JP7744019B2 - chimney - Google Patents

Description

The present invention relates to a chimney equipped with a horizontal pipe that guides the exhaust flow emitted from an exhaust generation source into a flue formed by the internal space of the inner wall.

Large chimneys installed inside buildings, such as those constructed to guide and release exhaust flows from exhaust sources such as gas turbines and diesel engines that drive emergency generators, boilers, and industrial waste incinerators, are required to improve the exhaust efficiency of the exhaust flow rising up the flue. These types of chimneys are often cylindrical or rectangular, and generally have an insulating layer between an outer wall made of steel plate and an inner wall made of thin steel plate, as well as a horizontal pipe that guides the exhaust flow from the exhaust source into the flue.

As a measure to improve the exhaust efficiency of chimneys, a prior art example has been proposed for cylindrical chimneys, in which a deflector plate is placed at the outlet of a horizontal inlet pipe that introduces the exhaust flow sent from the exhaust source into the flue, and the action of this deflector plate causes the exhaust flow to swirl within the flue (see Patent Document 1). Another prior art example has been proposed, in which the exhaust flow is swirled by the action of spiral-shaped exhaust guide vanes placed within the flue of a cylindrical chimney (see Patent Document 2).

Japanese Utility Model Publication No. 63-44667 Publication No. 3226204

However, the prior art proposed in Patent Documents 1 and 2 is designed to swirl the exhaust flow along the inner surface of the flue of a cylindrical chimney, making it difficult to apply them directly to a rectangular chimney. Furthermore, Patent Document 1 requires an extra deflector plate, and Patent Document 2 requires extra exhaust guide vanes, resulting in problems such as increased costs and cumbersome construction.

The present invention was made in consideration of the above circumstances, and aims to provide a chimney that can be easily applied to chimneys of any shape, whether cylindrical, rectangular, or even oval cross section, and that can increase the exhaust efficiency of the exhaust flow rising through the flue, without requiring any additional deflector plates or exhaust guide vanes.

The chimney of the present invention has an insulating layer interposed between an outer wall and an inner wall made of thin steel plate, and is equipped with a horizontal pipe that guides the exhaust flow sent out from the exhaust source into a flue formed by the internal space of the inner wall. Grooves extending in a direction intersecting the axial direction of the inner wall are provided on the inner surface of the inner wall in parallel to the axial direction at multiple locations.

Analysis based on the "Simulation for Verifying Pressure Distribution in the Chimney" described below predicts that a chimney constructed in this manner reduces pressure loss in the exhaust flow through the chimney, increasing exhaust velocity and improving exhaust efficiency. This, in turn, predicts that a thinner chimney can be used to reduce installation space, thereby enabling the expansion of building floor space. Furthermore, the chimney of this invention utilizes thin steel plates for its inner wall, and utilizes this to form unidirectional grooves on the inner wall. This not only offers the advantage of easily forming the grooves through sheet metal processing such as bending, but also offers cost and construction advantages by eliminating the need for the deflector plates described in Patent Document 1 and the exhaust guide vanes described in Patent Document 2, as discussed above. Furthermore, the grooves intersecting the axial direction of the inner wall may be inclined, with the inclination angle of the grooves being approximately perpendicular to an imaginary plane perpendicular to the axial direction of the cylindrical inner wall, specifically within a range of 0 to 20 degrees. The meaning of "groove inclination angle" will be defined later in the description of the embodiments.

The present invention can be easily applied to cylindrical chimneys, rectangular chimneys, and even chimneys with an oval cross section. For cylindrical chimneys, a configuration can be adopted in which the thin steel plate forming the inner wall is cylindrical and the grooves extend in a spiral direction. This configuration makes it easy to uniformly arrange the spiral grooves around the entire circumference of the inner wall, which helps to uniformly distribute the pressure of the exhaust flow through the flue and improve exhaust efficiency. The spiral grooves may be inclined at a substantially right angle, specifically within a range of 0 to 20 degrees, to an imaginary plane perpendicular to the axial direction of the cylindrical inner wall.

Similarly, for a cylindrical chimney, the inner wall can be formed from the above-mentioned spirally wound thin steel plate, with the thin steel plates aligned axially on the inner wall at the downstream and upstream sides in the exhaust gas flow direction connected via a helically extending seam joint, and the above-mentioned grooves provided at multiple locations between two adjacent axial joints. With this configuration, the spirally wound thin steel plate, the spiral grooves formed in the thin steel plate, and the seam joints make it easy to absorb the effects of the exhaust flow temperature through the axial expansion and contraction of the inner wall, and also to suppress bending deformation of the inner wall. This makes it possible to easily use lightweight, inexpensive rock wool as an insulating layer between the outer and inner walls.

Next, for rectangular chimneys, it is preferable to adopt a configuration in which the thin steel plate constituting the inner wall is rectangular and the grooves extend perpendicular to the axis of the inner wall. With this configuration, the grooves extending perpendicular to the axis of the inner wall act as reinforcing ribs that reinforce the inner wall and help to increase the resistance to flexural deformation of the thin steel plate inner wall, making it easier to use lightweight, inexpensive rock wool as an insulating layer interposed between the outer and inner walls.

Furthermore, for chimneys with an oval cross section, it is preferable to adopt a configuration in which the thin steel plate constituting the inner wall has an oval cross section and the grooves extend in a direction perpendicular to the axis of the inner wall. With this configuration, the grooves extending in a direction perpendicular to the axis of the inner wall act as reinforcing ribs that reinforce the inner wall and help to increase the resistance to flexural deformation of the thin steel plate inner wall, which makes it easier to use lightweight, inexpensive rock wool as an insulating layer interposed between the outer and inner walls.

In the present invention, it is preferable that the groove depth of the above-mentioned grooves be 3 to 5 mm. If the groove depth of the grooves provided on the inner surface of the inner wall made of thin steel plate is too deep, it is predicted that this will increase the pressure loss of the exhaust flow, and conversely, if the groove depth is too shallow, it is thought that the significance of providing the grooves will be diluted. Analysis results based on the "Simulation to verify pressure distribution inside the flue" described below have predicted that pressure loss will be reduced if the groove depth is 3 to 5 mm.

In the present invention, it is desirable that the groove width of the grooves be 16 to 18 mm, and that the pitch between adjacent grooves in the axial direction be 30 to 40 mm. The groove width and the pitch between adjacent grooves should be determined taking into account the diameter of the inner wall, etc. For chimneys with an inner wall diameter of approximately 500 to 1500 mm, it is beneficial to set the groove width to 16 to 18 mm and the pitch between adjacent grooves to 30 to 40 mm.

As described above, the chimney of the present invention is likely to achieve the effect of reducing pressure loss of the exhaust flowing through the flue, increasing the exhaust speed, and improving exhaust efficiency. This also makes it possible to use a thin chimney, thereby reducing the installation space required, and expanding the building's floor area. Furthermore, the chimney of the present invention takes advantage of the use of thin steel plates for the inner wall, and utilizes this to form grooves extending in a certain direction on the inner wall. This not only has the advantage of making it easy to form the grooves by performing certain sheet metal processing such as bending on the inner wall, but also has the advantage in terms of cost and ease of construction, as it eliminates the need to provide additional deflection plates as described in Patent Document 1 or exhaust guide vanes as described in Patent Document 2, as explained at the beginning.

1 is a schematic cross-sectional plan view illustrating the basic configuration of a cylindrical chimney according to an embodiment of the present invention. FIG. FIG. 2 is a partial side view showing the inner wall of the cylindrical chimney of FIG. 1. FIG. 3 is a partially cutaway enlarged view showing part III in FIG. 2 . FIG. 4 is an end view taken along line IV-IV in FIG. 3. 10A, 10B, and 10C are cross-sectional views showing various shapes of grooves provided on the inner wall. FIG. 10 is an explanatory diagram showing comparative images of the analysis results based on the "simulation to verify pressure distribution inside the flue." FIG. 10 is a schematic cross-sectional plan view illustrating the basic configuration of a rectangular cylindrical chimney according to another embodiment of the present invention. FIG. 2 is a front view showing the inner surface of a panel-shaped thin steel plate. FIG. 9 is an end view taken along line IX-IX of FIG. 8. FIG. 10 is a schematic cross-sectional plan view illustrating the basic configuration of a chimney having an oval cross section according to yet another embodiment of the present invention. FIG. 2 is a partially cutaway side view showing a portion of an inner wall having an oval cross section.

Figure 1 is a schematic cross-sectional plan view illustrating the basic configuration of a cylindrical chimney according to an embodiment of the present invention. This chimney 100 is installed vertically, for example, in a void in a building's framework that serves as a space for constructing a chimney. In this type of chimney 100, the lower end is connected to the outlet of a horizontal inlet pipe (hereinafter referred to as a "horizontal pipe"; not shown in Figure 1) extending from an exhaust source such as a gas turbine, diesel engine, boiler, or waste incinerator installed in the building, while the upper end protrudes onto the roof of the building, for example.

The chimney 100 in Figure 1 has an insulating layer 30 approximately 50 to 100 mm thick interposed between an outer wall 10 made of a shape-retaining steel plate approximately 4 to 9 mm thick and an inner wall 20 made of a thin steel plate such as a thin stainless steel plate. Rock wool is used for the insulating layer 30. Zonolite-based calcium silicate board, which has low thermal shrinkage and excellent insulation, heat resistance, acid resistance, and abrasion resistance, could also be used for the insulating layer 30. However, in the case of a cylindrical chimney 100, taking into account the excellent resistance to flexural deformation achieved by the geometric characteristics of the cylindrical inner wall 20, it is advantageous to use rock wool alone or in combination with a composite of rock wool and ceramic fiber from the standpoints of cost, construction, and weight reduction.

Figure 2 is a partial side view showing the inner wall 20 of the cylindrical chimney, Figure 3 is a partially cutaway enlarged view showing part III in Figure 2, and Figure 4 is an end view taken along line IV-IV in Figure 3.

The cylindrical inner wall 20 shown in Figures 2 and 3 is made of thin steel plate. A thin stainless steel plate with a thickness of approximately 0.6 to 2 mm can be used as this thin steel plate. The diameter of the inner wall 20 is set to approximately 500 to 1500 mm, and the internal space of this inner wall 20 forms the flue. The cylindrical inner wall 20 is formed from thin steel plate wound spirally to form a tube. As shown in Figure 2, the spirally wound thin steel plate is arranged axially, with the thin steel plate 21a on the downstream side of the exhaust gas flow direction (upper in the figure) and the thin steel plate 21b on the upstream side of the exhaust gas flow direction (lower in the figure) connected to each other via a joint 22 made of a spirally extending seam (the exhaust gas flow direction is indicated by arrow F in Figures 3 and 4). As shown in Figure 4, the joint 22, formed by a seam joint, has an outward folded piece 22a formed by folding back the end of the thin steel plate 21a downstream in the exhaust gas flow direction outward, and an outward folded piece 22b formed by folding back the end of the thin steel plate 21b upstream in the exhaust gas flow direction outward. This interlocking structure allows the joint 22 to absorb the expansion and contraction of the inner wall 20. Furthermore, in the illustrated joint 22, the inner surfaces of the thin steel plate 21a downstream in the exhaust gas flow direction and the thin steel plate 21b upstream in the exhaust gas flow direction are flush and continuous, allowing rainwater and condensation to drip off without stagnation. This prevents rainwater and condensation from penetrating the insulation layer 30 and reducing its insulation performance.

The inner wall 20 also has linear bulges 23 with a mountain-shaped cross section that extend spirally parallel to the joints 22 formed by the above-mentioned seam joints. In this embodiment, the inner wall 20 is made of a thin steel plate that is easily machined, such as sheet metal processing, making it easy to form the linear bulges 23. The groove-shaped inner surface of the linear bulge 23 is formed as the groove strips 24 shown in Figure 3. Therefore, in this inner wall 20, groove strips 24 extending in a direction intersecting the axial direction (which coincides with the exhaust gas flow direction F) are provided in parallel at multiple locations along the axial direction of the inner wall 20. In the example shown in Figure 3, groove strips 24 are provided at three locations between two adjacent joints 22, 22. However, groove strips 24 may be provided at two or one location between two adjacent joints 22, 22, or at more than three locations.

Figures 5(A), (B), and (C) show various shapes of grooves 24 provided in the inner wall 20. The groove 24 shown in Figure 5(A) has an arc-shaped cross section, the groove 24 shown in Figure 5(B) has an angular cross section, and the groove 24 shown in Figure 5(C) has a V-shaped cross section. The cross-sectional shape of the groove 24 may be a shape other than that shown, such as a semi-elliptical shape. In such grooves 24, it is desirable that the groove depth d is 3 to 5 mm, the groove width w is 16 to 18 mm, and the pitch p between adjacent grooves 24, 24 in the axial direction is 30 to 40 mm. The groove width w of the grooves 24 and the pitch p between adjacent grooves should be determined taking into account the inner wall diameter D (see Figure 2), and for chimneys with inner wall diameters of approximately 500 to 1500 mm, it is beneficial to set the groove width at 16 to 18 mm and the pitch between adjacent grooves at 30 to 40 mm.

In a cylindrical chimney 100, it is known that the smaller the pressure loss (negative pressure) in the exhaust flow introduced into the flue entrance, the faster the exhaust flow will be discharged through the flue, improving exhaust efficiency. Therefore, the inventors of the present application examined the pressure distribution in the exhaust flow introduced into the flue from the horizontal pipe for various chimney models. The results are shown in Figure 6.

Figure 6 is an explanatory diagram showing comparative images of the analysis results based on a "simulation to verify pressure distribution within the flue." Figures (A), (B), and (C) show the pressure distribution in the exhaust flow entering the flue at the connection between the horizontal pipe 200 and the chimney's inner wall 20. Figure (A) shows the case where the inner wall 20 does not have grooves; Figure (B) shows the case where two grooves 24 are provided between two adjacent joints 22; and Figure (C) shows the case where three grooves 24 are provided between two adjacent joints 22 (see Figure 3 for the joints 22 and grooves 24). The simulation was conducted under conditions of a wind speed of 35 m/sec, and negative pressure was indicated in the colored areas: blue area I, dark blue area B, green area G, yellow area Y, and orange area O. The degree of negative pressure decreases in the following order: indigo area I > dark blue area B > green area G > yellow area Y > orange area O.

In Figure 1A, the presence of a blue region I consisting of vortices within the dark blue region B was observed directly above the flue entrance. In Figure 1B, the presence of a dark blue region B consisting of small vortices within the green region G was observed. Furthermore, in Figure 1C, the presence of a dark blue region B with a blurred outline consisting of small vortices within the green region G was observed. These analysis results indicate that the pressure loss at the flue entrance decreases in the following order: when the inner wall 20 has no grooves (Figure 1A), when grooves 24 are provided at two locations between two adjacent joints 22, 22 (Figure 1B), and when grooves 24 are provided at three locations between two adjacent joints 22, 22 (Figure 1C). Therefore, the chimney 100 according to the embodiment exhibits a faster exhaust flow velocity in the flue and improved exhaust efficiency compared to an inner wall 20 without grooves 24. It can also be seen that the narrower the pitch p between adjacent grooves 24, 24, the faster the flow rate of the exhaust gas in the flue, improving exhaust efficiency.

The above describes a chimney 100 in which a spiral groove 24 is provided on the cylindrical inner wall 20. In the chimney 100, the groove 24 may be inclined at a substantially right angle, specifically within a range of 0 to 20 degrees, to an imaginary plane perpendicular to the axial direction of the cylindrical inner wall 20. An inclination angle closer to 0 degrees relative to the imaginary plane is particularly desirable. Here, the "inclination angle of the groove 24" is defined as the inclination angle of a linear groove, which can be recognized by regarding a short portion of the circumferential direction of the three-dimensional curved groove 24 as a linear groove approximating the three-dimensional curve, since the groove 24 represents a three-dimensional curve. As shown in Figure 2, the axis of the cylindrical inner wall 20 is designated by the symbol Y, the imaginary plane by the symbol P, and the regarded linear groove 24 (see Figure 3) by the symbol G. The inclination angle is then represented by the symbol θ.

In chimneys 100 that require a large-diameter cylindrical inner wall 20, such as large chimneys 100 installed inside buildings, the inner wall 20 can be formed by spirally winding thin steel plate as described above. Alternatively, the inner wall 20 can be formed by rolling thin steel plate into a cylindrical shape and welding the butt joints of the circumferential ends together. For inner walls 20 made in this way, it is desirable to provide endless annular grooves perpendicular to the axial direction in multiple parallel positions along the axial direction. Adopting this configuration simplifies manufacturing.

Figure 7 is a schematic cross-sectional plan view illustrating the basic configuration of a rectangular cylindrical chimney 100 according to another embodiment of the present invention. This chimney 100 has an outer wall 10 made of shape-retaining steel plates approximately 4 to 9 mm thick assembled into a rectangular cylindrical shape, and an inner wall 20 made of thin steel panels, such as thin stainless steel plates approximately 0.6 to 2 mm thick assembled into a rectangular cylindrical shape. An insulating layer 30 approximately 50 to 100 mm thick is interposed between the outer wall 10. Zonolite calcium silicate boards are typically used for the insulating layer 30.

Figure 8 is a front view showing the inner surface of the panel-shaped thin steel plate 25 used in the rectangular cylindrical inner wall 20, and Figure 9 is an end view of the portion along line IX-IX in Figure 8.

As shown in Figures 8 and 9, numerous horizontally extending grooves 26 are formed at intervals in the vertical direction on the inner surface of the panel-shaped thin steel plates 25 that make up the inner wall 20. Therefore, on the inner surface of the rectangular cylindrical inner wall 20, which is formed by combining panel-shaped thin steel plates 25 into a rectangular cylindrical shape, grooves 26 extending in a direction perpendicular to the axial direction of the inner wall 20 are formed in multiple locations in the axial direction. In this embodiment, the inner wall 20 is made of thin steel plates that are easy to machine, such as sheet metal processing, so the above-mentioned grooves 26 can be easily formed.

As such, even in a rectangular chimney 100 employing an inner wall 20 with multiple parallel grooves 26 extending perpendicular to the axial direction, it is known that the lower the pressure loss in the exhaust flow entering the flue entrance, the faster the exhaust flow exits the flue, improving exhaust efficiency. Furthermore, the analysis results based on the "simulation to verify pressure distribution within the flue" described with reference to Figure 6 are believed to be similarly applicable to the rectangular chimney 100. Therefore, the rectangular chimney 100 according to this embodiment also achieves a faster exhaust flow velocity in the flue, improving exhaust efficiency, compared to a rectangular chimney whose inner wall 20 does not have grooves 26. Furthermore, the narrower the pitch between adjacent grooves 26, 26, the faster the exhaust flow velocity in the flue, improving exhaust efficiency.

In addition, in the rectangular chimney 100 according to the embodiment, the grooves 26 on the inner wall 20 also function as reinforcing ribs that reinforce the thin steel panel. This allows the inner wall 20 to exhibit excellent resistance to flexural deformation. Typically, a zonolite-based calcium silicate board, which is a molded body, is used as the insulating layer to prevent the inner wall from flexing, and the inner wall is placed on top of this molded body to prevent flexural deformation. However, as described above, the grooves 26 on the inner wall 20 also function as reinforcing ribs that reinforce the thin steel panel, allowing the inner wall 20 to exhibit excellent resistance to flexural deformation. Therefore, instead of the zonolite-based calcium silicate board, rock wool, which is advantageous in terms of cost, ease of installation, and weight reduction, can be used alone or in combination with a composite of rock wool and ceramic fiber for the insulating layer 30.

In this embodiment, the grooves 26 are shown to have an arc-shaped cross section in the inner wall 20, but the grooves 26 may also have an angular or V-shaped cross section. Furthermore, it is desirable that the groove depth be 3 to 5 mm, the groove width be 16 to 18 mm, and the pitch between adjacent grooves 26, 26 in the axial direction be 30 to 40 mm. The groove width of the grooves 26 and the pitch between adjacent grooves should be determined taking into account the diameter of the inner wall, etc.

Figure 10 is a schematic cross-sectional plan view illustrating the basic configuration of a chimney 100 with an oval cross section according to yet another embodiment of the present invention. The chimney 100 with an oval cross section in the illustration has two flat wall sections 101, 101 of equal width and two semicircular arc wall sections 102, 102 on either side of these flat wall sections 101. This chimney 100 also has an oval outer wall 10 made of a shape-retaining flat steel plate approximately 4 to 9 mm thick, and an oval inner wall 20 made of a thin steel plate such as a thin stainless steel plate approximately 0.6 to 2 mm thick. An insulating layer 30 approximately 50 to 100 mm thick is interposed between the outer wall 10 and the oval inner wall 20. A zonolite-based calcium silicate board is typically used for the insulating layer 30.

Figure 11 is a partially cutaway side view showing a portion of the inner wall 20, which has an oval cross section. In this embodiment, the inner wall 20, which has an oval cross section, has a large number of endless oval grooves 27 formed at intervals in the vertical direction. Therefore, the inner surface of the inner wall 20, which has an oval cross section, has grooves 27 extending in a direction perpendicular to the axial direction of the inner wall 20, and these grooves 27 are formed in multiple locations in the axial direction. In this embodiment, the inner wall 20 is made of a thin steel plate, which is easily amenable to machining such as sheet metal processing, so the above-mentioned grooves 27 can be easily formed.

As described above, even in a chimney 100 with an oval cross section and an inner wall 20 having multiple parallel grooves 27 extending perpendicular to the axial direction, it is known that the smaller the pressure loss in the exhaust flow introduced into the flue entrance, the faster the exhaust flow exits the flue, improving exhaust efficiency. Furthermore, the analysis results based on the "simulation to verify pressure distribution within the flue" described with reference to Figure 6 are believed to be similarly applicable to the chimney 100 with an oval cross section. Therefore, the chimney 100 with an oval cross section according to this embodiment also has a faster exhaust flow velocity in the flue, improving exhaust efficiency, compared to a chimney with an oval cross section whose inner wall 20 does not have grooves 27. Furthermore, the narrower the pitch between adjacent grooves 27, 27, the faster the exhaust flow velocity in the flue, improving exhaust efficiency.

In addition, in the chimney 100 having an oval cross section according to the embodiment, the grooves 27 on the inner wall 20 also function as reinforcing ribs that reinforce the thin steel plate that forms the inner wall 20. This allows the inner wall 20 to exhibit excellent resistance to flexural deformation. Typically, a zonolite-based calcium silicate board, which is a molded body, is used as the insulating layer to prevent the inner wall from flexing, and the inner wall is placed on top of this molded body to prevent flexural deformation. However, as described above, the grooves 26 on the inner wall 20 also function as reinforcing ribs that reinforce the panel-shaped thin steel plate, allowing the inner wall 20 to exhibit excellent resistance to flexural deformation. Therefore, instead of the zonolite-based calcium silicate board, rock wool, which is advantageous in terms of cost, ease of installation, and weight reduction, can be used alone or in combination with a composite of rock wool and ceramic fiber for the insulating layer 30.

In this embodiment, the grooves 27 are shown to have an arc-shaped cross section in the inner wall 20, but the grooves 27 may have an angular or V-shaped cross section. Furthermore, it is desirable that the groove depth is 3 to 5 mm, the groove width is 16 to 18 mm, and the pitch between adjacent grooves 27, 27 in the axial direction is 30 to 40 mm. The groove width of the grooves 27 and the pitch between adjacent grooves should be determined taking into consideration the diameter of the inner wall, etc.

10 Outer wall 20 Inner wall 22 Joint 24, 26, 27 Groove 30 Heat insulating layer 100 Chimney 200 Horizontal pipe F Flow direction of exhaust air (axial direction)
d: Groove depth w: Groove width p: Inter-groove pitch

Claims (2)

A chimney having an insulating layer interposed between an outer wall and an inner wall made of a thin steel plate, and having a horizontal pipe that guides an exhaust flow sent out from an exhaust generation source to a flue formed by an internal space of the inner wall,
On the inner surface of the inner wall, grooves extending in a direction intersecting the axial direction of the inner wall are provided in parallel at multiple locations in the axial direction,
A chimney characterized in that the thin steel plate constituting the inner wall is rectangular cylindrical, and the grooves extend in a direction perpendicular to the axis of the inner wall . A chimney having an insulating layer interposed between an outer wall and an inner wall made of a thin steel plate, and having a horizontal pipe that guides an exhaust flow sent out from an exhaust generation source to a flue formed by an internal space of the inner wall,
On the inner surface of the inner wall, grooves extending in a direction intersecting the axial direction of the inner wall are provided in parallel at multiple locations in the axial direction,
A chimney characterized in that the thin steel plate constituting the inner wall has an oval cross section, and the grooves extend in a direction perpendicular to the axis of the inner wall .