JPH0668375B2 - Gas turbine two-stage combustor operating method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for operating a two-stage combustor for a gas turbine after charging secondary combustion fuel.

[Conventional technology]

If the NOx content in the gas turbine exhaust gas is to be significantly reduced, the diffusion combustion method using the single-nozzle method according to the related art cannot be applied. Therefore, a two-stage combustion technique that uses premixed combustion together and has two fuel paths is applied. As shown in Japanese Patent Application No. 55-115991, this is equipped with a head combustion chamber that burns the primary fuel and a rear combustion chamber that burns the secondary fuel in the high load zone downstream of this combustion chamber. Only the primary fuel is used up to the low load zone up to 25% load, and the secondary fuel is used together in the higher load zone. In the second stage combustion, the flame is transferred from the first stage flame as an ignition source. In the conventional example (Sho 55-115991), the second stage fuel is added to the first stage fuel to increase the load. Even if the second stage fuel is added, a fire transfer to the second stage occurs. If it is not, or if the second-stage combustion is misfired during operation, only the first-stage combustion is occurring. In such a case, the second-stage fuel is not burned and is discharged as fuel. ,
The efficiency will be greatly reduced. In addition, there are drawbacks such as a sudden change in the gas turbine load and an inability to increase the gas turbine load. Further, when the second stage combustion misfires, a rapid gas temperature drop occurs, which causes a rapid thermal shock to the combustor forming the combustion gas passage, the transition piece, and the turbine blade. It will lead to a serious accident leading to damage. Further, when the second stage combustion is started, the second stage fuel is added to the first stage combustion in addition to the first stage combustion, so that the turbine load is rapidly increased when the second stage combustion is started. Various drawbacks occur.

[Problems to be Solved by the Invention] As described above, in the prior art, no consideration is given to when the second-stage combustion flame ignites, does not ignite, and misfires during loading. As a result, the above-mentioned problems (decrease in efficiency, sudden change in load, inability to increase load, thermal shock) are caused.

The present invention provides a method for operating a two-stage combustor capable of preventing the occurrence of the above-mentioned problems by controlling the fuel and air adapted to the situation of the second-stage flame generated by the secondary combustion fuel. The purpose is to

[Means for solving problems]

In order to achieve the above object, the operating method according to the first aspect of the present invention provides a primary combustion fuel nozzle and a head combustion chamber on the upstream side of the combustion chamber and a secondary combustion fuel nozzle on the downstream side thereof. And a rear combustion chamber, and is applied to the operation of a two-stage combustor for a gas turbine, which is provided with a secondary combustion air flow rate adjusting means, to generate a second stage flame of the secondary combustion performed in the rear combustion chamber. At least the control of the primary combustion fuel flow rate and the secondary combustion fuel flow rate, and the combustion air flow rate control based on the output signal of the flame detection means after the secondary combustion fuel injection is provided. One of the controls is performed.

In addition, in the operating method according to the second aspect of the present invention, when the second stage flame is ignited and then misfired, the fuel for the second combustion is increased and the fuel for the first combustion is decreased to burn the second stage flame. The operation method according to the third aspect of the present invention promotes transfer, and when the second stage flame is ignited and then misfires, increases the secondary combustion air flow rate to promote the transfer to the second stage flame. is there.

[Action]

The above operating method relates to an operation technique after the fuel for secondary combustion is charged. Then, the injection of the secondary combustion fuel is performed as follows. That is, at the time of charging the second stage fuel, the operation of charging the second stage fuel for the secondary combustion is performed while reducing the first stage fuel for the one-time combustion. At this time, when the second stage combustion flame is detected, the fuels of the first and second stages are increased in accordance with the specified flow rate increase rate to increase the load. At this time, at the start of the second stage combustion, the total fuel amount of the first and second stages is controlled to be equal to that before the second stage combustion, and the load is controlled so as not to cause a sudden load increase due to the second stage combustion.

Therefore, it is necessary to apply the operating method of the present invention when the second-stage flame does not occur despite the injection of the fuel for secondary combustion, or when the second-stage flame once generated disappears. .

Next, one example of the mode for carrying out the method of the present invention will be described. When the second-stage flame cannot be detected, that is, when there is no ignition, the second-stage fuel supply is promptly stopped and the first-stage fuel is increased. Make sure there is no sudden load change. On the other hand, when the second stage combustion misfires during load operation, the second stage fuel is increased by slightly increasing the amount of the second stage fuel, and at this time, the first stage fuel is commensurate with the increase in the second stage fuel amount. By reducing the amount and performing the second stage ignition, it is possible to suppress the decrease in turbine efficiency and continue the load operation.
In this way, damage to the gas turbine is suppressed, and sudden load fluctuations and turbine efficiency reduction do not occur.

〔Example〕

FIG. 1 is a cross-sectional view showing an example of a gas turbine two-stage combustor configured to carry out an operating method according to the present invention.

The gas turbine is composed of the main components of the compressor 1, the turbine 2, and the combustor 3. The air 1a compressed by the compressor 1 passes through the vehicle interior 4 and is guided to the combustor 3. The combustor 3 is constituted by outer cylinders 5a and 5b, a head liner 6a, a rear liner 6b, an inner cylinder 7 and a second-stage fuel-air premixing section 8. The head combustion chamber 9 is an annular portion formed by the head liner 6a and the inner cylinder 7, and the rear combustion chamber 10 is a space for burning the fuel from the premixing unit 8. A primary fuel (F ₁ ) 11 is supplied to the side closed end of the head combustion chamber 9 1
The next fuel nozzle 12 is attached to the cover 13.

The liner 6a is provided with a plurality of rows and a plurality of rows of air holes 1b for the first-stage combustion, and is further provided with air holes for cooling the wall surface. The cooling holes are also opened in the inner cylinder 7.

A secondary air supply hole 18 is provided in a continuous portion 17 of the head combustion chamber 9 and the rear combustion chamber 10, and a secondary air supply hole 18 is provided in the air passage portion 19.
Secondary fuel is supplied from the secondary fuel nozzle 20, and this air passage portion 21 serves as a premixing portion 8 for secondary air and fuel. The premixed gas 22 is supplied to the rear combustion chamber 10, and the primary flame 23 from the head combustion chamber is used as an ignition source to transfer the flame to form a secondary flame 24. Although not shown, the primary fuel is ignited by a spark plug, and a flame detector detects the flame. On the other hand, the detection of the secondary combustion flame 24 includes a flame detector 25 to detect the presence or absence of the second stage flame (the flame of the secondary combustion by the fuel for the secondary combustion).

The second stage flame is detected by the detector 25, and the detection signal output 32 enters the controller 33 as a control signal, and the controller 33 regulates the primary combustion fuel (F ₁ ) 11. 15 and a control signal 31 for adjusting the secondary combustion fuel (F ₂ ) 28, and a control signal for the ring 27, which will be described later with reference to FIG.

FIG. 2 shows a partial detailed structure of the combustor 3. A ring 27 is attached which covers the inlet of the secondary air passage 26 and moves back and forth (left and right in the figure) to change the area of the air inlet to change the secondary air flow rate. A lever mechanism is used for this ring 27. The air flow rate is adjusted by moving it from the outside. The secondary fuel 28 is introduced into the fuel manifold chamber 30 which penetrates the secondary flange 29,
Then, it is guided to the secondary fuel nozzle 20 located in the air passage 21. The secondary fuel and air are always controlled at a certain ratio, and when the amount of the secondary fuel 28 increases, the ring 27 opens to increase the air flow rate and the combustion is performed at a constant ratio even if the fuel and the air load change. In addition, the same effect can be obtained by increasing or decreasing the air flow rate that is controlled at a constant ratio with the second-stage fuel by adopting a system in which the second-stage air flow rate can be controlled by adjusting the overall combustion air pressure. It has been obtained and is aimed at reducing NOx.

The operation control from the start of the gas turbine to the rated load is performed by increasing the air flow rate along with the increase in the rotation speed from ignition to 100% rotation speed. Although the fuel is further increased to increase the load, only the primary fuel is used from ignition to 25% load, and the secondary fuel is injected at around 25%. At 25% or more, the secondary fuel is increased to further increase the load. When the secondary fuel is input, the primary fuel is reduced, and the secondary fuel is increased in proportion to the reduced amount. Even if the secondary fuel is injected and ignited, the load does not exceed 25% and the load does not suddenly increase. Fig. 3 shows the operation method after the secondary fuel is added. Drop the primary fuel (F ₁ ) at a certain load point,
The injection of secondary fuel (F ₂ ) commensurate with this is started. When the specified amount the flame of F ₂ be charged an F ₂ amount is not detected, increases rapidly F ₁ fuel in comparison with the prior art example shown by the broken line (the F ₁ fuel before F ₂ fuel input (Returning to the amount), the supply of F ₂ fuel is stopped. As a result, the load fluctuation of the gas turbine can be suppressed, and the emission of the unburned F ₂ can be suppressed in a short time, so that the turbine efficiency can be suppressed as short as possible. When restarting from this state, combustion of F ₂ can be achieved by further narrowing the stroke of the ring 27 or slightly increasing the prescribed amount of F ₂ injection. On the other hand, FIG. 4 shows the operation when the combustion of F ₂ is normally performed.
When the amount of F ₁ fuel is decreased and the amount of F ₂ fuel is increased to supply a specified amount, when the detection of F ₂ flame is confirmed, the amount of combustion of F ₁ and F ₂ is promptly increased along with the specified pattern. Try to increase the load. On the other hand, when the load increases or F ₂
The operation when the combustion is misfired is shown in FIG. Since F ₂ misfire can be determined by the signal of the fire detector, in this example, F ₂ fuel is slightly increased and F ₁ fuel corresponding to this is decreased compared to the conventional method shown by the dotted line. Alternatively, by moving the A ₂ air flow rate adjusting ring so that the A ₂ area becomes narrower, F ₂ comes into the combustible range and F ₂ flame comes to be detected. By operating in this way, it is possible to realize a driving operation in which the load is not reduced and the efficiency is not reduced.

〔The invention's effect〕

As described above, according to the operating method of the present invention, it is possible to determine ignition of secondary combustion, non-ignition, and misfire during load operation based on the detection signal of the second stage flame due to combustion of secondary fuel. Therefore, the first order (F
₁ ) By operating fuel and secondary (F ₂ ) fuel in combination and controlling A ₂ air flow rate in combination, the F ₂ unburned range can be suppressed as much as possible, and rapid changes in gas turbine load can be suppressed. In addition to the excellent practical effect of being able to prevent the deterioration of turbine efficiency, it also contributes to the improvement of the durability of the constituent members by preventing the thermal shock due to the sudden change of the combustion gas temperature.

[Brief description of drawings]

FIG. 1 shows a configuration 2 for implementing the operating method of the present invention.
FIG. 2 is a sectional view of the staged combustor, and FIG. 3 to 5 are charts for explaining the embodiments of the present invention. 3 ... Combustor, 23 ... Primary combustion flame, 24 ... Secondary combustion flame, 25 ... Second stage flame detector due to combustion of secondary fuel, 32 ... Flame detector output signal, 33 ... … Controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Inose 3-1-1, Saiwaicho, Hitachi, Ibaraki Hitachi Ltd. Hitachi factory (56) References JP-A-50-83612 (JP, A) JP 62-77520 (JP, A) JP 59-18237 (JP, A)

Claims (3)

[Claims] 1. A primary combustion fuel nozzle and a head combustion chamber are provided on the upstream side of the combustion chamber, and a secondary combustion fuel nozzle and a rear combustion chamber are provided on the downstream side thereof, and combustion air is provided. Alternatively, in a method of operating a two-stage combustor for a gas turbine provided with a secondary combustion air flow rate adjusting means, a means for detecting a second-stage flame of secondary combustion performed in the rear combustion chamber is provided. After fuel injection, at least one of control of the primary combustion fuel flow rate and secondary combustion fuel flow rate and / or combustion air flow rate control is performed based on the output signal of the flame detection means. The control of the secondary combustion fuel flow rate and the secondary combustion fuel flow rate is performed by stopping the supply of the secondary combustion fuel and stopping the supply of the secondary combustion fuel when the second-stage flame is not detected after the secondary combustion fuel is input. Increased supply, followed by secondary combustion 2 for baking
A method for operating a two-stage combustor of a gas turbine, characterized in that the second stage fuel flow rate is reduced and the secondary combustion fuel is reintroduced. 2. A primary combustion fuel nozzle and a head combustion chamber are provided upstream of the combustion chamber, and a secondary combustion fuel nozzle and a rear combustion chamber are provided downstream thereof, and combustion air is provided. Alternatively, in a method of operating a two-stage combustor for a gas turbine provided with a secondary combustion air flow rate adjusting means, a means for detecting a second-stage flame of secondary combustion performed in the rear combustion chamber is provided. After fuel injection, at least one of the control of the primary combustion fuel flow rate and the secondary combustion fuel flow rate and the control of the combustion air flow rate is performed based on the output signal of the flame detection means, and the two-stage control is performed. When the detection of the second stage flame is interrupted after the eye flame is once detected, the supply of the fuel for secondary combustion is increased, and correspondingly, the supply of fuel for primary combustion is decreased, and 2 What promotes the transfer to the step flame The method for operating a two-stage combustor of a gas turbine, comprising: 3. A primary combustion fuel nozzle and a head combustion chamber are provided upstream of the combustion chamber, and a secondary combustion fuel nozzle and a rear combustion chamber are provided downstream thereof, and combustion air is provided. Alternatively, in a method of operating a two-stage combustor for a gas turbine provided with a secondary combustion air flow rate adjusting means, a means for detecting a second-stage flame of secondary combustion performed in the rear combustion chamber is provided. After fuel injection, at least one of the control of the primary combustion fuel flow rate and the secondary combustion fuel flow rate and the control of the combustion air flow rate is performed based on the output signal of the flame detection means, and the two-stage control is performed. When the detection of the second stage flame is interrupted after the second stage flame is once detected, the flow rate of the secondary combustion air is reduced to promote the transfer to the second stage flame. Operation method of two-stage combustor of gas turbine.