EP0151970B1 - Installation process for a converter bottom - Google Patents

Description

The invention relates to a method for installing a converter floor, in particular one which has inlet nozzles for media and in which the largest area with floor stones of commercially available stone formats is delivered on a floor plate.

In the case of vessels for holding a molten metal, in particular an iron melt, in which there are nozzles in the bottom of the vessel for introducing various media into the molten metal, it is known that there is greater wear of the refractory base stones compared to the vessel lining. For this reason, for example, bottom-blowing steel production converters or iron bath reactors for gas generation and corresponding converters for melting reduction have exchangeable vessel bottoms. These treatment vessels, here generally referred to as converters, have a removable base plate on which the floor lining is located. The inlet nozzles are built into this fireproof floor delivery, and if necessary, usually when the refractory material has worn down to the safety layer, the floor is replaced with a new one. The space that remains free during floor installation, i.e. H. the adjustment joint between the floor and vessel masonry is filled with a refractory mass. When the entire converter is relined, this mass is stamped in, and when the floor is changed in the heated vessel, the joint is filled with a pourable mass. In particular, tar or pitch-bound products based on magnesite and / or dolomite have proven themselves as refractory materials for this application.

Under favorable operating conditions, a steelmaking converter that is only operated with floor nozzles or combined blowing technology requires at least one floor change during the converter journey. In a first approximation, wear rates are about twice as high compared to wall masonry.

The absolute wear of the refractory material, for example in a steel production converter, depends on the operating conditions, in particular on the maximum temperature, usually the tapping temperature of the molten steel. For the preferably used pitch-bound, low-iron magnesite stones, wear rates of 0.3 to 0.6 mm per batch result for the vessel lining at an average tapping temperature of 1,600 ° C, while a wear rate of at an average tapping temperature of 1,680 ° C approx. 1.6 mm occurs per batch. As already mentioned, the wear of the floor stones is higher by a factor of 2.

With increasing stress on the vascular lining, d. H. with increasing operating temperatures of the converters, there is still disproportionate wear of the adjustment joint between the bottom of the vessel and the wall lining provided with ramming or casting compound. Repairs are required to counteract the premature wear in this area. For this purpose, similar to when changing the floor in a hot container, the pre-worn joint is cast with a pitch-bound compound. Just like changing the floor itself, these repair measures, with the subsequent heating and sintering in of the casting compound, have a negative effect on the converter availability. In addition, the wear on the joints has an unfavorable effect on the floor durability, since the floor curbs round off towards the joint and wear out faster than the floor center.

Efforts to improve soil durability have not been lacking in the past. For example, German Offenlegungsschrift 2,843,735 describes a floor in which only one nozzle is arranged per row of stones. Stronger joints up to 2.5% of the maximum stone width in the floor masonry are also recommended. However, according to the teachings of this application, floors have not been able to bring the wear rates of the floor stones into the order of magnitude of the converter delivery in which these floors are installed.

German patent specification 2,654,232 relates to a method and a device for producing nozzle bases for oxygen blow-through converters with jacket gas nozzles, in which the channels for the nozzles are drilled after the stones have been built onto the base plate. This method allows the floor stones to be walled up on older, partly discarded floor slabs with tight joints, regardless of the shaped stones for the nozzles. However, with the floors produced according to this method, the problem of the pre-wearing adaptation joint between the floor masonry and the converter delivery remains, since the exchangeable floors can only be installed after the converter lining has been completed.

The invention has for its object, while maintaining the advantages of the floor infeed, to connect it to the wall infeed of a converter so that the leading wear in the joint between the floor and wall lining is avoided, the durability of the floors is increased and thus the converter availability through Elimination of repair times is improved.

The solution to this problem is that after the floor has been inserted into the converter, the edge region of the floor plate that remains free of the floor stones is delivered with shaped stones to the converter lining and between these shaped stones and the floor stones dimensionally accurate fitting stones are used.

Shaped stones of such a geometry are preferably used that a rectangular free space is formed between them and the adjacent floor stones, based on the floor level. The side of the shaped stones facing the ground stones is preferably flat. Rectangular stones are preferably used as floor stones.

The space that remains between the molded block and the adjacent floor block is wider than the desired joint width. The joint widths are preferably between 0.5 and 3 mm and in particular about 1 mm. The width of the free space between the shaped stone and the adjacent floor stone is preferably more than 5 mm, in particular more than 10 mm, and is usually in the range from 20 to 150 mm.

The dimensions for the fitting stones are preferably taken at two or even several different heights, since it has been shown that the width of the free spaces fluctuates in height. The fit stones can be composed of several parts. It is therefore possible to provide several narrow fitting stones to fill in the free space. The fit stones and the shaped stones are preferably installed with mortar.

The shaped blocks are adapted on the side of the curvature of the converter lining facing the converter lining. "Adapted does not mean" exactly adapted ", but only approximates. This is preferably achieved in that the side facing the converter lining is flat, but the shaped stone is cut and laid out in such a way that both edges of the side facing the converter lining come to rest on the lining, whereby this side lies as a chord for lining. Such an adjustment can be achieved with little effort and is generally sufficient. For special embodiments, however, it is possible to adapt the shaped block of the converter lining polygonally or by rounding it down even more.

The base plate with the refractory lining is preferably first mechanically attached to the converter in a known manner. The space between the floor stones and the converter lining, hereinafter referred to as the free edge area, adjustment joint or seal, is after this frictional installation of the base plate on the converter up to the level of the floor wear stones, d. H. in addition to the soil safety lining, as usual with a refractory material. and then the installation of the shaped and fitting stones begins. The refractory mass in the seal can also be up to a greater height, i. H. partly also stamped next to the floor wear stones. The shaped and fitting stones are then correspondingly shorter and, for example, only installed in the upper half of the adjustment joint. However, the length of the shaped and fitting stones preferably corresponds to the height of the floor wear stones.

The shaped stones are placed against the cylindrical vessel lining in this area in such a way that a rectangular cross section preferably remains free between the shaped stone and the closest floor stone. The fitting stone is then inserted into this space. The fitting stone can be assembled from two or more prefabricated stone slabs, prefabricated in different wall thicknesses, and the space between them can be installed.

With this type of infeed according to the invention, there is no need for a precise cutting of the fitting stone. In practice, however, it has been shown that due to wall inaccuracies in the delivery of soil and vessels, this space between the form and floor stone mostly deviates from the rectangular cross-section, both in height and perpendicular to it. Therefore, the preferred implementation of the method according to the invention is to measure the space mentioned from the shaped stone to the floor stone and to install a dimensionally cut fitting stone. The dimensions can be determined in several heights on both sides of the space. These dimensions are preferably taken at two heights, near the upper and lower ends of the shaped block or the intermediate space. The fitting stone is then cut according to the determined dimensions of the space, preferably as a whole or lengthwise from two, or in special cases several pieces with conventional cutting discs or diamond saws and then installed.

If the space at the bottom is wider than at the top, then a first fitting stone is preferably used, which is shaped so that a uniformly wide space remains after insertion of the same. The first key is wider at the bottom than at the top. A second fitting stone is then inserted into the remaining, uniformly wide space.

The adjustment joint with shaped and fitting stones is preferably delivered in rows, for example in an extension of the rows of floor stones and / or perpendicularly thereto. First the shaped stones are fixed to the wall, the dimensions for the fitting stone are determined and then the fitting stone is used as a whole or in two or more parts. The blocks can be fixed to the essentially cylindrical wall lining by adhesive or refractory mortar or by mechanical clamping and / or holding devices between the block and the floor block. For example, wedges, compression springs and simple spreading devices have proven themselves as clamping and holding devices. After installing the shaped blocks with the mentioned clamping and / or holding devices, the dimensions of the intermediate space are determined and the fitting block is cut accordingly to. The clamping and / or holding device is then removed and the fitting stone cut to size. The fitting stones can be laid dry without a joint filler, but they are preferably installed using commercially available mortars.

Another feature of the invention is the total joint space in the walls of the floors; which are installed in the converter according to the method of the invention. The sum of the joint thickness between the floor, form and fit stones, based on these stone dimensions, should be on average between 0.5 to 1.2%. An almost even distribution of these joints in the masonry is desirable. As a result, the joint width, with or without mortar or adhesive filling, in the direction of the stone rows in which, for example, the stones are 100 mm wide, is on average 0.5 to 1.2 mm. Individual joints up to a width of approx. 3 mm can be tolerated.

According to the invention, the converter floors can be made from one or more refractory stone qualities. It has proven useful, for example, to build the majority of the converter base from low-iron, pitch-bonded magnesite stones and to use high-carbon magnesia qualities with a high proportion of molten sinter in the vicinity of the nozzles. For example, 50% to 90%, preferably 60% to 80%, of the entire floor area is supplied with commercially available pitch or synthetic resin-bonded magnesite stones made of low-iron sintering up to dead sea periclase and a residual carbon content of approximately 4 to 6%. In the vicinity of the nozzle, i.e. H. At least 50 mm around the outer nozzle tube, special stone qualities with an increased carbon content are used. These special stones. can consist of a mixture of at least 50% magnesite melting grain and pure magnesite sinter up to 100% melting grain. The carbon is added in the form of graphite, for example natural flake graphite. The residual carbon content of these magnesite carbon stones is between 10 to 25%, preferably 12 to 18%. The binding is made of pitch and / or synthetic resin.

Surprisingly, the converter trays installed by the method according to the invention have a considerably better durability than comparable trays used in a known manner. The method according to the invention makes it possible for the first time to reliably achieve the same durability as the converter lining with floors which have inlet nozzles for media, in particular oxygen inlet nozzles with a hydrocarbon coating. So there is no need to change the floor during the converter journey. This results in an increase in converter availability, which is associated with advantages for operational practice, for example by increasing productivity in a steel mill, and improves profitability.

A further, clear advantage of the method according to the invention over the known solutions is the wear characteristic of the refractory inlays. The wear profile is relatively uniform and, in particular, no longer has any leading areas that require repair. In this way, the disadvantage of the known methods for installing the converter floors, which show excessive wear in the area of the adjustment joint provided with refractory masses, was completely overcome. For example, in the case of a ground-blowing steel production converter with an average operating temperature of 1,670 ° C., the known seal, supplied with a pitch-bonded magnesite mass, had to be repaired three to ten times during a ground journey. 6 to 25 hours of operating time are lost, and the consumption of refractory repair compound is up to 20 t. When using the method according to the invention for installing the converter floors, there are no longer any production downtimes for repairing the floor seal, and the repair mass is also saved.

• Die Zeichnungen zeigen in Figur 1 einen waagerechten Schnitt durch Teilbereiche der Boden-und Konverterwandzustellung mit Form- und Paßsteinen und in Figur 2 ebenfalls einen waagerechten Schnitt durch einen Teilbereich der zuvor genannten Ausmauerung, jedoch mit einer anderen Variante des erfindungsgemäßen Bodeneinbauverfahrens mit Form- und Paßsteinen.

The invention is explained in more detail below with the aid of non-restrictive examples and drawings:

• The drawings show in FIG. 1 a horizontal section through partial areas of the floor and converter wall infeed with shaped and fitting stones, and in FIG. 2 also a horizontal section through a partial area of the aforementioned brick lining, but with another variant of the floor installation method according to the invention with shaped and fitting stones .

On a base plate, not shown, there is a safety lining 150 mm high made of pitch-bound, low-iron magnesite stones. The base stones (1) with an average joint width (2) of 0.7 mm are then bricked up with an organic adhesive mortar that contains approx. 70% magnesite flour as a filler. The floor stones have a rectangular cross-section with the dimensions (3) of 100 mm, (4) of 150 mm and a stone length of 900 mm. The floor delivery, including drilling the nozzle channels and installing the inlet nozzles with the associated piping below the base plate, takes place outside the converter with the base plate standing vertically according to German Patent 26 54 232. After installing the base on the converter, the space (seal) is between the Ground stones (1) and the stones (5) of the converter side wall are leveled with a pitch-bonded magnesite mass up to the level of the safety lining, ie up to the wear stones (1). Then the installation of the shaped blocks (6) begins - indicated by hatching in FIGS. 1 and 2. These shaped stones (6) have an adaptation angle (7) on the side facing the cylindrical wall masonry with the stones (5). The adjustment angle (7) changes from stone layer to stone layer. It is approx. 90 ° in the stone layer that intersects the center of the soil and then decreases in each subsequent layer. However, there is a shaped block (6) with the same adjustment angle (7) for each circular quadrant.

The shaped blocks (6) are fixed according to Figure 1 in the direction of the floor blocks either by wedges (8) and (9) or with at least two compression springs (10) along their entire height on the side wall. The dimensions (11) and (12) are then determined in at least two different heights. The fitting block (13) is cut according to the determined dimensions (11) and (12) and inserted after removing the holding devices (8), (9) or (10). The shaped blocks (6) and the fitting blocks (13) are installed using conventional mortar joints. However, it can also be worked with the appropriate adhesives, similar to the laying of floor tiles, or without a joint filler.

The laying of the shaped stones (6) usually starts next to the middle layer of floor stones and then, following the layers of floor stones, sets the adjacent shaped stone. In order to install the shaped stones (6) and fitting stones (13) in the entire area of the seal in the shortest possible time, an overlapping method of working has proven itself. This can be done, for example, in such a way that the shaped blocks (7) are first installed in the first of the four quadrants, the dimensions (11) and (12) are determined and the cutting of the fitting stones is started. During the cutting time for the fitting stones, the shaped stones (6) can already be placed in the next circular quadrant and the cut fitting stones (13) can be installed in parallel in the first quadrant. The same applies to further delivery.

Figure 2 shows another embodiment of the method according to the invention. The principle of operation is basically the same as that described for FIG. 1, but here the shaped (6) and locating stones (13) are perpendicular to the floor stone layers, formed from the floor stones (1). It is in the spirit of the invention to work with both installation variants of the shaped and fitting stones on the same floor. Of course, the method according to the invention can be used independently of the laying pattern of the floor stones. Figure 1 shows, for example, the bricked floor stones (1) with a layer height (4), in this case 150 mm, while in Figure 2 the same floor stones are arranged rotated by 90 ° with a layer height (3) of 100 mm.

The inventive method for installing the converter floors can be modified in many ways, for. For example, it is independent of the dimensions of the floor stone, and the floor wall can also be adapted to the side wall of the converter with corresponding shaped and fit stones over more than one floor stone layer. Furthermore, the shaped block (6) can be designed with two or more different adaptation angles (7) or have a rounded outer contour in order to achieve an optimal adaptation to the side wall masonry.

According to the invention, the method can be used regardless of the cross-section of the wall, to which the floors are adapted. The wall infeed is usually cylindrical in the area next to the floor. However, other cross-sectional shapes are also possible, e.g. B. oval to rectangle or square. In the special cases of rectangular or square shape of the wall infeed next to the floor, the installation method of the floors according to the invention is simplified. The shaped blocks then have a rectangular cross section and can be replaced by a, usually enlarged, fitting block in special cases, for example if the seal is narrow.

A 60 t KMS converter has 10 floor nozzles and an inflation nozzle in the upper converter cone. The inlet nozzles in the floor are the well-known OBM nozzles made of two concentric pipes, which are built into the refractory material and for their protection hydrocarbons, in this case propane, are passed through the annular gap. Through the central tube of these nozzles, oxygen with and without lime dust loading and carbon-containing fuels, such as finely ground coke, are fed to the molten iron. Nitrogen and argon can be passed into the melt as further media, and air and / or nitrogen flow through the nozzle tubes during the converter idle times. Oxygen is supplied via the inflation lance during the fresh period, and this nozzle can also be operated with air or nitrogen.

The converter is usually delivered with pitch-bound iron-poor magnesite stones. At the average tapping temperature of approx. 1,675 ° C, the wear rates of the infeed in the lower cone are approx. 1.5 mm / batch, in the cylindrical part approx. 1.2 mm / batch and in the hat approx. 1.3 mm / batch. The average converter durability is approx. 500 batches under the conditions mentioned.

The floor is also largely covered with low-iron, pitch-bonded magnesite stones and in the vicinity of the nozzle with magnesite carbon stones, the residual carbon content of which is approx. 13%. In the known, previously used installation method, the adaptation joint or seal is stamped out with a pitch-bonded magnesite mass or, in the case of the second floor, with the same mass, but poured with tar additive. The wear rates for a floor installed in this way are between 2 and 3 mm / batch. Due to the premature wear of the seal, an average of five repairs with a total of about 10 t tardolomite mass per floor trip are required. Two to three trays are used during a converter trip. The total downtime for repairs and changing floors during a converter trip is on average about 1 day.

After the introduction of the method according to the invention for installing the converter floors and using the same floor infeed, the floor wear rate surprisingly decreases to an average of 1.5 mm / batch. Repairs to the seal and changing the floor during the converter trip are not necessary, since only one floor is required per converter trip. The converter availability and the economy increase accordingly. The refractory costs could be drastically reduced with the method according to the invention. All of the floors installed according to the invention had a converter trip.

When coal gasification in an iron bath reactor with and without simultaneous smelting reduction of iron ore, the installation of the trays with the inlet nozzles for the reactants according to the invention also has a very advantageous effect. In particular, since this continuously operated process eliminates annoying repairs to the seal with the necessary inspections.

Claims (11)

1. A method for installing a converter bottom, whereby the largest area of a bottom plate is lined with flagstones of commercial formats, leaving a free edge area, characterized in that after the bottom is inserted into the converter shaped bricks are inserted beside each other in the free edge area adjacent to the converter lining, the side of said shaped bricks facing the converter lining conforming with the curvature of the converter lining and said shaped bricks being of a size such that a free space exceeding one joint width remains between the shaped brick and the adjacent flagstone, and fitted bricks accurate to size are inserted in these free spaces.

2. The method according to claim 1, characterized in that shaped bricks are inserted having a geometry such that a rectangular free space is formed between them and the adjacent flagstones.

3. The method according to either of claims 1 and 2, characterized in that the free spaces into which the fitted bricks are inserted have a width between the fitted brick and the adjacent flagstone of more than 5 mm.

4. The method according to any of claims 1 to 3, characterized in that the joint width is between 0.5 and 3 mm.

5. The method according to any of claims 1 to 4, characterized in that the flagstones are bricked up on the bottom plate before the bottom is inserted into the converter.

6. The method according to any of claims 1 to 5, characterized in that the shaped bricks are fixed at the converter lining with clamping or holding means provided between the flagstones and the shaped bricks.

7. The method according to any of claims 1 to 6, characterized in that the dimensions of the fitted bricks are determined at two different heights.

8. The method according to any of claims 1 to 7, characterized in that the fitted bricks are composed of several parts.

9. The method according to any of claims 1 to 8, characterized in that the sum of the joints between the flagstones, the shaped bricks and the fitted bricks is adjusted to 0.5 % to 1.2 % of the brick dimensions.

10. The method according to any of claims 1 to 9, characterized in that the shaped bricks and fitted bricks are installed in the direction of the rows of flagstones and/or at right angles thereto.

11. The method according to any of claims 1 to 10, characterized in that 50 % to 90 % of the total bottom area is lined with pitch-bound magnesite bricks poor in iron and the vicinity of the introducing nozzles is lined with magnesite carbon bricks.

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