JPH03249337A - Fuel feeding method and device for gas turbine engine - Google Patents

Abstract

PURPOSE:To prevent a quenching phenomenon from occurring in an engine by determining a minimum fuel supply for keeping a flame in a combustor on the basis of air flow, temperature and pressure at a combustor inlet, and making a fuel supply so as to become more than the minimum fuel supply. CONSTITUTION:A function generator 52 operates a minimum fuel supply Gfmin on the basis of air temperature Ta, pressure Pa and flow Ga detected by a sensor 40 installed in an inlet of a combustor 38, outputting a signal in a level commensurate to it. A fuel supply signal generator 60 emits a fuel supply signal conformed to the operated variable of a pedal. When the level of this fuel supply signal goes more down than that of the minimum fuel supply signal, an electric current flows toward a fuel injection pump 44 with a modulator from the generator 52 till values of electric potential between a cathode and an anode of a diode 58 for lower limit value becomes equalized, through which a fuel supply signal level is restricted so as not to become less than the mini mum fuel supply signal level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for supplying fuel to a gas turbine engine, and more particularly to a method and apparatus for supplying fuel to a gas turbine engine equipped with a heat exchanger.

[Prior Art and Problems to be Solved by the Invention 3 A fuel supply system for a gas turbine engine, which is the basis of the present invention, is described in Japanese Patent Application Laid-Open No. 50-31211. This fuel supply system responds to the deviation between the electrical signal corresponding to the actual engine speed and the electrical signal corresponding to the desired engine speed to prevent flame-out and stalling of the gas turbine engine. A lower limit value for the amount of fuel to be supplied is set.

Further, in British Patent No. 946111, upper and lower limits of the fuel supply amount are set in order to prevent flame-out and stall of the gas turbine engine.

These upper and lower limits are corrected by the intake air temperature T and the engine speed Na, or by adding the compressor pressure P at the combustor inlet. The reason for using the intake air temperature T is to take into account the temperature state of the atmosphere.During steady operation, the temperature of the air at outside temperature rises due to the compression of the compressor, and the intake air temperature T at the combustor inlet reaches a maximum. The temperature will be around 400℃.

As shown in FIG. 4, the combustor of a gas turbine engine has a cylindrical casing 10 with a bottom, and a combustor with a bottom that is housed in the casing 10 so that a space is formed between the casing 10. A cylindrical liner 12 is provided. A fuel injection valve 16 is attached to penetrate the bottom surface of the casing 10. Further, a swirler 14 for mixing primary air and fuel is attached to the bottom surface of the liner 12, and this swirler 14 is connected to a fuel injection port of a fuel injection valve 16. A plurality of circular secondary air introduction ports 18 for introducing secondary air into the liner 12 are bored at predetermined intervals along the circumferential direction on the side wall surface of the swirler 14 of the liner 12. Further, a circular dilution air inlet 2 for introducing dilute air is provided on the side wall surface of the combustor outlet 22 of the liner 12.
A plurality of 0's are bored at predetermined intervals along the circumferential direction.

A spark plug 26 is attached so as to penetrate the side wall of the casing 10 and protrude into the liner 12.

The space formed between the liner 12 and the casing 10 acts as an air passage 24 through which air passes.

According to this combustor, compressed air (combustion air) is released from the air passage 24 between the casing 10 and the liner 12.
is supplied. A compressor is used to compress air. This air is supplied into the liner 12 as primary air by the swirler 14, as secondary air through the secondary air inlet 18, and as dilution air through the dilution air inlet 20. Ru.

The fuel injected from the fuel injection valve 16 is mixed with primary air, which is a swirling flow supplied by the swirler 14, and is ignited by the spark plug 26 to undergo primary combustion. This secondary combustion mixture is subjected to secondary combustion by secondary air supplied from the secondary air inlet 18, and the dilution air inlet 20
The average temperature of the combustion gas is lowered to a temperature suitable for supplying it to the turbine, and the temperature distribution of the combustion gas at the combustor outlet 22 is made uniform, so that the combustion gas is diluted by the dilution air supplied from the combustor outlet 22. It is discharged.

This combustion gas then drives the turbine.

Extinguishing of the combustion gas in the liner 12 occurs when the flame is blown away by the air when the air flow velocity becomes too high compared to the flame propagation velocity in secondary combustion and secondary combustion.

However, the above-mentioned conventional gas turbine engine is a gas turbine engine that does not use a heat exchanger to heat the air.
While the temperature change of the air supplied to the combustor is relatively small, the automotive gas turbine engine that is the subject of the present invention has a heat exchanger that further heats the compressed air and supplies it to the combustor. Since the combustor is provided upstream of the combustor, the air temperature at the combustor inlet changes significantly. Therefore, the flammability limit is completely different compared to a gas turbine engine without a heat exchanger. In other words, since the air temperature at the combustor inlet does not correspond to the engine speed and varies greatly depending on the conditions, for example, when decelerating from high-speed, high-load operation to idle, the flammability limit is on the fuel deceleration line. There is a problem in that the flame is blown out and extinguishment occurs.

The present invention has been made to solve the above problems, and provides a fuel supply method and method for supplying fuel to a gas turbine engine using air compressed and heated by a compressor, a heat exchanger, etc., so as not to cause flame-out. An object of the present invention is to provide a fuel supply device that prevents the occurrence of flame-out in a gas turbine engine equipped with a heat exchanger.

[Means to solve the problem]

In order to achieve the above object, the fuel supply method for a gas turbine engine of the present invention supplies compressed and heated air and fuel to a combustor, mixes and combusts the air in the combustor, and generates combustion. When supplying fuel to a gas turbine engine that drives a turbine with gas, a minimum fuel supply amount that does not extinguish the flame in the combustor is determined based on the air flow rate, air temperature, and air pressure at the inlet of the combustor. It is characterized in that the amount of fuel supplied is determined to be equal to or greater than the minimum amount of fuel supplied.

Further, the fuel supply device for a gas turbine engine of the present invention includes a compressor that compresses air, a heat exchanger that heats the air compressed by the compressor, and a system that combines the air heated by the heat exchanger and the supplied fuel. A fuel supply device for a gas turbine engine that supplies fuel to a gas turbine engine, which includes a combustor that mixes and combusts the combustor, and a turbine that is driven by the combustion gas generated in the combustor. a flow rate detection means for detecting the flow rate of supplied air and outputting flow rate information; a temperature detection means for detecting the temperature of the air at the combustor inlet and outputting temperature information; and a temperature detection means for detecting the pressure of the air at the combustor inlet. pressure detection means for outputting pressure information; minimum fuel supply amount determining means for determining a minimum fuel supply amount at which the flame in the combustor will not go out from the flow rate information, the temperature information, and the pressure information; The present invention is characterized in that it includes fuel control means for controlling the fuel supply amount so that the fuel supply amount is equal to or greater than the minimum fuel supply amount based on the output from the fuel supply amount determining means.

[Effect]

The present invention will be explained in detail below. According to an experiment conducted by the present inventors in which compressed and heated air was supplied to the combustor shown in FIG. Similarly to the temperature Ta of the air at the inlet of the combustor, it varied greatly depending on the pressure Pa of the air at the inlet of the combustor. Figure 5 shows the case where the air temperature Ta is 320°C,
As the air pressure Pa increases, the flammable range expands, that is, the flame extinguishing range decreases. Figure 6 shows the case where the air pressure Pa is 2 kg/crl, and as the air temperature Ta increases, the flammable range expands.
In other words, the anti-inflammatory range is reduced. However, the expansion of the flammable range as the air temperature Ta increases is greater than the expansion of the flammable range as the air pressure Pa increases. Therefore, in a gas turbine engine that compresses and heats air, the temperature of the air at the combustor inlet Ta (
During steady operation, approximately 400℃ to 700℃), air flow rate G
A etc. must be taken into account. That is, the minimum value of the fuel supply amount must be determined in consideration of the flow rate Ga of air supplied to the combustor, the temperature Ta and pressure Pa of the air.

As mentioned above, the fuel supply method of the present invention takes into account the temperature and pressure of the compressed and heated air before being supplied to the combustor, and the flow rate when it is supplied to the combustor. Therefore, it is possible to appropriately judge the state of the flame in the combustor and determine the minimum amount of fuel to be supplied without extinguishing the flame.

In the present invention, the compressor compresses air, and the heat exchanger heats the compressed air. The combustor mixes air heated by the heat exchanger and fuel supplied from the fuel supply device and combusts the mixture. The turbine is driven by the combustion gas generated within the combustor.

At the combustor inlet, there is a temperature detection means that detects the temperature of the air and outputs temperature information, a pressure detection means that detects the pressure of the air and outputs pressure information, and a flow rate sensor that detects the flow rate of the air at the combustor inlet. A flow rate detection means is provided for outputting information. The minimum fuel supply amount determination means determines the minimum fuel supply amount at which the flame within the combustor is not extinguished from the temperature information, pressure information, and flow rate information.

In other words, in the fuel supply device of the present invention, air that has been compressed by a compressor and further heated by a heat exchanger is supplied to the combustor at any temperature and pressure, Since the flow rate is taken into account, it is possible to appropriately judge the state of the flame in the combustor and determine the minimum fuel supply amount that will not extinguish the flame.

〔Effect of the invention〕

As explained above, according to the present invention, the minimum fuel supply amount is determined based on the air flow rate, air temperature, and air pressure supplied to the combustor, and the fuel supply amount is set to be equal to or greater than the minimum fuel supply amount. Therefore, it is possible to prevent flame-out in a gas turbine engine that performs combustion using compressed and heated air over the entire operating range.

In addition, it is possible to eliminate flame instability caused by flame extinguishing from ignition at the time of starting the gas turbine engine to idling, thereby achieving the effect that smooth startability can be achieved.

〔Example〕

A first embodiment of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, a compressor 30 for compressing air is connected to a turbine 32 driven by combustion gases. In addition, the output shaft 3 corresponds to the turbine 32.
A power turbine 34 with 6 is arranged. A combustor 38 is arranged to supply combustion gas to the turbine 32, and a heat exchanger is provided upstream of the combustor 38 for heating air with the combustion gas supplied via the turbines 32 and 34. 42 are arranged.

Combustor 38 is similar to that shown in FIG.

At the inlet of the combustor 38, the temperature of the air is Ta.

A sensor 40 is attached to detect air pressure Pa and air flow rate Ga. The temperature Ta, pressure Pa, and flow rate Ga detected by the sensor 40 are the minimum fuel supply amount Gfm.
A Gf+nin function generator 52 generates a signal corresponding to in and a Gf+nax function generator 50 generates a signal corresponding to maximum fuel supply IGfmax. The inventors carried out experiments on flame extinguishing by supplying compressed and heated air to the combustor shown in Figure 4.
The inventors determined the minimum fuel supply amount Gfmin based on the air flow rate Ga, the air temperature Ta, and the air pressure Pa, and found that if fuel supply equal to or greater than the minimum fuel supply amount Gfmin was performed, flame extinction would not occur. According to experiments, the optimum value of this minimum fuel supply amount Gfmin was given by the following equation (1).

Gfmin=Kl・Pa”・Ta−3−Ga2・
...(1) However, K1 is a constant.

The constant 1 in the above equation [1] may be determined experimentally, and the constant must be set to 1 after detecting flame extinction in the combustor and setting it to the fuel supply amount just before this flame extinction occurs. may be changed. Moreover, this minimum fuel supply amount Gfmin is
Although it can be determined by the above equation (1), a flame-out sensor that detects flame-out, which will be described later, may be provided, and the fuel supply amount immediately before the flame-out sensor detects flame-out may be set as the minimum fuel supply amount. In addition, the maximum fuel supply amount Gfmax is as follows (2)
It is given by Eq.

Gfmax= (K2-3 ・Ta) ・Ga-(
2) Here, K2 and K3 are positive constants. The constant 2, K3 can be determined through experiments so that the temperature of the combustion gas when combusted at the maximum fuel supply amount G f+nay does not exceed the heat resistance limit temperature of the combustor, turbine, etc.

A 1 storage device 54 is connected to the Gfmin function generator 52 in which 1 is stored as a coefficient for calculating the minimum fuel supply amount. The output end of the Gfmax function generator 50 is connected to the cathode of the upper limit value diode 56, and the output end of the Gfmin function generator 52 is connected to the anode of the lower limit value diode 58. The Gfmax function generator 50 is
Output the signal with the level calculated by equation (2), and
The n-function generator 52 outputs a signal with a level calculated using the above equation (1). The anode of the upper limit value diode 56 and the cathode of the lower limit value diode 58 are connected to the output end of a fuel supply amount signal generator 60 that generates the fuel supply amount signal Gf. The output end of this fuel supply amount signal generator 60 is connected to a fuel injection pump 44 with a flow rate regulator connected to the fuel injection valve 16. Furthermore, a driver controller 62 that outputs a signal according to the amount of depression of the accelerator pedal 64 is connected to the input end of the fuel supply amount signal generator 60 .

The operation of this embodiment will be explained below. The air compressed by the compressor 30 passes through the air passage 46 to the heat exchanger 4.
2 and heated. The air heated by the heat exchanger 42 is supplied to the combustor 38, mixed with fuel injected from the fuel injection valve 16, and combusted as described above. Combustion gas is supplied through combustor 38 and rotates turbine 32 and power turbine 34 before being discharged through heat exchanger 42 .

The G fmax function generator 50 outputs a maximum fuel supply amount signal at a level calculated according to the above equation (2) based on the air temperature Ta detected by the sensor 40 and the flow rate Ga. The Gfmin function generator 52 calculates the minimum fuel supply amount according to the above equation (1) based on the air temperature Ta, pressure Pa, and flow rate Ga detected by the sensor 40, and sets the level corresponding to the minimum fuel supply amount. Output a signal. The fuel supply amount signal generator 60 generates a fuel supply amount signal according to the amount of depression of the accelerator pedal 64. When the level of the fuel supply amount signal becomes larger than the level of the maximum fuel supply amount, the potential of the anode of the upper limit diode 56 becomes higher than the potential of the cathode, so the potential between the anode and cathode of the upper limit diode 56 increases. A current flows from the fuel supply amount signal generator 60 toward the Gfmax function generator 50 until the Gfmax function generator 50 becomes equal, thereby limiting the level of the fuel supply amount signal from exceeding the level of the maximum fuel supply amount signal. Further, when the level of the fuel supply amount signal falls below the level of the minimum fuel supply amount signal, the potential of the cathode of the lower limit value diode 58 becomes lower than the potential of the anode of the lower limit value diode 58. A current flows from the Gfmin function generator 52 toward the regulator-equipped fuel injection pump 44 until the potentials of the cathode and anode of the diode 58 become equal, and as a result, the level of the fuel supply amount signal becomes the level of the minimum fuel supply amount signal. limited to no less than The regulator-equipped fuel injection pump 44 controls the fuel injection valve 16 using a fuel supply amount signal whose level is limited to a value within a predetermined range by an upper limit value diode 56 and a lower limit value diode 58. Inject fuel inside.

As explained above, according to this embodiment, the fuel supply amount is (
1) Since the fuel supply amount is limited so as not to be less than the minimum fuel supply amount determined by the formula, the occurrence of flame extinguishment is prevented in all operating ranges.

Next, a second embodiment of the present invention will be described. In this embodiment, a flame sensor 70 is provided to detect flame extinction in the combustor, and a G
Gf+mi for changing the magnitude of the minimum combustion supply amount signal between the fmin function generator 52 and the lower limit value diode 58
n change device 72 is provided. The Gfmin changer 72 is composed of a microcomputer. In this embodiment, illustration of the same parts as in FIG. 1 is omitted.

Next, the control routine of the Gfmin changing device 72 will be explained. In step 100, the output of the flame sensor 70 is taken in, and in step 102, the output of the flame sensor 70 is analyzed by frequency analysis using Fourier transform or the like. In the next step 104, it is determined whether or not flame extinction has occurred based on the analysis result of step 102, and when it is determined that flame extinction has occurred, the level of the minimum fuel supply amount signal is determined in step 106 as shown in the following equation. ε (for example, 0.
Increase by 1).

Gfmin←(1'-,E)・Gfmin・(2
) As described above, according to this embodiment, the level of the minimum fuel supply amount signal can be changed depending on whether or not flame-out occurs, and the minimum fuel supply amount can be set to the value of the flame-out occurrence limit.

Note that if it is determined in step 104 that no flame quenching has occurred, if the level of the minimum fuel supply amount signal is decreased according to the following equation (3), the minimum fuel supply amount may become larger than the optimum value due to an error or the like. It is possible to make corrections in the event of a change in fuel consumption, thereby reducing fuel consumption.

Gfmin←(1-e) ・Gfmin-・(3)

[Brief explanation of drawings]

Fig. 1 is a block diagram of a first embodiment of the present invention, Fig. 2 is a block diagram of a second embodiment of the present invention, and Fig. 3 is a flowchart showing a routine for changing the minimum fuel supply amount of the second embodiment. , 4th
The figure is a cross-sectional view of the combustor, Figure 5 is a line diagram showing the relationship between the fuel flow rate and air flow rate when the temperature of the air at the combustor inlet is kept constant, and Figure 6 is a diagram showing the relationship between the fuel flow rate and the air flow rate when the temperature of the air at the combustor inlet is kept constant. FIG. 3 is a diagram showing the relationship between the fuel flow rate and the air flow rate when they are kept constant. 30...Compressor, 32...Turbine, 38...Combustor, 40...Sensor, 42...Heat exchanger.

Claims (2)

[Claims] (1) Compressed and heated air and fuel are supplied to a combustor, mixed and combusted in the combustor, and the generated combustion gas is used to supply fuel to a gas turbine engine that drives a turbine. The minimum fuel supply amount that does not extinguish the flame in the combustor is determined based on the air flow rate, air temperature, and air pressure at the inlet of the combustor, so that the fuel supply amount is equal to or greater than the minimum fuel supply amount. A fuel supply method for a gas turbine engine, characterized in that: (2) a compressor that compresses air; a heat exchanger that heats the air compressed by the compressor; and a combustor that mixes and burns the air heated by the heat exchanger and the supplied fuel; A fuel supply device for a gas turbine engine that supplies fuel to a gas turbine engine, comprising: a turbine driven by combustion gas generated in the combustor; a flow rate detection means for outputting information; a temperature detection means for detecting the temperature of air at the combustor inlet and outputting temperature information; and a pressure detection means for detecting the pressure of the air at the combustor inlet and outputting pressure information. , minimum fuel supply amount determining means for determining a minimum fuel supply amount at which the flame within the combustor does not go out based on the flow rate information, the temperature information, and the pressure information; and based on the output from the minimum fuel supply amount determining means. A fuel supply device for a gas turbine engine, comprising: fuel control means for controlling a fuel supply amount so that the fuel supply amount is equal to or greater than the minimum fuel supply amount.