbe number. Large hydrogen content reduces the calorific value as well as the heating value of gas and thus its content must be regulated to keep these values at the acceptable level. One should also remember that every portion of gas which was used to create the gas/hydrogen mixture may have different parameters (heating value and calorific value) because it may come from different sources. The conclusion is that the hydrogen content and the heating value must be known at every moment of gas store exploitation. The paper presents an algorithm and a computer program which may be used to calculate the hydrogen content (volumetric percentage), heating value and calorific value (plus the Wobbe number) of gas collected from the salt cavern at every moment of cavern exploitation. The possibility of the presence of non-flammable components in the mixture and their effect on the heat of combustion / calorific value were considered. An exemplary calculation is provided.

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Neacsa, Adrian, Cristian Nicolae Eparu, and Doru Bogdan Stoica. "Hydrogen–Natural Gas Blending in Distribution Systems—An Energy, Economic, and Environmental Assessment." Energies 15, no. 17 (August 24, 2022): 6143. http://dx.doi.org/10.3390/en15176143.

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Taking into account the international policies in the field of environmental protection in the world in general, and in the European Union in particular, the reduction of greenhouse gas (GHG) emissions, and primarily of carbon dioxide, has become one of the most important objectives. This can be obtained through various renewable energy sources and non-polluting technologies, such as the mixing of hydrogen and natural gas. Combining hydrogen with natural gas is an emerging trend in the energy industry and represents one of the most important changes in the efforts to achieve extensive decarbonisation. The importance of this article consists of carrying out a techno-economic study based on the simulation of annual consumptions regarding the construction and use of production capacities for hydrogen to be used in mixtures with natural gas in various percentages in the distribution network of an important operator in Romania. In order to obtain relevant results, natural gas was treated as a mixture of real gases with a known composition as defined in the chromatographic bulletin. The survey presents a case study for the injection of 5%, 10%, and 20% hydrogen in the natural gas distribution system of Bucharest, the largest city in Romania. In addition to conducting this techno-economic study, the implications for final consumers of this technical solution in reducing greenhouse gas emissions—mainly those of carbon dioxide from combustion—are also presented.

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Potemkin, D. I., S. I. Uskov, A. M. Gorlova, V. A. Kirillov, A. B. Shigarov, A. S. Brayko, V. N. Rogozhnikov, et al. "Low-Temperature Steam Conversion of Natural Gas to Methane–Hydrogen Mixtures." Catalysis in Industry 12, no. 3 (July 2020): 244–49. http://dx.doi.org/10.1134/s2070050420030101.

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Huang, Zuohua, Yong Zhang, Qian Wang, Jinhua Wang, Deming Jiang, and Haiyan Miao. "Study on Flame Propagation Characteristics of Natural Gas−Hydrogen−Air Mixtures." Energy & Fuels 20, no. 6 (November 2006): 2385–90. http://dx.doi.org/10.1021/ef060334v.

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Elaoud, Sami, Zahreddine Hafsi, and Lamjed Hadj-Taieb. "Numerical modelling of hydrogen-natural gas mixtures flows in looped networks." Journal of Petroleum Science and Engineering 159 (November 2017): 532–41. http://dx.doi.org/10.1016/j.petrol.2017.09.063.

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Elaoud, Sami, and Ezzeddine Hadj-Taïeb. "Transient flow in pipelines of high-pressure hydrogen–natural gas mixtures." International Journal of Hydrogen Energy 33, no. 18 (September 2008): 4824–32. http://dx.doi.org/10.1016/j.ijhydene.2008.06.032.

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32

Shi, Zhuofan, Kristian Jessen, and Theodore T. Tsotsis. "Impacts of the subsurface storage of natural gas and hydrogen mixtures." International Journal of Hydrogen Energy 45, no. 15 (March 2020): 8757–73. http://dx.doi.org/10.1016/j.ijhydene.2020.01.044.

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HUANG, Z., Y. ZHANG, K. ZENG, B. LIU, Q. WANG, and D. JIANG. "Measurements of laminar burning velocities for natural gas–hydrogen–air mixtures." Combustion and Flame 146, no. 1-2 (July 2006): 302–11. http://dx.doi.org/10.1016/j.combustflame.2006.03.003.

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34

Seeburg, Dominik, Dongjing Liu, Radostina Dragomirova, Hanan Atia, Marga-Martina Pohl, Hadis Amani, Gabriele Georgi, Stefanie Kreft, and Sebastian Wohlrab. "Low-Temperature Steam Reforming of Natural Gas after LPG-Enrichment with MFI Membranes." Processes 6, no. 12 (December 12, 2018): 263. http://dx.doi.org/10.3390/pr6120263.

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Low-temperature hydrogen production from natural gas via steam reforming requires novel processing concepts as well as stable catalysts. A process using zeolite membranes of the type MFI (Mobile FIve) was used to enrich natural gas with liquefied petroleum gas (LPG) alkanes (in particular, propane and n-butane), in order to improve the hydrogen production from this mixture at a reduced temperature. For this purpose, a catalyst precursor based on Rh single-sites (1 mol% Rh) on alumina was transformed in situ to a Rh1/Al2O3 catalyst possessing better performance capabilities compared with commercial catalysts. A wet raw natural gas (57.6 vol% CH4) was fully reformed at 650 °C, with 1 bar absolute pressure over the Rh1/Al2O3 at a steam to carbon ratio S/C = 4, yielding 74.7% H2. However, at 350 °C only 21 vol% H2 was obtained under these conditions. The second mixture, enriched with LPG, was obtained from the raw gas after the membrane process and contained only 25.2 vol% CH4. From this second mixture, 47 vol% H2 was generated at 350 °C after steam reforming over the Rh1/Al2O3 catalyst at S/C = 4. At S/C = 1 conversion was suppressed for both gas mixtures. Single alkane reforming of C2–C4 showed different sensitivity for side reactions, e.g., methanation between 350 and 650 °C. These results contribute to ongoing research in the field of low-temperature hydrogen release from natural gas alkanes for fuel cell applications as well as for pre-reforming processes.

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35

Escalante, Edwin Santiago Rios, and João Andrade De Carvalho Junior. "Interchangeability analysis from natural gas to natural gas/hydrogen mixtures: The wobbe index as a first approximation." Rio Oil and Gas Expo and Conference 22, no. 2022 (September 26, 2022): 217–18. http://dx.doi.org/10.48072/2525-7579.rog.2022.217.

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Kizek, Ján, Augustín Varga, Gustáv Jablonský, and Ladislav Lazić. "The Effect of Adding Hydrogen to Natural Gas on Flue Gas Emissivity." Advances in Thermal Processes and Energy Transformation 4, no. 4 (2021): 64–69. http://dx.doi.org/10.54570/atpet2021/04/04/0064.

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The aim of the article is to analyse the impact of adding hydrogen to natural gas. The main goal is to analyze the influence of the increase of hydrogen during the combustion of the gas-air mixture on the emissivity of flue gases in the combustion chamber, applying calculation methods from known relations that can be used in the creation of mathematical models. The created mathematical model simulates the increase in the amount of hydrogen in natural gas. The results are graphical representations of the courses of the selected parameters depending on the increase of the hydrogen content in the mixture. The increase of hydrogen in the fuel mixture confirms a significant effect on the emissivity of exhaust gases, especially from 60% hydrogen content. Moreover, with already 45% of hydrogen in the fuel mixture, the composition and volume of the exhaust gases also changes significantly.

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Bölkény, Ildikó, Domonkos Horváth, and Marianna Vadászi. "Hydration of natural gas hydrogen mixture test equipment." Multidiszciplináris tudományok 11, no. 5 (2021): 145–50. http://dx.doi.org/10.35925/j.multi.2021.5.14.

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The use of hydrogen as an energy source is advantageous because its combustion processes only produce water vapor, but not carbon dioxide. This excess energy can be stored in underground gas storage facilities, where it is delivered mixed with natural gas. In gas- and oil industry the formation of hydrate crystals can cause significant damages. A huge amount of hydrate crystal is formed, it can cause hydrate plugs in the pipeline. Like natural gas, hydrate formation occurs in the case of a natural gas-hydrogen mixture. The paper presents a method which can be used to study hydrate formation in natural gas-hydrogen mixture.

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Luzzo, Irene, Filippo Cirilli, Guido Jochler, Alessio Gambato, Jacopo Longhi, and Gabriele Rampinini. "Feasibility study for the utilization of natural gas and hydrogen blends on industrial furnaces." Matériaux & Techniques 109, no. 3-4 (2021): 306. http://dx.doi.org/10.1051/mattech/2022006.

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In the deep steel industry decarbonization, green hydrogen plays a pivotal role as alternative energy to replace natural gas and carbon bearing materials. In this frame, technical aspects and in general criticalities relevant to the use of mixtures of hydrogen and natural gas in industrial processes were investigated: in particular its effect was analyzed on employ of existing industrial burners for treatment furnace and on oxidability and descaling susceptibility of forged material as Grade F22V and Inconel® 625. The experimental campaign on burner using blends with 30% and 50%vol. of hydrogen in natural gas highlighted that it is possible to ignite the burner for both mixtures, but that the burner is more stable with the 30%vol. of hydrogen in natural gas. The detected emissions of nitrogen oxides compared to the natural gas increase up to 15%. The results indicated that selected high speed burner should be used in industrial plant with a 30% of hydrogen in volume with no need of hardware modifications. The oxidation investigation on atmospheres deriving from the combustion of 100% of hydrogen, at 1230 °C, showed a moderate scale increase up to 14% for F22V grade and 8% for Inconel® 625. This increase of scale growth has not detrimental effect on the scale removability. For the selected reference industrial scenario, the burner was positively tested in industrial furnace with a 30% of hydrogen in volume with no need of hardware modifications. Moderate scale growth was observed, but with no detrimental effect on the scale removability. Moreover, the H2 addition allows to get CO2 reductions, without any noticeable drawback on other process parameters or product quality for this industrial scenario.

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Rahman, Mohammad Nurizat, Norshakina Shahril, Suzana Yusup, and Ismail Shariff. "Hydrogen Co-Firing Characteristics in a Single Swirl Burner: A Numerical Analysis." IOP Conference Series: Materials Science and Engineering 1257, no. 1 (October 1, 2022): 012020. http://dx.doi.org/10.1088/1757-899x/1257/1/012020.

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Abstract Hydrogen is gaining traction as an energy carrier in the decarbonisation and net-zero-emissions agenda. Because hydrogen is a clean energy carrier, increasing the percentage of hydrogen in natural gas mixtures aids in the decarbonisation initiatives. Hence, the flame characteristics of the natural gas mixtures, together with hydrogen are explored in the current study through a numerical assessment of a single swirl burner (swirl number, SN 0.78) since the said burner is widely used in gas turbine (GT) combustors. The baseline CFD and experimental cases referred to natural gas compositions primarily composed of methane (CH4). The results reveal that the CFD model can effectively represent the swirling component of the flame as seen in the experiment. A 5% hydrogen addition had virtually no effect on the swirling flame structure, as shown by qualitative evaluation of hydroxyl (OH) behaviour and flame temperature in comparison to the baseline methane flame. Despite this, the addition of hydrogen has increased the OH radical pool during combustion, causing a small change in flame temperature. Overall, the novelty of the current research is the opportunity to fire 5% hydrogen in a CH4-dominated GT combustor without any major retrofitting operations, as the study discovered that 5% hydrogen in a pure CH4 stream has a minor affect. However, more research is needed to properly capture the flame structure and strain for assessing transient-related phenomena like flashback and blow off by increasing the hydrogen proportion and using a higher accuracy turbulence model.

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Taymarov, M. A., R. V. Akhmetova, Ye G. Chiklyayev, Y. V. Lavirko, E. A. Akhmetov, and A. O. Garifullina. "Study of the speed of flame distribution in the combustion of methane-hydrogen fractions." E3S Web of Conferences 124 (2019): 05065. http://dx.doi.org/10.1051/e3sconf/201912405065.

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At present, natural gas of the Urengoyskoye field is burned in boilers of thermal power plants (TPP) to generate electricity. At the same time, refineries and petrochemical plants deepen the processing of fossil liquid hydrocarbons. The final product of processing is not only motor fuels, ethylene glycols, plastics, accompanying inert gases such as argon, but also a large amount of combustible secondary gaseous mixtures of the methane series. These mixtures contain a wide array of combustible components. Among them there is the methane-hydrogen fraction, which is characterized by a fairly high hydrogen content. A distinctive feature of the use of hydrogen as a fuel is the high rate of flame propagation and the relatively low heat of combustion [1, p.6-8]. The methane-hydrogen fraction due to the volatility of the composition and a wide range of changes in the heat of combustion was recently used in refineries for their own needs as an insignificant additive to combusted natural gas in process furnaces [2-5]. If the methane-hydrogen fraction was not utilized as a fuel in these furnaces, it was burned in flares. Due to the increase in oil refining volumes and the increase in the amount of methane-hydrogen fraction produced, it became realistic to use this gaseous fraction as the main fuel for power boilers of thermal power plants located near petrochemical plants. In the near future, it is planned to use the methane-hydrogen fraction as an additive to the natural gas for 20 power steam boilers of the Nizhnekamsk CHP-1 with a total thermal capacity of 6000 MW. The supplier of the methane-hydrogen fraction is the TAIF NK oil refineries. Depending on the technology of oil refining, the hydrogen content in the methane-hydrogen fraction ranges from 10 to 27% (by weight). The concentration limits of hydrogen ignition in a mixture with air have been experimentally studied by many researchers [6–8] mainly during bench testing or inside laboratories. A feature of the oxidation of hydrogen by air oxygen is the fact that there is a difference between the spread of the flame in limited volumes and in large volumes of the furnace space of energy boilers [9]. In small volumes, when the flame front collides with the wall, oxidation reactions are interrupted, and this does not occur in large volumes. Therefore, the study of flame propagation speed and concentration limits of ignition of methanehydrogen fractions mixed with air in relation to the conditions of furnace volumes of power boilers is relevant. In this work using the in-house software [2-5] calculations were made to determine the burning rate for various compositions of mixtures of methane-hydrogen fractions (MHF) with Urengoi natural gas. It was found that the flame propagation rate of the MHF, compared with hydrogen (see Table 2), decreases 1.76 times. For a mixture of the MHF with Urengoi gas with thermal fractions of the MHF of 12% and 25%, the flame propagation rate increases, respectively, 1.4 times and 1.78 times compared with burning pure Urengoi gas.

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41

Ji, Min, Haiyan Miao, Qi Jiao, Qian Huang, and Zuohua Huang. "Flame Propagation Speed of CO2Diluted Hydrogen-Enriched Natural Gas and Air Mixtures." Energy & Fuels 23, no. 10 (October 15, 2009): 4957–65. http://dx.doi.org/10.1021/ef900458r.

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42

Capurso, Tommaso, Vito Ceglie, Francesco Fornarelli, Marco Torresi, and Sergio M. Camporeale. "CFD analysis of the combustion in the BERL burner fueled with a hydrogen-natural gas mixture." E3S Web of Conferences 197 (2020): 10002. http://dx.doi.org/10.1051/e3sconf/202019710002.

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The regulatory restrictions, currently acting, impose a significant reduction of the Greenhouse Gas (GHG) emissions. After the coal-to-gas transition of the last decades, the fossil fuel-to-renewables switching is the current perspective. However, the variability of energy production related to Renewable Energy Sources requires the fundamental contribution of thermal power plants in order to guaranty the grid stability. Moving toward a low-carbon society, the industry is looking at a reduction of high carbon content fuels, pointing to Natural Gas (NG) and more recently to hydrogen-NG mixtures. In this scenario, a preliminary study of the BERL swirled stabilized burner is carried out in order to understand the impact of blending natural gas with hydrogen on the flame morphology and CO emissions. Preliminary 3D CFD simulations have been run with the purpose to assess the best combination of combustion model (Non Premixed and Partially Premixed Falmelets), turbulence model (Realizable k ɛ and the Reynolds Stress equation model) and chemical kinetic mechanism (GriMech3.0, GriMech 1.2 and Frassoldati). The numerical results of the BERL burner fueled with natural gas have been compared with experimental data in terms of flow patterns, radial temperature profiles, O2, CO and CO2 concentrations. Finally, a 30% hydrogen in natural gas mixture has been considered, keeping fixed the thermal power output of the burner and the global equivalence ratio.

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43

Mohammad Nurizat Rahman, Norshakina Shahril, and Suzana Yusup. "Hydrogen-Enriched Natural Gas Swirling Flame Characteristics: A Numerical Analysis." CFD Letters 14, no. 7 (July 17, 2022): 100–112. http://dx.doi.org/10.37934/cfdl.14.7.100112.

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Increasing the amount of hydrogen (H2) in natural gas mixtures contributes to gas turbine (GT) decarbonisation initiatives. Hence, the swirling flame characteristics of natural gas mixtures with H2 are investigated in the current work using a numerical assessment of a single swirl burner, which is extensively employed in GT combustors. The baseline numerical and experimental cases pertained to natural gas compositions largely consisting of methane (CH4). The results show that the numerical model adequately describes the swirling component of the flame observed in the experiment. Altogether, the findings show that hydroxyl (OH) radical levels increase in H2-enriched CH4 flames, implying that greater OH pools are responsible for the change in flame structure caused by considerable H2 addition. The addition of 10 % H2 is predicted to raise the peak flame temperature by 4 % compared to the baseline CH4 flame. Therefore, adding 10 % H2 into a GT combustor without any flowrate tuning raises the risk of turbine material deterioration and increased thermal NOx emission. Due to the lower volumetric Lower Heating Value (LHV) of H2, which needs a higher volumetric fuel flow rate than burning natural gas/CH4 at the same thermal output, the addition of 2 % H2 is predicted to reduce the peak flame temperature by 4 % compared to the baseline CH4 flame. Hence, if 2 % H2 is fed into a GT combustor without any flowrate tuning, the required load may not be obtained. When compared to the baseline CH4 case, the addition of 5 % H2 is predicted to provide almost identical peak flame temperature, which can be postulated that the addition of 5 % H2 can produce roughly the same peak flame temperature as the pure CH4 flame because the Wobbe Index is comparable. Therefore, it reveals that incorporating 5 % H2 in the natural gas-fired GT combustor with nearly no modification is viable. More research, however, is required to fully capture the flame structure and strain for assessing transient-related phenomena such as flashback and blow off by raising the H2 proportion and utilising a higher precision turbulence model.

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44

De Robbio, Roberta. "Innovative combustion analysis of a micro-gas turbine burner supplied with hydrogen-natural gas mixtures." Energy Procedia 126 (September 2017): 858–66. http://dx.doi.org/10.1016/j.egypro.2017.08.291.

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45

Budak, Paweł, and Tadeusz Szpunar. "Dobór wydajności gazów propan-butan dodawanych w celu wspomagania efektywnego spalania gazu ziemnego niskometanowego z użyciem flary." Nafta-Gaz 77, no. 1 (January 2021): 26–32. http://dx.doi.org/10.18668/ng.2021.01.04.

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The paper discusses the problems related to the burning of gas mixtures containing flammable and non-flammable gases using a flare. Before being burned, such a gas mixture must be “enriched” with other flammable gases before it can be directed to the flare. In the case of some Polish gas reservoirs such as Cychry or Sulęcin, the composition of the gas mixture doesn’t make it possible to burn it using the flare because the content of inflammable components is too high and the gas mixture is inflammable. The gas from the reservoirs mentioned above contains above 90 percent of nitrogen and small percentages of flammable components. Sometimes, besides nitrogen, the gas mixture contains other inflammable gases like carbon dioxide, helium, and oxygen. Usually, the propane/butane is used for that purpose. The possibility of burning the gas mixture using the flare is particularly important if the toxic gases are present in the mixture – hydrogen sulfide in particular. The propane/butane gases are added to the stream of gas mixture meant for burning using a special appliance. The typical arrangement of a gas-burning installation (i.e. the flare) is shown and the destination of its components is discussed. The empirical formula is provided which allows us to recognize if the gas mixture is flammable or not. The composition of the gas mixture must be known to calculate the propane/butane flow rate, including percentages of flammable and inflammable components. The algorithm constructed for calculating the propane/butane flow rate is presented, which must be maintained to assure the flammability of the gas mixture destined for burning using the flare. The results of the calculations for four gas mixtures from the Polish gas reservoirs are provided. The presented method of determining the flammability of gas mixtures (or its inability to be burned) and the flow rate of the propane/butane mixture required for complete combustion is based on empirical relationships, which are provided in the paper and may be helpful in planning the assisted combustion of low methane gases (not suitable for further use) using a flare.

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Khannanov, Maksim N., Alexander B. Van'kov, Andrei A. Novikov, Anton P. Semenov, Pavel A. Gushchin, Sergei I. Gubarev, Vadim E. Kirpichev, Elena N. Morozova, Leonid V. Kulik, and Igor V. Kukushkin. "Analysis of Natural Gas Using a Portable Hollow-Core Photonic Crystal Coupled Raman Spectrometer." Applied Spectroscopy 74, no. 12 (October 9, 2020): 1496–504. http://dx.doi.org/10.1177/0003702820915535.

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The low accessibility of natural gas fields and transporting pipelines requires portable online analyzers of the composition of natural gas, ensuring nearly chromatographic precision and capable of in situ analysis of a wide range of gases, including infrared-inactive ones (hydrogen, oxygen, nitrogen, chlorine). We have developed an express method of gas analysis meeting all the requirements for analysis of natural gas and its derivative mixtures using a portable 532 nm Raman spectrometer rigidly connected to a hollow-core crystal photonic fiber.

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47

Mitu, Maria, Domnina Razus, and Volkmar Schroeder. "Laminar Burning Velocities of Hydrogen-Blended Methane–Air and Natural Gas–Air Mixtures, Calculated from the Early Stage of p(t) Records in a Spherical Vessel." Energies 14, no. 22 (November 12, 2021): 7556. http://dx.doi.org/10.3390/en14227556.

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The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determined in accordance with EN 15967, by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen, rH, follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV, as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures, the rate of heat release, and the concentration of active radical species in the flame front and contribute, thus, to LBV variation.

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48

Chríbik, Andrej, Marián Polóni, Ján Lach, and Branislav Ragan. "THE EFFECT OF ADDING HYDROGEN ON THE PERFORMANCE AND THE CYCLIC VARIABILITY OF A SPARK IGNITION ENGINE POWERED BY NATURAL GAS." Acta Polytechnica 54, no. 1 (February 28, 2014): 10–14. http://dx.doi.org/10.14311/ap.2014.54.0010.

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This paper deals with the influence of blending hydrogen (from 0 to 50% vol.) on the parameters and the cyclic variability of a Lombardini LGW702 combustion engine powered by natural gas. The experimental measurements were carried out at various air excess ratios and at various angles of spark advance, at an operating speed of 1500 min<sup>−1</sup>. An analysis of the combustion pressure showed that as the proportion of hydrogen in the mixture increases, the maximum pressure value also increases. However, at the same time the cyclic variability decreases. Both the ignition-delay period and the period of combustion of the mixture become shorter, which requires optimization of the spark advance angle for various proportions of hydrogen in the fuel. The increasing proportion of hydrogen extends the flammability limit to the area of lean-burn mixtures and, at the same time, the coefficient of cyclic variability of the mean indicated pressure decreases.

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Fan, J., Y. Wang, J. Shi, Y. Shi, H. Cao, and N. Cai. "Influences of Hydrogen-Natural Gas Mixtures on The Performance of an Internal Reforming Solid Oxide Fuel Cell Unit: A Simulation Study." Journal of The Electrochemical Society 169, no. 4 (April 1, 2022): 044511. http://dx.doi.org/10.1149/1945-7111/ac6327.

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Blending hydrogen into natural gas grid can effectively reduce carbon emissions and promote the development of the hydrogen economy. Utilizing hydrogen-natural gas mixtures through internal reforming solid oxide fuel cells (SOFCs) can convert the chemical energy of the fuels direct into electricity, which is a promising technology for combined heat and power systems. In this study, a three-dimensional model for an internal reforming solid oxide fuel cell unit is developed coupling chemical and electrochemical reactions, mass, momentum and heat transfer processes. The model is validated by both the patterned anode experiments and the button cell experiments with porous electrodes. The distributions of temperature, gas compositions, and current density between pure methane and 30% hydrogen addition are simulated and compared. The influences of the hydrogen addition on the performance of the SOFC unit are further studied by changing the hydrogen blending ratio. The simulation results show that the addition of hydrogen affects the coupling of the endothermic reforming reactions and exothermic electrochemical reactions, which leads to improved temperature uniformity and higher current density of the SOFC unit compared with pure methane feeding.

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Jia, Wenlong, Qingyang Ren, Hao Zhang, Ming Yang, Xia Wu, and Changjun Li. "Multicomponent leakage and diffusion simulation of natural gas/hydrogen mixtures in compressor plants." Safety Science 157 (January 2023): 105916. http://dx.doi.org/10.1016/j.ssci.2022.105916.

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Journal articles on the topic 'Natural gas/hydrogen mixtures'

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