JPH07119492A - Combustion device for gas turbine and control method therefor - Google Patents

Abstract

PURPOSE:To perform rapid detection of a backfire and a misfire state by a method wherein a temperature sensor is arranged to a flame stabilizer and a correction control device to effect correction control of a feed fuel flow rate and a feed air flow rate to a premixer by means of a temperature change signal from a temperature sensor is arranged to a control device. CONSTITUTION:A flame stabilizer 12 is arranged to the outlet part of a premixer 10 and temperature sensors 24 and 25 are arranged to the flame stabilizer. Through the temperature sensors 24 and 25, a signal for a deviation from a plan value is transmitted from a heating value measuring device 16, an exhaust gas temperature measuring device 17, and a flame stabilizer temperature measuring device 18 to an air flow rate adjustment corrector 19 and a fuel distribution corrector 20 to distribute and correct fuel 7a for diffusion combustion and fuel 8a for premixture combustion. The signal is added to a signal from an air flow rate regulation setter 21 by an adder 22 and air 9 for premixture combustion is regulated by an air flow rate regulator 11 and brought into a proper combustion state. Thus, even when a backfire occurs, there is no fear of the premixer 10 being brought into a seizure state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in a gas turbine combustion apparatus and a control method thereof, and more particularly to a gas turbine combustion apparatus having a combustor in which premixed combustion is performed and a control method thereof. .

[0002]

2. Description of the Related Art NOx (nitrogen oxide) generated when natural gas or kerosene or light oil is burned is thermal NOx generated by oxidizing nitrogen in the air. The generation of thermal NOx is naturally highly temperature dependent,
Generally, in a gas turbine that uses a fuel having a low nitrogen content, reduction of flame temperature is a basic idea of the low NOx combustion method.

In particular, a combustion device used in a gas turbine is different from a combustion device used in a boiler or the like in that the fuel flow rate changes depending on the load of the gas turbine, but the air flow rate is almost constant, and the fuel flow rate is almost constant. The fuel-air ratio, which is the mass flow rate ratio between air and air, changes significantly between partial load and 100% rated load.

Even in the vicinity of the rated load at which the fuel flow rate becomes maximum, a large amount of air, which is almost twice the theoretical air amount required for complete combustion of fuel, is supplied. Therefore, lean combustion in which a flame is formed with a large excess of air can be applied, and this is the mainstream technology of the NOx reduction method adopted in the current combustor.

The gas fuel combustion method is roughly classified into a diffusion combustion method in which fuel and air are burned while being mixed, and a premixed combustion method in which fuel and air are premixed and ejected from a nozzle.

Diffusion combustion is excellent in flame stability and can form a flame in a wide fuel-air ratio range, but since fuel and air are burned while being mixed, the fuel-air ratio changes spatially in the flame. Even if a lean burn is tried, a part of the fuel burns in an excessive fuel state. Therefore, the flame temperature locally rises, and a large amount of NOx is easily generated.

On the other hand, in the premixed combustion, the fuel and the air are premixed before being introduced into the combustion chamber, so that the fuel-air ratio in the flame can be made more uniform than the diffusion combustion, and the mixing is not uniform. Since there is no local formation of a high temperature part, the effect of reducing NOx is great.

However, this method has a drawback in that the conditions of the fuel-air ratio and the premixer outlet velocity for stably forming a flame are narrower than those of diffusion combustion. In particular, in the operation from the start of the gas turbine to 100% load, or in the load shedding operation in an emergency, the fuel flow rate changes widely, so it is difficult to operate the gas turbine only by premixed combustion.

For this reason, generally, a so-called two-stage combustion method is used in which diffusion combustion is used from the start up to a certain partial load, and premixed combustion is started above a certain load (Japanese Patent Laid-Open No. 61-22106). Japanese Patent Laid-Open No. 61-22127).

As described above, in the gas turbine, the premixed combustion is adopted as the main combustion. In this premixed combustion, in order to form the premixed flame, the jet speed of the air-fuel mixture and the combustion rate are set. It is necessary to set the sky ratio above a certain value. In other words, when the jet speed increases, the flame blows out,
When the temperature becomes lower, a flame enters the mixture jet nozzle, which is so-called flashback.

In order to operate the gas turbine combustor stably over a wide load range, it is necessary to properly set the combustion conditions. For this purpose, it is necessary to monitor or detect blowout or flashback and take prompt action. There is.

As a flame monitoring method which has been generally adopted in the past, a TV is provided through a flame detecting device or a fiberscope for detecting light from the flame by using a photodiode.
There are things such as monitoring the flame by visualizing it on a camera.

Incidentally, as for those related to this, Japanese Patent Laid-Open Nos. 63-150634 and 63-263.
No. 427, etc. are mentioned.

[0014]

It is true that such a flame detecting device utilizing light has good responsiveness and is effective for confirming misfire and ignition, however, flame enters the jet nozzle of the mixer. When it is attempted to detect a state, that is, a flashback phenomenon, the detection cannot be performed by the one in which the optical sensor is arranged outside the flame, and the optical sensor is arranged in the mixer.

In this case, if only the light entering the mixer is to be detected, it is necessary to take measures to prevent stray light from coming into the combustion chamber, and the structure of the detector or the structure of the mixer must be determined from the relationship with the mixed jet gas. It gets complicated.

Further, in the detection device utilizing light, even if the flashback can be detected, the light is detected after passing through the device for preventing the stray light, that is, the device for blocking the stray light. It will be detected only after the flashback occurs, that is, it will be dealt with after a predetermined time after the flashback occurs, and in this case, there is a possibility that the jet part of the premixer will be burned out by the flashback. there were.

The present invention has been made in view of the above circumstances, and an object thereof is to quickly detect a flashback and a misfire state, that is, to take prompt action, and even if a flashback occurs, the premixer may burn out. Not in providing this kind of gas turbine combustion device.

[0018]

That is, according to the present invention, a temperature sensor is provided in a flame stabilizer arranged on the air-fuel mixture discharge side of a premixer, and the flow rate of fuel and combustion air supplied to the premixer is increased. The control device that controls the fuel flow rate according to the load is provided with a correction control device that corrects and controls the fuel flow rate and the air supply flow rate to the premixer based on the temperature change signal from the temperature sensor. It was something that was achieved.

[0019]

In the gas turbine combustion device thus formed, a temperature sensor is arranged in the most temperature-sensitive flame stabilizer, and a correction controller is used to detect the degree or change of this temperature. Since the flow rate of fuel supplied to the mixer and the flow rate of air supplied to the mixer are corrected and controlled, flashback and misfire conditions can be detected quickly, and the supply flow rate associated therewith can be controlled. ,
Burnout is prevented.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. FIG. 2 shows a diagram of the combustion apparatus of the gas turbine and its surroundings.

The gas turbine mainly comprises an air compressor 1 for supplying combustion and cooling air, a combustion device 3 for generating high temperature and high pressure gas, and a turbine 2 driven by the gas generated by a combustor 3a of the combustion device. It is composed of

The air 1a from the compressor 1 is guided to the combustor 3a, and becomes the combustion gas 4 in the combustor 3 and flows into the turbine 2. In this case, the combustor 3a includes the diffusion combustion unit 5
And a premix combustion section 6.

In the diffusion combustion section 5, the fuel 7a ejected from the fuel nozzle 7 is combusted by the air flowing in from the combustion air holes provided in the combustion cylinder wall. On the other hand, in the premix combustion section, the fuel 8a ejected from the fuel nozzle 8 is supplied to the premixer 10
After being mixed with air 9 therein, it is put into a combustion chamber and burned.

In this embodiment, an air flow controller 11 for adjusting the area of the inflow hole is installed in the air inflow hole of the premixer,
This regulates the flow rate of air flowing into the premixer.
A flame stabilizer 12 is installed at the outlet of the premixer 10, and a premix flame is formed downstream of the flame stabilizer.

The total flow rate of fuel injected into the combustor 3a is set by the load command device 13 of the gas turbine, and is set at the combustor inlet via the fuel flow rate control valves 14 and 15 for diffusion combustion and premixed combustion. Will be divided.

Only the diffusion flame is formed at the time of starting the gas turbine and at the time of low load operation, the fuel 8a for premix combustion is injected at a certain load or more, and the high temperature combustion gas from the diffusion combustion section 5 is used for premix combustion. The fuel 8a is ignited. Diffusion combustion and premixed combustion are used together when the gas turbine is operated above the load at which the premixed flame is formed.

FIG. 1 shows the combustion control device and the premixer 10 at this time. A flame stabilizer 12 is provided at the outlet of the premixer 10, and a flame is formed in the vortex portion 23 generated downstream of the flame stabilizer 12. A thermocouple is installed as a temperature sensor 24 in the flame stabilizer 12.

The operating conditions of the combustor are set by the combustion control device. The combustion control device has a load command, a fuel heating value,
The atmospheric humidity, the flame stabilizer temperature, and the gas turbine exhaust gas temperature are transmitted, and based on these signals, the flow rates of the diffusion combustion fuel 7a and the premixed combustion fuel 8a, the command to the air flow rate controller 11, etc. are set. It

The calorific value of the fuel is determined by the diffusion combustion fuel control valve 1
4. Sampling from upstream of the premixed combustion fuel control valve 15, and the gas turbine exhaust gas temperature and flame stabilizer temperature are respectively measured by a calorific value measuring device 16, via a temperature sensor.
A signal corresponding to the deviation from the planned value is sent from the exhaust gas temperature measuring device 17 and the flame stabilizer temperature measuring device 18 to the air flow rate adjustment compensator 1.
9 and the fuel 7a for diffusion combustion and the fuel 8a for premixed combustion are sent to the fuel distribution corrector 20 which corrects distribution.

The atmospheric humidity is sampled from the inlet of the compressor 1, and the atmospheric humidity measuring device 21 sends a signal corresponding to this fluctuation to the air flow rate adjusting compensator 19.

These signals are added by the signal output from the air flow rate adjustment setter 21 from the fuel control command 20 and the adder 22 to adjust the premixed combustion air 9 by the air flow rate adjuster 11. Further, the diffusion combustion fuel 7a and the premixed combustion fuel 8a are adjusted so as to be in an appropriate combustion state by receiving a signal from the fuel distribution corrector 20.

When the premixed combustion fuel is ignited by the combustion gas from the diffusion combustion section 5, the diffusion combustion fuel 7a is reduced, and the premixed fuel 8a is injected by the reduced amount. The fuel flow rate and air flow rate are adjusted by the atmospheric humidity and the signal from the fuel calorific value measuring / measuring device 16 so as to prevent flashback and misfire of the premixed flame.

When the premixed flame is formed, the temperature of the flame stabilizer 12 rises. Therefore, when the flame stabilizer temperature does not rise above a certain temperature within a few seconds after the premixed fuel is supplied, the supply of the premixed fuel 8a is stopped, and the combustion condition before the start of premixed combustion is restored to the operating condition of the combustor. Before the ignition of the premixed flame again, the fuel flow rate and the air flow rate are reset.

When the temperature of the flame stabilizer 12 exceeds a certain value,
Since there is a high possibility that the premixed flame will enter the premixer and burn out the premixer and the flame stabilizer, the fuel flow rate and the air flow rate are adjusted so that the flame stabilizer temperature becomes low.

3 to 7 show the relationship between the flame holding state and the temperature change of the temperature sensor 24, respectively. In this case, the value of the temperature change in each flame holding state often differs depending on the combustor, and it is of course necessary to confirm it in advance.

FIG. 3 shows a temperature change when a flashback occurs. When the flame held in the flame stabilizer 12 flashes back to the mixer side, the measured temperature rises rapidly. start. In this case, shut off the fuel 8a (see FIG. 2),
Alternatively, the fuel 8a is decreased and the air flow controller 11 is opened to increase the air 9.

Further, a temperature sensor 25 is installed in the downstream portion (flame holding portion) of the flame stabilizer (see FIG. 1).
If 25 is monitored at the same time, it is determined that the flame stabilizer has ignited the flame with the temperature change shown in FIG.

In FIG. 5, it is determined that a misfire has occurred when the temperature falls below a certain temperature, in which case the fuel 8a for premixed combustion is shut off and this fuel 8a is sent to the fuel 7a for diffusion combustion. Above a certain temperature, since the flame holding state is still maintained, the fuel 8a is increased or the air flow rate controller 11 is opened and the air 9 is decreased to set the proper combustion state.

FIG. 6 shows the case of flashback when two temperature sensors are provided, and the same operation method as that of FIG. 3 described above is adopted.

In the case of the temperature change shown in FIG. 7, flame holding-
It is determined that the misfire is occurring intermittently, and the fuel 8a is increased or the air flow rate controller 11 is opened and the air 9 is decreased to set the proper combustion state.

FIG. 8 shows the installed state of the temperature sensor installed in the flame stabilizer. Since the temperature sensor is exposed to a high temperature atmosphere when flashback occurs, there is a possibility of breaking or burning if flashback occurs repeatedly.
Further, the lead wire of the temperature sensor may be broken when the premixer 10 is incorporated in the combustor. Therefore,
It has a replaceable structure and is embedded in the flame stabilizer.

In the case of the flame stabilizer 26 shown in FIG. 8, a temperature sensor (for example, a thermocouple) 27 installed upstream of the flame stabilizer is inserted and installed in the conduit 28. The temperature sensor 29 installed in the flame holding unit is fixed by the conduit 30.

In the case of the flame stabilizer 31 shown in FIG. 9, the temperature sensor 32 installed in the flame stabilizer or upstream of the flame stabilizer has a hole in the mounting plate 33 and the flame stabilizer 31 to the extent that the temperature sensor 32 passes. Give and install. The temperature sensor 34 installed upstream of the flame stabilizer is installed by forming a hole 35 in the flame stabilizer.

A plurality of these temperature sensors are installed in the circumferential direction of the flame stabilizer, and are gathered in one place. If even one of the measured temperatures of these temperature sensors detects the temperature change corresponding to the above-described FIGS. 3 to 7, the combustion control corresponding to the detected temperature change is executed.

As described above, the combustion state can be accurately determined from the change in temperature measured by the temperature sensor, and an appropriate combustion state can be set.

[0046]

As described above, according to the present invention, the temperature sensor is arranged in the flame stabilizer, and the flow rate of fuel supplied to the premixer and the flow rate of supplied air to the premixer are corrected and controlled by grasping the degree or change of this temperature. Therefore, a backfire or misfire state is quickly detected, and the supply flow rate is controlled accordingly. Therefore, even if a backfire occurs, the premixer will not burn out. Can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a gas turbine combustion apparatus of the present invention.

FIG. 2 is a diagram showing the periphery of a gas turbine combustion device of the present invention.

FIG. 3 is a temperature characteristic diagram of the gas turbine combustion apparatus of the present invention during flashback.

FIG. 4 is a temperature characteristic diagram at the time of ignition of the gas turbine combustion device of the present invention.

FIG. 5 is a temperature characteristic diagram at the time of misfire of the gas turbine combustion device of the present invention.

FIG. 6 is a temperature characteristic diagram of the gas turbine combustion device of the present invention during flashback.

FIG. 7 is a temperature characteristic diagram during ignition / misfire of the gas turbine combustion device of the present invention.

FIG. 8 is a vertical cross-sectional side view of a flame stabilizer showing an embodiment of the gas turbine combustion apparatus of the present invention.

FIG. 9 is a vertical sectional side view of a flame stabilizer showing another embodiment of the gas turbine combustion apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Turbine, 3 ... Combustor, 4 ... Combustion gas, 5 ... 1st stage combustion part, 6 ... 2nd stage combustion part, 7 ... 1st stage fuel nozzle, 7a ... 1st stage fuel, 8 ... 2nd stage fuel nozzle, 8a ... 2nd stage fuel, 9 ... Air, 10 ... Premixer, 1
1 ... Air flow controller, 12, 26, 31 ... Flame stabilizer, 14
... fuel control valve for diffusion combustion, 15 ... fuel control valve for premixed combustion, 23 ... vortex of flame stabilizer wake, 24, 25, 27, 29,
32, 34 ... Temperature sensor, 28, 30 ... Conduit, 33 ...
Flame stabilizer mounting plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naohiko Iwata 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory

Claims (8)

[Claims] 1. A premixer for mixing fuel and combustion air, a flame stabilizer provided in the vicinity of an air-fuel mixture outlet of the premixer, and an amount of fuel and combustion air supplied to the premixer. In a combustion apparatus for a gas turbine, which comprises a control device for controlling the premixer according to a load, a temperature sensor is provided in the flame stabilizer, and the control device includes a premixer with a temperature change signal from the temperature sensor. A combustion apparatus for a gas turbine, comprising a correction control device for correcting and controlling a flow rate of fuel supplied to and a flow rate of air supplied to the gas turbine. 2. A premixer for mixing fuel and combustion air, a flame stabilizer provided near the mixture outlet of the premixer, and amounts of fuel and combustion air supplied to the premixer. In a combustion device of a gas turbine comprising a control device for controlling according to the load, on the combustion chamber side and the premixer side of the flame stabilizer, each with a temperature sensor, the control device, A combustion apparatus for a gas turbine, which is provided with a correction control device that corrects and controls a flow rate of fuel supplied to a premixer and a flow rate of supplied air by a temperature difference change signal from both temperature sensors. 3. A premixer for mixing fuel and combustion air, a flame stabilizer provided near the mixture outlet of the premixer, and amounts of fuel and combustion air supplied to the premixer. In a combustion device of a gas turbine comprising a control device for controlling according to the load, on the combustion chamber side and the premixer side of the flame stabilizer, each with a temperature sensor, the control device, A combustion apparatus for a gas turbine, comprising a correction control device for reducing the flow rate of fuel supplied to the premixer and the flow rate of supply air when the temperature difference between both temperature sensors is equal to or less than a predetermined value. 4. A premixer for mixing fuel and combustion air, a flame stabilizer provided near the mixture outlet of the premixer, and flow rates of fuel and combustion air supplied to the premixer. In a gas turbine combustion device comprising a control device for controlling according to the load, the flame stabilizer is provided with a plurality of temperature sensors at a predetermined interval in the flow direction of the air-fuel mixture, The control device is provided with a correction control device for reducing the flow rate of fuel supplied to the premixer and the flow rate of supply air when the temperature difference between the plurality of temperature sensors changes to a predetermined value or less. Turbine combustion device. 5. A premixer for mixing fuel and combustion air, a flame stabilizer provided near the mixture outlet of the premixer, and a flow rate of fuel and combustion air supplied to the premixer. In a combustion device of a gas turbine comprising a control device for controlling according to the load, on the combustion chamber side and the premixer side of the flame stabilizer, each with a temperature sensor, the control device, When the temperature difference between both temperature sensors is less than or equal to a predetermined value, the fuel flow rate and air supply to the premixer are controlled so that the temperature detected by the temperature sensor arranged on the premixer side falls within a predetermined temperature range. A combustion device for a gas turbine, which is provided with a correction control device for reducing a flow rate. 6. The gas turbine combustion device according to claim 1, wherein a thermocouple is used as the temperature sensor, and the thermocouple is embedded inside the flame stabilizer. 7. A premixer for mixing fuel and combustion air, a flame stabilizer provided near the mixture outlet of the premixer, and a flow rate of fuel and combustion air supplied to the premixer. In the method for controlling a gas turbine combustion apparatus including a control device that controls according to a combustor load, the flame stabilizer is provided with a temperature sensor, and the control device detects the temperature sensor. When the temperature is below a predetermined value, a correction control device is provided to reduce the flow rate of fuel and air supplied to the premixer, and when the temperature indicated by the temperature sensor is lower than the set temperature range, the fuel for premix combustion is Shut off and reset the premixed combustion fuel or air flow rate, and then feed the premixed fuel into the combustor.When the temperature indicated by the temperature sensor is higher than the set temperature range, premixed combustion is performed so that it falls within the set temperature range. Empty space A method of controlling a combustion apparatus of a gas turbine, which comprises adjusting a flow rate of air or fuel. 8. A premixer for mixing fuel and combustion air, a flame stabilizer provided near the mixture outlet of the premixer, and amounts of fuel and combustion air supplied to the premixer. To
In a method for controlling a gas turbine combustion device, which comprises a control device for controlling a combustor load, a fuel calorific value, an atmospheric temperature, an atmospheric humidity, and a guide vane angle for adjusting a compressor inlet air flow rate, the flame stabilizer is provided. , A plurality of temperature sensors are arranged at a predetermined interval in the flow direction of the air-fuel mixture, and when the temperature difference detected by the plurality of temperature sensors is below a predetermined value, the premixer A correction control device that reduces the flow rate of fuel and air supplied to the air conditioner is provided, and the fuel heat value, atmospheric temperature, atmospheric humidity, and guide vane angle for adjusting the compressor inlet air flow rate are detected, and the supply air is detected from these detection signals. First, the flow rate and the supplied fuel flow rate are set, and thereafter, the air flow rate or the fuel flow rate of the premix combustor is adjusted by the correction control device so that the temperature indicated by the temperature sensor falls within the set temperature range. The method of the combustion apparatus of a gas turbine, characterized in that to adjust the.