Scaling relations for flare interactions, flame lengths, and crosslighting requirements in large flare fields

Flare fields typically consist of many closely-spaced flares arranged in parallel rows. Each flare in the field produces an axisymmetric buoyant jet flame that for a limited vertical distance develops essentially independent of the other flames in the field. However, at a distance above the flare tips determined by the flare-to-flare spacing s, adjacent flames in the same row merge to form a planar buoyant jet flame. At a further distance determined by the row-to-row spacing S, the planar flames formed from adjacent rows then merge into a single flame. The merging in each row and between rows allows for crosslighting of flares in the field. These interactions, however, significantly complicate prediction of key properties of the resulting flames, including entrainment and mixing rates of the merged flames and the resulting overall flame height L. These aspects of flare fields differ fundamentally and substantially from those of a single flare. Of central importance to flare field design are the combined effects of the flare firing rate and the spacing parameters s and S on the crosslighting ability and the overall flame height. This paper develops fundamental scaling relations for the individual and merged flames in a flare field to allow assessment of flare field performance over a wide range of design and operating parameters, and allow optimal designs that minimize the flare field area and overall flame height.