Expansion joints

Abstract

To provide an expansion joint capable of avoiding piping system obstruction or clogging of a tuyere of a blast furnace, which are caused by foreign matter such as a fallen brick.SOLUTION: An expansion joint, which is provided in piping for circulating high-temperature gas, absorbs displacement, which is associated with expansion and contraction caused by the thermal effect of the piping, by its own expansion and contraction. The expansion joint comprises a joint body which has an internal path connected to a channel of the piping and which can be connected between mutual end surfaces of the piping. A porous body, in which a plurality of openings enabling the passage of the high-temperature gas circulated through the channel of the piping is formed, is provided in the internal path of the joint body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an expansion joint that is installed in a part of a piping system through which high-temperature gas flows. [Background technology]

[0002] The overall configuration of a typical blast furnace is shown diagrammatically in FIG. 8, and a main part of FIG. 8 is shown enlarged in FIG. 9.

[0003] 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 1,200°C generated in a hot blast stove 10 passes from the tuyere 9 through a flow path including an upper hot blast main pipe 11, a mixing and cooling pipe 12, a lower hot blast main pipe 13, and an annular pipe 14, which are lined with refractory material, and further through an upper bend 15, an expansion pipe 16, a spherical short pipe 17, and a lower bend 18, before being blown into the blast furnace from each tuyere 9.

[0004] Meanwhile, iron ore, coke and auxiliary materials are charged from the top of the blast furnace, and when they come into contact with hot air (high-temperature reducing gas) blown in from the tuyere 9, they are melted to produce pig iron, promoting the reduction of the iron ore and other materials inside the blast furnace.

[0005] Stable operation is one of the most important issues in blast furnace operation. If the blast furnace cannot operate stably, it may be necessary to temporarily stop blowing hot air. One of the causes of such temporary shutdowns is clogging of the tuyere with bricks or other objects.

[0006] 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 fallen bricks or their fragments are carried downstream along with the hot air, causing blockage at the tip of the tuyere, which is the narrowest point in the flow path.

[0007] To prevent such trouble, it is important to prevent bricks from falling off. Although sufficient measures have been taken to prevent bricks from falling off during the design and construction stages of blast furnaces and their auxiliary equipment, in reality, it has not been possible to completely prevent bricks from falling off.

[0008] 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 fallen brick pieces 20 from entering by this weir 19.

[0009] In the conventional method described above, it was possible to reduce the probability of fallen bricks entering the building to a certain extent. However, 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.

[0010] As prior art related to expansion joints, for example, the technology disclosed in Patent Document 1 can be referred to; however, there is no mention of preventing clogging of tuyere or blockage of piping system caused by fallen bricks. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 4-228509 Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide an expansion joint that can prevent blockage of a piping system or clogging of a blast furnace tuyere due to foreign objects such as fallen bricks. [Means for solving the problem]

[0013] As a result of extensive research into preventing blockage of the piping system and clogging of the tuyere of a blast furnace caused by foreign objects such as fallen bricks, the inventors have come to solve the problem by focusing on an expansion pipe installed in the piping. An expansion pipe, also called an expansion joint, is installed in a part of the piping system upstream of the tuyere of a blast furnace as exemplified in the above Patent Document 1, and has the function of absorbing displacement caused by thermal expansion and contraction of the piping.

[0014] 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 the internal passage of the joint body is provided with a 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.

[0015] 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 support parts on its inner wall surface that support the porous body at at least two points, the porous body has a notch part that allows the support part to pass through, at least one of the shapes of the support part in a plan view and a shape in a side view has a tapered shape, and the joint body has a cover attached to a peripheral wall of the joint body. the joint body having an inner pipe divided into at least two in a direction intersecting the axis of the joint body and connected to each other via a bellows, and an outer pipe divided into at least two in a direction intersecting the axis of the joint body and connected to each other via a bellows, surrounding the inner pipe across a gap, the inner pipe having an internal path through which the high-temperature gas passes, the gap forming a circulation path for cooling water; the inner pipe having a refractory material on its inner wall surface; and further, the piping through which the high-temperature gas passes is an upper bend and a lower bend connecting a tuyere and an annular pipe of a blast furnace. Effect of the Invention

[0016] According to the present invention, bricks flying through the piping can be collected by the porous body installed inside the contraction joint, so that blockage of the piping system or clogging of the tuyere of the blast furnace does not occur.

[0017] In particular, by disposing the expansion joint of the present invention between an upstream piping connected to the annular pipe of a blast furnace and a 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. Also, since the tuyere is often replaced in a blast furnace, brick fragments collected at the expansion joint during this replacement can be easily recovered. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of an 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 AA of (a). [Diagram 2] FIG. 10 is a schematic diagram showing another embodiment of an expansion joint according to the present invention. [Diagram 3] FIG. 13 is a schematic diagram showing yet another embodiment of the expansion joint according to the present invention. [Figure 4] FIG. 10 is a schematic diagram showing another embodiment of an expansion joint according to the present invention. [Diagram 5] 5A and 5B are diagrams showing a schematic view of still another embodiment of the expansion joint according to the present invention, in which (a) is a plan view thereof, and (b) is a BB cross-sectional view of (a). [Figure 6] FIG. 6 is an explanatory diagram of a method for attaching a porous body to the expansion joint shown in FIG. 5. [Figure 7] FIG. 2 is a diagram showing a schematic diagram of another embodiment of an expansion joint according to the present invention, where (a) is a plan view, and (b) is a CC sectional view of (a). [Figure 8] FIG. 1 is a diagram showing a schematic diagram of the overall configuration of a blast furnace. [Figure 9] FIG. 9 is an enlarged view (partially in cross section) of a main portion of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 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 line AA of (a).

[0020] Reference numeral 1 in Figures 1(a) and 1(b) denotes a joint body that can be connected to the end faces of the upstream pipe U1 and the downstream pipe U2, respectively. In Figures 1(a) and 1(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.

[0021] The joint body 1 is composed of inner pipes 1a, 1b which are divided into two in a direction 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 in a direction 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, and the bellows B1, B2 expand and contract appropriately to absorb displacement accompanying expansion and contraction of the pipes U1, U2 due to thermal effects.

[0022] The inner pipe 1a and the outer pipe 1c, and the inner pipe 1b and the outer pipe 1d are integrally connected at the flanges F1 and F2 provided at their ends (upper end and lower end), and the pipe U1 located on the upstream side and the pipe U2 located on the downstream side 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.

[0023] 1(a) and 1(b), reference numerals 2a and 2b denote cylindrical refractories provided on the inner wall surfaces of the inner pipes 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 an end face 2a1 of the refractory 2a of the inner pipe 1a and an end face 2b1 of the refractory 2b of the inner pipe 1b, and the expansion joint expands and contracts within the range of this gap E.

[0024] 1(a) and 1(b) denotes a plate-like porous body that is disposed in the internal path N and has a plurality of openings 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 net, such as a punched metal, a wire net, or an expanded metal.

[0025] 1(a) and 1(b) denotes a support part integrally provided on the inner wall surface of the inner pipe 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 hooking it onto 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 pipe 1a, or at three or more equally spaced positions around the inner wall surface.

[0026] 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, U2 can be captured by the porous body 3, thereby preventing clogging in the piping system and at the tuyere.

[0027] It is preferable to use a heat-resistant metal for the porous body 3, and the type of metal and structure (the size of the openings, the spacing between openings, and if a wire mesh is used, the size of the openings and wire diameter, etc.) are determined so as to ensure the strength necessary to withstand the temperature range of high-temperature gas such as hot air and against which brick fragments fly.

[0028] The size of the opening of the porous body 3 also affects the airflow resistance, so the structure of the porous body 3 is selected taking the airflow resistance into consideration. As a specific example of the porous body 3 that can be used under normal blast furnace operating conditions, it is preferable to use a wire mesh manufactured using heat-resistant stainless steel (SUS310S), SUH steel, or a heat-resistant alloy, with a wire diameter of about 3 to 20 mm and a mesh size of about 5 to 50 mm. The mesh size of the wire mesh is preferably set so that foreign objects such as fallen bricks do not pass through the wire mesh and clog the inside of the pipe from the expansion joint to the tip of the tuyere. In addition, in order to ensure the strength of the porous body 3, the meshes can be layered to form a double structure.

[0029] 2 is a schematic diagram showing another embodiment of an expansion joint according to the present invention, in which the porous body 3 is recessed in the direction of the high-temperature gas flow, that is, has a convex shape toward the downstream side of the flow path through which the high-temperature gas flows.

[0030] The shape of the porous body 3 is preferably such that the central portion of the porous body 3 protrudes toward the downstream side of the flow path through which the high-temperature gas flows, further than the edge portion 3a of the porous body 3 supported by the support portion 4. This has the advantage that the total area of ​​the portion through which the high-temperature gas flows can be increased, and it is possible to prevent a situation in which the flow path area of ​​the high-temperature gas decreases and the necessary flow rate cannot be secured even if a large number of brick fragments or the like fly in and are captured by the porous body 3, and the period until the flow rate of the high-temperature gas decreases can be extended.

[0031] Fig. 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. By arranging a plurality of porous bodies 3 at intervals in a multi-stage arrangement, even if flying brick fragments pass through the porous body 3 located on the upstream side, the brick fragments can be captured by the porous body 3' located on the downstream side.

[0032] 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 spacing h between the parts located within the internal path N need only be sufficient to enable the porous body 3' located downstream to hold the brick pieces.

[0033] 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 sized brick pieces can be collected by the upstream porous body 3, and bricks whose sizes are between the maximum passing size of the upstream porous body 3 and the maximum passing size of the downstream porous body 3' can be collected by the downstream porous body 3'.

[0034] 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-mentioned function can be exerted, thereby suppressing the reduction in the flow area of ​​each porous body 3, 3' and further extending the period until a reduction in the flow rate of the high-temperature gas occurs.

[0035] 4, 5(a) and 5(b) are schematic diagrams showing another embodiment of the expansion joint according to the present invention. This expansion joint has a structure in which the tip portions 4c of the opposing support parts 4 are extended beyond the refractory material 2a to the internal passage N, and the edge portion 3a of the porous body 3 is supported on the support surface 4a of the support part 4 via the anchoring portion 4b.

[0036] In such a structure, for example, as shown in FIG. 5(a), two cutout portions 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 cutout portions 3b of the porous body 3 are aligned with the tip portions 4c of each support portion 4 while the porous body 3 is moved from the downstream side to the upstream side of the expansion joint, i.e., from the lower surface side to the upper surface side of the tip portion 4c of the support portion 4. Next, once the porous body 3 has passed through the tip portions 4c of the support portions 4, the porous body 3 is rotated circumferentially as shown by the arrow in FIG. 5(a) to shift the position of the cutout portions 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, the porous body 3 is rotated in the opposite direction to that at the time of attachment so that the cutout portion 3b of the opposing body 3 is aligned with the tip portion 4c of the support part 4, and then the porous body 3 is moved from the upper side to the lower side of the support part 4.

[0037] Usually, in the piping system of a blast furnace, a lower bend 18 and a 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 FIG. 9, and when replacing the tuyere 9, the lower bend 18 and the spherical short pipe 17 are removed. However, when the expansion joint according to the present invention is used, when removing the lower bend 18 and the spherical short pipe 17, the porous body 3 can be easily removed from the downstream side of the expansion joint, so that 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.

[0038] The support part 4 can have a flat shape in side view (cross-sectional shape) as shown in Figure 4, in which the thickness is the same from the base end connected to the inner tube 1a to the tip portion 4c. Alternatively, it is preferable to use a shape in plan view (shown by virtual lines) and a shape in side view (cross-sectional shape) as shown in Figures 5(a) and (b), in which the thickness becomes gradually or stepwise thinner from the base end connected to the inner tube 1a to the tip portion 4c. By using such a shape, the support part 4 can be easily cooled from the outside of the inner tube 1a, improving the heat resistance of the support part 4.

[0039] 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 inner pipe 1a constituting the peripheral wall of joint body 1, 6 denotes a through hole provided in refractory material 2a and connected to through hole 5, 7 denotes a cylinder that penetrates outer pipe 1c of joint body 1 and is connected to the peripheral wall of inner pipe 1a and has a passage that connects to through holes 5 and 6, and 8 denotes a lid that is detachably provided on the end of cylinder 7.

[0040] 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, and when the supply of hot air is stopped, such as when the blowing of air into the blast furnace is stopped, the lid 8 is removed to open the through opening, and the brick fragments captured in the porous body 3 can be scraped out to the outside. Note that, 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 a porous body 3 as shown in Fig. 2 above may be used as long as the brick fragments can be scraped out efficiently.

[0041] Cooling water can 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.

[0042] By providing an expansion joint according to the present invention between an upper vent and a lower vent connecting an annular pipe and a tuyere in a piping system for blowing hot air to a 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. [Industrial Applicability]

[0043] According to the present invention, it is possible to provide an expansion joint that can prevent blockage of a piping system or clogging of a blast furnace tuyere due to foreign objects such as fallen bricks. [Explanation of symbols]

[0044] 1 Fitting body 1a, 1b inner tube 1c, 1d outer tube 2a, 2b Refractories 3, 3′ Porous body 3a Edge 3b Cutout 4 Support part 4a Support surface 4b Mooring section 4c Tip part 5 Through hole 6 Through holes 7 Cylinder 8 Lid 9 Tuyere 10 hot stove 11 Upper hot air main 12 Mixed cooling pipe 13 Lower hot air main 14 Circular pipe 15 Upper Bend 16 Telescopic tube 17 Spherical short tube 18 Lower Bend 19 Weir 20 Brick Pieces U1 Upstream piping U2 Downstream piping B1, B2 Bellows M Gap F1, F2 flanges N Internal Route E Gap h interval

Claims

1. 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.

2. 2. The expansion joint according to claim 1, wherein the porous body has a shape that is convex toward the downstream side of the flow path.

3. 3. The expansion joint according to claim 1, wherein the porous bodies are arranged in multiple stages at intervals along the axis of the joint body.

4. The expansion joint according to 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 passage has an opening size larger than the maximum size of the openings of any of the porous bodies located at the downstream side of the internal passage.

5. The expansion joint according to any one of claims 1 to 4, characterized in that the joint body has support portions on its inner wall surface that support the porous body at at least two locations.

6. 6. The expansion joint according to claim 5, wherein the porous body has a notch that allows the support portion to pass through.

7. 7. The expansion joint according to claim 5, wherein at least one of the shapes of the support portion in a plan view and a side view is tapered.

8. The expansion joint according to any one of claims 1 to 7, characterized in that the joint body has a through opening provided on a peripheral wall of the joint body via a lid body that can be opened and closed, and that allows the matter collected in the porous body to be removed to the outside.

9. 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.

10. 10. The expansion joint according to claim 9, wherein the inner pipe has a refractory material on its inner wall surface.

11. The expansion joint according to 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 connecting a tuyere and an annular pipe of a blast furnace.

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