Gas nozzle and combustion device

Abstract

The present application provides a kind of gas nozzle (31), which supplies fuel gas to combustor, and is shaped by the stamping processing of sheet material, with: the nozzle body (311) of cylindrical shape, with internal space (311a), fuel gas flows into the internal space;And end wall portion (312), it is located at the opposite side of the base end of nozzle body on the inflow side of fuel gas, nozzle hole (313) is formed in end wall portion, fuel gas that flows into the internal space of nozzle body is ejected from the nozzle hole, even if the drawing depth of nozzle body is shallow, it can make that combustion performance is stable and the generation of whistle sound is inhibited.The base of nozzle hole on the internal space (311a) side of nozzle body is provided with the expanding diameter portion that gradually expands in aperture diameter towards internal space.It is preferably that the distance (L) from the base end of nozzle body to end wall portion is set to the distance that can be deep-drawn formed by 1 time stamping processing, thereby it can reduce the stamping times and as far as possible reduce cost.

Description

Technical Field

[0001] The present invention relates to a gas nozzle for supplying fuel gas to a burner and a combustion device using the gas nozzle. Background Technology

[0002] Conventionally, gas nozzles of this type have been known to be formed by stamping sheet metal (see, for example, Patent Document 1). This gas nozzle comprises: a cylindrical nozzle body having an internal space into which fuel gas flows; and an end wall portion located opposite the base end of the nozzle body on the fuel gas inflow side. A nozzle orifice is formed in the end wall portion, through which the fuel gas flowing into the internal space is ejected.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-197971 Summary of the Invention

[0004] However, if the thickness of the sheet material used for the gas nozzle is reduced to lower costs, cracking is likely to occur when the nozzle body is drawn deeper through stamping. Therefore, when forming the gas nozzle using a thinner sheet material through stamping, it is necessary to reduce the drawing depth of the nozzle body.

[0005] However, in this situation, the airflow of combustion gases is not adequately rectified within the internal space of the nozzle body. As a result, the following undesirable phenomena are easily produced: combustion performance becomes unstable, producing a so-called whistling sound.

[0006] In view of the above problems, the object of the present invention is to provide a gas nozzle and a combustion device using the gas nozzle, which can stabilize combustion performance and suppress the generation of whistling sound even when the drawing depth of the nozzle body is reduced.

[0007] To address the aforementioned problems, the first invention of this application is a gas nozzle that supplies fuel gas to a burner and is formed by stamping a sheet metal. It comprises: a cylindrical nozzle body having an internal space into which fuel gas flows; and an end wall portion located opposite the base end of the nozzle body on the fuel gas inflow side, wherein a nozzle orifice is formed on the end wall portion, and the fuel gas flowing into the internal space is ejected from the nozzle orifice. The invention is characterized by an enlarged diameter portion, whose diameter gradually increases towards the internal space of the nozzle body, located at the base of the nozzle orifice on the internal space side of the nozzle body.

[0008] Furthermore, the second invention of this application is a combustion device comprising: a burner; and a heat exchanger heated by combustion gas from the burner, characterized in that the gas nozzle of the first invention described above is used as a gas nozzle for supplying fuel gas to the burner.

[0009] According to the present invention (first invention), the nozzle body has a shallow drawing depth, so even if the fuel gas flow is not fully rectified within the internal space of the nozzle body, the fuel gas flow is rectified by the expanded diameter portion at the base of the nozzle orifice. As a result, combustion performance is stabilized and the generation of whistling sounds is suppressed.

[0010] Furthermore, in this invention, the diameter expansion section is preferably formed such that the rate of increase in orifice diameter gradually increases towards the interior space of the nozzle body. Accordingly, compared to a structure in which the diameter expansion section is formed with a constant rate of increase in orifice diameter, the fuel gas ejected from the nozzle orifice maintains a faster velocity and travels a greater distance, while the amount of air flowing into the nozzle orifice from the outside is reduced.

[0011] Furthermore, in this invention, even if the drawing depth of the nozzle body is shallow, the performance will not deteriorate. Therefore, the drawing depth of the nozzle body, i.e., the distance from the base end of the nozzle body to the end wall, can be set to a distance that can be drawn into shape in a single stamping process. Accordingly, the number of stamping processes can be reduced, thereby minimizing costs. Attached Figure Description

[0012] Figure 1 This is a perspective view of a combustion device according to an embodiment of the present invention (the second invention).

[0013] Figure 2 Is Figure 1 A sectional side view cut at point II-II.

[0014] Figure 3 This is a perspective view taken from a slightly downward angle, showing the combustion device in the embodiment with the manifold separated.

[0015] Figure 4 This is a perspective view taken from the rear oblique position of a manifold with a gas nozzle according to an embodiment of the present invention (first invention).

[0016] Figure 5 yes Figure 4 A three-dimensional view of the manifold, showing the manifold body and cover separated, viewed from the oblique front.

[0017] Figure 6 Is Figure 4 An enlarged cross-sectional view of the gas nozzle of the first embodiment of the present invention, cut along line VI-VI.

[0018] Figure 7 This is the gas nozzle of the second embodiment of the present invention, and... Figure 6 The corresponding enlarged sectional view.

[0019] Figure 8 This is a line graph showing the velocity distribution of fuel gas ejected from the gas nozzle according to the first embodiment of the present invention.

[0020] Figure 9 This is a line graph showing the ejection velocity distribution of fuel gas from a gas nozzle according to the second embodiment of the present invention.

[0021] Figure 10 This is a line graph showing the velocity distribution of the fuel gas ejected from the gas nozzle of the comparative example.

[0022] Explanation of reference numerals in the attached figures

[0023] 2…burner, 31…gas nozzle, 311…nozzle body, 311a…internal space, 312…end wall, 313…nozzle orifice, 313a…expanded diameter section, L…distance from the base of the nozzle body to the end wall, 4…heat exchanger. Detailed Implementation

[0024] Reference Figure 1 , Figure 2 The combustion apparatus of an embodiment of the present invention (the second invention) includes: a combustion chamber 1; a plurality of burners 2 arranged side by side in the lower part of the combustion chamber 1; a manifold 3 that supplies fuel gas to the burners 2; and a heat exchanger 4 disposed in the upper part of the combustion chamber 1 and heated by the combustion gas from the burners 2.

[0025] The burners 2 are arranged side-by-side in a transverse direction. Each burner 2 is a flat burner with a flame opening that is elongated in the front-back direction in a horizontal direction orthogonal to the transverse direction at its upper end. A mixing tube section 21 is provided at the lower part of each burner 2. An inlet 22 that opens forward is provided at the front end of the mixing tube section 21. Furthermore, fuel gas ejected from each gas nozzle 31 of the manifold 3 (described later) flows into the inlet 22 of each burner 2, and primary air flows into the inlet 22, thereby generating a mixture of fuel gas and primary air in the mixing tube section 21. This mixture is then ejected from the flame opening of the burner 2 and combusted.

[0026] Also refer to Figure 3 A stepped portion 111 is formed at the front of the bottom plate 11 of the combustion chamber 1, rising upwards. An opening 112 is provided on this stepped portion 111, facing the inlet 22 of the mixing tube 21 of each burner 2. In this embodiment, six burners 2 are arranged side-by-side, thus six openings 112 are arranged side-by-side in the lateral direction. Furthermore, a plurality of upward-facing recesses 113 are formed on the bottom plate 11, spaced apart from the lower edges of each burner 2 on both lateral sides. Additionally, an electrode component 5 is mounted on the front plate 12 of the combustion chamber 1. This electrode component 5 includes: an ignition electrode 51 for igniting the burners 2; and a flame rod 52 for detecting the flame of the burners 2.

[0027] The heat exchanger 4 is a finned tube heat exchanger, comprising: multiple heat-absorbing fins 41 stacked laterally; and multiple heat-absorbing tubes 42 passing through the heat-absorbing fins 41. The heat-absorbing tubes 42 are connected in series by multiple U-shaped connecting pipes 43 on the upper outer surface of the combustion chamber 1. Furthermore, a water supply pipe 44 is connected to the upstream heat-absorbing tube 42, and a hot water outlet pipe 45 is connected to the downstream heat-absorbing tube 42.

[0028] A fan 7 is connected to the upper end of the combustion chamber 1 via an exhaust hood 6. A fan motor 71 is attached to the fan 7. Combustion gases passing through the heat exchanger 4 are drawn in by the fan 7. The combustion gases drawn in by the fan 7 are discharged to the outside via an exhaust pipe (not shown) connected to the outlet 72 of the fan 7. Additionally, as... Figure 3 As shown, a plurality of small holes 114 are formed in the bottom plate 11 of the combustion chamber 1. Furthermore, combustion air is supplied to each burner 2 by the suction force of the fan 7. That is, the air drawn from the inlet 22 through each opening 112 is supplied to each burner 2 as primary air for combustion, and the air drawn from the small holes 114 is supplied to each burner 2 as secondary air for combustion.

[0029] On the lower front end of the side plates 13 on both sides of the combustion chamber 1, there are tongue portions 131 that protrude forward more than the stepped portion 111 of the base plate 11. Furthermore, at the fixing portions 34 provided at the ends on both sides, the manifold 3 is fixed to the tongue portions 131 by screws 34a.

[0030] Reference Figure 4 to Figure 6 The manifold 3 is configured to include: a manifold body 3a; a plurality of gas nozzles 31, according to an embodiment of the present invention (first invention), which spray fuel gas toward the inlet 22 of the mixing tube section 21 of each burner 2 and are protruding from the manifold body 3a corresponding to the plurality of burners 2; and a cover 3b, which divides a fuel gas distribution chamber 32 between itself and the manifold body 3a. The cover 3b is welded to the manifold body 3a at its periphery. The manifold 3 also has an inlet 33. The aforementioned fixing part 34 and the inlet 33 are provided in the manifold body 3a. Fuel gas flows into the inlet 33 via a valve unit 8 connected to the inlet 33. Moreover, the fuel gas flowing in from the inlet 33 is distributed to each gas nozzle 31 via the distribution chamber 32 and sprayed from each gas nozzle 31 toward the inlet 22 of the mixing tube section 21 of each burner 2.

[0031] The manifold body 3a is formed by stamping a sheet metal such as a thin stainless steel plate. Similarly, the cover 3b is also formed by stamping a sheet metal thinner than that of the manifold body 3a. Naturally, the gas nozzles 31 protruding from the manifold body 3a are formed by stamping a sheet metal that is also the material of the manifold body 3a. Figure 6As shown, each gas nozzle 31 includes: a cylindrical nozzle body 311 having an internal space 311a into which fuel gas flows from the distribution chamber 32; and an end wall portion 312 located on the opposite side of the base end of the nozzle body 311 on the fuel gas inflow side. A nozzle orifice 313 is formed in the end wall portion 312, and the fuel gas flowing into the internal space 311a of the nozzle body 311 is ejected from the nozzle orifice 313.

[0032] Here, if the thickness of the sheet metal used as the material for the gas nozzle 31, i.e., the material for the manifold body 3a, is reduced to lower costs, cracking is likely to occur when the drawing depth of the nozzle body 311 is increased through stamping. Therefore, when forming the gas nozzle 31 by stamping a thinner sheet metal, it is necessary to reduce the drawing depth of the nozzle body 311. In particular, to minimize costs, it is desirable to set the drawing depth of the nozzle body 311, i.e., the distance L from the base end of the nozzle body 311 to the end wall 312, to a small distance that can be drawn in one stamping operation. For example, when the sheet metal used as the material for the manifold body 3a is a 1.2 mm thick stainless steel sheet (SUS304), the aforementioned distance L that can be drawn in one stamping operation is about 4 mm. However, in this case, the airflow of combustion gas is not sufficiently rectified in the internal space 311a of the nozzle body 311, which can easily lead to the following adverse conditions: unstable combustion performance or the generation of a so-called whistling sound.

[0033] Therefore, in this embodiment, an enlarged diameter portion 313a is provided at the base of the nozzle orifice 313 located on the side of the internal space 311a of the nozzle body 311, the orifice diameter of which gradually increases toward the internal space 311a of the nozzle body 311. Here, regarding Figure 6 The gas nozzle 31 of the first embodiment shown has an enlarged diameter portion 313a formed such that the orifice diameter expansion rate (the orifice diameter of the portion separated from the portion with orifice diameter R by a unit length of ΔD in the orifice axis direction is set as R+ΔR, and its value is represented by ΔR / ΔD) is constant, that is, the orifice diameter tends to expand linearly towards the internal space 311a of the nozzle body 311. On the other hand, regarding Figure 7 In the second embodiment of the gas nozzle 31 shown, the diameter expansion portion 313a is formed such that the rate of increase in orifice diameter tends to gradually increase towards the internal space 311a of the nozzle body 311, that is, the orifice diameter tends to expand in a curved shape towards the internal space 311a.

[0034] Regardless, as long as an expansion section 313a is provided at the base of the nozzle orifice 313, even if the fuel gas flow is not fully rectified in the internal space 311a of the nozzle body 311, the fuel gas flow will still be rectified by the expansion section 313a. As a result, combustion performance can be stabilized and the generation of whistling sounds can be suppressed.

[0035] To confirm the above effects, simulations were performed using fluid analysis software. The following conditions were set: the distance L from the base of the nozzle body 311 to the end wall 312 was 4 mm; the plate thickness of the end wall 312 was 0.8 mm; the diameter of the nozzle orifice 313 was 1.5 mm; and the gas supply pressure to the gas nozzle 31 was 1.0 kPa. Within a 0.2 mm range at the base of the nozzle orifice 313, regarding the gas nozzle 31 of the first embodiment, which is provided with an expansion portion 313a whose orifice diameter increases linearly at a 45° angle, the fuel gas ejection velocity distribution is as follows: Figure 8 As shown. Furthermore, within a 0.55mm range of the base of the nozzle orifice 313, for the gas nozzle 31 of the second embodiment, which has an enlarged diameter portion 313a that expands in a curved shape with a radius of curvature of 1.0mm, the fuel gas ejection velocity distribution is as follows: Figure 9 As shown. On the other hand, for the comparative example gas nozzle 31' which omits the enlarged diameter portion at the base of the nozzle orifice 313, the fuel gas ejection velocity distribution is as follows: Figure 10 As shown. Furthermore, in Figure 8 to Figure 10 In the diagram, the velocity of the outer portion of line a is 0–4.5 m / s; the velocity between line a and line b is 4.5–9.0 m / s; the velocity between line b and line c is 9.0–13.5 m / s; the velocity between line c and line d is 13.5–18.0 m / s; the velocity between line d and line e is 18.0–22.5 m / s; the velocity between line e and line f is 22.5–27.0 m / s; the velocity between line f and line g is 27.0–31.5 m / s; the velocity between line g and line h is 31.5–36.0 m / s; the velocity between line h and line i is 36.0–40.5 m / s; and the velocity of the inner portion of line i is 40.5–45.0 m / s.

[0036] For the gas nozzle 31 of the present invention (both the first and second embodiments), compared to the gas nozzle 31' of the comparative example, the fuel gas ejected from the nozzle orifice 313 maintains a faster velocity and reaches a greater distance. If the region with the faster ejected gas velocity reaches a greater distance in this way, the force required to supply primary air to the inlet 22 of the mixing tube 21 of the burner 2 increases, thereby stabilizing combustion performance. Furthermore, the portion between the orifice wall of the nozzle orifice 313 and line a is where air flows into the nozzle orifice 313 from the outside. Regarding the gas nozzle 31 of the present invention, compared to the gas nozzle 31' of the comparative example, the portion between the orifice wall of the nozzle orifice 313 and line a is narrower, thereby reducing the amount of air flowing into the nozzle orifice 313 from the outside. The inflow of air from the outside into the nozzle orifice 313 is a cause of whistling noise; therefore, the gas nozzle 31 of the present invention can suppress the generation of whistling noise.

[0037] Furthermore, regarding the distance traveled by the fuel gas ejected from the nozzle orifice 313 while maintaining a relatively high speed, the gas nozzle 31 of the second embodiment is longer than the gas nozzle 31 of the first embodiment. And, although Figure 9 The effect is not obvious, but the gas nozzle 31 of the second embodiment has less air flowing into the nozzle hole 313 from the outside compared with the gas nozzle 31 of the first embodiment.

[0038] The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited thereto. For example, the above embodiments apply the present invention to a plurality of gas nozzles 31 provided in a manifold 3, but the present invention can also be applied to a gas nozzle provided individually.

Claims

1. A gas nozzle for supplying fuel gas to a burner, formed by stamping a sheet metal, comprising: a cylindrical nozzle body having an internal space into which fuel gas flows; and an end wall portion located opposite the base end of the nozzle body on the fuel gas inflow side, wherein a nozzle orifice is formed in the end wall portion, through which the fuel gas flowing into the internal space is ejected. Its features are, An enlarged diameter section is provided at the base of the nozzle orifice located on the internal space side of the nozzle body, with the orifice diameter gradually increasing towards the internal space of the nozzle body. The enlarged diameter section is formed such that the aperture enlargement rate gradually increases towards the internal space of the nozzle body.

2. The gas nozzle according to claim 1, characterized in that, The distance from the base end of the nozzle body to the end wall is set to a distance that can be drawn into shape in one stamping process.

3. A combustion apparatus comprising: a burner; and a heat exchanger heated by combustion gases from the burner. Its features are, The gas nozzle as described in claim 1 or 2 is used as a gas nozzle for supplying fuel gas to the burner.

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