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**Subpart E**

**—**

**Adipic Acid**  **Production §98.50**  **Definition of source category.**  The adipic acid production source category consists of all adipic acid production facilities that use oxidation to produce adipic acid. **§98.51 Reporting threshold.**  You must report GHG emissions under this subpart if your facility contains an adipic acid production process and the facility meets the requirements of either §98.2(a)(1) or (2). **§98.52 GHGs to report.**  (a) You must report N 2 O process emissions at the facility level. (b) You must report under subpart C of this part (General St ationary Fuel Combustion Sources) the emissions of CO 2 , CH 4 , and N 2 O from each stationary combustion unit following the requirements of subpart C. **§98.53 Calculating GHG emissions.**  (a) You must determine annual N 2 O emissions from adipic acid production acc ording to paragraphs (a)(1) or (2) of this section. (1) Use a site
- specific emission factor and production data according to paragraphs (b) through (i) of this section. (2) Request Administrator approval for an alternative method of determining N 2 O emissio ns according to paragraphs (a)(2)(i) through (i v ) of this section. (i ) If you received Administrator approval for an alternative method of determining N2 O emissions in the previous reporting year and your methodology is unchanged , your alternative method is automatically

approved for the next reporting year.Page 2 of 13

(ii) You must notify

the EPA of your use of a previously approved alternative method in yo ur annual report. (i i i ) Otherwise, you must submit the request within 45 day s following promulgation of this subpart or within the first 30 days of each subsequent reporting year. (i v ) If the Administrator does not approve your requested alternative method within 150 day s of the end of the reporting year, you must determine the N 2 O emissions for the current reporting period using the procedures specified in paragraph ( a ) (1) of this section. (b) You must conduct an annual performance test according to paragraphs (b)(1) through (3) of this section. (1) You must conduct the test on the vent stream from the nitric acid oxidation step of the process, referred to as the test point, according to the methods specified in §98.54(b) through (f). If multiple adipic acid production units exhaust to a common abatement technology and/or emission point, yo u 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 c ombined production rate of the multiple adipic acid production units. (2) You must conduct the performance test under normal process operating conditions. (3) You must measure the adipic acid production rate during the test and calculate the production rat e for the test period in tons per hour. (c) Using the results of the performance test in paragraph (b) of this section, you must calculate an emission factor for each adipic acid unit according to Equation E
- 1 of this section:Page 3 of 13

where: EF N2O,z = Average fa cility
- specific N 2 O emission factor for each adipic acid production unit “z” (lb N 2 O/ton adipic acid produced). C N2O = N 2 O concentration per test run during the performance test (ppm N 2 O). 1.14 × 10 −7 = Conversion factor (lb/dscf
- ppm N 2 O). Q = Volumetric flow rate of effluent gas per test run during the performance test (dscf/hr). P = Production rate per test run during the performance test (tons adipic acid produced/hr). n = Number of test runs. (d) If the adipic acid production unit exhausts to any N 2 O a batement technology

“N”, you must determine the destruction efficiency according to paragraphs (d)(1), (d)(2), or (d)(3) of this section. (1) Use the manufacturer's specified destruction efficiency
. (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 was used to determine the destruction efficiency
. (3) Calculate the destruction efficiency by conducting an additional performance test on the vent stream following the N 2 O abatement technology
. (e) If the adipic acid pro duction unit exhausts to any N 2 O abatement technology “N”, you must determine the annual amount of adipic acid produced while N2 O abatement technology “N”Page 4 of 13

is operating according to §98.54(f). Then you must calculate the abatement factor for N 2 O abatement t echnology

“N” according to Equation E
- 2 of this section.

(f) You must determine the annual amount of adipic acid produced according to §98.54(f). (g) You must calculate N 2 O emissions according to paragraph (g)(1), (2), (3), or (4) of this section for ea ch adipic acid production unit. (1) If one N 2 O abatement technology “N” is located after your test point, you must use the emissions factor (determined in Equation E
- 1 of this section), the destruction efficiency (determined in paragraph (d) of this sectio n), the annual adipic acid production (determined in paragraph (f) of this section), and the abatement utilization factor (determined in paragraph (e) of this section), according to Equation E
- 3a of this section:

where: E a,z = Annual N 2 O mass emissions f rom adipic acid production unit “z” according to this Equation E
- 3a (metric tons). EF N2Oz = N 2 O emissions factor for unit “z” (lb N 2 O/ton adipic acid produced). P z = Annual adipic acid produced from unit “z” (tons). DF = Destruction efficiency of N 2 O abate ment technology “N” (decimal fraction of N 2 O removed from vent stream). AF = Abatement utilization factor of N 2 O abatement technology “N” (decimal fraction of time that the abatement technology is operating). 2205 = Conversion factor (lb/metric ton).Page 5 of 13

(2) I f multiple N 2 O abatement technologies are located in series after your test point, you must use the emissions factor (determined in Equation E
- 1 of this section), the destruction efficiency (determined in paragraph (d) of this section), the annual adipic a cid production (determined in paragraph (f) of this section), and the abatement utilization factor (determined in paragraph (e) of this section), according to Equation E
- 3b of this section:

where: E b,z = Annual N 2 O mass emissions from adipic acid production unit “z” according to this Equation E
- 3b (metric tons). EF N2O,z = N 2 O emissions factor for unit “z” (lb N 2 O/ton adipic acid produced). P z = Annual adipic acid produced from unit “z” (tons). DF 1 = Destruction efficiency of N 2 O abatement technology 1 (decimal fraction of N 2 O removed from vent stream). AF 1 = Abatement utilization factor of N 2 O abatement technology 1 (decimal fraction of time that abatement technology 1 is operating). DF 2 = Destruction efficiency of N 2 O abatement technology 2 (decimal fraction of N 2 O removed from vent stream). AF 2 = Abatement utilization factor of N 2 O abatement technology 2 (decimal fraction of time that abatement technology 2 is operating). DF N = Destruction efficiency of N 2 O abatement technology “N” (decimal fraction of N 2 O removed from vent stream). AF N = Abatement utilization factor of N 2 O abatement technology “N” (decimal fraction of time that abatement technology N is operating).Page 6 of 13

2205 = Conversion factor (lb/metric ton). N = Number of different N 2 O abatement technolo gies. (3) If multiple N 2 O abatement technologies are located in parallel after your test point, yo u must use the emissions factor (determined in Equation E
- 1 of this section), the destruction efficiency (determined in paragraph (d) of this section), the annual adipic acid production (determined in paragraph (f) of this section), and the abatement utilization factor (determined in paragraph (e) of this section), according to Equation E
- 3c of this section:

where: E c,z = Annual N 2 O mass emissions from adipic acid production unit “z” according to this Equation E
- 3c (metric tons). EF N2O,z = N 2 O emissions factor for unit “z” (lb N 2 O/ton adipic acid produced). P z = Annual adipic acid produced from unit “z” (tons). DF N = Destruction efficiency of N 2 O abatement tec hnology “N” (decimal fraction of N 2 O removed from vent stream). AF N = Abatement utilization factor of N 2 O abatement technology “N” (decimal fraction of time that the abatement technology is operating). FC N = Fraction control factor of N 2 O abatement technol ogy “N” (decimal fraction of total emissions from unit “z” that are sent to abatement technology “N”). 2205 = Conversion factor (lb/metric ton). N = Number of different N 2 O abatement technologies with a fraction control factor. (4) If no N 2 O abatement technologies are located after your test point, you must use the emissions factor (determined using Equation E
- 1 of this section) and the annual adipic acidPage 7 of 13

production (determined in paragraph (f) of this section) according to Equation E
- 3d of this section for each adipic acid production unit.

where: E d,z = Annual N 2 O mass emissions from adipic acid production for unit “z” according to this Equation E
- 3d (metric tons). EF N2O = N 2 O emissions factor for unit “z” (lb N 2 O/ton adipic acid produced). P Z = Annual adipic acid produced from unit “z” (tons). 2205 = Conversion factor (lb/metric ton). (h) You must determine the emissions for the facility by summing the unit level emissions according to Equation E
- 4 of this section.

where: E a,z = Annual N 2 O mass emissions from adipic acid production unit “z” according to Equation E
- 3a of this section (metric tons). E b,z = Annual N 2 O mass emissions from adipic acid production unit “z” according to Equation E
- 3b of this section (metric tons). E c,z = Annual N 2 O mass emissions from adipic acid production unit “z” according to Equation E
- 3c of this section (metric tons). E d,z = Annual N 2 O mass emissions from adipic acid production unit “z” according to Equation E
- 3d of this section (metric tons). M = Total number o f adipic acid production units.Page 8 of 13

(i) You must determine the amount of process N 2 O emissions that is sold or transferred off site (if applicable). You can determine the amount using existing process flow meters and N 2 O analyzers. [75 FR 66458, Oct. 28, 2010, as amended at 78 FR 71952, Nov. 29, 2013] **§98.54 Monitoring and QA/QC requirements.**  (a) You must conduct a new performance test and calculate a new emissions factor for each adipic acid production unit according to the frequency specified in paragraphs (a)(1) through (3) of this section. (1) Conduct the performance test annuall y. The test must be conducted at a point during production that is representative of the average emissions rate from your process. You must document the methods used to determine the representative point. (2) Conduct the performance test when your adipic acid production process is changed either b y altering the ratio of cyclohexanone to cyclohexanol or by installing abatement equipment. (3) If you requested Administrator approval fo r an alternative method of determining N 2 O emissions under §98.53(a)(2), you must conduct the performance test if your request has not been approved b y the Administrator within 150 days of the end of the reporting year in which it was submitted. (b) You mu st measure the N 2 O concentration during the performance test using one of the methods in paragraphs (b)(1) through (b)(3) of this section. (1) EPA Method 320, Measurement of Vapor Phase Organic and Inorganic Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscop y in 40 CFR part 63, Appendix A;Page 9 of 13

(2) ASTM D6348
- 03 Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared (FTIR) Spectroscopy (incorporated by reference, see §98.7); or (3) An equivalent method, with Administrator approval. (c) You must determine the adipic acid production rate during the performance test according to paragraph (c)(1) or (c)(2) of this section. (1) Direct measurement (such as using flow meters or weigh scale s). (2) Existing plant procedures used for accounting purposes. (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 emission s 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 emissions factor determination report that must include the items in p aragraphs (d)(1) through (d)(3) of this section: (1) Anal ys is of samples, determination of emissions, and raw data. (2) All information and data used to derive the emissions factor. (3) The production rate(s) during the performance test and how each produc tion rate was determined. (e) You must determine the monthly amount of adipic acid produced. You must also determine the monthly

amount of adipic acid produced during which N 2 O abatement technology is operating. These monthly amounts are determined according to the methods in paragraphs (c)(1) or (c)(2) of this section.Page 10 of 13

(f) You must determine the annual amount of adipic acid produced. You must also determine the annual amount of adipic acid produced during which N 2 O abatement technology is operating. These are determined by summing the respective monthly adipic acid production quantities determined in paragraph (e) of this section. [74 FR 56374, Oct. 30, 2009, as amended at 75 FR 66460, Oct. 28, 2010; 78 FR 71953, Nov. 29, 2013] **§98.55 Procedures for estimat** **ing missing data.** 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 b e used in the calculations as specified in paragraphs (a) and (b) of this section. (a) For each missing value of monthly adipic 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 N 2 O concentration, you must conduct a new performance test according to the procedures in §98.54 (a) through (d). **§ 98. 56**  **Data reporting requirements.** In addition to the information required b y § 98. 3(c), each annual report must contain the information specified in paragraphs (a) through (n ) of this section at the facility level. (a) Annual process N 2 O emissions from adipic acid production (metric tons). (b) Reserved
. (c) Reserved
.Page 11 of 13

(d) Annual process N 2 O emissions from adipic acid production facility that is sold or transferred off site (metric tons). (e) Number of abatement technologies (if applicable). (f) T ypes of abatement technologies used and date of installation for each (if applicable). (g) Abatement technology destruction efficiency

for each abatement technology (percent destruction). (h) Abatement utilization factor for each abatement technology (fraction of annual production that abatement technology is operating). (i) Number of times in the reporting ye ar that missing data procedures were followed to measure adipic acid production (months). (j) If you conducted a performance test and calculated a site
- specific emissions factor according to § 98. 53(a)(1), each annual report must also contain the information specified in paragraphs (j)(1) through (7) of this section for each adipic acid production unit. (1) Reserved
. (2) Test method used for perfor mance test. (3) Reserved
. (4) N 2 O concentration per test run during performance test (ppm N 2 O). (5) Volumetric flow rate per test run during performance test (dscf/hr). (6) Number of test runs. (7) Number of times in the reporting ye ar that a performance t est had to be repeated (number).Page 12 of 13

(k) If you requested Administrator approval for an alternative method of determining N 2 O emissions under § 98. 53(a)(2), each annual report must also contain the information specified in paragraphs (k)(1) through (4) of this section for each adipic acid production facility. (1) Name of alternative method. (2) Description of alternative method. (3) Request date. (4) Approval date. (l) Fraction control factor for each abatement technology (percent of total emissions from the production unit that are sent to the abatement technology) if equation E
- 3c is used. (m) If onl y c yclohexane is oxidized to produce adipic acid and the quantity is known , report the information specified in paragraph (m)(1) of this section. If materials other than cyclohexane are oxidized to produce adipic acid, report the information specified in paragraph (m)(2) of this section. (1) Annual quantity of c yclohexane (tons) used to produce adipic acid. (2) Annual quantity of c yclohexanone and cyclohexanol mixture (tons) used to produce adipic acid. (n) Annual percent N 2 O emission reduction for all production units combined. **§ 98. 57**  **Records that must be retained.** In addition to the information required b y § 98. 3(g), you must retain the records specified in p aragraphs (a) through ( i ) of this section at the facility level: (a) Annual adipic acid production capacity (tons). (b) Records of significant changes to process. (c) Number of facility

and unit operating hours in calendar year.Page 13 of 13

(d) Documentation of how ac counting procedures were used to estimate production rate. (e) Documentation of how process knowledge was used to estimate abatement technology

destruction efficiency
. (f) Performance test reports. (g) Measurements, records and calculations used to determine reported parameters. (h) 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 estimat ed accuracy of measurements made with these devices must also be recorded, and the technical basis for these estimates must be provided. (i) Verification software records . You must keep a record of the file generated by the verification software specified in § 98 .5(b) for the applicable data specified in paragraphs (i)(1) through ( 3 ) of this section. Retention of this file satisfies the recordkeeping requirement for the data in paragraphs (i)(1) through ( 3 ) of this section. (1) Annual adipic acid production from each adipic acid production unit (tons)(Equations E
- 2, E
- 3a, E
- 3b, E
- 3c, and E
- 3d of § 98.53 ). ( 2 ) Production rate per test run during the performance test for each production unit test
run (tons adipic acid produced/hr) (Equation E
- 1 of § 98.53 ). ( 3 ) Annual adipic acid production per N 2 O abatement technology during which N 2 O abatement technology

was used (tons adipic acid produced) (Equation E
- 2). **§98.58 Definitions.**  All terms used in this subpart have the same meaning given in the Clean Air Act and subpart A of this part.