Combustion device
In accordance with the flow distribution of combustion gas including an unburned portion, an after-air port (AAP) arranged downstream of the two-stage combustion burner can effectively reduce the unburned portion by dividing as appropriate so as to avoid interaction, and by mixing together, two types of after-air having functions of linearity and spreading. As the configuration of this AAP, a primary nozzle for supplying primary after-air and having a vertical height greater than the horizontal width is provided in the center in the opening of the AAP, a secondary nozzle for supplying secondary after-air is provided in the opening outside of the primary nozzle, and one or more secondary after-air guide vanes having a fixed or variable tilt angle relative to the after-air port center axis are provided at the outlet of the said secondary nozzle to deflect and supply the secondary after-air horizontally to the left or right.
1. A combustion device in which burners are disposed on a furnace wall to burn fuel with an amount of air of theoretical air or less, and after-air ports to supply air are disposed on the furnace wall in the downstream side from the position where the burners are disposed, the combustion device characterized in that it comprises:
a primary after-air nozzle ( 5 ) which is provided at the central part in an opening ( 17 ) of the after-air port with larger vertical height than horizontal width to supply a primary after-air ( 1 );
secondary after-air nozzles ( 14 ) which are provided in the opening ( 17 ) of the after-air port at the outside of the primary after-air nozzle ( 5 ) to supply a secondary after-air ( 11 ); and
one or more pairs of secondary after-air guide vanes ( 15 ) which are provided in the outlet parts of the secondary after-air nozzles ( 14 ) and have inclination angles with respect to a central axis of the after-air port, so as to deflect the secondary after-air ( 11 ) right and left in the horizontal direction and supply the same.
2. The combustion device according to claim 1 , characterized in that the primary after-air nozzle ( 5 ) includes one or more primary after-air guide vanes ( 8 ) which are provided in the outlet part thereof and are configured to control an inclination angle thereof in the horizontal direction or upward from the horizontal direction, so as to supply the primary after-air ( 1 ) upward with an inclination angle.
3. The combustion device according to claim 1 , characterized in that the secondary after-air guide vanes ( 15 ) all have the same inclination angles with respect to the central axis of the after-air port.
4. The combustion device according to claim 1 , characterized in that each of the secondary after-air guide vanes ( 15 ) has a deviation in the inclination angles thereof with respect to the central axis of the after-air port.
5. The combustion device according to claim 4 , characterized in that the secondary after-air guide vanes ( 15 ) have inclination angles becoming larger with increasing distance away from the primary after-air nozzle ( 5 ) with respect to the central axis of the after-air port.
6. The combustion device according to claim 1 , characterized in that the secondary after-air guide vanes ( 15 ) are configured to change the inclination angles thereof.
7. The combustion device according claim 1 , characterized in that the secondary after-air guide vanes ( 15 ) are configured to move in the anteroposterior direction of the furnace wall.
8. The combustion device according to claim 1 , characterized in that a first guide member ( 16 ) is provided at a portion nearest the primary after-air nozzle ( 5 ), to supply a small amount of secondary after-air ( 11 ) along a surface of the secondary after-air guide vane ( 15 ) on the furnace side thereof and the outer surface of the tip part of the primary after-air nozzle ( 5 ).
9. The combustion device according to claim 1 , characterized in that the openings ( 17 ) of the after-air port have spreading parts ( 18 ) of a shape whose end spreads toward the furnace, and are respectively provided with second guide members ( 19 ) to supply a small amount of the secondary after-air ( 11 ) along surfaces of the spreading parts ( 18 ).
10. The combustion device according to claim 1 , characterized in that any one or both of an inlet part of the primary after-air nozzle ( 5 ) and inlet parts of the secondary after-air nozzles ( 14 ) are provided with air flow rate control functional members to change a flow path resistance.
11. The combustion device according to claim 1 , characterized in that the primary after-air nozzle ( 5 ) includes a contracting member ( 5 a ) having a flow passage cross-sectional area gradually decreased in a flow direction of air, which is attached to the inlet part thereof.
12. The combustion device according to claim 1 , characterized in that the primary after-air nozzle ( 5 ) includes a contracting member ( 5 b ) having a horizontal width gradually decreased in a flow direction of air, which is attached to the tip part thereof.
13. The combustion device according to claim 1 , characterized in that any one or both of the primary after-air nozzle ( 5 ) and the secondary after-air nozzles ( 14 ) include rectifiers installed in flow passages thereof.
14. The combustion device according to claim 1 , characterized in that the opening ( 17 ) of the after-air port is formed in a rectangular shape.
15. The combustion device according to claim 1 , characterized in that the opening ( 17 ) of the after-air port is formed in a polygonal shape.