The combustion behavior of pulverized coal in high temperature air combustioncondition has been studied using a regenerative type furnace.High temperature air over1073K is produced by a heat regenerator made by ceramic heat storage honeycombs.A squareshaped furnace of 1.6m length and 0.9m * 0.6m cross section is used in the experiment.Inorder to control the ash deposition on the honeycombs,cyclone and soot blowing bycompressed air are used.Two kinds of pulverized coal (fuel ratio = 2.1 and 7.4) are fed intothe furnace at the rate of 7kg/h continuously along the center of the furnace.Excess air ratio ischanged from 1.0 to 1.5.Pulverized coal flame behavior is recorded by CCD camera,and thetemperature distribution in the furnace is measured by thermocouple.Composition of theexhaust gas is measured by a gas analyzer.From the results,pulverized coal flame is stabilized by high temperature air even forhigh fuel ratio coal.Nox concentration in the exhaust gas is reduced to 100ppm (6%O2)which seems to be much lower than in the usual pulverized coal combustion condition whereair temperature is about 623K.It is confirmed that the advantage of high temperature aircombustion of pulverized coal is that both stable flame and enhanced reduction zone near theburner can be achieved by the improvement of ignition behavior.Ash deposition on the heatexchanger mainly occurs on the surface of the honeycombs,and can be controlled usingcyclone and soot blowing technique.
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