JPS58210413A - Combustor for gas turbine - Google Patents

Abstract

PURPOSE:To reduce the production of NOX, by a method wherein, a head part of an inner cylinder is so constituted in a double type as to form a small auxiliary combustion chamber therein, while a large main combustion chamber is formed at the rear, and air holes in the inner and the outer peripheral cylinder of the auxiliary combustion chamber are aligned on the same center line. CONSTITUTION:The air 200 is distributedly fed to swirlers 101, 102, and 105, a scoop hole 103, and circular holes 104, 106, and 107. A fuel 300 is fed through a fuel nozzle 7, and the effects of high speed spiral air current 201, 202, and 205 produced by the swirlers 101, 102, and 105, an air current 203 by the scoop hole 103, and an air current 204 by the circular hole 104 are increased at the inside of an auxiliary combustion chamber 5 through the provision of air holes 108 of an inner cylinder 3 on the center lines of the swirlers 102, 105, the scoop hole 103, and circular hole 104, all formed within a cylinder 4 to produce a stable primary combustion flame. A secondary combustion flame is formed by a rapid combustion produced as a result of the reduction of a flow velocity at the expanded outlet part of a chamber 5 and by the action of an air current produced by the circular hole 106. This permits the improvement of a dilution ratio of fuel.

Description

[Detailed Description of the Invention] This invention relates to a combustor for a gas turbine, and in particular, the structure of a can-type combustor using combustion with an auxiliary combustion chamber, which is suitable for reducing nitrogen oxides (NOX) generated in the combustor. Regarding.

Air pollutants emitted from gas turbines today are
OX has become a very serious problem, and vigorous efforts are being made to develop technologies to reduce it. Conventionally, gas turbines have been made to have low NOx, and water or steam has been directly injected into the combustor. A method of lowering the flame temperature has been put into practical use. According to this method, it is possible to reduce NOx by about 80% when no countermeasures are taken. However, this method has the drawback of reducing its effectiveness, and with the recent trend toward energy conservation, alternative low NOx reduction methods have been developed. For this reason, it has become necessary to develop a 1ffi NOX combustor based on low-temperature combustion control, which is the key to reducing NOx.

In order to meet the above requirements, the present inventors conducted various prototype tests and proposed the low NOx combustor shown in FIG. 1. This low NOx combustor has a combustor inner cylinder 3 placed in a space sealed by a combustor outer cylinder 1 and a combustor cover 2, a small-diameter auxiliary combustion chamber 5 at the head of the inner cylinder 3, and a small-diameter auxiliary combustion chamber 5 at the rear. Large diameter main combustion chamber 6
The combustion chamber is provided with an auxiliary combustion chamber cylinder 4 for stratifying the combustion chamber. That is, the head part Ifi of the inner cylinder 3 has a double cylindrical structure, thereby reinforcing the auxiliary combustion chamber cylinder 4, which has a small diameter. Also,
A fuel nozzle 7 with the cover 2 as a mounting seat is attached in the internal space of the auxiliary combustion chamber 5, and a swirler 101 for primary combustion air is provided around the outer periphery of the nozzle 7. Furthermore, there are four cylinders in the sub-combustion chamber, a swirler 102 for primary combustion air, and one
o5, a scoop hole 103, a circular hole 104, and one inner cylinder 3 has a circular hole 106 for secondary combustion air, a circular hole 107 for dilution air, and a circular hole for supplying air to the sub-combustion chamber 5. A plurality of holes 108 are each provided along with cooling air holes (not shown).

With the above configuration, the supply air 200 from the air compressor 8
The swirler 10 passes through the annular space between the outer cylinder 1 and the inner cylinder 3.
1, 102 and 105, scoop hole 103, circular hole 104
, 106 and 107, respectively. on the other hand,
A fuel 300 in the form of liquid or gas is supplied from the fuel nozzle 7 . Inside these 300 fuel sub-combustion chambers 5, high-speed swirling air flows 201, 202, and 205 are created by swirlers 101, 102, and 105, air flows 203 toward the shaft center by scoop holes 103, and circular holes 104. Due to the effects of the air flow 204 and the like, a stable primary combustion flame is formed even though the fuel is in a lean state. The primary combustion flame thus obtained has a low flow velocity at the enlarged outlet of the sub-combustion chamber 5, and due to the action of the air flow through the circular hole 106, a secondary combustion flame is formed by rapid combustion. Thereafter, the temperature of the combustion gas is reduced to a predetermined temperature by the air flow 207 from the circular hole 107, and the obtained combustion gas 208 is transferred to the turbine 9.
used as driving force.

As mentioned above, the low NOX combustor uses a vortex flow system, so combustion stability is better than other types, and as a result, the fuel lean ratio can be increased, making it possible to significantly reduce NOX. It is.

However, since the amount of air supplied to the auxiliary combustion chamber 5 is extremely large, and the pressure difference between the inside and outside is smaller than that of the main combustion chamber 6, the opening area of each air hole in the auxiliary combustion chamber cylinder 4 is extremely large. becomes. From the viewpoint of strength, it is preferable that the opening area of each air hole is small, and it is important to reduce the ventilation loss of each air hole of the sub-combustion chamber 5, which has a double structure. Further, it is required that the air flow from each air hole is axially symmetrical and that there is no imbalance in the combustion gas flow.

The key point of the present invention is that the inner cylinder 3 and Ill and the combustion chamber cylinder 4 are connected to each other.
In the sub-combustion chamber 5 having a heavy structure, swirlers 102 and The air 108f of the inner cylinder 3 is provided on the center line of the 105 scoop hole 103 and the circular hole 104.

FIGS. 2 and 3 show an embodiment of the present invention, and correspond to the cross sections 1--2 and 1it-1 in FIG. 1, respectively.

A plurality of scoop holes 103 and a circular hole 1 of the sub-combustion chamber cylinder 4
04, an attached circular hole 108 of the inner cylinder 3 having a larger diameter than these air holes is provided on its center line. With this configuration, the dynamic pressure of the air flow flowing in from the attached circular hole 108 of the inner cylinder 3 can be used as is, so the ventilation loss between the scoop hole 103 and the circular hole 108, and between the circular hole 104 and the circular hole 108 is reduced. In the corner, also from the circular hole 108 to the scoop hole 1
03, since the air flow goes straight from the circular hole 108 to the circular hole 104, it is axially symmetrical with respect to the inflow into the sub-combustion chamber 5.

On the other hand, if the swirlers 102 and 105 are also provided with circular holes 108 on their center lines, the same effect as described above can be expected.

According to the present invention, ventilation loss is small, the air holes in the inner wall can be made small in diameter, and the strength of the sub-combustion chamber is increased.

Moreover, effects such as axially symmetric air inflow and unbalanced combustion gas can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a gas turbine combustor according to the present invention;
Figures 2 and 3 are the ■-■ arrow view and ■ of Figure 1, respectively.
−■ It is a sectional view taken along the arrow. Figure 2nd part

Claims (1)

[Claims] 1. Equipped with a double cylinder consisting of an inner cylinder and an outer cylinder, the annular space between the inner cylinder and the outer cylinder is used as an air circulation part, and the head of the inner cylinder is used as a sub-combustion chamber with a small diameter. In a gas turbine combustor that has a double cylinder with a fuel nozzle at the side end and a main combustion chamber with a large diameter at the rear, the air holes of the inner cylinder and the outer cylinder of the sub-combustion chamber are in the same center. A gas turbine combustor characterized in that it is configured to be arranged on a line.