WO1999036580A1 - Tapping launder for an iron smelt - Google Patents

Abstract

The invention relates to a tapping launder for an iron smelt, comprising an outer support structure (10), a fireproof lining (16, 18) and a copper lining (20) with ducted cooling. Said copper lining (20) surrounds the fireproof lining (18) in the support structure (10). Solid ribs (32) on the copper lining (20) project deep into the fireproof lining (18). The main purpose of said ribs is to cool any iron smelt which penetrates through cracks in the fireproof lining (18) to hardening, hereby stopping said smelt before it comes into contact with the solid copper base body. This prevents cracks caused by overheating from forming in the solid copper base body, hereby reducing the risk of coolant leaking into the iron smelt.

Description

 Tapping gutter for an iron smelter

The invention relates to a tapping channel for an iron smelter, such as e.g. is used on the blast furnace for tapping the pig iron.

Tapping channels for molten iron have been known for a long time. They essentially consist of an outer support structure (such as a metallic trough) with a refractory lining. The lining usually consists of a permanent lining, e.g. is formed from refractory stones, which are inserted directly into the metallic trough, and a wear lining made of a refractory casting compound, in which the receiving channel for the approximately 1500 ° C warm iron melt is formed. In modern blast furnaces with a production of several thousand tons of pig iron per day, the tapping trough is exposed to heavy loads. Correspondingly - the refractory lining often has to be repaired or replaced.

It is known that the service life of the refractory lining can be improved by cooling. However, the use of cooling circuits with liquid coolants (usually cooling water) in the tapping channel is not without problems. Indeed, if e.g. If the iron melt breaks through the refractory lining, the iron melt and the cooling water, a violent hydrogen explosion can occur. In order to reduce this explosion risk or to eliminate it entirely, several solutions have already been proposed.

For example, it was proposed in EP-A-0060239 to design the outer support structure as a double-walled metallic trough, through the interior of which compressed air is passed as a coolant. Compared to forced cooling with a liquid coolant, forced cooling with air is far less effective. In addition, such compressed air cooling is very energy-intensive. Another disadvantage is that the double-walled trough requires a relatively large amount of production. In DE-A-0143971 it has been proposed to provide box-shaped cooling elements or cooling pipes which are connected to a cooling water circuit on the side of the pouring channel, inside the refractory lining. In order to reduce the risk of explosion, a complex security system has been provided. A copper plate with thermal elements is arranged in the wear lining in front of the cooling elements. The latter are connected to a control circuit which, when a predetermined maximum value of the temperature or the rate of temperature rise is exceeded, blocks the water supply and connects the cooling elements to a compressed air network for the purpose of emergency cooling.

In EP-A-0090761 it was proposed to cover the permanent lining with a highly conductive layer of graphite, semigraphite or silicon carbide stones, which is traversed by cooling tubes through which a liquid coolant is passed. This highly conductive layer is strongly cooled by the liquid coolant, so that the molten iron, which penetrates through cracks to this outer cooling layer, solidifies immediately. The same patent application also indicates that the graphite, semigraphite or silicon carbide stones could also be replaced by copper, iron or cast iron plates and that the cooling tubes could be embedded in a highly conductive material.

Because of the high conductivity of the copper, copper plates with cooling channels integrated directly into the copper seem to be a particularly interesting solution. However, until now, iron tunnels hot at 1500 ° C have not been used for a forced-cooled copper lining. It is expected that if the molten iron breaks through to the copper lining, the molten iron will immediately solidify. It is feared, however, that the direct contact of the molten iron with the force-cooled copper lining leads to overheating which can cause coolant to escape into the molten iron. The present invention has for its object to provide a positively cooled tapping trough with a copper lining in which the risk of coolant escaping into the iron melt is greatly reduced.

A tapping channel according to claim 1 is a possible solution to this problem. Such a tapping channel comprises an outer support structure with a refractory lining in which a channel for the iron melt is formed. A solid copper lining, which is forced-cooled by a cooling device, surrounds the refractory lining in the support structure. Its function is to cool the inner refractory lining and thereby extend its service life. It also protects the outer support structure against overheating. According to an important feature of the present invention, this copper liner has solid ribs which protrude from the solid copper base body into the refractory lining. Of course, these ribs improve the cooling effect in the refractory lining and thus its service life. However, the main function of these ribs is to protect the solid copper base body from the penetration of molten iron into the refractory lining. This protective function is mainly fulfilled by the fact that the iron melt which has penetrated is strongly cooled by the ribs until it solidifies and is therefore stopped before it comes into contact with the solid base body made of copper. This avoids overheating cracks in the solid copper base body and thus reduces the risk of coolant escaping into the iron melt. It should be noted that contact between the molten iron and the rib can cause local overheating or partial melting of the rib, but this generally does not have any significant negative effects on the actual copper base body.

The refractory lining is advantageously cast onto the copper lining, at least in the area of the ribs. As a result, the heat transfer between the refractory lining and the copper lining in the area of

Ribs improved. Cavities and gaps through which the molten iron could penetrate to the copper lining are more effectively avoided. The copper lining is preferably formed by solid copper plates, which are advantageously continuously cast. A length section of the tapping channel can consist, for example, of a base plate and two side plates made of copper. In a first embodiment, the cooling device comprises cooling channels in the copper lining, each of the cooling channels being covered in each case by a rib. The location of the cooling channels under the massive fins further reduces the risk of coolant escaping into the molten iron.

The fins and cooling channels preferably run parallel to the longitudinal direction of the tapping channel. This reduces the number and length of the external connections between the cooling channels. Furthermore, in the case of continuously cast copper plates, this arrangement allows the cooling channels to be formed as inserts in a continuous casting mold as through-channels in the casting direction and / or the ribs to be formed by battlements in the continuous casting mold.

A further solution to the specified task can be that the cooling device, instead of cooling channels in the copper lining, has an external cooling circuit which externally, i.e. cools from the back facing the support structure. This solution also enables a reduction in the risk of coolant leakage into the molten iron. The massive copper liner made of copper does indeed form an extremely effective shield that effectively prevents the cooling liquid and molten iron from coming together. Small cracks in the solid copper lining are hardly a danger here. Such an external cooling circuit can, for example, a spray device for

Spray the back of the copper liner with a coolant. It should be noted in this regard that, when encountering an iron melt, finely sprayed water, for example, represents a far lower risk than a compact water jet resulting from a leak in a cooling channel! exit. To cool the copper lining through the To improve the spray device, the back is advantageously enlarged by furrows.

However, such an external cooling circuit can also comprise external cooling elements, through which a cooling liquid flows and which are thermally conductively connected to the back of the copper lining. In a first embodiment, these cooling elements are designed as solid copper beams with integrated cooling channels. In an alternative embodiment, these cooling elements are designed as swirl chambers, which are arranged perpendicular to the back of the copper lining. It should be noted that cooling circuits, which cover the copper lining from the outside, i.e. Cool from the back, can of course be used with or without ribs on the inside of the copper lining (i.e. towards the refractory lining).

Further advantages and features of the present invention can be gathered from the following description of some exemplary embodiments of

Derive tapping troughs, which is made using the attached drawings.

Show it:

Figure 1 shows a cross section through a first embodiment of a tapping trough; Figure 2 shows a cross section through a second embodiment of a tapping trough;

Figure 3 shows a cross section through a third embodiment of a tapping trough, which is partially drawn in perspective;

FIG. 4: a cross section through a fourth embodiment of a tapping groove, which is partly drawn in perspective, only the right half of the groove being shown;

Figure 5 shows a cross section through a fifth embodiment of a tapping groove, which is partially drawn in perspective, only the right half of the groove being shown; Figure 6: a diagram showing the temperature profile in cross section of a tapping trough with ribs.

In the figures 1 to 5 tapping channels for an iron smelter are shown, as they are e.g. be used on the blast furnace for tapping the pig iron. They comprise a support trough 10, in which a channel 12 for the approximately 1500 ° C. warm iron melt 14 is formed in a refractory lining 16, 18. The latter usually consists of a wear lining 16, in which the channel 12 is formed, and a permanent lining 18, which surrounds the wear lining 16. A copper lining 20, 120, 320, 420 is arranged between the permanent feed 18 and the support trough 10 and is forced-cooled by means of a cooling device. This positively cooled copper lining 20, 120, 320, 420 protects the support trough 10 against overheating and thus against thermal deformation. If the tapping channel is arranged in a concrete channel, it also protects the concrete and its fittings against thermal overload. It also cools the refractory lining 16, 18 and thereby increases its service life. This is particularly true for the refractory lining 18. In a tapping channel in a cast concrete channel, this concrete channel can take over the supporting function of the support trough 10, so that the copper lining 20, 120, 320, 420 can be arranged directly between the concrete walls and the permanent lining 18. Thermal insulation may also be provided between the copper lining 20, 120 and the support structure 10 (see, for example, the insulating plates provided with the reference number 21 in FIG. 3). It should be noted that the cross section of the channel formed by the support trough 10 (or the concrete channel) determines the shape of the copper lining 20, 120, 220, 320, 420. A preferred form of this cross section is shown in the figures. Of course, the embodiment of the invention is not limited to the cross-sectional shape shown.

In the embodiment according to FIG. 1, the copper lining 20 consists of, essentially vertical, side plates 22 and 24, and essentially horizontal, bottom plates 26. These elongated plates 22, 24, 26 are assembled in such a way that they form a kind of copper trough 20 for the Form refractory lining 16, 18. The reference numbers 28 and 30 in FIG. 1 denote the seams between the side plates 22, 24 and the base plate 26. Since the length of the individual copper plates 22, 24, 26 is usually much shorter than the length of the tapping channel, a plurality of side plates 22, 24 or bottom plates 26 must of course be lined up in order to line the support trough 10 over its entire length.

According to an important feature of the present invention, the copper plates 22, 24, 26 have on their inner surface, i.e. the surface facing the refractory lining has massive ribs 32 which project substantially into the inner refractory lining 18. The ratio of the height "H" of the ribs 32 to the thickness "D" of the permanent feed 18 should preferably be between 1: 4 and 3: 4. The ribs 32 preferably extend over the entire length of the copper plates 22, 24, 26 and are separated by grooves 34. They contribute to a significant improvement in the cooling of the refractory lining. In particular, the temperatures in the permanent feed 18 are significantly reduced. A no less important function of the ribs 32 is to cool the iron melt until it solidifies in the event of a local breakthrough of the iron melt 14 into the permanent feed 18, before it comes into contact with the actual base body made of copper and causes deep overheating cracks therein. It should be noted that contact between a fin 32 and the molten iron, local overheating or even partial melting, can cause the fin 32, but this generally does not have any major negative effects on the actual copper base body.

In order for the ribs 32 to be sufficiently effective, they must have certain minimum dimensions. In the embodiment shown, the ratio of the height "H" of the ribs 32 to the thickness "S" of the copper lining between the ribs 32 is, for example, approximately 2: 3. This ratio should normally be between 1: 2 and 1: 1. The ratio of the width "B" of the ribs to the width "N" of the grooves 34 and the ratio of the height "H" of the ribs to the width "B" of the ribs should both be between 1: 3 and 3: 1 (in In the embodiment shown, this ratio is approximately 5: 6). The ratio of thickness "S" of the copper lining between the ribs 32 to the average total thickness "F" of the refractory lining 16 + 18 should be between 1:10 and 2: 5 when the tapping channel is new. In FIG. 1, this ratio is 1: 3 in the region of the side plates and approximately 3:10 in the region of the base plates.

In the embodiment according to FIG. 1, the cooling device of the lining 20 comprises cooling channels 36, which are arranged both in the side plates 22, 24 and in the base plate 26. These cooling channels 36 advantageously extend under the ribs 32 through the solid body of the plates 22, 24, 26. In other words, the solid ribs 32 cover and protect the cooling channels 36. A coolant supply (not shown) supplies the cooling channels 36 with a liquid coolant. This coolant supply is advantageously a low pressure cooling water supply, i.e. the feed pressure of the cooling water should preferably be less than 1 bar. If cracks form in the copper plates, the low feed pressure of the cooling water does not cause any major leaks, which reduces the risk of explosion. Coolant supply and cooling channels 36 are preferably designed such that the temperature of the copper lining does not exceed 100 ° C. at any point.

The tapping channel of Figure 1 is made as follows. First, the copper plates 22, 24, 26 are arranged in the support trough 10 and, if necessary, fastened. A first refractory mass is then poured into the copper trough 20, which forms the permanent lining 18. This first refractory mass penetrates into the grooves 34 and completely fills the latter. A box-shaped first casing forms the later boundary layer 38 to the wear lining 16 above the ribs 32. After the first refractory mass has hardened and after the first casing has been removed, the wear lining 16 is produced. For this purpose, a second refractory mass is poured onto the finished permanent lining 18, a second casing forming the channel 12. All copper plates for the tapping troughs of Figures 1 to 5 are advantageously continuously cast. When the copper plates 22, 24, 26 for the tapping troughs in FIG. 1 are continuously cast, inserts in the continuous casting channel can produce through-channels in the casting direction which form the cooling channels 36 in the finished copper plate 22, 24, 26. These through-channels can advantageously have an elongated, for example oval, cross-section, as indicated, for example, in FIG. 2, in the copper plate 124. As a result, the free cross section of the cooling channels 36 'is increased without the material thickness of the copper plate decreasing in the region of the cooling channels 36'. The ribs 32 can also be produced during continuous casting. For this purpose, the continuous casting mold in the continuous casting channel then has corresponding crenellations, which form the grooves 34. Of course, the cooling channels 36 can also be drilled, and / or the grooves 34 can be milled into a forged or rolled copper block. However, continuously cast copper plates 22, 24, 26 with cast-in cooling channels can be produced extremely inexpensively with relatively long lengths. It should be noted that copper plates of great length require fewer coolant connections, which are destroyed if the tapping overflow occurs and could therefore cause an explosion. The tapping gutter of Figure 2 differs from the tapping gutter of

Figure 1 essentially by the following features. The bottom plate 126 has no ribs. It is covered with graphite plates 128, which prevent the iron melt from breaking down. Another difference is that the copper lining 120 has no cooling channels in the corner region 121, 122 between the base plate 126 and the side plates 122, 124. These corner regions 121, 122 are therefore cooled exclusively by the base plate 126 and the side plates 122, 124. In fact, practice has shown that major breakthroughs of the molten iron always take place in these two corner areas 121, 122. Since larger breakthroughs cannot be made to solidify in the refractory lining, there is a risk of the cooling liquid coming into contact with the cooling channel in this area Iron smelt greatly reduced. In other words, a preferred "path" is built into the tapping channel, through which the molten iron can flow out of the tapping channel in the event of larger breakthroughs without coming into contact with the coolant. Regarding the explanations of Figures 1 and 2, it should be noted that the

Base plates 26, 126 can optionally also be designed without cooling channels. In this case, the bottom plates 26, 126 are cooled by heat conduction from the side plates 22, 24, 122, 124. If the iron melt breaks through in the bottom area, the risk of the cooling liquid coming into contact with the iron melt is greatly reduced.

The tapping troughs of FIGS. 3 to 5 differ from the tapping trough of FIG. 1 mainly in that the cooling device of the copper lining 220, 320, 420 each has an external cooling circuit with a liquid coolant, which is located behind the back of the copper lining 220, 320, 420 ( that is, the surface facing the support trough 10) is arranged. In other words, when the molten iron breaks into the permanent lining 18, the copper lining forms a solid protective shield in front of the outer cooling circuit.

In FIG. 3, the outer cooling circuit comprises a spray device 240, which sprays a cooling liquid from pipes 242 by means of spray nozzles 244 onto the rear side of the copper side plates 222 and 224. The cooling liquid running off the surface of the copper side plates 222 and 224 is collected in collecting channels 246. Furrows 248 in the back of the copper side plates 222 and 224 increase the cooled surface and thus the effect of the cooling. It should be noted that it is advantageous to spray an air / water mixture in such a way that most of the water evaporates on the surface.

In FIGS. 4 and 5, the outer cooling circuit comprises outer cooling elements through which a cooling liquid flows and which are attached to the back of the copper lining in a thermally conductive manner. In FIG. 4, these cooling elements are designed as solid bars 340, which are cast, for example, on the copper lining 320, or are welded or soldered to it. Each of these outer cooling beams 340 has at least one internal cooling channel 342. If the cooling beams 340 are only welded or soldered to the back of the copper lining 320, it can be expected that they will detach from the copper lining 320 if the molten iron breaks into the permanent lining 18. This may save them from being destroyed.

In FIG. 5, the cooling elements mentioned are designed as swirl chambers 440 which are arranged vertically on the back of the copper lining 420. Each of these swirl chambers 440 comprises an outer pipe socket 442, an inner pipe socket 444, as well as an inlet line 446 and a return line 448 for a cooling liquid. The outer pipe socket 442 is attached with an open end to the back of the copper liner 420, e.g. welded on. A blind bore 441 can enlarge the chamber 443 formed in the outer pipe socket 442 into the copper plate. Through the closed second end of this outer pipe socket 442, the inner pipe socket 444 is inserted into the chamber 443. Here it forms a central nozzle 450 in the immediate vicinity of the surface of the copper lining 420. The coolant flows through the inlet line 446 into the inner pipe socket 444 and is sprayed from the nozzle onto the surface of the copper lining 420. This creates strong swirls in the chamber 443, which intensify the heat exchange. The swirls in chamber 443 can of course be increased by inserts. The coolant leaves the chamber 443 via the return line 448.

A further advantage of the ribs 32 is finally explained on the basis of the diagram in FIG. 6. This diagram shows the temperature profile in the cross section of a tapping gutter, which is shown under the abscissa axis X. One recognizes the channel with the iron melt 14 hot at 1500 ° C., the wear lining 16, the permanent lining 18, and a copper lining 20 ′. The temperature curve 50 drawn with a solid line shows the Temperature profile for a copper lining with ribs 32. The temperature curve drawn with a dashed line 52 shows the temperature profile for a copper lining without ribs 32, at the same temperature (50 ° C.) and the same thickness of the base body of the copper lining 20 '. The 250 ° C line was drawn into the diagram with an axis line. Above this temperature of 250 ° C, it can be expected that the copper will lose a lot of mechanical strength. As can be seen from the diagram, the distance between the 250 ° C isotherm and the surface 54 of the solid base body made of copper is far greater with a copper lining with ribs 32 than with a copper lining without ribs 32 (compare the distances D1 and D2 in Diagram). In other words, the ribs 32 provide additional security against overheating of the solid base body made of copper, if the thickness of the wear layer 16 decreases over time, and thereby the 1500 ° C. isotherm comes closer to the copper lining.

Claims

claims 1) A molten iron trough comprising: an outer support structure (10); a refractory lining (16, 18) in the support structure (10), a channel (12) for the molten iron (14) being formed in this refractory lining; a copper liner (20, 120, 220, 320, 420) surrounding the refractory liner (18) in the support structure (10); and a cooling device for forcibly cooling the copper liner (20, 120, 220, 320, 420); characterized by massive ribs (32) on the copper lining (20, 120, 220, 320, 420) which protrude into the refractory lining (18). 2) tapping gutter according to claim 1, characterized in that the refractory lining comprises a wear lining (16) and a permanent lining (18), the ribs (32) extending substantially up to half the thickness of the permanent lining (18). 3) tapping gutter according to claim 1 or 2, characterized in that the refractory lining (18), at least in the region of the ribs, is poured onto the copper lining. 4) tapping trough according to claim 1, 2 or 3, characterized in that the copper lining (20, 120, 220, 320, 420) is formed by solid copper plates (22, 24, 26). 5) tapping gutter according to claim 4, characterized by a base plate (26) and two side plates (22, 24) made of copper. 6) tapping trough according to claim 5, characterized in that the bottom plate (26) with graphite plates (128) is covered. 7) tapping gutter according to claim 5 or 6, characterized in that the copper lining (120) between the base plate (26) and side plates (22, 24) each have a corner region (121, 126), the copper lining (120) except for this corner region is directly cooled with a liquid coolant. 8) tapping gutter according to one of claims 1 to 7, characterized in that the ratio: height "H" of the ribs (32) to thickness "S" of the copper lining (20, 120, 220, 320, 420) in the grooves (34 ) between the ribs (32), between 1: 2 and 1: 1. 9) tapping trough according to one of claims 1 to 8, characterized in that the ratio: width "B" of the ribs (32) to width "N" of the grooves (34) between the ribs (32); and the ratio: height "H" of the ribs (32) to width "B" of the ribs (32); is between 1: 3 and 3: 1. 10) tapping gutter according to one of claims 1 to 9, characterized in that the cooling device comprises cooling channels (36) in the copper lining (20), each of the cooling channels (36) being covered by a rib (32). 11) tapping trough according to claim 10, characterized in that the ribs (32) and cooling channels (36) run parallel to the longitudinal direction of the tapping trough. 12) tapping trough according to claim 11, characterized in that the copper lining (20) is formed by continuously cast copper plates (22, 24, 26), wherein cooling channels (36) are formed as continuous channels in the casting direction during continuous casting. 13) tapping trough according to claim 11 or 12, characterized in that the ribs (32) are formed during the continuous casting by battlements in a continuous casting mold. 14) tapping trough according to one of claims 1 to 9, characterized in that the cooling device an external cooling circuit with a liquid Coolant which has the copper liner (220, 320, 420) from the rear, i.e. cools from the support structure (10). 15) tapping trough according to claim 14, characterized in that the external cooling circuit has a spray device (240) which is opposite the back of the copper lining (220). 16) tapping trough according to claim 15, characterized in that the back of the copper lining (220) is enlarged by furrows (248). 17) tapping gutter according to claim 14, characterized in that the cooling circuit comprises a cooling liquid through which external cooling elements (340, 440) are attached to the rear of the copper lining (320, 420) in a thermally conductive manner. 18) tapping trough according to claim 17, characterized in that the cooling elements comprise solid copper beams (340) with integrated cooling channels (342). 19) tapping trough according to claim 18, characterized in that the copper bars (340) are welded or soldered to the back of the copper lining (320). 20) tapping trough according to claim 14, characterized in that the cooling elements comprise swirl chambers (440) for the cooling liquid, which are arranged perpendicular to the back of the copper lining (420). 21) tapping gutter according to claim 20, characterized in that each swirl chamber (440) comprises the following parts: an outer pipe socket (442), which is attached with an open end sealed to the back of the copper lining (420), one closed inner chamber (243) is formed in the outer pipe socket (442); an inner pipe socket (444) sealed into this inner chamber (243) where it forms a nozzle (450) in close proximity to the surface of the copper liner (420); an inlet line (446) for a cooling liquid which opens into the inner pipe socket (444); and a return line (448) for the cooling liquid, which opens into the outer pipe socket (442).