Utility Boiler Operating Modes for Reduced Nitric Oxide Emissions

Predictions of NOx emissions in pulverized coal combustion.

“…Figure 40 shows the results. This control strategy was originally established for natural gas-fired systems where in particular NO x emissions were reduced by 15 % at full load with a 45 K reduction in combustion air temperature [218]. Principally the results in Figure 40 confirmed the general statement that with reducing the air preheat the NO x formation can be suppressed also for pulverized coal-fired systems which had already been identified to have relatively small reduction potentials [221].…”

“…Another found hint in the available literature regarding NO x control possibilities due to a change in the operational settings of a boiler is to reduce the preheat temperature of the hot combustion air [5,88,91,212,[218][219][220]. The theory is simple, since NO x emissions are influenced by the effective peak temperature of the combustion process would any change in that temperature profile result in a change in NO x emissions.…”

Controlling NOxEmissions From Steam Generators

“…These are actually duplicate 320-Mw, divided furnace units in the Southern California Edison (SCE) system and have been extensively tested as reported in Ref. 6.…”

“…Southern California Edison data 6 for the three 160-Mw furnaces were included to illustrate the effects of flue gas reeirculation to the windbox (as previously described under gas firing) and also the influence of chemically combined nitrogen in the fuel. The 160-Mw unit with an emission rate of 600 ppm was fired with California residual oil containing 1% nitrogen.…”

“…Flue gas reeirculation was also demonstrated as an effective means of controlling NO* emissions with gas firing by Southern California Edison. 6 Tests were conducted on one 250-Mw unit to establish the effects of air preheat and water injection on NO X emissions. Eliminating air preheat by stopping the rotation of the Ljungstrom air heater at 75% load reduced the NO X emission level from 200 to 100 ppm as air temperatures decreased from 490°t o 81°F.…”