NSPS Revised For Nitric Acid Plants

EPA has finalized new source performance standards (NSPS) for nitric acid plants, effective August 14, 2012. The new standards include lowering the nitrogen oxides (NOx) emission limit for each nitric acid production unit (NAPU) that was built or modified after October 14, 2011. The rule also includes additional testing and monitoring requirements. NSPS are required under Clean Air Act section 111(b) and are issued for sources which cause or contribute significantly to air pollution. The NSPS must reflect the best system of emission reduction, or BSER, and EPA must assess whether a standard is achievable by the regulated industry.

The final rule reduced NOx emissions from 3.0 pounds of NOx per ton of 100 percent nitric acid produced (lb NOx/ton acid) to 0.50 lb NOx/ton acid as a 30 operating day emissions rate calculated each operating day based on the previous 30 operating days.

Although general provisions in 40 CFR Part 60 provide exceptions for periods of startup, shutdown, and malfunctions, the new final rules will not allow any exceptions to the emissions limits — even during startups and shutdowns. EPA says there is equipment available to address higher emissions during these periods, if that is a concern for a facility. Certain allowances and exceptions may still be made for malfunctions.

Although NAPUs emit another nitrogen compound known as nitrous oxide (N2O), considered a greenhouse gas (GHG), EPA's final rule does not address the compound. However, the Agency says it is in the process of gathering and analyzing data on GHG emissions from NAPUs that will allow it to continue working toward a proposal for GHG standards from nitric acid plants.


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