JPS58107819A - Gas turbine control device - Google Patents

Abstract

PURPOSE:To obtain an efficient operation even if the combustion condition varies in a device controlling the fuel in accordance with a turbine exhaust gas temperature curve with a turbine inlet temperature kept constant by detecting the combustion condition to correct said curve. CONSTITUTION:The measured temperature signal 13 of the gas turbine exhaust gas is subtracted from the signal of a turbine exhaust gas temperature curve setter 14 by means of an adder/subtractor 15 and is input into a proportional integrator 16 to give the first fuel control signal 25a. On the other hand, the deviation signal between the measured speed signal 17 and speed setting signal 18 is corrected in an adder/subtractor 23 by means of the deviation signal between an actual load signal 19 and load command signal 20, and the second fuel control signal 25b is generated in a proportional calculator 24. A lower value between the above two signals 25a, 25b is selected by a lower value preference circuit 25, and the fuel is controlled based on the signal. In this case, the steam flow is detected by a flow meter 26 and is input into a corrector 27, and a correction signal is output from a function generator 28 and is added to the signal of said setter 14 by means of an adder/subtractor 29.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a first fuel control signal according to a predetermined turbine exhaust gas temperature curve so that the turbine inlet temperature becomes a predetermined temperature, and a turbine speed deviation signal to a load deviation signal. The present invention relates to a gas turbine control device that selects a second fuel control signal corresponding to a signal modified by using a low value priority circuit, and performs fuel control based on the selected fuel control signal.

TECHNICAL BACKGROUND OF THE INVENTION In recent years, gas turbines have attracted attention for several reasons: by configuring them as combined cycle power plants, it is possible to obtain high thermal efficiency that cannot be obtained with conventional thermal power plants.

However, if the amount of nitrogen oxides (hereinafter referred to as NOx) contained in the combustion gas of a gas turbine is large and exceeds the regulation value, some people say that countermeasures are required.

FIG. 1 shows the configuration of a gas turbine device in which a method of introducing steam or water into a gas turbine combustor is adopted as a NOx countermeasure. The gas turbine 2 is directly connected to (2) a compressor 1 and a driven machine 4 such as a generator, and drives them. The compressor 1 sucks air 5 from the atmosphere, compresses it, and sends the compressed air 6 to the combustor 3. send to

Further, the fuel 7 is supplied by a fuel control valve 8, and the steam 9 is supplied by a control valve 10.
The flow rate is controlled by and sent to the combustor 3. In the combustor 3, fuel 7 is combusted by compressed air 6 and high temperature combustion gas 11 is produced.
f. Generate. Steam 9 is injected into the combustor 3 to lower the temperature of the combustion gases and reduce the generation of NOx. High-temperature combustion gas 11 coming out of the combustor 3 is sent to the gas turbine 2, where it performs expansion work. Turbine exhaust gas 1
2 is either dumped into the atmosphere or sent to other equipment (e.g. heat recovery boiler).

In the compressor 1 of the gas turbine 2, the intake air amount increases as the atmospheric temperature decreases, so the turbine inlet pressure increases, and the compressor discharge pressure PD also increases accordingly. Therefore, when the turbine inlet temperature is constant, when the atmospheric temperature decreases, the turbine pressure ratio increases and the temperature difference between the turbine inlet and outlet increases, so the turbine exhaust gas temperature decreases (3). This will be explained in detail using FIG.

FIG. 2 shows an operating curve of the turbine inlet temperature T1 and the exhaust gas temperature T, l, and the horizontal axis is the discharge pressure PD of the compressor 1. For example, when the atmospheric temperature is high, the turbine inlet temperature T1 operates at point A and the exhaust gas temperature T2 operates at the lower point. As the atmospheric temperature decreases, the compressor discharge pressure also increases, so the inlet temperature T, i Point A → Point B →
If point C → point D is constant, the exhaust gas temperature T is from point F →
Since the inlet temperature T of the gas turbine 2 and the exhaust gas temperature T2 exhibit the characteristics described above, in the conventional control system, when the turbine inlet temperature Trk is constant, Fuel control is performed according to the curve of turbine exhaust gas temperature T2.

Problems with the Background Art When operating with such a conventional control system (
For example, when steam is injected into the combustor 3 (points B and G in FIG. 2), the turbine inlet pressure increases, so the compressor discharge (4) pressure PD also increases accordingly. That is, the exhaust gas temperature T2 moves from point G to point H. At this time, the turbine inlet temperature T is not at 6 points, but at 8 points 1r, and the temperature decreases slightly.

This is due to the following reasons. The general formula of the turbine is shown below.

K of one wipe is a specific heat ratio, and it decreases as moisture increases in the combustion gas, so when the inlet temperature T1 is constant, the exhaust gas temperature T2 increases. That is, when the inlet temperature T1 moves from point B to point 6 by performing steam injection, the exhaust gas temperature T2 does not move from point G to point H, but moves to point H.

However, the conventional control system does not allow operation at point H and must operate at point H and point E.

As described above, in the conventional control system, when steam injection is performed, the inlet temperature Tit must be lowered during operation, which has the disadvantage that the efficiency of the gas turbine is poor.

Purpose of the Invention The present invention has been made in consideration of the above circumstances, and provides a gas turbine control system that can operate the gas turbine without reducing its efficiency even if the combustion conditions such as the amount of steam injection change.
tt-O Object of the Invention 4a Summary To achieve this object, the present invention includes a detection device for detecting combustion conditions, and a method for correcting a turbine exhaust gas temperature curve 1lII based on a detection signal detected by the detection device. The turbine exhaust gas temperature curve is corrected by the correction device, and fuel control is performed according to the turbine exhaust gas temperature curve corrected by the correction device.

Embodiment of the Invention FIG. 3 shows a gas turbine control device according to an embodiment of the invention.

When steam injection is not performed, the measured temperature signal 13 of the gas turbine exhaust gas 12 is subtracted by the adder/subtractor 15 from the signal from the turbine exhaust gas temperature curve setter 14, and is input to the proportional integrator 16 to become the first fuel control signal 25a. On the other hand, the measured speed signal 17 and the speed setting signal 18 are subtracted by addition/subtraction Masuda to obtain a deviation signal. An adder/subtracter 21 adds the actual load signal 19 and the load deviation signal to obtain a deviation signal. This deviation signal is integrated by an integrator 22 and input to the addition/subtraction Masuda. The speed deviation signal is corrected by the load deviation signal in the adder/subtractor z3, and becomes the second fuel control signal 25b by the proportional calculator AO. 1st
A low value is selected for the fuel control signal 25a and the second fuel control signal 5b in the low value priority circuit section, and the fuel 7 is controlled by the fuel control valve 8 based on the selected fuel control signal.

When the control valve 10 injects the steam 9 into the combustor 3, the flow rate of the steam is detected by the flow meter 26 and input to the corrector n. The corrector section consists of a function generator side and four adders/subtractors. Based on the steam flow rate signal, the function generator outputs a predetermined correction signal, and this correction signal is added to the signal from the turbine exhaust gas temperature curve designer 14 in an adder/subtractor 29 .

In other words, the exhaust gas temperature curve has been corrected based on the steam flow rate signal.

Therefore, the turbine exhaust gas temperature T! -, as shown in Figure 2 (7
) At point H, it is possible to operate at a very high point, and the turbine entrance temperature can be set to 0 point instead of the T and iE point.
Even when steam injection is performed, the turbine inlet section 'a: T
It is possible to operate at a given temperature without lowering to I1. In other words, the gas turbine 2 can be operated at a location with high thermal efficiency, resulting in fuel savings.

In addition, in the first embodiment, the function setting device of the corrector 27:)B
Although the steam flow rate signal is rarely input to the controller, combustion conditions such as the exhaust gas signal of the turbine exhaust gas 12, the relative humidity signal of the atmosphere, and the type of fuel 7 may also be input to the function setting device 4 of the corrector 27. This allows more detailed corrections to be made in accordance with these combustion conditions.

When these examples are used in an exhaust heat recovery type combined cycle, the performance of the gas turbine itself can be improved, as well as
Since the temperature of the gas turbine exhaust gas increases, the output of the steam turbine can be increased, which has the advantage of improving the performance of the entire combined cycle brand.

Effect of the Invention (8) Since the present invention detects the combustion conditions as described above and corrects the turbine exhaust gas temperature curve based on this detection signal, the efficiency of the gas turbine is not reduced even if the combustion conditions change. It is possible to drive without having to worry about driving, and in the end, it has the effect of saving fuel.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a specific example of a gas turbine device to which a gas turbine control device according to the present invention is applied;
The figure is a graph showing the relationship between turbine inlet temperature, exhaust gas temperature, and pressure breather discharge pressure, and FIG. 3 is a block diagram of a gas turbine control device according to an embodiment of the present invention. 1...Compressor, 2...Gas turbine, 3...
・Combustor, 4... Driven machine, 5... Air, 6...
compressed air, 7... fuel, 8, 10... control valve, 9.
...Steam, 11...High temperature combustion gas, 12...Turbine exhaust gas, TI...Turbine population temperature, T,...Exhaust gas temperature, PD...Compressor discharge pressure, 13...
- Actual temperature signal, 14... Turbine exhaust gas temperature curve setting device, 15, 21, field, 29... Addition/subtraction device,
16...Proportional integrator, 17...Actually measured speed signal, 18
...Speed setting signal, 19...Actual load signal, addition...
Load command signal, z2... Integrator, Mu... Proportional calculator, 5... Low value priority circuit, 26... Flow meter, 27...
- Corrector, 4... Function generator, 5a... First fuel control signal, 25b... Second fuel control signal.

Claims (1)

[Scope of Claims] 1. A first fuel control signal according to a predetermined turbine exhaust gas temperature curve so that the turbine inlet temperature becomes a predetermined temperature, and a signal obtained by correcting a turbine speed deviation signal by a load deviation signal. A gas turbine control device that selects a second fuel control signal with a low value priority circuit and performs fuel control based on the selected fuel control signal, includes a detection device that detects a combustion condition and a detection signal that is detected. A gas turbine control device comprising: a correction device that corrects the turbine exhaust gas temperature curve based on the following. 2! P! f) The gas turbine control device according to claim 1, wherein the detection device for detecting combustion conditions is a flow meter for detecting the amount of steam injection. (1) -8