Guide to Low-Emission Boiler and Combustion Equipment Selection C. B. Oland. DOCUMENT AVAILABILITY Reports produced after January 1, 1996, are generally available free via the 6.6 Emission control options for natural-gas-fired watertube and firetube boilers.. 6-12 6.7 Emission control options for biomass-fired, stoker-fed, watertube
Guide to Low-Emission Boiler and Combustion Equipment
Refineries have been mandated to reduce levels of sulfur, nitrogen and other pollutants in order to reduce emissions. Post-combustion control Post-combustion process control generally consists of the use of baghouses and filters in the case of solid fuel firing, and selective catalytic reduction (SCR) process to reduce NOx in gas and oil fired boilers.
exhaust system emission control. Only the inter-nal gas turbine emission control methods — lean head end liners and water/steam injection — will be covered in this paper. In the early 1970s when emission controls were originally introduced, the primary regulated gas turbine emission was NO x. For the relative-ly low levels of NO x reduction required in the
Selective non-catalytic reduction involves the injection of a NOx reducing agent, such as ammonia or urea, into the boiler exhaust gases at a temperature of approximately 1400-1600°F. The ammonia or urea breaks down the NOx in the exhaust gases into water and atmospheric nitrogen. Selective non-catalytic reduction reduces NOx up to 70%.
Fuel: Birmingham Natural Gas (1002 Btu/cu ft, 0.6 sp gr) Exhaust Gas Heat Loss, % of Input 0% Excess Air 3000 Exhaust Gas Temperature, °F Correct Ratio Process Efficiency Richer Leaner Air-Gas Ratio Figure 5. Effect of off-ratio operation on furnace efficiency. Figure 4. Exhaust gas heat losses vs. exhaust gas temperature and air-gas ratio.
Two postcombustion technologies that may be applied to natural gas-fired boilers to reduce NOx emissions are selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR). The SNCR system injects ammonia (NH3) or urea into combustion flue gases (in a specific temperature zone) to reduce NOx emission.
Flue Gas Recirculation: History and Uses - EnviroPower Renewable Inc.