JP2002206742A - Premixing combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a premixing combustor having a comparatively simple structure which enables combustion of low NOx and low CO by forming a good premixed gas in a wide rage of load operation. SOLUTION: The premixing combustor burns fuel in a combustion chamber by mixing the fuel and air in advance by jetting the fuel to an air passage. The combustor comprises a plurality of swirl vanes 22a, 22b concentrically arranged with an inclination in the radial direction, in the entrance portion of the air passage for generating swirl airflow, and fuel nozzles 6 for jetting fuel from jets 61 which are arranged close to the upstream of the alternately disposed respective vanes 22a, and which are open in the direction of both wing faces of the individual vanes 22a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premixed combustor suitable as a combustor for a gas turbine or the like, and more particularly to a premixed combustor.

[0002]

2. Description of the Related Art A premixed combustor is known as a combustor for supplying a working gas to a gas turbine. In such a premixed combustor, if the premixed gas is heterogeneous, NO
x or CO may be discharged excessively, or the flame may flash back into the premix passage, so consider the arrangement of fuel injection devices and injection devices to form a homogeneous premixed gas. Have been.

[0003] In order to mix fuel and air quickly, it is preferable to arrange a large number of injection nozzles. However, if there are too many injection nozzles, the structure becomes complicated, and at the same time, the injection nozzles block the air passages. Air resistance increases,
It is difficult to achieve the desired air distribution ratio. Also,
For example, when flashback occurs for some reason, if there are many injection nozzles, there is a problem that the flame is held. Reducing the number of injection nozzles simplifies the configuration and reduces manufacturing costs, but it increases the fuel injection amount per injection nozzle, making it difficult to achieve rapid mixing and requiring a large area for premixing. Become.

[0004] The technique of Japanese Patent No. 2794939 is to form a fuel injection nozzle on the wall of a swirler that swirls the air flow when guiding the combustion air into the combustion chamber, whereby the air flow passing through the passage of the swirler is formed. By injecting the fuel toward the fuel, the fuel and the air are quickly mixed in a narrow space.

[0005]

However, according to this technique, when the fuel injection amount is relatively large, such as in a rated operation state, a relatively good mixture is obtained because the fuel injection speed is high. However, when the load is small and the fuel injection amount is small, the injection speed is low, so that the fuel injected from the wall of the swirler is pushed by the airflow and flows along the wall of the swirler, and the fuel is injected. Mixing of air is hindered and a good air-fuel mixture cannot be obtained. Also, forming the fuel injection nozzle on the wall of the swirler complicates the structure of the swirler, increases the manufacturing cost, and has little margin for clogging of the nozzle, which is disadvantageous in terms of maintenance. further,
Even if surging of the gas turbine or the like occurs and the flame flashes back in the premixing passage, a configuration is required in which the flame is not easily held by the injection nozzle or the like.

Therefore, the present invention has a relatively simple structure, forms a good premixed gas over a wide load operating range, and has a low NOx and a low C.
It is an object to provide a premixed combustor capable of realizing O combustion.

[0007]

In order to solve the above-mentioned problems, a premixed combustor according to the present invention mixes fuel and air in advance by injecting fuel into an air passage, and burns the mixture in a combustion chamber. A premixed combustor, a plurality of swirling vanes arranged concentrically and radially inclined at the inlet of the air passage to swirl the air flow, and corresponding to every other swirling blade. And a fuel nozzle that is disposed upstream of the fuel nozzle and that injects fuel from an injection hole that opens in each of the two blade surfaces in the direction of the swirl vane.

By arranging the fuel nozzles in this way,
The fuel injected from each injection hole is distributed to both blade surfaces of the swirling blade. When passing through the swirl vanes,
Although the air flow accelerates, the air and the fuel are rapidly turbulently mixed in the flow region where the velocity gradient is large, so that the premixed air can be formed homogeneously with a relatively simple configuration, and the low NO
x, low CO combustion can be maintained.

[0009] The opening direction of the injection hole may be formed in a direction orthogonal to the inlet direction of the air passage. When the injection hole is formed at this position, one of the openings corresponding to each of the wing surfaces of the swirl vanes is located upstream of the fuel nozzle in the air flow direction, and the other is located downstream. As a result, when the load is small and the fuel supply amount is small, relatively high air pressure is applied to the injection holes located on the upstream side, while relatively low air pressure is applied to the injection holes located on the downstream side. The injection amount from the located injection hole relatively increases. As a result, the amount of fuel injected to the downstream side where the turbulence is large relatively increases, whereby the effect of promoting the mixing is obtained.

Alternatively, a premixed combustor according to the present invention comprises:
Assuming that the distance from the inlet of the air passage to the fuel injection position is D, and the height of the air passage is H, a fuel nozzle having an injection hole is provided at a position satisfying the relationship of H ≦ D <2H. And

At a position satisfying the above relationship from the entrance of the air passage, the air flow is accelerating and flows.
By injecting fuel into the accelerated airflow, mixing of fuel and air can be promoted. Further, since the injected fuel does not leak from the inlet side of the air passage to the outside, it is possible to appropriately maintain the fuel supply amount to each stage when performing stepwise combustion, and NOx and low CO combustion can be maintained. Further, even if a flashback occurs, the flame is safe because it is not retained in the high flow velocity region.

A plurality of air passages may be provided, each having a fuel nozzle arranged therein, and each fuel nozzle may be arranged close to an upstream extension of a swirling vane arranged in each air passage. . When a plurality of stages of premixed air passages are provided, it is possible to form a good premixed air at each stage with a relatively simple structure.

In this case, the fuel nozzle arranged in one of the air passage for the primary premixed fuel and the air passage for the secondary premixed fuel is arranged between the fuel nozzles arranged on the other as viewed from the axial center. Is preferred. By arranging the fuel nozzles alternately with respect to the axis center in this way,
The flow of air flowing into each air passage is less likely to be obstructed by the fuel nozzle, and the flow of air can be optimized, and the air flows smoothly without any stagnation region. In addition, even if an uneven distribution is formed in each premixed gas, the effect of reducing the uneven fuel concentration in the circumferential direction between the first order and the second order can be obtained.

[0014]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In order to facilitate understanding of the description, the same constituent elements are denoted by the same reference numerals as much as possible in each drawing, and redundant description will be omitted.

FIG. 1 is a longitudinal sectional view showing a first preferred embodiment of a premixed combustor according to the present invention, FIG. 2 is a sectional view taken along the line II-II of this combustor, and FIG. FIG. 3 is an enlarged view of a combustion nozzle and a swirl vane portion.

The combustor 100 is a can-type combustor having a substantially cylindrical inner cylinder 2 disposed inside a substantially cylindrical outer cylinder 1.
Combustion air is introduced from the right end of the drawing to the space 50 between the outer cylinder 1 and the inner cylinder 2, the flow is reversed near the other end and introduced into the inner cylinder 2 together with fuel, and after combustion, from the right end It is a backflow type combustor that allows it to flow out.

In FIG. 1, a fuel supply pipe of three systems is connected to a member 3 constituting the left end in the outer cylinder 2 and communicates with a pilot nozzle 4, a primary fuel nozzle 5, and a secondary fuel nozzle 6, respectively. . Here, the pilot nozzle 4 has an outlet 41 in the center of the inner cylinder 2 on the upstream side (pointing to the left side in the figure), and an ignition device 42 is arranged near the outlet 41. The downstream side is the pilot combustion section 43. A swirling blade 44 is disposed in a passage for guiding air to the pilot combustion section 43.

The primary fuel nozzle 5 is a pilot nozzle 4
A plurality of swirling vanes 12 are arranged downstream of the inlet 11 in an annular passage (hereinafter, referred to as a primary premixing passage) 13 provided on the outer periphery of the nozzle. The outlet 14 of the primary premix passage 13 is disposed downstream of the outlet 41 of the pilot nozzle 4 in the flow direction. A portion near the downstream of the outlet 14 is a primary premixed combustion chamber 15.

A plurality of secondary fuel nozzles 6 are arranged near an inlet 21 in an annular passage (hereinafter, referred to as a secondary premixing passage) 23 provided further around the primary fuel nozzle 5. Downstream, a plurality of swirling vanes 22 are arranged. The outlet 24 of the secondary premix passage 23 is disposed further downstream in the flow direction than the outlet 14 of the primary premix passage 13. The vicinity of the downstream of the outlet 24 is the secondary premixed combustion chamber 2
It becomes 5.

Hereinafter, the arrangement of the secondary fuel nozzle 6 and the swirl vane 22 will be described with reference to FIG. 2, but the same relationship holds for the arrangement of the primary fuel nozzle 5 and the swirl vane 12.

The swirl vanes 22 each include eight kinds of swirl vanes 22a and 22b having different lengths, and short swirl vanes 22a are arranged at equal intervals between the long swirl vanes 22b. . Each swirl blade 22a, 2
2b is arranged in a disk-shaped swirl part of the secondary premixing passage 23, and is arranged to be inclined with respect to the radial direction;
The radial position of the rear end (the end on the center side of the disk) is the same. Therefore, the tip of the long swirling blade 22b is located closer to the inlet 21 of the secondary premixing passage 23 in the radial direction than the tip of the short swirling blade 22a.

Each of the secondary fuel nozzles 6 has a swirl vane 22
a is extended close to the inlet side, and is disposed close to the position. An injection hole 61 is provided at a position 180 degrees opposite to the side surface of the secondary fuel nozzle 6, and the fuel sent through the central hole 60 of the tubular fuel nozzle 6 is supplied to the secondary premix passage 23.
It has the function of injecting inside. Each of these injection holes 61 is opened in a direction orthogonal to the radial direction.

Here, the secondary fuel at the center of the secondary fuel nozzle 6 is
Distance D from inlet 21 of mixing passage 23_TwoIs the second premix
The height of the entrance 21 of the passage 23 is H_TwoThen, H_Two≤D_Two
<2H _TwoAre located in a position that satisfies the relationship
preferable. Near the entrance 21 of the secondary premixing passage 23,
The flow of air coming in through road 50 is still uneven
Yes, the flow is not stable, and it erupted
Since fuel may leak from the inlet 21,
In order to achieve mixing, H_TwoAbove
It is preferable to inject fuel at a position in the mixing passage 23.
Good. Furthermore, even if the flame flashes back due to surging, etc.
However, since the injection nozzle is located in the high flow velocity area,
It is not held and troubles such as burning can be prevented. Meanwhile, fuel
Injection position 2H from inlet 23_TwoIf you go further back, fuel and
In addition to shortening the air mixing space,
Good mixing because the mixing of air in
Is difficult.

In the present embodiment, the air introduced into the secondary premixing passage 23 from the passage 50 is accelerated by flowing along eight long swirling vanes 22b disposed near the inlet 21 and is accelerated. On the way, fuel is injected into the air flow from the injection hole 61 of the secondary fuel nozzle 6. The airflow guided to the left and right of the short swirl vanes 22a disposed downstream of the secondary fuel nozzle 6 is further accelerated, so that large velocity gradients and turbulence are formed on the left and right of the swirl vanes 22a. Utilizing this turbulence, mixing of fuel and air can be promoted.

Here, of the injection holes 61, the injection hole 61L disposed on the left side in FIG. 3 is located on the upstream side in the air flow direction as viewed from the fuel nozzle 6, and the injection hole 61R disposed on the right side. Will be located downstream. As a result, when the load is small and the fuel supply amount is small, a relatively high air pressure is applied to the injection hole 61L, and a relatively low air pressure is applied to the injection hole 61R, so that the injection amount from the injection hole 61R is relatively small. To increase. As a result, the amount of fuel injected to the downstream side where the turbulence is large relatively increases, whereby the effect of promoting the mixing is obtained. Further, the fuel nozzle 6 is turned by the swirling blade 22d.
The fuel nozzle 6
There is also an effect that the flame is hardly held.

The premixed gas thus well mixed is guided to the secondary premixed combustion chamber 25 in the inner cylinder 2, and the pilot diffusion formed in the pilot combustion section 43 and the primary premixed combustion chamber 15, respectively. The flame is burned by the primary premixed flame to form a secondary premixed flame.

According to the present invention, since the premixed gas can be homogeneously mixed in a relatively compact and short space in a wide operating range, a premixed gas having a desired equivalence ratio can be reliably obtained, and a wide mixture can be obtained. Low NOx and low CO combustion can be realized in the operating range.

Here, the primary fuel nozzle 5 and the secondary fuel nozzle 6 are respectively located between the other nozzles when viewed from the axial center.
That is, it is preferable that they are alternately arranged in the circumferential direction. With this arrangement, even if a non-uniform distribution of the equivalence ratio occurs in the circumferential direction in each of the primary premixed gas and the secondary premixed gas, the concentration position of the fuel concentration can be shifted in the circumferential direction. The effect of uniformity can be reduced.

In the above description, the embodiment in which the premixed gas is burned in two stages has been described. However, the premixed gas may be burned in three or more stages. However, the present invention can be suitably applied.

Next, a second embodiment of the premixed combustor according to the present invention will be described. The second embodiment has the same basic configuration as the first embodiment shown in FIG.
The arrangement of the fuel nozzle and the swirl vanes is different from the first embodiment.

FIG. 4 is a cross-sectional view of the disk portion of the secondary premixing passage 23 in the second embodiment, and FIG. 5 is an enlarged view showing the relationship between the nozzle and the swirl vanes.
Corresponding to

In the present embodiment, the swirl vanes 22
It is composed of only 16 short rotating blades 22a of the same shape. They are arranged at equal intervals inclining with respect to these radial directions, and their front and rear ends are arranged so that their radial positions are the same.

The secondary fuel nozzles 6 are arranged close to each other at positions where every other swirl blade 22a extends toward the inlet side. On the side surface of the secondary fuel nozzle 6, there are provided injection holes 63 that open toward the left and right sides of the corresponding swirling blade 22a.

In this embodiment, the secondary premix passage 2
Since the swirl vanes 22a are not extended to the entrance of No. 3,
The air flow in the secondary premixing passage 23 is less affected by fluctuations and deviations of the air flow in the outer space. Further, by making the swirling blades 22a short, the manufacturing cost can be further reduced. By injecting fuel toward the left and right sides of the swirling blade 22a from the injection holes 62 opened to the left and right sides of the swirling blade 22a, a large velocity gradient and turbulence formed on the left and right sides of the swirling blade 22a are utilized. To promote mixing of the fuel and air.

[0035]

As described above, according to the present invention,
Since a homogeneous premixed gas can be obtained in a wide load range with a simple configuration, low NOx and low CO combustion can be realized. Also,
Since the configuration is simple, the production is easy, the production cost is reduced, and the maintainability is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a premixed combustor according to the present invention.

FIG. 2 is a sectional view of an air passage according to the first embodiment.

FIG. 3 is a partially enlarged view of FIG. 2;

FIG. 4 is a sectional view of an air passage according to a second embodiment.

FIG. 5 is a partially enlarged view of FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer cylinder, 2 ... Inner cylinder, 5 ... Primary fuel nozzle, 6 ... Secondary fuel nozzle, 12, 22 ... Swirl vane, 13 ... Primary premix passage, 23 ... Secondary premix passage, 61, 63 ... Injection Hole 100 ...
Premixed combustor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Unegami 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Masakazu Hasegawa 1 Motomachi, Toyota City, Aichi Prefecture Toyota Motor Corporation Motomachi Plant F term (reference) 3K065 TA01 TA04 TB01 TC08 TD02 TF03 TJ03 TJ06 TM05

Claims (5)

[Claims] 1. A premixed combustor in which fuel is preliminarily mixed by injecting fuel into an air passage and then burned in a combustion chamber, wherein an inlet of the air passage is concentrically and radially inclined. A plurality of swirling vanes arranged to swirl the air flow, and jets arranged upstream of the swirling vanes corresponding to every other swirling vanes and opened corresponding to both blade surface directions of the swirling vanes. A fuel nozzle for injecting fuel from the hole; 2. The premix combustor according to claim 1, wherein an opening direction of the injection hole is formed in a direction orthogonal to an inlet direction of the air passage. 3. A premixed combustor in which fuel is previously mixed by injecting the fuel into an air passage and then burned in a combustion chamber, wherein a distance from an inlet of the air passage to a fuel injection position is D, Assuming that the height of the passage is H, a premixed combustor provided with a fuel nozzle having an injection hole at a position satisfying a relationship of H ≦ D <2H. 4. A fuel cell system comprising: a plurality of air passages; a fuel nozzle disposed in each of the air passages, wherein each fuel nozzle is disposed adjacent to an upstream extension of a swirling vane disposed in each air passage; The premixed combustor according to claim 1. 5. A fuel nozzle disposed in one of an air passage for a primary premixed fuel and an air passage for a secondary premixed fuel,
5. The premixed combustor according to claim 4, wherein the premixed combustor is disposed between fuel nozzles disposed on the other side as viewed from the center of the shaft.