The combustion behavior of pulverized coal in high temperature air combustion condition has been studied using a regenerative type furnace. High temperature air over 1073K is produced by a heat regenerator made by ceramic heat storage honeycombs. A square shaped furnace of 1.6m length and 0.9m, 0.6m cross section is used in the experiment. In order to control the ash deposition on the honeycombs, cyclone and soot blowing by compressed air are used. Two kinds of pulverized coal (fuel ratio = 2.1 and 7.4) are fed into the furnace at the rate of 7kg/h continuously along the center of the furnace. Excess air ratio is changed from 1.0 to 1.5. Pulverized coal flame behavior is recorded by CCD camera, and the temperature distribution in the furnace is measured by thermocouple. Composition of the exhaust gas is measured by a gas analyzer. From the results, pulverized coal flame is stabilized by high temperature air even for high fuel ratio coal. NO_x concentration in the exhaust gas is reduced to 100ppm (6 percent O_2) which seems to be much lower than in the usual pulverized coal combustion condition where air temperature is about 623K. It is confirmed that the advantage of high temperature air combustion of pulverized coal is that both stable flame and enhanced reduction zone near the burner can be achieved by the improvement of ignition behavior. Ash deposition on the heat exchanger mainly occurs on the surface of the honeycombs, and can be controlled using cyclone and soot blowing technique.
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