





Date:		May 2012

Subject:	Agrium North Bend Analyses
		Nitric Acid NSPS Review
      EPA Contract No. EP-D-11-084; Work Assignment No. 0-01  
        RTI Project No. 02103199.000.001

From:			Melissa Icenhour
							
To:			Nathan Topham
        OAQPS/SPPD/MICG (D243-02)
        U. S. Environmental Protection Agency
      Research Triangle Park, NC  27711


As described in the memo entitled Statistical Evaluation of CEMS Data to Determine the NOX Emission Standard (Updated Memo for Final Standard, the long term CEMS data showed a maximum 30 day emission rate of 0.41 lb NOX/ton acid for the Agrium North Bend plant. These emissions were calculated based on data from Agrium that startup and shutdown events occur on average about 3 to 4 hours per month. These periods make up an extremely small fraction of total operating time (i.e. 1% or less), but commenters indicated that these periods can occur more frequently for some facilities.

Some facilities may undergo more periods of startup and shutdown compared to the facilities for which we had emissions data. Even with an increase in the number of startup and shutdown periods, these periods still make up a very small fraction of total operating time. However, the EPA has performed hypothetical calculations on the CEMS data from the Agrium North Bend plant using the assumption that the number of periods of startup and shutdown are lower than other nitric acid plants. The number of startup/shutdown periods for Agrium North Bend was compared to the highest number of startup and shutdown periods reported through the Section 114 request. 

According to the information received in response to the Section 114 request, the highest number of hourly startup and shutdown periods per year was reported as 95 by the nitric acid plant in Coffeyville, Kansas. 

Doubling the 67 hourly startup and shutdown periods reported by Agrium North Bend to 134 hourly startup and shutdown periods places them above the highest number of startup and shutdown periods from any of our Section 114 respondents. The resulting maximum 30 day emission rate is 0.47 lb NOX/ton acid. See Figure 1.
Commenters also noted that the Agrium North Bend plant uses hydrogen peroxide injection (HPI) during the summer months. Commenters argued that HPI can be used to lower NOX emissions but HPI is not a viable option for all nitric acid plants. The EPA conducted further analyses. Hydrogen peroxide injection is only used during the summer months at the Agrium North Bend plant. Assuming that ozone season (May through September) coincides with the summer months, the analyses shows the maximum 30 operating day emission rate for the year as 0.41 lb NOX/ton acid, for the summer months as 0.40 lb NOX/ton acid and for the non-summer months as 0.39 lb NOX/ton acid. See Figure 2. The analysis of the data from the summer months is independent of the data from the non-summer months. Therefore, the first data point on the graph for summer occurs on May 30, the first 30 day period of the analysis.
The data from the Agrium North Bend plant indicated that the emission limit of 0.50 lb NOX/ton acid is achievable by a modified source that is using the best system of emission reduction. 



Figure 1. Agrium North Bend 30 Day Rolling NOX Emissions -- Varying the Number of Startup and Shutdown Events

Figure 2. Agrium North Bend 30 Day Rolling NOX Emissions -- Use of Hydrogen Peroxide Injection

