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Hydrogen flare stack diffusion flames: low and high flow stabilities, burning rates, dilution limits, temperatures and wind effects.
Grumer-J; Strasser-A; Singer-JM; Gussey-PM; Rowe-VR
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 7457, 1970 Jan; :1-34
A laboratory-scale hydrogen safety study which determined several combustion characteristics of hydrogen diffusion flames is presented. Experiments show that ambient air may enter the top of a hydrogen flare stack when the hydrogen flow is low. A new concept, supported by photographic evidence, predicts that diffusion flames burning in air on a wide, upright pipe (stack) and fed with slow, upward flows of buoyant gas will induce a downward flow of air along the walls of the pipe that can support combustion within the pipe. Predicted flamedip limits agree roughly with experimental values determined on 6-, 12-, and 18-inch-diameter stacks and increase with increasing stack diameter. Measurements were made of the limiting flow at which a hydrogen diffusion flame blows out in still air. Temperatures of larger hydrogen diffusion flames up to about 3,600 F were observed, but the most representative value appears to be about 2,600 F. It was found that crosswinds do not strip significant amounts of unburned hydrogen from its diffusion flame and that water-cooled flare stacks are not likely to be damaged when flame is blown back into them by opposing winds.
Hydrogen; Diffusion flames; Flashback; Combustion; Burning rate; Concentration; Chimneys; Fire hazards; Explosions; Liquid rocket propellants
IH; Report of Investigations
NTIS Accession No.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 7457
Page last reviewed: May 5, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division