Patent Application
20200263871
The present invention relates to a burner device for mixing and burning, for example, a fuel gas such as hydrogen gas and another kind of gas.
In recent years, a burner device that utilizes hydrogen as fuel has been suggested for realizing a so-called low-carbon society in order to reduce emissions of carbon dioxide that causes environmental issues such as global warming (for example, see Patent Document 1).
[Patent Document 1] U.S. Patent Application Publication No. 2012/0258409
However, when a fuel having a high combustion speed is burned, NOx is likely to be generated. When a fuel having a high combustion speed is burned, backfire phenomenon in which flame generated in a combustion chamber is returned to the burner side is likely to occur. Such a fuel is, for example, hydrogen or a gas that contains hydrogen at a high concentration.
In order to overcome these problems, use of a so-called lifted flame is considered. The lifted flame refers to a flame in which a base portion of the flame is formed at a position that is distant from a fuel injection portion in the downstream direction. It is known that a diffusion flame state shifts to the lifted flame state by increasing a flow rate of the fuel. The lifted flame allows reduction of NOx by mixing fuel and air in a space from the fuel injection portion to the base portion of the flame, and lifting of the flame inhibits generation of the backfire phenomenon. A burner having a conventional structure has difficulty in stably forming and maintaining the lifted flame, and is difficult to use for an actual device such as a gas turbine and a boiler in which an operation condition is not always constant.
In order to overcome the aforementioned problem, an object of the present invention is to provide a burner device that can stably form a lifted flame.
In order to attain the aforementioned object, a burner device of the present invention is directed to a burner device for supplying a mixture of a fuel gas and a combustion-supporting gas into a combustion region, and the burner device includes:
a mixing path configured to inject the mixture from a downstream end portion of the mixing path into the combustion region;
a fuel gas injection nozzle configured to inject the fuel gas into the mixing path toward the combustion region; and
a combustion-supporting gas supply swirler configured to inject the combustion-supporting gas from a radially outer side to the mixing path such that at least a part of the combustion-supporting gas collides directly with the fuel gas injected from the fuel gas injection nozzle, in a direction of a tangent line that is tangent to a fuel injection hole of the fuel gas injection nozzle in a cross-sectional view orthogonal to an axis of the burner device.
In this configuration, the combustion-supporting gas is applied directly to the fuel gas injected from the fuel gas injection nozzle, whereby a space, from a portion at which the fuel gas is injected, to the combustion region becomes unstable, and a lifted flame is likely to be formed, and mixture is promoted near the fuel gas injection opening. In addition, swirling flow formed by the combustion-supporting gas supply swirler forms a recirculation region around the burner axis near the outlet of the mixing path to stably maintain the lifted flame.
In the burner device according to one embodiment of the present invention, a width of a combustion-supporting gas flow path of the combustion-supporting gas supply swirler may be gradually reduced from an inlet of the combustion-supporting gas supply swirler toward an outlet thereof. In this configuration, the combustion-supporting gas flow is injected at a high speed from the combustion-supporting gas supply swirler, so that a space from the portion at which the fuel gas is injected, to the combustion region, is more effectively made unstable. Thus, the lifted flame is more likely to be formed.
In the burner device according to one embodiment of the present invention, a diameter of a mixture injection outlet formed in the downstream end portion of the mixing path may be less than a diameter of the outlet of the combustion-supporting gas supply swirler. In this configuration, the flow rate of the mixture of the fuel gas and the combustion-supporting gas increases at the mixture injection outlet. Thus, flame is unlikely to be formed at this portion, and the lifted flame is more likely to be formed. Furthermore, a distance over which the fuel gas and the combustion-supporting gas are mixed can be increased.
The burner device according to one embodiment of the present invention may include a plurality of burner body units BU each including the mixing path, the fuel gas injection nozzle, and the combustion-supporting gas supply swirler. A combustion-supporting gas introduction opening through which the combustion-supporting gas is introduced into the burner device may be disposed on an upstream side of the inlet of the combustion-supporting gas supply swirler of each burner body unit BU in a direction in which the fuel gas is injected. In this configuration, the combustion-supporting gas from the combustion-supporting gas introduction opening does not flow directly into the swirler inlet portion opposing each combustion-supporting gas introduction opening unlike in a case where the combustion-supporting gas introduction opening and the swirler inlet are disposed at the axially same position, and is dispersed while the combustion-supporting gas moves backward, thereby uniformly supplying the combustion-supporting gas to the combustion-supporting gas supply swirlers.
Any combination of at least two constructions, disclosed in the appended claims and/or the specification and/or the accompanying drawings should be construed as included within the scope of the present invention. In particular, any combination of two or more of the appended claims should be equally construed as included within the scope of the present invention.
In any event, the present invention will become more clearly understood from the following description of preferred embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and:
A preferred embodiment of the present invention will be described below with reference to the drawings.
The fuel gas may be, for example, a fuel that has a high combustion speed and a wide range of combustible concentrations. In the present embodiment, a hydrogen-containing gas such as a hydrogen gas is used as the fuel gas. In the present embodiment, an air A is used as the combustion-supporting gas. Other than air, for example, a gas in which the oxygen concentration in the air is adjusted or an exhaust gas may be used as the combustion-supporting gas. In the following description, the fuel gas is represented as “fuel F” and the combustion-supporting gas is represented as “air A”.
The burner device 1 is formed into a substantially cylindrical shape as a whole. In the illustrated example, a casing 7 of the burner device 1 is formed by a substantially disk-shaped burner wall 3 that faces the combustion region R and a burner cylinder 5 having a bottomed cylindrical shape. The burner wall 3 is connected to an opening portion of the burner cylinder 5 by, for example, a not-illustrated bolt. The burner device 1 has a mixing path 9 in which the fuel F and the air A are mixed. The mixture MG is injected into the combustion region R from a mixture injection outlet 11 formed in the downstream end portion of the mixing path 9. The mixing path 9 and the mixture injection outlet 11 are disposed so as to be concentric with the burner device 1. In the illustrated example, a mixture injection hole 13 as a through hole in the axial direction is formed at the center portion of the burner wall 3 of the casing 7. The mixture injection outlet 11 is formed as a downstream end opening of the mixture injection hole 13. In the following description, the combustion region R side (that is, the downstream side in the flow of the mixture MG), in the axis C1 direction, of the burner device 1 may be simply referred to as “backward”, and the opposite side (that is, the upstream side in the flow of the mixture MG) may be simply referred to as “forward”.
The burner device 1 further includes a fuel injection nozzle (fuel gas injection nozzle) 15 for injecting the fuel F into the mixing path 9, and an air supply path (combustion-supporting gas supply path) 17 for supplying the air A to the mixing path 9. The fuel injection nozzle 15 has a fuel injection hole 19 through which the fuel F is injected. The fuel injection hole 19 extends along the axis C1 of the burner device 1. That is, the fuel injection nozzle 15 is configured to inject the fuel F into the mixing path 9 along the axis C1 toward the combustion region R.
More specifically, the air supply path 17 allows the air A to be supplied to the mixing path 9 from the radially outer side of the upstream portion of the mixing path 9. In the illustrated example, the air supply path 17 is formed as an internal space of the burner cylinder 5 of the casing 7. A plurality of air introduction openings 21 are formed in the circumferential wall of the burner cylinder 5 of the casing 7. The air A is introduced from the outside through the air introduction openings 21 into the air supply path 17. An air supply swirler (combustion-supporting gas supply swirler) 23 is disposed at the outlet of the air supply path 17. The air A is supplied, as swirling flow around the axis C1, through the air supply swirler 23 into the mixing path 9. As shown in
In this example, as shown in
More specifically, in the present embodiment, the air supply swirler 23 is configured to inject the air A in the direction of the tangent line T that is tangent to the fuel injection hole 19 in a cross-sectional view orthogonal to the axis C1 of the burner device 1. In the description herein, “is configured to inject the air in the direction of the tangent line that is tangent to the fuel injection hole in a cross-sectional view orthogonal to the axis of the burner device” means that the air supply swirler 23 is positioned and shaped such that the tangent line T that is tangent to the fuel injection hole 19 and parallel to the wall surface 23b on the forward side in the swirling direction S of the air A, among the wall surfaces 23ba and 23ba of the two flow path walls 23b and 23b that extend in respective eccentric directions and that form each swirler flow path 25, passes through an outlet (hereinafter, referred to as “swirler outlet”) 25a of the swirler flow path 25 in the cross-sectional view.
The wall surfaces 23ba and 23ba of the two flow path walls 23b and 23b that form each swirler flow path 25 and extend in respective eccentric directions may not necessarily have a planar shape as shown therein, and may have, for example, a curved shape. When the wall surface 23ba on the forward side in the swirling direction S is formed as a curved surface, the tangent line T that is tangent to the fuel injection hole 19 and parallel to any one point in the downstream-side half portion of the wall surface 23ba is determined as the “tangent line that is tangent to the fuel injection hole and parallel to the wall surface”.
In the present embodiment, the air supply swirler 23 is configured, due to the above-described structure, such that at least a part of the air A injected from each swirler flow path 25 collides directly with the fuel F injected from the fuel injection hole 19.
In the illustrated example, the width of each swirler flow path 25 of to the air supply swirler 23 is gradually reduced from an inlet (hereinafter, referred to as “swirler inlet”) 25b of the swirler flow path 25 toward a swirler outlet 25a.
As shown in
In the burner device 1, shown in
In the present embodiment, particularly, as shown in
In the present embodiment, particularly, as shown in
Next, a burner device 1, shown in
In the illustrated example, the plurality of burner body units BU are disposed in the casing 7 such that an axis C2 of the cylindrical casing 7 and an axis (axis of the fuel injection nozzle 15) C3 of each burner body unit BU are parallel with each other.
More specifically, the internal space of the casing 7 is sectioned by a disk-shaped separation wall 31 into an air introduction chamber 33 on the downstream side (combustion region R side) and a fuel introduction chamber 35 on the upstream side. The plurality of burner body units BU are disposed in the air introduction chamber 33. The fuel F is introduced from the outside into the fuel introduction chamber 35 through a fuel introduction hole 37 formed at the center portion of the bottom wall of the casing 7. The separation wall 31 has a fuel supply hole 39 at a position corresponding to the fuel injection hole 19 of each fuel injection nozzle 15. The fuel F introduced into the fuel introduction chamber 35 is supplied into the fuel injection hole 19 through each fuel supply hole 39. Thus, the fuel F is introduced from the outside into the shared fuel introduction chamber 35 and then supplied into the plurality of fuel injection holes 19, whereby the fuel F is uniformly supplied into the fuel injection holes 19.
The air A is introduced from the outside into the air introduction chamber 33 through the air introduction openings 21 formed in the downstream side portion of the circumferential wall of the casing 7. As shown in
As shown in
More specifically, in the illustrated example, the annular-plate-shaped base portion 23a of the air supply swirler 23 fits into a fitting portion 15a formed in the outer circumferential surface of the downstream end portion of the fuel injection nozzle 15, and each of the air introduction openings 21 is formed at a position, in the axis C2 direction, corresponding to a portion forward of the fitting portion 15a of the fuel injection nozzle 15. When the air introduction openings 21 are thus arranged, the air A introduced from the air introduction opening 21 collides with the fuel injection nozzle 15, and then flows backward and is introduced into the swirler inlet 21. Therefore, during the process, the dispersion of the air A from the air introduction opening 21 progresses, and the air A is very uniformly supplied into the air supply swirlers 23.
Also in the first embodiment shown in
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, various additions, modifications, or deletions may be made without departing from the gist of the invention. Accordingly, such additions, modifications, and deletions are to be construed as included within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-215851 | Nov 2017 | JP | national |
This application is a continuation application, under 35 U.S.C. § 111(a), of international application No. PCT/JP2018/041366, filed Nov. 7, 2018, which claims priority to Japanese patent application No. 2017-215851, filed Nov. 8, 2017, the entire disclosures of all of which are herein incorporated by reference as a part of this application.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2018/041366 | Nov 2018 | US |
| Child | 16868650 | US |
