Considerable research efforts focus on modeling NO
x
formation/destruction and predicting NO
x
emission so that it can be controlled. A
motivation
for this numerical study was to examine the efficiency of combustion
modifications in the furnaces of Kostolac B 350 MWe boiler units,
tangentially fired by pulverized lignite. Numerical analysis was done
by an in-house developed NO
x
submodel,
coupled with differential comprehensive combustion model, previously
developed and validated. The NO
x
submodel
focuses on homogeneous reactions of both the fuel and the thermal
NO formation/destruction processes. The submodel was validated by
comparison of predicted NO
x
emissions
with available measurements at the boiler units. Selected predictions
of the emission, the furnace exit gas temperature, NO concentration,
gas temperature, and velocity field are given for the case-study furnace
under different operating conditions. The individual or combined effects
of coal and preheated air distribution over the individual burners
and the burner tiers, the grinding fineness and quality of coal, and
the cold air ingress were investigated. Reduced emissions of up to
20–30% can be achieved only by proper organization of the combustion
process. Obtained results were verified by the boiler thermal calculations.
An optimal range of the furnace exit gas temperatures was proposed,
with respect to the safe operation of the steam superheater. Simulations
by means of a computer code developed for the purpose, showed that
the air staging using overfire air ports might provide the NO
x
emission reduction of up to 24% in the test-cases
with relatively high emission and up to 7% of additional reduction
in already optimized cases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.