Boiler tune ups are a work practice standard that is required by law in the EPA MATS (Mercury and Air Toxins) rule. All utility boilers in excess of 25 MW are required to conform to the MATS rule. Tune ups are required every 36 calendar months (3 years) for units not equipped with a Neural Network Combustion Optimizer and every 48 calendar months (4 years) for units equipped with a Neural Network Combustion Optimizer (§63.10021 (e)).

ICT’s understanding is that the intent of the MATS rule is to reduce boiler emissions, specifically CO and NOx. The testing performed during performance tune ups is intended to evaluate the equipment whose efficiency and performance is most closely tied to CO and NOx emissions and subsequently adjust operating parameters to optimize performance. ICT has experienced personnel on staff and has all of the equipment necessary to conduct a performance tune up.

Below is a summary of §63.10021 (e), which details performance tune up specifications:

MATS Rule Performance Tune Up (Summarized):

  1. Inspect burner and combustion controls [§63.10021(e)(1)]
    1. Clean or replace components as necessary
      1. Any component that affects optimization of CO and NOx must be installed within 3 months
      2. Other component repairs installed on schedule determined by the operator
    2. First burner inspection may be delayed until the next scheduled outage after the implementation of this subpart (April 15, 2015) provided the requirements of §63.10005 are met [§63.10021(e)]
  2. Inspect the flame pattern and make adjustments to the burner or combustion controls to optimize the flame pattern [§63.10021(e)(2)]
    1. Adjustments should be consistent with manufacturer’s specifications or best engineering practices
  3. Observe the damper operations as a function of mill loadings, pulverizer coal feeder loadings, or other pulverizer performance parameters and make any necessary adjustments [§63.10021(e)(3)]
  4. Evaluate windbox pressures and air proportions, making any necessary adjustments/repairs to dampers, actuators, controls, and sensors [§63.10021(e)(4)]
  5. Inspect the system controlling the air-to-fuel ratio and ensure that it is correctly calibrated and functioning properly [§63.10021(e)(5)]
    1. May involve calibration of O2 probes/sensors, adjusting OFA systems, changing software parameters, and calibrating actuators and dampers to ensure systems are operated as designed
  6. Optimize combustion to minimize generation of CO and NOx [§63.10021(e)(6)]
    1. Optimization should be consistent with manufacturer’s specifications or best combustion engineering practice for the burner type
    2. Optimization includes: burners, OFA controls, concentric firing system improvements, neural network/combustion efficiency software, control systems calibrations, adjusting combustion zone temperature profiles, and add on controls (i.e. SCR and SNCR for NOx)
  7. While at full load or predominantly operated load, measure NOx, CO, and O2 concentrations in the effluent stream before and after the tune up adjustments are made
  8. Must maintain on-site and submit (if requested by the Administrator) an annual report containing the information in 1-7 above including: [§63.10021(e)(8-9)]
    1. Concentrations of NOx, CO, and O2 in the effluent before and after adjustment to EGU combustion systems
    2. Description of any corrective actions taken as a part of the combustion adjustment
    3. Type(s) and amount(s) of fuel used over the 12 calendar months prior to an adjustment if the EGU is capable of using more than one type of fuel during that period
    4. Dates of the initial and subsequent tune ups
      1. Initial tune up report must be submitted as a hard-copy and electronically
      2. Subsequent tune up reports must be submitted electronically

Below is a brief outline of ICT’s approach to MATS Performance Tune Ups:


  1. Burners (nozzles, registers, tilts, etc.)
  2. Air and gas systems (dampers, air heaters, expansion joints, windbox, ductwork, etc.)
  3. Pulverizers
  4. Fans


  1. Functional/operational observations during unit load change
  2. Primary air controls/ramp
  3. O2 curve
  4. Verification of unit airflow indications


  1. Baseline testing
    1. Pulverizer performance (fuel fineness, fuel distribution, air-to-fuel ratios, etc.)
    2. Multi-point test of gas species and temperatures at the furnace and economizer exits
    3. Boiler efficiency
    4. Air heater leakage
  2. Tuning (online adjustments to operating parameters) to optimize CO and NOx emissions
  3. Observations
    1. Burner flame shape
    2. Slagging and fouling
  4. Optimization of SCR/SNCR
  5. Final performance test to document improvement


  1. Components determined to need repair following inspection
  2. Adjustments made during the tuning program
  3. CO, NOx, and O2 emissions before and after the completion of the tuning program