EP0013230B1 - Device for removing a fluid from the surface of a long and continuously moving product - Google Patents

Description

The present invention relates to a device for separating a long product in movement from a liquid envelope which accompanies it in the form of a coaxial jet.

The need for such a device is encountered, for example, at the outlet of a cooling device essentially comprising a tube traversed by a cooling liquid (usually water) and in the axis of which also circulates a product which is long to cool. The tube comprises, at one of its ends, a head for supplying cooling liquid and, at the other end, a separator whose role is to get rid, at the exit of the tube, of the product in movement of the liquid jet who envelops him.

Without being of application limited to certain particular industrial fields, such devices are encountered in particular in the steel industry, for example in continuous casting or more especially in the context of special heat treatments, for rapidly and vigorously cooling long products at the end of rolling. Faced with these cooling requirements, we quickly realized the need to provide, at the outlet of the tube, an element which, while ensuring free passage for the product moving in a straight line, allows recovery and evacuation coolant by interrupting, preferably over the shortest possible distance for reasons of space, the liquid envelope, which would otherwise exit the tube in a powerful jet which can easily reach ten meters and which, moreover, would make more difficult to control the cooling process.

To do this, it has already been proposed as a separator consisting of a simple box, or box, for recovery. This box, open at its lower part for the evacuation of the recovered liquid, has a lateral opening through which the liquid jet coaxial with the product penetrates and, in alignment with this opening, a lateral orifice sized so as to allow the free passage of the product while scrolling while obstructing the liquid jet which envelops it. This solution, advantageous by its simplicity, however has drawbacks, in particular as regards the seal of the box at the level of the orifice for the passage of the product. In fact, this orifice cannot be made as close as desired to the diameter of the product to be cooled, so that the annular slot, necessarily present between the two, constitutes for the jet a preferred escape route, thus penalizing, and in a very sensitive way, the function of interruption of the jet which one wished to attribute to such a box. It has also been proposed, for example in French patents 2226221, American patents 1,874,959 and German 2,556,383, to improve the efficiency of such separators and in particular to minimize the quantities of water entrained outside, by applying to the jet surrounding the product a shearing effect using a secondary jet making an angle with the main jet. However, this shearing effect is not always sufficient to prevent any exit of water from the separator, in particular in the case of main jets having a large amount of movement.

A separator has also been proposed (FR.A. 2 261 816) combining means for shearing the jet at the outlet of the cooling tube with means for prior weakening of the jet by deflecting part of it. the outlet end of the tube.

For this purpose, the cooling tube is extended by an open cpude which ensures the deflection of the liquid vein while leaving free passage to the product. This bend is itself extended by a second bend of reverse curvature, the end of which is directed perpendicular to the product in movement so as to shear the residual part of the jet accompanying the product by the part deflected by means of the first bend. It is also planned to enclose all of the elbows in a box to collect and evacuate the liquid thus collected.

Despite the undeniable progress it brings compared to the simple box mentioned at the start, we can blame a separator of this type for the fact that the weakening means act on the liquid stream confined in the cooling tube. It is indeed feared that the pressure drops and the turbulence which inevitably result therefrom lead to a disturbance in the flow of the liquid stream in the invisible tube to the efficiency and good control of the cooling itself.

Furthermore, it is regrettable that, for the same reason, such a separator is hardly compatible with a multiplication of means of weakening the jet arranged successively one after the other, so as to ensure in all circumstances a extensive separation between the moving product and the surrounding liquid envelope.

This handicap can a priori become a serious drawback, for example in the case of the cooling of wires to bars of special steels for which the drying requirements can prove to be very critical for metallurgical reasons.

The object of the present invention is to provide a separator designed so as to be able to effectively interrupt the liquid jet at the outlet of the cooling tube while ensuring the free passage of the product while scrolling and avoiding the drawbacks of known solutions.

To this end, the subject of the invention is a device for separating a long product in movement from a liquid jet which envelops it, constituted by a box having a lateral opening. line through which the product and the surrounding jet penetrate, a lateral orifice in alignment with said opening to allow free passage to the product and a lower outlet for the evacuation of the recovered liquid, the box internally comprising means for weakening the liquid jet surrounding the moving product having an axial recess for the free passage of the moving product and achieving a reduction in the thickness of the jet surrounding the product and means for causing shearing of said jet, device characterized in that the means to weaken the jet consist of at least one element, placed at a distance from the lateral opening through which the product and the jet surrounding it enter the box, and in that the box presents externally in the immediate vicinity of the orifice passage of the product, means for additional drying of the moving product constituted by a blowing member directing the product at least u n gas jet.

By weakening of the liquid jet, we mean qualifying a decrease in its momentum, which, according to the invention operates by reducing the thickness of the jet. This reduction can be carried out by any suitable means, such as a member laminating the jet, while preserving the free passage of the product. It is possible, for example, to use a nozzle, a nozzle, etc. or a simple frustoconical ferrule converging in the direction of propagation of the jet and in the axis of which the product freely passes, but the cross section of which passes narrower of course has a diameter smaller than that of the jet. Furthermore, this reduction means being, in accordance with an essential characteristic of the invention, placed at a distance from the outlet end of the cooling tube, acts on a free jet (and no longer confined in the tube) so that 'It cannot significantly disturb the hydrodynamic characteristics of the flow upstream of the separator.

This reduction in thickness can also be achieved, in accordance with another variant of the invention, by deflection of an annular peripheral layer of the liquid jet, therefore without causing a rolling of the jet. The decrease in the amount of movement is achieved in this case only by a decrease in the flow rate of the jet. A peripheral deflection of this type can be obtained by a deflector constituted, for example as before, by a frustoconical ferrule placed on the passage of the product in movement but whose convergence is, this time, oriented in a direction opposite to that of the propagation jet. It goes without saying that the small open base of the deflector necessarily has a section smaller than that of the liquid jet, the difference between the two determining the thickness of the deflected annular layer.

• - à briser le jet entourant le produit par cisaillement, lequel s'opère de préférence au moyen d'un jet liquide secondaire perpendiculaire au jet entourant le produit,
• - à placer sur le parcours libre du jet après sa sortie du tube de refroidissement, et, de préférence préalablement à l'action de cisaillement, un ou plusieurs organes successifs ayant pour fonction de réduire l'épaisseur du jet,
• - à enfermer le tout dans un caisson servant à la collecte et à l'évacuation du liquide ainsi récupéré,
• - et enfin à parfaire le séchage du produit à la sortie du caisson par des moyens de soufflage dirigeant sur le produit au moins un jet gazeux, par exemple de l'air.

As will no doubt already be understood, the invention consists, in its main characteristics:

• - breaking the jet surrounding the product by shearing, which preferably takes place by means of a secondary liquid jet perpendicular to the jet surrounding the product,
• - to be placed on the free path of the jet after it leaves the cooling tube, and, preferably before the shearing action, one or more successive members whose function is to reduce the thickness of the jet,
• - enclose everything in a box used for collecting and removing the liquid thus recovered,
• - And finally to perfect the drying of the product at the outlet of the box by blowing means directing on the product at least one gaseous jet, for example air.

• - la figure 1 est une vue schématique en coupe axiale d'un dispositif pour le refroidissement de barres métalliques en défilement équipé d'un sépérateur terminal conforme à l'invention,
• - les figures 2, 3 et 4 représentent chacune, en coupe axiale, une variante de réalisation du séparateur conforme à l'invention,
• - les figures 5 et 6 illustrent schématiquement le mode d'action des moyens selon l'invention pour affaiblir le jet principal.

The invention will be clearly understood and other aspects and advantages will emerge more clearly in the light of the description which follows, given with reference to the accompanying drawing plates in which:

• FIG. 1 is a schematic view in axial section of a device for cooling running metal bars equipped with a terminal separator according to the invention,
• FIGS. 2, 3 and 4 each represent, in axial section, an alternative embodiment of the separator according to the invention,
• - Figures 5 and 6 schematically illustrate the mode of action of the means according to the invention to weaken the main jet.

In all the figures, the same elements are designated by identical references.

• - un tube allongé 1 parcouru, dans le sens indiqué par les flèches, par un courant 2 de liquide de refroidissement que l'on supposera être de l'eau,
• - une tête d'alimentation 3 disposée à une extrémité du tube 1 recevant l'eau par une tubulaire d'entrée 4 et l'injectant dans le tube et,
• - à l'autre extrémité, un séparateur 5 recevant le jet d'eau à la sortie du tube par une ouverture latérale 6 et destiné à interrompre ce jet, à recueillir l'eau ainsi récupérée et à l'évacuer par le bas par une sortie 7.

As shown in Figure 1, the cooling device includes:

• - an elongated tube 1 traversed, in the direction indicated by the arrows, by a stream 2 of coolant which will be assumed to be water,
• a supply head 3 disposed at one end of the tube 1 receiving the water through an inlet tubular 4 and injecting it into the tube and,
• - At the other end, a separator 5 receiving the water jet at the outlet of the tube through a lateral opening 6 and intended to interrupt this jet, to collect the water thus recovered and to evacuate it from below by a exit 7.

The cooling bar 8 crosses the device right through and in a rectilinear direction passing along the axis 11 of the tube 1. Openings 9 and 10 formed respectively in the feed head 3 and in the separator 5 allow free passage of the bar 8. It will be recalled that the orifice 10 of the separator is produced in alignment with the tube 1, this in order to ensure the crossing of the bar 8 in a straight line. The opening 6 and the orifice 9 are therefore coaxial and their axis merges with that of the tube designated at 11. It is also recalled that the cooling of the bar takes place essentially during its passage through the tube 1 by direct contact with the water jacket 2 which envelops it and which circulates at high speed.

A sign in this regard that bar 8 and the cooling jacket 2 can flow, either "co-current", that is to say in the same direction, or "against the current", that is to say in opposite directions. Also, in the figure the arrowed indication of the displacement of the bar 8 only underlines the fact that the latter is not stationary but in movement without it being possible to prejudge the real direction of displacement.

According to the invention, the separator 5 consists of a box inside which a secondary jet 12 breaks the main jet by shearing effect. To this end, the secondary jet 12 leaves a nozzle 13 perpendicular to the axis 11, that is to say to the main jet (not shown) surrounding the bar 8.

This secondary jet 12 can be gaseous, or preferably liquid, for example water. In this case, the nozzle 13 can advantageously consist of the outlet end of a conduit mounted as a bypass on the supply of cooling water serving the supply head 3.

The position of the nozzle 13 around the axis 11 1 does not matter. The figure shows it implanted through the upper part of the box 5 so that the shear jet 12 is oriented vertically, thus benefiting to the maximum from the effect of gravity, but it could just as easily have been implanted at through lateral partitions situated in the planes parallel to the plane of the figure.

When the main jet has a large amount of movement, as is the case for the heat treatment of long products at the end of rolling, the power of the secondary jet, necessary to obtain an effective shearing effect, could be such as it would be to fear, first certain difficulties in guiding the product, by deflection of the head at the time of its introduction into the separator, then a bending of the product (in particular for the products of small diameter) at the point d impact of the jet. It is therefore desirable to be able to operate with a secondary jet of moderate impulse, which involves acting on a previously weakened main jet.

This weakening is achieved, in accordance with the invention, by means reducing the thickness of the jet and acting on a jet in the free state, that is to say after it leaves the cooling tube 1 so as not to disrupt the flow inside the latter and to be able, if necessary, to multiply the number of these means on the course of the jet. These means have not been shown in Figure 1 so as not to overload it unnecessarily.

A priori, it is correct to think that, the more the number of successive weakening means, the better the final result obtained.

In fact, as a general rule, a succession of two weakening means suffices to soften the jet so that, after shearing, almost all of the water is recovered in the separator.

Furthermore, the residual water which still beads on the product at the outlet of the box is eliminated by additional drying means 23 with gas blowing which will be described in more detail below.

The following figures illustrate several alternative embodiments of a separator according to the invention and comprising two prior weakening members of the main jet.

In FIGS. 2, 3 and 4, the main jet has not been shown so as not to overload them unnecessarily. As can be seen, the means of prior weakening of the main jet can be simple ferrules 14, of frustoconical shape and surrounding the product 8. These ferrules can be maintained by any appropriate support structure, such as clamps, etc. ... In the examples described, the support structures consist of partitions 15, arranged perpendicular to the axis of the openings 6 and 10. These partitions are fixed to the upper face of the box 5 and left free at their lower end . They have an orifice 16 for the passage of the product 8 and the ferrules 14 are attached to the edges of these orifices.

This produces a box 5 partitioned into several successive compartments, aligned along the moving product and each recovering a fraction of the water constituting the main jet which leaves the tube 1 and whose evacuation is ensured by the outlet funnel 7.

In principle, the relative positions between the ferrules 14 and the nozzle 13 can be reversed. However, the results are all the better (absence of water projection through the orifice 10) that, for a given number of successive ferrules 14, the number of ferrules interposed between the outlet of the tube and the shear jet is large .

Thus, in the case of a box with three compartments (therefore with two successive ferrules 14) as shown in the figures, the nozzle 13 located in the compartment furthest from the tube gives better results than if it were placed in the middle compartment and, in this case, even better than if it were located in the first compartment into which the tube 1 opens.

In addition, a number of successive rings equal to or close to two is suitable in the majority of cases. Under these conditions, the main jet is entirely interrupted in the box 5. Below this number, the quantity of residual water gushing through the orifice 10 may be large enough so that the means of additional gas drying no longer manage to dry suitably the product. Beyond the aforementioned number, the means of weakening the jet often become overabundant and penalize the cooling device due to the unnecessary increase in length which results therefrom.

We will now describe some possible arrangements of these means of prior weakening of the main jet and their mode of action on the latter.

A first arrangement consists, as shown in FIG. 2, of placing the frustoconical ferrules 14 so as to make them converge in the direction of propagation of the jet. We can then indifferently, either bring them by their small base on the face of the partitions 15 touned towards the tube (box in the figure), or bring them by their large base on the opposite face of the partitions 15. Whatever solution is chosen , these ferrules, whose small base has a diameter less than that of the jet, play the role of a foreign exchange loss member by laminating the main jet which passes through them axially. This alternative embodiment appears to be well suited to a circulation of the product in movement and of the cooling water in "co-current", since the ferrules then constitute, with respect to the product in movement, an introduction cone which facilitates guiding of the head of the product as it passes through the box.

Furthermore, such an arrangement has another advantage: as shown in the enlarged view of FIG. 5, the shell 14 fulfills, with respect to the jet (referenced 17), an additional function of reflection by causing the cusp of a part 18 of the water of the main jet, a large fraction 19 of this turned back part then falling back on the jet upstream of the shell. This "folded" portion 19 disturbs the jet before rolling and thus contributes favorably to its weakening. It is easy to understand that the ferrule 14 fulfills its role of reflector only if its large base through which the jet 17 has a diameter greater than that of the jet.

A second possible arrangement is illustrated in FIG. 3. This variant embodiment is characterized by an arrangement of the frustoconical ferrules 14 so as to make them divergent in the direction of propagation of the main jet. This time, the reduction in thickness of the latter, is no longer done by rolling and reflection as in the previous variant but, as clearly shown in the enlarged view of Figure 6, by deflection of a peripheral annular layer 20; this deflection role is of course filled by the ferrule 14 which has a small base with a diameter smaller than that of the jet and whose beveled end 21 acts in a way, like an annular knife which "peels" the jet on its outskirts. The peripheral annular layer 20 thus cut is then deflected by passing over the external face of the shell. For the reasons mentioned above, it is understood that such an alternative embodiment is, this time, better suited to a product-water circulation of the "counter-current" type.

Another possible arrangement is shown in FIG. 4. This variant of readjustment, which can be described as "universal", since it accommodates both "co-current" and "circulation" circulation. against the current ", is characterized by the fact that the means of weakening the main jet are produced by means of two coaxial ferrules 14 assembled by their small base.

It should be noted that, whatever the variant implemented, there is a significantly improved and more regular operation of the separator 5, when an opening is made in it, in the vicinity of the end of the nozzle 13 It therefore appears beneficial to arrange, in the vicinity of the shear jet, an air intake which has been represented at 22 in the figures.

It should be understood that, despite an effective interruption of the main jet in the box, a slight leakage rate generally escapes through the passage opening 10. This leakage rate is moreover inevitable in the case of circulation "co-current" because the moving product then carries with it residual moisture in the form of a thin liquid film or, at best, droplets which remain attached to the surface. Taking into account the surface temperature of the product after cooling (of the order of 200 ° C), this residual humidity is eliminated naturally after a few seconds. However, due to the high speeds of movement of the product, the humidity accompanies the latter over a fairly appreciable distance and one may wish to eliminate it as soon as it leaves the box.

This is achieved, according to the invention, by externally equipping the box with additional drying means by gas blowing.

The blowing jet can be single or multiple, for example a plurality of radial gas jets which converge at the same point of the product at the outlet of the box and which form a gas disc around the product. This gaseous disc eliminates the residual moisture by mechanical effect due to the blowing itself associated with a thermal effect, in particular if the gas is to be preheated. The latter can be of any kind. For obvious reasons of convenience, air should preferably be used. As can be seen in the figures, these additional drying means may consist of a simple circular pipe 23 surrounding the product to be dried 8 and arranged outside the box 5 in the immediate vicinity of the passage orifice 10. The pipe 23 is secured to the box by means of fixing flanges 24. This pipe is supplied by the pipe 25 with pressurized air from a source not shown and the blowing on the product 8 is carried out by means of a plurality of outlet nozzles radials 26 directed perpendicular to the axis 11, so as to create around the product, the air disc previously mentioned.

Of course, the present invention cannot be limited to the examples described, both in that concerns the production of shearing means, weakening of the jet or additional drying of the product than the field of application of the separator.

Thus, the means of weakening the jet can be produced differently insofar as they act on a free jet, that is to say where they are placed at a distance from the end of the tube through which the jet exits and in since they are constituted by a body having an axial recess allowing the free passage of the product while scrolling. In the case of the reflector variant (FIGS. 2 and 5), it is only important that this recess has an internal profile converging in the direction of propagation of the jet and that its inlet end has a diameter greater than that of the jet, then that, in the case of the deflector variant (FIGS. 3 and 6), the condition to be respected resides in the divergent form, in the direction of propagation of the jet, of the external profile of the means used.

Finally, in the case of the so-called "universal" variant (FIG. 4), it is easily understood that the only necessary characteristic of these weakening means consists in assigning them an internal profile of convergent-divergent shape.

In addition, other variants can be used to produce the gas blast drying means. Indeed, it is not essential that the blowing takes place perpendicular to the product. One can thus modify at will the inclination of the nozzles 26, for example so as to direct the gaseous jets onto the passage orifice 10 of the box. The blowing thus causes a gas barrier which thwarts, at the source, the leakage rate of the main jet. Conversely, the nozzles 26 can be oriented in a direction opposite to the previous one, which has the effect of forming around the product to be dried a gaseous sleeve which promotes, by convection, the elimination of residual moisture. Of course, the annular pipe 23 can be equipped with several series of nozzles of different inclinations, in order to simultaneously implement the drying mechanisms mentioned above.

Furthermore, the separator according to the invention applies not only to cooling long products at the end of rolling, but to any other industrial field, in which it is advantageous to quickly remove a liquid film from the surface of a scrolling product. This is particularly the case in continuous casting of metals, for example steel, where the cooling of the casting bar in the so-called "secondary cooling" stage of the installation can be carried out by a ducted water jacket in a sleeve surrounding the bar and circulating in contact with the surface of the latter.

Claims (3)

1. A device for separating a lengthwise product (8) moving past the liquid jet encompassing it, and consisting of an enclosure (5) provided with a side opening (6) through which the product is introduced and the jet encompassing it; a side port (10) in alignment with said opening to let the product flow freely through it and an outlet (7) at the bottom to drain off the recovered liquid; the enclosure comprising inside means to weaken the liquid jet encompassing the product moving past the latter, and also an axial passage through which the product moving past flows freely and which decreases the thickness of the jet encompassing the product, and means (12, 13) to shear the jet, device characterised in that the means to weaken the liquid jet encompassing the product moving past the jet of liquid consist at least of one element (14) located some distance from the lateral opening (10) and in that the enclosure (5) is provided externally adjacently to the side opening (10) with supplementary means for drying the product moving past the liquid jet, consisting of a blower (23), levelling at least one gaseous jet at the product.

2. A device, according to claim 1, characterised in that the external configuration of the element (14), reducing the jet thickness, diverges in the direction in which the jet is propagated and that the end of its axial passage, through which the jet is introduced, is of smaller diameter than the said jet.

3. A device, according to claim 1, characterised in that the enclosure (5) comprises a vent (22) adjacently to the shearing means (12,13).

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