科研之友
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摘要
In the process of storage, transportation and use of clean energy such as natural gas and coal-bed methane, explosions often occur. The technology of inert gas explosion suppression based on CO2 and N-2 has always been the focus of scholars. The popularization of CO2 dilution natural gas technology to reduce NOx emission, as well as the utilization of landfill gas and biogas dominated by methane and CO2, makes the study on the explosive characteristics of methane and CO2 mixture appear to be particularly important. @@@ In order to study the coupling law of flame and pressure of methane/air explosion under the action of CO2. experiments of suppressing methane/air explosion with different volume fraction of CO2 were carried out in a square plexiglass duct. The influence of methane/air premixed gas explosion flame propagation and explosion pressure under different volume fraction of CO2, as well as the coupling between explosion flame and pressure, were analyzed. The results show that with the increase of CO2, the flame temperature. flame speed, explosion overpressure peak. and the time to reach the peak of overpressure all show a decreasing trend. CO2 affects the combustion reaction rate from three aspects of dilution, thermal diffusion and chemical kinetics. The reduction of combustion reaction rate leads to three types of flame structure evolution, namely "non-tulip" flame, "tulip" flame and "buoyancy" flame, and also leads to three types of explosion overpressure evolution. They are "three-peak structure and the second peak is the maximum peak", "three-peak structure and the first peak is the maximum peak" and "two-peak structure and the first peak is the maximum peak" respectively. During the formation of tulip flame, the flame structure dominates the flame propagation speed and explosion pressure.
