The U.S. Environmental Protection Agency (EPA) has issued final New Source Performance Standards (NSPS) for certain heaters and flares at petroleum refineries. 77 Fed. Reg. 56,422 (9/12/2012). EPA established limits for these devices in June 2008, but stayed these provisions to consider petitions for review.
Lifting the stay on the definition of “flare,” the final rule takes effect November 13, 2012, and applies to petroleum refineries constructed or modified after May 14, 2007. In the revised rule, EPA changes the averaging time for nitrogen oxide (NOX) limits applicable to process heaters from a 24-hour rolling average to a 30-day rolling average. It also changes the NOX limits for natural draft process heaters to include, in addition to a 40 parts per million by volume (ppmv) limit, an alternative of 0.04 pounds per million BTU, unless the heaters have co-fired oil and gas burners. For forced draft process heaters, limits change from 40 ppmv to alternative limits of 60 ppmv or 0.06 pounds per million BTU. Forced and natural draft heaters with co-fired burners change from 40 ppmv to 150 ppmv weighted average based on oil at 0.40 pounds per million BTU and gas at 0.11 pounds per million BTU. For process heaters, the rule allows case-by-case approval of alternate emission standards in some circumstances.
For flares, the final rule distinguishes between a flare and a fuel gas combustion device, effectively limiting the prior definition of “flare.” It also adds to the list of connections that do not constitute flare modification and therefore do not trigger applicability of the NSPS. For fuel gas combustion devices, the rule retains a 162 ppmv hydrogen sulfide (H2S) limit as a three-hour average, but eliminates a 60 ppmv annual rolling average. The 2008 rule required new or modified flares to comply with the H2S limit at startup and with all other limits within one year. The revised rule, however, (i) extends the compliance time for non-H2S limits to three years, (ii) eliminates a flare system-wide flow limit of 250,000 cubic feet per day, (iii) revises the trigger requiring root cause analysis and corrective action for flare upsets or malfunctions, (iv) adds a reference method for continuous total reduced sulfur monitoring, and (v) eliminates the continuous monitoring requirement for infrequently used flares.