JPH0647954B2 - Gas turbine premixer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a premixer for a gas turbine, and more particularly to a premixer for a high temperature gas turbine.

[Conventional technology]

A conventional premixer for a gas turbine is disclosed in JP-A-61-221247.
As described in No. 3, the fuel is ejected from rod-shaped nozzles arranged in an annular shape. The fuel ejected from this nozzle is gasified and mixed with air for combustion, and at the outlet of the premixer, the fuel is mixed with air in a relatively good state and flows out as a premixed gas. .

[Problems to be Solved by the Invention]

In this conventional example, when the capacity of the premixer is increased in order to reduce NOx, nonuniformity of the air flow velocity in the radial direction occurs at the outlet of the premixer, which causes nonuniform fuel concentration. . Also, if the fuel flow rate is reduced during low-load operation of the gas turbine, there is a mechanical limit in reducing the air amount to match it, so the fuel-air ratio will inevitably decrease, and air will The premixed fire becomes unstable because it becomes too much, and the worst situation such as the extinguishment of the fire is likely to occur.

The object of the present invention is to eliminate the above-mentioned drawbacks in the prior art, and appropriately perform the fuel-air ratio control at the premixer outlet,
It is an object of the present invention to provide a premixer for a gas turbine that can make the air flow velocity distribution and the fuel concentration distribution in the radial direction uniform and optimize them.

[Means for Solving the Problems]

A premixer for a gas turbine according to the present invention has a double cylinder shape having an inner cylinder and an outer cylinder, and ejects fuel into combustion air flowing in a flow path between the inner cylinder and the outer cylinder. Then, a plurality of fuel injection nozzles arranged at intervals in the radial direction and the fuel injection amount from these fuel injection nozzles are controlled respectively. And means.

[Action]

Since the premixer for the gas turbine according to the present invention has the above-described structure, the fuel injection amount from the fuel injection nozzles arranged at intervals in the radial direction is appropriately controlled, and the premixer at the outlet of the premixer is controlled. It is possible to appropriately adjust the fuel concentration distribution in the radial direction. As a result, the fuel concentration distribution in the radial direction at the outlet of the premixer can be adjusted so as to be uniform at 100% load, and when the fire is transferred from the pilot fire to the premixed air, It is possible to easily transfer the fire by increasing the fuel concentration on the fire side. Also, if the fuel concentration at the outlet of the premixer is made uniform during partial load operation, the fuel concentration may become too small and combustion of the premixed mixture may become difficult, but in such a case, the fuel concentration is locally high. It is possible to form a portion to enable stable premixed gas combustion.

Thus, according to the present invention, the combustion of the premixed gas produced by the premixer can be stably performed over the entire load zone of the gas turbine, and the generation of NOx can be suppressed to a low level.

〔Example〕

First, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

This premixer is in the form of a double cylinder having an inner cylinder 1 and an outer cylinder 2, and has a skirt portion 3 and a cylindrical portion 4 extending in the radial direction. A slightly twisted vane 5 is provided between the outer tube 2 and the outer tube 2 so as to be circumferentially spaced apart from each other to form a plurality of slightly twisted flow paths 6. Air has a structure in which air flows inward from the skirt portion 3 in the radial direction and flows out through the flow path 6. That is, the air flowing in from the skirt portion 3 in the radial direction flows through the passage 6 formed by the inner cylinder 1, the outer cylinder 2 and the vane 5.

Between the inner cylinder 1 and the outer cylinder 2, two annular fuel injection rings 7A and 7B, which are an inner side and an outer side, are provided around the central axis of the premixer. These fuel injection rings 7A, 7B
As shown in FIG. 3, has fuel injection holes 8A, 8B, 8C for ejecting fuel in the forward and vertical directions.

The amount of outflow of fuel in the forward and vertical directions from these fuel injection rings 7A, 7B is such that the fuel concentration distribution in the radial direction at the outlet of the premixer is most appropriate in a specific state. , 7B fuel injection holes 8A, 8
B and 8C dimensions can be selected and provided.
It is also possible to provide the fuel injection holes 8A, 8B, 8C in directions other than the vertically upward, vertically downward, and axially forward directions shown in the drawing. In this way, the radial fuel concentration distribution at the outlet of the premixer can be optimized in a particular situation.

Further, as shown in FIG. 2, each fuel injection ring 7A, 7B has an adjusting valve 9 for independently adjusting the respective fuel injection amount.
A and 9B are provided so that the fuel injection amounts of the fuel injection rings 7A and 7B can be controlled separately. With this structure, the fuel concentration distribution in the radial direction at the outlet of the premixer can be freely controlled.

It should be noted that the fuel injection is not limited to the illustrated fuel injection nozzles 7A and 7B, and as shown in FIG. 2, a plurality of rod-shaped nozzles 20A and 20B supported by the inner cylinder 1 and provided in the axial direction may be used. Directionally spaced and circumferentially annularly arranged, with at least the inner nozzle 20A and the outer nozzle 20B being provided with separate regulating valves 21A, 21B, whereby radial fuel concentration at the outlet of the premixer is provided. The distribution can be controlled freely. That is, if necessary, the fuel injection ring 7
It is possible to use both A, 7B and the rod-shaped nozzles 20A, 20B, or only one of them.

Further, the fuel injection is not limited to the fuel injection rings 7A and 7B and the rod-shaped nozzles 20A and 20B shown in FIGS. 1 to 3, but the fuel is injected into the inner cylinder 1 and the outer cylinder 2 respectively as shown in FIG. The jet nozzle rings 30A and 30B may be provided. Each of the nozzle rings 30A, 30B has a plurality of fuel ejection holes 31A, 31B formed in the inner cylinder 1 and the outer cylinder 2 so as to be circumferentially separated from each other, and these fuel ejection holes 31A, 3B.
An annular member 33A, which surrounds 1B and internally forms passages 32A, 32B communicating with the fuel ejection holes 31A, 31B,
33B and can be controlled separately by adjusting valves 34A and 34B, respectively.

In the embodiment shown in FIG. 5, in addition to the nozzle rings 30A and 30B shown in FIG. 4, a fuel injection ring 7C as shown in FIG. 2 and a regulating valve 9C associated therewith are provided. Therefore, the fuel concentration distributions on the inner peripheral side, the outer peripheral side of the passage 6 and the intermediate portion thereof can be independently adjusted.

As described above, in the present invention, the fuel injection ring 7A,
7B and 7C, rod-shaped nozzles 20A and 20B, and inner cylinder 1
And an annular fuel injection nozzle 30 formed in the outer cylinder 2
It is possible to use A and 30B independently and simultaneously use them in various combinations.

In such a premixer, as shown in FIGS. 1 and 2, the inflow direction of the air in the skirt 3 is the radial direction, and the cylindrical portion 4 forming the outlet is in the axial direction. The air velocity at the outlet of the mixer may not be uniform in the radial direction. That is, when the air flowing inward in the radial direction collides with the inner cylinder 1 and the air exits from the outlet of the premixer, the flow velocity of the outer peripheral side, that is, the portion along the outer cylinder 2 tends to increase. In such a case, the two fuel injection rings 7A and 7B
The fuel injection amount from the outer fuel injection ring 7B can be made larger than that from the inner fuel injection ring 7A to make the fuel injection concentration from the outlet of the premixer uniform.

Further, the axial length of the fuel injection rings 7A, 7B is set to the second
By properly setting as shown in the figure, it is possible to also serve as a straightening plate for causing the fuel injection rings 7A and 7B to straighten the air flowing in the premixer. This effect makes the air velocity distribution at the outlet of the premixer more uniform and the fuel concentration distribution at the outlet of the premixer more uniform.

As a means for obtaining the rectifying effect, rectifying plates 22A, 22B can be provided at the same radial positions as the fuel injection rings 7A, 7B as shown in FIGS. 1 and 2. Such a rectifying plate is not limited to the position shown in the drawing, but may be the ring 7A and the inner cylinder 1.
Between the ring 7B and the outer cylinder 2, and between the ring 7A,
It is also possible to provide between 7B comrades.

Usually, since combustion of the premixed gas obtained by the premixer is generally unstable, a pilot fire (not shown) is usually provided on the inner diameter side of the premixer, that is, inside the inner cylinder 1. ) Is provided. Normally, a diffusion combustion fire with stable combustion is used as the pilot fire. Then, a pilot fire is ignited and operated during low-load operation of the gas turbine, and when the load of the gas turbine reaches a certain load, this pilot fire is used to ignite and operate premixed gas at the outlet of the premixer. It operates by increasing the premixed combustion amount until full load operation.

Therefore, the premixer according to the present invention can take the following methods.

First, a pilot fire is ignited, and then, when the premixed mixture is ignited from the premixer, the fuel concentration on the pilot fire side, that is, on the inner diameter side of the premixed mixture is made higher than that on the outside to premix. The ignition of the vessel can be facilitated. This can be achieved by making the fuel injection amount from the fuel injection ring 7A on the inner cylinder side larger than the fuel injection amount from the fuel injection ring 7B on the outer cylinder side in FIG. Furthermore,
At the maximum load, the fuel injection amount from the outer cylinder side fuel injection ring 7B and the fuel injection amount from the inner cylinder side fuel injection ring 7A are controlled so that the fuel concentration at the outlet of the premixer becomes uniform in the radial direction. To do.

Further, in the premixer to which the present invention relates, the energy supplied to the gas turbine extends over a wide range, so that the amount of fuel supplied is wide, and in addition, in order to perform stable combustion in the premixer, the amount of fuel supplied and the amount of supply The ratio with the amount of air must be kept within a certain range. For this purpose, the fourth
As shown in the figure, a ring-shaped air flow rate adjusting ring 23 is provided at the air inlet of the premixer, and this is slid in the axial direction as shown by the arrow to make the area of the air inlet variable, and The air inflow rate can be adjusted. In this case, when the load of the gas turbine is low, the air adjusting ring 23 is moved as shown in FIG. 4 to reduce the area of the air inlet to the premixer, so that the air flows only along the inner cylinder 1 and the premixer is operated. The air flow velocity on the inner cylinder side of the outlet becomes faster. In such a case, of the two fuel ejection rings 7A and 7B, the fuel ejection amount from the fuel ejection ring 7A on the inner cylinder side can be increased to maintain an appropriate fuel concentration at the outlet of the premixer. it can.
Therefore, when transferring the fire from the pilot fire to the premixer at the exit of the premixer, the gas turbine load is low, so the premixer is used in response to the small fuel supply to the premixer. It is also useful in realizing the requirement that the ratio of the amount of fuel to the amount of air in the premixer be kept within a certain range by reducing the amount of air flowing into the device.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a premixer having the required radial flow velocity distribution and fuel concentration distribution at the outlet of the premixer. Therefore, when the load is high, the distribution is made uniform, and when the fire transfer from the pilot fire to the premixed air is performed, the fuel concentration of the premixed air on the inner cylinder side is increased to facilitate the fire transfer, When the load is low, the fuel concentration distribution is appropriately adjusted so as to stabilize the premixed mixture combustion, and the premixed mixture combustion can be performed satisfactorily and stably over the entire load zone of the gas turbine.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a premixer according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view showing an essential part of the premixer shown in FIG. 1, and FIG. 2 is an enlarged cross-sectional view of the fuel injection nozzle ring shown in FIG. 2, FIG. 4 is a cross-sectional view showing a main part of another embodiment of the present invention, and FIG. 5 is a cross-sectional view of yet another embodiment of the present invention. FIG. 6 is a sectional view showing a portion, and FIG. 6 is a sectional view showing a main portion of still another embodiment of the present invention having an air flow rate adjusting ring. 1 ... Inner cylinder, 2 ... Outer cylinder, 7a, 7b ... Fuel injection nozzle, 9a, 9b ... Regulator valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Sato 3-1-1, Saiwaicho, Hitachi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Osamu Arai 3-1-1, Saiwaicho, Hitachi, Ibaraki No. 1 Hitachi Ltd., Hitachi Works (56) References JP-A-55-155118 (JP, A) JP-A-61-22127 (JP, A) JP-A-1-273918 (JP, A) Kai 62-267529 (JP, A) Japanese Patent Publication 1-43135 (JP, B2)

Claims (3)

[Claims] Claim: What is claimed is: 1. A double cylinder having an inner cylinder and an outer cylinder, wherein the fuel is jetted into the combustion air flowing in the flow path between the inner cylinder and the outer cylinder to form the fuel and the air. In a premixer of a gas turbine for premixing, the first fuel injection nozzles arranged at intervals in the radial direction for ejecting the fuel into the flow passage, and the inner cylinder and the outer cylinder are formed. A premixer for a gas turbine, comprising: a second fuel ejection nozzle having a jet outlet and means for controlling the amount of fuel ejected from the fuel ejection nozzle. 2. A double cylinder having an inner cylinder and an outer cylinder, wherein the fuel is jetted into the combustion air flowing in the flow path between the inner cylinder and the outer cylinder to form the fuel and the air. In a premixer of a gas turbine for premixing, a fuel injection nozzle having an injection port, which is arranged at intervals in a radial direction in order to inject the fuel into the flow path,
A premixer for a gas turbine, comprising: a unit for controlling an amount of fuel ejected from the fuel ejection nozzle, wherein the fuel ejection direction from the ejection port is a plurality of different directions. 3. A double cylinder having an inner cylinder and an outer cylinder, wherein the fuel is jetted into the combustion air flowing in the flow path between the inner cylinder and the outer cylinder to form the fuel and the air. In a premixer of a gas turbine for premixing, the rod-shaped nozzles are arranged at intervals in a radial direction and are distributed in a circumferential direction in order to eject the fuel into the flow passage, A fuel jet nozzle having an outlet, and means for controlling the amount of fuel jetted from the fuel jet nozzle, wherein the fuel jet direction from the jet outlet is a plurality of different directions. Mixer.