Jin Guo, Zexuan Yang, Liang Mei, Shikai Huang, Haozhe Wang
{"title":"Combined effects of ignition position and hydrogen ratio on vented CH4/H2/air explosions","authors":"Jin Guo, Zexuan Yang, Liang Mei, Shikai Huang, Haozhe Wang","doi":"10.1016/j.jlp.2024.105356","DOIUrl":null,"url":null,"abstract":"<div><p>Experiments on the effects of ignition position and hydrogen ratio (χ) on the explosions of CH<sub>4</sub>/H<sub>2</sub>/air mixtures were experimentally investigated in a vented cylindrical vessel. Relevant experiments were conducted utilizing ignition sources situated at the rear (rear ignition), the center of the vessel (central ignition), or near the vent (front ignition) with χ varying from 0 to 1.0. Two types of cellular structures on the flame surface, owing to the diffusional-thermal instability and acoustically enhanced combustion, respectively, were observed, and the latter resulted in acoustic oscillations of the overpressure within the vessel and a unique overpressure peak <span><math><mrow><msub><mi>p</mi><mn>2</mn></msub></mrow></math></span> with amplitude sensitive to both ignition position and χ. The effects of ignition position and χ on the build-up of the internal pressure were not significant when χ ≤ 0.15. The maximum explosion overpressure in the vessel (<span><math><mrow><msub><mi>p</mi><mi>max</mi></msub></mrow></math></span>) under the explosions of rear and central ignitions (RI and CI) increased monotonically as χ was increased from 0.3 to 1.0, but a nonmonotonic trend was found in the explosions of front ignition (FI). CI could be regarded as the worst-case scenario when 0.45≤χ ≤ 1.0 except for χ = 0.7, because FI resulted in the highest <span><math><mrow><msub><mi>p</mi><mi>max</mi></msub></mrow></math></span> at χ = 0.7. A pressure peak outside the vent (<span><math><mrow><msub><mi>p</mi><mrow><mi>e</mi><mi>x</mi><mi>t</mi></mrow></msub></mrow></math></span>) caused by the combustion expansion of the combustible cloud could be distinguished when χ ≥ 0.45 in the explosions of RI and CI. The amplitude of <span><math><mrow><msub><mi>p</mi><mrow><mi>e</mi><mi>x</mi><mi>t</mi></mrow></msub></mrow></math></span> increased with an increase in χ. Rear ignition always led to the highest <span><math><mrow><msub><mi>p</mi><mrow><mi>e</mi><mi>x</mi><mi>t</mi></mrow></msub></mrow></math></span> when χ > 0.6.</p></div>","PeriodicalId":16291,"journal":{"name":"Journal of Loss Prevention in The Process Industries","volume":null,"pages":null},"PeriodicalIF":3.6000,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Loss Prevention in The Process Industries","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0950423024001141","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Experiments on the effects of ignition position and hydrogen ratio (χ) on the explosions of CH4/H2/air mixtures were experimentally investigated in a vented cylindrical vessel. Relevant experiments were conducted utilizing ignition sources situated at the rear (rear ignition), the center of the vessel (central ignition), or near the vent (front ignition) with χ varying from 0 to 1.0. Two types of cellular structures on the flame surface, owing to the diffusional-thermal instability and acoustically enhanced combustion, respectively, were observed, and the latter resulted in acoustic oscillations of the overpressure within the vessel and a unique overpressure peak with amplitude sensitive to both ignition position and χ. The effects of ignition position and χ on the build-up of the internal pressure were not significant when χ ≤ 0.15. The maximum explosion overpressure in the vessel () under the explosions of rear and central ignitions (RI and CI) increased monotonically as χ was increased from 0.3 to 1.0, but a nonmonotonic trend was found in the explosions of front ignition (FI). CI could be regarded as the worst-case scenario when 0.45≤χ ≤ 1.0 except for χ = 0.7, because FI resulted in the highest at χ = 0.7. A pressure peak outside the vent () caused by the combustion expansion of the combustible cloud could be distinguished when χ ≥ 0.45 in the explosions of RI and CI. The amplitude of increased with an increase in χ. Rear ignition always led to the highest when χ > 0.6.
期刊介绍:
The broad scope of the journal is process safety. Process safety is defined as the prevention and mitigation of process-related injuries and damage arising from process incidents involving fire, explosion and toxic release. Such undesired events occur in the process industries during the use, storage, manufacture, handling, and transportation of highly hazardous chemicals.