Prediction of NO<SUB>x</SUB> and unburned carbon in ash in highly staged pulverised coal furnace using overfire air

Unburned carbon from coal combustion ash: An overview

“…In addition to this, UC contents in FAs have increased considerably due to the implementation of stringent Clean Air Act Regulations regarding NO x emissions [4,6,11,12,58,[72][73][74]. For example, FA collected during PFC equipped with a low-NO x burner during the combustion of high volatile bituminous coal exhibited 59% LOI.…”

“…[4,5] -type and number of burners (especially installation of low-NO x burners) [6][7][8][9][10][11][12] -oxy-fuel combustion technology [13,14] -post-combustion of carbon residues in ash [15] -combustion temperature and pressure [16,17] -residence time available for combustion in furnace, boiler output [9,[18][19][20] -oxygen availability (air/coal ratio, excess air at the burner, primary to secondary air ratios) [9,16,[21][22][23][24][25][26][27][28][29]] -furnace heat loading, heat flow rates [24,26] -even/uneven flame patterns [30] -matching of operating conditions and raw-fuel quality [30].…”

CFD modelling of oxy-coal combustion in an entrained flow reactor

“…There is experimental evidence [9,10] that the reaction rate of char with oxygen is much higher than that of char with CO 2 and with H 2 O at flame temperatures. They are therefore often ignored in the simulations for pulverised fuel combustion, and there is some evidence for this even under flame-staging conditions [11], since under these conditions some regions have low oxygen concentrations where char gasification reactions might take place in addition to normal combustion. The objective of this work is to evaluate the effect of replacing N 2 by CO 2 on char burnout and gaseous species during coal combustion by means of a CFD model.…”

Experimental Investigation on Combustion and NOx Formation Characteristics of Low-Ash-Melting-Point Coal in Cyclone Furnace

“…Hence, the ultralow NO x formation can be obtained under high temperatures and strong reducing atmosphere. In fact, unlike the pulverized coal boilers and the circulating fluidized bed boilers for which it is difficult to simultaneously achieve both the strong reducing atmosphere and high-temperature conditions, the cyclone furnace can easily achieve both at the same time, which might be beneficial for achieving ultralow NO x formation. − However, most of the research related to NO x formation was carried out in drop tube electric heating furnaces, which cannot directly guide the situation of strongly swirling combustion in cyclone barrels.…”