Evaluation of the air-demand, flame height, and radiation from low-profile flare tips using ISIS-3D

Low-profile flare fields pose significant design challenges including elongated flames, adequate air supply to burner tips located on inner rows and high radiation flux from the flame to the surrounding wind fence. Recent work completed by engineers at Alion Science and Technology for Zeeco, Inc. has focused on analyzing the performance of a proprietary burner tip used in large low profile gas flares having upwards of 400 burner tips packed together into a staged piping configuration surrounded by a specially designed wind fence. This paper presents results from the CFD analysis of this gas flare and illustrates the capability of the CFD tool to simulate soot formation, radiant flux, flame shape, and flame height for industrial scale low-profile flare fields. This work was completed in conjunction with flare testing where ethylene was fired through the burner tips. Data collected during these flare tests included video, radiant flux, and sound. Test results were used to calibrate the combustion model and to validate CFD predictions of flame height and air demand. Based on this, predicted flame height and air demand were provided for two full flare field cases. In addition, estimates of radiant flux to the surrounding wind fence were provided.