EP0430740B1 - Cooling plates for blast furnaces and cooling system utilizing such cooling plates - Google Patents

Abstract

Cooling plate (20) especially for a blast furnace, in which a coolant fluid is circulated by means of internal tubes (24e), the said cooling plate (20) being in the shape of a "C" whose arms define two continuous horizontal copings (22 and 23) between which a coating member made of refractory material is inserted. A cooling plant employing plates of this type. <IMAGE>

Description

The present invention relates to a cooling plate used in metallurgical units whose walls are subjected to high heat fluxes such as for blast furnaces.

The present invention also relates to a cooling installation using this type of plate.

Modern blast furnaces are increasingly operated at speeds and pressure levels, such that the heat fluxes emitted can be, globally, locally and randomly important, and which it is necessary to capture and ensure their transfer, especially in the display areas, belly, bottom of tank, mid-tank and top of tank. In particular, in the case of self-supporting units, it is essential that the shield does not reach temperature levels or does not undergo temperature variations with the formation of thermomechanical stresses, which can jeopardize its resistance to mechanical resistance.

The heat fluxes emitted in the different zones of the blast furnace must be captured by a heterogeneous system formed by the refractory lining, the cooling element, ie the cooling plate, the shielding, such that the cooling element fills a dual function of energetic cooling of the refractory and of screen for the passage of fluxes towards the shielding.

The use of such cooling plates disposed between the inner wall of the shield and the refractory lining is necessary, because of the variations in heat flows inherent in modern blast furnace operating techniques, these variations being able to be local, rapid and random over time.

In another field of application, the cooling plates can be brought and maintained at a certain temperature to fulfill functions of heating or maintaining body temperature in any particle size form in order to evacuate their water content or bring them at a temperature necessary for their use.

The cooling plates consist of cast iron elements traversed in their mass by a network of tubes in which circulates a cooling flow which is generally water.

These plates are described in particular in FR-A-2 493 871 and FR-A-2 552 105.

These cooling tubes open on one side of the cooling plates and pass through the shield, outside of which they are connected either to each other or to cooling tubes of an adjacent upper or lower plate. The tubes thus connected determine the circulation lines of the fluid rising in a substantially vertical plane along the wall of the blast furnace, these lines being connected to an external circuit for circulation and cooling of the fluid.

The cooling plates must be designed in such a way that they ensure good heat exchange with the cooling fluid and with the refractory lining, while creating a screen for the heat flow propagating from the furnace to the shielding.

In addition, they must withstand thermomechanical deformations and stresses resulting from high heat fluxes, resist abrasion when the refractory lining has partially or completely disappeared and they must be able to be changed easily without having to enter the enclosure of the upper furnace.

However, the known cooling plates do not always fully meet these conditions.

In fact, they do not make it possible to have, for certain sensitive areas of the blast furnace, an even more efficient screen for the passage of heat flows and to irrigate the angular areas of the plates more intensely.

On the other hand, they have imperfections which lead to more or less totally and more or less quickly losing the refractory lining, which has the consequence of bringing the plates into contact with the charge of the blast furnace, after only a few years, without having been able to fully benefit from the physico-chemical qualities of the refractories used by appreciably delaying the moment from which the plates are subjected to more restrictive conditions, the refractory coating having disappeared.

Cooling installations are known, in particular blast furnaces, the cooling plates of which consist of a cast iron element of substantially parallelepiped shape, in which are embedded longitudinal tubes arranged parallel to each other, these tubes opening onto the same main face, respectively in the upper and lower part of the cooling plate, in a protective sheath, one of the original characteristics of which is the embossed shape from the side opposite to that where the cooling tubes open.

The cooling plates are lined with their refractory lining element directly on the steel site during the construction or repair of a blast furnace, which does not allow this operation to be carried out with all the care and quality controls. required.

EP-A-0337 271 discloses a cooling panel for a shaft furnace comprising a cast iron plate in which are embedded cooling pipes opening on one of the main faces of the plate. A thick layer of refractory concrete is applied to the other main face of the plate before mounting it and is molded on said other face of the plate on a profiled structure to improve the bonding of said layer.

Also known in US-A-1 376 617 is a hearth partition of an oven composed of a brick wall embedded in a box composed of a double envelope and in which a volume of water circulates. The box is made up of two parallelepiped boxes assembled one inside the other and having hollow horizontal and vertical peripheral walls.

The subject of the present invention is a cooling installation having greater reliability, still ensuring uniformly and effective the role of screen in the passage of flows from the furnace to the shielding and allowing the refractory lining element to be placed directly in the workshop.

The present invention thus relates to a cooling plate of a blast furnace in which circulates a cooling fluid by means of internal tubes, characterized in that it has the shape of a "C" whose branches define two curbs horizontal lines between which a coating element of refractory material is inserted.

• au moins une des margelles comporte une contredépouille de blocage de l'élément de revêtement en matériau réfractaire.
• L'élément de revêtement en materiau réfractaire est composé de briques réfractaires façonnées,
• l'élément de revêtement en materiau réfractaire est monolithique, réalisé par coulée d'un béton réfractaire dans l'espace délimité par les margelles,
• la brique s'appuyant sur la contredepouille est une brique débloquant l'ensemble des briques de l'élément de revêtement en matériau réfractaire,
• la contredépouille est un cran de retenue de l'élément de revêtement monolithique.
• une margelle comportant la contredépouille est située en partie haute de la plaque de refroidissement,
• chaque margelle comporte une nappe horizontale d'au moins un tube de refroidissement en fonction de son emplacement dans le haut-fourneau,
• chaque margelle comporte sur sa face chaude un insert de profil approprié pour le renforcement de ladite face chaude,
• l'insert est en carbure de silicium.

According to other characteristics of the invention:

• at least one of the copings has a counter-undercut blocking the covering element made of refractory material.
• The covering element of refractory material is composed of shaped refractory bricks,
• the covering element of refractory material is monolithic, produced by pouring refractory concrete into the space delimited by the copings,
• the brick resting on the undercut is a brick unlocking all the bricks of the covering element made of refractory material,
• the undercut is a retaining notch for the monolithic covering element.
• a coping comprising the undercut is located in the upper part of the cooling plate,
• each curb has a horizontal sheet of at least one cooling tube depending on its location in the blast furnace,
• each coping has on its hot face an insert with a profile suitable for reinforcing said hot face,
• the insert is made of silicon carbide.

The present invention also relates to a cooling installation of a blast furnace using cooling plates defined above, said cooling plates being arranged in successive rings superimposed along the inner wall of the upper shield. - furnace and being traversed by internal tubes where a cooling fluid circulates, the inlets and outlets of said internal tubes being located at different levels, the internal tubes of two adjacent plates in a plane vertical being connected together so as to define a network of vertical circulation lines of the fluid, connected to an external circuit, characterized in that the plates of each crown are, relative to the plates of the adjacent crown, offset in a horizontal plane at least one cooling tube so as to form on the major part of the surface of said plates lines of identical length.

• la Fig. 1 est une vue schématique générale. de l'installation de refroidissement adaptée à un haut-fourneau,
• la Fig. 2 est une vue en élévation latérale d'une plaque de refroidissement,
• la Fig. 3 est une vue de la face arrière de la plaque de refroidissement de la Fig. 1,
• la Fig. 4 est une vue de dessus de la plaque de refroidissement de la Fig. 1,
• la Fig. 5 est une vue développée partielle du réseau de lignes de circulation du fluide de refroidissement sur une partie de la circonférence totale du haut fourneau,
• la Fig. 6 est une vue partielle en élévation latérale montrant la fixation de deux plaques de refroidissement sur le blindage du haut-fourneau.

Other characteristics and advantages of the present invention will appear during the description which follows, made with reference to the appended drawings in which:

• Fig. 1 is a general schematic view. the cooling installation adapted to a blast furnace,
• Fig. 2 is a side elevation view of a cooling plate,
• Fig. 3 is a view of the rear face of the cooling plate of FIG. 1,
• Fig. 4 is a top view of the cooling plate of FIG. 1,
• Fig. 5 is a partial developed view of the network of cooling fluid circulation lines over part of the total circumference of the blast furnace,
• Fig. 6 is a partial view in side elevation showing the attachment of two cooling plates to the shield of the blast furnace.

The installation shown in FIG. 1 comprises a blast furnace 1, against the internal wall of which are placed cooling plates of which only the internal conduits have been shown connected to each other, designated by the general reference 2. The cooling plates indeed have internal tubes which open at different levels to the upper and lower parts of the latter, and are connected to the adjacent upper plate and to the plate adjacent immediately lower in a vertical plane, to define a circulation line formed by all of the internal tubes connected together.

A circular supply line 3, surrounding the blast furnace at its bottom, comprises a set of individual supply lines 4 which are respectively connected. at the inputs 5 of the circulation lines 2. A circular return line 6, surrounding the blast furnace at a higher level, also comprises a set of individual return lines 7 connected to the outputs 8 of the circulation lines. This set of vertical circulation lines constitutes a network placed along the shielding of the blast furnace which is connected respectively at its lower part to the supply circular 3 and at the upper part to the return circular 6.

This network of circulation lines is connected at each of its ends by means of the supply circulars 3 and return 6 to an external circuit, not shown.

In Fig.1, there is shown, for the sake of simplification, only a supply circular and a return circular for a circulation line of the refrigerant.

In fact, the coolant, which in the following description will be considered without limitation as being water, is introduced at different levels in the same vertical plane in different rows of the cooling plates.

As shown in Figs 2 to 4, each cooling plate 20 consists of a cast iron element of substantially parallelepiped shape having the shape of a "C" whose central part constitutes the body 21 of the plate and whose two branches define in the upper and lower part a curb 22 and 23 respectively horizontal and continuous.

In the body 21 of the plate 20 are embedded longitudinal tubes 24a, 24b, 24c ... arranged vertically, parallel to each other and. for example five in number (Fig. 3).

On the rear face of the plate 20 open the inlets 25a, 25b, 25c ... and the outlets 26a, 26b, 26c ... cooling tubes 24a, 24b, 24c ...

The inputs 25a, 25b, 25c ... and the outputs 26a, 26b, 26c ... are distributed over three levels so as to define in the body 21 an alternation of short tubes 24a, 24c and 24e and long tubes 24b and 24d.

Each coping 22 and 23 is cooled for example by two transverse tubes 27a, 27b and 28a, 28a, 28b respectively arranged horizontally, the inlets 270a, 270b and 280a, 280b and the outlets 271a, 271b and 281a, 281b open onto the rear face of the cooling plate.

The horizontal tubes 25a, 27b and 28a and 28b allow the angles of the cooling plate 20 to be cooled more intensely, and provide, with all of the longitudinal tubes, homogeneously, the role of a screen in the passage of heat flows, by effective cooling of each of the cooling plates 20 and of all the plates which are adjoining them.

The number of horizontal tubes is a function of the position of the cooling plate 20 in the blast furnace.

The section of the horizontal tubes 27a, 27b, 28a and 28b is such that it is possible, by sufficient circulation speeds, greater than 2 m / s, to capture the flows emitted without requiring large flow rates, or to generate abnormally high pressure drops .

The speed of circulation of the cooling fluid in the vertical tubes 24a, 24b, 24c ... can be adjusted according to a cooling module.

The front face of the plate 20 located between the coping 22 and 23 has an embossing 30 (Fig. 2) whose waves are filled with a good conductive refractory product 31 of small particle size.

The thickness of the coping 22 and 23 is of the order of 200 mm. At least one of the copings, for example the coping 22 in the example shown in FIG. 2, includes an undercut 22a making it possible to block, for example, the bricks 32 in particular made of silicon carbide bonded to the nitride and forming the refractory coating.

The brick 32a resting on the undercut 22a is a key brick blocking all of the refractory bricks.

Thanks to the "C" shape of the cooling plate 20, the bricks 32 can be mounted directly in the workshop during the manufacturing the plates with all the care and quality controls required, which cannot be perfectly applied during the usual period of construction or repairing the refractory walls of blast furnaces on the steel site.

The refractory covering element can be monolithic, for example made of refractory concrete poured between the coping 22 and 23 and in this case the undercut 22a forms a notch for holding said element on the plate 20.

Thus, this new generation of cooling plates makes it possible to obtain better contact between the cast iron and the refractory, a quality assurance of the implementation of the refractories and a saving of time during the operations of construction or repair of blast furnaces.

Each coping 22 and 23 has on its hot face an insert 33, for example made of silicon carbide, in particular of trapezoidal cross section with dovetail, for reinforcing said hot face (FIG. 2).

Referring to Fig. 5, it can be seen that the cooling plates 20 are arranged in successive rings A, B, C ... superimposed along the internal wall of the shield of the blast furnace and the internal tubes 24 of two adjacent plates in a vertical plane are interconnected so as to define a network of vertical circulation lines of the fluid, connected to the external circuit.

As can be seen in Fig. 5, the plates 20 of a crown on two, for example the plates 20 of the crowns B and D, are offset in a horizontal plane, relative to the plates 20 of the adjacent upper ring A and C, of a cooling fluid circulation tube so as to form over the major part of the surface determined by said cooling plates lines 40 of identical lengths.

This definition makes it possible to obtain a uniform distribution of the cooling fluid.

Referring now to FIG. 6 we will describe the fixing of the plates 20 on the shield 41 of the blast furnace.

Each plate 20 is fixed to the shield 41 using, on the one hand, a fixed point 42 for example in the lower part under controlled pressure on continuous seals 43 made of elastomer and insulating filling products 44 and, on the other hand, from a movable point 45 with sealing compensators 46 for example in the upper part of said plate 20 under controlled pressure on discontinuous seals 47 made of elastomer and insulating filling products 44.

Welded washers 48 are provided between the inlets 25 of the tubes 24 and the shield 41 at the fixed points 42, while sliding washers 49 are provided between the outlets 26 of the tubes 24 at the mobile points 45.

These devices allow the relative movement between the plates 20 and the possible change of the latter at the end of the blast furnace campaign, in a very short time without having to penetrate inside of it.

Between two adjacent cooling plates 20 are provided seals 50 which are mounted after placing said plates on the shield 41. These seals 50 are constituted by example of a fibrous putty.

The installation according to the present invention makes it possible to have, for certain sensitive areas of the blast furnace, an even more efficient screen for the passage of heat flow, to irrigate the angular areas of the plates more intensely and to avoid the creation of 'more or less wide interfaces detrimental to heat transfer and conduction phenomenon through the assembly formed by the plates and the refractory wall.

In addition, the particular shape of the cooling plates avoids the separation of the refractory lining from its support on the hot face, which makes it possible to fully benefit from the physicochemical qualities of the refractories.

Claims (12)

1. Cooling plate for a blast furnace in which a cooling fluid circulates by means of inner tubes (24a, 24b, 24c...), characterised in that it has the form of a "C" the arms of which define two continuous horizontal lips (22, 23) between which is inserted a lining element made from refractory material.
2. Cooling plate as claimed in Claim 1, characterised in that at least one of the lips (22, 23) comprises an undercut (22a) for blocking the lining element made from refractory material.
3. Cooling plate as claimed in Claims 1 and 2, characterised in that the lining element made from refractory material is composed of shaped refractory bricks (32).
4. Cooling plate as claimed in Claims 1 and 2, characterised in that the lining element made from refractory material is in a single piece produced by casting a refractory concrete in the space delimited by the lips (22, 23).
5. Cooling plate as claimed in Claims 1 to 3, characterised in that the brick (32a) bearing on the undercut (22a) is a wedge brick blocking the assembly of bricks (32) of the lining element made from refractory material.
6. Cooling plate as claimed in Claims 1, 2 and 4, characterised in that the undercut (22a) is a notch for holding the single-piece lining element.
7. Cooling plate as claimed in Claim 2, characterised in that a lip (22) comprising the undercut (22a) is located in the upper part of the said cooling plate (20).
8. Cooling plate as claimed in Claim 1, characterised in that each lip (22, 23) comprises a horizontal layer of at least one cooling tube (27a, 27b, 28a, 28b) as a function of its location in the blast furnace (1).
9. Cooling plate as claimed in Claim 1, characterised in that each lip (22, 23) has on its hot face an insert (33) of appropriate profile for reinforcement of the said hot face.
10. Cooling plate as claimed in Claim 9, characterised in that the insert (33) is made from silicon carbide.
11. Installation for cooling a blast furnace with the aid of cooling plates as claimed in one of the preceding claims, the said cooling plates (20) being arranged in successive rings superposed along the inner wall of the casing (41) of the blast furnace (1) and having inner tubes (24a, 24b, 24c...) passing through them in which a cooling fluid circulates, the inlets (25a, 25b, 25c...) and the outlets (26a, 26b, 26c...) of the said inner tubes being located at different levels, the inner tubes (24a, 24b, 24c...) of two adjacent plates (20) in a vertical plane being connected to one another in order to create a network of substantially vertical circulation lines (40) for the fluid, connected to an outer circuit, characterised in that the plates (20) of each ring are offset in a horizontal plane by at least one cooling tube with respect to the plates (20) of the adjacent ring in order to form lines (40) of identical lengths over the greater part of the surface of the said plates (20).
12. Installation as claimed in Claim 11, characterised in that each cooling plate (20) is fixed with controlled pressure against the casting (41) of the blast furnace with the aid, on the one hand, of fixed points (42) in the lower part or upper part of the said plate (20) on continuous elastomer joints (43) and insulating packing materials (44) and, on the other hand, of movable points (45) with a sealing compensator (46). in the upper part or in the lower part of the said plate (20) on discontinuous elastomer joints (47) and insulating packing materials (44).

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