Ind. Admin. Code tit. 326, r. 10-7-4
Authority: IC 13-14-8-1; IC 13-14-9; IC 13-17-3-4
Affected: IC 13-17-3
Sec. 4. (a) Owners or operators of small boilers shall:
(1) annually perform a tune-up; and
(2) maintain a logbook in a format approved by the department that includes the following information:
(A) The date of the last tune-up.
(B) The name, title, and affiliation of the person who performed the tune-up and made any adjustments.
(C) Any other information which the department may require as a condition of approval of any permit for the boiler.
(b) Owners or operators of mid-size, large, and very large boilers shall not emit NOx in excess of the following:
(1) 0.08 lb/mmBtu for gas-only fueled boilers.
(2) 0.10 lb/mmBtu for distillate oil fueled boilers.
(3) 0.20 lb/mmBtu for residual oil fueled boilers.
(c) Unless a more stringent limit is included in a permit, owners or operators of stationary combustion turbines for mechanical drive and electrical generation shall not emit NOx in excess of the following:
Table 1 – NOx Emissions Limitations for Stationary Combustion Turbines
| Combustion turbine type | Combustion turbine heat input at peak load (HHV) | NOX emission standard |
|---|---|---|
| Turbine firing natural gas | > 50 and ≤ 850 mmBtu/hr | 25.0 ppm at 15 percent O2 or 150 ng/J of useful output (1.2 lb/MW-hr) |
| > 850 mmBtu/hr | 25.0 ppm at 15 percent O2 or 54 ng/J of useful output (0.43 lb/MW-hr) |
(d) Unless a more stringent limit is included in a permit, owners or operators of stationary internal combustion engines shall not emit NOx in excess of the following:
Table 2 – NOx Emissions Limitations for Stationary RICE
| Ignition System | Maximum Engine Power (kW [hp]) | NOx (g/kW-hr [g/hp-hr]) |
|---|---|---|
| Compression Ignition | 373 < kW ≤ 560 [500 < hp ≤ 751] | 0.40 [0.30] |
| kW > 560 [hp > 751] generator sets | 0.67 [0.50] | |
| kW > 560 [hp > 751] All except generator sets | 3.5 [2.61] | |
| Spark Ignition | 373 < kW [500 < hp] | 2.7 [2.0] |
(e) Unless a more stringent limit is included in a permit, owners or operators of reheat, annealing, and galvanizing furnaces with a maximum heat input capacity of equal or greater than seventy-five (75) mmBtu/hr shall not emit NOx in excess of 0.09 lb/mmBtu.
(Air Pollution Control Division; 326 IAC 10-7-4; filed Oct 27, 2025, 10:54 a.m.: 20251126-IR-326250204FRA)