EP3419778A1 - Nozzle row arrangement and nozzle field for installing in a roller gap between two strand guide rollers - Google Patents

Abstract

The invention relates to a nozzle row arrangement and to a nozzle field for installing in a roller gap (212) between two strand guide rollers (214) in a strand guide (210) of a strand casting plant. Known nozzle row arrangements typically have at least one one-material nozzle (110) in a center region G of the roller gap (212) and at least one further nozzle (120) to the right and to the left of the center region in the roller gap, as viewed in the casting direction R. The nozzles are used to apply coolant M1, M2 to a cast strand (300) guided by the strand guide rollers (214). In order to improve the quality of the cast strand (300) and at the same time reduce the costs for secondary cooling, the nozzle row arrangement (100) according to the invention provides that the further nozzles (120) to the right and to the left of the center region in the roller gap are designed as multiple-material nozzles, wherein the at least one one-material nozzle has a smaller control ratio than the multiple-material nozzles (120).

Description

 Nozzle row arrangement and nozzle field for installation in roller gaps between two strand guide rollers

The invention relates to a nozzle row arrangement for installation in a roller gap between two adjacent in a casting direction strand guide rollers in a strand guide in a continuous casting. The continuous casting plant is used for pouring liquid metal into a cast strand, which is guided within the strand guide between strand guide rollers. The nozzle array consists of a plurality of nozzles for applying coolant to the casting strand. The invention further relates to a nozzle array, which is a plurality of nozzle array arrangements, which in a plurality of

Roller gaps are arranged in the strand guide. In the prior art series arrangements of coolant nozzles are well known, such. B. from German Patent Application DE 10 2009 005 679 A1. There it is mentioned that the nozzles can be either 1-fluid nozzles or 2-fluid nozzles per roller gap. As the labels indicate, the 1-fluid nozzle applies only a single coolant to the casting strand, while the 2-fluid nozzles are designed to mix two coolants, typically air and water, previously mixed in a mixing chamber were sprayed onto the cast strand.

German Auslegeschrift 26 36 666 discloses nozzles for coolant in a series arrangement, wherein the nozzles are arranged there symmetrically to a plant center or strand central axis of the strand guide.

A continuous casting plant typically comprises a mold and a strand guide arranged downstream of the mold in the casting direction with a plurality of

Strand guide rolls. After liquid metal, in particular liquid steel was filled into the mold, it is at the edges of the mold by means of a Cooled primary cooling, so that there forms a cast strand with initially still liquid core but already solidified stable strand shell within the mold. After the cast strand leaves the mold with a viable shell, it is guided within the downstream strand guide and cooled until it is finally completely solidified. The guide within the strand guide takes place between opposite strand guide rollers, wherein the casting strand is typically bent from the vertical to the horizontal. The cooling of the casting strand in the strand guide takes place with the said nozzle row arrangements between the roller gaps. For cost reasons (operating and installation costs) 2-fluid nozzles are used only in certain cases, namely in particular where the ejected from the nozzle

Coolant flow in a wide control range, hereinafter also called control ratio, must be adjustable. This requirement may arise in particular if the continuous casting plant is designed for a large product spectrum, ie. H. for the casting of casting strands of very different widths or different steel grades with widely varying casting speeds. 1 - Substance nozzles are much more limited in their control ratio than 2-component nozzles, and therefore they are suitable for installation in

Continuous casting plants that are designed for a wide range of products, at least not suitable on their own.

The invention is based on the object, a known nozzle row arrangement and a known nozzle array for installation in roller gaps between

To develop strand guide rollers to the effect that on the one hand a

Improve the quality of the cast strand, but on the other hand are more cost-effective.

This object is achieved for the nozzle row assembly by the subject of claim 1. Accordingly, the invention

Nozzle row arrangements characterized in that the further nozzles as Multi-substance nozzles are formed whose control ratio is greater than the control ratio of the at least one 1-nozzle.

The term 1-piece nozzle states that these nozzles are operated with only a single coolant, typically water. The term multicomponent nozzles analogously means that these nozzles are operated with a plurality of coolants. A multi-substance nozzle according to the invention preferably means a 2-material nozzle, which typically with a gaseous material M2, z. As air or nitrogen, and in addition with a liquid M1, z. B. be operated with water.

The control ratio, also called the control range, of a nozzle indicates how far the volume flow of the coolant can be lowered in relation to a nozzle-specific nominal or maximum value specified by the manufacturer, without the spray pattern or the jet cone suffering substantially or even

collapses.

The claimed nozzle row arrangement provides that in a central region of the roller gap only 1-fluid nozzle are installed, while right and left of the central region, d. H. Multi-substance nozzles are installed in the edge regions of the casting strand. Due to the sprayed from the multi-substance nozzles

Coolant mixture of, for example, a gaseous and a liquid coolant, the control range of the multi-fluid nozzles is typically significantly greater than the control range of the 1-fluid nozzles. However, the purchase and operation of the multi-fluid nozzles are significantly more expensive than the operation of the 1-fluid nozzle, because the provision of the gaseous coolant, for. B. compressed air is many times more expensive than the provision of water as a coolant.

In the present case, it is the merit of the inventors to have realized that even for the operation of a continuous casting plant, which is intended for a broad product spectrum and therefore requires a wide cooling power spectrum, it does not it is necessary to provide multi-substance nozzles over the entire width of the roll gap. Rather, it is sufficient to provide such multi-component nozzles with a large control range only in the edge region of the cast strand. In this way it is possible to produce a variety of different grades of steel,

In particular, to spray crack-sensitive steel grades with good surface quality, at the same time comparatively low cost of the coolant. The fact that the expensive in their operation multi-component nozzles only in

Edge region of the casting strand and are not located in the center region, the operating costs compared to a consistently equipped with multi-nozzle nozzle row arrangement are significantly lower. The quality of a

Gießstrangs and in particular its surface is not characterized

limited that are used in the central area only in both the purchase as well as maintenance inexpensive 1-fluid nozzle. The claimed nozzle row arrangement is preferably used in continuous casting plants with the following specifics:

System types: vertical bending, curved and vertical slab systems

 Slab widths: 1000 - 4000 mm

 Slab thicknesses: 40 - 700 mm

 Casting speeds: 0.1 - 10 m / min

 Strand guide length: 1 - 50 m

 Nozzle distance to the slab: 50 - 1000 mm

 Spray angle width: 30 - 160 degrees

 Spray angle depth: 1 - 120 degrees

 Single media: water, air, nitrogen

 Mixture media: water / air; Water / nitrogen

Water admission density 1 - 100 l / (m ² s)

Heat transfer coefficients 300 - 60000 W / (m ² K); Heat-Temperature-Coefficient HTC Basically it is important that all nozzles in one

Nozzle row arrangement are designed for a same maximum heat-temperature-Coefficient HTC value, regardless of whether it is 1-material or multi-component nozzles. Therefore, this advantageous condition applies in particular in the transition region from the central region G to the edge regions, if there 1-substance and multi-component nozzles are arranged adjacent to each other. The nozzle row arrangement according to the invention can be used for cooling the upper side or the lower side of a cast strand.

Further advantageous embodiments of the claimed nozzle row arrangement are the subject of the dependent claims.

The above object of the invention is further achieved by a nozzle field for installation in roller gaps between a plurality of strand guide rollers arranged adjacent in the casting direction according to claim 5. The advantages of this solution correspond to the advantages mentioned above with respect to the nozzle row arrangement.

Advantageously, in a nozzle field, the entire spray width, and thus preferably also the number of nozzles per roll gap, decreases from outside to inside in the casting direction. Such a configuration of the nozzle rows in the

Nozzle fields is possible and useful because generally the required

Cooling power decreases in the casting direction with increasing solidification. With the appropriate reduction in the number of nozzles can both

Acquisition and operating costs are advantageously saved. The number of nozzles does not have to be reduced from each roller gap to the subsequent roller gap immediately adjacent in the casting direction. Rather, several successive in the casting direction roller gaps can be the same Having a number of nozzles, and only - the plurality of roller columns - downstream roller gaps then have a reduced number of nozzles. In this respect, the terms first and second roll nip are not necessarily to be understood as adjacent roll nips.

The description is accompanied by four figures, wherein Figure 1 shows a continuous casting plant according to the prior art; FIG. 2 shows a nozzle row arrangement according to the invention;

FIG. 3 shows different control ratios of 1-substance and multi-substance

nozzles; and Figure 4 shows a nozzle array according to the invention.

The invention will be described in detail below with reference to the said figures in the form of embodiments. In all figures, the same technical elements are designated by the same reference numerals.

FIG. 1 shows a conventional continuous casting plant 200, which essentially consists of a continuous casting mold 250 and one of the continuous casting molds

Strand guide 210 consists. After filling a liquid metal,

typically steel, a bath level 252 forms within the mold. The liquid metal is cooled in the mold 250 by means of a primary cooling (not shown) so that a cast strand 300 is formed there. The cast strand is initially fluid in its interior; However, it forms on its outside a solidified solid strand shell 310. After leaving the mold 250, the casting strand 300 in the strand guide 210 between opposite strand guide rollers 214 out. The guide takes place in Figure 1 from top to bottom, ie here in the casting R.

Within the strand guide 210, the cast strand 300 is supplied with coolant (secondary cooling). This is done by means of nozzles in the form of nozzle row assemblies 100 in the roller gaps 212 between two in

Casting R adjacent strand guide rollers 214 are arranged. As a result of the application of coolant, the cast strand 300 solidifies continuously during its guidance through the strand guide 210, until it finally completely solidifies.

FIG. 2 shows a cross-section through a roller gap 212. The casting strand 300 can be seen in the partially solidified state, that is to say the casting strand 300 is in the partially solidified state. H. with a solidified

Strand shell 310 and a still liquid core 320. Above the Gießstrangs the nozzle row assembly 100 can be seen. Specifically, the

 Nozzle row arrangement in the example shown here four 1-nozzle nozzles 1 10, which are each operated only with a liquid cooling medium M1, typically water. All four 1-fluid nozzles are preferably for the same maximum HTC value, i. H. designed for the same maximum cooling capacity. In simple terms, this means that all 1-substance nozzles apply the same amount of liquid per unit of time to the cast strand 300 to be cooled. The strand guide is configured to guide the casting strand 300 with format widths between a minimum format width and a maximum format width. The arrangement of the 1 - substance nozzles is limited to the center region G. For the width of the

Center area G applies according to the present invention:

100 mm <width of center area G <minimum format width of

Strand guide. As can also be seen in FIG. 2, the center region G extends symmetrically to a plant center GO of the strand guide 210 in the roll gap 212. The 1-material nozzles 110 are also within the center region G.

arranged symmetrically to the plant center GO in the roller gap 212.

Right and left of the central region G is here, for example, each a 2-material nozzle 120 arranged as a multi-component nozzle within the nozzle row assembly 100. The 2-material nozzle is operated with two coolants M1, M2. The first coolant M1 is typically liquid, e.g. Water. The second coolant M2 is typically gaseous, e.g. Air. That's why you are

 Control range significantly larger. This is particularly advantageous because a finer or more demand-oriented adjustment of the cooling capacity in the

Edge regions of the casting strand is made possible. As can be clearly seen in FIG. 2, the 2-material nozzles 120 only deliver a significantly smaller amount of liquid coolant per unit time onto the cast strand. Even if the

Cooling effect on the edges is influenced not only by the liquid cooling medium, but in addition by the gaseous medium, so the overall cooling capacity of the 2-fluid nozzles in the edge regions, however, is usually deliberately set much lower than that of the 1 - Substance nozzles 1 10 in the central region G to be provided cooling capacity. This is because, as stated, the edge portions of the cast strand 300 must be "kept warm" to avoid cracking Therefore, the 2-material nozzles provided for the edge region may also be designed for a smaller maximum HTC value than the others Nozzles of the nozzle row.

FIG. 3 illustrates the different control ratios of 1-substance and 2-substance nozzles. If both nozzles are designed for the same maximum cooling capacity (Heat-Temperature-Coefficient HTC), then the 2-material nozzle advantageously enables, unlike the 1-material nozzle, the setting of significantly lower cooling capacities than the 1-material nozzle. Jet. Based on these Feature recommend 2-fluid nozzle for use in continuous casting, which are designed for a wide range of different grades of steel.

By way of example, for a specific 1-nozzle nozzle, on the one hand, a specific cooling capacity specified by the manufacturer (corresponds approximately to one

predetermined maximum volume flow of liquid coolant) and, secondly, a control ratio of, for example, 1: 6. This means that the volume flow of, for example, a maximum of 6 L / min should be lowered to 1 L / min, without the spray cone and the spray pattern of the nozzle would suffer significantly.

In contrast, a control ratio of 1:20 for a 2-material nozzle, assuming the same maximum permissible flow rate of 6 l / min as an example, would mean that the volume flow should be reduced to 6/20 = 0.3 l / min (minimum permissible value) without the spray cone and the spray pattern of the 2-material nozzle would suffer significantly. Because the (minimum permissible) volume flow of coolant compared to a 1-fluid nozzle can be lowered significantly further, the cooling performance of the 2-fluid nozzle can be reduced significantly further, compared to a 1-fluid nozzle.

However, the present invention shows that it is sufficient if these expensive 2-fluid nozzles are used in their operation only in the edge regions and not over the entire width of the roller gap. FIG. 4 shows a nozzle field according to the invention, which consists of a plurality of nozzle row arrangements. The nozzle field 400 comprises in particular a first nozzle row arrangement 100-1 in a first roll gap 212 and a second nozzle row arrangement 100-2 in a second roll gap, which is arranged downstream of the first roll gap in the casting direction R in FIG. Overall, the nozzle array 5 shown in FIG. 4 comprises nozzle rows, the first, second and third nozzle row arrangement according to the present invention being shown by way of example Invention are formed. In concrete terms, this is shown by the fact that these first three nozzle row arrangements have only 1-substance nozzles within the center region G and in each case 2-material nozzles 120 in their edge regions. Because the cooling capacity required with increasing length of the strand guide due to the increasing solidification of the casting strand in the casting direction is lower, and the total spray width B of all nozzles 1 10, 120, 120 'per

Rolling gap 212 in the casting direction R are increasingly lower. As the overall spray width becomes smaller, the number of nozzles per roller gap also decreases from outside to inside, as can be seen in FIG. The decrease in the number of nozzles per roller gap, for example, finally goes so far that in the fourth roller gap only three 1-fluid nozzle and in a fifth roller gap finally only a 1-fluid nozzle in the central region G are arranged / is , The nozzle row arrangements in the fourth and fifth roll gaps no longer correspond to the nozzle row arrangement according to the present invention, because right and left outside of the central area G, no 2-substance nozzles are arranged any more.

LIST OF REFERENCE NUMBERS

100 nozzle row arrangement

 100-1 first nozzle row arrangement

 100-2 second nozzle row arrangement

 1 10 1 nozzle nozzle

 120 additional nozzles (= multiple or 2-material nozzle)

 120 'outermost 2-material nozzle

 200 continuous casting plant

 210 strand guide

 212 roller gap

 214 strand guide roller

 250 continuous casting mold

 252 bathroom mirror

 300 cast strand

 310 solidified strand shell

 320 liquid core

 400 nozzle field

 B Total spray width of all nozzles per roller gap

G Width of the center area

 GO Plant center of the strand guide above the casting width

M1 first coolant

 M2 second coolant

 R casting direction

Claims

claims:

1 . Nozzle row arrangement (100) for installation in a roller gap (212)

 between two strand guide rollers (214) adjacent to one another in a casting direction (R) in a strand guide (210) of a continuous casting plant (200), comprising:

 at least one 1-nozzle (1 10) with a first control ratio, arranged in a central region (G) of the roller gap (212), and in each case at least one further nozzle (120), arranged - seen in the casting direction - right and left of the central region in the roll nip;

 wherein the at least one 1-fluid nozzle and the further nozzles

 are formed for applying coolant (M1, M2) on one of the strand guide rollers (214) guided casting strand (300);

 characterized,

 that the further nozzles (120) are designed as multi-substance nozzles each having a second control ratio; and

 that the first control ratio is smaller than the second control ratio.

2. nozzle row arrangement (100) according to claim 1,

 characterized in that

 the strand guide (210) is adapted to guide casting strands (300) having format widths between a minimum format width and a maximum format width; and

 for the width of the middle range applies:

 100mm <width of middle area (G) <minimum width of width of strand guide.

3. nozzle row arrangement (100) according to one of the preceding claims, characterized in that

the center region (G) is symmetrical to a plant center (G0) of the Strand guide (210) extends in the roll nip; and

 the at least one 1-fluid nozzle (110) and the multi-fluid nozzles (120) are arranged symmetrically to the middle of the plant (GO) in the roller gap (212).

4. nozzle row arrangement (100) according to claim 1,

 characterized in that

 if two or more multi-substance nozzles (120) are arranged to the right and left of the center region (G) - except for the two outermost multi-substance nozzles (120 ') which also cover the right and left edge of the respective casting strand with their spray area - all remaining multi-component nozzles (120) are designed for the same maximum heat-temperature-coefficient HTC value as the at least one 1-nozzle (1 10) in the central region (G).

5. nozzle field (300) for installation in roller gaps (212) between a plurality of in the casting direction (R) arranged adjacent strand guide rollers (214) in a strand guide (210) of a continuous casting plant (200), wherein the nozzle array (300) comprises:

 a first nozzle row assembly (100-1) in a first roller nip; and a second nozzle row arrangement (100-2) in a second roller gap, which is arranged downstream of the first roller gap in the casting direction, wherein at least the first nozzle row arrangement (100-1) is formed according to one of the preceding claims.

6. nozzle array (300) according to claim 5,

 characterized in that

the total spray width (B) of all nozzles per roller gap decreases in the casting direction (R). A nozzle field (300) according to claim 6,

characterized in that

the number of nozzles per roller gap decreases from outside to inside casting direction.