





Date:		May 2012

Subject:	Statistical Evaluation of CEMS Data to Determine the NOX Emission Standard (Updated Memo for Final Standard)
		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 a result of the Section 114 Information Collection Request (ICR), EPA received continuous emission monitoring system (CEMS) data from multiple nitric acid plants. The CEMS data represent NOX emissions from the nitric acid trains during day-to-day operating conditions. A summary of the CEMS data received from the nitric acid trains are shown in Table 1, Table 2, and Table 3.
Only data from the most recent year was considered in the analyses. Some facilities only submitted one year of data so we only considered one year of data from all submissions so as not to bias the analysis toward a plant with more data.
As shown in Table 1, Table 2, and Table 3, we received CEMS data for three nitric acid trains with Selective Catalytic Reduction (SCR), three nitric acid trains with Non-Selective Catalytic Reduction (NSCR), and one nitric acid train with Hydrogen Peroxide Injection (HPI). Agrium (North Bend and Sacramento) supplied 2010 data, El Dorado Nitrogen supplied data from July 2010 through June 2011, Dyno Nobel Deer Island and Agrium Kennewick supplied 2009 data, and PCS Geismar supplied 2009 data from Train 5, Train 4, and Train 3.

The CEMS data from JR Simplot were not in terms of the standard (lb NOX/ton acid) and were not supplied as hourly averages. The data were not directly comparable to the data from the other two nitric acid trains using NSCR so the nitric acid train at JR Simplot is not included in the analyses. 
Train 3 and Train 4 at PCS Geismar were not included in the analyses because the trains only operated during 15% of 2009. The trains did not operate at all during the months of February, March, April, May, June, July, August, and December. Sufficient data to evaluate the long term performance of controls for this analysis were not available as there are only portions of 4 months of data, No CEMS data from other years were supplied for Train 4.
The other years of CEMS data were not used for Train 3 because the nitric acid plant is not using a best performing SCR. According to a telephone conversation between EPA's Bill Neuffer and Jeremy Richard of PCS Geismar, the SCR is located after the gas expander and is thus an atmospheric SCR. According to Mr. Richard, this prevents optimal mixing of gas and ammonia, leading to higher NOX emissions. He felt that the unit could be improved to meet a lower emissions limit on a consistent basis. The CEMS data include periods of startup and shutdown but exclude non-operating periods. Non-operating periods were indicated by the plants as "Down" or "Plant Down" for the lb/ton acid value (Agrium and El Dorado) or the flow rate of the ammonia feed was zero pounds per hour (PCS Geismar).
Just before the NSPS was proposed, the EPA received CEMS data from Dyno Nobel Deer Island. There was insufficient time to include these data in the analyses prior to proposal. During the comment period, commenters noted a few mistakes in the analyses for the facilities that the EPA did evaluate prior to proposal. Also, the EPA has slightly modified the NOX emissions calculation equation for the 30-day rolling emission rate. The new equation assumes that each hour that the unit was operating during the 30 day period is weighted the same. The equation used at proposal equally weighted each day that the unit was operating regardless of how many hours during each day the unit operated. On partial operating days with startup or shutdown events, the methodology could have caused the emissions during those events to be weighted too heavily in the 30 day rolling emission rate.
As an update to the earlier memo (Docket ID EPA-HQ-OAR-2010-0750-0082), this memo shows the 30 day rolling emission rates used at proposal, shows how the 30 day rolling emission rates change after modifying the calculation and includes the updated calculation methodology. Also, the updated memo includes the analyses of data from Dyno Nobel Deer Island and Agrium Kennewick that were not included at proposal.
By selecting an emission limit based on the highest average of emissions data from unit with BSER (which is SCR), we ensure that this limit reflects BSER but is also achievable during all periods by facilities that have BSER equivalent controls. As shown by Table 4, all six units are meeting the current Subpart G NOX emission standard of 3.0 lb NOX/ton acid. All SCR units are meeting the proposed Subpart Ga NOX emission standard of 0.50 lb NOX/ton acid, and one NSCR unit is meeting the proposed Subpart Ga NOX emission standard of 0.50 lb NOX/ton acid. The HPI unit is not meeting the proposed Subpart Ga NOX emission standard of 0.50 lb NOX/ton acid. 
In conjunction with the memo entitled Agrium North Bend Analyses, finalizing a NOX emission standard of 0.50 lb/ton NOX/ton acid is recommended.


Table 1. NOX CEMS Data from SCR-controlled Nitric Acid Units 

                                    Company
                              Agrium -- North Bend
                Coffeyville Resources Nitrogen Fertilizers, LLC
                              El Dorado Nitrogen
                             PCS Nitrogen-Geismar
                                    Train 3
                             PCS Nitrogen-Geismar
                                    Train 5
Basis
                                Hourly averages
                  Requested from plant but have not received
                                Hourly averages
                              15-minute readings
                              15-minute readings
Volume of data
                                    1 year
                  Requested from plant but have not received
                                    1 year
                                    3 years
                      (was only operational 15% of 2009)
                                    3 years

Table 2. NOX CEMS Data from NSCR-controlled Nitric Acid Units 

                                    Company
                               Agrium-Sacramento
                      Dyno Nobel-Cheyenne (Acid Plant 1)
                      Dyno Nobel-Cheyenne (Acid Plant 2)
                            Dyno Nobel-Deer Island
                                  JR Simplot
                             PCS Nitrogen-Geismar
                                   (Train 4)
                                     Basis
                                  Hourly ppm
                                      NA
                                      NA
                               1 minute readings
                               (lb NOX/ton acid)
                                Monthly avg ppm
                     15-minute readings (lb NOX/ton acid)
                                Volume of data
                 1 year (only operating about 50% of the year)
                                     None
                                     None
                                    1 year
                                    3 years
                    1 year (only operating 15% of the year)
      
Table 3. NOX CEMS Data from HPI-controlled Nitric Acid Units 

                                    Company
                              Agrium -- Kennewick
Basis
                      2 minute readings (lb NOX/ton acid)
Volume of data
                                    3 years
      
      

Table 4. CEMS Data -- Highest Average
                                     Train
                    30 day rolling emission rate--proposal 
                               (lb NOX/ton acid)
                    30 operating day rolling emission rate
                               (lb NOX/ton acid)
PCS Geismar-Train 5 (SCR)
                                                                           0.39
                                                                           0.35
Agrium North Bend (SCR)
                                                                           0.50
                                                                           0.41
El Dorado Nitrogen (SCR)
                                                                           0.37
                                                                           0.37
Dyno Nobel Deer Island (NSCR)
                                                                         ------
                                                                           0.21
Agrium Sacramento (NSCR)
                                                                           1.81
                                                                           0.96
Agrium Kennewick (HPI)
                                                                         ------
                                                                           0.72

      
      
      
  
Figure 1. PCS Geismar Train 5 NOX Emission Data
Figure 2. Agrium North Bend NOX Emission Data   
Figure 3. El Dorado Nitrogen NOX Emission Data 
Figure 4. Dyno Nobel Deer Island NOX CEMS Data 
Figure 5. Agrium Sacramento NOX CEMS Data 
Figure 6. Agrium Kennewick NOX CEMS Data 

