EP1233077B1

EP1233077B1 - Apparatus for repairing blast furnace taphole facings

Info

Publication number: EP1233077B1
Application number: EP02380017A
Authority: EP
Inventors: Emilio Martinez De Valverde
Original assignee: Productos Refractarios Asturianos Para La Siderurg IA SA
Current assignee: Productos Refractarios Asturianos Para La Siderurg IA SA
Priority date: 2001-02-15
Filing date: 2002-01-29
Publication date: 2006-04-05
Anticipated expiration: 2022-01-29
Also published as: EP1233077A1; ES2197738B1; ES2197738A1; DE60210357D1

Description

PURPOSE OF THE INVENTION

This invention refers to a new system for repairing the facings of blast furnace tapholes, with which it is possible to lengthen the useful life of the taphole, especially in view of the continuous use of the hot bar technique, furthermore allowing that repairs can be carried out without the need for stopping the installation.

BACKGROUND TO THE INVENTION

As is known, a blast furnace is a vertical reactor that is loaded through its upper part or mouth with a series of minerals and solid fuels, so that with the injection of hot air and additional fuel, gas, coal, etc., a reduction reaction is obtained that gives rise to pig iron, the fundamental prime material for obtaining the different types of steels, foundry products, etc. This reactor is emptied by means of an outlet located in its lower part, called a taphole, with a diameter of the order of 30 to 60 millimetres and with a length generally between 1 and 3 metres, depending on the type of blast furnace, a taphole through which the pig iron and slag leave and that is one of the critical parts in the operation of a blast furnace.
At present and due to continuous greater demands for productivity in these facilities, the working conditions of the refractories forming the taphole are very demanding, because of which investigation has been done to develop products of greater duration, better cost-benefit ratio and greater margin of security in use, avoiding risks both for people and for the installations.
Within the many solutions for the opening and closing of a taphole, two fundamental methods exist, being those of more widespread use, that of drilling of the taphole and that of the hot bar.
In the taphole drilling method a machine similar to a drill of large dimensions is used, that uses as a bit a bar of approximately three meters length that works simultaneously turning and hammering, axially perforated to refrigerate the cutting head, whether with water, compressed air, or nitrogen, etc. For closing the taphole a machine called a taphole stopper gun is used that consists of a hydraulic system with a pressure of up to 400 Kg/cm², that, using a piston and a plunger, injects the taphole material to close the hole made by the bit during the opening.
The hot bar system consists of inserting a solid bar once in the taphole once the material has been injected with the gun and before the material hardens, with the purpose of later taking it out and that the pig iron and the slag come out through the space left by the extraction of this bar. This system has the drawback that the mass of material has to be sufficiently hard to tolerate the pressure of the interior of the blast furnace, up to 4 Kg/cm², to avoid that this material be expelled to the exterior, and sufficiently soft that it allows the bar to enter and afterwards to be withdrawn. Meanwhile the drilling method doesn't have operational problems, but it is a more expensive and less effective system that the hot bar method, because of which there is a tendency to use the most efficient method provided the working conditions of the installation and the material used are adequate.
Due to the variety of blast furnaces existing and to the different working conditions of each of them, traditionally tests were carried out in the same plant until the mass of material was adjusted to what was more or less better adapted to the operation of that furnace, with the consequent variations in the time. This method furthermore involves a series of risks and problems both for the integrity of people that work in the plant and for the actual plant, and they affect the working conditions of the blast furnace.
Due to these problems, the objective is to set a series of parameters, such as:

Opening length (it protects the refractory lining of the interior of the furnace, and it assures a greater duration of the run-out).
Resistance to the pig iron and the slag at temperatures between 1500-1600°C, both from chemical and mechanical attack.
Regularity of run-outs and among them.
Workability of the product (that it can be manipulated or injected as easily as possible).
Respect for the environment (currently the materials that are used in Spain are tar free to assure as far as possible safety and hygiene in their use and respect for environmental standards).

The hot bar system furthermore has the drawback of progressively causing damage to the facing of the blast furnace taphole, a facing on which the taphole stopper gun does the closing and that has the following as its main functions:

To offer a resistant and the most uniform possible surface so that the gun can inject the taphole stopper material. When this doesn't happen and because the taphole stopper material is a plastic material, it loses injection power, because of which the material mass does not compact adequately within the taphole, material is ejected outside, which causes smoke and blockages in the secondary routes, and furthermore it causes degradation of the gun mounting, which may cause it to remain blocked, since it works at pressure and each time it enters further within the taphole. This has serious consequences for the normal working of the blast furnace.
To protect the taphole refrigeration ring and the breastplate of the blast furnace. If the facing is degraded, the risk is run of puncturing the taphole refrigeration ring or "neck" and of perforation of the breastplate that are faults of major importance and that can only be repaired with the stopping of the plant, with the costs that this implies.
To avoid, as much as possible, the escape of the interior gases of the blast furnace. This escape of gases from the interior of the furnace, in which there are sometimes pressures of up to 4 Kg/cm², is what represents the greatest difficulties and risks for the conservation and maintenance of the facing, to which must also be added the fact that molten liquids, at an average temperature of approximately 1500°C, come out.

All what has been previously set out allows us to say that the maintenance and repair operation of the taphole facing of a blast furnace is a difficult task with high risk for the operatives and that often obliges a stoppage of the plant, with the losses and inconveniences, both technical and economic that this implies.
Document DE19755932C refers to a tapping hole plugging machine for metallurgical furnaces that incorporates a plugging gun provided with a pressure cylinder and a plugging piston for pressing the plug material out of a nozzle of the pressure cylinder, the machine further comprising an end piece which is slidable relative to the nozzle and which is pressed on the furnace wall in the tapping hole zone for sealing purposes.

DESCRIPTION OF THE INVENTION

The system that the invention proposes fully and satisfactorily resolves the previously set out difficulties, allowing the repair of the taphole facing at the same time as the operation of its closing and with the help of the classic taphole stopper gun.
This brings with it a series of advantages among which it is necessary to highlight the following:

It is not necessary that any operator work in a harsh zone, with high temperatures, elevated pressures and high risk for his personal integrity.
The facing can be repaired with the plant in operation and as often as necessary.
It protects the critical zone and allows the continuation of production tasks of the blast furnace.
It allows the continuous use of the hot bar technique with the technical and economic advantages arising from it.
It forms an economic and simple system.

For this and more specifically, the system is based on equipping the gun nozzle with a sleeve perfectly adjusted to this nozzle, that forms an axial and frontal extension for it and in whose cavity is housed a ring of refractory material, that in the connecting of the gun to the taphole face fills the existing hollow in this face, caused by wear in the normal use of the taphole, so that this ring, of an external diameter the same as the internal diameter of the sleeve, will adapt a variable position, according to requirements determined by the depth of taphole facing wear.
The sleeve will be equipped with complementary external limit stops, beside its front end, that in the joining of the taphole stopper gun with the face of the taphole, on impacting on it, will cause the retraction of this sleeve with respect to the nozzle, while the latter advances to the taphole and introduces the refractory ring in its wear depression, where it remains definitively fixed to the plugging material of the oft-mentioned furnace taphole.

DESCRIPTION OF THE DRAWINGS

To supplement this description and with the aim of leading to a better understanding of the characteristics of the invention, in accordance with a preferred example of its practical realization, as an integral part of this description it is accompanied by a set of drawings where in an illustrative and non-limiting way, the following have been represented:

Figure 1. - Shows a schematic representation of a side elevation and section of a blast furnace, to whose taphole a stopper gun is attached.
Figure 2. - Shows an enlarged detail of the previous figure, at the level of the furnace taphole, with the taphole stopper gun separated from it and set up in accordance with the system of the invention.
Figure 3.- Shows the same detail as the previous figure in the taphole stopper gun working position.
Figure 4. - Finally, this shows a detail of the taphole at the end of the simultaneous operation of blockage and repair of its facing.

PREFERABLE REALIZATION OF THE INVENTION

In the light of the figures presented and especially of figure 1, it can be seen how, in a blast furnace, the pig iron is set up at a lower level (1), the slag on the fleet (2), above which the mineral load is located (3), specifically at the level of the hot air entry side nozzles (4), so that the pig iron (1) leaves through the taphole (5) when this is opened, falling to the principle channel (6), closing the taphole (5) with the aid of a taphole stopper gun (7) that injects a dense material in the taphole opening, whether to directly block this hole or to participate in the blockage with the assistance of a bar, so that in the first case a later drilling phase becomes necessary for opening, while in the second this opening is carried out by extracting the bar.
In whichever case the action of the gun (7) on the face (8) of the taphole (5) implies an erosion of this face with its progressive deterioration, that requires periodic repair, specifically to refill the space (9) made by this erosion and visible in figure 2.
For this it is planned to equip the nozzle (10) of the gun (7) with a sleeve (11) whose internal diameter coincides with the external diameter of the nozzle (10), so that it fits tightly to it, forming an axial and frontal extension to it, that allows the holding in its interior of a refractory ring (12), that is in turn of the same external diameter as the internal diameter of the sleeve (11) and of axial dimensions adequate to fill the deteriorated opening,(9) of the taphole (5).
In accordance with this set up and when the taphole stopper gun (7) is attached to the taphole (5) in order to proceed with its blocking or closing, the ring (12) allowing the passing of the blocking material through it, reaches the interior of the opening (9) of the taphole where it remains freed by the retraction of the sleeve (11) to which effect this latter has limit stops (13), radial and external, touching against the face (8) of the taphole, as seen especially in figure 3, so that the material supplied by the gun (7) doesn't only block the taphole opening (5) but also fills the gaps established between the deteriorated face of the taphole and the refractory ring (12), the latter remaining fixed and integrated in the taphole, so that the face of the taphole (8) remains automatically ready and in optimum conditions if a ring of adequate size (12) has been used, as shown in figure 4.

Claims

Apparatus for repairing the facings of a blast furnace taphole, that has as its objective the filling with refractive or similar material the deteriorated opening (9) that progressively is formed in the face (8) of the taphole (5), due to the effect of the action of a taphole stopper gun (7) on this facing in the operations for blocking the taphole, said taphole stopper gun (7) being fitted with a nozzle (10), characterized in that it incorporates an axial extension of this nozzle (10) consisting of a sleeve (11), retractile on it and provided with external limit stops (13) designed to act on the face (8) of the taphole (5) causing the immobilization of the sleeve (11) during the end phase of advance of the nozzle (10) of the taphole stopper gun (7), the sleeve (11) holding a refractory ring (12), in a forward position of the sleeve (11) with regard to the nozzle (10), that is introduced by the nozzle (10) in the interior of the opening (9) of the taphole (5), the refractory ring (12) further allowing the passage through it of the material supplied by the gun (7) and remaining integrated in the facing wear hollow (9) of the taphole (5) by the same mass of closing material supplied by the taphole stopper gun (7).
Apparatus to repair the taphole facings of blast furnaces, according to claim 1, characterized in that the sleeve (11) has an internal diameter similar to the external diameter of the nozzle (10) of the taphole stopper gun (7), to slide properly on it, while the refractory ring (12) has, in turn, an external diameter similar to the internal diameter of the sleeve (11), and a variable axial dimension according to the amount of wear of the taphole facing, that is in according with the depth of the wear hollow (9).