Natural gas boilers operate at lower excess air (O2) and a different airflow requirement for stoichiometric combustion. Coal fired boilers normally operate with 3-3.5% O2 (about 20% excess air). Whereas natural gas boilers normally operate at 1-1.5% O2 (about 7% excess air).
Industrial, Commercial, Institutional (ICI) boilers and process heaters Final air toxics standards for majorsources Applies to coal, oil, biomass (i.e., wood products), natural gas, refinery gas boilers and process heaters Code of Federal Regulations (CFR) 63.7480 through 63.7575 • NESHAPs Subpart 63 Subpart JJJJJJ (6J) GACT
The emissions from natural gas-fired boilers and furnaces include nitrogen oxides (NOx), carbon monoxide (CO), and carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), volatile organic compounds (VOCs), trace amounts of sulfur dioxide (SO 2 ), and particulate matter (PM).
(MMBtu) of natural gas while producing 45,000 lb/hour of 150-psig steam. Stack gas measurements indicate an excess air level of 44.9% with a flue gas minus combustion air temperature of 400°F. From the table, the boiler combustion efficiency is 78.2% (E1). Tuning the boiler reduces the excess air to 9.5% with a flue gas minus combustion
Expressed as NO2. For large and small wall-fired boilers with SNCR control, apply a 24% reduction to the appropriate NOx emission factor. For tangential-fired boilers with SNCR control apply a 13% reduction to the appropriate NOx emission factor.
Traditionally, the control system of a domestic boiler is conceived in such a way to regulate simply the water temperature by acting on the gas flow. Actually, in order to improve the quality of
In order to compare NOx concentrations on an equivalent basis, the field measured readings are corrected to a reference oxygen concentration. This reference concentration is typically 3% oxygen (dry volume basis) for boiler applications. If this correction is not applied, the NOx concentrations could simply be reduced by dilution with air although this would not reduce the quantity of emissions into the