LU100329B1 - Galvanized wire cooling device - Google Patents

Abstract

A cooling system for a wire coating installation comprises: a power supply (12) with a chamber (14) for a coolant and a plurality of fluid outlets (16); and a plurality of projection heads (18) each provided with one or more coolant spray openings (20) to a wire to be cooled (11), each projection head being connected to a fluid outlet (16) respective for supplying fluid to an internal passage (54) of the projection head (18) extending to the or orifices projection. A service valve (22) associated with each projection head (18) for selectively controlling the fluid supply of the inner passage (54) of the projection head. A bleed means (30) is associated with each throwing head (18), the triggering of which permits the evacuation of fluid from the internal passage (54), in order to stop the projection of fluid through the orifices of projection (20).

Description

The invention relates to the field of wire coating, more particularly to the coating of dipped wires, such as, for example, the galvanizing of metal wires. Even more particularly, the invention relates to a device for cooling coated wires, in particular coated metal wires coming out of a continuous hot-dip galvanizing bath, or more generally from an anti-corrosion bath.

Continuous hot-dip galvanizing of wire typically involves dipping a wire into a molten metal bath (zinc alloy); controlling the charge of the metal coating on the running wire by means of a gas wiping system at the outlet of the galvanizing bath; and finally to cool the wire to an acceptable temperature before contact between the galvanizing coating and the driving parts of the wire running. It is well known to those skilled in the art to cool a wire moving by projection of water, gas, or a water / gas mixture. In a line of continuous galvanization of metal son, several son move in parallel with each other; and it is known for post-galvanizing cooling to use cooling devices forming a water jet oriented on each of the son to be cooled.

Each jet of water is conventionally formed by a nozzle directed towards a running wire and connected to a water supply pipe. The nozzle is generally directed toward the yarn in a direction at a substantially acute angle with the direction of travel of the yarn so that the water jet, at the top of its path, comes into wire contact before falling back into a tray back of the wire.

In case of metal wire size change or scheduled maintenance activities, it is necessary to stop the water supply of all nozzle devices to stop the water jets. During this operation, the drop of water drops in the galvanizing bath should be avoided because this may cause splashing of molten metal, which can cause very heavy injury to the operator in action around the equipment or any nobody nearby. This risk is even more critical in the event of a failure of the galvanizing installation requiring an emergency stop.

US Pat. No. 3,743,535 describes, for example, a device for cooling water jet wires for a galvanizing installation. The invention aims to overcome the disadvantages of the state of the art, in particular the state of the art mentioned above. More particularly, the invention aims to provide a cooling system whose implementation is simple, and which allows a rapid stop of the projection of water to the son for better operator safety.

With this object in mind, the present invention provides a cooling system for a running wire coating installation, which comprises: a power supply unit with a chamber for a coolant and a plurality of fluid outlets; a plurality of projection heads each provided with one or more cooling fluid projection orifices to a wire to be cooled, each projection head being connected to a respective fluid outlet so as to supply fluid to an internal passage of the head projection extending to the projection orifice (s); a service valve associated with each projection head so as to selectively control the fluid supply of the internal passage of the projection head; a purge means associated with each projection head, the triggering of which allows the evacuation of fluid from the internal passage, with a view to stopping the projection of fluid through the orifices of projection.

In the invention, the purge means is therefore designed to cause a pressure drop, preferably almost instantaneous, in the internal fluid passage of the spray head, by fluid evacuation. This purge means, which will act downstream of the service valve, allows to evacuate the cooling fluid to a position closer to the projection orifices, which results in an immediate stop of the projection of water.

It should be noted that the effects are immediate and in this sense innovative compared to the state of the art: more risks of water spray on the surface of the molten galvanizing bath. As a reminder, the major risks consist in trapping a drop of liquid, especially water, in the molten metal bath (most often between 400 and 750 ° C depending on the metal coatings or between 50 and 300 ° C for organic coatings or polymers). The water vaporization energy of the drop of water is accompanied by a strong volumetric expansion, and projects the liquid metal to several meters generating very high risk of burns that can even be fatal for a nearby operator. Activation (triggering) of the purge means in the system of the invention therefore makes it possible suddenly to stop the projection of water and prevent such droplets from falling into the bath of molten metal.

The purge means of the present system is particularly useful for instant shutdown of the cooling system, and will also be called emergency purge means. But as will be seen, the purge means can also be used for a planned maintenance stop or for any routine operation.

Preferably, the purge means is of the vacuum type, which allows forced evacuation of the cooling fluid from the internal passage of the projection head. Thus, the emergency purge means advantageously comprises a cooling fluid suction means. In particular, it will be possible to use a vacuum chamber coupled to a vacuum pump.

According to one variant, the emergency purge means comprises, for each head, a purge line connecting the control head (in particular a purge orifice), via a purge solenoid valve, to the suction means (for example the vacuum chamber). ).

For even greater efficiency, the activation of the emergency purge means is advantageously coupled to the closure of the service valve. That is, the cooling system control module is designed so that when an emergency stop of a given projection head is desired, activation of the emergency drain means ( opening of the purge solenoid valve) is performed substantially concomitantly with the closing of the service valve.

According to the variants, the system comprises one or more of the following technical characteristics: the internal passage of the projection heads comprises a feed prechamber with a purge orifice cooperating with the purge means, and projection ducts opening onto the orifices projection, the entrances of the projection pipes from the prechamber supply; the projection duct or ducts have a continuous section between their entry and their exit; the internal passage of the projection heads defines a casing forming the lower part of the pre-chamber of supply, the purge orifice being made at the level of said casing; - The internal passage of the projection heads further comprises a fluid reserve chamber followed by a restricted passage downstream of said chamber, said restricted passage being followed by the prechamber supply; - The section of the reserve chamber is reduced with the approach of the restricted passage to the prechamber supply; a valve, preferably of the diaphragm type, is provided for individually adjusting the flow rate of each projection pipe; each of the projection heads is removably mounted on the power supply unit, preferably via a connection piece fixed by a first mechanical coupling sealed to the block and by a second mechanical coupling sealed to the projection head, the connecting piece comprising an internal passage for conveying the fluid from the outlet to the internal passage of the projection head; - The service valve associated with each projection head is mounted on the connecting piece and allows to seal or release the passage through the internal passage. Other features and characteristics of the invention will become apparent from the detailed description of at least one advantageous embodiment presented below, by way of illustration, with reference to the accompanying drawings. These show:

Figure 1: A) a view from above and B) a side view of an embodiment of a cooling system for a wire coating installation according to the invention (in view 1B the power supply unit is truncated);

Figure 2: sectional view of the cooling system of Figure 1A at a projection head (section A-A);

Figures 3 and 4: schematic views of two alternative embodiments.

Figure 1 shows a cooling system 10 for a galvanizing installation of metal son. The installation is not shown, however, we can see a series of son 11 arranged next to each other and extending vertically. In the case of a galvanizing installation, the cooling system 10 is placed above the galvanizing bath, and the outgoing son 11 of the bath scroll vertically, side by side. At the outlet of the bath, the son coated with a layer of anticorrosive coating, partially solidified, are first wiped by a jet of gas (most often in air or a mixture air-gas neutral), then are cooled by jets of water as mentioned in connection with the description of the prior art. The present cooling system 10 will therefore be advantageously used to produce such jets of water.

The cooling system 10 comprises a supply unit 12 with an internal chamber 14 for a cooling fluid; the power supply 12 is also called collector. The power supply 12 has an elongated tube shape, e.g. cylindrical - here of square section (but may also be circular or other), closed at one end and comprises an inlet 15 at an opposite end for connecting the block to a power source (not shown). The power source can typically be the water network of the production line. It is advantageously a network in closed circuit, thus forming a recirculation loop. The inlet passage 15 is surrounded by a connecting flange 15.1. As best seen in Fig.1 B, the power supply 12 has on one side face of fluid outlets 16. The side face is located between the two ends of the block. The power supply 12 thus forms a distributor unit or water supply manifold.

The cooling system 10 comprises projection heads, generally indicated 18, each of which is connected to one of the fluid outlets 16, preferably in a removable manner. As presented in connection with the description of the prior art, the son 11 out of a corrosion-resistant metal alloy bath and scroll vertically for drying and cooling.

The power supply 12 typically extends perpendicularly to the direction of travel of the wires so that the projection heads 18 are located in the axis of the wire 11 traveling.

Each of the projection heads 18 comprises one or more orifices 20 for spraying coolant (here three orifices 20 - FIG. The fluid leaving each of the heads 18 via the projection orifices 20 is projected onto the corresponding wire 11.

FIG. 1 shows a power supply unit 12 with more than twenty fluid outlets 16, each of which is connected to a respective projection head 18. In an alternative embodiment, the power supply 12 may comprise more than thirty or even more than one hundred outputs in very large galvanizing plants.

The fluid projected on the son is not shown in Figure 1, however the power supply 12 is in practice arranged horizontally in front of the son 11 which scroll vertically. The projection heads 18, whose configuration is described in detail with reference to FIG. 2, are made so that the fluid is projected upwards, in the direction of travel of the wires, the jet of fluid at the start of the orifices 20 forming a suitable angle, for example between 10 and 80 °, preferably between 30 and 60 ° with the horizontal. The fluid jets are shown schematically in FIG.

The speed of the fluid from the orifices 20 is predetermined so that the fluid, at its maximum altitude, comes into contact with the wire to cool it homogeneously over its entire circumference / periphery with the maximum thermal efficiency. . The shape of the jet is advantageously controlled by the flow rates and preferably by diaphragm valves (noted 74), thus allowing the control of the thermal rendering at the periphery and in the longitudinal direction of the wire. The fluid then falls to the end of the stroke in a recovery tank (shown symbolically 27 in Fig. 1A), generally located between the anticorrosive coating bath and the cooling system. The cooling fluid may be water or another type of medium such as a mixture of water / air, water / gas, insulated fluid, an alcoholic fluid, or a liquid gas. Those skilled in the art can design the projection head 18 so as to obtain the desired jet parameters. In general, it is designed so that the vertices of the water jets (at the tangent) impact the wire to respect the principles of fluid mechanics according to which, it is possible at this tangent, that the jet of water dissociates perfectly and completely "surrounds" the wire in its circumference, which generates a very good cooling around the section of the wire. At these tangents, the turbulence of the jets are almost zero, and therefore the thermal transfers between the wire and the fluid are optimum, which allows a perfect control of the cooling rate.

As will be seen better in FIG. 2, the cooling system 10 comprises, for each of the projection heads 18, a service valve 22 so as to open or close the fluid supply of said projection head 18; and this selectively depending on whether the head is to be put into operation or not. In the event of malfunction or maintenance of a projection head 18 or of the wire running system 11, then the service valve 22 can be closed in order to stop the supply of water to the head 18. In the event of a defect of the projection head 18, it can be disassembled and replaced, or repaired. The service valve can also simply cut off the supply of the head 18 if one wants to intervene in the rest of the installation, or if there is no wire in front of the head.

It will be appreciated that the cooling system 10 includes bleed means 30 which is associated with each of the throwing heads 18. It is preferably a vacuum bleed means. The purge means 30 is designed so that its release allows the evacuation of fluid from the projection head 18, in order to stop the projection of fluid at the projection orifices 20. It is preferably designed to empty the the entire volume of fluid contained in the head.

Preferably, the system 10 is designed so that the triggering of the bleed means 30 of a throwing head 18 is coupled to the closing of the service valve 22 of the throwing head 18 in question.

The purge means 30 allows an immediate stop of the projection of water, if necessary. It is thus also called emergency purge means.

In normal operation, the fluid supply pressure of the projection head 18 is generally between 1 and 2 bar (absolute), for example of the order of 1.2 bar for use in gravity mode. Use in pressurized mode for example for the projection of fine water droplets, on air bed, fine fog type, could cause pressures up to about 10 bar. For the adjustment of the pressure of the cooling fluid, a compressor (not shown) is preferably associated with the manifold 12. This compressor also be part of the water supply circuit of the production line.

In the event of an emergency stop, the triggering of the bleed means 30 of a throwing head 18 generates a sudden drop in the pressure of the fluid in the throwing head 18 so that the fluid ejection pressure at the corresponding ejection ports also drops suddenly. The immediate effect is to stop the projection of fluid on the wire; it is also the one not to generate drops of fluid during this emergency stop. The purge means 30 allows the instantaneous stopping of the flow of cooling fluid leaving the projection heads 18. As mentioned, the introduction of the depression by the purge means is preferably carried out substantially concomitantly with the closing of the valve. service 22.

As indicated, for greater efficiency, the purge means 30 is preferably of the vacuum (or suction) type, that is to say that it allows forced suction of cooling fluid out of the spray head . In the illustrated variant, the purge means 30 comprises a vacuum chamber 32, purge valves and a purge line network, cooperating with a purge port 60 communicating with the internal fluid passage of the head 18. Each of the Pipes of the pipe network connects the vacuum chamber 32 to a respective spraying head 18, via a dedicated purge valve. The purge line network and the purge valves are not shown in detail in FIG. 1.

In more detail, FIG. 2 is a sectional view of the cooling system 10, at one of the projection heads 18. It is possible to see the power supply unit 12, the vacuum chamber 32, one of the purge lines 34 connecting the vacuum chamber 32 to the projection head 18 via one of the purge valves 36 (solenoid valve). In practice, to serve all the projection heads, one can have a common bleed pipe 34 connected to the vacuum chamber 32 and passing under all the projection heads 18, from which are pitted lines 34.1 individual carrying purge valve 36, as suggested in Fig.2. To the right of Figure 2, there is shown a wire 11 coated with a corrosion-resistant alloy layer (not shown) and an upward-pointing upward arrow indicating the direction of travel of the wire 11.

The reference sign 40 designates a connecting piece associated with the projection head 18; the connecting piece 40 comprises a body 40.1 with a first mechanical coupling 42 to the power supply unit 12.

A second mechanical coupling 52 is provided to allow mounting of the projection head 18 on the body 40.1.

The projection head 18 comprises an internal passage 54 for the cooling fluid, which flows from the manifold 12 through the connecting piece 40.

The internal passage 54 extends from the second coupling 52 through the projection head 50 to terminate at the projection ports 20.

The first mechanical coupling 42 of the connecting piece 40 is made at the level of the fluid outlet 16 of the supply block 12, which allows a hydraulic connection between the chamber 14 of the supply block 12 and an internal passage 40.2 in the body 40.1. The fluid outlet 16 has for example a form of connector which is designed to cooperate with the first mechanical coupling 42, so as to ensure both the attachment of the head 18 to the power supply 12 that the transfer of fluid. The internal passage 40.2 opens at the second mechanical coupling 52, to feed the internal passage 54 of the projection head.

The first and second mechanical couplings 42 and 52 are fluid-tight couplings; these couplings can be of any suitable type, for example a conventional quick coupling, or, if working under pressure, a clipping and / or bolting connection (double fastening if necessary). The skilled person may consider various embodiments for these sealed couplings. The hydraulic connection between the chamber 14 of the power supply unit and the internal passage 54, via the connecting piece 40, is therefore a sealed hydraulic connection.

The service valve 22 associated with the projection head is formed as a pneumatic shutter 22 mounted on the body 40.1. The pneumatic shutter 22 comprises an actuator mounted with a movable piston 23 ending in a closure member which, in the retracted position shown, leaves open the internal passage 40.2 for the fluid in the body 40.1; that is to say that the cooling fluid can flow from the manifold 12 to the projection head 18. In the output position of the movable piston 23 (in dotted lines), the closure member bears on a sealing seat 25 surrounding the internal passage 40.2 in the body 40.1, and thereby closes the internal passage 40.2. In the closed configuration, water does not flow from the power supply 12 to the projection head 18.

Preferably, the internal passage 54 of the projection head 18 comprises a feed pre-chamber 56 and projection lines 58, 58 'and 58 ". In Fig.2, the prechamber 56 is not visible because it is in a plane behind that of the figure. The supply pre-chamber 56 comprises a purge port 60 (in dashed line) to which the purge means 30 is connected. The entries 62, 62 'and 62 "of each of the projection lines 58, 58' and 58" start from the pre-chamber 56. The projection pipes 58, 58 'and 58 "terminate a projection orifice 20.

In particular, the internal passage 54 of the projection head 18 defines a casing 64 forming the lower part of the feed pre-chamber 56 and the bleed orifice 60 is formed at this casing 64.

Each of the purge lines 34 and the purge solenoid valves 36 are dedicated to a respective projection head 18. The purge line 34, starting from the vacuum chamber 32, is connected to the purge orifice 60 made at the level of the casing 64 situated in the lower part of the feed pre-chamber 56.

The triggering of the emergency venting means 30 may be performed for one or more cooling heads 18, according to the planned intervention.

In the event of an incident, it can support a single wire and then the purge means is triggered for a single projection head 18. In the course of a maintenance operation, the triggering of the purge can be operated for several purge heads.

In this context, the system advantageously comprises a control module 80 which is designed to control the actuation (opening / closing) of the service valves 22 and the purge valves 36, and preferably the flow control diaphragms 74 to The control module 80 also monitors the pressure in the chamber 14 of the power supply 12, and the vacuum in the vacuum chamber 32, which is preferably in use during the operation of the cooling system 10. The control of the service valves 22 is done independently; each of the service valves can be individually controlled. The purge valves 36 are also individually controllable so that they can operate on a given head.

It should be noted, however, that for better performance in an emergency, it is preferable that the actuation of a purge valve 36 (ie its opening) is coupled or coordinated with the closing of the valve. corresponding service 22. The control module is therefore advantageously configured so that an emergency purge instruction triggers, substantially concomitantly, the opening of the purge valve and the closing of the service valve associated with the projection head 18. L emergency purge instruction can be given automatically following the detection of an event by a sensor, or by intervention of an operator on a console or an emergency button.

The triggering of the purge means 30 therefore implies the opening of the purge solenoid valve 36 which allows the evacuation of fluid from the internal passage 54 of the projection head 18. The triggering of the purge means connects the chamber hydraulically in the vacuum chamber 32 with the feed pre-chamber 56. The pressure in the vacuum chamber 32 is at a value lower than the atmospheric pressure, which generates a suction of fluid out of the internal passage 54. The pressure in the vacuum chamber can set to a value between 0.5 bar and 0.2 bar.

The supply pre-chamber 56 from which the projection lines 58, 58 'and 58 "depart is primarily emptied of fluid when the purge means 30 is triggered. The projection ducts 58, 58' and 58" are favorably of identical section. , and the corresponding inputs 62, 62 'and 62 "are preferably grouped at the pre-feed chamber 56 to simultaneously suck the fluid in the projection pipe.

The internal passage 54 of the projection head 18 further comprises a reserve chamber 70 at the projection head 50. The feed pre-chamber 56 is hydraulically connected to the reserve chamber 70; the hydraulic connection is made by a passage with a restricted section 72. Seen in the direction of displacement of the fluid in the projection head 50, the feed pre-chamber 56 is located downstream of the reserve chamber 70. The section of the chamber reserve 70 is reduced with the approach of the restricted passage to the pre-feed chamber 56.

In practice, the system is designed to ensure a controlled fluid pressure, considering the pressure losses; in particular, if we note Q1 the flow in the manifold 12, Q2 the flow rate in the reserve chamber 70 and Q3 the flow rate in the pre-feed chamber 56, we have Q1> Q2> Q3.

Note also in Figure 2 the presence of diaphragm valves, shown schematically 74, mounted on each projection pipe. The projection lines may be integral with the body of the projection head 18 or inserts. In the latter case the diaphragm valves may be designed to mount the projection pipes on the projection head. The diaphragm valves can be motorized, which allows their adjustment remotely (via command 80) or alternatively, manual.

Figures 3 and 4 relate to two variants in which two identical systems of power supply units are used with their projection heads and positioned in opposition to the wires. The systems are similar to the one shown above and designated 10.1 and 10.2. Projection of both sides of the wire 11 will improve the homogeneity of the cooling.

In Figure 3, the two cooling systems are positioned at the same height, so that the same pipes produce jets of water 8 arriving at the same height on the wire.

In Figure 4, the cooling system 10 'on the right in the figure is lower than the left one. For example, it is offset by a distance corresponding to the half distance between two jets 8 of the gauchel system 0.1.

The present cooling system 10 is advantageous in many aspects. A) Respect of the quality of the product and improvement of its surface quality: - no thread-type contact, therefore no risk of damaging the coating during solidification; - Control and control of jet speeds along the wire in vertical scrolling (better control of the appearance quality of the product).

As is known, controlling the cooling of the coating layer after the bath is essential in the galvanizing processes. The present cooling system brings even more control of the cooling and solidification parameters, so that the product quality is improved (appearance and also corrosion resistance of any possible nature, withstand the environment and the demands of the environment for organic or polymeric coatings, durability). B) Improvement of the productivity: - The adjustment of the parameters of cooling do not require any more of line stop. They can be done online, in operation while respecting the drastic safety rules. - The flow rate / fluid velocity settings are individualized wire to wire, and facilitate the adaptation of process parameters during changes in product formats (type of wire, diameter of wire, thickness of the coating, speed of scrolling). - The system consists of two separate parts, assembled in a perfectly sealed manner (with water and air). It is therefore possible to disassemble each projection head, according to production needs, independently of each other, without hindering or slowing down the productivity of the wires running around the head 18 to be dismantled (for inspection, cleaning, repair ...) . The projection heads 18 are interchangeable with each other, independently of the production notebook. In addition to an economic gain with the interesting purchase, the gains in maintenance time are considerable (1 only product reference) C) Strong improvement of the security conditions: - The interior design of the projection heads is made so that, coupled with the pneumatic shutter, the jets of water can be instantly cut. This is possible thanks to the vacuum purge means. The effects are immediate and innovative compared to the state of the art: more risks of water projection on the surface of the molten galvanizing bath. D) Strong improvement of consumption of water or cooling fluid: - A strong advantage of the present system is based on the non-use of nozzles as is usually done. So that there is no risk of clogging of the nozzles and thus overconsumption or poor control of water consumption (an overconsumption of water in a closed circuit causes more impurities in the circuit, fouling filters, the need to open the circuit to purge ...). - Moreover, the ability to instantly cut off the water supply, greatly promotes the control of water consumption, just when necessary.

Another advantage of the present invention is its very small size. The present cooling system can easily be installed in existing installations, the free space of which is very constrained, without the need to modify them.

The present system has been described in the context of continuous hot-dip galvanizing (Zn-based bath, Galfan® type, Zinc-Magnesium, or any other corrosion-resistant metal alloy), for rolled and dip-coated steel wires. . This application is a simple illustration. It is clear to those skilled in the art that the present cooling system can be used for the projection of cooling fluid on son, metal or polymer, coated with various coatings, anticorrosion or other purposes, metallic, organic, mineral, or chemical.

Claims (12)

A cooling system for a wire coating installation, the system being characterized by: a power supply (12) with a chamber (14) for a coolant and a plurality of fluid outlets (16); a plurality of projection heads (18) each provided with one or more orifices (20) for projecting the coolant towards a wire to be cooled (11), each projection head being connected to a respective fluid outlet (16) so as to supply fluid to an internal passage (54) of the projection head (18) extending to the projection orifices; a service valve (22) associated with each projection head (18) for selectively controlling the fluid supply of the inner passage (54) of the projection head; a purge means (30) associated with each projection head (18), the triggering of which allows the evacuation of fluid from the internal passage (54), in order to stop the projection of fluid through the orifices of projection (20). 2. Cooling system according to claim 1, characterized in that the purge means comprises a means for suction (30) of cooling fluid, so as to cause a forced suction of cooling fluid from the internal passage. (54) 3. Cooling system according to claim 2, characterized in that the purge means (30) comprises for each projection head (18) a purge pipe (34.1) connecting the projection head, via a purge solenoid valve (36). ), by suction means, in particular a vacuum chamber (32). 4. Cooling system according to claim 2 or 3, characterized in that the internal passage (54) of the projection heads comprises a supply prechamber (56) communicating with a purge port (60) cooperating with the purge means (30), and projection ducts (58, 58 ', 58 ") opening onto the projection ports (20), the inlets of said projection ducts extending from said supply prechamber. 5. Cooling system according to claim 4, characterized in that the or the projection pipes have a continuous section between their inlet and outlet. 6. Cooling system according to claim 4 or 5, characterized in that a valve (74), preferably of diaphragm type, is provided to individually adjust the flow of each projection pipe. 7. Cooling system according to claims 4, 5 or 6 characterized in that the internal passage (54) of the cooling heads defines a casing forming the lower part of the pre-chamber feed, the purge orifice being made at the said collection. 8. Cooling system according to one of claims 4 to 7, characterized in that the internal passage of the cooling heads further comprises a fluid reserve chamber followed by a restricted passage downstream of said chamber, said passage restricted being followed by the pre-feed chamber. 9. Cooling system according to claim 8, characterized in that the section of the reserve chamber is reduced with the approach of the restricted passage to the prechamber supply. 10. Cooling system according to one of claims 1 to 9, characterized in that the activation of the purge means is coupled to the closure of the service valve. 11. Cooling system according to one of claims 1 to 9, characterized in that each of the projection heads (18) is removably mounted on the power supply unit (12), preferably via a connecting piece (40). ) secured by a first sealed mechanical coupling (42) to the block (12) and a second sealed mechanical coupling (52) to the projection head (18), the connecting piece (40) including an internal passage (40.2) for conveying the fluid from the outlet (16) to the internal passage (54) of the projection head (18). 12. Cooling system according to claim 11, characterized in that the service valve (22) associated with each projection head (22) is mounted on the connecting piece (40) and allows to seal or release the passage through the internal passage (40.2).