JP7633606B2 - Expansion joints - Google Patents

Description

The present invention relates to an expansion joint that is installed in a portion of a piping system through which high-temperature gas flows.

The overall structure of a typical blast furnace is shown diagrammatically in Figure 8, and an enlarged view of a key portion of Figure 8 is shown in Figure 9.

As shown in Figures 8 and 9, multiple tuyere ports 9 are installed along the furring edge below the body of the blast furnace, and hot air of about 1200°C generated in the hot stove 10 passes through the upper hot air main pipe 11, the mixed cooling pipe 12, the lower hot air main pipe 13, and the annular pipe 14, which are lined with refractory material, and is then blown into the blast furnace from each tuyere 9 via the upper bend 15, the expansion pipe 16, the spherical short pipe 17, and the lower bend 18.

Meanwhile, iron ore, coke, and auxiliary materials are charged into the blast furnace from the top, and when they come into contact with hot air (high-temperature reducing gas) blown in from the tuyere 9, the reduction of the iron ore and other materials in the blast furnace is accelerated, and the iron ore is melted to produce pig iron.

Stable operation is one of the most important issues in blast furnace operation. If the blast furnace cannot operate stably, a temporary shutdown may be performed to temporarily stop blowing hot air. One of the causes of such a temporary shutdown is clogging of the tuyere with bricks or other objects.

This occurs when bricks that line the inside of the pipes for insulation purposes fall off in the hot air flow path (hot air stove - mixing chamber - annular pipe - tuyere), and these bricks or their fragments are carried downstream along with the hot air, causing blockages at the tip of the tuyere, which is the narrowest point in the flow path.

To prevent such trouble, it is important to prevent bricks from falling off. Although sufficient measures to prevent bricks from falling off have been taken in the design and construction stages of blast furnaces and their associated equipment in the past, in reality, it was impossible to completely prevent bricks from falling off.

A conventional method for preventing clogging of tuyere etc. due to fallen or flying bricks, etc., is to provide a cylindrical weir 19 at the branching point of the annular pipe 14, which is the branching point to each tuyere 9, as shown in Figure 9, and to prevent the entry of fallen brick pieces 20 by this weir 19.

The conventional method described above was able to reduce the probability of fallen bricks entering the building to a certain extent, but if brick fragments 20 accumulate in front of the weir 19, there is a concern that other brick fragments may climb over the accumulated brick fragments 20 and enter the tuyere 9. Therefore, it is necessary to check the degree of accumulation of brick fragments 20 at the branching part of the annular pipe 14 and remove them. To do this, it is necessary to remove not only the upper bend 15, but also other equipment such as the expansion pipe 16 and the spherical short pipe 17 connected to the upper bend 15, which requires a large workload and is also dangerous work as there is a risk that the weir 19 will fall during the removal work.

As prior art related to expansion joints, for example, the technology disclosed in Patent Document 1 is referred to, but there is no mention of preventing tuyere clogging or blockage of piping systems caused by fallen bricks.

Japanese Patent Application Publication No. 4-228509

The object of the present invention is to propose an expansion joint that can prevent blockage of piping systems and clogging of blast furnace tuyere holes caused by foreign objects such as fallen bricks.

After much research into preventing foreign objects such as fallen bricks from clogging the piping system and clogging the tuyere of the blast furnace, the inventors have come to a solution by focusing on expansion pipes installed in the piping. An expansion pipe is also called an expansion joint, and as exemplified in the above-mentioned Patent Document 1, it is installed in part of the piping system upstream of the tuyere of the blast furnace and has the function of absorbing displacement due to thermal expansion and contraction of the piping.

That is, the present invention provides an expansion joint that is provided in a pipe through which high-temperature gas flows and absorbs displacement accompanying expansion and contraction of the pipe due to thermal effects by its own expansion and contraction,
The expansion joint is characterized in that it comprises a joint body having an internal passage connected to the flow path of the piping and connectable between end faces of the piping, and a porous body is provided in the internal passage of the joint body, the porous body having a plurality of openings formed therein to allow the passage of high-temperature gas flowing through the flow path of the piping.

In the expansion joint having the above configuration, the porous body has a shape that is convex toward the downstream side of the flow path, the porous bodies are arranged in a multi-stage arrangement at intervals along the axis of the joint body, the porous body located at the most upstream side of the internal path among the multi-stage arrangement has an opening size larger than the maximum size of the opening of any of the porous bodies located at the downstream side of the internal path, the joint body has a support portion on its inner wall surface that supports the porous body at at least two points, the porous body has a notch portion that allows the support portion to pass through, at least one of the shapes in a plan view and a side view of the support portion has a tapered shape, the joint body has a cover on the peripheral wall of the joint body The joint body has an opening that can be opened and closed through a porous body, and allows the material captured in the porous body to be removed to the outside. The joint body is divided into at least two parts in a direction intersecting the axis of the joint body and connected to each other through a bellows, and an outer tube is divided into at least two parts in a direction intersecting the axis of the joint body and connected to each other through a bellows, and surrounds the inner tube with a gap between them. The inner tube has an internal path through which the high-temperature gas passes, and the gap forms a flow path for cooling water. The inner tube has a refractory material on its inner wall surface. Furthermore, the piping through which the high-temperature gas passes is an upper bend and a lower bend that connect the tuyere and the annular pipe of the blast furnace.

According to the present invention, bricks flying through the piping can be captured by a porous body installed inside the contraction joint, so there is no blockage of the piping system or clogging of the tuyere of the blast furnace.

In particular, by disposing the expansion joint of the present invention between the upstream piping connected to the annular pipe of the blast furnace and the downstream piping connected to the blowpipe of the tuyere of the blast furnace, and blowing high-temperature gas supplied via the upstream piping, the expansion joint, and the downstream piping into the blast furnace through the tuyere, it is possible to avoid temporary shutdowns of the blast furnace due to clogging of the tuyere with brick fragments. In addition, because the tuyere is often replaced in a blast furnace, brick fragments that are caught in the expansion joint at that time can be easily collected.

1A and 1B are diagrams showing an embodiment of an expansion joint according to the present invention, in which FIG. 1A is a plan view thereof, and FIG. 1B is a cross-sectional view taken along the line A-A of FIG. FIG. 10 is a schematic diagram showing another embodiment of an expansion joint according to the present invention. FIG. 13 is a schematic diagram showing yet another embodiment of the expansion joint according to the present invention. FIG. 10 is a schematic diagram of another embodiment of an expansion joint according to the present invention. 1A and 1B are diagrams showing a schematic diagram of an expansion joint according to another embodiment of the present invention, in which (a) is a plan view thereof, and (b) is a cross-sectional view taken along the line B-B of (a). FIG. 6 is an explanatory diagram of a method for attaching a porous body to the expansion joint shown in FIG. 5 . 1A and 1B are diagrams illustrating a schematic view of another embodiment of an expansion joint according to the present invention, in which (a) is a plan view, and (b) is a cross-sectional view taken along the line CC of (a). FIG. 1 is a diagram showing a schematic diagram of the overall configuration of a blast furnace. FIG. 9 is an enlarged view (partially in cross section) of a main portion of FIG. 8 .

The present invention will now be described in more detail with reference to the drawings.
1(a) and (b) are diagrams showing an embodiment of an expansion joint according to the present invention, where (a) is a plan view and (b) is a cross-sectional view taken along the line A-A of (a).

In Figures 1(a) and (b), reference numeral 1 denotes a fitting body that can be connected to the end faces of the upstream pipe U1 and the downstream pipe U2, respectively. Note that in Figures 1(a) and (b), the high-temperature gas flows from the upstream pipe U1 to the downstream pipe U2 according to the arrow in Figure 1(b), that is, from the top to the bottom of the page.

The joint body 1 is composed of inner pipes 1a, 1b, which are divided into two parts perpendicular to the axis L of the joint body 1 and connected to each other via airtight bellows B1, and outer pipes 1c, 1d, which are divided into two parts perpendicular to the axis L of the joint body 1 and connected to each other via airtight bellows B2 and surround the inner pipes 1a, 1b across a gap M. The bellows B1, B2 expand and contract appropriately to absorb displacement due to expansion and contraction of the pipes U1, U2 due to thermal effects.

The inner pipe 1a and the outer pipe 1c, and the inner pipe 1b and the outer pipe 1d are integrally connected by the flanges F1 and F2 provided at their ends (upper and lower ends), and the pipe U1 located upstream and the pipe U2 located downstream are connected via the flanges F1 and F2 using fastening means such as bolts and nuts. In the illustrated example, the inner pipes 1a and 1b and the outer pipes 1c and 1d are each shown as being divided into two, but they can also be divided into three or more pipes, and are not limited to being divided into two. Note that the expansion joint according to the present invention is shown as being a double pipe structure consisting of the inner pipes 1a and 1b and the outer pipes 1c and 1d, but it can also be applied to an expansion joint of a single pipe structure.

In addition, the reference symbols 2a and 2b in Fig. 1(a) and (b) denote cylindrical refractories provided on the inner wall surfaces of the inner tubes 1a and 1b. The inner space of the refractories 2a and 2b forms an internal path N for passing high-temperature gas (hot air, etc.). A gap E is provided between the end face 2a1 of the refractory 2a of the inner tube 1a and the end face 2b1 of the refractory 2b of the inner tube 1b, and the expansion joint expands and contracts within the range of this gap E.

The reference numeral 3 in Figs. 1(a) and (b) denotes a plate-like porous body arranged in the internal path N and having a plurality of openings formed therein that allow the passage of high-temperature gas (hot air) flowing through the flow paths of the pipes U1 and U2. The porous body 3 may be a metal plate or mesh, such as punched metal, wire mesh, or expanded metal.

Also, reference numeral 4 in Fig. 1(a) and (b) denotes a support part that is integrally provided on the inner wall surface of the inner tube 1a. The upper surface of the support part 4 is the support surface 4a, and the porous body 3 is supported by placing the front side of the edge part 3a of the porous body 3, in the illustrated example, the lower side of the edge part 3a of the porous body 3 in contact with the support surface 4a, preferably by placing it in a state hooked on the mooring part 4b. The support part 4 and the edge part 3a of the porous body 3 are embedded in the refractory material 2a, and the support part 4 can be provided at two opposing positions on the inner wall surface of the inner tube 1a, or at three or more equally spaced positions around the inner wall surface.

In the expansion joint according to the present invention, a porous body 3 is arranged in the internal passage N of the joint body 1, so that brick fragments flying into the pipes U1 and U2 can be captured by the porous body 3, and clogging in the pipe system and at the tuyere can be prevented.

It is preferable to use a heat-resistant metal for the porous body 3, and the type of metal and structure (size of openings, spacing between openings, size of openings and wire diameter if wire mesh is used, etc.) are determined so that the strength is sufficient to withstand the temperature range of hot air or other high-temperature gases, even if brick fragments fly into it.

The size of the openings in the porous body 3 also affects the airflow resistance, so the structure of the porous body 3 is selected taking this into consideration. A specific example of the porous body 3 that can be used under normal blast furnace operating conditions is a wire mesh made of heat-resistant stainless steel (SUS310S), SUH steel, or a heat-resistant alloy, with a wire diameter of about 3 to 20 mm and mesh openings of about 5 to 50 mm. The mesh openings are preferably large enough to prevent foreign objects such as fallen bricks from passing through the wire mesh and blocking the inside of the pipe from the expansion joint to the tip of the tuyere. In addition, the meshes can be layered to form a double structure in order to ensure the strength of the porous body 3.

Figure 2 is a schematic diagram showing another embodiment of an expansion joint according to the present invention. In this example, the porous body 3 has a shape that is recessed toward the flow direction of the high-temperature gas, that is, a shape that is convex toward the downstream side of the flow path through which the high-temperature gas flows.

The shape of the porous body 3 is preferably such that the center of the porous body 3 protrudes toward the downstream side of the flow path through which the high-temperature gas flows, more than the edge 3a of the porous body 3 supported by the support portion 4. This increases the total area of the part through which the high-temperature gas flows, and prevents the flow path area of the high-temperature gas from decreasing and making it impossible to ensure the required flow rate even if a large number of brick fragments or the like fly in and are captured by the porous body 3, and has the advantage of extending the period until the flow rate of the high-temperature gas decreases.

Figure 3 is a schematic diagram showing yet another embodiment according to the present invention. This example is composed of two porous bodies 3, 3', each having a shape that is convex toward the downstream side of the flow path through which high-temperature gas flows, arranged at intervals along the axis L of the joint body 1 in a multi-stage arrangement. By arranging multiple porous bodies 3 at intervals in a multi-stage arrangement, even if flying brick fragments pass through the porous body 3 located upstream, the brick fragments can be captured by the porous body 3' located downstream.

When the porous bodies 3, 3' are arranged in multiple stages, the positions at which the porous bodies 3, 3' are supported may be the same as shown in the figure, but the distance h between the parts located within the internal path N should be sufficient to allow the porous body 3' located downstream to hold the brick pieces.

When the porous bodies 3, 3' are arranged in a multi-stage arrangement, the maximum passing size (maximum diameter of the opening) of the upstream porous body 3 is made larger than the maximum passing size of the downstream porous body 3', so that relatively large brick pieces can be collected by the upstream porous body 3, and bricks with sizes between the maximum passing size of the upstream porous body 3 and the downstream porous body 3' can be collected by the downstream porous body 3'.

It is also possible to install three or more porous bodies 3, 3'. In this case, if the maximum diameter of the opening of the most upstream porous body 3 is larger than the maximum diameter of any of the downstream porous bodies 3', the above function can be exerted, thereby suppressing the decrease in the flow area of each porous body 3, 3' and further extending the period until a decrease in the flow rate of the high-temperature gas occurs.

Figures 4, 5(a) and 5(b) are schematic diagrams showing another embodiment of an expansion joint according to the present invention. This expansion joint has a structure in which the tip portions 4c of the opposing support portions 4 extend beyond the refractory material 2a to the internal path N, and the edge portion 3a of the porous body 3 is supported on the support surface 4a of the support portion 4 via the anchor portion 4b.

In such a structure, for example, as shown in FIG. 5(a), two notches 3b slightly larger in size than the width dimension of the tip portion 4c of the support portion 4 are provided on the edge portion 3a of the porous body 3, and as shown in FIG. 6, the porous body 3 is moved from the downstream side to the upstream side of the expansion joint, that is, from the lower surface side to the upper surface side of the tip portion 4c of the support portion 4, while aligning the notches 3b of the porous body 3 with the tip portions 4c of each support portion 4. Next, when the porous body 3 passes through the tip portions 4c of the support portions 4, the porous body 3 is rotated in the circumferential direction as shown by the arrow in FIG. 5(a) to shift the position of the notches 3b from the tip portions 4c of the support portions 4, and the porous body 3 is supported by the support surface 4a of the support portions 4. To remove the porous body 3 supported by the support part 4, rotate the porous body 3 in the opposite direction to when it was attached, align the notch 3b of the opposing body 3 with the tip part 4c of the support part 4, and then move the porous body 3 from the upper surface side to the lower surface side of the support part 4.

Normally, in the piping system of a blast furnace, the lower bend 18 and spherical short pipe 17, which are relatively easy to remove, are located on the downstream side of the expansion joint, i.e., on the tuyere side, as shown in Figure 9, and the lower bend 18 and spherical short pipe 17 are removed when replacing the tuyere 9. However, when the expansion joint according to the present invention is used, the porous body 3 can be easily removed from the downstream side of the expansion joint when removing the lower bend 18 and spherical short pipe 17, so it is possible to remove the brick fragments captured in the porous body 3, and it is also possible to replace it with a new porous body 3.

The support part 4 may have a flat shape in side view (cross-sectional shape) as shown in FIG. 4, with the thickness being the same from the base end connected to the inner tube 1a to the tip part 4c. Alternatively, as shown in FIGS. 5(a) and (b), the shape in plan view (shown by virtual lines) and the shape in side view (cross-sectional shape) are preferably tapered, that is, the thickness becomes gradually or stepwise thinner from the base end connected to the inner tube 1a to the tip part 4c. This shape makes it easier for the support part 4 to be cooled from the outside of the inner tube 1a, improving the heat resistance of the support part 4.

Figure 7 is a schematic diagram showing another embodiment of an expansion joint according to the present invention. In Figure 7, reference numeral 5 denotes a through hole provided in the inner tube 1a constituting the peripheral wall of the joint body 1, 6 denotes a through hole provided in the refractory material 2a and connected to the through hole 5, 7 denotes a cylinder that passes through the outer tube 1c of the joint body 1 and is connected to the peripheral wall of the inner tube 1a and has a passage that connects to the through holes 5 and 6, and 8 denotes a lid that is detachably attached to the end of the cylinder 7.

The through holes 5, 6 and the passage of the cylinder 7 form a through opening for taking out the brick fragments captured in the porous body 3 to the outside. When the supply of hot air is stopped, such as when the blast furnace is stopped, the lid 8 is removed, the through opening is opened, and the brick fragments captured in the porous body 3 can be scraped out to the outside. In addition, in FIG. 7, a plate-shaped porous body 3 is used as an example to facilitate scraping out the brick fragments captured in the porous body 3, but if efficient scraping out of the brick fragments is possible, a porous body 3 as shown in FIG. 2 above may be used.

Cooling water can also be circulated through the gap M formed between the inner pipes 1a, 1b and the outer pipes 1c, 1d. By circulating cooling water, it is possible to protect the expansion joint from the heat of the high-temperature gas flowing through the internal path N, and also to effectively cool the support part 4 that supports the porous body 3.

By installing an expansion joint according to the present invention between the upper vent and lower vent that connect the annular pipe and the tuyere in the piping system for blowing hot air to the blast furnace, the tuyere of the blast furnace can be prevented from becoming clogged with brick fragments, enabling stable operation of the blast furnace, but the expansion joint according to the present invention can also be used in the piping systems of facilities other than blast furnaces.

The present invention provides an expansion joint that can prevent blockage of piping systems or clogging of blast furnace tuyere holes caused by foreign objects such as fallen bricks.

1 Joint body 1a, 1b Inner pipe 1c, 1d Outer pipe 2a, 2b Refractory material 3, 3' Porous body 3a Edge portion 3b Notch portion 4 Support portion 4a Support surface 4b Mooring portion 4c Tip portion 5 Through hole 6 Through hole 7 Cylinder 8 Lid 9 Tuyere 10 Hot blast furnace 11 Upper hot blast main pipe 12 Mixing and cooling pipe 13 Lower hot blast main pipe 14 Annular pipe 15 Upper bend 16 Expansion pipe 17 Spherical short pipe 18 Lower bend 19 Weir 20 Brick piece U1 Upstream pipe U2 Downstream pipe B1, B2 Bellows M Gap F1, F2 Flange N Internal path E Gap h Spacing

Claims (11)

An expansion joint that is installed in a pipe through which high-temperature gas flows from top to bottom and absorbs displacement accompanying expansion and contraction of the pipe due to thermal effects by its own expansion and contraction,
a joint body having an internal passage connected to a flow path of the piping and connectable between end faces of the piping, the internal passage of the joint body being provided with a porous body having a plurality of openings that allow the passage of high-temperature gas flowing through the flow path of the piping and the collection of flying objects ;
An expansion joint, characterized in that a thickness of the porous body in the flow direction of the high-temperature gas is smaller than a mesh size of the opening . The expansion joint described in claim 1, characterized in that the porous body has a shape that is convex toward the downstream side of the flow path. The expansion joint described in claim 1 or 2, characterized in that the porous bodies are arranged in multiple stages at intervals along the axis of the joint body. The expansion joint described in claim 3, characterized in that, among the porous bodies arranged in multiple stages, the porous body located at the most upstream side of the internal path has an opening size larger than the maximum size of the opening of any of the porous bodies located at the downstream side of the internal path. An expansion joint as described in any one of claims 1 to 4, characterized in that the joint body has support parts on its inner wall surface that support the porous body at at least two points. The expansion joint described in claim 5, characterized in that the porous body has a notch that allows the support part to pass through. The expansion joint according to claim 5 or 6, characterized in that at least one of the shapes of the support part in plan view and in side view is tapered. The expansion joint according to any one of claims 1 to 7, characterized in that the joint body has a through opening that is provided on the peripheral wall of the joint body via a lid that can be opened and closed, and that allows the matter captured in the porous body to be removed to the outside. the joint body includes an inner tube divided into at least two parts in a direction intersecting an axis of the joint body and connected to each other via a bellows, and an outer tube divided into at least two parts in a direction intersecting an axis of the joint body, connected to each other via a bellows, and surrounding the inner tube with a gap therebetween;
The expansion joint according to any one of claims 1 to 8, characterized in that the inner pipe has an internal passage through which the high-temperature gas passes, and the gap forms a circulation path for cooling water. The expansion joint according to claim 9, characterized in that the inner pipe has a refractory material on its inner wall surface. An expansion joint as described in any one of claims 1 to 10, characterized in that the piping through which the high-temperature gas flows is an upper bend and a lower bend that connect the tuyere of the blast furnace and the annular pipe.

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