EP3638821B1 - Nozzle for a hot-dip coating system - Google Patents

Description

Technical Field

The present application describes a so-called "snout" construction as it is typically used in industrial practice as an essential part of a hot-dip or hot-dip coating system. The flat metal product, such as steel, which has previously been heat-treated in continuous flow, is transferred as a strip into a coating bath made of molten metal (e.g. Zn or Al-based alloys) via such a trunk, so that there is contact between the heat-treated surface and the ambient atmosphere is avoided.

Technical Background (Background Art)

For example, a system for the continuous hot-dip coating of steel strip consists, among other things, of a continuous annealing furnace, a molten bath, a device for adjusting the coating thickness and a subsequent cooling device. The steel strip is continuously annealed in the continuous furnace, the continuous furnace being divided into several chambers in which various treatments are carried out. These treatments include, for example, setting the desired mechanical properties of the base material through recrystallization of the steel. In addition, iron oxides formed in a preheating zone are reduced. In a cooling zone following the continuous annealing furnace, the strip is cooled under protective gas (HNX) to a temperature close to the melt bath temperature. The protective gas is intended to prevent the annealed strip from oxidizing before the hot-dip coating, which would considerably impair the adhesion of the zinc layer, for example. Because of the different treatments, different gas atmospheres are sometimes required in the chambers. The connecting piece or lock between the annealing furnace and the molten bath containing protective gas is called a trunk.

Coating faults, the causes of which are to be found in the trunk, represent a significant challenge for every operator of such a hot-dip coating system. It is known that metal evaporates from the liquid melt pool inside the trunk and can be deposited on the steel strip or the inner wall of the trunk, for example. This observation is reinforced when measures are used to generate a directed flow in the melt in the trunk, for example by using zinc pumps. Both can cause qualitative failures of the flat steel product to be produced, for example also due to the falling of condensed and agglomerated metal dust from the inner wall of the trunk onto the flat steel product.

Simple and established countermeasures are e.g. the targeted dewing of the trunk atmosphere to reduce the evaporation rate or the heating of the trunk. However, the former has the negative side effect of increased slag formation on the melt pool surface or coating pool level, which also produces quality losses. Furthermore, heating the trunk does not in itself prevent the presence of the metal dust, so that it can continue to be harmful to the process.

It was recognized that the steel strip moving in the direction of the zinc bath entrains protective gas downwards in the trunk, whereby the entrained protective gas on the surface of the zinc bath absorbs zinc vapor, which condenses or resublimates on the colder inner walls of the trunk and becomes dust there when the entrained protective gas rises settles. The prior art therefore describes a large number of technical solutions for avoiding or removing metal dust in a trunk.

From the DE 10 2012 106 106 A1 an example is known from the field of the trunk of a galvanizing plant. Here, an area with a large number of injection openings lies adjacent to an area with a large number of suction openings, the areas at least partially engaging in a comb-like manner. This achieves a relatively good seal against rising zinc vapors from the gas atmosphere above. However, such a device is relatively expensive to manufacture and requires a lot of space. Due to the high saturation of the gas atmosphere caused by the seal before immersion with zinc vapor, the product quality can also be impaired. In addition, the permanently installed devices must be completely dismantled for maintenance work or the trunk must be removed as a whole.

From the DE 10 2015 108 334 B3 Another example is known from the field of the trunk of a galvanizing plant.

Summary of Invention

The invention is therefore based on the object of providing a device which enables maintenance work, such as cleaning and the like, to be carried out quickly and easily. Further objects of the invention are inexpensive manufacturability, low space requirements and easy assembly enable or is suitable for retrofitting to existing systems and can be implemented with the least possible technical effort.

A secondary task is to prevent adjacent gas atmospheres from being influenced, in particular to achieve a separation of the trunk and furnace atmosphere in order to avoid unnecessary protective gas consumption or contamination of the furnace.

This object is achieved by a trunk according to the features of claim 1.

According to the invention, a trunk for a hot-dip coating system for a flat product, which extends from the exit of a continuous furnace into a melt below the coating bath level and isolates the flat product from the environment, wherein at least one suction unit and one blowing unit are provided, characterized in that the blowing unit and the suction unit are provided on a common carrier plate, that the carrier plate is connected to the trunk along one edge via at least one joint, and that the carrier plate can be moved into a closed position in which the carrier plate closes an opening on the trunk, and into an open position . Due to the arrangement on a common carrier plate, the injection and suction units can simply be moved at the same time and the positioning to one another is retained. Due to the connection with a joint, the carrier plate with the blow-in and suction units can easily be moved into an open position for maintenance work, making it easily accessible. In addition, the joints maintain a defined positioning of the carrier plate and thus the blow-in and suction unit, which is why the closed position is quickly and easily switched back to the closed position after maintenance work and an operational trunk is achieved.

Embodiments of the trunk according to the invention are characterized in that the opening in the trunk is formed by a frame, the frame having a circumferential counterplate which is in contact with the carrier plate in the closed position. A trunk can be easily equipped or retrofitted through the frame, since this stiffen the structure of the trunk and any installation space required for the blow-in and suction unit is made available. Furthermore, by means of the counter plate provided on the frame, a corresponding counter piece can be provided for the carrier plate in order to achieve good support and sealing.

In preferred embodiments of the trunk are characterized in that the frame has a greater length at least in the longitudinal direction of the trunk than the recess in the wall of the trunk so that there is a protrusion of the wall of the trunk within the frame. This configuration makes it easier to connect the frame to the trunk. This also provides a limitation of the wall of the trunk in the frame, which can be used, for example, as a stop or positioning aid for other built-in components, such as sensors and the like.

Particularly preferred embodiments of the trunk are characterized in that the injection unit and suction unit are mounted on a cover plate which is connected to the carrier plate, and that the cover plate overlaps at least in some areas with the protrusion of the wall of the trunk within the frame. In these embodiments, the protrusion of the wall of the trunk within the frame is at least partially used as a support surface for a cover plate. The cover plate carries the parts of the blow-in and suction unit that lie inside the trunk when the unit is closed. A double-walled design is achieved by the cover plate, which improves the thermal insulation and, in particular, the sealing of the trunk from the environment. For this purpose, further sealing elements can be provided on the cover plate and / or the protrusion.

In further particularly preferred embodiments, probes according to the invention are characterized in that an insulating material is arranged between the carrier plate and the cover plate. This insulating material further improves the thermal insulation. In addition, noise pollution can be dampened by any operating noises from the blower and suction unit during operation. Mineral wool in particular can be used as an insulating material.

Further embodiments of the trunk according to the invention are characterized in that closure means for releasable attachment to the trunk or the frame are provided at least along a further edge of the carrier plate. In particular, the edge opposite the joints is suitable for attaching the closure means, but the closure means can also be provided circumferentially over several edges of the carrier plate. By chipping the closure means, the carrier plate is pressed onto the counterplate or the wall of the trunk in order to ensure a good seal and a firm positioning of the blow-in and suction unit.

Trunks according to further embodiments are characterized in that a limiting means is provided on the carrier plate, the trunk, the frame or the joint, by means of which the open position is defined. The limiting means, which are designed as a stop, for example, ensure on the one hand that the open position is defined and that the carrier plate and thus the blow-in and suction unit have a fixed and safe position for maintenance work. On the other hand, the limiting means ensure that lines to and from the blow-in and suction unit are not impaired or that other fittings and additions to the trunk are not damaged by the support plate or lines and the like protruding from this support plate.

Further embodiments of the trunk according to the invention are characterized in that the carrier plate has a circumferential sealing area which, in the closed position, overlaps with the wall of the trunk or the counter plate of the frame. For example, a graphite-copper seal with a circumferential annular groove can be used, the annular groove also preferably being exposed to inert gas such as nitrogen (N ₂ ). This achieves a reliable sealing of the trunk atmosphere from the environment.

Trunks of further embodiments are characterized in that the injection unit and suction unit are each connected to at least one line centered over the width for the supply or discharge of gas, that the lines are led through the carrier plate to the outside and are firmly connected to the carrier plate, and that the lines are each provided with a flange. By passing the lines through the carrier plate and the connection, in particular the circumferential welded connection, with the carrier plate, on the one hand, the sealing of the trunk atmosphere from the environment is ensured. In addition, the fixed connection achieves a defined position of the lines, which facilitates the connection to other units, such as a protective gas source, processing plants and the like.

Preferred embodiments of a trunk according to the invention are characterized in that the lines have an arc on the outside and adjacent arcs are oriented in different directions. A connection of the shielding gas and suction channels, which are preferably of flexible design, is simplified via the flanges. The arches have the advantage of keeping the installation space required at the top small or of allowing the largest possible opening angle for the open position. Another advantage lies in the different orientation of the arches, which creates the different channels do not disturb spatially. The flanges are preferably aligned in a direction parallel to or pointing away from the edge of the carrier plate, which is connected to the trunk by means of at least one joint.

Trunks according to the invention are characterized in further embodiments that the at least one injection unit and one suction unit on both sides of the flat product each extend over the transverse extent of the trunk on opposite walls, that the injection units are provided directly opposite one another, that the injection units each have at least two rows a plurality of slot nozzles with intervening interruptions, the slot nozzles of the rows are arranged offset to one another, and wherein the interruptions are shorter than the slot nozzles of the adjacent row so that the slot nozzles of the rows overlap in the material flow direction, and that the slot nozzles of an injection unit each have one Interruption of the opposite injection unit is opposite. Thus, the injection units lie on both sides of the flat product guided through the trunk, preferably a continuous material web, such as steel strip. Due to the arrangement in rows and the interruptions in the rows, the slot nozzles can be used optimally, since the jet expansion of the protective gas flows emerging from neighboring slot nozzles does not interfere with one another and the arrangement forms a closed gas curtain. Due to the staggered arrangement of the slot nozzles of an injection unit in relation to the slot nozzles or interruptions in the opposite injection unit, a tight gas curtain is also formed in the middle area of the lock where the injected gas streams meet. In this way, a very good separation of the gas atmospheres is also achieved outside the material web.

Further embodiments of the trunk according to the invention are characterized in that the suction units have main openings provided over the transverse extent, the main openings being aligned in the direction of material flow in order to generate a circulating flow. The main openings are thus on the side facing away from the injection unit, which promotes entrainment of the injected gas in the direction of the material flow and the gas atmosphere is circulated. In this way, for example, zinc dust in a proboscis can also be sucked off and then filtered in order to obtain a largely "clean" gas atmosphere.

In preferred embodiments of the trunk, the injection units and suction units are each connected to at least one centered line for supplying and removing gas. In this way, the fluidic conditions can be kept largely the same over the width of the injection and extraction units.

In particularly preferred embodiments of the trunk, the main openings have a greater height in the area of the centered line. Such a design keeps the flow conditions more uniform across the width, which improves the suction effect.

Further versions of the trunk are characterized in that the suction units comprise additional openings which are oriented perpendicular to the direction of material flow. These additional openings improve the pressure conditions in the trunk and reduce the flow velocities at the openings of the suction unit, which has advantages in terms of noise and wear.

In embodiments of the trunk, the slot nozzles are characterized in that the slot nozzles have a width b, that the distance a between the rows is in the range of b ≤ a ≤ 2 * b, and that the overlap u of the slot nozzles in the material flow direction is in the range of b ≤ u ≤ 3 * b, with a ≤ u in addition. In order to achieve the best possible separation of the gas atmospheres, the slot nozzles must not be too far apart. It has been shown here that, based on the width of the slot nozzles, a minimum distance between the rows of the same width achieves good results, and with a distance of more than twice the width, the risk of poorer separation increases.

Preferred versions of the trunk are characterized in that the slot nozzles have a length l in the transverse direction, the length l being in the range of 20 * b l 50 * b, preferably in the range of 30 * b l 35 * b .

In further versions of the trunk, the injection units and / or suction units are divided into a plurality of sections in the transverse direction, each section comprising its own centered line for supplying or removing protective gas. As a result of this division into sections of the same width, the flow conditions are further improved over the width of the trunk and, in addition, the required power per line is reduced. Versions of the trunk are characterized in that the injection units and / or suction units have a semicircular cross section. Rounded cross-sections have geometries that are advantageous in terms of flow technology. Furthermore, the cross section of the trunk to be sealed is reduced by an injection or suction unit placed on the trunk wall.

The fact that the trunk is heated or at least insulated in order to minimize metal dust deposition on the inner wall of the trunk corresponds to the state of the art and is taken for granted.

Brief Description of Drawings

Fig. 1:

eine Seitenansicht eines Rüssels in einer schematischen, erfindungsgemäßen Ausführungsform,

Fig. 2:

eine schematische Einblaseinheit senkrecht zur Materialflussrichtung betrachtet und

Fig. 3:

ein Ausführungsbeispiel einer Absaugeinheit.

The invention is explained in more detail below with reference to schematic drawings, components of the same type being provided with the same reference numerals. Show in detail:

Fig. 1:

a side view of a trunk in a schematic embodiment of the invention,

Fig. 2:

a schematic injection unit viewed perpendicular to the direction of material flow and

Fig. 3:

an embodiment of a suction unit.

Description of the Preferred Embodiments (Best Mode for Carrying out the Invention)

Fig. 1 shows an embodiment of a trunk (9) according to the invention from the side. A lower section of the trunk (9) is shown, in which the material flow direction (M) runs from top to bottom when installed. The trunk (9) is provided on both sides of the flat product (not shown) with blowing units (1) and suction units (3) extending over the width of the trunk (9), the left side being shown in the closed position and the right side in the open position. The injection units (1) and suction units (3) are each arranged on a carrier plate (8).

The support plate (8) is movably fastened with joints (10) on the counter plate (12) which is connected to the frame (11). The joint (10) can also on the frame (11), the Trunk (9) or more of these parts can be connected. As shown, the joints (10) are preferably provided on the lower edge seen in the direction of material flow (M), which means that it can be opened downwards and placed on the delimitation means (17). The joints (10) can also be provided on other edges of the carrier plate (8) and also have other designs. For example, guide rails in which projections connected to the support plate (8) are guided can also be used as hinge (10).

The limiting means (17) limits the possible range of movement of the carrier plate (8) and thus defines the open position. As shown, the limiting means (17) can be designed as a stop attached to the trunk (9) on which the carrier plate (8) is placed and which limits its opening angle. Alternatively, the limiting means (17) can of course also be provided on the carrier plate (8) or the frame (11). Also a movable traction means with a corresponding fixed length, such as an articulated lever, chain or rope, which are connected to the edges of the carrier plate (8) without a joint (10) and correspondingly to the counter plate (12), frame (11) or trunk (9), can be provided as limiting means (17). The limiting means (17) can also be provided in the joint (10), for example in a guide rail or the like. In addition to the defined open position, the limiting means (17) also prevent damage to the lines (6) of the injection unit (1) and suction unit (3) or adjacent attachments (20), such as a dew point unit (20) shown on the trunk (9). avoided.

In the closed position, the carrier plate (8) and the counter plate (12) contact each other and form a sealing area (18) with which the trunk atmosphere is separated from the environment. Sealing means suitable for this temperature range are provided in the sealing area (18). In order to ensure good sealing of the sealing area (18) and to fix the closed position, closure means (16) are provided.

The closure means (16) are provided at least on the edge opposite the joints (10), but can also be arranged distributed over several edges. The closure means (16) preferably have a tensioning effect which press the carrier plate (8) and the counterplate (12) onto one another. in the Fig. 1 In the example shown, this is achieved by a plurality of eyebolts distributed over the width, which are pivotably attached to the frame (11), engage in clamping straps attached to the support plate (8) and are tightened with screwed-on nuts. Other clamping devices such as wedges, bevels or levers are also possible.

In the in Fig. 1 In the illustrated embodiment, the injection unit (1) arranged in the closed position within the trunk (9) and the suction unit (3) adjacent downstream in the material flow direction (M) are attached to a common cover plate (14). This cover plate (14) ensures that the injection unit (1) and suction unit (3) are positioned relative to one another. In addition, this results in a double-walled structure in the frame (11) with the carrier plate, which improves the sealing and thermal insulation. The wall of the trunk (9) preferably has a protrusion (13) which protrudes into the frame (11), in particular in the direction of material flow (M). In the closed position, the cover plate (14) comes into contact with the protrusion (13), which further improves the positioning and the sealing.

The cover plate (14) and the carrier plate (8) can be made in one piece or connected directly to one another. In preferred embodiments, however, the carrier plate (8) and the cover plate (14) are spaced apart from one another by a corresponding configuration and / or spacers, in particular between the carrier plate (8) and cover plate (14), especially in the area of the injection unit (1) and suction unit ( 3) an insulating material (15) is provided.

Lines (6) are provided for the supply and discharge of gas quantities to the injection units (1) and suction units (3), which extend from the injection unit (1) and suction unit (3) or the cover plate (14) through the carrier plate (8 ) extend outwards. In preferred versions, as well as in Fig. 1 shown, the lines (6) each have a flange (19) in order to simplify the connection to channels for gas quantities to be injected or extracted. After passing through the carrier plate (8), the lines (6) are provided with bends, whereby the flanges (19) of adjacent lines (6) can be spatially separated from one another. The arcs here have an angle of 30 ° to 90 ° degrees. The arches are more preferably aligned parallel to the edge with the joints (10) or in a direction pointing away from this edge and are firmly connected to the carrier plate (8). The connection with the carrier plate (8) is gas-tight and torsion-proof, for example by means of a weld seam.

Fig. 2 shows a schematic representation of an injection unit (1) according to the invention, seen perpendicular to the material flow direction M, more precisely perpendicular to the plane of the flat product conveyed through. Here, two rows of slot nozzles (2) are shown, each with interruptions or have spaces between the slot nozzles (2). The slot nozzles (2) each have a width b and a length l. The two rows of slot nozzles (2) are at a distance a from one another in the direction of material flow M. The slot nozzles (2) of adjacent rows are offset from one another so that a slot nozzle (2) of the adjacent row is assigned to an interruption in one row. The slot nozzles (2) are made longer than the intervening interruptions so that, viewed in the material flow direction M, there is an overlap u of the ends of the slot nozzles (2). The overlap u is formed uniformly along the injection unit (1).

In Fig. 3 a partial area is shown which shows the lower injection unit (1) and suction unit (3) as well as parts of the upper injection unit (1) and suction unit (3) in the trunk (9) of an exemplary embodiment. The two opposite injection units (1) on the upper and lower wall of the trunk (9) are shown as well as the suction units (3) located behind them in the direction of material flow M, that is, downstream. In this illustration it can be seen that the slot nozzles (2) of the injection units (1) are arranged offset from one another. In addition to the offset between the rows on a blowing unit (1), as already described in Fig. 2 shown is in Fig. 3 the offset of the slot nozzles (2) in relation to the opposite injection unit (1) is also shown. In the example shown, the outermost slot nozzle (2) of the lower injection unit (1), viewed in the width direction of the trunk (9), is in the front, i.e. upstream, row and the rear, i.e., downstream, row begins with an interruption. Correspondingly, the outermost slot nozzle (1) is arranged in the rear row of the upper injection unit (1) and the front row begins with an interruption. Thanks to this arrangement, the protective gas exiting the slot nozzles (2) reaches the opposite trunk wall unhindered, more precisely to the opposite blow-in unit (1) or the material surface of the flat product, and the protective gas flows only touch the unavoidable areas of the jet widening . With this configuration, a gas curtain is achieved which is very stable and has a very good sealing effect.

In the example shown, the Fig. 3 Both the suction units (3) and the blow-in units (1) are divided into several areas by partition walls (7) viewed in the width direction. For the discharge or supply of protective gas to the suction units (3) or injection units (1), these each have lines (6) which are shown in FIG Fig. 3 are each indicated by round connection openings for the lines (6). Furthermore In the example shown, the injection units (1) and the suction units (3) are each designed with a semicircular cross-section, which has fluidic advantages by avoiding sharp edges.

Next shows Fig. 3 a preferred embodiment of a suction unit (3). The main openings (4) are aligned in the direction of material flow M in order to generate a circulating flow behind the injection unit (1). The main openings (4) in the area of the lines (6) are designed with a greater height in order to achieve relatively homogeneous flow conditions over the width. The height of the main openings (4) can change continuously or, as in the example shown, abruptly. Additional openings (5) are preferably provided on the top of the suction units (3). In addition to improving the suction, this also enables the area of the circulating flow to be shortened, which reduces the installation space required in the trunk (9) and promotes the circulating flow. The additional openings can be designed with a uniform height across the width of the suction unit, or else, analogous to the main openings (4), with different heights. For the example in a trunk of a hot-dip coating system, the injection units (1) and suction units (3) can be designed with a radius of 40mm, for example, and the height of the main openings (4), for example, in the range from 10 to 15mm and the height of the additional openings (5 ) are around 8mm. In this example, the lines (6) can then have a diameter of approx. 60 mm.

The various features of the invention can be combined with one another as desired and are not limited to the described or illustrated examples of embodiments.

List of reference symbols

1

Injection unit

2

Slot nozzles

3

Suction unit

4th

Main opening

5

Additional opening

6th

management

7th

Partition

8th

Carrier plate

9

Trunk

10

joint

11

frame

12

Counter plate

13

Got over

14th

Cover plate

15th

insulating material

16

Closure means

17th

Limiting means

18th

Sealing area

19th

flange

20th

Attachments / dew point unit

a

distance

b

width

I.

length

u

overlap

M.

Material flow direction

Claims (11)

1. Snout (9) for a hot-dip coating system for a flat product, the snout extending from the outlet of a continuous furnace into a melt below the coating bath surface and insulating the flat product from the environment, wherein at least one suction unit (3) and a blow-in unit (1) are provided, characterized in that the blow-in unit (1) and the suction unit (3) are provided on a common carrier plate (8), in that the carrier plate (8) is connected along an edge via at least one joint (10) to the snout (9), and in that the carrier plate (8) is movable into a closed position in which the carrier plate (8) closes an opening on the snout (9) and an open position.
2. Snout (9) according to Claim 1, characterized in that the opening in the snout (9) is formed by a frame (11), wherein the frame (11) has an encircling counter plate (12) which is in contact with the carrier plate (8) in the closed position.
3. Snout (9) according to Claim 2, characterized in that the frame (11) has a greater length at least in the longitudinal direction of the snout (9) than the recess in the wall of the snout (9) so that there is a projecting length (13) of the wall of the snout (9) within the frame (11).
4. Snout (9) according to Claim 3, characterized in that the blow-in unit (1) and suction unit (3) are mounted on a cover plate (14) which is connected to the carrier plate (8), and in that the cover plate (14) overlaps at least in regions with the projecting length (13) of the wall of the snout (9) within the frame (11).
5. Snout (9) according to Claim 4, characterized in that an insulating material (15) is arranged between the carrier plate (8) and the cover plate (14).
6. Snout (9) according to one of Claims 1 to 5, characterized in that closure means (16) for the releasable fastening to the snout (9) or to the frame (11) are provided at least along a further edge of the carrier plate (8).
7. Snout (9) according to one of Claims 1 to 6, characterized in that a limiting means (17) by which the open position is defined is provided on the carrier plate (8), the snout (9), the frame (11) or the joint (10).
8. Snout (9) according to one of Claims 1 to 7, characterized in that the carrier plate (8) has an encircling sealing region (18) which, in the closed position, overlaps with the wall of the snout (9) or the counter plate (12) of the frame (11).
9. Snout (9) according to one of Claims 1 to 8, characterized in that the blow-in unit (1) and suction unit (3) is each connected to at least one line (6), which is centered over the width, for supplying or removing gas, in that the lines (6) are guided outward through the carrier plate (8) and are connected fixedly to the carrier plate (8), and in that the lines (6) are each provided with a flange (19).
10. Snout (9) according to Claim 9, characterized in that the lines (6) have an arc on the outside, and adjacent arcs are oriented in different directions.
11. Snout (9) according to one of Claims 1 to 10, characterized in that the at least one blow-in unit (1) and a suction unit (3) each extend on both sides of the flat product on opposite walls over the transverse extent of the snout (9), in that the blow-in units (1) are provided directly opposite, in that the blow-in units (1) each comprise at least two rows of a plurality of slotted nozzles (2) with interruptions located in between, wherein the slotted nozzles (2) of the rows are arranged offset with respect to one another, and wherein the interruptions are shorter than the slotted nozzles (2) of the adjacent row so that the slotted nozzles (2) of the rows overlap in the material flow direction (M), and in that the slotted nozzles (2) of a blow-in unit (1) are each opposite an interruption of the opposite blow-in unit (1).

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