JPS6149136A - Operation control method of gas turbine - Google Patents

Abstract

PURPOSE:To reduce the concentration of NOX in exhaust gas, by setting a proportion of pilot fuel to 25-50% when the operation only supplying pilot fuel is transferred to the operation supplying the pilot fuel mixing in main fuel. CONSTITUTION:A gas turbine provides the first fuel nozzle 2 supplying pilot fuel and the second fuel nozzle 5 supplying main fuel to a combustor 1. The turbine, when its operation is transferred from a 30-60% load only supplying pilot fuel to a 100% load, sets a proportion of the pilot fuel to mixed fuel to 25-50%. In this way, concentration of NOX in exhaust gas of the gas turbine can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling the operation of a gas turbine, which aims to reduce NOx in exhaust gas and improve combustion efficiency.

[Conventional technology]

BACKGROUND ART In gas turbines and jet engines, it is important to improve their combustion efficiency and to reduce NOx in exhaust gas. FIG. 1 schematically shows the configuration of the main parts of a gas turbine developed for this purpose, and 1 is a combustor.

The first fuel nozzle 2 supplies pilot fuel to the combustor 1, and its supply is controlled by a valve 3. And this pilot fuel is
It is mixed with primary air taken in through a swirler 4 provided close to the nozzle 2 and combusted. In addition, a second
The fuel nozzle 5 supplies main fuel, and its supply is controlled by a valve 6.

This main fuel is mixed with secondary air taken in via a swirler 7 provided close to the nozzle 5 and combusted. A complete combustion chamber is provided downstream of the main fuel combustion section in order to achieve complete combustion of the fuel. Bypass air whose ω is adjusted is supplied, and this bypass air is used to achieve complete combustion of the fuel. It should be noted that each of the swirlers 4, 7.8 mentioned above means an air introduction hole, and does not define the shape of the hole. Further, the bypass valve has an opening angle of Oo(
The opening is variable from 90° (fully open) to 90° (fully open).

[Problem that the invention seeks to solve]

The gas turbine configured in this manner achieves low N and Ox exhaust gas in normal operating conditions. However, in order to maintain the above-mentioned low NOx in the exhaust gas over the entire range of load fluctuations from the time the gas turbine ignites and starts to its 100% load operating state, it is necessary to control the operation according to the load state. It is necessary to. Also this low N
In order to maintain Ox and increase its combustion efficiency, it is necessary to control the operation of the gas turbine according to the load state of the gas turbine.

However, the actual situation is that the above-mentioned operation control of the Mizozo gas turbine is still carried out on a trial and error basis, and the operation control of the gas turbine that can maintain the above-mentioned low NOx and improve its combustion efficiency. Development of this method is strongly desired.

The present invention was made in response to such demands.
The pilot fuel, main fuel, and bypass air amount are appropriately set according to the operating load status of the gas turbine to maintain optimal combustion conditions for the gas turbine, while maintaining low NOx in the exhaust gas and improving combustion efficiency. It is an object of the present invention to provide a method for controlling the operation of a gas turbine that can be used to control the operation of a gas turbine.

[Means to achieve the purpose]

The present invention mixes primary air with pilot fuel in a combustor and combusts it, mixes secondary air with main fuel and combusts it, and mixes this combustion fuel with bypass air supplied via a bypass valve. When operating the gas turbine to completely burn the fuel, the gas turbine is operated by supplying only the pilot fuel from the time of ignition startup of the gas turbine to the time of 30 to 60% load operation of the gas turbine, 30-60% of the above gas turbines
Between the load operation state and the 100% load operation, the pilot fuel and the main fuel are mixed and supplied to operate the gas turbine, and when the operation state is changed, the bypass valve is fully opened, and the The gas turbine is characterized in that the operation of the gas turbine is controlled by setting a mixing ratio of the pilot fuel to a mixed fuel of pilot fuel and main fuel to 25 to 50%.

[Function of the invention and its effects]

Thus, according to the present invention, only the pilot fuel is combusted during the 30 to 60% load operation state from the time of ignition start, depending on the operating load state of the gas turbine, so that the pilot fuel can be combusted with sufficient efficiency. Hey, Noxil
The gas turbine can be operated without incurring an increase in temperature. When the load is further increased from 30 to 60% load operation, the main fuel is also supplied for mixed combustion, but at this time the bypass valve is fully opened to take in a large amount of bypass air, and the pilot fuel is Since the mixing ratio is set to 25 to 50%, it is possible to completely carry out the combustion without causing an increase in the NoxG degree.

Therefore, regardless of the operating load state of the gas turbine, it is possible to efficiently and completely burn the supplied fuel to improve combustion efficiency, and to stably maintain a low NOx state in the exhaust gas.

〔Example〕

Hereinafter, the operation control method of the present invention will be explained with reference to the operating state diagram of the gas turbine shown in FIG.

FIG. 2 shows the relationship between the ratio of supplied fuel and the opening angle of the bypass valve with respect to the operating load state of the gas turbine. Note that the above-mentioned fuel ratio indicates the ratio of the supplied fuel in the combustion fuel consisting of the supplied reservoir material and the supplied air.

However, during the period after the gas turbine is ignited and started until its operating state reaches 30 to 60% load, or during that operating state, the valve 6 is closed and the main fuel supply is stopped. Only pilot fuel is supplied. This state is shown as the state of area A in FIG. At this time, the state of the bypass valve may be arbitrary, but it is generally preferable to set it to the 0° (fully open) state so that bypass air is not taken in. In other words,
Complete combustion of the supplied pilot fuel is possible without introducing bypass air, and the combustion efficiency can be maintained at a high level.

When the gas turbine is operated at an even higher load, the combustion mode using the pilot fuel and the main fuel is switched to, for example, at a point in the 30% to 60% load operating state, for example, in the 30% load operating state. . This combustion mode is called premix combustion, and is carried out by opening the valve 3.6, and is shown as the region B condition in FIG. The mixing ratio of the pilot fuel during this premix combustion is based on air column resonance, flash bag, N'Ox
, UHC, Co, and its pattern factors, it is desirable to set it to 25 to 50%. Then, when transitioning from the pilot fuel only combustion state to the premixed combustion state, the bypass valve is set to the state 901 (fully open), and a large amount of bypass air is taken in to achieve complete combustion of the mixed fuel.

In other words, at the time of this combustion mode transition, main fuel is supplied in addition to pilot fuel, which may result in incomplete combustion of the mixed fuel, but this can be avoided by mixing the bypass air. Burn completely. Therefore, even during this transition to the combustion mode, the supplied fuel is completely combusted, and the NoxFIi degree in the exhaust gas is suppressed to a low level. The combustion efficiency is also maintained high.

After that, if you want to further increase the load on the gas turbine,
The above-mentioned premix combustion may be maintained as it is, but the gas turbine may be operated by supplying only the main fuel as shown in the head area C in FIG. 2. In this case, it is preferable to start operating the gas turbine after the load reaches 60% or more. At this time, the bypass valve, which was fully open during the transition to the combustion mode, is gradually narrowed down as the operating load increases, that is, the amount of bypass air is gradually reduced, and the main fuel supply port is gradually increased. A gas turbine may also be operated.

If such operation control is performed, the NOx degree can be kept low even under high load, as shown in FIG. 3, which shows the NOx ratio in the exhaust gas.

Furthermore, since 1q of combustion fuel is completely combusted by supplying bypass air, the combustion efficiency can be maintained as high as, for example, 99.5% or more. Further, combustion disturbances such as air column resonance and flashback are not caused, and the pattern factor can be maintained well.

In addition, here, the operation mode was set to shift at a load operating state of 30 to 60%, but if the operation mode is shifted at a range other than the load state mentioned above, it may result in an increase in NoxQ level or a decrease in combustion efficiency. It was confirmed that various necessary performances could not be obtained, such as causing deterioration. Therefore, it can be said that it is important to control the operation mode under the above load conditions.

Although the operation control method of the present invention has been described above, it goes without saying that the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the outline configuration of the main parts of the gas turbine, Fig. 2 is a diagram showing the transition process of the operating state of the gas turbine, and Fig. 3 is a diagram showing the transition process of the operating state of the gas turbine.
It is a figure which shows the change of 111 degrees. 1...Combustor, 2.5...Fuel nozzle, 3,6...
・Valve, 4.7.8...Swirler. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] The pilot fuel is mixed with primary air and combusted, and the main fuel is mixed with secondary air and combusted, and this combusted fuel is mixed with bypass air supplied via a bypass valve to completely burn the fuel. When operating a gas turbine equipped with a combustor configured as above, the gas turbine is operated by supplying only the pilot fuel from the time of ignition startup of the gas turbine to the time of 30 to 60% load operation of the gas turbine, and Between the 30 to 60% load operation state of the gas turbine and the 100% load operation of the gas turbine, the pilot fuel and main fuel are mixed and supplied to operate the gas turbine, and at the time of transition to this operation state, the bypass valve is fully opened. A method for controlling the operation of a gas turbine, characterized in that the ratio of the pilot fuel to the mixed fuel is set to 25 to 50%.