Studs and their installation structures

Abstract

To provide a stud installed at a steel shell upon lining an unshaped refractory to an industrial furnace, the stud being movable following the movement of the unshaped refractory during use, and its installation structure.SOLUTION: A stud 1 installed at a steel shell 6 of an industrial furnace lining an unshaped refractory comprises: a base part 2 having a through hole 21 and fixed to the steel shell 6; and a stud body 3 inserted into the through hole. The stud body 3 has a bend part 31, the bend part is fixed to the base part 2 at a side in contact with the inner face of the through hole 21 by tack welding 5, and a gap is provided between a face other than the side in contact with the inner face of the through hole 21 of the bend part 31 and the inner face of the through hole 21. Adjacent studs 1 are plurally installed at a steel shell of a rotary kiln so as to be rotated by 90 degrees with respect to the central axis of the stud body 3 each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stud and its installation structure that is installed in the steel shell when lining an industrial furnace such as a molten metal container, a waste treatment furnace, a heat treatment furnace, or a rotary kiln with a monolithic refractory material. [Background technology]

[0002] For example, in rotary kilns lined with monolithic refractories such as castable refractories, studs (also called anchors) are generally installed on the steel shell to prevent the monolithic refractory from falling off or peeling off during use. Because the studs are usually welded to the steel shell, they cannot follow the movement of the monolithic refractory that accompanies the expansion and contraction of the monolithic refractory during use, which can lead to cracks in the monolithic refractory, causing it to fall off or peel off.

[0003] As a countermeasure, Patent Document 1 discloses an anchor metal structure consisting of an anchor metal and an anchor metal fixing hardware that fixes it, allowing the anchor metal to move up, down, left, and right. However, in the anchor metal structure of Patent Document 1, the amount of movement of the anchor metal is limited within the range of the gap between the anchor metal and the anchor metal fixing hardware, which limits the movement of the monolithic refractory that accompanies expansion and contraction of the monolithic refractory during use, resulting in insufficient crack suppression effects. Furthermore, if this gap is made larger, the monolithic refractory will fill the gap when lining the monolithic refractory, causing the anchor metal to become unable to move.

[0004] On the other hand, Patent Document 2 discloses an anchor for fireproofing material that consists of a short stud with a horizontal hole and an anchor made by bending a round rod with a diameter slightly smaller than the horizontal hole into a V-shape. The anchor can be inserted into the horizontal hole perpendicular to the stud, and when the anchor is raised, its bent portion is tensioned by the horizontal hole, semi-fixing it. However, in the fireproofing anchor of Patent Document 2, because the anchor is in tension by contacting the top and bottom of the horizontal hole of the stud, a considerable force is required for the anchor to move, and it is not able to follow the movement of the monolithic refractory material sufficiently. Furthermore, even if a large force is applied and the anchor moves, it can only move freely in the direction of rotation about the horizontal hole as a central axis, and movement in other directions is difficult, so it is not very effective in suppressing cracks that occur in the monolithic refractory material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-136155 [Patent Document 2] Jikko No. 53-49065 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that this invention aims to solve is to provide studs that are installed on the steel shell when lining an industrial furnace with monolithic refractory, and an installation structure for the studs that can move to follow the movement of the monolithic refractory during use. [Means for solving the problem]

[0007] The gist of the present invention is as follows. 1. A stud to be installed in the steel shell of an industrial furnace lined with monolithic refractories, a base portion having a through hole and fixed to the shell; a stud body that is inserted into the through hole, The stud body has a bent portion, and the bent portion is fixed to the base portion by tack welding on the side that contacts the inner surface of the through hole, A stud having a gap between the inner surface of the through hole and a surface of the bent portion other than the side that contacts the inner surface of the through hole. 2. 2. The stud according to 1 above, wherein the bent portion is fixed by tack welding only on one of the two opening surfaces of the through hole in the base portion. 3. 3. The stud according to claim 1 or 2, wherein the stud body is V-shaped with a bent portion. 4. 4. The stud according to any one of claims 1 to 3, which is installed in the steel shell of a rotary kiln lined with monolithic refractory material. 5. A stud installation structure comprising a plurality of studs according to any one of 1 to 3 installed on the iron shell of a rotary kiln lined with monolithic refractory, A stud installation structure in which adjacent studs are installed at a 90-degree angle relative to the central axis of the stud body. [Effects of the Invention]

[0008] According to the present invention, the occurrence of cracks in the monolithic refractory during use can be suppressed, and therefore peeling and falling off of the monolithic refractory can be suppressed, thereby improving the life of the industrial furnace. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of a stud according to an embodiment of the present invention. [Figure 2] Side view of the stud in Figure 1. [Figure 3] Plan view of the stud in Figure 1. [Figure 4] Plan view (developed view) of multiple studs in Figure 1 installed on the steel shell. DETAILED DESCRIPTION OF THE INVENTION

[0010] Fig. 1 shows a vertical cross section of a stud 1 according to one embodiment of the present invention, Fig. 2 shows the stud 1 in a side view, and Fig. 3 shows the stud 1 in a plan view. The stud 1 includes a base portion 2 having a through hole 21 and fixed to the shell 6, and a stud body 3 inserted into the through hole 21.

[0011] The base portion 2 has a rectangular parallelepiped shape and has a through-hole 21 with a circular cross section that penetrates perpendicularly to two opening surfaces 22A and 22B that are its side surfaces. The installation surface 23, which is the bottom surface of the base portion 2, is securely abutted against the steel shell 6 and is fixed to the steel shell 6 by welding (this weld is indicated by the reference numeral 4 in Figures 1 and 2). The dimensions of the base portion 2 are 50 mm in height, 60 mm in width, and 16 mm in thickness, and the inner diameter of the through-hole 21 is 25 mm. To facilitate welding, grooves are provided on the installation surface 23 side of the two opening surfaces 22A and 22B.

[0012] The stud body 3 is V-shaped with a bent portion 31, and is inserted through the through hole 21 of the base portion 2 so that it is approximately perpendicular to the installation surface 23 of the base portion 2. Specifically, the bent portion 31 of the stud body 31 is fixed by tack welding to the opening surface 22A of the base portion 2 on the side that contacts the inner surface of the through hole 21. A gap (space) is secured between the inner surface of the through hole 21 and the surface of the bent portion 31 other than the side that contacts the inner surface of the through hole 21. The stud body 3 is made from a round steel bar with a diameter of 16 mm that has been machined into a V-shape with a bent portion 31, and the inside of the bent portion 31 has an R20 radius. The length of the stud body 3 is 200 mm. The maximum length L (see Figure 2) of the gap between the stud body 2 and the inner surface of the through hole 21 is 7 mm. In order to facilitate insertion of the stud body 3 into the through hole 21 and to facilitate tack welding, the upper sides of the two opening surfaces 22A, 22B of the through hole 21 are each machined to have an arc shape.

[0013] As clearly shown in Figure 3, the stud body 3 is fixed by tack welding at the bent portion 31 only on the side of one of the two opening surfaces 22A, 22B of the base portion 2, namely, the opening surface 22A. This tack weld 5 has a weld length of 15 mm and a weld leg length of 5 mm. Here, tack welding is not a permanent weld, but rather a weld used to temporarily hold the stud body 3 in a set position. For example, the size of the tack weld can be 5 to 18 mm in weld length and 3 to 10 mm in weld leg length.

[0014] The stud 1 can be assembled and installed by either welding the base portion 2 to the steel shell 6 and then tack-welding the stud body 3 to the base portion 2, or by tack-welding the base portion 2 and the stud body 3 and then welding the base portion 2 to the steel shell 6.

[0015] In this embodiment, tack welding is performed between the stud body 3 and the opening surface 22A of the base portion 2, but tack welding may also be performed at a total of two locations, between the two opening surfaces 22A and 22B. Fixing the stud body 3 by tack welding only on one of the opening surfaces, as in this embodiment, has the advantage of increasing the efficiency of the work of attaching the stud body 3 to the base portion 2.

[0016] Tack welding can be performed at any position on the side where the bent portion 31 of the stud body 3 contacts the inner surface of the through hole 21 of the base portion 2. It is believed that during use, the monolithic refractory moves in multiple directions relative to the steel shell 6 due to expansion and contraction, and the tack welded portion 5 is thought to come off when the monolithic refractory moves in one of the directions at an early stage immediately after installation, and is therefore not affected by the position of the tack weld.

[0017] When the tack weld 5 comes off during use, the stud body 3 can move to some extent in any direction, and the monolithic refractory can move in any direction relative to the steel shell 6. This prevents the monolithic refractory from peeling off or falling off. When the tack weld 5 comes off, the stud body 3 becomes movable within the through hole 21, but it does not come off the base portion 2, so the monolithic refractory will not fall off the steel shell 6.

[0018] The size of the base portion 2 is not particularly limited, but if it is too large, the welding process will be more time-consuming, so it is fine as long as it is large enough so that it does not come off the steel shell 6 during use. Regarding the diameter of the through hole 21 in the base portion 2, it is sufficient to ensure that the maximum length L (see Figure 2) of the gap between the stud body 2 and the inner surface of the through hole 21 is 3 mm or more. If the length of the through hole 21 is too long, the radius (R) of the bent portion 31 of the stud body 3 will become large, and there is also the risk that monolithic refractory material that has entered the through hole 21 will hinder the movement of the stud body 3. Therefore, it is better to make it short, taking into consideration the type of furnace, operating temperature, workability, weld strength, stud size, etc. Specifically, it can be 5 to 25 mm.

[0019] The stud body 3 needs to have a bent portion 31 to prevent it from coming off the base portion 2, and can be V-shaped, U-shaped, J-shaped, etc. In particular, by making the stud body 3 V-shaped with the bent portion 31, the effect of preventing the monolithic refractory from falling off is greater.

[0020] By installing the stud 1 of this embodiment in the steel shell of a rotary kiln lined with monolithic refractory, a significant effect of preventing the monolithic refractory from falling off or peeling off can be obtained. Because the monolithic refractory rotates in a rotary kiln, unlike other industrial furnaces, the monolithic refractory experiences large stress in the direction of rotation around the rotary kiln's rotation axis, and because of the rotation, stress also changes direction. The stud 1 of this embodiment can tolerate some movement of the monolithic refractory in response to this stress, so by alleviating the stress, it is possible to prevent the monolithic refractory from falling off or peeling off.

[0021] Furthermore, when installing the studs 1 of this embodiment in the steel shell of a rotary kiln, it is preferable to install adjacent studs rotated 90 degrees relative to the central axis of the stud body 3, as shown in FIG. 4. This installation structure allows the monolithic refractory to move more easily relative to the steel shell, thereby alleviating stress and more effectively preventing the monolithic refractory from falling off or peeling off. Here, the central axis of the stud body 3 is the longitudinal central axis C of the stud body, as shown in FIG. 1. Furthermore, by setting the spacing (pitch) between adjacent studs 1 to 150 mm to 250 mm, the effect of preventing the monolithic refractory from falling off can be sufficiently obtained. Note that the spacing (pitch) between adjacent studs refers to the spacing between the center points of the bases of adjacent studs. [Example]

[0022] The studs 1 shown in Figures 1 to 3 were installed on the steel shell of a rotary kiln at intervals (pitch) of approximately 200 mm in the pattern shown in Figure 4, and monolithic refractory (alumina castable) was poured into it to a thickness of approximately 300 mm over a 10 m length. This resulted in a 20% improvement in lifespan compared to the conventional example in which V-shaped studs were welded directly to the steel shell. Note that in the case of a rotary kiln steel shell, the pattern in Figure 4 is shown in a developed view. [Explanation of symbols]

[0023] 1 stud 2 Base 21 Through hole 22A,22B opening surface 23 Installation surface 3 Stud body 31 Bend 4 Welded parts 5 Tack welds 6 Ironhide

Claims

1. A stud to be installed in the steel shell of an industrial furnace lined with monolithic refractories, a base portion having a through hole and fixed to the shell; a stud body that is inserted into the through hole, The stud body has a bent portion, and the bent portion is fixed to the base portion by tack welding on the side that contacts the inner surface of the through hole, A stud having a gap between the inner surface of the through hole and a surface of the bent portion other than the side that contacts the inner surface of the through hole.

2. 2. The stud according to claim 1, wherein the bent portion is fixed by tack welding only on one of two opening faces of the through hole in the base portion.

3. 3. A stud according to claim 1 or claim 2, wherein the stud body is V-shaped with a bent portion.

4. The stud according to any one of claims 1 to 3, which is installed in the steel shell of a rotary kiln lined with monolithic refractory material.

5. A stud installation structure comprising a plurality of studs according to any one of claims 1 to 3 installed on the iron shell of a rotary kiln lined with monolithic refractory, A stud installation structure in which adjacent studs are installed rotated 90 degrees relative to the central axis of the stud body.

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