SANTA BARBARA COUNTY AIR POLLUTION CONTROL DISTRICT
RULE 342 - CONTROL OF OXIDES OF NITROGEN (NOx) FROM BOILERS, STEAM GENERATORS AND PROCESS HEATERS
(Adopted 3/10/1992, revised 04/17/1997)
This rule applies to boilers, steam generators, and process heaters with rated heat inputs greater than or equal to 5 million Btu per hour used in all industrial, institutional, and commercial operations.
b. process heaters, kilns, and furnaces where the products of combustion come into direct contact with the material to be heated.
c. waste heat recovery boilers that are used to recover heat from the exhaust of combustion turbines or reciprocating internal combustion engines.
d. equipment that does not require a permit under the provisions of Rule 202.
2. Boiler or Steam Generator means any external combustion equipment fired with any fuel used to produce hot water or steam.
3. Higher Heating Value (HHV) means 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 standard conditions.
4. Process Heater means any external combustion equipment fired with liquid and/or gaseous fuel and which transfers heat from combustion gases to water or process streams.
5. Rated Heat Input (million Btu per hour) means the heat input capacity specified on the nameplate of the combustion unit. If the combustion unit has been physically modified such that its maximum heat input is different than the heat input capacity specified on the nameplate, the modified maximum heat input shall be considered as the rated heat input. The modified maximum heat input capacity shall be demonstrated to the District by a fuel meter while operating the unit at maximum capacity.
6. Unit means any boiler, steam generator or process heater as defined in 2 and 4 above.
D. Requirements - Emission Standards
b. 40 parts per million by volume or 0.052 pound per million Btu of heat input when operated on nongaseous fuel.
c. the heat-input weighted average of the limits specified in a. and b., above, when operated on combinations of gas and nongaseous fuel.
2. Units with rated heat inputs of greater than or equal to 5 million Btu per hour and permitted annual heat inputs of less than 9 billion Btu's shall be:
b. operated with a stack-gas oxygen trim system set at 3.00 ±0.15 percent oxygen by volume on a dry basis; or
c. tuned at least once every twelve months in accordance with the procedure described in Attachment 1; or
d. operated in compliance with the applicable emission levels specified in Subsection D.1.
E. Requirements - Equipment
2. Owners or operators of units which employ flue-gas NOx reduction technology, and are subject to the requirements of section D.1, shall install meters as applicable to allow instantaneous monitoring of the operational characteristics of the NOx reduction equipment.
3. The use of anhydrous ammonia to meet the requirements of this rule is prohibited.
F. Requirements - Compliance Determination
2. All ppmv emission limits specified in Subsection D.1 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:
3. All pounds-per-million-Btu NOx emission rates shall be calculated as pounds of nitrogen dioxide per million Btu of heat input.
G. Requirements - Testing
2. The owner or operator of any unit which is found not to be in compliance with Section D as a result of a source test shall comply with the following:
b. Annual source tests shall be conducted on any noncompliant unit until two consecutive tests demonstrate compliance with Section D. When the unit is demonstrated to be in compliance with Section D by two consecutive source tests, the unit shall comply with the provisions of Section G.1.
H. Test Methods
Compliance with the NOx emission requirements and the stack-gas carbon monoxide and oxygen requirements of section D shall be determined using the following test methods.
2. Carbon Monoxide - EPA Method 10.
3. Stack Gas Oxygen - EPA Method 3 or 3A.
4. NOx Emission Rate (Heat Input Basis) - EPA Methods 2 and 4 if applicable, or 19.
5. If certification of the HHV is not provided by the third party fuel supplier, it shall be determined by one of the following test methods: (1) ASTM D 2015-85 for solid fuels; (2) ASTM D 240-87 or ASTM D 2382-88 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.
For numbers 1, 2, 3 and 4 above there shall be a minimum of three 40 minute tests with a strip chart recorder. For instrument methods, the maximum data reduction averaging interval is ten minutes, i.e. four or more intervals per test run. Compliance is determined via the arithmetic mean of the three runs.
2. The owners and operators of units operating under the exemption of Section D.1.d shall monitor and record for each unit the cumulative annual hours of operation on each nongaseous fuel. This data shall be updated monthly.
3. The owners and operators of units operated under the provisions of section D.2.c shall maintain documentation verifying the required tuneups.
4. The records required above shall be kept for three calendar years and shall be made available to the District on request.
J. Reporting Requirements
The owners and operators of units subject to Sections D1, D.2.a, D.2.b, and D.2.d shall submit compliance test reports on each unit for each fuel burned. Test reports shall include operational characteristics of all flue-gas NOx reduction equipment or technology.
K. Compliance Schedule
The owner or operator of units subject to this rule shall:
2. By March 10, 1994 submit a plan containing the following:
b. For each unit listed, the selected method for meeting the applicable requirements.
4. By March 10, 1996 demonstrate final compliance with this Rule.
2. At this firing rate, record stack gas temperature, oxygen concentration, and CO concentration (for gaseous fuels) or smokespot number(2) (for liquid fuels), and observe flame conditions after unit operation stabilizes at the firing rate selected. If the excess oxygen in the stack i as is at the lower end of the range of typical minimum values(3) , 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:
b. Stack gas CO concentrations greater than 400 ppm.
c. Smoking at the stack.
d. Equipment-related limitations - such as low windbox/furnace pressure differential, built in air-flow limits, etc.
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:
|Gaseous||CO Emissions||400 ppm|
|#1 & #2||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|
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 nev settings in a similar fashion. Then make sure that the final control settings are recorded at steady-state operating conditions for future reference.
1 1. This tuning procedure is based on a tune-up procedure developed by KVB, Inc. for the EPA.
2 2. The smoke-spot number can be determined with ASTM Test Method D-2156 or with the Bacharach method. ASTM Test Method D-2156 is included in a tuneup kit that can be purchased from the Bacharach Company.
3 3. Typical minimum oxygen levels for boilers at high firing rates are:
2. For liquid fuels: 2% - 4%