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The explosion risk of ethylene (C 2 H 4 ) seriously hinders safe development of its production and processing. To reduce the harm caused by C 2 H 4 explosion, an experimental study was conducted to assess the explosion inhibition characteristics of KHCO 3 and KH 2 PO 4 powders. The experiments were conducted based on the explosion overpressure and flame propagation of the 6.5% C 2 H 4 -air mixture in a 5 L semi-closed explosion duct. Both the physical and chemical inhibition characteristics of the inhibitors were mechanistically assessed. The results showed that the 6.5% C 2 H 4 explosion pressure ( P ex ) decreases by increasing the concentration of KHCO 3 or KH 2 PO 4 powder. The inhibition effect of KHCO 3 powder on the C 2 H 4 system explosion pressure was better than that of the KH 2 PO 4 powder under similar concentration conditions. Both powders significantly affected the flame propagation of the C 2 H 4 explosion. Compared with KH 2 PO 4 powder, KHCO 3 powder had a better inhibition effect on the flame propagation speed, but its ability to reduce the flame luminance was less than KH 2 PO 4 powder. Finally, the inhibition mechanism(s) of KHCO 3 and KH 2 PO 4 powders were revealed based on the powders' thermal characteristics and gas-phase reaction., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Garbage and biomass contain more chlorine, which reacts with H 2 to form HCl gas during combustion or gasification, resulting in corrosion of metal walls. In this paper, based on the chlorine mechanism in Ansys Chemkin-Pro, the laminar combustion characteristics of H 2 /Cl 2 are simulated with different diluents CO 2 /N 2 under an initial temperature of 298 K, equivalence ratio range of 0.6-1.4, and initial pressure of 0.1-0.5 MPa. The results show that the laminar burning velocity of H 2 /Cl 2 decreases significantly with the increase of dilution gas ratio, and the effect of diluent CO 2 is more significant than that of N 2 . Due to the dilution effect, the fuel and oxidation components are reduced. Through sensitivity analysis, reaction R2: Cl + H 2 = HCl + H is the main reaction of HCl formation. On improving the initial pressure, the laminar burning velocity is slightly lowered, and the thermal diffusivity of the fuel mixture increases with the increase of the initial pressure. According to the sensitivity analysis of the velocity, reactions R2, R9, and R10 are the main reactions that affect the laminar burning velocity, and the product HCl will be generated with a delay with the increase of the initial pressure., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The composition of low calorific value synthesis gas varies greatly depending on the raw material and processing technology, which makes the combustion extremely complicated. The three mechanisms of the GRI-Mech 3.0, Li-Model, and FFCM-Mech are used to numerically simulate CH 4 /CO/H 2 /N 2 air premixed combustion by using ANSYS CHEMKIN-PRO. The numerical simulation is the calculation of laminar flame velocity and adiabatic flame temperature at an initial temperature of 298 K, an equivalence ratio of 0.6-1.4, and an initial pressure of 0.1-0.5 MPa, discussing through thermodynamics and chemical kinetics. The formation of NO X , H, and OH radicals by fuel composition was analyzed. The result shows that the concentrations of H, O, and OH radicals have a positive effect on laminar flame velocity. The combustion reaction of H 2 is higher than that of CH 4 and CO; with the increase of N 2 content, the priority is higher. The thermal diffusivity of flame under different equivalence ratios is affected by inert gas, which affects adiabatic combustion temperature and laminar combustion velocity. In thermal kinetics and chemical kinetics, CH 4 has more influence on combustion temperature than CO, while laminar flame velocity is relatively low. Under the change of initial pressure, the laminar combustion flux increases to the initial pressure and the laminar combustion velocity decreases to the increase in pressure. Reactions H + O 2 = O + OH, HO 2 + H = 2OH, and CH 3 + HO 2 = OH + CH 3 O are mainly due to change in the concentration of O, H, and OH radicals., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

In this paper, the flame propagation characteristics and overpressure oscillation characteristics of CH 4 explosion were studied under different ignition positions (IPs) and oxygen enrichment conditions in a half-open tube. The distances between the IP and the closed end of the tube are 0, 250, 500, and 750 mm. The oxygen enrichment coefficient (φ) values used in the experiment are 0.21, 0.3, and 0.4. The experimental results show that the IP and oxygen enrichment coefficient have an important influence on the flame structure and overpressure oscillation. Only when the oxygen enrichment coefficient φ = 0.21, a tulip flame will be formed. The IP close to the outlet can make the air participate in the combustion more quickly. With the increase of the oxygen enrichment coefficient, the combustion-induced rapid phase transition phenomenon is more likely to occur, and the maximum overpressure value and the overpressure rise rate of flame will increase. It is worth noting that after increasing the oxygen enrichment coefficient, the IP has less influence than the oxygen enrichment coefficient on the overpressure rise rate., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)