Mechanism of pulverized coal preheating-combustion low-NOx reduction and synergistic control of particulate matter
Combustion optimal is expected to realize efficient low-NOx combustion of pulverized coal with synergistic control of particu-late matter(PM),and is also a crucial clean combustion method to accomplish low-carbon goals.To clarify the formation and reduc-tion mechanisms of NO and particulate matter(PM),the release of coal nitrogen,the conversion of volatile nitrogen,the NO formation and reduction mechanism,and the PM formation have been investigated during the preheating-combustion.The main gas components and PM were measured by a flue gas analyzer and an electrical low pressure impactor(ELPI+),respectively.The results indicate that the gas-phase excess air coefficient(αgas)serves as an effective criterion for the reactivity(oxidative or reductive)of the preheating zone,which predominantly involves gas-phase reactions.An increase in excess air coefficient(αp)slightly impairs the operation of the preheating zone,yet significantly enhances the reduction of NO during the entire preheating-combustion process.A higher preheating tem-perature notably decreases NO formation,with NO reduction efficiency increasing from 42.25％to 51.44％as preheating temperature rises from 1 200 K to 1 600 K.However,this effect diminishes with an increase in αp.Raising the temperature has a promoting effect on both char oxidation for NO formation and char reduction of NO,but the effect on NO formation is more pronounced.Concurrently,the pre-heating-combustion process reduces the of PM,particularly 27.57％reduction in PM03.The preheating-combustion technology can achieve the synergistic source control of PM and NO formation,which is important for the clean combustion of coal.
preheating-combustiongas-phase excess air coefficientnitrogen oxidesparticulate mattersynergistic control
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