Fluid sprinkling – spraying – and diffusing – Rigid fluid confining distributor – Having interior filter or guide
Reexamination Certificate
2000-05-15
2002-03-26
Douglas, Lisa Ann (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Rigid fluid confining distributor
Having interior filter or guide
C239S592000, C239S597000
Reexamination Certificate
active
06360973
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a spray nozzle for spraying a continuous casting product with a cooling liquid according to the preamble of claim
1
.
BACKGROUND OF THE INVENTION
As is known, in a continuous casting process, in particular for the continuous casting of steel, cooling of a metal melt in a continuous casting mould results in a continuous casting product which is continuously drawn out of the mould in the form of a strand whose surface is constituted by a solidified crust and which still has a liquid core of metal melt. After leaving the mould, the strand is conveyed through a secondary cooling zone in which it is sprayed with a coolant, generally water, in order to continue removing heat from it until it has completely solidified and bring it to the temperature desired for subsequent processing.
As secondary cooling directly causes the strand to solidify or influences its solidification, the secondary cooling process and the devices required to carry it out have a decisive effect on the quality of the end products. The components used to disperse the coolant, in particular the spray nozzles, are of particular importance.
The various parameters which characterise the secondary cooling process affect the solidification of the strand in different ways and—depending on the practice—must be optimised according to different criteria.
Particularly important factors are the secondary cooling intensity, which determines the speed of the strand shell growth and which is set to be more or less “harsh” or “gengentle”, depending on the practice, and the spatial distribution of the coolant application density, which should be as homogeneous as possible in order to ensure that the strand shell growth is as homogeneous as possible.
The spray nozzles used in a secondary cooling section to atomise a coolant are usually optimised with regard to the required standards of secondary cooling intensity and homogeneity of the coolant application. The kinetic energy of the cooling liquid droplets applied by spraying and, in particular, the coolant application density are in this respect determining factors for the secondary cooling intensity. The homogeneity of the coolant application density is not just determined by the homogeneity of the droplet dispersion in the spray jet produced by an individual spray nozzle. The angular distribution of the droplet paths is also relevant to the homogeneity of the coolant application density. Namely, the angular distribution determines the shape and the size of the area on a strand which can be sprayed with a spray jet. However a large number of spray nozzles are required in a secondary cooling zone in order to cover with coolant the entire area of a strand which is to be cooled. The spray jets of the individual nozzles are therefore superimposed accordingly. The angular distribution of the droplet paths of an individual spray jet is consequently a decisive factor for the homogeneity of the coolant application density when superimposing a large number of spray jets.
The known full cone nozzles deliver spray jets with a conical angular distribution of the droplet paths. Because of their conical shape, the spray jets of a plurality of full cone nozzles are unable to perfectly cover large areas for spraying; the superimposition of a plurality of spray jets results in a highly inhomogeneous coolant application density. A spray nozzle having all the features of the preamble of claim
1
is known from U.S. Pat. No. 3 072 346. This spray nozzle has a nozzle body with a mixing chamber which is rotationally symmetrical about the longitudinal axis of the nozzle body, into which chamber a liquid, forming a first and a second liquid stream, can flow through two inlet openings and which is provided with an outlet opening, disposed downstream, for a spray jet. Apart from the formation of the outlet opening, this nozzle has essential features of a known type of full cone nozzle: The two inlet openings are integrated into a guide structure for the liquid streams entering the mixing chamber such that a velocity component is imparted to the liquid streams tangentially to the mixing chamber wall as they enter the mixing chamber in addition to a velocity component in the direction of the outlet opening. This tangential velocity component causes the two liquid streams to combine after entering the mixing chamber to form one liquid stream which is directed at the outlet opening and which exhibits a vortex about the longitudinal axis of the nozzle body. Although the spray nozzle which is described in U.S. Pat. No. 3 072 346 has a round outlet opening—like a conventional full cone nozzle—, this outlet opening is widened like a funnel on the outlet side such that the emerging spray jet is distorted in the direction of the diagonals of a square. Because the outlet opening is formed in this way, the nozzle delivers a spray jet with an approximately square droplet dispersion related to a plane perpendicular to the longitudinal axis of the nozzle body.
One disadvantage of this spray nozzle is that, because of the vortex which is imposed, the form of the droplet dispersion of the spray jet is distorted to an increasing degree as the infeed pressure of the liquid increases. It is therefore impossible to comply with the standards required in terms of homogeneity of the coolant application density in a secondary cooling section with a nozzle of this kind.
A further disadvantage of this nozzle lies in the fact that its spray jet only has an approximately square droplet dispersion in one spray plane, which may not be very far away from the outlet opening, typically not more than 20 cm. Because of the short operating distance, a large number of spray nozzles of this kind are required to spray large areas with a sufficient degree of homogeneity.
BACKGROUND OF THE PRIOR ART
A flat-jet nozzle is described in U.S. Pat. No. 4 988 043. It comprises a passage for the liquid to be atomised with an outlet slot for the spray jet. The spray jet is fanned out over a wide angular range in the slot direction, whereas it hardly widens transversely to the longitudinal direction of the slot as the distance from the outlet slot increases. The quasi one-dimensional fan-out results in a flat spray jet. On account of the small extent of the spray jet transversely to the outlet slot, the process of spraying relatively large rectangular areas entails complications, whether because a large number of these flat-spray nozzles must be used or because a single flat-spray nozzle must be moved in order to cover a relatively large area with its spray jet.
OBJECT OF THE INVENTION
Taking the inadequacies of the known spray nozzles as a starting point, the object of the invention is to provide a spray nozzle which is suitable for use in a secondary cooling section of a continuous casting plant and for this purpose enables the largest possible area to be sprayed as homogeneously as possible with liquid droplets with the greatest possible kinetic energy from the greatest possible distance.
This object is achieved by a spray nozzle having the features of claim
1
.
The spray nozzle according to the invention comprises a mixing chamber into which a liquid, forming a first and a second liquid stream, can flow through two inlet openings and which comprises an outlet opening, disposed downstream, for a spray jet, wherein at least one mixing chamber wall is formed as a guide surface for the liquid streams and is shaped at the outlet opening such that the liquid streams meet at an angle at or directly before the outlet opening and then form the spray jet. Because the two liquid streams are directed at the outlet opening and collide at the outlet opening, relatively large liquid droplets are produced which—related to the infeed pressure at the inlet openings—can leave the outlet opening with a relatively high level of kinetic energy. Energy losses due to vortex formation in the mixing chamber are largely prevented. The high level of kinetic energy allows an area to be sprayed from a considerable working distance
Concast Standard AG
Darby & Darby
Douglas Lisa Ann
LandOfFree
Slot nozzle for spraying a continuous casting product with a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Slot nozzle for spraying a continuous casting product with a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Slot nozzle for spraying a continuous casting product with a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2840218