JPH06213456A - Combustion device for gas turbine and its fuel control device - Google Patents

Abstract

PURPOSE:To effect a low NOx combustion by a method wherein even a part of pilot fuel is ignited as a pre-mixed gaseous fuel. CONSTITUTION:A pilot fuel pre-mixed gas pipe 14 enclosing an extremity end of a pilot injection valve 3 is arranged. The pilot injection valve 3 is constructed to have a multi-passage comprising a first passage 10 for supplying pilot fuel for dispersion combustion and a second passage 12 for supplying pilot fuel for pre-mixing gas combustion. A combustion device for the gas turbine is provided with each of glow plugs 15, 16 arranged near an outlet of the pilot injection valve and near an outlet of the pre-mixtured gas pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion system in accordance with a change in load, and more particularly, a combustion region of pilot fuel is switched from a diffusion combustion system to a premixed gas combustion system or from a premixed gas combustion system to a diffusion combustion system. The present invention relates to a gas turbine combustor and a fuel control device for the combustor.

[0002]

2. Description of the Related Art Generally, as a method of reducing nitrogen oxides (NOx) in exhaust gas discharged from a gas turbine, a pretreatment method for suppressing generation of NOx in a combustion process and a posttreatment by a flue gas denitration device are performed. The pretreatment method includes a: water or steam injection method, b: lean diffusion combustion method, c:
Preheat generation, premixed combustion method, d: two-stage combustion method, e: catalytic combustion method, etc.

However, during these methods, the thermal efficiency decreases and the N
There are various practical problems such as low Ox reduction rate, poor flame stability, low mechanical strength, and low reliability. Therefore, the inventors of the present invention housed a combustion cylinder having a diffusion combustion region, a premixed gas combustion region, and a main combustion region in the combustor body, and provided a pilot injection valve at the top of this combustion cylinder, A plurality of premixed gas pipes that communicate with the premixed gas combustion region are arranged around, and a fuel injection nozzle is further arranged in the premixed gas pipe, and a fuel injection nozzle that injects fuel according to the load of the gas turbine We first proposed a combustor for a gas turbine that selects the number of operating lines.

That is, as shown in FIGS. 7 and 8, the pilot injection valve 3 and the swirler 4 are provided at the center of the top of the combustor body 1.
And are provided. The combustion cylinder 2 is a portion forming a pilot flame, that is, a small diameter portion 2a forming a diffusion combustion region B.
And an intermediate conical portion 2b forming a premixed combustion region C,
It is composed of a large diameter portion 2c forming a main combustion region D. Then, one ends of a plurality of premixed air tubes 6 are attached to the intermediate conical portion 2b forming the combustion cylinder 2, and the outlet 6a thereof is provided.
Open in the premixed gas combustion region C. A plurality of the premixed trachea 6 are arranged around the combustion cylinder 2 at equal intervals, and in this example, six are arranged at equal intervals as shown in FIG. Further, a fuel injection nozzle 7 is arranged in the premixed gas pipe 6.

As shown in FIG. 9 in which a load is drawn on the horizontal axis, when the gas turbine is in a low load operation (0 to 50%) from startup, the pilot is used to measure the stability of the flame. Premixing is performed by injecting fuel from the injection valve 3 to perform diffusion combustion, reducing the amount of fuel supplied from the pilot injection valve 3 and supplying fuel from the fuel injection nozzle 7 in the premix tube 6 during high load operation. It is what makes the air burn. In this case, the two fuel injection nozzles 7 corresponding to each other in the diametrical direction form a set, and the number of the fuel injection nozzles 7 is controlled so as to increase or decrease in stages of 2, 4, and 6.

[0006]

However, in the above-described gas turbine combustor, the diffusion combustion range for obtaining flame stability is relatively wide, and therefore the NOx value is relatively high. . That is, although diffusion combustion can perform stable combustion, there is a problem that the NOx value becomes high.

According to the knowledge of the present inventors, the load is 50%.
In the above case, a part or all of the pilot fuel is premixed and combusted to reduce the amount of NOx generated in the pilot diffusion combustion. That is, it has been confirmed that the total exhausted NOx can be reduced, and the present invention provides a combustor for a gas turbine and a fuel control device utilizing this knowledge.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and provides a diffusion combustion region, a premixed combustion region and a main combustion region in the combustor body. In a combustor for a gas turbine, which accommodates a combustion cylinder having, a pilot injection valve is provided at the top of the combustion cylinder, and a plurality of premixed gas pipes communicating with the premixed gas combustion region are arranged around the combustion cylinder, A pilot fuel premix air pipe surrounding the tip portion of the pilot injection valve is arranged, and the pilot injection valve is supplied with a first passage for supplying pilot fuel for diffusion combustion and pilot fuel for premix air combustion. A gas turbine having a multi-passage consisting of a second passage and a glow plug disposed near the pilot injection valve outlet and near the premixed tracheal outlet, respectively. And use combustor, there is provided St. control device of the fuel supplied to the combustor.

[0009]

[Operation] In such a gas turbine combustor, the fuel supplied from the first passage of the pilot injection valve is ignited by the glow plug when the gas turbine is started or the load is cut off, and stable combustion is achieved by diffusion combustion. During the load operation of the gas turbine, the premixed fuel supplied from the second passage of the pilot injection valve and the premixed fuel supplied from the premixed pipe are ignited and burned by the glow plugs respectively. Combustion can be performed, and low NOx combustion can be performed.

[0010]

EXAMPLE An example of a gas turbine combustor and a fuel control system therefor according to the present invention will be described below with reference to FIGS. In these figures, the same symbols as those in FIGS. 7 and 8 indicate the same names. FIG. 1 is a side sectional view of a combustor for a gas turbine, in which a pilot injection valve 3 provided at the top of a combustor body 1 particularly constitutes a multiple pipe line.
That is, the tip of the pilot injection valve 3 is connected to the combustion cylinder 2, the inner pipe 11 forming the first passage 10 for supplying the pilot fuel F ₁ for diffusion combustion to the diffusion combustion region B, and the premixed gas combustion. Forming a second passage 12 for supplying the pilot fuel F ₂ for use in the diffusion combustion region B and communicating hole 13
And the outer pipe 14 having the above are formed as multiple pipe lines arranged concentrically. Then, in the vicinity of the outlet of the pilot injection valve 3, specifically, in the diffusion combustion region B, and also in the premixed gas pipe 6
A first glow plug 15 which is a pilot glow plug and a second glow plug 16 which is a premixed gas glow plug are arranged in the vicinity of the outlet of the above, that is, in the premixed gas combustion region C.

That is, a premixed gas pipe 17 for pilot fuel is provided at the top of the combustion cylinder 2 so as to cover the periphery of the tip of the pilot injection valve 3. In the above structure, when the gas turbine (not shown) is started or the load is cut off, the pilot fuel F ₁ is supplied from the first passage 10 into the diffusion combustion region B and ignited by the first glow plug 15. Burned.

When a load is applied to the gas turbine, the pilot fuel F ₂ is supplied from the second passage 12 through the communication hole 13 into the premix gas pipe 17, where it is mixed with the air a and the premix fuel F _{3 is} mixed. And is supplied to the diffusion combustion area B,
Here, the first glow plug 15 ignites and burns. In addition, depending on the operating method, pilot fuels F ₁ and F
₂ and are simultaneously supplied and burned.

On the other hand, during the load operation of this gas turbine, the premixed gas fuel F ₄ which is the main fuel is supplied from the premixed gas pipe 6 to the premixed gas combustion region C, and in the main combustion region C by the second glow plug 16. Burned. FIG. 2 shows the relationship between the fuel supply amount and the turbine load. The pilot fuels F ₁ and F ₂ are supplied in the no-load range from the start of the turbine. It is burned to the state using the pilot injection valve 3. And the load 1
Combustion by the premixed trachea 6 is performed in the section from / 2 to the full load.

The fuel for the gas turbine combustor is
It is controlled by a signal from the controller of the gas turbine. This control device will be described. As shown in FIG. 3, it is configured by additionally connecting a fuel distribution device 22 to the fuel control device 21. More specifically, the fuel control device 21 is
Flow control valve 23 in which sluice valves 23a and 23b are arranged in front and rear
an exhaust pipe 25 having a main fuel pipe line 24 having c, and a sluice valve 23d for discharging the fuel remaining between the sluice valve 23a and the flow control valve 23c when the flow control valve 23c is closed, and It is configured by a control device (not shown) for controlling these according to the operating state of the turbine. The fuel control device 21 is attached to a conventional gas turbine combustor.

In the fuel distribution system 22, the main fuel line 24 is branched into a pilot fuel line 26 and a premixed gas line 27, and the pilot fuel line 26 is connected to the first switching valve 2
8, a first pilot fuel pipe line 29 including a branch pipe 30 having a branch pipe 32 having a first constant flow valve 31 whose flow rate is automatically determined by spring pressure and the like, and a second gate valve 33.
And a second pilot fuel line 35 having a second constant flow valve 34.

The first pilot fuel line 29 is connected to the first passage 10 of the pilot injection valve 3, and the second pilot fuel line 35 is connected to the second passage 12 of the pilot injection valve 3. ing. In the premixed air line 27, the wake side of the first sluice valve 36 for emergency shutoff is the first line 4
0, the second pipeline 41, and the third pipeline 42,
The pipeline having the second switching valve 37 is branched to the pipeline 40, the second pipeline 41 has the third switching valve 38, and the wake side is branched into two. Further, a fourth switching valve 39 is provided in the third pipe 42, and the fourth switching valve 39 is branched into two on the downstream side. These first pipeline 40 and second pipeline 41
And the third conduit 42 are respectively arranged in the fuel injection nozzle 7 arranged in the premixed gas pipe 6 in the diametrical direction shown in FIG.
Books are connected as a pair.

Then, the first switching valve 28 and the second switching valve 3
7 is configured to operate in reverse for switching between the first passage 10 of the pilot injection valve 3 and the fuel injection nozzle 7. Reference numeral 43 denotes a fuel distributor, which receives signals such as a load cutoff signal S ₁ , a load signal S ₂ , an atmospheric temperature S ₃ , and a CDP signal S ₄ via a pressure converter 44. First to fourth switching valves 28, 37, 38, 3
9 and the first sluice valve 36 and the second sluice valve 33 are configured to be controlled.

In the fuel control device for a gas turbine combustor having such a structure, when the gas turbine is "started up or no load", the branch pipes 30 and 32 are connected from the first pilot fuel line 29 to the pilot injection valve 3. Fuel is supplied through. Then, at the “load occurrence”, the second sluice valve 33 is opened and the fuel provided in each premixed air pipe 6 from the second pilot fuel pipe line 35 to the pilot injection valve 3 and from the premixed air pipe line 27. The premixed fuel is supplied to the injection nozzle 7 depending on the load and burned.

In this case, as shown in FIG. 4, for example, when the turbine load is 50% or less, the pilot diffusion combustion region a and the pilot diffusion combustion region a and the main diffusion combustion region a when the load is about 50% to 75%. The premixed combustion region c of
Further, for a load of 75% to 100%, the fuel ratio is controlled so that the main premixed combustion region c and the pilot premixed combustion region b exist.

FIG. 5 shows another embodiment of the fuel control device, and the same reference numerals as those in FIG. 3 denote the same names. In the present embodiment, one end of the second pilot fuel pipeline 35a is connected to the first pipeline 40 that constitutes the premix gas pipeline 27. That is, the main premixed gas pipeline 27 and a part of the fuel are used as pilot fuel. In this case, as shown in FIG.
The fuel ratio is controlled so that the pilot premixed combustion region b and the main premixed combustion region c exist for a load of not less than%.

[0021]

The gas turbine combustor according to the present invention accommodates a combustion cylinder 2 having a diffusion combustion region B, a premixed gas combustion region C and a main combustion region D in a combustor body 1 and A pilot injection valve 3 is provided on the top of the cylinder 2,
In a combustor for a gas turbine in which a plurality of premixed gas pipes 6 communicating with the premixed gas combustion region C are arranged around the combustion cylinder 2, a premixed fuel for pilot fuel surrounding a tip end portion of the pilot injection valve 3 is provided. A trachea 14 is arranged, and the pilot injection valve 3 is provided with a multi-passage including a first passage 10 for supplying pilot fuel for diffusion combustion and a second passage 12 for supplying pilot fuel for premixed combustion. And a glow plug 15 near the exit of the pilot injection valve and near the exit of the premix air pipe, respectively.
16 are arranged. Therefore, since the main fuel is burned as the premixed fuel and a part of the pilot fuel is also burned as the premixed fuel, there is an effect that low NOx combustion is possible.

[Brief description of drawings]

FIG. 1 is a side sectional view of a main part of a gas turbine combustor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a fuel ratio and a load.

FIG. 3 is a system diagram of a fuel control device.

FIG. 4 is a diagram showing the relationship between the fuel ratio and the load.

FIG. 5 is a system diagram of another embodiment of the fuel control device.

FIG. 6 is a diagram showing the relationship between the fuel ratio and the load.

FIG. 7 is a side sectional view of a conventional gas turbine combustor.

FIG. 8 is a view on arrow XX in FIG. 7.

FIG. 9 is a diagram showing a relationship between fuel supply pressure and load.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Combustor main body 2 Combustion cylinder 3 Pilot injection valve 6,17 Premix air tube 7 Fuel injection nozzle 10 First passage 11 Inner pipe 12 Second passage 13 Communication hole 14 Outer pipe 15 First glow plug 16 Second Glow plug 21 Fuel control device 22 Fuel distribution device 24 Main fuel line 26 Pilot fuel line 27 Premix gas line 28 First switching valve 29 First pilot fuel line 30, 32 Branch pipe 31 First constant flow rate Valve 33 Second gate valve 34 Second constant flow valve 35 Second pilot fuel line 36 First gate valve 37 Second switching valve 38 Third switching valve 39 Fourth switching valve 40 First valve Pipe line 41 Second pipe line 42 Third pipe line 43 Fuel distribution control device

Claims (3)

[Claims] 1. A combustion cylinder 2 having a diffusion combustion region B, a premixed combustion region C and a main combustion region D is housed in a combustor body 1, and a pilot injection valve 3 is provided on the top of the combustion cylinder 2. In addition, in a combustor for a gas turbine in which a plurality of premixed gas pipes 6 communicating with the premixed gas combustion region C are arranged around the combustion cylinder 2, for a pilot fuel surrounding a tip end portion of the pilot injection valve 3. A premixed gas pipe 14 is arranged, and the pilot injection valve 3 is provided with a first passage 10 for supplying pilot fuel for diffusion combustion and a second passage 12 for supplying pilot fuel for premixed air combustion. A combustor for a gas turbine, characterized in that it is configured to have a passage, and glow plugs 15 and 16 are arranged near the pilot injection valve outlet and near the premixed gas pipe outlet, respectively. 2. A fuel distribution device 22 is additionally connected to a fuel control device of a gas turbine combustor having a flow control valve 23, and the fuel supplied to the combustor 1 is controlled via the fuel distribution device 22. The distributor 22 is branched into a pilot fuel line 26 and a premixing line 27 having a first sluice valve 36.
Reference numeral 6 denotes a first pilot fuel line 29 having a first switching valve 28 and a first constant flow valve 31, and a second pilot having a second sluice valve 33 and a second constant flow valve 34. The premixed combustion line 27 is composed of a fuel line 35, and the first, second and third lines 40, 41 and 42 are provided with second, third and fourth switching valves 37, 38 and 39. The first and second pilot fuel pipe lines 29 and 35 are connected to the injection nozzle of the pilot valve 3 and the first, second and third pipe lines 4 are formed.
0, 41, 42 are the fuel injection nozzles 7 of the premixed gas supply pipe 6.
, And the first switching valve 28 is a valve that operates in reverse to the second switching valve 37. The first and second sluice valves 36, 37 and the respective switching valves 28, 37, 38 are A fuel control device for a gas turbine combustor, which is controlled by a signal from a fuel distribution control device 43 which operates in response to a signal from a control device for a gas turbine. 3. A fuel distribution device 22 is additionally connected to a fuel control device of a gas turbine combustor having a flow control valve 23, and the fuel supplied to the combustor is controlled via this fuel distribution device 22. In the device, the distribution device 22 is branched into a premix gas line 27 having a sluice valve 36 and a pilot fuel line 26, and the premix fuel line 27 is divided into a second and a second.
First and third switching valves 37, 38 and 39 are provided.
It is composed of a few conduits 40, 41, 42, and the pilot fuel conduit 26 is connected to the first switching valve 28 and the first constant flow valve 3.
1 and a second pilot fuel pipe line 29 having a second constant flow valve 34, one end of which is connected to the pipe line 26, and The first and second pilot fuel pipe lines 29 and 35 are connected to the injection nozzle of the pilot injection valve 3 and
, 40, 41, 42 are connected to the fuel injection nozzle 7 of the mixture supply pipe 6, and the first switching valve 28 is connected to the second
Of the sluice valve 3 and the switching valve 37 of FIG.
6, 33, and the switching valves 28, 37, 38, 39 are controlled by signals of a fuel distribution control device 43 that operates by receiving signals from the control device of the gas turbine. .