Overview of flaring efficiency studies

Several studies over the past 20 years have evaluated flare efficiencies. These include major flare research programs by the U.S. EPA, the Alberta Research Council, and the University of Alberta. Other work includes a CMA study; surveys of operating flares by BP/Statoil, the German Aerospace Centre and Shell in Europe, and Shell Nigeria; and a multi-year PERF study of external combustion. These studies have consistently shown that appropriately designed and operated flares are highly efficient, converting 98-99.5% or more of the hydrocarbon feed to carbon dioxide and water. However, in certain situations, particularly cases of incomplete liquid knock-out, low BTU flare gas, or high wind conditions, the efficiency can be lower. The Alberta Research Council found efficiencies as low as 62% for unpiloted field pipe flares, with no flame stabilization or wind protection, subjected to liquid hydrocarbon carryover.