JPH09178186A - Control method for premixed combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep flame stably by removing the abnormal combustion of a premixed combustion chamber, and lessening the discharge of noxious matter. SOLUTION: This premixed combustion device has such constitution that a premixing chamber 1 for mixing fuel and air, a combustion chamber 2 for combusting the mixed air between fuel and a diluting and mixing chamber 3 for mixing combustion gas and air are connected in order, and that the first fuel injection valve 4 for spraying fuel into the premixing chamber 1, the second fuel valve 5 for spraying fuel into the combustion chamber 2, and an air supply passage 6 for supplying air to the premixing chamber 1, the diluting and mixing chamber 3, or the combustion chamber are provided. Then, if the system detects the combustion generated in the premixing chamber 1, this extinguishes the combustion flame of the premixing chamber 1, by reducing the flow of the fuel to be sprayed into the premixing chamber 1, or increasing the flow of air to be supplied to the premixing chamber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling combustion in a premixed combustion device in which fuel and air are premixed and burned.

[0002]

2. Description of the Related Art In a premix combustion system, fuel and air are premixed in a premix chamber and the mixture is burned in the combustion chamber.
Compared to the diffusion combustion method in which fuel is directly sprayed into the combustion chamber and burned, the air-fuel mixture in the combustion chamber is essentially uniform and the combustion temperature tends to be uniform, and the high temperature region is small
Generation of O _x is small. Even in the premixed combustion method, lean combustion is performed by increasing the excess air ratio of the air-fuel mixture in the combustion chamber in order to suppress the generation of thermal NO _x . However, if the excess air ratio of the air-fuel mixture in the combustion chamber becomes too large, the production of carbon monoxide CO and unburned hydrocarbons HC will increase rapidly, and the combustion flame in the combustion chamber will become unstable and blow off.
On the contrary, if the excess air ratio in the combustion chamber becomes too small, abnormal combustion such as flashback or spontaneous combustion occurs in the premixing chamber. The premix combustion system has a narrow range of excess air ratio in the combustion chamber in which abnormal combustion in the premix chamber does not occur, harmful substances are discharged, and the flame is stable. Therefore, it is generally difficult to satisfy the performance required for the combustion device of the gas turbine engine having a wide load variation range.

In a regenerative gas turbine engine,
In order to improve the fuel consumption rate, the gas temperature at the turbine inlet, that is, the combustor outlet is increased to 1000 to 1400 ° C., and the air supplied to the combustor is heated by the gas discharged from the turbine to increase the air temperature at the combustor inlet. Studies have been conducted to raise the temperature to 600 to 1000 ° C.

In the premixed lean combustion system, when the air temperature at the inlet of the combustion apparatus rises to 600 to 1000 ° C., the combustion flame in the combustion chamber is maintained at a relatively uniform temperature of about 1500 ° C. or higher, and harmful substances are discharged. It is considered that the flame is stable and there is little. However, abnormal combustion such as flashback or spontaneous combustion is likely to occur in the premix chamber.

Therefore, in order to prevent abnormal combustion in the premix chamber, it is conceivable to raise the lower limit of the allowable range of the excess air ratio of the combustion chamber. It becomes increasingly difficult to cope with large load fluctuations of turbine engines.

Further, if the combustion flame in the combustion chamber is maintained at a temperature of about 1500 ° C. or higher, the gas temperature at the outlet of the combustion chamber exceeds the heat resistant temperature of the turbine, which is about 1400 ° C. at maximum.
The combustion gas discharged from the combustion chamber is diluted by mixing air in the dilution mixing chamber so that the gas temperature at the outlet of the combustion chamber becomes equal to or lower than the heat resistant temperature of the turbine.

Regenerative gas turbine engines for automobiles are
Wide load fluctuation range and wide fluctuation range of fuel flow rate of the combustion device.

The premixed lean combustion system for a regenerative gas turbine engine for automobiles is designed to reduce the emission of harmful substances and maintain a stable flame over a wide load variation range. It is necessary to control the air flow rate optimally. If the rate at which the air supplied to the air passage is divided into combustion air and dilution air is fixed, the combustion air flow rate cannot be optimally controlled.

Further, when the fuel flow rate rapidly increases such as at the time of starting or accelerating, in order to prevent abnormal combustion in the premix chamber, a part of the fuel is directly added without increasing the concentration of the air-fuel mixture in the premix chamber. It is injected into the combustion chamber and burned, and combined combustion that combines premixed lean combustion and diffusion combustion is performed. However, the larger the ratio of the fuel premixed with the air in the premix chamber, the more uniform the air-fuel mixture in the combustion chamber, and the less the generation of thermal NO _x .
In order to increase the proportion of fuel to be premixed, it is necessary to optimally control the flow rate of combustion air supplied to the premix chamber.

[0010]

However, in some of the conventional premixing combustion devices, it is difficult to cause abnormal combustion in the premixing chamber, but abnormal combustion does not occur at all.
It does not prevent abnormal combustion.

In controlling combustion in the combustion chamber,
In addition to not accurately detecting the combustion state of the combustion chamber, the distribution ratio of the combustion air supplied to the premix chamber and the dilution air supplied to the dilution mixing chamber is fixed, and the flow rate of the combustion air is not optimally controlled.

Therefore, it is impossible to prevent abnormal combustion in the premixing chamber, reduce the emission of harmful substances, and stably maintain the flame.

[0013]

[Observation for solving the problem] The abnormal combustion flame generated in the premixing chamber causes premixing when the flow rate of fuel sprayed into the premixing chamber is decreased and when the flow rate of air supplied to the premixing chamber is increased. The concentration of the air-fuel mixture in the chamber becomes low and the fire is extinguished.

Since the combustion temperature in the premixed lean combustion becomes almost uniform, it can be controlled based on the combustion temperature.
However, a combustion temperature of about 1500 ° C. or higher cannot be directly detected by a conventional temperature sensor such as a thermocouple.

However, the air temperature at the inlet of the air passage is 30
When the operating condition of the inlet of the combustion device is within a certain range, such as when the temperature is about 0 ° C. or higher, the combustion temperature of the combustion chamber is almost determined from the air temperature at the inlet of the air passage and the average excess air ratio of the combustion chamber. Therefore, it is possible to obtain the average excess air ratio of the combustion chamber and perform control based on the average excess air ratio. Further, the combustion temperature of the combustion chamber can be obtained from the average excess air ratio and the air temperature at the inlet of the air passage, and control can be performed based on this combustion temperature.

When the combustion load increases, as in the case of combined combustion in which premixed lean combustion and diffusion combustion are combined, the pressure loss of the combustion device increases. Therefore, due to this pressure loss, etc., the average excess air ratio of the combustion chamber is increased. Can be asked. Also, the combustion temperature of the combustion chamber can be obtained.

[0017]

A premixing chamber for mixing fuel and air, a combustion chamber for burning a mixture of fuel and air, and a diluting mixing chamber for mixing combustion gas and air are sequentially connected to each other to form a premixing chamber. Premixed combustion in which a first fuel injection valve for spraying fuel and a second fuel injection valve for spraying fuel in the combustion chamber are provided, and an air passage for supplying air to the premixing chamber and the dilution mixing chamber or the combustion chamber is provided In the device, when the combustion generated in the premixing chamber is detected, the flow rate of the fuel sprayed into the premixing chamber is decreased, or the flow rate of the air supplied to the premixing chamber is increased, or
A control method comprising extinguishing a combustion flame in a premixing chamber by decreasing a flow rate of fuel sprayed in the premixing chamber and increasing a flow rate of air supplied to the premixing chamber.

By detecting the state quantity of the combustion flame in the combustion chamber, or by detecting the flow rate of fuel supplied to both fuel injection valves, the flow rate of air supplied to the air passage, the air pressure at the air passage inlet, and the dilution mixing chamber outlet. By detecting the combustion gas pressure and the air temperature at the inlet of the air passage, the average excess air ratio of the combustion chamber is obtained.When the average excess air ratio is smaller than the lower limit of the desired range, the flow rate of the air supplied to the premix chamber is set. When the average excess air ratio increases and the average excess air ratio is larger than the upper limit value of the desired range, the flow rate of the air supplied to the premix chamber is decreased to bring the average excess air ratio of the combustion chamber into the desired range. Control method.

The average amount of excess air in the combustion chamber is determined by detecting the state quantity of the combustion flame in the combustion chamber, and the flow rate of the air supplied to the air passage, the air pressure at the inlet of the air passage, and the combustion gas pressure at the outlet of the dilution mixing chamber are calculated. The air temperature at the inlet of the air passage is detected to obtain the combustion temperature of the combustion chamber.When the combustion temperature is lower than the lower limit value of the desired range, the flow rate of the air supplied to the premix chamber is reduced so that the combustion temperature becomes the desired value. When it is larger than the upper limit value of the range, the flow rate of the air supplied to the premixing chamber is increased to bring the combustion temperature of the combustion chamber into a desired range.

[0020]

When a combustion flame is generated in the premixing chamber, the flow rate of the fuel sprayed into the premixing chamber is reduced or the flow rate of the air supplied to the premixing chamber is increased to prevent the combustion flame in the premixing chamber. extinguish a fire.

Further, the average excess air ratio or combustion temperature of the combustion chamber is obtained, and the flow rate of the air supplied to the premixing chamber is increased or decreased to bring the average excess air ratio or combustion temperature of the combustion chamber to a desired range.

Therefore, it is possible to prevent abnormal combustion in the premixing chamber, reduce the emission of harmful substances, and stably maintain the flame.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Example (see FIGS. 1 to 10)> [Premixed Combustion Device] A premixed combustion device for carrying out the control method of the present embodiment is a combustion device for an automobile regenerative gas turbine engine.

As shown in FIG. 1, the premix combustion apparatus comprises a premix chamber 1 having a circular ring cross section for mixing fuel and air, a combustion chamber 2 having a circular cross section for burning a mixture of fuel and air. First, a dilution mixing chamber 3 having a circular cross-sectional shape for mixing combustion gas and air is sequentially connected in a concentric manner, and fuel is sprayed into the premixing chamber 1.
A fuel injection valve 4 and a second fuel injection valve 5 for spraying fuel into the combustion chamber 2 are provided, and an air passage 6 having a circular ring cross section for supplying air to the premixing chamber 1 and the dilution mixing chamber 3 is concentric. It is provided.
A device for supplying a liquid fuel such as light oil or kerosene is provided to both the fuel injection valves 4 and 5.

The premixing chamber 1 is provided with an air flow rate adjusting mechanism at its inlet so that the flow rate of the combustion air flowing into the premixing chamber 1 can be increased or decreased.

As shown in FIGS. 1 and 2, the air flow rate adjusting mechanism has a fixed plate 7 and a movable plate 8 at the annular inlet of the premixing chamber 1.
Are arranged so as to overlap with each other, and the fixed plate 7 and the movable plate 8 are penetrated through arc-shaped long holes 9 and 10, respectively, and a part of the long hole 9 of the fixed plate and a part of the long hole 10 of the movable plate are overlapped. And the air in the air passage 6 passes through the communicating portions of both the long holes 9 and 10 and the premix chamber 1
It is configured to flow into. A gear portion 11 is formed concentrically on the outer periphery of the rotatable movable plate 8, and the tip gear portion of the adjusting shaft 12 is meshed with the gear portion 11 of the movable plate 8. The movable plate 8 is rotated by the rotation of the adjusting shaft 12, and the area where the long hole 10 of the movable plate communicates with the long hole 9 of the fixed plate is increased or decreased to increase or decrease the flow rate of the combustion air flowing into the premix chamber 1. .

An air swirl adjusting mechanism is provided between the inlet of the premix chamber 1 and the fuel spray position of the first fuel injection valve 4 to increase or decrease the swirl number of the swirl flow of the combustion air flowing into the premix chamber 1. It is possible.

As shown in FIGS. 1 and 3, the air swirl adjusting mechanism includes a fixed plate 7 and a movable plate 13 in an annular portion of the premix chamber 1.
Are arranged so as to face each other, and the fixed plate 7 and the movable plate 13 are each provided with unevenness in an annular shape, and the unevenness of the fixed plate 7 and the unevenness of the movable plate 13 are engaged with each other. The non-turning passage 16 along the radial direction is formed between the side surfaces of the movable plate convex portion 15 of FIG. 1 and the side surface of the other side of the fixed plate convex portion 14 and the side surface of the movable plate convex portion 15 adjacent thereto. The swirl passages 17 are formed along the direction, and the air flowing into the premix chamber 1 passes through the non-swirl passage 16 and the swirl passage 17. On the outer circumference of the rotatable movable plate 13, there is a gear part 18
Are formed concentrically, and the adjustment shaft 1 is attached to the gear portion 18 of the movable plate 13.
The tip gear part of 9 is meshed. The rotation of the adjusting shaft 19 causes the movable plate 13 to rotate, thereby narrowing or widening the width of the non-swirl passage 16 and widening or narrowing the width of the swirl passage 17 so that the combustion air flowing into the premixing chamber 1 is obtained. Increase or decrease the swirl number of swirl flow.

A first flame detection device is provided downstream of the fuel spray position of the first fuel injection valve 4 in the premix chamber 1 and
It is possible to detect the combustion flame generated in the.

The first flame detecting device, as shown in FIG.
The front end of the light passage 20 with a wide-angle lens, such as an optical fiber having high heat resistance, is arranged in the premix chamber 1, and the base end of the light passage 20 is connected to a light detection element 21 such as a photodiode or a phototransistor. There is. When a combustion flame is generated in the premix chamber 1, the photo detection element 21 outputs.

As shown in FIG. 1, the combustion chamber 2 has a second fuel injection valve 5 concentrically provided on the inlet side, and a second flame detection device incorporated therein to determine the state quantity of the combustion flame in the combustion chamber 2. Detectable.

The second flame detecting device, as shown in FIG.
The fuel passage 22 at the axial position of the second fuel injection valve 5 penetrates the optical passage 23 such as an optical fiber having high heat resistance,
3 is disposed in the atomizing air passage 24 and the ejection hole 25 at the center thereof, and the tip of the optical passage 23 with the wide-angle lens is projected from the ejection hole 25 of the atomizing air passage into the combustion chamber 2 to The base end of the optical passage 23 protruding from the passage 22 is connected to a photodetector element 26 such as a phototransistor. When the combustion flame is generated in the combustion chamber 2, the light detection element 26 outputs a signal according to the state quantity of the combustion flame.

As shown in FIG. 1, the combustion chamber 2 is provided with an ignition plug 27 for igniting the air-fuel mixture.

The regenerative gas turbine engine for automobiles is
A gas turbine and a heat radiating passage of a heat exchanger are sequentially connected to the exit of the dilution mixing chamber 3 of the premix combustion apparatus, and a heat receiving passage of the heat exchanger and an air compressor are sequentially connected to the inlet of the air passage 6 of the premix combustion apparatus. The shaft of the gas turbine and the shaft of the air compressor are connected.

[Control Method] The control method of the present example is the combustion chamber 2
And a method of controlling abnormal combustion in the premix chamber 1.

There are two examples of methods for controlling the combustion in the combustion chamber 2; a control method based on the average excess air ratio of the combustion chamber 2 and a control method based on the combustion temperature of the combustion chamber 2.

1) Method of controlling combustion in the combustion chamber based on the average excess air ratio in the combustion chamber In this control method, the combustion temperature of the combustion chamber 2, that is, the flame temperature of premixed combustion is equal to the air temperature at the inlet of the air passage 6. Since it is almost determined from the average excess air ratio of the combustion chamber 2, the average excess air ratio of the combustion chamber 2 is detected and the combustion air flowing into the premix chamber 1 is detected in order to set the combustion temperature of the combustion chamber 2 to the optimum range. Control the flow rate.

The average excess air ratio of the combustion chamber 2 is as follows when the fluctuation of the operating conditions of the combustion device is small as in the steady operation.
Based on the power spectrum ratio of the combustion flame light in the combustion chamber 2, when the operating condition of the combustion device fluctuates significantly during transient operation, detection is performed based on the pressure loss of the combustion device.

A Control Method When Fluctuations in Operating Conditions of Combustion Device are Small The optical powers of the combustion flames output by the second flame detection devices 23 and 26 of the combustion chamber 2 are shown in FIG. 5 when a frequency analysis of the fluctuations is performed. The spectrum looks like this. In this spectrum, the power spectrum A in the frequency range higher than the specific frequency
Then, the ratio B / A of the power spectrum B in the low frequency range is calculated. As shown in FIG. 6, the power vector ratio B / A has a certain correspondence with the average excess air ratio λ of the combustion chamber 2. That is, the average excess air ratio λ of the combustion chamber 2 is obtained based on the power spectrum ratio of the combustion flame light.

In the control method, as shown in FIG. 7, the second flame detecting devices 23 and 26 detect the optical power of the combustion flame in the combustion chamber 2. When the optical power is smaller than the set value, the fuel supply to both fuel injection valves 4 and 5 is stopped and an abnormality alarm is issued.
When the optical power is equal to or higher than the set value, the optical power is subjected to frequency analysis, the power spectrum ratio B / A is calculated, and the average excess air ratio λ of the combustion chamber 2 is calculated.

The average excess air ratio λ is the lower limit value α of the setting range,
In the embodiment, if it is smaller than 3, the adjusting shaft 12 of the air flow rate adjusting mechanism is rotated to increase the flow rate of the combustion air flowing into the premix chamber 1. In addition, the adjustment shaft 19 of the air swirl adjustment mechanism
Is rotated to reduce the swirl number of the swirling flow of the combustion air flowing into the premix chamber 1.

The average excess air ratio λ is the upper limit value β of the set range,
In the embodiment, if it is larger than 5, the adjusting shaft 12 of the air flow rate adjusting mechanism is rotated to reduce the flow rate of the combustion air flowing into the premix chamber 1. Further, in order to prevent the deterioration of the stability of the combustion flame due to the decrease in the flow rate of the combustion air, the swirl number of the swirling flow of the combustion air flowing into the premix chamber 1 is rotated by rotating the adjusting shaft 19 of the air swirling adjusting mechanism. To increase.

B Control Method When Fluctuations in Operating Conditions of Combustor are Large Flow rate Gf of fuel supplied to both fuel injection valves 4 and 5, flow rate Ga of air supplied to air passage 6, air pressure at inlet of air passage 6 When the Pi, the combustion gas pressure Po at the outlet of the dilution mixing chamber 3 and the air temperature Ti at the inlet of the air passage 6 are detected, the average excess air ratio λ of the combustion chamber 2 is obtained from the following equation. Where n
Is the distribution ratio of the air flow rate Ga to the combustion air flow rate. C ₁ and C ₂ are coefficients.

N = 1-C ₁ {Ti (Pi-Po) / Pi} ^1/2 / Ga λ = C ₂ nGa / Gf In an automobile regenerative gas turbine engine, the fuel flow rate Gf is a metering device. Since the amount is adjusted, it is not necessary to newly install a sensor for the fuel flow rate Gf. Further, the rotation speed of the gas turbine, that is, the rotation speed of the air compressor and the outlet pressure of the air compressor are measured, and the outlet flow rate of the air compressor, that is, the air flow rate Ga is obtained from these measured values and the characteristics of the air compressor. It is not necessary to newly install a sensor for the air flow rate Ga. Sensors for the air pressure Pi, the combustion gas pressure Po, and the air temperature Ti are provided respectively.

In the control method, as shown in FIG. 8, the second flame detecting devices 23 and 26 detect the optical power of the combustion flame in the combustion chamber 2. When the optical power is smaller than the set value, the fuel supply is stopped and an abnormal alarm is issued. When the optical power is equal to or higher than the set value, the fuel flow rate Gf, the air flow rate Ga, the air pressure Pi,
The combustion gas pressure Po and the air temperature Ti are detected, and the distribution ratio n
Is calculated to calculate the average excess air ratio λ.

The average excess air ratio λ is the lower limit value α of the setting range,
In the embodiment, when it is smaller than 3, the flow rate of the combustion air flowing into the premixing chamber 1 is increased by the air flow rate adjusting mechanism, and the swirl number of the swirling flow of the combustion air flowing into the premixing chamber 1 is adjusted by the air swirling. Reduced by mechanism.

The average excess air ratio λ is the upper limit value β of the set range,
In the embodiment, when it is larger than 5, the flow rate of the combustion air flowing into the premixing chamber 1 is reduced by the air flow rate adjusting mechanism, and the swirl number of the swirling flow of the combustion air flowing into the premixing chamber 1 is adjusted by the air swirling. Increase with the mechanism.

If the average excess air ratio λ is within the set range, the premixing chamber 1 is adjusted if the average excess air ratio λ of this time is smaller than the previous average excess air ratio λp in order to correct the variation from the previous sampling. The combustion air has an increased flow rate and a reduced swirl number. When the current average excess air ratio λ is larger than the previous average excess air ratio λp, the flow rate of the combustion air in the premix chamber 1 is decreased and the swirl number is increased.

2) Method for controlling combustion in the combustion chamber based on the combustion temperature in the combustion chamber As shown in FIG. 9, this control method is similar to the control method in 1) a above, and the combustion flame in the combustion chamber 2 is the same. The average excess air ratio λ of the combustion chamber 2 is calculated based on the power spectrum ratio of light. Further, in the same manner as the control method of 1) b above, the air passage 6
To the combustion air flow rate in the air flow rate Ga based on the flow rate Ga of the air supplied to the air, the air pressure Pi at the inlet of the air passage 6 The distribution ratio n is calculated. Then, the average combustion temperature T of the combustion chamber 2 is obtained from the following equation. However,
C ₃ is a coefficient.

T = Ti + C ₃ nGa / λ The combustion temperature T is the lower limit value γ of the set range, 1600 in the embodiment.
When the temperature is smaller than ℃, the flow rate of the combustion air flowing into the premix chamber 1 is decreased by the air flow rate adjusting mechanism, and the swirl number of the swirling flow of the combustion air flowing into the premixing chamber 1 is increased by the air swirling adjusting mechanism. To do.

When the combustion temperature T is higher than the upper limit value δ of the set range, 1800 ° C. in the embodiment, the flow rate of the combustion air flowing into the premixing chamber 1 is increased by the air flow rate adjusting mechanism so that the premixing chamber 1 enters the premixing chamber 1. The swirl number of the swirling flow of the inflowing combustion air is reduced by the air swirl adjusting mechanism.

If the combustion temperature T is in the set range γ to δ, the fluctuation from the previous sampling is corrected. Therefore, if the current combustion temperature T is lower than the previous combustion temperature Tp, the combustion temperature in the premixing chamber 1 is reduced. Air reduces flow rate and increases swirl number. When the current combustion temperature T is higher than the previous combustion temperature Tp, the flow rate of the combustion air in the premix chamber 1 increases and the swirl number decreases.

3) Method for controlling abnormal combustion in the premix chamber In this control method, as shown in FIG. 10, the second flame detectors 23 and 26 detect the optical power of the combustion flame in the combustion chamber 2 and After confirming that the optical power is above the set value,
The first flame detection devices 20 and 21 detect the optical power of the combustion flame in the premix chamber 1 and when the optical power is equal to or higher than a set value, an abnormal alarm is issued and the ignition plug 27 of the combustion chamber is ignited. If the second fuel injection valve 5 is stopped, a small flow rate of fuel is sprayed from the second fuel injection valve 5 into the combustion chamber 2, and the second fuel injection valve 5
Is operating, the flow rate of the fuel sprayed from the second fuel injection valve 5 to the combustion chamber 2 is slightly increased, and when the optical power of the combustion flame in the combustion chamber 2 is equal to or higher than the set value, 4, the flow rate of the fuel sprayed into the premix chamber 1 is reduced by the increase in the fuel flow rate of the second fuel injection valve 5. Further, the flow rate of the combustion air flowing into the premix chamber 1 is increased by the air flow rate adjusting mechanism, and the swirl number of the swirling flow of the combustion air flowing into the premix chamber 1 is decreased by the air swirling adjusting mechanism.

As long as the flow rate of the fuel sprayed in the premix chamber 1 does not become zero and the optical power of the combustion flame in the premix chamber 1 is equal to or more than the set value, the combustion flame in the combustion chamber 2 is changed as described above. Combustion chamber 2 while confirming that the optical power is above the set value
Of the fuel sprayed to the combustion chamber 2 and the premix chamber 1 by repeating the increase of the flow rate of the fuel sprayed to the premix chamber 1 and the decrease of the flow rate of the fuel sprayed to the premix chamber 1 and the increase of the flow rate of the combustion air in the premix chamber 1 and the reduction of the swirl number The combustion flame generated in the premixing chamber 1 is extinguished while keeping the total flow rate constant.

If the light power of the combustion flame in the combustion chamber 2 becomes smaller than the set value, and the light power of the combustion flame in the premix chamber 1 is set even if the flow rate of the fuel sprayed into the premix chamber 1 becomes zero. If the value is equal to or more than the value, the supply of fuel to both fuel injection valves 4 and 5 is stopped and an abnormal alarm is issued.

When the combustion flame generated in the premix chamber 1 is extinguished, conversely, the flow rate of the fuel sprayed into the combustion chamber 2 is decreased and the flow rate of the fuel sprayed into the premix chamber 1 is increased to increase the flow rate of the premix chamber 1. The flow rate of combustion air is reduced and the swirl number is increased.

<Second Example (see FIGS. 11 and 12)> As shown in FIG. 11, a premixing combustion apparatus used in a regenerative gas turbine engine for an automobile has a plurality of circular tube-shaped premixing chambers 31, The main combustion chamber 32 and the dilution mixing chamber 33 are sequentially connected,
The auxiliary combustion chamber 34 is connected to the upstream end of the main combustion chamber 32, each premixing chamber 31 is provided with a first fuel injection valve 35, and each auxiliary combustion chamber 34 is provided with a second fuel injection valve 36. An air passage 37 for supplying air to the auxiliary combustion chamber 34, the main combustion chamber 32 and the dilution mixing chamber 33 is provided.

Air inlet of each premixing chamber 31 and auxiliary combustion chamber 3
An air swirling mechanism is provided at each of the four air inlets.

As shown in FIGS. 11 and 12, flame detecting devices are provided at the downstream positions of the premixing chambers 31, respectively.
The combustion flame generated in each premixing chamber 31 can be detected. In the flame detection device, the tip of the light passage 38 with the wide-angle lens is arranged upstream in the central position of the premix chamber 31, and the base end of the light passage 38 is connected to the light detection element 39.

In the auxiliary combustion chamber 34, as shown in FIG.
A spark plug 40 is provided.

The control method of this example is a method of controlling abnormal combustion in the premix chamber. Any flame detection device 38, 3
9 detects the optical power of the combustion flame of the premix chamber 31 and when the optical power is equal to or higher than a set value, an abnormal alarm is issued, the spark plug 40 of the auxiliary combustion chamber 34 is ignited, and the auxiliary combustion chamber 34 The flow rate of the fuel sprayed from the second fuel injection valve 36 is slightly increased, and the flow rate of the fuel sprayed from the first fuel injection valve 35 to the premix chamber 31 in which the combustion flame is generated is increased by the fuel flow rate of the second fuel injection valve 36. Decrease by a minute.

As long as the flow rate of the fuel sprayed into the premixing chamber 31 in which the combustion flame is generated does not become zero and the optical power of the combustion flame in the premixing chamber 31 in which the combustion flame is generated is the set value or more, As described above, the increase in the flow rate of the fuel sprayed into the auxiliary combustion chamber 34 and the decrease in the flow rate of the fuel sprayed into the premixing chamber 31 are repeated to keep the total flow rate of the fuel flows sprayed into the auxiliary combustion chamber 34 and the premixing chamber 31 constant. Then, the combustion flame generated in the premix chamber 31 is extinguished.

Even if the flow rate of the fuel sprayed into the premix chamber 31 in which the combustion flame is generated becomes zero, if the optical power of the combustion flame in the premix chamber 31 is equal to or higher than the set value, all the fuel injection valves 35, The fuel supply to 36 is stopped and an abnormal alarm is issued.

When the combustion flame generated in the premix chamber 31 is extinguished, the flow rate of fuel sprayed into the auxiliary combustion chamber 34 is decreased, and the flow rate of fuel sprayed into the premix chamber 31 is increased.

<Third Example (see FIGS. 13 and 14)> As shown in FIG. 13, a premixing combustion apparatus used in a regenerative gas turbine engine for an automobile has a premixing chamber 41 having a circular ring cross section and a main mixing chamber 41. The combustion chamber 42 and the dilution mixing chamber 43 are sequentially connected, the auxiliary combustion chamber 44 is connected to the upstream end of the main combustion chamber 42, and the first fuel injection valve 45 for spraying fuel into the premixing chamber 41 and the auxiliary combustion chamber 44 are connected. A second fuel injection valve 46 for spraying fuel is provided in the above, and an air passage 47 for supplying air to the premixing chamber 41, the auxiliary combustion chamber 44 and the main combustion chamber 42 is provided.

Air inlet of premixing chamber 41 and auxiliary combustion chamber 44
An air swirling mechanism is provided at each of the air inlets. As shown in FIG. 13, an annular honeycomb catalyst 48 that burns a part of the air-fuel mixture is provided at a position downstream of the premixing chamber 41. As shown in FIGS. 13 and 14, at a position upstream of the catalyst 48 in the premixing chamber 41, a plurality of flame detecting devices in which an optical passage 49 with a wide-angle lens and a photodetecting element 50 are sequentially connected are provided. The combustion flame generated at 41 can be detected. A spark plug 51 is provided in the auxiliary combustion chamber 44.

In the abnormal combustion control method of this example, one of the flame detection devices 49 and 50 detects the optical power of the combustion flame in the premixing chamber 41, and when the optical power is equal to or higher than the set value, an abnormal alarm is issued. Fired, the ignition plug 51 is ignited, the flow rate of the fuel sprayed from the second fuel injection valve 46 to the auxiliary combustion chamber 44 is slightly increased, and the flow rate of the fuel sprayed from the first fuel injection valve 45 to the premixing chamber 41 is set to the first level. 2 The fuel flow rate of the fuel injection valve 46 is decreased by the increase.

As long as the flow rate of the fuel sprayed into the premix chamber 41 does not become zero and the light power of the combustion flame in the premix chamber 41 is equal to or more than the set value, it is sprayed into the auxiliary combustion chamber 44 as described above. Generated in the premixing chamber 41 after repeatedly increasing the fuel flow rate and decreasing the fuel flow rate sprayed in the premixing chamber 41 to keep the total flow rate of the fuel flow sprayed in the auxiliary combustion chamber 44 and the premixing chamber 41 constant. Extinguish the burning flame.

Even if the flow rate of the fuel sprayed into the premix chamber 41 becomes zero, if the optical power of the combustion flame in the premix chamber 41 is equal to or more than the set value, the fuel is supplied to all the fuel injection valves 45 and 46. Stop and issue an abnormal alarm.

When the combustion flame generated in the premix chamber 41 is extinguished, conversely, the flow rate of fuel sprayed in the auxiliary combustion chamber 44 is decreased and the flow rate of fuel sprayed in the premix chamber 41 is increased.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a premixed combustion device that implements a control method according to a first example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the air flow rate adjusting mechanism of the premixed combustion device, which is a cross-sectional view taken along the line AA of FIG.

3 is a cross-sectional view of the air swirl adjusting mechanism of the premixed combustion device, which is a cross-sectional view taken along the line AA of FIG. 1. FIG.

FIG. 4 is a vertical cross-sectional view of a second flame detection device incorporated in a second fuel injection valve of the premixed combustion device.

FIG. 5 is a diagram of a power spectrum of combustion flame light of a combustion chamber in the premixed combustion device.

FIG. 6 is a view showing a relationship between a power spectrum ratio of a combustion chamber and an average excess air ratio in the premixed combustion device.

FIG. 7 is a flow chart of a method of controlling combustion in a combustion chamber based on an average excess air ratio when the operating conditions have small fluctuations in the premixed combustion apparatus.

FIG. 8 is a flowchart of a method for controlling combustion in a combustion chamber based on an average excess air ratio when the operating conditions vary greatly in the premixed combustion apparatus.

FIG. 9 is a flowchart of a method for controlling combustion in a combustion chamber based on a combustion temperature in the premixed combustion device.

FIG. 10 is a flowchart of a method for controlling abnormal combustion in the premix chamber in the premix combustion apparatus.

FIG. 11 is a vertical cross-sectional view of a premixed combustion device that implements the control method of the second example of the embodiment.

FIG. 12 is a sectional view of a flame detection device position of the premixed combustion device.

FIG. 13 is a vertical cross-sectional view of a premixed combustion device that implements the control method of the third example of the embodiment.

FIG. 14 is a sectional view of a flame detection device position of the premixed combustion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Premixing chamber 2 Combustion chamber 3 Dilution mixing chamber 4 1st fuel injection valve 5 2nd fuel injection valve 6 Air passage 7-12 Air flow rate adjusting mechanism 7,13-19 Air swirling adjusting mechanism 20,21 1st flame detection apparatus 23, 26 2nd flame detection device 31 premixing chamber 32 main combustion chamber 33 dilution mixing chamber 34 auxiliary combustion chamber 35 first fuel injection valve 36 second fuel injection valve 37 air passage 38, 39 flame detection device 41 premixing chamber 42 Main combustion chamber 43 Dilution mixing chamber 44 Sub-combustion chamber 45 First fuel injection valve 46 Second fuel injection valve 47 Air passage 49, 50 Flame detection device

Claims (6)

[Claims] 1. A premixing chamber for mixing fuel and air, a combustion chamber for burning a mixture of fuel and air, and a dilution mixing chamber for mixing combustion gas and air are sequentially connected, and fuel is sprayed into the premixing chamber. In the premixed combustion device, a first fuel injection valve for controlling the premixing chamber and a second fuel injection valve for spraying fuel into the combustion chamber are provided, and an air passage for supplying air to the premixing chamber and the dilution mixing chamber or the combustion chamber is provided. When the combustion that occurs in the mixing chamber is detected, the flow rate of the fuel sprayed into the premixing chamber is decreased, or the flow rate of the air supplied to the premixing chamber is increased, or the flow rate of the fuel sprayed into the premixing chamber is increased. A control method characterized by increasing the flow rate of air supplied to the premixing chamber to decrease the combustion flame in the premixing chamber while decreasing the flow rate. 2. The control method according to claim 1, wherein when the flow rate of the fuel sprayed into the premixing chamber is decreased, the flow rate of the fuel sprayed into the combustion chamber is increased by the decrease amount. Method. 3. A premixing chamber that mixes fuel and air, a combustion chamber that burns a mixture of fuel and air, and a dilution mixing chamber that mixes combustion gas and air are sequentially connected, and fuel is sprayed into the premixing chamber. In the premixed combustion device, a first fuel injection valve for controlling the fuel injection and a second fuel injection valve for spraying fuel into the combustion chamber are provided, and an air passage for supplying air to the premixing chamber and the dilution mixing chamber or the combustion chamber is provided. By detecting the state quantity of combustion flame in the chamber, or by the flow rate of fuel supplied to both fuel injection valves, the flow rate of air supplied to the air passage, the air pressure at the air passage inlet, the combustion gas pressure at the dilution mixing chamber outlet Detecting the air temperature at the inlet of the air passage to find the average excess air ratio in the combustion chamber.When the average excess air ratio is smaller than the lower limit of the desired range, increase the flow rate of the air supplied to the premix chamber to obtain the average value. Excess air ratio is greater than the upper limit of the desired range Kiniwa, decreases the flow rate of air supplied to the premixing chamber, a control method, characterized by the average air excess ratio in the combustion chamber within a desired range. 4. A premixing chamber that mixes fuel and air, a combustion chamber that burns a mixture of fuel and air, and a dilution mixing chamber that mixes combustion gas and air are sequentially connected, and fuel is sprayed into the premixing chamber. In the premixed combustion device, a first fuel injection valve for controlling the fuel injection and a second fuel injection valve for spraying fuel into the combustion chamber are provided, and an air passage for supplying air to the premixing chamber and the dilution mixing chamber or the combustion chamber is provided. The average amount of excess air in the combustion chamber is determined by detecting the state quantity of the combustion flame in the chamber, and the flow rate of the air supplied to the air passage, the air pressure at the air passage inlet, the combustion gas pressure at the dilution mixing chamber outlet, and the air passage inlet Detect the air temperature to find the combustion temperature in the combustion chamber.If the combustion temperature is lower than the lower limit of the desired range, reduce the flow rate of the air supplied to the premix chamber and increase the combustion temperature to the upper limit of the desired range. When larger, air supplied to the premix chamber Control method characterized by increasing the flow rate, the combustion temperature in the combustion chamber within a desired range. 5. The control method according to claim 3, wherein when the combustion generated in the premix chamber is detected, the flow rate of the fuel sprayed into the premix chamber is reduced or the air supplied to the premix chamber is supplied. Is increased or the flow rate of the fuel sprayed into the premix chamber is decreased, and the flow rate of the air supplied to the premix chamber is increased to extinguish the combustion flame in the premix chamber. Control method. 6. The control method according to claim 1, wherein when the flow rate of the air supplied to the premixing chamber is increased, the swirl number of the swirling flow of the air is reduced so that A control method characterized by increasing the swirl number of the swirling flow of the air when decreasing the flow rate of the supplied air.