PULVERIZED COAL FIRING METHOD, PULVERIZED COAL BOILER AND PULVERIZED COAL BURNER

摘要

PURPOSE:To facilitate to cope with load variation and achieve low NOx combustion by providing both a mixed gas flow channel for pulverized coal and primary air in mixture and a secondary air channel with a member which reduces the cross sections of the flow channels and jetting out tertiary air from a position away from the mixed gas channel as a swirl flow of high speed in order to form a strong recirculation flow on the side downstream of the member. CONSTITUTION:At the tip end of a mixed gas flow channel 2 for pulverized coal and primary air a flow channel cross section reducing member 3 is provided which projects also on the side of secondary air flow channel 5 and the tip end of a tertiary air flow channel 10 is positioned on the side downstream of the secondary air flow channel 5. With this constitution the tertiary air is jetted out into a furnace as a strong swirl flow from a position away from the mixed gas flow channel 2 to form a recirculation flow 15 on the downstream side of the member 3 and to form a high temperature area and a high concentration area of minute particles. Accordingly stable ignition and flame holding characteristics are achieved and a low oxygen area is formed from near the burner so that the concentration of NOx is very much lowered.