nvestigation of a combustion driven oscillation in a refinery flare. Part A: Full scale assessment

An assessment of the cause of an intermittent combustion-driven oscillation in a full-scale refinery flare is reported. When present, ambient sound pressure levels in excess of 100 dBA are generated. The oscillations began after the replacement of an old flare tip with one of a different design which required the use of non-standard components. The assessment included measurements of time resolved and integrated sound pressure in the ambient environment, and pressure in the fuel pipe and the air duct. Images obtained from video recorded from two directions are presented along with relevant process data. A review is also presented of the conditions under which the oscillations are inhibited or enhanced, and a comparison is made with another flare of similar design which does not exhibit an oscillation. The Strouhal numbers of the potential causes of flow oscillation and the wavelength of acoustic resonances in the supply pipes are calculated. The findings are then compared with related investigations found in the literature.