JPH05149544A - Controller for gas turbine - Google Patents

Abstract

PURPOSE:To stabilize flame upon intercepting a load and reduce a peak rotating speed by a method wherein a first main nozzle is controlled in accordance with the load, then, a second main nozzle is controlled and a pilot nozzle distribution valve is opened and/or closed in accordance with the operating conditions of a gas turbine. CONSTITUTION:A first main nozzle function generator 17 outputs a first main nozzle control signal to a tracking circuit 19 based on a load speed control signal and a second main nozzle function generator 18 outputs a second main nozzle control signal to the tracking circuit 19 based on the outlet port temperature of a burner 3. The tracking circuit 19 outputs a third main nozzle control signal, in which the second main nozzle control signal follows the first main nozzle control signal, into a main nozzle distributing valve 13. A pilot nozzle function generator 20 inputs the third main nozzle control signal and operates a pilot nozzle distributing valve 11. According to this method, flame is stabilized even upon the sudden change of the flow rate of fuel and the peak number of rotations can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is incorporated in a gas turbine plant or a combined cycle power plant.
The present invention relates to a staged combustion gas turbine controller.

[0002]

2. Description of the Related Art A gas turbine combustor is incorporated in a gas turbine plant or a combined cycle power plant. Combustion gas from the gas turbine combustor is introduced into the gas turbine to drive the gas turbine. In this type of gas turbine, it is known that increasing the inlet temperature of the turbine improves the thermal efficiency of the turbine. However, when the inlet temperature of the gas turbine combustor is increased, NOx (nitrogen oxide) increases.

As a means for reducing NOx generated in order to solve this, a two-stage combustion means is adopted. This is equipped with a pilot nozzle and a main nozzle in the combustor, and while performing stable diffusion combustion with the pilot nozzle,
Premixed combustion is performed in the main nozzle, and the stable flame of the pilot nozzle stably burns the lean premixed gas that is difficult to burn in the main nozzle.

FIG. 5 shows the structure of a control device for a gas turbine power plant using the above-mentioned two-stage combustion means.

This gas turbine power plant comprises a compressor 1, a gas turbine 2, a combustor 3, a denitration device 4, a load speed controller 5, a control calculator 6, and the like. A shutoff valve 8, a control valve 9 and a flow rate detector 10 are arranged in the fuel pipe 7, and a pilot nozzle pipe 7 branched from the fuel pipe 7 is provided.
a is a pilot nozzle distribution valve 11 and a flow rate detector 12
Are arranged, and the main nozzle distribution valve 13 is arranged in the main nozzle pipe 7b. Further, the temperature detector 14 is provided on the inlet side of the compressor 1, and the pressure detector 1 is provided on the outlet side.
5. Temperature detectors 16 are arranged on the outlet side of the gas turbine 2, respectively.

With the above construction, the total flow rate of the fuel pipe 7 is controlled by opening and closing the control valve 9 based on the load speed control signal VCE of the load speed controller 5.

That is, the load speed controller 5 is constructed as shown in FIG. 6, and the actual load value 5a and the load set value 5b are added / subtracted by the adder / subtractor 5c and input to the load setter 5d. The load setter 5d integrates the input signal and outputs it to the adder / subtractor 5e.

On the other hand, the setting signal of the speed setter 5f and the speed detection signal r are added / subtracted by the adder / subtractor 5g, the added / subtracted value is multiplied by the multiplier 5h, and further input to the adder / subtractor 5e. In the adder / subtractor 5e, the respective signals described above and the bias signal of the bias setter 5j are added / subtracted by the symbols shown and output as the load speed control signal VCE.

Here, normally, the load speed controller 5 is
The load speed control signal VCE is output so that the actual load value 5a follows the load set value 5b, and the control valve 9 is opened and closed. On the other hand, the respective detection signals of the temperature detector 14, the pressure detector 15, the temperature detector 16 and the detection signals of the flow rate detector 10 and the flow rate detector 12 are input to the control arithmetic unit 6 and predetermined by the control arithmetic unit. After calculation processing, the pilot fuel control signal and the main fuel control signal are output to the corresponding pilot nozzle distribution valve 11 and main nozzle distribution valve 13, respectively.

In this case, fuel distribution between the pilot nozzle distribution valve 11 and the main nozzle distribution valve 13 is performed as shown in FIG. That is, when the load is small, the pilot fuel bears all the fuel, and when the load becomes large, the main fuel and the pilot fuel bear all the fuel at the ratio shown in the figure. At this time, the combustor outlet temperature with respect to the load increases as the load increases and becomes saturated, as shown in FIG. Thus, even when the gas turbine 2 is in a high load state, the fuel flow rate ratio from the pilot nozzle distribution valve 11 and the main nozzle distribution valve 13 is controlled to reduce NOx.

[0011]

However, the above-described two-stage combustion gas turbine control device has the following problems.

First, in the case of load shedding and the like, there is a problem that pilot combustion control is distributed as shown in FIG. 7 due to delay in detection by the flow rate detector 10 and the pilot nozzle misfires. That is, in this case, the load speed control signal VCE from the load speed controller 5 rapidly decreases to throttle the control valve 9 to a predetermined value. However, since the detection of the flow rate detector 10 is delayed, the pilot nozzle distribution valve 11 is detected based on the detection signal of the flow rate detector 10.
Response to the pilot fuel control signal is delayed. Therefore, the combustion of the pilot nozzle may not be properly controlled, and the combustion of the pilot nozzle may disappear. Once the combustion of the pilot nozzle is extinguished, the flame of the pre-mixture on the main nozzle side is also extinguished, and it becomes impossible to ignite again and the gas turbine is misfired.

Secondly, there is a problem that the overspeed value of the gas turbine 2 becomes high when the load is cut off due to the piping volume of the measuring straight pipe portion provided in the flow rate detector 12 on the pilot nozzle side. That is, when the load is cut off, the control valve 9 is throttled by the load speed control signal VCE, but the fuel in the piping portion of the measuring straight pipe portion is supplied to the combustor 3, so that the overspeed value of the gas turbine 2 is further increased. ..

Therefore, it is an object of the present invention to provide a gas turbine control device capable of maintaining a stable flame even when the fuel flow rate suddenly changes such as load shedding and further reducing the peak rotational speed.

[0015]

According to the present invention, a fuel supply amount to a pilot nozzle of a combustor and a fuel supply amount to a main nozzle of the combustor are set to a predetermined fuel supply distribution ratio according to a load of a gas turbine. In order to achieve this, a pilot nozzle distribution valve is controlled by a pilot nozzle control signal, and a main nozzle distribution valve is controlled by a main nozzle control signal to burn the pilot nozzle and the main nozzle in two stages. A first main nozzle function unit that outputs a first main nozzle control signal based on a predetermined function value according to the load, and a second main nozzle control signal based on a predetermined function value according to the operating state of the gas turbine And a second main nozzle function unit for outputting the second main nozzle control signal to the first main nozzle control signal to follow the second main nozzle control signal. A tracking circuit that outputs a slur control signal and a control signal based on a predetermined function value for opening and closing the pilot nozzle distribution valve according to the third main nozzle control signal are output, and this signal is used as a pilot nozzle control signal. A pilot nozzle function unit and means for using the third main nozzle control signal as a main nozzle control signal are provided.

[0016]

With the above structure, the second main nozzle control signal follows the first main nozzle control signal according to the load in accordance with the operating state of the gas turbine, and outputs the third main nozzle control signal. The third main nozzle control signal opens and closes the main nozzle distribution valve to control the main nozzle fuel flow rate. On the other hand, the pilot nozzle distribution valve is controlled by the pilot fuel control signal based on a predetermined function value in the third main nozzle control signal. Therefore, stable two-stage combustion is performed, and when the load is cut off, the pilot nozzle distribution valve has a predetermined opening, so that the pilot nozzle does not misfire, and the turbine speed is prevented from increasing.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a control apparatus for a gas turbine showing an embodiment of the present invention. The same reference numerals as those in FIG. 5 indicate the same or corresponding portions. The difference from FIG. 5 is that the flow rate detector 12 is deleted, and in addition, instead of the control calculator 6, a first main nozzle function unit 17, a second main nozzle function unit 18, a tracking circuit 19, a pilot nozzle. This is the point where the function unit 20 is provided.

In this embodiment, in order to determine the flow rate ratio of the pilot nozzle and the main nozzle, the load speed control signal V
A third main nozzle control signal f3 obtained by causing the first main nozzle control signal f calculated from CE to follow the second main nozzle control signal f2 calculated based on the gas turbine exhaust gas temperature, the compressor outlet pressure, etc. A means for generating the pilot nozzle distribution valve 11 and the main nozzle distribution valve 13 are controlled based on the third main nozzle control signal f3.

Here, the first main nozzle function unit 17
Inputs the load speed control signal VCE and outputs it to the tracking circuit 19 as a first main nozzle control signal f1 having a function value as shown in FIG. The second main nozzle function unit 18 includes detection signals of the temperature detector 14 on the outlet side of the compressor 1, the pressure detector 15 on the inlet side of the compressor 1, the exhaust gas temperature detector 16 of the gas turbine 2, and the like. The combustor outlet temperature Tf is calculated based on the above, and the combustor outlet temperature Tf is output to the tracking circuit 19 as the second main nozzle signal control f2 having a function value as shown in FIG.

The tracking circuit 19 outputs the third main nozzle control signal f3 to the pilot nozzle function unit 20 while the second main nozzle control signal f2 follows the first main nozzle control signal f1 while outputting the main nozzle. Output to the distribution valve 13. The pilot nozzle function unit 20 controls the pilot nozzle distribution valve 11 by outputting a predetermined function value according to a pilot nozzle control signal.

With the above configuration, the load speed controller 5 uses the load speed control signal VCE based on the load set value 5b shown in FIG.
Is output, whereby the control valve 9 is opened and closed to control the total fuel flow rate. Furthermore, the load speed control signal VCE
Is input to the first main nozzle function unit 17 shown in FIG. 1, and as shown in FIG. 2, the first main nozzle control signal f1 whose output signal gradually increases and saturates in accordance with the load speed control signal VCE is tracked. It is input to the circuit 19.

On the other hand, in the second main nozzle function unit 18, the temperature detector 14, the pressure detector 15, and the temperature detector 16
Of each of the above, the combustor outlet temperature Tf is calculated, and the second main nozzle control signal f2 that gradually increases and saturates in accordance with the combustor outlet temperature Tf as shown in FIG. Is entered.

Next, the operation of the tracking circuit 19 will be described with reference to FIG.
Will be described.

In the tracking circuit 19, the adder / subtractor 19
At a, the first main nozzle control signal f1 and the second main nozzle control signal f2 are added or subtracted, and this value is input to the limit setter 19b. In the limit setter 19b,
As shown in the figure, the upper limit and the lower limit are limited by the function value, and integration is performed by the next integrator 19c. The output signal of the integrator 19c is output to the first main nozzle control signal f1 by the adder / subtractor 19d.
Is added / subtracted as the third main nozzle control signal f3, and the pilot nozzle function unit 20 and the main nozzle distribution valve 13 are added.
Is output to.

Here, the first main nozzle control signal f1
And the second main nozzle control signal f2 change at the same value, the output signal of the integrator 19c is almost 0 and the adder / subtractor 1
9d outputs the third main nozzle control signal f3 which is the same as the first main nozzle control signal f1. However, the second main nozzle control signal f2 and the first main nozzle control signal f1 corresponding to the operating state of the gas turbine 2 are used.
If there is a difference between and, the integrator 19c outputs the integrated output signal to the adder / subtractor 19d, and the third main nozzle control signal f3 increases or decreases from this result. As a result, the optimum third main nozzle control signal f3 corresponding to the operating state of the gas turbine 2 is output and the first main nozzle control signal f
The second main nozzle control signal f2 follows 1

The pilot nozzle function unit 20 outputs a signal represented by the following equation (1) to the pilot nozzle distribution valve 11.

[0028]

[Equation 1] f4 = 1-f3 (1)

As a result, as in the case of FIG. 7, the load is controlled by the ratio of the pilot fuel and the main fuel in the total fuel.

By the way, when the load is cut off, the load speed control signal VCE is drastically lowered, the control valve 9 is throttled to a predetermined value, and the first main nozzle control signal f1 and the first main nozzle control signal f1 from the first main nozzle function unit 17 are supplied. The main nozzle control signal f2 of 2 has a low value as shown in FIGS. 2 and 3,
Since the signal represented by the above formula (1) is output to the pilot nozzle distribution valve 11, a predetermined value of pilot nozzle fuel is supplied to the combustor 3 as shown in FIG. 7.

As described above, the compressor outlet temperature, the compressor outlet pressure, and the turbine exhaust temperature representing the operating state of the gas turbine with respect to the flow rate ratio signals of the pilot combustion nozzle and the main combustion nozzle calculated from the load speed control signal VCE. The flow rate ratio can be approximated by the two-stage combustion means optimally set for the combustor outlet temperature obtained from the above. Therefore, the pilot nozzle will not misfire when shut off,
The NOx and Co concentrations discharged from the combustor can be reduced.

[0032]

As described above, according to the present invention, the pilot nozzle does not misfire when the load is cut off. Further, the speed of the turbine can be prevented when the load is cut off. In addition, the NOx and Co concentrations can be reduced because the combustor is distributed so as to approach optimum mixing.

[Brief description of drawings]

FIG. 1 is a system diagram of a gas turbine control device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a first main nozzle function unit of the same device.

FIG. 3 is an explanatory diagram of a second main nozzle function unit of the same device.

FIG. 4 is a configuration diagram of a tracking circuit of the device.

FIG. 5 is a system diagram of a conventional gas turbine control device.

FIG. 6 is a configuration diagram of a load speed controller of the device.

FIG. 7 is an explanatory diagram showing a fuel distribution ratio with respect to a load of two-stage combustion of the device.

FIG. 8 is an explanatory diagram showing a combustor outlet temperature with respect to a load of the apparatus.

[Explanation of symbols]

 2 Gas turbine 3 Combustor 5 Load speed controller 9 Control valve 10 Flow rate detector 11 Pilot nozzle distribution valve 13 Main nozzle distribution valve 17 First main nozzle function unit 18 Second main nozzle function unit 19 Tracking circuit 20 Pilot nozzle Function device

Claims (1)

[Claims] 1. A pilot nozzle distribution valve is provided to adjust a fuel supply amount to a pilot nozzle of a combustor and a fuel supply amount to a main nozzle of a combustor to a predetermined fuel supply distribution ratio according to a load of a gas turbine. In a gas turbine control device configured to control a pilot nozzle control signal and a main nozzle distribution valve by a main nozzle control signal to burn the pilot nozzle and the main nozzle in two stages, a predetermined value is set according to a load. A first main nozzle function unit that outputs a first main nozzle control signal based on the function value of the second main nozzle, and a second main nozzle control signal that outputs a second main nozzle control signal based on a predetermined function value according to the operating state of the gas turbine. A main nozzle function unit, and a third main nozzle that causes the second main nozzle control signal to follow the first main nozzle control signal. A tracking circuit for outputting a control signal, and a control signal based on a predetermined function value for opening and closing the pilot nozzle distribution valve in response to the third main nozzle control signal, and the signal is output as the pilot nozzle control signal. And a means for using the third main nozzle control signal as the main nozzle control signal.