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Subpart V—Nitric Acid Production

A nitric acid production facility uses one or more trains 

to produce weak nitric acid (30 to 70 percent in strength). A 

nitric acid train produces weak nitric acid through the 

catalytic oxidation of ammonia.

§ 98.220 Definition of source category.

You must report GHG emissions under this subpart if your 

facility contains a nitric acid train and the facility meets the 

requirements of either §98.2(a)(1) or (a)(2).

§ 98.221 Reporting threshold.

(a) You must report N

§ 98.222 GHGs to report.

2

(b) You must report under subpart C of this part (General 

Stationary Fuel Combustion Sources) the emissions of CO

O process emissions from each nitric 

acid production train as required by this subpart.

2, CH4, 

and N2O from each stationary combustion unit by following the 

requirements of subpart C.

(a) You must determine annual N

§ 98.223 Calculating GHG emissions.

2

(1) Use a site-specific emission factor and production data 

according to paragraphs (b) through (i) of this section.

O process emissions from 

each nitric acid train according to paragraphs (a)(1) or (a)(2) 

of this section.
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(2) Request Administrator approval for an alternative 

method of determining N2

(i) You must submit the request within 45 days following 

promulgation of this subpart or within the first 30 days of each 

subsequent reporting year.

O emissions according to paragraphs 

(a)(2)(i) and (a)(2)(ii) of this section.

(ii) If the Administrator does not approve your requested 

alternative method within 150 days of the end of the reporting 

year, you must determine the N2

(b) You must conduct an annual performance test for each 

nitric acid train according to paragraphs (b)(1) through (b)(3) 

of this section.

O emissions for the current 

reporting period using the procedures specified in paragraph 

(a)(1) of this section.

(1) You must conduct the performance test at the absorber 

tail gas vent, referred to as the test point, for each nitric 

acid train according to §98.224(b) through (f). If multiple 

nitric acid production unitstrains exhaust to a common abatement 

technology and/or emission point, you must sample each process 

in the ducts before the emissions are combined, sample each 

process when only one process is operating, or sample the 

combined emissions when multiple processes are operating and 

base the site-specific emission factor on the combined 
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production rate of the multiple nitric acid production 

unitstrains.

(2) You must conduct the performance test under normal 

process operating conditions.

(3) You must measure the production rate during the 

performance test and calculate the production rate for the test 

period in metric tons (100 percent acid basis) per hour.

(c) Using the results of the performance test in paragraph 

(b) of this section, you must calculate an average site-specific 

emission factor for each nitric acid train “t” according to 

Equation V–1 of this section:

Where:

EFN2Ot = Average site-specific N2O emissions factor for 

nitric acid train “t” (lb N2

C

O/ton nitric acid 

produced, 100 percent acid basis).

N2O = N2O concentration for each test run during the 

performance test (ppm N2

1.14 × 10

O).

−7 = Conversion factor (lb/dscf-ppm N2

Q = Volumetric flow rate of effluent gas for each 

test run during the performance test 

(dscf/hr).

O).

P = Production rate for each test run during the 

performance test (tons nitric acid produced 

per hour, 100 percent acid basis).

n = Number of test runs.
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(d) If nitric acid train “t” exhausts to any N2O abatement 

technology “N” after the test point,”, you must determine the 

destruction efficiency for each N2

(1) Use the manufacturer's specified destruction 

efficiency.

O abatement technology “N” 

according to paragraphs (d)(1), (d)(2), or (d)(3) of this 

section.

(2) Estimate the destruction efficiency through process 

knowledge. Examples of information that could constitute process 

knowledge include calculations based on material balances, 

process stoichiometry, or previous test results provided the 

results are still relevant to the current vent stream 

conditions. You must document how process knowledge (if 

applicable) was used to determine the destruction efficiency.

(3) Calculate the destruction efficiency by conducting an 

additional performance test on the emissions stream following 

the N2

(e) If nitric acid train “t” exhausts to any N

O abatement technology.

2O abatement 

technology “N” after the test point,”, you must determine the 

annual amount of nitric acid produced on nitric acid train “t” 

while N2O abatement technology “N” is operating according to 

§98.224(f). Then you must calculate the abatement utilization 

factor for each N2O abatement technology “N” for each nitric acid 

train “t” according to Equation V–2 of this section.
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Where:

AFt,N = Abatement utilization factor of N2

P

O abatement 

technology “N” at nitric acid train “t” 

(fraction of annual production that abatement 

technology is operating).

t

P

= Total annual nitric acid production from 

nitric acid train “t” (ton acid produced, 100 

percent acid basis).

a,t,N = Annual nitric acid production from nitric acid 

train “t” during which N2

(f) [Reserved]

O abatement technology 

“N” was operational (ton acid produced, 100 

percent acid basis).

(g) You must calculate N2

(1) If nitric acid train “t” exhausts to one N

O emissions for each nitric acid 

train “t” according to paragraph (g)(1), (g)(2), (g)(3), or 

(g)(4) of this section.

2O abatement 

technology “N” after the test point, you must use the emissions 

factor (determined in Equation V–1 of this section), the 

destruction efficiency (determined in paragraph (d) of this 

section), the annual nitric acid production (determined in 

paragraph (i) of this section), and the abatement utilization 

factor (determined in paragraph (e) of this section) according 

to Equation V–3a of this section:

Where:
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EN2Ot = Annual N2

EF

O mass emissions from nitric acid 

production unittrain “t” according to this 

Equation V–3a (metric tons).

N2Ot = Average site-specific N2O emissions factor for 

nitric acid train ”t” (lb N2

P

O/ton acid 

produced, 100 percent acid basis).

t

DF = Destruction efficiency of N

= Annual nitric acid production from thenitric 

acid train “t” (ton acid produced, 100 percent 

acid basis).

2O abatement 

technology N that is used on nitric acid train 

“t” (percentdecimal fraction of N2

AF = Abatement utilization factor of N

O removed 

from vent stream).

2

2205 = Conversion factor (lb/metric ton).

O abatement 

technology “N” for nitric acid train “t” 

(percentdecimal fraction of time that 

theannual production during which abatement 

technology is operating).

(2) If multiple N2O abatement technologies are located in 

series after your test point, you must use the emissions factor 

(determined in Equation V–1 of this section), the destruction 

efficiency (determined in paragraph (d) of this section), the 

annual nitric acid production (determined in paragraph (fi) of 

this section), and the abatement utilization factor (determined 

in paragraph (e) of this section), according to Equation V–3b of 

this section:

Where:
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EN2Ot = Annual N2

EF

O mass emissions from nitric acid 

production unittrain “t” according to this 

Equation V–3b (metric tons).

N2O,t = N2O emissions factor for unitnitric acid train

“t” (lb N2

P

O/ton nitric acid produced).

t

DF

= Annual nitric acid produced from unitnitric 

acid train “t” (ton acid produced, 100 percent 

acid basis).

1 = Destruction efficiency of N2O abatement 

technology 1 (percentdecimal fraction of N2

AF

O 

removed from vent stream).

1 = Abatement utilization factor of N2

DF

O abatement 

technology 1 (percentdecimal fraction of time 

that abatement technology 1 is operating).

2 = Destruction efficiency of N2O abatement 

technology 2 (percentdecimal fraction of N2

AF

O 

removed from vent stream).

2 = Abatement utilization factor of N2

DF

O abatement 

technology 2 (percentdecimal fraction of time 

that abatement technology 2 is operating).

N = Destruction efficiency of N2O abatement 

technology N (percentdecimal fraction of N2

AF

O 

removed from vent stream).

N = Abatement utilization factor of N2

2205 = Conversion factor (lb/metric ton).

O abatement 

technology N (percentdecimal fraction of time 

that abatement technology N is operating).

N = Number of different N2

(3) If multiple N

O abatement technologies.

2O abatement technologies are located in 

parallel after your test point, you must use the emissions 

factor (determined in Equation V–1 of this section), the 

destruction efficiency (determined in paragraph (d) of this 

section), the annual nitric acid production (determined in 

paragraph (fi) of this section), and the abatement utilization 
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factor (determined in paragraph (e) of this section), according 

to Equation V–3c of this section:

Where:

EN2Ot = Annual N2

EF

O mass emissions from nitric acid 

production unittrain “t” according to this 

Equation V–3c (metric tons).

N2O,t = N2O emissions factor for unitnitric acid train

“t” (lb N2

P

O/ton nitric acid produced).

t

DF

= Annual nitric acid produced from unitnitric 

acid train “t” (ton acid produced, 100 percent 

acid basis).

N = Destruction efficiency of N2O abatement 

technology “N” (percentdecimal fraction of N2

AF

O 

removed from vent stream).

N = Abatement utilization factor of N2

FC

O abatement 

technology “N” (percentdecimal fraction of 

time that abatement technology “N” is 

operating).

N = Fraction control factor of N2

2205 = Conversion factor (lb/metric ton).

O abatement 

technology “N” (percentdecimal fraction of 

total emissions from unitnitric acid train “t” 

that are sent to abatement technology “N”).

N = Number of different N2

(4) If nitric acid train “t” does not exhaust to any N

O abatement technologies 

with a fraction control factor.

2O 

abatement technology after the test point, you must use the 

emissions factor (determined in Equation V–1 of this section), 

and the annual nitric acid production (determined in paragraph 

(i) of this section) according to Equation V–3b of this section:
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Where:

EN2Ot = Annual N2

EF

O mass emissions from nitric acid 

production unittrain “t” according to this 

Equation V–3d (metric tons).

N2Ot = Average site-specific N2O emissions factor for 

nitric acid train ”t” (lb N2

P

O/ton acid 

produced, 100 percent acid basis).

t =

2205 = Conversion factor (lb/metric ton).

Annual nitric acid production from nitric acid 

train “t” (ton acid produced, 100 percent acid 

basis).

(h) You must determine the annual nitric acid production 

emissions combined from all nitric acid trains at your facility 

using Equation V–4 of this section:

Where:

N2O = Annual process N2

E

O emissions from nitric acid 

production facility (metric tons).

N2Ot = N2

m = Number of nitric acid trains.

O mass emissions per year for nitric acid 

train “t” (metric tons).

(i) You must determine the total annual amount of nitric 

acid produced on nitric acid train “t” for each nitric acid 

train “t” (tons acid produced, 100 percent acid basis), 

according to §98.224(f).

§ 98.224 Monitoring and QA/QC requirements.
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(a) You must conduct a new performance test according to a 

test plan as specified in paragraphs (a)(1) through (3) of this 

section.

(1) Conduct the performance test annually. The test should 

be conducted at a point during the campaign which is 

representative of the average emissions rate from the nitric 

acid campaigns. Facilities must document the methods used to 

determine the representative point of the campaign when the 

performance test is conducted.

(2) Conduct the performance test when your nitric acid 

production process is changed, specifically when abatement 

equipment is installed.

(3) If you requested Administrator approval for an 

alternative method of determining N2

(b) You must measure the N

O emissions under 

§98.223(a)(2), you must conduct the performance test if your 

request has not been approved by the Administrator within 150 

days of the end of the reporting year in which it was submitted.

2

(1) EPA Method 320 at 40 CFR part 63, appendix A, 

Measurement of Vapor Phase Organic and Inorganic Emissions by 

Extractive Fourier Transform Infrared (FTIR) Spectroscopy.

O concentration during the 

performance test using one of the methods in paragraphs (b)(1) 

through (b)(3) of this section.
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(2) ASTM D6348–03 Standard Test Method for Determination of 

Gaseous Compounds by Extractive Direct Interface Fourier 

Transform Infrared (FTIR) Spectroscopy (incorporated by 

reference in §98.7).

(3) An equivalent method, with Administrator approval.

(c) You must determine the production rate(s) (100 percent

acid basis) from each nitric acid train during the performance 

test according to paragraphs (c)(1) or (c)(2) of this section.

(1) Direct measurement of production and concentration 

(such as using flow meters, weigh scales, for production and 

concentration measurements).

(2) Existing plant procedures used for accounting purposes 

(i.e. dedicated tank-level and acid concentration measurements).

(d) You must determine the volumetric flow rate during the 

performance test in conjunction with the applicable EPA methods 

in 40 CFR part 60, appendices A–1 through A–4. Conduct three 

emissions test runs of 1 hour each. All QA/QC procedures 

specified in the reference test methods and any associated 

performance specifications apply. For each test, the facility 

must prepare an emission factor determination report that must 

include the items in paragraphs (d)(1) through (d)(3) of this 

section.

(1) Analysis of samples, determination of emissions, and 

raw data.
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(2) All information and data used to derive the emissions 

factor(s).

(3) The production rate during each test and how it was 

determined.

(e) You must determine the total monthly amount of nitric 

acid produced. You must also determine the monthly amount of 

nitric acid produced while N2

(f) You must determine the annual amount of nitric acid 

produced. You must also determine the annual amount of nitric 

acid produced while N

O abatement technology (located 

after the test point) is operating from each nitric acid train. 

These monthly amounts are determined according to the methods in 

paragraphs (c)(1) or (2) of this section.

2O abatement technology (located after the 

test point) is operating for each nitric acid train. These 

annual amounts are determined by summing the respective monthly 

nitric acid quantities determined in paragraph (e) of this 

section.

A complete record of all measured parameters used in the 

GHG emissions calculations is required. Therefore, whenever a 

quality-assured value of a required parameter is unavailable, a 

substitute data value for the missing parameter shall be used in 

the calculations as specified in paragraphs (a) and (b) of this 

section.

§ 98.225 Procedures for estimating missing data.
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(a) For each missing value of nitric acid production, the 

substitute data shall be the best available estimate based on 

all available process data or data used for accounting purposes 

(such as sales records).

(b) For missing values related to the performance test, 

including emission factors, production rate, and N2O 

concentration, you must conduct a new performance test according 

to the procedures in §98.224 (a) through (d).

In addition to the information required by §98.3(c), each 

annual report must contain the information specified in 

paragraphs (a) through (p) of this section.

§ 98.226 Data reporting requirements.

(a) TrainNitric Acid train identification number.

(b) Annual process N2

(c) [Reserved]

O emissions from each nitric acid train 

(metric tons).

(d) Annual nitric acid production from each nitric acid 

train during which N2

(e) Annual nitric acid production from the nitric acid 

facility (tons, 100 percent acid basis).

O abatement technology is operating (ton 

acid produced, 100 percent acid basis).

(f) Number of nitric acid trains.

(g) Number of different N2O abatement technologies per 

nitric acid train “t”.
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(h) Abatement technologies used (if applicable).

(i) Abatement technology destruction efficiency for each 

abatement technology (percent destruction).

(j) Abatement utilization factor for each abatement 

technology (fraction of annual production that abatement 

technology is operating).

(k) Type of nitric acid process used for each nitric acid 

train (low, medium, high, or dual pressure).

(l) Number of times in the reporting year that missing data 

procedures were followed to measure nitric acid production 

(months).

(m) If you conducted a performance test and calculated a 

site-specific emissions factor according to §98.223(a)(1), each 

annual report must also contain the information specified in 

paragraphs (m)(1) through (7) of this section.

(1) Emission factor calculated for each nitric acid train 

(lb N2

(2) Test method used for performance test.

O/ton nitric acid, 100 percent acid basis).

(3) Production rate per test run during performance test 

(tons nitric acid produced/hr, 100 percent acid basis).

(4) N2O concentration per test run during performance test 

(ppm N2

(5) Volumetric flow rate per test run during performance 

test (dscf/hr).

O).
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(6) Number of test runs during performance test.

(7) Number of times in the reporting year that a 

performance test had to be repeated (number).

(n) If you requested Administrator approval for an 

alternative method of determining N2

(1) Name of alternative method.

O emissions under 

§98.223(a)(2), each annual report must also contain the 

information specified in paragraphs (n)(1) through (4) of this 

section. (n)(1) through (n)(4) of this section for each nitric 

acid production facility.

(2) Description of alternative method.

(3) Request date.

(4) Approval date.

(o) [Reserved]

(p) Fraction control factor for each abatement technology 

(percent of total emissions from the production unitnitric acid 

train that are sent to the abatement technology) if equation V–

3c is used.

In addition to the information required by §98.3(g), you 

must retain the records specified in paragraphs (a) through (g) 

of this section for each nitric acid production facility:

§ 98.227 Records that must be retained.

(a) Records of significant changes to process.
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(b) Documentation of how process knowledge was used to 

estimate abatement technology destruction efficiency (if 

applicable).

(c) Performance test reports.

(d) Number of operating hours in the calendar year for each 

nitric acid train (hours).

(e) Annual nitric acid permitted production capacity 

(tons).

(f) Measurements, records, and calculations used to 

determine reported parameters.

(g) Documentation of the procedures used to ensure the 

accuracy of the measurements of all reported parameters, 

including but not limited to, calibration of weighing equipment, 

flow meters, and other measurement devices. The estimated 

accuracy of measurements made with these devices must also be 

recorded, and the technical basis for these estimates must be 

provided.

All terms used in this subpart have the same meaning given 

in the Clean Air Act and subpart A of this part.

§ 98.228 Definitions.