JPH10311229A - Gas turbine plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve ignition reliability of a gas turbine combustor, perform stable combustion, further reduce an amount of NOx emission of a dry type liquid low NOx combustor to reduce an amount of NOx generation, and provide an eminently increased life for a combustor liner through suppression of combustion vibration in the combustor. SOLUTION: A gas turbine 31, a turbine compressor 32, and a generator 33 are intercoupled through a turbine shaft 34. An air feed system 40 is provided to feed air to atomize liquid fuel to a combustor 36. The air feed system 40 is provided with a compressor 41 for atomizing liquid fuel having a shaft different from a turbine shaft 34. The compressor 41 for atomizing liquid fuel is coupled to a motor 42, serving as a drive machine, through a boosting gear 43. The motor 42 forms a number of revolution variable type and the number of revolutions is controlled through a motor control system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine plant using a liquid fuel as a power source, and more particularly to a gas turbine plant capable of effectively stabilizing a combustion flame and reducing the concentration of exhaust NOx.

[0002]

2. Description of the Related Art Conventionally, gaseous fuels such as liquefied natural gas are often used as fuels in gas turbine plants for power generation. However, diversification has been demanded from the viewpoint of stable fuel supply, and in recent years, in addition to gaseous fuels, Technology development for applying liquid fuels such as petroleum fuels and alcohol fuels has been advanced.

[0003] Recently, a combined power plant combining a gas turbine and a steam turbine has attracted attention from the viewpoint of improving efficiency, and has become a state occupying the mainstream of the power plant. Also, it has been demanded to use a plurality of fuels in which a gaseous fuel and a liquid fuel are combined.

[0004] When a liquid fuel is burned in a combustor of a gas turbine, it is generally supplied in a spray state by mixing with air. However, particles of the liquid fuel to be sprayed are gas such as liquefied natural gas. The fuel nozzle of the combustor of a normal gas turbine, which has been developed mainly for the combustion of liquefied natural gas, is not necessarily suitable for supplying liquid fuel because it is larger than the fuel.

[0005] From this, research on a fuel nozzle suitable for liquid fuel supply has been advanced, and high-speed air (atomized air) for atomizing fuel is blown from the nozzle tip around the liquid fuel to atomize the liquid fuel. A fuel nozzle having a configuration is proposed, and a technique for adding a liquid fuel atomizing air supply system for atomizing liquid fuel by atomizing air is proposed.

FIG. 7 is a system diagram showing a gas turbine plant for liquid fuel developed so far. In this plant, a gas turbine 1, a turbine compressor 2 and a generator 3 are connected by a turbine shaft 4. And
In a normal combustion air supply system, combustion air (atmosphere) a
Is introduced into the turbine compressor 2 through the duct 5, and the air pressurized by the turbine compressor 2 is supplied to the fuel nozzle 7 of the combustor 6 to burn the liquid fuel b supplied from the fuel pipe 8. It has become. The high-temperature combustion gas generated in the combustor 6 flows into the gas turbine 1 to drive the turbine, and then is discharged through the exhaust tower 9. Power generated by the gas turbine 1 is power for driving the turbine compressor 2 and the generator 3 connected to the turbine shaft 4.

In such a configuration, an air supply system 10 for atomizing liquid fuel which supplies air for atomizing liquid fuel is provided. The air supply system 10 for atomizing liquid fuel is provided with a gear mechanism 1 for speed increase on the turbine shaft 4.
1, a liquid fuel atomization compressor 12 connected via
It has an auxiliary atomizing compressor 13 that is separate from the turbine shaft 4.

[0008] The fuel atomizing compressor 12 is used during normal operation. High-pressure discharge air from the turbine compressor 2 is taken in through a connecting pipe 14, and is further pressurized to form an air supply pipe 15 as atomized air. The fuel is supplied to the fuel nozzle 7 of the combustor 6 via the fuel nozzle 7. This atomized air is blown out from the tip of the fuel nozzle 7 around the liquid fuel at a high speed so that the liquid fuel is in a fine spray state. The connection pipe 14 is provided with a heat exchanger 16 for cooling air discharged from the turbine compressor 2 and a check valve 17 for preventing backflow. Air supply pipe 1
5 is provided with an orifice 18 for preventing overflow. In the fuel atomization compressor 12, since the turbine shaft 4 is used as a driving source, a stable compression action is performed at a constant speed when the turbine shaft 4 is rotating stably, but the rotation of the turbine shaft 4 is unstable. , The compression action becomes unstable.

On the other hand, the auxiliary atomizing compressor 13 is used during the speed-up period until the turbine shaft 4 rotates at a sufficiently high speed, such as when the gas turbine is started.
With this, it is driven to rotate at a constant speed.
The discharge port side of the auxiliary atomizing compressor 13 is connected to a check valve 20.
Atomizing compressor 12 by an auxiliary pipe 21 having
The air c, which is connected to the suction port side, is compressed into atomized air by taking in the air c from the outside, and the air c is supplied to the combustor 6 through the auxiliary pipe 21, the fuel atomizing compressor 12, and the air supply pipe 15.
To the fuel nozzle 7.

The fuel nozzle 7 provided in the combustor
Consists of a pilot fuel nozzle provided at the head of the combustion chamber, and a number of main fuel nozzles for blowing lean fuel into a premixing duct arranged around the pilot fuel nozzle. The pilot fuel nozzle is used for the normal operation, and the main fuel nozzle is mainly used during the steady operation. That is, the gas turbine is accelerated by the combustion gas of the fuel injected from the pilot fuel nozzle until the number of revolutions of the generator reaches the rated operation, and then the temperature inside the liner of the combustor 6 rises and premixed combustion is performed. When it becomes possible, the second stage fuel is injected into the main fuel nozzle.

[0011]

In recent years, it has been required to reduce nitrogen oxides (NOx) in gas turbine exhaust gas from the viewpoint of environmental protection. In response to this, natural gas combustion type gas turbines have low NOx. Along with the development of combustors, the reduction of NOx in gas turbines for liquid fuel combustion has also been promoted, and an efficient dry low NOx
Combustors are being developed.

In such a dry low NOx combustor, N
In order to reduce Ox, a premixed lean combustion system using a main fuel nozzle and a premixing duct is employed up to nearly 80% of the total, but in this combustion system, the flame in the combustor tends to be unstable. Therefore, if the atomizing air for atomizing the fuel is not controlled to an appropriate value, flame loss (misfire) occurs, which may cause a serious problem that power generation is stopped.

On the other hand, when liquid fuel is used, NOx
In order to reduce fuel consumption, a large amount of atomized air must be supplied because the fuel needs to be atomized and vaporized in the premixing duct and mixed uniformly. FIG. 8 shows the relationship between the NOx emission characteristics and the spray particle diameter of the fuel during combustion in the premixing duct, that is, during the second-stage combustion with the above-described second-stage fuel injection. As shown by the characteristic line A in the figure, it is understood that atomization of the fuel is necessary to improve the NOx reduction characteristics. This atomization of fuel requires a large amount of atomized air.

As described above, in the main fuel nozzle using the liquid fuel, it is necessary to control the atomized air to an appropriate value in order to stabilize the flame in the combustor. The need to supply atomized air to atomize fuel must meet the conflicting demands from both sides.

[0015] Similar conflicting demands also appear when looking at the relationship between the main fuel nozzle and the pilot fuel nozzle. That is, since the temperature of the combustion air is high at the outlet of the turbine compressor 2, when the high-temperature air and the liquid fuel are mixed, spontaneous ignition occurs when a certain time has elapsed due to heating of the fuel. When spontaneous ignition occurs, there arises a problem that components of the combustor 6 are melted and turbine components on the downstream side are damaged. Therefore, from the viewpoint of preventing such spontaneous firing, the premixing section provided with the main fuel nozzle has a limit in the fuel residence time, and the premixing duct cannot be lengthened unnecessarily. In other words, in order to vaporize the liquid fuel in a short time in the premixing duct and achieve a uniform mixing state, atomization of the fuel spray is strongly required, and therefore, a large amount of atomized air must flow into the main fuel nozzle. There is.

FIG. 9 shows the relationship between the supply amount of the atomized air and the spray particle size of the liquid fuel. From the characteristic line B shown in the figure, it is understood that it is necessary to increase the supply amount of atomized air in order to reduce the spray particle diameter of the liquid fuel.

On the other hand, in the case of the pilot fuel nozzle, the fuel supply rate must be increased in order to stabilize the flame in the speed-up region up to the vicinity of the rated speed of the gas turbine after ignition of the fuel. FIG. 10 shows the relationship between the fuel / combustion air ratio (F / A ratio) and the gas turbine speed (%) from the time after ignition operating with the pilot fuel nozzle to the vicinity of the gas turbine rated speed. is there. That is, in a gas turbine, a plurality of combustors are provided, and at the time of ignition, two electric combustors are usually ignited by flying electric sparks, and the other combustors are ignited through a flame propagation tube. When propagating this flame, the flame temperature is low at the normal ignition F / A ratio,
Since the adjacent combustor is not sufficiently fired, a large amount of fuel is temporarily supplied to stabilize the flame in order to actually perform sufficient flame propagation. Then, after confirming that all the combustors have fired, the fuel is narrowed down and the warm-up operation is performed to protect the gas turbine high-temperature equipment. After performing the warm-up operation for a while, the operation shifts to the acceleration operation toward the rated rotation speed. In the vicinity of the end of the acceleration operation, the compressed air temperature at the compressor outlet, that is, at the inlet of the combustor, increases with the rotation speed of the gas turbine. Therefore, when the operation is performed at the same F / A ratio as before, the rotation speed increases greatly. Since it becomes too much, it is necessary to gradually narrow down the fuel so as not to overspeed.

In FIG. 10, a characteristic line C of a normal F / A ratio is indicated by a solid line, and a characteristic line D at an unstable time is indicated by a broken line. When the F / A ratio drops from the characteristic line C during normal operation, the combustion temperature decreases, and when the state shown by the characteristic line D is reached, the flame of the pilot combustion section becomes unstable. Flame blows out (misfire).

As described above, when a large amount of atomized air is supplied to the center of the pilot fuel nozzle that holds the combustion flame from ignition to low NOx combustion to reduce NOx, the temperature decreases and the local flow velocity increases. And the flame becomes unstable during acceleration, and sometimes misfire may occur.

Under the circumstances described above, conventionally, as described above, the atomized air is always supplied at a fixed flow rate, and the atomized air is not always appropriately controlled to reduce NOx and stabilize the flame. Not.

The present invention has been made in view of such circumstances, and a purpose thereof is to provide a gas turbine plant using a liquid fuel, which can appropriately control atomized air, and thereby, from the time of ignition. An object of the present invention is to make it possible to perform stable operation without fear of misfiring or the like over the entire operation period up to steady-state rotation, and to enable sufficient atomization of fuel to reduce NOx.

Further, the present invention simultaneously enhances the life of the combustor liner by suppressing combustion oscillation in the combustor, and reduces the thermal stress at the time of ignition of the high-temperature equipment of the gas turbine. It is intended to prevent the occurrence of cracks on the surface which are likely to occur, to prolong the time interval of maintenance, to reduce the maintenance and inspection costs, and the like.

[0023]

In order to achieve the above object, according to the first aspect of the present invention, liquid fuel is atomized by mixing with air, and the atomized liquid fuel is blown into a combustor for combustion. A gas turbine plant for driving a gas turbine with the combustion gas, wherein the atomizing air is supplied to a fuel nozzle tip of the combustor as a high-speed flow pressurized by a liquid fuel atomizing compressor. , Wherein the liquid fuel atomizing compressor is driven by a motor, and the motor has a variable number of revolutions.

According to a second aspect of the present invention, in the gas turbine plant according to the first aspect, the fuel nozzle supplies lean fuel to a pilot fuel nozzle provided at the head of the combustion chamber and a premixing duct disposed therearound. These fuel nozzles are the main fuel nozzles to be blown in. These fuel nozzles are a fuel spray nozzle of a pressure spray type that continuously jets a pressurized liquid fuel, and a fuel atomizer for atomizing the liquid fuel from around the fuel jet nozzle. A gas turbine plant having an air supply nozzle for atomizing fuel for blowing and mixing air.

According to a third aspect of the present invention, in the gas turbine plant according to the first aspect, the rotation speed of the liquid fuel atomization compressor is controlled based on the rotation speed of the turbine shaft. Provide a gas turbine plant.

According to a fourth aspect of the present invention, in the gas turbine plant according to the first aspect, the rotation speed of the liquid fuel atomization compressor is controlled based on the plant output. I will provide a.

According to a fifth aspect of the present invention, in the gas turbine plant of the first aspect, a configuration is provided in which the rotation speed of the compressor for atomizing the liquid fuel is controlled based on both the rotation speed of the turbine shaft and the plant output. There is provided a gas turbine plant characterized by the above.

According to a sixth aspect of the present invention, in the gas turbine plant according to the first aspect, the number of revolutions of the compressor for atomizing the liquid fuel is controlled based on combustion vibration in the combustor. To provide a gas turbine plant.

According to a seventh aspect of the present invention, in the gas turbine plant according to the first aspect, the rotational speed of the compressor for atomizing the liquid fuel is determined based on both factors of the combustion vibration in the combustor and the rotational speed of the turbine shaft. Provided is a gas turbine plant having a control structure.

According to an eighth aspect of the present invention, in the gas turbine plant according to the first aspect, the rotational speed of the compressor for atomizing the liquid fuel is controlled based on both factors of the combustion oscillation in the combustor and the plant output. A gas turbine plant is provided.

According to a ninth aspect of the present invention, in the gas turbine plant according to the first aspect, the number of revolutions of the compressor for atomizing the liquid fuel is determined by the three factors of combustion oscillation in the combustor, the number of revolutions of the turbine shaft, and the plant output. A gas turbine plant characterized in that the control is performed based on the following.

According to a tenth aspect, in the gas turbine plant according to any one of the first to ninth aspects,
Provided is a gas turbine plant wherein a liquid fuel atomizing compressor and a fuel nozzle of a combustor are connected by an atomizing air supply pipe, and a flow rate adjusting orifice is provided at an intermediate portion of the pipe.

According to the eleventh aspect of the present invention, in the gas turbine plant according to the tenth aspect, the atomizing air supply pipe for connecting the liquid fuel atomizing compressor and the fuel nozzle of the combustor includes the pilot fuel nozzle and the main fuel nozzle. A gas turbine plant is provided in which a plurality of fuel nozzles are provided corresponding to fuel nozzles.

According to a twelfth aspect of the present invention, in the gas turbine plant according to the eleventh aspect, the atomizing air supply pipe connecting the liquid fuel atomizing compressor and the fuel nozzle of the combustor includes a pilot fuel nozzle and a main fuel nozzle. A gas turbine plant is provided, wherein a plurality of nozzles are provided corresponding to the nozzles, and a flow adjusting orifice is provided in each of the atomizing air supply pipes.

According to the thirteenth aspect, in the tenth aspect,
2. In the gas turbine plant according to any one of (2) to (2), the air discharged from the liquid fuel atomizing compressor is branched from the atomizing air supply pipe and returned to the suction side of the liquid fuel atomizing compressor. A gas turbine plant is provided, wherein an air return pipe is provided, and a flow control valve is provided at an intermediate portion of the air return pipe for atomization.

According to a fourteenth aspect of the present invention, there is provided a gas turbine plant in which liquid fuel is atomized by mixing with air, and the atomized liquid fuel is blown into a combustor to be burned, and the combustion gas drives a gas turbine. Supplying the air for atomization as a high-speed flow compressed by a compressor for atomizing liquid fuel to the tip of a fuel nozzle of the combustor; The compressor for driving the gasification is driven by a turbine shaft, and when the rotation speed of the gas turbine is low, the compressor is driven by a separate motor-driven auxiliary compressor, and the flow rate adjusting device according to any one of claims 10 to 12 An atomizing air supply pipe with an orifice;
A gas turbine plant provided with the atomizing air return pipe with the flow control valve described above.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gas turbine plant according to the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram showing a configuration of a gas turbine plant according to one embodiment of the present invention. In the present embodiment, the gas turbine 31, the turbine compressor 32, and the generator 33 are connected by a turbine shaft 34. Then, in a normal combustion air supply system, combustion air (atmosphere) a is introduced into the turbine compressor 32 via a duct 35, and the air compressed by the turbine compressor 32 is
The liquid fuel b supplied from the fuel pipe 38 is supplied to the fuel nozzle 37 of No. 6 to burn the liquid fuel b. The high-temperature combustion gas generated in the combustor 36 flows into the gas turbine 31 to drive the turbine, and then is discharged through the exhaust tower 39. The power generated by the gas turbine 31 is supplied to a turbine compressor 32 connected to a turbine shaft 34 and a power generator 3.
3 is the driving power.

In such a configuration, in the present embodiment, the liquid fuel atomizing air supply system 40 for supplying air for atomizing the liquid fuel is provided with a liquid fuel atomizing air supply system separate from the turbine shaft 34. The configuration includes a compressor 41.

That is, the liquid fuel atomizing compressor 41
Is connected via a speed increasing gear 43 to a motor 42 as a driving machine. The motor 42 is of a variable rotation speed type, and is controlled in rotation speed by a motor control system described later.

The compressor 41 for atomizing liquid fuel takes in high-pressure discharge air from the turbine compressor 32 via a connecting pipe 44, and takes in the connecting pipe 44 from the turbine compressor 32. A heat exchanger 45 for cooling the air is provided. As the heat exchanger 45, for example, a type that circulates the cooling water d is applied, and the temperature of the air in the connecting pipe 44 is detected by the temperature sensor 46 to control the opening of the flow control valve 48 of the cooling water pipe 47. It has become.

An air supply pipe 49 for atomization is provided at the outlet side of the compressor 41 for atomizing liquid fuel. , Ie, a pilot fuel nozzle and a main fuel nozzle described later. As a result, the air pressurized by the liquid fuel atomization compressor 41 is supplied to the fuel nozzle of the combustor 36 as atomized air, and is blown from the tip of the fuel nozzle around the liquid fuel b at a high speed to discharge the liquid fuel b. Fine spray state.
The atomizing air supply pipe 49 is provided with a check valve 50 for preventing backflow and an orifice 51 for adjusting flow rate.

Here, a motor control system 52 for controlling the motor 42 for driving the compressor 41 for atomizing the liquid fuel.
Will be described. The motor control system 52 controls the rotation speed of the liquid fuel atomization compressor 41 (the rotation speed of the motor 42).
Is controlled on the basis of three factors: combustion vibration in the combustor 36, the rotation speed of the turbine shaft 34, and the plant output.

That is, a vibration detection sensor 53 is provided in the combustor 36, and detects a vibration generated in the combustor 36 due to a change in the combustion state and generates a vibration signal S1. The turbine shaft 34 is provided with a rotation speed detection sensor 54, which detects a change in the rotation speed of the turbine shaft during operation and generates a rotation speed signal S2. Further, a generator output converter 55 is connected to the generator 33 to emit a plant output signal S3. Signals S1, S2 and S2 emitted from these sensors 53, 54 and 55, respectively.
S3 is input to the arithmetic unit 56, and based on this, the arithmetic unit 56 performs a control operation, and the result is output as an arithmetic signal S4
Is output to the rotation speed control device 57. Then, in the rotation speed control device 57, a rotation speed control signal S5 according to the operating state from each of the sensors 53, 54, 55 is output to the motor 42, and the rotation speed of the motor 43 and, consequently, the rotation of the compressor 41 for atomizing the liquid fuel. The number is controlled, and the supply amount of the atomized air to the combustor 36 is controlled.

Next, an example of the structure of the combustor (low NOx combustor for liquid fuel) 36 and the fuel nozzle provided therein will be described with reference to FIGS. FIG. 2 shows a schematic configuration of the combustor 36 and a fuel nozzle (pilot fuel nozzle 5).
FIG. 8 is a cross-sectional view showing an arrangement configuration and the like of a main fuel nozzle 59). FIG. 3 is a configuration diagram in which the pilot fuel nozzle 58 is enlarged and a part is shown in cross section, and FIG. 4 is a configuration diagram in which the main fuel nozzle 59 is enlarged and shown in cross section.

As shown in FIG. 2, the combustor 36 has a cylindrical shape as a whole, and a flow sleeve 61 for guiding combustion air is provided on the inner peripheral side of an outer peripheral wall 60 constituting an outer shell. Liner 6 as a combustor body on the inner peripheral side
2 are arranged, and the inside of the liner 62 is a combustion chamber 63. A pilot fuel nozzle 58 is provided at the center position of the head of the combustor 36, and a main fuel nozzle 59 is provided on the head side of a plurality of premixing ducts 64 formed of manifolds provided so as to surround the pilot fuel nozzle. Is provided.

The combustion air supplied from the turbine compressor flows inside the flow sleeve 61 toward the head side as shown by an arrow e in FIG. The air is blown into the combustion chamber 63 from the swirler 65 to be used for pilot combustion, and is also blown into the head side of the premixing duct 64 to be used for main combustion.

As shown in FIG. 3, the pilot fuel nozzle 58 is of a type for selectively burning gas fuel f and liquid fuel b, for example.
6, a triple passage configuration having an atomizing air passage 67 around the periphery and a gas fuel passage 68 around the periphery. The liquid fuel b is agitated by the passage change while passing through the liquid fuel passage 66 in the center, is blown out from the nozzle tip, and is atomized by atomizing air g ejected from around the nozzle tip. is there. When gas fuel is used, the outermost gas fuel passage 66 is used.
From the fuel gas f blows out to the swirler 65 and the combustion air e
Mixed with.

As shown in FIG. 4, the main fuel nozzle 59 is of a type for injecting the liquid fuel b exclusively, and has a liquid fuel passage 69 at the center and an atomizing air passage 70 around the double passage. It has a passage configuration. The liquid fuel b is blown out from the nozzle tip by obtaining the stirring action by the passage change while passing through the liquid fuel passage 69 at the center, and is atomized by the atomized air g ejected from around the nozzle tip. is there.

Next, the operation will be described.

During operation, first, the turbine shaft 34 is rotated by a starting motor (not shown), and the rotation speed of the gas turbine 31 reaches a predetermined rotation speed.
The air purge operation is performed by the turbine compressor 32 so that the combustible air-fuel mixture does not exist in the exhaust duct including the air compressor.

After the air purge is completed and the rotation speed of the gas turbine 31 is set to the ignition rotation speed, the liquid fuel b is atomized with atomized air while discharging by the spark plug in the combustor 36, and The fuel is blown into the pilot fuel nozzle 58 to ignite. When the ignition of all of the plurality of combustors 36 is completed, a method of narrowing down the fuel in order to protect each device in the high temperature portion of the gas turbine, reducing the unsteady thermal stress at the time of ignition, and extending the life of the device is adopted.

In the warm-up operation after ignition, if the flow rate of the atomized air is extremely large, as shown in FIG. 10 described above, the operation is performed in a region near the limit of the blow-out of the pilot flame. Further, at this rotation speed, the turbine compressor 32
Since the outlet temperature is close to room temperature, it is easy to misfire. Therefore, in the warm-up operation, at the stage where the ignition and the transfer of the fire in the combustor 36 are completed and the fuel is narrowed down, the rotation speed of the liquid fuel atomization compressor 41 is reduced by a command from the rotation speed control device 57 and the atomization is performed. Reduce the air supply.

In this embodiment, as the control elements of the rotation speed control device 57, the vibration signal S1 of the combustor 36 from the vibration detection sensor 53, the rotation speed rotation signal S2 of the turbine shaft 34 from the rotation speed detection sensor 54, And the plant output signal S3 from the generator output converter 55 is used. Based on these signals S1, S2, and S3, the arithmetic unit 56 and the rotation speed control unit 57 vibrate due to unstable combustion during warm-up operation, Speed control signal S5 according to the low output, etc.
Is output to the motor 42. Then, the rotation speed of the liquid fuel atomization compressor 41 is reduced, and the supply amount of the atomized air to the combustor 36 is reduced. Thereby, combustion can be stabilized.

After the warm-up operation, the operation shifts to the acceleration operation for the rated operation. In this case, even during the speed increase from the ignition of the gas turbine to the vicinity of the rated operation, combustion is performed by using the pilot fuel nozzle alone, and the flame in the combustion region is unstable due to the low temperature in the combustor. It is in.
If the ratio of the atomized air to the fuel flow rate is increased in such an operating state and a large amount is supplied as in premixed combustion, the speed of injection into the combustor is too high to keep up with the combustion speed, resulting in unstable combustion and flame. Blow off occurs.
Therefore, also at this stage, the rotation speed of the liquid atomizing compressor 41 is reduced, and the atomized air flow rate is reduced. As a result, the pilot flame temperature can be increased, and the circulation speed of the flame holding region at the center of the pilot flame can be reduced. Therefore, gas turbine trip due to unstable combustion, combustion vibration, or pilot flame blow-off (misfire) can be prevented. Can be prevented.

This operation will be described in detail with reference to FIG. 10 described above.
00%), the ratio of liquid fuel to air in the combustor (F /
In contrast, in the prior art, the rotational speed of the liquid atomizing compressor 41 was fixed and the atomized air flow rate was constant. I was And as you can see from this graph,
The region where the F / A ratio indicated by the solid line C approaches the broken line D, which is the misfire line, is the latter half of the warm-up operation and the acceleration operation, and combustion in this portion was particularly unstable. On the other hand, in the present embodiment, the supply air amount itself can be reduced by controlling the rotation speed of the compressed air 41 for atomizing the liquid fuel to decrease the flow rate of the atomized air in this portion. , The misfire range can be reduced to the line indicated by the broken line E in FIG. Therefore, when the operation is performed along the solid line C, it is possible to perform an operation that is sufficiently separated from the broken line E, which is the misfire line, to improve the unstable range of the flame, and to ensure the prevention of misfire.

At the end of the acceleration operation, the temperature of the compressed air at the outlet of the turbine compressor 32, that is, at the inlet of the combustor 36, increases with the rotation speed of the gas turbine. When driving, the increase in the number of revolutions becomes too large. Therefore, the fuel is gradually reduced so as not to cause overspeed.

Thereafter, when the second stage fuel is supplied, combustion is performed using the main fuel nozzle, and the rated operation is performed. In this case, as described above, the generation of NOx has been a problem, but in the present embodiment, this NOx generation amount can be reduced by increasing the supply amount of the atomized air.

That is, the vibration of the combustor 36 becomes small because the combustion is stable during the rated operation, and this is detected by the vibration signal S 1 from the vibration detection sensor 53. The high-speed rotation of the turbine shaft 34 is controlled by the rotation speed detection sensor 5.
4 is detected by the rotational speed signal S2 from the motor. Further, an increase in the plant output is detected by a plant output signal S3 from the generator output converter 55. In the present embodiment, based on these signals S1, S2, S3, the arithmetic unit 56 and the rotational speed control unit 57 control the rotational speed control signal S5 corresponding to low vibration, high rotational speed, high output, etc. due to stable combustion during steady operation. Is output to the motor 42. And
The rotation speed of the liquid fuel atomization compressor 41 is increased, and the supply amount of the atomized air to the combustor 36 is increased. The operation of the atomized air will be described below.

That is, FIG. 5 shows the relationship between the pressure ratio and the rotation speed in the compressor 41 for atomizing liquid fuel. As can be seen from the characteristic line F shown in FIG. 5, the pressure ratio (P2 / P1) obtained by dividing the compressed air outlet pressure (P2) by the compressed air inlet pressure (P1) with an increase in the compressor rotation speed.
Rises at an accelerated rate. On the other hand, as shown by the characteristic line B in FIG. 9 described above, with respect to the atomization characteristics of the air atomization type liquid fuel nozzle, the spray particle diameter of the liquid fuel decreases at an accelerated rate due to an increase in atomized air. This means that if the premixing and pre-evaporation of the fuel is performed in a short time by increasing the rotation speed of the liquid fuel atomizing compressor 41 and supplying a large amount of atomized air, a uniform lean premixed gas can be produced. This means that NOx generated in the combustor can be significantly reduced. In the present embodiment, since the rotation speed of the liquid fuel atomization compressor 41 is variable and can be set to a required rotation speed, the liquid fuel atomization compressor 41 in the premixed combustion state. A large amount of atomized air is flowed into the premixed fuel by increasing the rotation speed of the premixed fuel, and atomization of the fuel can be achieved. Therefore, the premixing pre-evaporation of the fuel can be performed in a short time, and a uniform lean premixed gas can be produced in the length range of the premixing nozzle 64 equal to or less than a certain value.
NOx generated in the combustor can be significantly reduced.

Further, according to this embodiment, since the evaporation of the fuel droplets can be completed in a short time, a uniform premixed gas can be produced, thereby preventing spontaneous ignition and flashback in the premixing section. And a highly reliable dry low-NOx liquid combustor can be constructed. Further, in a gas turbine of a spark ignition type using an electric spark, the ignition probability of the gas turbine increases when the liquid fuel is atomized,
It is also possible to increase the reliability of the power generation operation.

Further, according to the present embodiment, since the compressor 41 for atomizing liquid fuel is independent of the turbine shaft 34, the compressor for auxiliary atomization which is conventionally provided for use at the time of startup is unnecessary. Becomes Therefore, the number of devices to be subjected to maintenance and inspection can be reduced, and the cost for periodic inspection and the inspection period can be reduced. Further, since the liquid fuel atomizing compressor 41 can be installed at a distance from the turbine shaft 34, the disassembly and inspection can be facilitated, thereby also shortening the inspection period.

As described above, according to this embodiment, the ignition reliability of the gas turbine combustor can be improved, and stable combustion can be performed.
It is possible to further reduce the amount of NOx emission in the dry liquid low NOx combustor in which the amount of generated x is reduced. Also,
The life of the combustor liner can be significantly improved by suppressing combustion oscillations in the combustor.Furthermore, by reducing the thermal stress at the time of ignition of high-temperature components of the gas turbine, the surface The occurrence of cracks can be prevented, the time interval of maintenance can be extended, and the maintenance and inspection costs can be reduced.

It should be noted that the present invention is not limited to the configuration shown in the above embodiment, and various applications or modifications are possible. For example, in a configuration using a conventional liquid fuel atomizing compressor and an auxiliary atomizing compressor to adjust the flow rate of atomized air, the atomizing air is moved from the discharge side to the suction side of the liquid fuel atomizing compressor. May be provided, and a flow control valve for adjusting the return amount may be provided.

FIG. 6 shows an embodiment having such a return path for the atomized air. In this embodiment, a gas turbine 31, a turbine compressor 32 and a generator 33 are connected by a turbine shaft 34. Then, in a normal combustion air supply system, combustion air (atmosphere) a is introduced into the turbine compressor 32 via a duct 35, and the air compressed by the turbine compressor 32 is
The liquid fuel b supplied from the fuel pipe 38 is supplied to the fuel nozzle 37 of No. 6 to burn the liquid fuel b.

On the other hand, similar to the conventional one shown in FIG.
Liquid fuel atomizing compressor 72 coaxial with turbine shaft 31
And a separately provided motor-driven auxiliary compressor 73. However, an atomizing air return pipe 75 which branches from the atomizing air supply pipe 74 and returns the discharge air of the liquid fuel atomizing compressor 72 to the suction side of the liquid fuel atomizing compressor 72 is provided. A flow control valve 76 is provided at an intermediate portion of the atomizing air return pipe 75. When the rotation speed of the gas turbine is high, the compressor 72 for atomizing liquid fuel is driven by the turbine shaft, and when the rotation speed of the gas turbine is low, the separately mounted motor-driven auxiliary compressor 7 is provided.
3 is driven. The atomizing air supply pipe 74 is divided into a plurality of sections, each of which is provided with a flow rate adjusting orifice 77. Since other piping configurations and the like are the same as those in FIG. 7, the same reference numerals are given to the drawings and description thereof will be omitted.

The flow control valve 76 is controlled by a valve control system 78. This control system also has the vibration detection sensor 53 of the combustor 36, as in the first embodiment.
The rotation speed detection sensor 54 of the turbine shaft 34, the generator output converter 55 of the generator 33, and the like are provided. Signals S1, S2, S3 emitted from these sensors 53, 54, 55
Is input to the arithmetic unit 56, and based on this, the arithmetic unit 5
In 6, a control calculation is performed, and the result is output to the valve control device 79 as a calculation signal S <b> 4. And each sensor 5
Valve control signal S6 according to the operation state from 3, 54, 55
5 is output to the flow control valve 76 and the flow rate to the atomizing air return pipe 75 is adjusted so that the amount of atomized air supplied by the atomizing air supply pipe 74 with the flow rate adjusting orifice 77 is controlled. It has become.

In the embodiment shown in FIG. 6 as well, the supply amount of the atomized air from the liquid fuel atomizing compressor 72 to the combustor 36 can be adjusted. The effect is achieved. In addition,
In this other embodiment, finer adjustments can be made by making the rotation speed of the liquid fuel atomization compressor 72 variable. Further, it can be used as an auxiliary mechanism when the rotation speed adjusting mechanism breaks down.

In the present invention, a transmission may be provided between the drive unit and the compressor impeller in order to make the rotation speed of the compressor for atomizing liquid fuel variable. is there.

Further, it is also possible to apply a valve mechanism instead of the orifice in each of the above embodiments, or to use an orifice and a valve mechanism together.

[0071]

As described above in detail, according to the present invention, the ignition reliability of the gas turbine combustor can be improved, stable combustion can be performed, and the amount of NOx generated can be reduced. Therefore, the NOx emission amount in the dry liquid low NOx combustor can be further reduced. In addition, the life of the combustor liner can be significantly improved by suppressing combustion oscillation in the combustor, and moreover, the thermal stress at the time of ignition of the high-temperature equipment of the gas turbine is reduced, so that the high-temperature parts are easily generated. It is possible to prevent the occurrence of cracks on the surface, increase the time interval for maintenance, and reduce the maintenance and inspection costs.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of an embodiment of a gas turbine plant according to the present invention.

FIG. 2 is a diagram showing a combustor structure in the embodiment.

FIG. 3 is an enlarged view showing a configuration of a pilot fuel nozzle in the embodiment.

FIG. 4 is an enlarged view showing a configuration of a main fuel nozzle in the embodiment.

FIG. 5 is a graph showing a relationship between a pressure ratio and a rotation speed in the compressor.

FIG. 6 is a system diagram showing a configuration of another embodiment of the gas turbine plant according to the present invention.

FIG. 7 is a system diagram showing a configuration of a conventional gas turbine plant.

FIG. 8 is a graph showing the relationship between the spray particle size of fuel and the amount of generated NOx.

FIG. 9 is a graph showing a relationship between a spray particle diameter of fuel and an atomized air flow rate.

FIG. 10 is a graph showing a relationship between an air-fuel ratio and a gas turbine speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Turbine compressor 3 Generator 4 Turbine shaft 5 Duct 6 Combustor 7 Fuel nozzle 8 Fuel pipe 9 Exhaust tower 10 Air supply system for atomizing liquid fuel 11 Gear mechanism 12 Compressor for atomizing liquid fuel 13 Auxiliary particles Compressor 14 Connecting pipe 15 Air supply pipe 16 Heat exchanger 17 Check valve 18 Orifice 19 Drive 20 Check valve 21 Auxiliary pipe 31 Gas turbine 32 Turbine compressor 33 Generator 34 Turbine shaft 35 Duct 36 Combustor 37 Fuel nozzle 38 Fuel pipe 39 Exhaust tower 40 Air supply system for liquid fuel atomization 41 Compressor for liquid fuel atomization 42 Motor 43 Speed-up gear 44 Connecting pipe 45 Heat exchanger 46 Temperature sensor 47 Cooling water pipe 48 Flow rate control valve 49 Fine particles Air supply piping 50 Check valve 51 Orifice 52 Motor control system 5 Vibration detection sensor 54 Rotation speed detection sensor 55 Generator output converter 56 Calculation device 57 Rotation speed control device 58 Pilot fuel nozzle 59 Main fuel nozzle 60 Outer peripheral wall 61 Flow sleeve 62 Liner 63 Combustion chamber 64 Premix duct 65 Swirler 66 Liquid fuel Passage 67 Atomized air passage 68 Gas fuel passage 69 Liquid fuel passage 70 Atomized air passage 72 Compressor for atomizing liquid fuel 73 Motor-driven auxiliary compressor 74 Air supply pipe for atomization 75 Air return pipe for atomization 76 Flow control valve 79 Valve control device 77 Flow control orifice a Combustion air (atmosphere) b Liquid fuel c Air d Cooling water f Gas fuel g Atomized air

Claims (14)

[Claims] 1. A gas turbine plant which atomizes liquid fuel by mixing with air, blows the atomized liquid fuel into a combustor and burns the fuel, and drives a gas turbine with the combustion gas. Supplying air to the fuel nozzle tip of the combustor as a high-speed stream pressurized by a liquid fuel atomization compressor,
A gas turbine plant, wherein the liquid fuel atomizing compressor is driven by a motor, and the motor has a variable rotation speed. 2. The gas turbine plant according to claim 1, wherein the fuel nozzle is a main fuel nozzle that blows lean fuel into a pilot fuel nozzle provided at the head of the combustion chamber and a premixing duct disposed around the pilot fuel nozzle. These fuel nozzles have a pressure spray type fuel ejection nozzle that continuously ejects pressurized liquid fuel, and a fuel atomization air is injected into the liquid fuel from around the fuel ejection nozzle to mix. A gas turbine plant comprising an air supply nozzle for atomizing fuel. 3. The gas turbine plant according to claim 1, wherein a rotation speed of the compressor for atomizing liquid fuel is controlled based on a rotation speed of a turbine shaft. 4. The gas turbine plant according to claim 1, wherein the number of revolutions of the compressor for atomizing liquid fuel is controlled based on the plant output. 5. The gas turbine plant according to claim 1, wherein the rotation speed of the compressor for atomizing the liquid fuel is controlled based on both the rotation speed of the turbine shaft and the plant output. Gas turbine plant. 6. The gas turbine plant according to claim 1, wherein the number of revolutions of the compressor for atomizing the liquid fuel is controlled based on combustion vibration in the combustor. 7. The gas turbine plant according to claim 1, wherein the number of revolutions of the compressor for atomizing the liquid fuel is controlled based on both factors of combustion vibration in the combustor and the number of revolutions of the turbine shaft. A gas turbine plant characterized by the above. 8. The gas turbine plant according to claim 1, wherein the number of revolutions of the liquid fuel atomization compressor is controlled based on both factors of combustion oscillation in the combustor and plant output. And a gas turbine plant. 9. The gas turbine plant according to claim 1, wherein the number of revolutions of the compressor for atomizing the liquid fuel is controlled based on three factors: combustion vibration in the combustor, the number of revolutions of the turbine shaft, and plant output. A gas turbine plant having a configuration. 10. The gas turbine plant according to claim 1, wherein the liquid fuel atomizing compressor and the fuel nozzle of the combustor are connected by an atomizing air supply pipe. A gas turbine plant comprising a flow control orifice at an intermediate position. 11. The gas turbine plant according to claim 10, wherein the atomizing air supply pipe connecting the liquid fuel atomizing compressor and the fuel nozzle of the combustor corresponds to the pilot fuel nozzle and the main fuel nozzle. A gas turbine plant comprising a plurality of gas turbines. 12. The gas turbine plant according to claim 11, wherein the atomizing air supply pipe connecting the liquid fuel atomizing compressor and the fuel nozzle of the combustor corresponds to the pilot fuel nozzle and the main fuel nozzle. A gas turbine plant comprising a plurality of gas turbines and a flow control orifice provided in each of the atomizing air supply pipes. 13. The gas turbine plant according to any one of claims 10 to 12, wherein the air discharged from the liquid fuel atomizing compressor is branched from the atomizing air supply pipe and the liquid fuel atomizing compressor is compressed. A gas turbine plant comprising: an air return pipe for atomization for returning to the suction side of the machine; and a flow control valve provided at an intermediate portion of the air return pipe for atomization. 14. A gas turbine plant which atomizes liquid fuel by mixing with air, blows the atomized liquid fuel into a combustor and burns the fuel, and drives a gas turbine with the combustion gas. Supply air to the tip of the fuel nozzle of the combustor as a high-speed stream pressurized by the liquid fuel atomization compressor, when the gas turbine rotation speed is high, the liquid fuel atomization compressor Driven by the turbine shaft,
An air supply pipe for atomization with a flow control orifice according to any one of claims 10 to 12, wherein the gas turbine is driven by a separate motor-driven auxiliary compressor when the rotation speed of the gas turbine is low. 14. A gas turbine plant, comprising: an air return pipe for atomization with a flow control valve according to claim 13.