EP3419778B1 - Nozzle row arrangement and nozzle field for installing in a roller gap between two strand guide rollers - Google Patents

Description

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 arrays disposed in a plurality of roll nips in the strand guide.

In the prior art series arrangements of coolant nozzles are well known, such. B. from the 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, in the 1-material nozzles only a single coolant is applied to the casting strand, while the 2-material 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 range, ie for the casting of casting strands of quite different widths or different steel grades with greatly varying casting speeds. 1-fluid nozzles, in contrast to 2-fluid nozzles in their control ratio significantly more limited, and therefore they are not suitable for installation in continuous casters, which are designed for a wide range of products, at least alone.

The invention has the object of developing a known nozzle array and a known nozzle array for installation in roller gaps between strand guide rollers to the effect that on the one hand to 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 nozzle array arrangements according to the invention are 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-substance nozzle.

The term 1-fluid nozzle states that these nozzles are only operated with 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 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 jet cone suffering substantially or even collapsing.

The claimed nozzle row arrangement provides that in a central region of the roller gap only 1-fluid nozzles are installed, while right and left of the central region, d. H. in the edge regions of the casting strand multi-component nozzles are installed. Due to the sprayed from the multi-component nozzle coolant mixture of, for example, a gaseous and a liquid coolant, the control range of the multi-fluid nozzles is typically significantly larger than the control range of the 1-fluid nozzles. However, the purchase and operation of the multi-component nozzles are significantly more expensive than the operation of the 1-fluid nozzles, 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 cast a variety of different steel grades, especially crack-sensitive steel grades with good surface quality, at the same time comparatively low cost of the coolant. Due to the fact that the multi-component nozzles which are expensive in their operation are arranged only in the edge region of the cast strand and not in its middle region, the operating costs are significantly lower compared to a nozzle row arrangement equipped with multi-component nozzles. The quality of a cast strand and in particular its surface is not limited by the fact that in the central area only in the purchase as well as in maintenance inexpensive 1-fluid nozzles are used.

The claimed nozzle row arrangement is preferably used in continuous casting plants with the following specifics: Plant forms: Vertical bending, bow and vertical slab plants 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 impingement: 1 - 100 l / (m ² · s) Heat transfer coefficient: 300 - 60,000 W / (m ² · K); Heat-Temperature-Coefficient HTC

In principle, it is important that all nozzles in a nozzle array are designed for the same maximum heat-temperature-coefficient HTC value, whether they are 1-fluid or multi-fluid 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 rows of nozzles in the nozzle fields is therefore possible and useful, because generally the required cooling capacity decreases in the casting direction with increasing through solidification. With the corresponding reduction of the number of nozzles both acquisition and operating costs can be 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.

Figur 1

eine Stranggießanlage nach dem Stand der Technik;

Figur 2

eine erfindungsgemäße Düsenreihenanordnung;

Figur 3

unterschiedliche Regelverhältnisse von 1-Stoff- und Mehrstoff-Düsen; und

Figur 4

ein erfindungsgemäßes Düsenfeld

zeigt.The description is attached to four figures, wherein

FIG. 1

a continuous casting plant according to the prior art;

FIG. 2

a nozzle array according to the invention;

FIG. 3

different control ratios of 1-substance and multi-substance nozzles; and

FIG. 4

an inventive nozzle field

shows.

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 classic continuous casting plant 200, which consists essentially of a continuous casting mold 250 and a strand guide 210 downstream of the continuous casting mold. 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 guided tour takes place in FIG. 1 from top to bottom, ie here in the casting direction R.

Within the strand guide 210, the cast strand 300 is supplied with coolant (secondary cooling). This is done with the aid of nozzles which are arranged in the form of nozzle row arrangements 100 in the roller gaps 212 between two strand guide rollers 214 which are adjacent in the casting direction R. 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. It can be seen the cast strand 300 in teilerstarrtem state, ie with a solidified strand shell 310 and a still liquid core 320. Above the cast strand, the nozzle array 100 can be seen. Specifically, in the example shown here, the nozzle row arrangement comprises four 1-substance nozzles 110 which are each operated only with a liquid cooling medium M1, typically water. All four 1-fluid nozzles are preferably designed for the same maximum HTC value, ie 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 central region G according to the present invention applies:
100 mm <width of center area G <minimum width of width of strand guide.

As in FIG. 2 1, the center region G extends symmetrically with respect to a plant center G0 of the strand guide 210 in the roll gap 212. The 1-substance nozzles 110 are also arranged within the center region G symmetrically to the plant center G0 in the roll 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, eg water. The second coolant M2 is typically gaseous, eg air. For this reason, their control range is much larger. This is particularly advantageous because it allows a finer or demand-oriented adjustment of the cooling capacity in the edge regions of the cast strand. As in FIG. 2 can be clearly seen, give the 2-fluid nozzles 120 only a significantly smaller amount of liquid coolant per unit time on the cast strand. Even if the cooling effect on the edges is influenced not only by the liquid cooling medium but also by the gaseous medium, the overall cooling capacity of the 2-substance nozzles in the edge regions is, as a rule, deliberately set much lower than that of the 1-material nozzles 110 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 remaining nozzles of the nozzle row.

FIG. 3 illustrates the different control ratios of 1-fluid and 2-fluid nozzles. If both nozzles are designed for the same maximum cooling capacity (Heat-Temperature-Coefficient HTC), 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-material nozzle, on the one hand, a specific cooling output specified by the manufacturer (corresponding approximately to a predetermined maximum volume flow of liquid coolant) and, on the other hand, a control ratio of, for example, 1: 6 are specified. 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 lowered 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 allowable) 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 array according to the invention, which consists of a plurality of nozzle array arrangements. In particular, the nozzle field 400 comprises 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 in FIG FIG. 4 downstream of the first roller gap in the casting direction R. Overall, this includes in FIG. 4 shown nozzle array 5 rows of nozzles, wherein, by way of example, the first, second and third nozzle row arrangement according to the present Invention are formed. In concrete terms, this is shown by the fact that these first three nozzle row arrangements have only 1-material nozzles within the center region G and 2-material nozzles 120 in their edge regions.

Because the required cooling capacity decreases with increasing length of the strand guide due to the increasing solidification of the casting strand in the casting direction, the total spray width B of all the nozzles 110, 120, 120 'per roll gap 212 in the casting direction R can also become increasingly smaller. As the total spray width becomes smaller, the number of nozzles per roller gap decreases from outside to inside, as in FIG FIG. 4 can be seen. 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 nozzles 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 array

100-1

first nozzle row arrangement

100-2

second nozzle row arrangement

110

1-component nozzle

120

additional nozzle (= multi or 2-material nozzle)

120 '

outermost 2-material nozzle

200

continuous casting plant

210

strand guide

212

nip

214

Strand guide roller

250

continuous casting

252

Bathroom mirror

300

cast strand

310

solidified strand shell

320

liquid core

400

nozzle array

B

Total spray width of all nozzles per roller gap

G

Width of the center area

G0

Plant center of the strand guide above the casting width

M1

first coolant

M2

second coolant

R

casting

Claims (7)

1. Nozzle row arrangement (100) for installation in a roller gap (212) between two strip guide rollers (214), which are adjacent in a casting direction (R), in a strip guide (21) of a continuous casting plant (200), comprising
   at least one single-substance nozzle (110), which has a first regulating ratio, arranged in a centre region (G) of the roller gap (212), and at least one respective further nozzle (120) arranged in the roller gap on each of the right and left of the centre region as seen in casting direction;
   wherein the at least one single-substance nozzle and the further nozzles are constructed for application of coolant (M1, M2) to a cast strip (300) guided by the strip guide rollers (214);
   characterised in that the further nozzles (120) are constructed as multi-substance nozzles each with a second regulating ratio; and
   the first regulating ratio is smaller than the second regulating ratio.
2. Nozzle row arrangement (100) according to claim 1, characterised in that the strip guide (210) is constructed for guiding cast strips (300) with format widths between a minimum format width and a maximum format width; and for the width of the centre region there applies:
   100 mm < width of the centre region (G) < minimum format width of the strip guide
3. Nozzle row arrangement (100) according to any one of the preceding claims, characterised in that the centre region (G) extends in the roller gap symmetrically with respect to a plant centre (G0) of the strip guide (210); and the at least one single-substance nozzle (110) and the multi-substance nozzles (120) are arranged in the roller gap (212) symmetrically with respect to the plant centre (G0).
4. Nozzle row arrangement (100) according to claim 1, characterised in that when two or more respective multi-substance nozzles (120) are arranged on each of the right and left of the centre region (G) then apart from the two outermost multi-substance nozzles (120'), which by the spray range thereof also cover the righthand and lefthand edges of the respective cast strip, all remaining multi-substance nozzles (120) are designed for the same maximum heat-temperature-coefficient (HTC) value as the at least one single-substance nozzle (110) in the centre region (G).
5. Nozzle field (300) for installation in roller gaps (212) between a plurality of strip guide rollers (214), which are arranged adjacently in casting direction (R) in a strip guide (210) of a continuous casting plant (200), wherein the nozzle field (300) comprises:

   a first nozzle row arrangement (100-1) in a first roller gap; and

   a second nozzle row arrangement (100-2) in a second roller gap downstream of the first roller gap in casting direction,

   wherein at least the first nozzle row arrangement (100-1) is constructed according to any one of the preceding claims.
6. Nozzle field (300) according to claim 5, characterised in that the overall spray width (B) of all nozzles per roller gap decreases in casting direction.
7. Nozzle field (300) according to claim 6, characterised in that the number of nozzles per roller gap decreases in casting direction from the outside to the inside.

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