Experimental study on the flammability limits of natural gas/air mixtures at elevated pressures and temperatures

Li, Pengliang; Liu, Zhenyi; Li, Mingzhi; Huang, Pengcheng; Zhao, Yao; Li, Xuan; Jiang, Shukun

doi:10.1016/j.fuel.2019.115950

Cited by 37 publications

(17 citation statements)

References 30 publications

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“…With decreasing initial temperature, the maximum explosive pressure increased and the density of the flammable mixture increased [13]. The higher the initial pressure or temperature, the higher the upper flammable limit [14]. The flammable limit of the natural gas-air mixture at 20 MPa and 100 • C increased significantly from 4.95% to 15.51% at room temperature (0.1 MPa and 25 • C) to 2.87-64.40%.…”

Section: Introductionmentioning

confidence: 99%

Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor

et al. 2020

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To achieve the efficient utilization of low-concentration mine gas, reduce resource waste and alleviate environmental pollution, the high-temperature oxidation of low-concentration gas at a concentration range of 1.00% to 1.50%, which is directly discharged into the atmosphere during coal mine production, was carried out to recover heat for reuse. The gas oxidation equipment was improved for the heating process and the safety of low-concentration gas oxidation under a high-temperature environment was evaluated. The experimental results showed that the reactor could provide a 1000 °C high-temperature oxidation environment for gas oxidation after installing high-temperature resistant ceramics. The pressure variation curves of the reactor with air and different concentrations of gas were similar. Due to the thermal expansion, the air pressure slightly increased and then returned to normal pressure. In contrast, the low-concentration gas exhibited a stable pressure response in the high-temperature environment of 1000 °C. The outlet pressure was significantly greater than the inlet pressure, and the pressure difference between the inlet and outlet exhibited a trend to increase with the gas concentration. The minimum pressure difference was 4 kPa (air) and the maximum was 11 kPa (1.50% gas). The explosion limit varied with the temperature and the blend of oxidation products. The ratio of measured gas pressure to air pressure after oxidation was below the explosion criterion, indicating that the measured concentration of gas is still safe after the shift of the explosion limit, which provides a safe concentration range for the efficient use of low-concentration gas in the future.

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Section: Introductionmentioning

confidence: 99%

Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor

et al. 2020

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“…Air injection into oil reservoirs is an innovative technique for improving oil recovery, which can be used in various types of oil reservoirs, such as light oil reservoirs with low permeability and heavy oil reservoirs via in-situ combustion. , However, there are great concerns on the application of this technique mainly due to the safety and explosion of flammable natural gas and air mixtures at high-pressure and high-temperature conditions. The relevant literature on the subject includes very newly published paper . The flammability/explosion limits of flammable gases are important parameters to measure the possibility of the explosion of flammable gas under certain initial conditions, which defines the range of fuel concentrations for flame propagation to occur.…”

Section: Introductionmentioning

confidence: 99%

“…The relevant literature on the subject includes very newly published paper. 3 The flammability/explosion limits of flammable gases are important parameters to measure the possibility of the explosion of flammable gas under certain initial conditions, which defines the range of fuel concentrations for flame propagation to occur. The lower flammable limit (LFL) and upper flammable limit (UFL) are the minimum and maximum composition limits, respectively, which a flame can propagate.…”

Section: Introductionmentioning

confidence: 99%

Flammability and Explosion Characteristics of Methane in Oxygen-Reduced Air and Its Application in Air Injection IOR Process

et al. 2019

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Air injection into oil reservoirs has been widely applied in oilfields for improved oil recovery, while the safety of the process is of great concern due to the explosion of the mixtures of natural gas (mainly methane) and injected air at high pressure and high temperature. Oxygen-reduced air flooding (ORAF) has been proposed to eliminate the explosion risks. The combustion and flammability characteristics of methane–air mixtures at elevated pressure and temperature are also important for natural gas engines and air compressors. In this study, an experimental setup was used to measure the flammability limits and explosion energy of methane in oxygen-reduced air (ORA) at pressures up to 15 MPa and 373 K and compared with methane–air mixtures. The experimental results show that the flammability limits of methane in ORA can be significantly reduced or narrowed, which can reduce explosion risks. At high pressures, the low flammability limit of methane in ORA is reduced, and its upper flammability limit is increased, which follows a similar pattern with methane–air mixtures. The explosion energy of methane in ORA can be also greatly reduced due to the lack of oxygen. Finally, the explosion risks in applying the ORAF technique for improved oil recovery have been analyzed.

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“…To safely perform aerobic methane iodination, the reaction scale was decreased to <0.5 mL using a stop-flow microtubing (SFMT) reactor described by Wu and co-workers (Scheme c). , Flammable gas–air compositions were avoided by using high methane pressures. When the SFMT reactor was charged with methane (500 psi) and an air-saturated solution of TBACl and I 2 , subsequent photolysis generated iodomethane (10.5 equiv.…”

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confidence: 99%

A Metal-Free, Photocatalytic Method for Aerobic Alkane Iodination

et al. 2021

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Halogenation is an important alkane functionalization strategy, but O 2 is widely considered the most desirable terminal oxidant. Here, the aerobic iodination of alkanes, including methane, was performed using catalytic [ n Bu 4 N]Cl and light irradiation (390 nm). Up to 10 turnovers of CH 3 I were obtained from CH 4 and air, using a stop-flow microtubing system. Mechanistic studies using cyclohexane as the substrate revealed important details about the iodination reaction. Iodine (I 2 ) serves multiple roles in the catalysis: (1) as the alkyl radical trap, (2) as a precursor for the light absorber, and (3) as a mediator of aerobic oxidation. The alkane activation is attributed to Cl • derived from photofragmentation of the electron donor−acceptor complex of I 2 and Cl − . The kinetic profile of cyclohexane iodination showed that aerobic oxidation of I 3 − to produce I 2 in CH 3 CN is turnoverlimiting.

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Experimental study on the flammability limits of natural gas/air mixtures at elevated pressures and temperatures

Cited by 37 publications

References 30 publications

Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor

Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor

Flammability and Explosion Characteristics of Methane in Oxygen-Reduced Air and Its Application in Air Injection IOR Process

A Metal-Free, Photocatalytic Method for Aerobic Alkane Iodination

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