Pulverized coal combustion burner

A pulverized coal combustion burner comprising

• a pulverized coal passage through which a mixture containing pulverized coal and air flows;
• an air passage through which additional air is supplied to a flow of said mixture from outside;
• a wall separating said pulverized coal passage from said air passage;
• first recirculation flow-forming means provided at a downstream end of said wall for forming recirculation flows of said mixture and said additional air;
• a separation wall provided within said pulverized coal passage for dividing said mixture flow into two straight flows;
• and
• second recirculation flow-forming means for forming recirculation flows of said mixture downstream of a downstream end of said separation wall, said second recirculation flow-forming means being constituted by an end surface of said separation wall extending perpendicular to said straight flows, a thickness of the end surface of said separation wall in a direction perpendicular to said straight flows being not less than 10 mm.

A pulverized coal combustion burner comprising:

• a pulverized coal passage through which a mixture containing pulverized coal and air flows;
• an air passage for supplying additional air to a flow of said mixture from outside;
• a wall separating said pulverized coal passage from said air passage;
• first recirculation flow-forming means provided at a downstream end of said wall for forming recirculation flows of said mixture and said additional air;
• a separation wall provided within said pulverized coal passage for dividing a flow of the mixture into two straight flows;
• and
• second recirculation flow-forming means for forming recirculation flows of said mixture downstream of a downstream end of said separation wall, one of said two straight flows of the mixture contains a relatively large amount of coarse pulverized coal, while the other straight flow contains a relatively a large amount of fine pulverized coal, said device further comprising a coarse pulverizer and a fine pulverizer, wherein one of said straight flows is in communication with said coarse pulverizer while the other straight flow is in communication with said fine pulverizer.

A pulverized coal combustion burner comprising:

• a pulverized coal passage through which a mixture containing pulverized coal and air flows;
• an air passage for supplying additional air to a flow of said mixture from outside;
• a wall separating said pulverized coal passage from said air passage;
• first recirculation flow-forming means provided at a downstream end of said wall for forming recirculation flows of said mixture and said additional air;
• a separation wall provided within said pulverized coal passage for dividing a flow of the mixture into two straight flows;
• and
• second recirculation flow-forming means for forming recirculation flows of said mixture downstream of a downstream end of said separation wall, one of said two straight flows of the mixture contains a relatively large amount of coarse pulverized coal, while the other straight flow contains a relatively a large amount of fine pulverized coal, said device further comprising a coal pulverizer for pulverizing coal, and a classifier for classifying the pulverized coal fed from said coal pulverizer, wherein the pulverized coal from said classifier which contains a relatively large amount of coarse coal particles is fed to said one straight flow, while the pulverized coal from said classifier which contains a relatively large amount of fine coal particles is fed to said other straight flow.

A pulverized coal combustion burner comprising:

• a pulverized coal passage through which a mixture containing pulverized coal and air flows;
• an air passage for supplying additional air to a flow of said mixture from outside;
• a wall separating said pulverized coal passage from said air passage;
• first recirculation flow-forming means provided at a downstream end of said wall for forming recirculation flows of said mixture and said additional air;
• a separation wall provided within said pulverized coal passage for dividing a flow of the mixture into the straight flows;
• and
• second recirculation flow-forming means for forming recirculation flows of said mixture downstream of a downstream end of said separation wall, said air passage comprising a secondary air passage annularly surrounding said pulverized coal passage and a tertiary air passage provided outside said secondary air passage;
• said burner further comprising means for swirling the mixture flowing in said pulverized coal passage and means for converting said swirling mixture into a straight flow and said pulverized coal passage having a circular transverse cross-section, said separation wall having an annular transverse cross-section, said mixture flow being divided into two concentric straight flows, and said converting means having plate-like members extending radially between said wall separating said pulverized coal passage from said air passage and said separation wall.