JP3425191B2 - Gas turbine combustor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims at reducing NOx by a two-stage combustion system of combustion using pilot fuel and combustion using main fuel, and at the same time, reverses to premixed gas. Monitor the fire,
The present invention relates to a gas turbine combustor that stabilizes combustion gas even when flashback occurs. 2. Description of the Related Art Generally, N gas in a gas turbine combustor is used.
The main cause of the generation of Ox is that a combustion region in which the equivalent ratio of fuel and air is close to 1 is generated in the combustion gas, and the combustion gas locally rises in temperature in this combustion region. As a means for suppressing NOx generated by such factors, there is a lean premix combustion system. A gas turbine combustor to which the lean premixed combustion system is applied is disclosed, for example, in Japanese Patent Application Laid-Open No. Sho 61-11081.
No. 7 is disclosed. When the combustion air 1 and the main fuel 2a are mixed in the premixing duct 3 as shown in FIG. 8, the gas turbine combustor turns into a premixed gas 4, and the premixed gas 4 is combusted in a combustor liner 5. Room 6
Burning in. However, since the premixed gas 4 is a flammable gas, it may burn in the premixed duct 3 due to flashback or the like. As a gas turbine combustor for avoiding this, there is one as shown in FIG. That is, in this gas turbine combustor, the premixing duct 3 is provided in a combustor liner 5, and the combustor liner 5 is connected to a pilot fuel nozzle 7 attached to a central portion of a head plate 8. . The combustion air 1 is supplied from a compressor (not shown), flows through the outer peripheral wall of the combustor liner 5, passes mainly through the swirl vanes and the premixing duct 3 attached to the pilot fuel nozzle 7, and passes through the combustor liner 5. Into the combustion chamber 6 in the interior. The flow rate of the fuel 2 is adjusted by a fuel flow control valve 9 via a fuel cutoff valve 9a, and the main fuel 2a and the pilot fuel 2b are supplied to a main fuel distribution valve 10 respectively.
And a pilot fuel distribution valve 11. The main fuel 2a is injected into the premixing duct 3 from a main fuel nozzle 12 attached to the head plate 8, becomes a premixed gas in the combustion air 1 and the premixing duct 3, and becomes a combustion chamber 6 in the combustor liner 5. On the other hand, the pilot fuel 2 b is supplied to the combustor liner 5 by the pilot fuel nozzle 7.
It is injected inside and burns. A flashback detection sensor 13 is arranged in the premixing duct 3. A detection signal from the flashback detection sensor 13 is received by a flashback detector 14, and when a flashback is detected, the fuel cutoff valve 9 is provided.
A is closed to stop the gas turbine, and the alarm device 15 gives an alarm to that effect. The state of the flashback detector 14 is monitored by the monitor 16. Therefore, FIG. 10 shows the relationship between each fuel flow rate when a flashback is detected. When flashback is detected at time A, the main fuel 2a and the pilot fuel 2b are shut off by the fuel shutoff valve 9a. Therefore, the fuel flow rates Qa and Qb simultaneously become zero. Such a flashback monitor for a combustor is disclosed in Japanese Utility Model Laid-Open No. 61-39253 and Japanese Utility Model Laid-Open No. 61-39.
No. 254, Japanese Unexamined Patent Publication No. 3-102118, and the like. The invention disclosed in Japanese Utility Model Application Laid-Open No. 61-39253 and Japanese Utility Model Application Laid-Open No. 61-39254 relates to attaching a thermocouple to monitor the occurrence of flashback or combustion vibration, and the means for attaching the thermocouple. . The invention disclosed in Japanese Patent Application Laid-Open No. 3-102118 confirms the ignition of a combustion flame, stops the gas turbine when an abnormal value of the combustion flame is detected, and adjusts the temperature level of the combustion flame and the exhaust gas concentration. The first and second combustion rates are controlled so as to be kept constant. However, in the conventional gas turbine combustor as described above, when a flashback is detected in the premixing duct, the gas turbine is emergency stopped and the like is dealt with. Was. Therefore, it took a long time to restart and return to the original normal operation state. Further, when the gas turbine is restarted and returned by the same operation method, there is a possibility that a flashback occurs again. The present invention has been made in view of the above-described circumstances, and a flashback occurs in a premixed duct, and even in the case of abnormal combustion, the abnormal combustion flame is extinguished without changing the load on the gas turbine. It is an object of the present invention to provide a gas turbine combustor that returns to normal operation so as not to reproduce a state in which a flashback has occurred when it is confirmed. [0014] In order to solve the above-mentioned problems, a first aspect of the present invention is to inject a first-stage fuel pilot fuel into a combustion chamber, diffuse and mix it with air to perform diffusion combustion. A first-stage fuel nozzle, a pre-mix duct for pre-mixing the second-stage fuel main fuel and air and supplying the mixture to the combustion chamber, and a pre-mix gas flow that is disposed at an inlet of the pre-mix duct and flows into the combustion chamber. In a gas turbine combustor having a premixed fuel injection nozzle to be injected, a first-stage fuel pilot fuel supply system for supplying a first-stage fuel pilot fuel to the first-stage fuel nozzle; A second-stage fuel main fuel supply system for supplying a two-stage fuel main fuel, a sensor for detecting a backflow flame flowing backward from the combustion chamber into the premixing duct, and a detection signal from the sensor. A flashback analysis device that stores the presence or absence of a flashback flame based on the second-stage fuel main fuel supply system,
A branch fuel supply system for supplying a second-stage fuel main fuel to the first-stage fuel nozzle, and when a flame flows back into the premixing duct from the combustion chamber, the flame based on an output signal of the flashback analysis device. The fuel valve for the second stage main fuel provided in the second stage main fuel supply system is closed , and
A switching mechanism for opening a second-stage fuel main fuel branch fuel valve provided in the fuel supply system. [0015] In the present invention having the above structure [action], when the backflow flame generated in the premixing duct, a second stage fuel main fuel for a fuel valve provided in the second stage fuel main fuel supply system
The second-stage fuel main that is closed and installed in the branch fuel supply system
Since a switching mechanism that opens the fuel valve for fuel branching is provided,
Extinguish flashback by closing fuel valve for second fuel main fuel
The second stage fuel valve for main fuel branch fuel
Without shutting down the gas turbine by opening
The output can be maintained high as it is. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing one embodiment of a gas turbine combustor according to the present invention. Parts that are the same as or correspond to those in the conventional configuration will be described using the same reference numerals as in FIG. As shown in FIG. 1, the premixing duct 3 is provided in a combustor liner 5, and this combustor liner 5 is disposed at the inlet of the premixing duct 3 and attached to the center of the head plate 8. And a pilot fuel nozzle 7 as a first-stage fuel nozzle. The combustion air 1 is supplied from a compressor (not shown), flows through the outer peripheral wall of the combustor liner 5, passes mainly through the swirl vanes and the premixing duct 3 attached to the pilot fuel nozzle 7, and passes through the combustor liner. Flow into 5. The flow rate of the fuel 2 is adjusted by a fuel flow control valve 9 via a fuel cutoff valve 9a, and the second-stage fuel main fuel 2a and the first-stage fuel pilot fuel 2b are respectively supplied to a second-stage fuel main fuel distribution valve. 10 and a first stage fuel pilot fuel distribution valve 11. The second-stage fuel main fuel 2a is injected into the premixing duct 3 from a premixing fuel injection nozzle 12 attached to the head plate 8, and the premixed gas is mixed between the combustion air 1 and the premixing duct 3. And combusts in the combustion chamber 6 in the combustor liner 5. Also, the first stage fuel pilot fuel 2
The b is diffused and mixed with the combustion air 1 by the swirling vanes, injected into the combustor liner 5 by the pilot fuel nozzle 7, and diffused and burned in the combustion chamber 6. FIG. 2 shows an example of the relationship among the gas turbine load and the total fuel flow rate Q, the second-stage fuel main fuel flow rate Qa, and the first-stage fuel pilot fuel flow rate Qb. FIG. It shows the relationship among the container outlet equivalent ratio Ra, the premix duct equivalent ratio Rb, and the pilot fuel part equivalent ratio Rc. As shown in FIG. 1, in the premixing duct 3, a flashback detection sensor 13 comprising a temperature detection sensor or a flame detection sensor for detecting a counterflow flame from the combustion chamber 6 is disposed. When a backflow flame in the premix duct 3 is detected by the detector 14, the second-stage fuel main fuel flow rate Qa and the first-stage fuel pilot fuel flow rate Qb at that time are sent to the backfire analysis device 17 as storage means. Remember. The flashback analysis device 17 calculates the equivalent ratio in the premix duct 3 from the air flow amount stored in advance and stores it. The flashback detector 14 is a flashback detection sensor 1
The detection signal of No. 3 is obtained and sent to the flashback analysis device 17. When the flashback analysis device 17 analyzes that a flashback has occurred, the alarm device 15 gives an alarm to that effect. The state of the flashback analysis device 17 is constantly monitored by the monitoring monitor 16. On the other hand, the fuel is branched from the second-stage fuel main fuel supply system 19 having the second-stage fuel main fuel distribution valve 10 and is branched to the first-stage combustion nozzle 7.
A branch fuel supply system 20 for supplying c is provided.
Further, when a backflow flame is generated in the premixed duct 3, the fuel valve 2 for the second-stage main fuel of the second-stage main fuel supply system 19 is provided in the branched fuel supply system 20.
Second stage fuel main fuel branching fuel switched from 1
A valve 22 is provided. The fuel valve 22 for branching the second stage fuel main fuel includes a fuel switching valve (switching mechanism) 18 that operates in response to a signal from the flashback analysis device 17. The first-stage fuel nozzle 7 has a first-stage fuel pilot fuel supply system 2 having a first-stage fuel pilot fuel distribution valve 11 separately from the branch fuel supply system 20.
3 are provided. Next, the operation of this embodiment will be described. When the flashback flame from the combustion chamber 6 is detected by the flashback detection sensor 13 in the premixing duct 3, the detection signal is received by the flashback detector 14 and sent out to the flashback analysis device 17, where the flashback analysis is performed. If the device 17 analyzes that a flashback has occurred, the alarm device 15 gives an alarm to that effect. At the same time, a fuel switching valve (switching mechanism) 18
As a result, the second-stage fuel main fuel 2a is shut off, and the fuel is injected as a branched second-stage fuel main fuel 2c from a spare fuel hole provided in the first-stage fuel nozzle 7. Therefore, the total fuel flow Q does not change, and the load on the gas turbine does not change. Further, the flame in the premix duct 3 is extinguished due to the shutoff of the second-stage fuel main fuel 2a. When the extinguishing of the flame is detected by the flashback detection sensor 13 and the flashback detector 14, the branch second stage fuel main fuel 2c is shut off by the fuel switching valve (switching mechanism) 18, and at the same time the fuel is discharged. The fuel is injected into the premixing duct 3 as the second-stage fuel main fuel 2a, and returns to the original state. FIGS. 4 and 5 show this process in terms of the fuel flow rate and the equivalent ratio. In FIG. 4, when a flame is detected in the premixing duct 3 at time A, the first-stage main fuel flow Qa is cut off, and at the same time, the branched second-stage main fuel flow Qc is supplied. When the fire extinguishing is detected at time B, the branch second-stage fuel main fuel flow rate Qc is shut off, and at the same time, the first-stage fuel main fuel flow rate Qa is supplied. FIG. 5 shows the time elapsed when a flashback occurs, the combustor outlet equivalent ratio Ra, the premix duct equivalent ratio Rb, the first stage fuel pilot fuel equivalent ratio Rc, and the branch second stage fuel main fuel equivalent ratio Rd. The relationship is shown. FIGS. 6 and 7 show another embodiment of the gas turbine combustor according to the present invention. In this embodiment, the configuration of the gas turbine combustor is the same as that of the above embodiment. 6 and 7, when a flame is detected in the premixing duct 3 at time A, the first-stage fuel main fuel flow rate Qa is cut off and the branch second-stage fuel main fuel flow rate Qc is supplied. Is done. When fire extinguishing is detected at time B, the first-stage fuel main fuel flow rate Qa is set to a flow rate that is reduced by a preset equivalent ratio from the flashback equivalent ratio stored in the flashback analysis device 17. At this time, the reduced fuel is replenished at the branch second stage fuel main fuel flow rate Qc. During operation, if the first-stage fuel main fuel flow rate Qa becomes smaller than the flashback equivalent ratio stored in the flashback analysis device 17 after time C, the first-stage fuel main fuel flow rate Qa And the first stage pilot fuel flow Qb
Only normal operation. As described above, the gas turbine combustor according to the present invention is not limited to the second stage fuel main fuel supply system.
Branch and provide a branch fuel supply system
Install a fuel valve for the second-stage fuel main fuel branch in the fuel supply system
When a back flame occurs in the premixed duct, the second stage
Second stage fuel main fuel provided in the fuel main fuel supply system
Close the fuel valve for the second-stage fuel
Since a switching mechanism for opening the valve is provided, the second stage fuel main
The counterflow flame can be extinguished by closing the fuel valve for fuel.
To open the second-stage fuel main fuel branch fuel valve.
Therefore, the operation of the gas turbine can be continued without
Output can be maintained high . When the fire extinguishing is confirmed by the sensor,
The supply of fuel to the premixed fuel injection nozzle is started again, and the state is set to the lowest NOx state while avoiding the flashback condition stored in the storage device, thereby improving the reliability of the low NOx gas turbine combustor. This has the effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram showing one embodiment of a gas turbine combustor according to the present invention. FIG. 2 is a diagram showing a relationship between a gas turbine load and each fuel flow rate in the embodiment of FIG. FIG. 3 is a view showing a relationship between a gas turbine load and equivalent ratios of respective parts in the embodiment of FIG. 1; FIG. 4 is a diagram showing a relationship between a lapse of time and a flow rate of each fuel when a flashback occurs. FIG. 5 is a diagram showing the relationship between the passage of time and the equivalent ratio of each part when a flashback occurs. FIG. 6 is a diagram showing the relationship between the passage of time and each fuel flow rate when flashback occurs in another embodiment. FIG. 7 is a diagram showing the relationship between the passage of time and the equivalent ratio of each part when flashback occurs in another embodiment. FIG. 8 is a configuration diagram showing a combustor liner of a general gas turbine combustor. FIG. 9 is a system diagram showing a configuration of a conventional gas turbine combustor. FIG. 10 is a diagram showing a relationship between a lapse of time and a fuel flow rate when a flashback occurs in a conventional example. [Description of Signs] 1 Combustion air 2 Fuel 2a Second stage fuel main fuel 2b First stage fuel pilot fuel 2c Branch second stage fuel main fuel 3 Premix duct 5 Combustor liner 6 Combustion chamber 7 First stage fuel nozzle (Pilot fuel nozzle) 10 Second-stage fuel main fuel distribution valve 11 First-stage fuel pilot fuel distribution valve 12 Premixed fuel injection nozzle (main fuel nozzle) 13 Flashback detection sensor 17 Flashback analysis device (storage means) 18 fuel switching valve (switching mechanism) 19 second stage fuel main fuel supply system 20 branch fuel supply system 21 second stage fuel main fuel fuel valve 22 second stage fuel main fuel branch fuel valve 23 first stage fuel pilot fuel Supply system

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-79914 (JP, A) JP-A-6-257467 (JP, A) JP-A-5-322169 (JP, A) JP-A-1- 139919 (JP, A) JP-A-63-311025 (JP, A) JP-A-5-149544 (JP, A) JP-A-2-72334 (JP, U) JP-B-63-8373 (JP, B2) (58) Field surveyed (Int.Cl. ⁷ , DB name) F02C 1/00-9/58 F23R 3/00-7/00

Claims (1)

(1) A first-stage fuel nozzle for injecting a first-stage fuel pilot fuel into a combustion chamber and diffusing and mixing with air to diffuse and burn; a second-stage fuel main fuel and air A premixing duct for premixing and supplying the premixed gas to the combustion chamber, and a premixed fuel injection nozzle disposed at an inlet of the premixing duct and injecting the premixed gas flow into the combustion chamber. A first-stage fuel pilot fuel supply system for supplying a first-stage fuel pilot fuel to the first-stage fuel nozzle, and a second-stage fuel main fuel supply for supplying a second-stage fuel main fuel to the premixed fuel injection nozzle System, a sensor for detecting a backflow flame flowing backward from the combustion chamber into the premix duct, a backfire analysis device for storing the presence or absence of a backflow flame based on a detection signal from the sensor, When the flame flows back from the combustion chamber into the premixing duct, the flashback occurs when the flame is branched from the fuel main fuel supply system and supplies the second-stage fuel main fuel to the first-stage fuel nozzle. The second-stage fuel main fuel supply valve provided in the second-stage fuel main fuel supply system is closed based on the output signal of the analyzer, and the second-stage fuel main fuel branch provided in the branch fuel supply system is closed . A gas turbine combustor comprising a switching mechanism for opening a fuel valve.