Detonability of Natural Gas-Air Mixtures


Direct initiation experiments were carried out in a 105. cm diameter tube to study detonation properties and evaluate the detonability limits for mixtures of natural gas (NG) with air. The natural gas was primarily methane with 1.5-1.7% of ethane. A stoichiometric methane-oxygen mixture contained in a large plastic bag was used as a detonation initiator. Self-supporting detonations with velocities and pressures close to theoretical CJ values were observed in NG-air mixtures containing from 5.3% to 15.6% of NG at atmospheric pressure. These detonability limits are wider than previously measured in smaller channels, and close to the flammability limits. Detonation cell patterns recorded near the limits vary from large cells of the size of the tube to spiral traces of spin detonations. Away from the limits, detonation cell sizes decrease to about 20. cm for 10% NG, and are consistent with existing data for methane-air mixtures obtained in smaller channels. Observed cell patterns are very irregular, and contain secondary cell structures inside primary cells and fine structures inside spin traces. © 2011.


Mining Engineering

Keywords and Phrases

Detonability Limits; Detonation Cells; Methane-Air

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Document Type

Article - Journal

Document Version


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© 2012 Elsevier, All rights reserved.

Publication Date

01 Jan 2012