VENTURA COUNTY AIR POLLUTION CONTROL DISTRICT

Rule 74.15.1 Boilers, Steam Generators, and Process Heaters

(Adopted 5/11/93, Revised 6/13/95)

A. Applicability

The provisions of this rule apply to any boiler, steam generator, or process heater with a rated heat input capacity equal to or greater than 1 million BTU per hour and less than 5 million BTU per hour.

B. Requirements

  1. No person shall allow the discharge into the atmosphere, from any boiler, steam generator, or process heater with an annual heat input rate of equal to or greater than 1.8 x 109 BTU, oxides of nitrogen (NOx) emissions in excess of 30 parts per million volume (ppmv). Carbon monoxide (CO) emissions from units subject to this rule shall not exceed 400 ppmv.

    Units subject to the above provisions shall test for compliance not less than once every 24 months.

  2. Any boiler, steam generator, or process heater with an annual heat input rate of equal to or greater than 0.3 x 109 BTU and less than 1.8 x 109 BTU shall comply with one of the following requirements:
    1. The unit shall be tuned every 6 months or after 750 hours of operation since the previous tune-up, whichever occurs last, but in no case less than once per calendar year. The unit shall be tuned in accordance with the procedure described in Attachment 1 for forced draft-fired equipment or Attachment 2 for natural draft-fired equipment; or
    2. The unit shall comply with the emission and testing requirements of Subsection B.1.

C. Exemptions

The provisions of Subsection B.1 of this rule shall not apply to any unit operated on alternate fuel under the following conditions:

  1. Alternate fuel use is required due to the curtailment of natural gas service to the individual unit by the natural gas supplier. Alternate fuel use in this case shall not exceed the period of natural gas curtailment.

  2. Alternate fuel use is required to maintain the alternate fuel system. Alternate fuel use in this case shall not exceed 50 hours per year.

    The provisions of Subsection B.2 of this rule shall not be required for alternate fuel use.

D. Recordkeeping Requirements

  1. Any person owning and/or operating a boiler, steam generator, or process heater with an annual heat input rate of less than 1.8 x 109 BTU and not complying with the requirements of Subsection B.1 shall install a totalizing fuel meter for each applicable unit and for each fuel. Meters shall be accurate to + one (1) percent, as certified by the manufacturer in writing. Fuel consumption for each unit shall be compiled monthly into a rolling twelve (12) calendar month report.

  2. Any person subject to the provisions of Subsection B.2.a shall submit a report to the Air Pollution Control Officer (APCO) within twelve (12) months after achieving compliance with Subsection B.2.a. Reports shall continue to be submitted every twelve (12) months. This report shall verify that each tune-up has been performed and the results were satisfactory. The report shall contain all information and or documentation that the APCO may determine, in writing, to be necessary.

  3. Any person utilizing alternate fuel, pursuant to the provisions of Subsection C.1 of this rule, shall maintain daily records of each occurrence. Each record shall include the type of fuel, the quantity of fuel, and the duration of the occurrence.

  4. All records required by Subsections D.1 and D.3 shall be maintained for a period of four (4) years and shall be available for inspection by the APCO upon request.

E. Test Methods

  1. Compliance with the emission requirements in Section B shall be determined using ARB Method 100 for Oxides of Nitrogen, Carbon Monoxide, and Stack Gas Oxygen.

  2. Emission tests resulting in compliance determinations for the requirements of Subsection B.1 shall be conducted on units in "As-found" operating condition. However, no emission test for this rule shall be conducted during start-up, shutdown or under breakdown conditions.

  3. The NOx parts per million emission limitation specified in Subsection B.1. is expressed as nitrogen dioxide. The limitations for both NOx and CO are referenced at three (3) percent volume stack gas oxygen on a dry basis averaged over 15 consecutive minutes.

F. Violations

  1. Failure to comply with any provision of this rule shall constitute a violation of this rule.

  2. Any unit subject to the provisions of Subsection B.2 shall comply with the provisions of Subsection B.1 if the unit operates during any rolling twelve (12) month period at a total annual heat input rate greater than the applicable annual heat input rate specified in Subsection B.2.

  3. Any unit previously operating at an annual heat input rate of less than 0.3 x 109 BTU shall comply with the applicable provisions of Subsection B.1 or Subsection B.2 if the unit operates during any rolling twelve (12) month period at a total annual heat input rate greater than 0.3 x 109 BTU.

G. Definitions

  1. "Annual Heat Input": The actual amount of heat released by fuels burned in a unit during a twelve (12) calendar month rolling period, based on the fuel's higher heating value. The annual heat input shall be calculated as the sum of the previous 12 monthly fuel use rates multiplied by the fuel's higher heating value.

  2. "Boiler or Steam Generator": Any external combustion equipment fired with liquid and/or gaseous fuel and used to produce steam or to heat water. Boiler or Steam Generator does not include any unfired waste heat recovery boiler that is used to recover sensible heat from the exhaust of any combustion equipment.

  3. "Process Heater": Any external combustion equipment fired with liquid and/or gaseous fuel and which transfers heat from combustion gases to water or process streams. Process Heater does not include any kiln or oven used for drying, baking, cooking, calcining or vitrifying, any unfired waste heat recovery heater that is used to recover sensible heat from the exhaust of any combustion equipment, or any fuel-fired degreasing or metal finishing equipment.

  4. "Rated Heat Input Capacity": The heat input capacity specified on the nameplate of the combustion unit. If the combustion unit has been altered or modified such that its maximum heat input is different than the heat input capacity specified on the nameplate, the new maximum heat input shall be considered as the rated heat input capacity. This alteration or modification can be through either burner alteration or modification or installation of a fixed orifice. The new maximum heat input must be certified, in writing, by the manufacturer or installer and engineering calculations supporting the new maximum heat input rating must be submitted to the APCO.

  5. "Therm": 100,000 BTU.

  6. "Unit": Any boiler, steam generator, or process heater as defined in Subsections G.2 and G.3 of this rule.

H. Increments of Progress

  1. If total NOx emissions from all sources in this District owned and operated by the same business equal 25 tons or more per year or the business owner/operator has three or fewer units subject to Subsection B.1, complete Authority to Construct applications shall be submitted to the APCO by May 31, 1994, and final compliance shall be demonstrated by May 31, 1995.

  2. If total NOx emissions from all sources in this District owned and operated by the same business are less than 25 tons per year and the business owner/operator has four or more units subject to the requirements of Subsection B.1:
    1. A compliance schedule shall be submitted to the APCO for approval by May 31, 1994.
    2. Final compliance for 25 percent of the units shall be demonstrated by May 31, 1995 and for an additional 25 percent each May 31 thereafter until final compliance for all units is demonstrated by May 31, 1998. Complete Authority to Construct applications shall be submitted to the APCO at least one year prior to the required compliance date.
  3. For units subject to Subsection B.2, final compliance shall be demonstrated by November 30, 1994.







ATTACHMENT (1)

Equipment Tuning Procedure for Forced Draft-fired Equipment(2)

Nothing in this Equipment Tuning Procedure shall be construed to require any act or omission that would result in unsafe conditions or would be in violation of any regulation or requirement established by Factory Mutual, Industrial Risk Insurers, National Fire Prevention Association, the California Department of Industrial Relations (Occupational Safety and Health Division), the Federal Occupational Safety and Health Administration, or other relevant regulations and requirements.

  1. Operate the unit at the firing rate most typical of normal operation. If the unit experiences significant load variations during normal operation, operate it at its average firing rate.

  2. At this firing rate, record stack gas temperature, oxygen concentration, and CO concentration (for gaseous fuels) or smoke-spot number(3) (for liquid fuels), and observe flame conditions after unit operation stabilizes at the firing rate selected. If the excess oxygen in the stack gas is at the lower end of the range of typical minimum values(4) , and if the CO emissions are low and there is not smoke, the unit is probably operating at near optimum efficiency - at this particular firing rate. However, complete the remaining portion of this procedure to determine whether still lower oxygen levels are practical.

  3. Increase combustion air flow to the furnace until stack gas oxygen levels increase by one to two percent over the level measured in Step 2. As in Step 2, record the stack gas temperature, CO concentration (for gaseous fuels) or smoke-spot number (for liquid fuels), and observe flame conditions for these higher oxygen levels after boiler operation stabilizes.

  4. Decrease combustion air flow until the stack gas oxygen concentration is at the level measured in Step 2. From this level gradually reduce the combustion air flow, in small increments. After each increment, record the stack gas temperature, oxygen concentration, CO concentration (for gaseous fuels) and smoke-spot number (for liquid fuels). Also observe the flame and record any changes in its condition.

  5. Continue to reduce combustion air flow stepwise, until one of these limits in reached:
    1. Unacceptable flame conditions - such as flame impingement on furnace walls or burner parts, excessive flame carryover, or flame instability.
    2. Stack gas CO concentrations greater than 400 ppm.
    3. Smoking at the stack.

    4. Equipment-related limitations - such as low windbox/furnace pressure differential, built in air-flow limits, etc.
  6. Develop an 02/CO curve (for gaseous fuels) or 02/smoke curve (for liquid fuels) similar to those shown in Figures 1 and 2 using the excess oxygen and CO or smoke-spot number data obtained at each combustion air flow setting.

  7. From the curves prepared in Step 6, find the stack gas oxygen levels where the CO emissions or smoke-spot number equal the following values:

    Fuel Measurement Value
    Gaseous CO Emissions 400 ppm
    #1 & #2 oils smoke-spot number number 1
    #4 oil smoke-spot number number 2
    #5 oil smoke-spot number number 3
    Other oils smoke-spot number number 4

    The above conditions are referred to as CO or smoke threshold, or as the minimum excess oxygen level.

    Compare this minimum value of excess oxygen to the expected value provided by the combustion unit manufacturer. If the minimum level found is substantially higher than the value provided by the combustion unit manufacturer, burner adjustments can probably be made to improve fuel and air mixing, thereby allowing operation with less air.

  8. Add 0.5 to 2.0 percent to the minimum excess oxygen level found in Step 7 and reset burner controls to operate automatically at this higher stack gas oxygen level. This margin above the minimum oxygen level accounts for fuel variations, variations in atmospheric conditions, load changes, and nonrepeatability or play in automatic controls.

  9. If the load of the combustion unit varies significantly during normal operation, repeat Steps 1-8 for firing rates that represent the upper and lower limits of the range of the load. Because control adjustments at one firing rate may affect conditions at other firing rates, it may not be possible to establish the optimum excess oxygen level at all firing rates. If this is the case, choose the burner control settings that give best performance over the range of firing rates. If one firing rate predominates, settings should optimize conditions at that rate.

  10. Verify that the new settings can accommodate the sudden changes that may occur in daily operation without adverse effects. Do this by increasing and decreasing load rapidly while observing the flame and stack. If any of the conditions in Step 5 result, reset the combustion controls to provide a slightly higher level of excess oxygen at the affect firing rates. Next, verify these new settings in a similar fashion. Then make sure that the final control settings are recorded at steady-state operating conditions for future reference.





ATTACHMENT 2

Equipment Tuning Procedure for Natural Draft-Fired Equipment

Nothing in this Equipment Tuning Procedure shall be construed to require any act or omission that would result in unsafe conditions or would be in violation of any regulation or requirement established by Factory Mutual, Industrial Risk Insurers, National Fire Prevention Association, the California Department of Industrial Relations (Occupational Safety and Health Division). the Federal Occupational Safety and Health Administration, or other relevant regulations and requirements. Steps in the Procedure not applicable to specific units may be omitted.

  1. Preliminary Analysis

    a. Verify that the boiler, steam generator, or process heater (unit) is operating at the lowest pressure or temperature that will satisfy load demand. This pressure or temperature will be used as a basis for comparative combustion analysis before and after tune-up.

    b. Verify that the unit operates for the minimum number of hours and days necessary to perform the work required.

    c. Verify that the size of air supply openings is in compliance with applicable codes and regulations. Air supply openings must be fully open when the burner is firing and air flow must be unrestricted.

    d. Verify that the vent is in good condition, properly sized and free from obstruction.

    e. Perform a combustion analysis (CO, O2, etc.) at both high and low fire, if possible. Record all data, as well as the following:

      (1) Inlet fuel pressure at burner at high and low firing rates.

      (2) Pressure above draft hood or barometric damper at high, medium and low firing rates.

      (3) Steam pressure, water temperature, or process fluid pressure or temperature entering and leaving the unit.

      (4) Inlet fuel use rate if meter is available.

  2. Checks & Corrections

    a. Clean all dirty burners or burner orifices. Verify that fuel filters and moisture traps are in place, clean, and operating properly. Confirm proper location and orientation of burner diffuser spuds, gas canes, etc. Replace or repair damaged or missing burner parts.

    b. Remove external and internal sediment and scale from heating surfaces.

    c. Verify that the necessary water or process fluid treatment is being used. Confirm flushing and/or blowdown schedule.

    d. Repair all leaks. In addition to the high-pressure lines, check the blow-off, drain, safety valve, bypass lines and, if used, the feed pump.

  3. Safety Checks

    a. Test primary and secondary low water level controls.

    b. Check operating and limit pressure and temperature controls.

    c. Check pilot safety shut off operation.

    d. Check safety valve pressure setting and verify that the setting is consistent with unit load requirements.

    e. Check limit safety control and spill switch.

  4. Adjustments

    Perform the following checks and adjustments on a warm unit at high fire:

    a. Adjust unit to fire at the maximum inlet fuel use rate: record fuel manifold pressure.

    b. Adjust draft and/or fuel pressure to obtain acceptable, clean combustion at both high, medium and low firing rates. The carbon monoxide (CO) value should not exceed 400 parts per million (PPM) at 3% O2.

    Verify that unit light-offs are smooth and safe. Perform a reduced fuel pressure test at both high and low firing rates in accordance with the manufacturers instructions.

    c. Check and adjust the modulation controller. Verify proper, efficient and clean combustion through the range of firing rates.

    When optimum performance has been achieved, record all data.

  5. Final Test

    Perform a final combustion analysis on the warm unit at high, medium and low firing rates, if possible. Record data obtained from combustion analysis, as well as the following:

    a. Inlet fuel pressure at burner at high and low firing rates.

    b. Pressure above draft hood or barometric damper at high, medium and low firing rates.

    c. Steam pressure, water temperature, or process fluid pressure or temperature entering and leaving the unit.

    d. Inlet fuel use rate if meter is available.


11. This tuning procedure is based on a tune-up procedure developed by KVB, Inc. for the EPA.

22. The smoke-spot number can be determined with ASTM Test Method D-2156 or with the Bacharach method.

33. Typical minimum oxygen levels for boilers at high firing rates are:


1. For natural gas: 0.5% - 3%

2. For liquid fuels: 2% - 4%