EL DORADO COUNTY AIR QUALITY MANAGEMENT DISTRICT

RULE 229 - INDUSTRIAL, INSTITUTIONAL, AND COMMERCIAL BOILERS, STEAM GENERATORS, AND PROCESS HEATERS
(Amended: January 23, 2001)

229.1 GENERAL

  A. PURPOSE: To provide a control measure to limit emissions of NOx from industrial, institutional, and commercial boilers, steam generators and process heaters in conformance with BARCT determinations approved by the California Air Resources Board to meet the requirements of the California Clean Air Act.
  B. APPLICABILITY: This rule applies to boilers, steam generators, and process heaters with rated heat inputs of greater than or equal to 5 million BTU per hour, used in all industrial, institutional, and commercial operations.
  C. EXEMPTION, NONGASEOUS FUELS: Units subject to the requirements of Section 229.3 A. of this rule which normally burn only gas shall comply with a 150 ppmv, or 0.215 pound per million BTU of heat input, NOx emission when burning nongaseous fuel, if gas is unavailable for purchase. This exemption is limited to not more than 168 hours of operation per calendar year, excluding equipment and emission testing time not exceeding 48 hours per calendar year.
  D. EXEMPTION, ELECTRIC UTILITY BOILERS: The provisions of this rule does not apply to boilers used by electric utilities to generate electricity.
  E. EXEMPTION: WASTE HEAT RECOVERY BOILERS: The provisions of this rule do not apply to waste heat recovery boilers that are used to recover sensible heat from the exhaust of combustion turbines.
  F. EXEMPTION, DRYERS: The provisions of this rule do not apply to dryers in which the material being dried is in direct contact with the products of combustion.
  G. EXEMPTION, CEMENT AND LIME KILNS, GLASS MELTING FURNACES, AND SMELTERS: The provisions of this rule do not apply to cement and lime kilns, glass melting furnaces and smelters.
  H. EXEMPTION, BIOMASS BOILERS: The provisions of this rule do not apply to boilers subject to Rule 232, Biomass Boilers.
229.2 DEFINITIONS
  A. ANNUAL HEAT INPUT: The total heat input of fuels burned by a unit in a calendar year, as determined from the HHV and cumulative annual usage of each fuel.
  B. BARCT: "Best Available Retrofit Control Technology" as defined in section 40406 of the California Health and Safety Code as "an emission limitation that is based on the maximum degree of reduction achievable, taking into account environmental, energy, and economic impacts by each class or category of source".
  C. BOILER OR STEAM GENERATOR: Any combustion equipment fired with any fuel and used to produce steam that is not used exclusively to produce electricity for sale. This definition does not include any waste heat recovery boiler that is used to recover sensible heat from the exhaust of a combustion turbine.
  D. BRITISH THERMAL UNIT (BTU): The amount of heat required to raise the temperature of one pound of water from 59oF to 60oF at one atmosphere.
  E. GAS: Any fuel which is a gas at standard conditions
  F. HEAT INPUT: The chemical heat released due to fuel combustion in a unit, using the higher heating value of the fuel. This does not include the sensible heat of incoming combustion air.
  G. HIGHER HEATING VALUE (HHV): The total heat liberated per mass of fuel burned (BTU per pound), when fuel and dry air at standard conditions undergo complete combustion and all resultant products are brought to their standard states at standard conditions. HHV shall be determined by one of the following test methods:
    1. ASTM D 2015-85 for solid fuels; or
    2. ASTM D 240-87 or ASTM D 2382-82 for liquid hydrocarbon fuels; or
    3. ASTM D 1826-88 or ASTM D 1945-81 in conjunction with ASTM D 3588-89 for gaseous fuels.
  H. NOx EMISSIONS (NOx): The sum of nitric oxides and nitrogen dioxide in the flue gas.
  I. NONGASEOUS FUEL: Any fuel which is not a gas at standard conditions.
  J. PARTS PER MILLION (BY VOLUME) (ppmv): The ratio of the number of gas molecules of a given species, or group, to the number of millions of total gas molecules.
  K. PROCESS HEATER: Any combustion equipment fired with any fuel, and which transfers heat from combustion gases to water or process streams. This definition does not include any dryers in which the material being dried is in direct contact with the products of combustion, cement or lime kilns, glass melting furnaces, or smelters.
  L. RATED HEAT INPUT: The heat input capacity, in million BTU per hour, 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 maximum heat input shall be considered as the rated heat input.
  M. STANDARD CONDITIONS: A gas temperature of 68oF and one atmosphere and a gas pressure of 14.7 pounds per square inch absolute.
  N. THERM: One hundred thousand (100,000) BTU.
  O. THREE PREVIOUS CALENDAR YEARS: The three consecutive years immediately preceding the year in which final compliance is required by this rule, or the three consecutive years immediately preceding each calendar year of compliance thereafter.
  P. UNIT: Any boiler, steam generator or process heater as defined in Sections 229.2 C. and 229.2 K. of this rule.
The above conditions are referred to as the CO or smoke-spot thresholds, or as the minimum excess oxygen levels. 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 manufacturer, burner adjustments can probably be made to improve fuel and air mix, thereby allowing operations with less air.

229.3 STANDARDS

  A. ANNUAL HEAT INPUTS > 90,000 THERMS: For units with rated heat inputs of greater than or equal to 5 million BTU per hour and annual heat inputs of greater than or equal to 90,000 therms for any of the three previous calendar years, NOx emissions shall not exceed the following levels:
    1. 30 parts per million by volume (ppmv), or 0.036 pound per million BTU of heat input when operated on gas; or
    2. 40 parts per million by volume (ppmv), or 0.052 pound per million BTU of heat input, when operated on nongaseous fuel; or
    3. the heat-input weighted average of the limits specified in 229.3 A.1. and 229.3 A.2., above, when operated on combinations of gas and nongaseous fuels.
    Emissions from units subject to this Section shall not exceed a carbon monoxide concentration of 400 parts per million by volume (ppmv).
  B. ANNUAL HEAT INPUTS < 90,000 THERMS: Units with rated heat inputs of greater than or equal to 5 million BTU per hour and annual heat inputs of less than 90,000 therms for each of the three previous calendar years or units with rated heat inputs of greater than or equal to 5 million BTU per hour and not subject to the provisions of Section 229.3 A., shall:
    1. Be operated in a manner that maintains stack-gas oxygen concentrations at less than or equal to 3.00 percent by volume on a dry basis; or
    2. Be operated with a stack-gas oxygen trim system set at 3.00 percent by volume oxygen. The tolerance of this setting shall be plus or minus (") five percent (i.e. 2.85 to 3.15 per cent by volume oxygen); or
    3. Be tuned at least once per year by a technician that is qualified, to the satisfaction of the Air Pollution Control Officer, to perform a tune-up in accordance with Section 229.6 of this rule; or
    4. Be operated in compliance with the applicable emission levels specified in Section 229.3 A. of this rule.
  C. EQUIPMENT REQUIREMENTS
    1. Owners or operators of units which simultaneously fire combinations of different fuels, and are subject to the requirements of Section 229.3 A., shall install non-resettable totalizing mass flow rate meters in each fuel line. Alternatively, non-resettable totalizing volumetric flow rate meters may be installed in conjunction with temperature and pressure meters in each fuel line.
    2. Owners or operators of units which employ flue-gas NOx reducing technology and subject to the requirements of Section 229.3 A. of this rule, shall install meters, as applicable, to allow instantaneous monitoring of the operational characteristics of the NOx reduction equipment.

229.4 ADMINISTRATIVE REQUIREMENTS

  A. COMPLIANCE SCHEDULE: The owner or operator of units subject to this rule shall fulfill the following increments of progress:
    1. Submit, by September 27, 1996, a plan containing the following:
      a. A list of all units with their rated heat inputs and anticipated annual heat inputs.
      b. For owners or operators of units subject to section 229.3 A., for each unit listed, the selected method of achieving the applicable standard or standards of Section 229.3 A.
      c. For owners or operators of units subject to Section 229.3 B., for each unit listed, a selection of one of the four options specified in Section 229.3 B. to achieve compliance with this rule.
    2. All owners or operators subject to the provisions of this rule shall submit an application for Authority to Construct for any modifications required to achieve compliance with the requirements of this rule no later than September 27, 1996.
    3. By September 27, 1998, demonstrate final compliance with all applicable standards and requirements of this rule.
  B. COMPLIANCE DETERMINATION:
    1. An owner or operator of any unit(s) shall have the option of complying with either the pounds-per-million-BTU emission rates or the parts-per-million-by-volume emission limits specified in Section 229.3 A.
    2. All emission determinations shall be made in the as-found operating condition, except that emission determinations shall include at a minimum at least one source test conducted at the maximum firing rate allowed by the District permit, and no compliance determination shall be established within two hours after a continuous period in which fuel flow to the unit is zero, or shut off, for thirty minutes or longer.
    3. All ppmv emission limits specified in Sections 229.1 C. and 229.3 A. are referenced at dry stack-gas conditions and 3.00 percent by volume stack-gas oxygen. Emission concentrations shall be corrected to 3.00 percent oxygen as follows:


    4. All pounds-per-million-BTU emission rates shall be calculated as pounds of nitrogen dioxide (NO2) per million BTU of heat input.
    5. All emission concentrations and emission rates shall be based on 15-consecutive-minute averages. These averages shall be calculated from no less than five data sets, recorded from samplings on intervals of no greater than three minutes.
    6. All units covered under Sections 229.3 A. and 229.3 B. shall conduct source tests to demonstrate initial compliance with the requirements of these Sections. Additional source testing shall be required at least once every 12 month period to ensure compliance with the standards set forth in Sections 229.3 A. and 229.3 B. of this rule. Units covered under Section 229.3 B.3. shall be tuned not less than once every 12 months.
    7. A violation of the plan under Section 229.4 A.1. shall constitute a violation of this rule.
    8. The cumulative annual usage of each fuel shall be monitored from utility service meters, purchase, or tank fill records, or by any other acceptable methods approved by the Air Pollution Control Officer.
  C.  TEST REPORTS: The owners or operators of units subject to Section 229.3 of this rule shall submit compliance test reports on each unit for each fuel burned, including any fuels which may be burned in accordance with Section 229.1 C., not less than once every twelve months; except that tune-up verification reports shall be submitted not less than once every twelve months for each unit complying with Section 229.3 B.3. for each fuel burned. Test reports shall include the operational characteristics of all flue-gas NOx reduction equipment. The first test or tune-up report, for each unit subject to Section 229.3 of this rule shall be submitted by September 27, 1998.

229.5 MONITORING AND RECORDS

   A. FUEL USAGE AND OPERATING HOURS: The owners or operators of units subject to Section 229.3 of this rule shall monitor and record for each unit the HHV and cumulative annual usage of each fuel. The owners and operators of units exempt from Section 229.3 A. in accordance with Section 229.1 C. shall monitor and record for each unit the cumulative hours of operation on each nongaseous fuel. The records shall be updated weekly and made available to the District upon request. Historical annual data for the three previous calendar years shall be kept and made available by the owners and operators.

  B. TEST METHODS:
    1. Compliance with NOx emission requirements and the stack-gas carbon monoxide and oxygen requirements of Section 229.3 shall be determined using the following test methods:
      a. Oxides of Nitrogen - ARB Method 100.
      b. Carbon Monoxide - ARB Method 100.
      c. Stack-Gas Oxygen - ARB Method 100.
      d. NOx Emission Rate (Heat Input Basis) - EPA Method 19.
    2. Integrated sampling methods for oxides of nitrogen, stack-gas oxygen, and stack-gas carbon monoxide, as approved by the Air Pollution Control Officer, California Air Resources Board and the United States Environmental Protection Agency, may be acceptable for determination of compliance with NOx emission concentration or rate limits.

229.6 TUNING PROCEDURE

   A.  GENERAL: Nothing in this tuning procedure1 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 Insurors, 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.
  B. PROCEDURES:
    1. Operate the unit at the firing rate most typical of normal operation. If the unit experiences significant load variations during normal operations, operate the unit at its average firing rate.
    2. At the firing rate established in Section 229.6 B.1., record stack-gas temperatures, oxygen concentration, and CO concentration (for gaseous fuels) or smoke-spot number2 (for liquid fuels), and observe flame conditions after unit operation stabilizes at the selected firing rate. If the excess oxygen in the stack-gas is at the lower range of typical minimum values3, and if CO emissions are low and there is no 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 until the stack-gas oxygen levels increase by one or two percent over the level measured in Section 229.6 B.2. As in Section 229.6 B.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 unit operation stabilizes.
    4. Decrease combustion air flow until the stack-gas oxygen is at the level measured in Section 229.6 B.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 the following limits is reached:
      a. Unacceptable flame conditions - such as flame impingement on furnace walls or burner parts, excessive flame carryover, or flame instability;
      b. Stack-gas CO concentrations greater than 400 ppm;
      c. Smoking at stack;
      d. Equipment-related limitations - such as low windbox/furnace pressure differential, built-in air-flow limits, etc.
    6. Develop an O2/CO curve (for gaseous fuels) or O2/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 Section 229.6 B.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 and #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 the CO or smoke-spot thresholds, or as the minimum excess oxygen levels. 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 manufacturer, burner adjustments can probably be made to improve fuel and air mix, thereby allowing operations with less air.

    8. Add 0.5 to 2.0 percent to the minimum excess oxygen level found in Section 229.6 B.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 Sections 229.6 B.1. - 229.6 B.8. for the 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 the best performance over the range of the firing rates. If one firing rate predominates, the setting should optimize the conditions at the rate.
    10. Verify that the new settings can accommodate the sudden load 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 Section 229.6 B.5. result, reset the combustion controls to provide a slightly higher level of excess oxygen at the affected 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.

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1. THIS TUNING PROCEDURE IS BASED ON A TUNE-UP PROCEDURE DEVELOPED BY KVB, INC. FOR THE EPA.
2. THE SMOKE-SPOT NUMBER CAN BE DETERMINED WITH ASTM TEST METHOD D-2156 OR WITH THE BACHARACH METHOD. THE BACHARACH METHOD IS INCLUDED IN A TUNE-UP KIT THAT CAN BE PURCHASED FROM THE BACHARACH COMPANY.
3. TYPICAL MINIMUM OXYGEN LEVELS FOR UNITS AT HIGH FIRING RATES ARE:
A. FOR NATURAL GAS: 0.5 - 3%
B. FOR LIQUID FUELS: 2 - 4%.














Figure 1

Oxygen/CO Characteristic Curve























Figure 2

Oxygen/Smoke Characteristic Curve


















SOURCE: KVB INC.