Furnaces – Including noncombustible fluid supply means
Reexamination Certificate
2000-02-15
2001-02-27
Lazarus, Ira S. (Department: 3743)
Furnaces
Including noncombustible fluid supply means
C110S348000, C110S343000, C431S010000
Reexamination Certificate
active
06192811
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an air nozzle for use in a coal-fired furnace and, more particularly, to such an air nozzle for discharging air into the interior of the furnace to support the combustion of coal discharged from a burner.
In coal fired furnace systems, a mixture of coal and air is usually discharged from one or more burners mounted relative to a furnace wall or walls, and secondary air is discharged from one or more air nozzles located adjacent each burner. Many types, arrangements and locations of the burners and the secondary air nozzles have been used. For example, in a conventional, straight firing system, the air nozzles are mounted relative to the furnace walls adjacent their associated burners in a manner to discharge the secondary air in a direction perpendicular to the walls. In tangential firing systems, the burners and the secondary air nozzles are disposed in each of the corners of the furnace and are designed specifically to discharge the fuel and the secondary air, respectively, towards an imaginary circle located in the center of the furnace. However, in these tangential firing arrangements, although a reducing atmosphere is often present along the inner surfaces of the boundary walls which causes corrosion and slagging, there is no provision for directing air from the air nozzles to the boundary walls. Therefore, what is needed is a secondary air nozzle for use in a tangentially fired furnace in which the nozzle directs secondary air both towards the center of the furnace to support the combustion of the fuel, and towards a furnace boundary wall to minimize corrosion and slagging.
SUMMARY OF THE INVENTION
The secondary air nozzle of the present invention is designed for use in furnace applications in which improvements are achieved by discharging the secondary air in two distinct flow patterns. To this end, the nozzle is provided with a damper blade that splits the air flow into two distinct discharge flow streams, which are directed into different areas of the interior of the furnace. The discharge pattern from the nozzle can be adjusted in accordance with the particular nozzle location and design requirements. When used with a tangentially fired furnace, one of the air flow streams is directed towards the center of the furnace in a combustion-supporting relationship to the fuel, and the other air flow stream is directed towards the inner surface of one of the boundary walls to maintain an oxidizing atmosphere along the inner surfaces of the furnace wall.
Thus, significant advantages are achieved with the secondary air nozzle of the present invention since it provides two distinct discharge streams for the secondary air, with the relative amount of air and the angle of discharge being variable.
REFERENCES:
patent: 5662464 (1997-09-01), LaRose et al.
patent: 5746143 (1998-05-01), Vatsky
Ciric Ljiljana V.
Foster Wheeler Corporation
Haynes and Boone LLP
Lazarus Ira S.
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