Effect of Air-Staging on Anthracite Combustion and NO_x Formation

Abstract

Experiments were carried out in a multipath air inlet one-dimensional furnace to assess NO x emission characteristics of the staged combustion of anthracite coal. These experiments allowed us to study the impact of pulverized coal fineness and burnout air position on emission under both deep and shallow air-staged combustion conditions. We also studied the impact of char-nitrogen release on both the burning-out process of the pulverized coal and the corresponding carbon content in fly ash. We found that air-staged combustion affects a pronounced reduction in NO x emissions from the combustion of anthracite coal. The more the air is staged, the more NO x emission is reduced. In shallow air-staged combustion (f M ) 0.85), the fineness of the pulverized coal strongly influences emissions, and finer coals result in lower emissions. Meanwhile, the burnout air position has only a weak effect. In the deep air-staged combustion (f M ) 0.6), the effect of coal fineness is smaller, and the burnout air position has a stronger effect. When the primary combustion air is stable, NO x emissions increase with increasing burnout air. This proves that, in the burnout zone, coal char is responsible for the discharge of fuel-nitrogen that is oxidized to NO x . The measurement of secondary air staging in a burnout zone can help inhibit the oxidization of NO caused by nitrogen release. Air-staged combustion has little effect on the burnout of anthracite coal, which proves to be suitable for air-staged combustion.

NO Emissions and Combustion Efficiency during Biomass Co-firing and Air-staging

“…Fan et al (2008;2010) investigated the effect of air staging on the NOx emission of anthracite and lignite at 1300 °C in a multi-path air inlet one-dimensional furnace. It was observed that the air-staging ratio had a great effect on NOx formation, and NOx emission decreased with the decrease in stoichiometric ratio of 1.5 to 1.0.…”

Experimental Study on Nitrogen Transformation in Combustion of Pulverized Semi-coke Preheated in a Circulating Fluidized Bed

“…18,19 Therefore, NO in the DFC was mainly transformed by the fuel-N and NH 3 . Figure 11 shows the profiles of NO concentration along the axis of the DFC under different conditions of the secondary air nozzles.…”

Penetration behavior of opposed rows of staggered secondary air jets depending on jet penetration coefficient and momentum flux ratio

“…Nasserzadeh et al indicated that the modification of the secondary air orifice can help reduce emissions and optimize the overall plant performance of the incinerator [4,5]. The reduction of NOx emissions has also been achieved on the basis of the air staging conditions in the wall-fired boiler [6][7][8]. Some researchers described the importance of the secondary air jet configuration on the flow path and temperature distributions through CFD analyses [8][9][10][11].…”