JPH0457852B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention measures gas turbine compressor discharge air pressure and gas turbine exhaust gas temperature, and uses these measurements to control gas turbine combustion gas temperature. The present invention relates to a gas turbine combustion gas temperature control method and device.

[Background of the invention]

In a gas turbine control system, what ultimately determines the operating state of a single-shaft gas turbine in particular is the fuel flow rate.

FIG. 1 shows the components of a typical single-shaft gas turbine, and FIG. 2 shows a conceptual diagram of a typical gas turbine control.

The single-shaft gas turbine shown in FIG. It has a supply system, etc. In FIG. 1, IA indicates gas turbine compressor inlet air, EG indicates gas turbine exhaust gas, and F indicates fuel.

The gas turbine control system shown in FIG. 2 also includes a low value selector 7. The gas turbine control system shown in FIG. In addition, in Figure 2,
VCE indicates gas turbine control signal.

Elements that control the fuel flow rate supplied to the combustor 2 are the combustion gas or exhaust gas temperature and a startup control signal in a startup state, and the combustion gas or exhaust gas temperature and a speed control signal in a loaded state. . In gas turbines for power generators, the speed must be kept constant, so the fuel flow rate is controlled by speed control under partial load conditions. However, speed control alone cannot suppress the life consumption of gas turbine hot passage components due to the combustion gas temperature which inevitably increases when the load increases. Therefore, a certain upper limit value of gas turbine combustion gas temperature is set, and control is performed so as not to exceed that value. This is temperature control.

FIG. 3 shows a typical gas turbine state diagram.

In this Figure 3, S is entropy, I is enthalpy, W _C is compression work, F is fuel, W _T is gas turbine work, 8 is gas turbine compressor inlet, 9 is gas turbine compressor outlet, 10 indicates a gas turbine inlet, and 11 indicates a gas turbine outlet.

By the way, it is not technically impossible to directly measure the gas turbine inlet temperature (combustion gas temperature), but this combustion gas temperature exceeds 1000℃, and it is extremely difficult to accurately measure the true value. It is difficult to Furthermore, the combustion gas temperature distribution at the gas turbine inlet is not uniform. Therefore, it is necessary to indirectly measure the combustion gas temperature by other methods. A typical method is the gas turbine compressor discharge air pressure bias method. This method measures the gas turbine compressor discharge air pressure and the gas turbine exhaust gas temperature and calculates the combustion gas temperature.
Considering this based on the state diagram in Figure 3, we get
It can be seen that a certain relationship holds between the gas turbine compressor discharge air pressure, the gas turbine exhaust gas temperature, and the combustion gas temperature. Here, since the enthalpy I on the vertical axis in FIG. 3 is approximately proportional to temperature, the vertical axis can be considered to be temperature.

Fig. 4 shows the gas turbine state change diagram, and Fig. 5 shows the gas turbine state change diagram.
The figure shows the relationship between gas turbine compressor discharge air pressure, gas turbine exhaust gas temperature, and combustion gas temperature.

In addition, in FIG. 4, T indicates the temperature, T _F indicates the upper limit value of the combustion gas temperature, and other specifications are the same as in FIG. 3. Further, in FIG. 5, T _X indicates the gas turbine exhaust gas temperature, and P _CD indicates the gas turbine compressor discharge air pressure.

In FIG. 4, it is assumed that the gas turbine is operated at a certain upper temperature limit, that is, at a temperature of 8→9→10→11. Next, assume that due to some change in operating conditions, the gas turbine compressor discharge air pressure increases to 9'. At this time, if the fuel flow rate does not change,
8 → 9′ → 10″ → 11″, and the combustion gas temperature exceeds the upper limit. Therefore, if we reduce the fuel flow rate so that the combustion gas temperature reaches the 10' point, 8→
The shape is 9′→10′→11′. Now, under various operating conditions of the gas turbine (atmospheric temperature, load, etc.), the gas turbine compressor discharge air pressure P _CD , the gas turbine exhaust gas temperature T _X and the combustion gas temperature T _F
If you plot the relationship, it will look like Figure 5,
Finally, the combustion gas temperature can be calculated using the formula expressed as T _F =f(P _CD , T _X ). In this example, the gas turbine compressor discharge air pressure P _CD is 9′, and the gas turbine exhaust gas temperature _T
11', the calculated combustion gas temperature value exceeds the combustion gas upper limit value T _F , so the fuel flow rate is throttled and controlled to return to the combustion gas temperature upper limit value T _F.

FIG. 6 shows a typical conventional gas turbine combustion gas temperature control system.

In this control system, the gas turbine compressor discharge air pressure P _CD measured by an output detector (not shown) installed at the gas turbine compressor outlet is determined by the function unit 12 to be the gas turbine exhaust gas temperature. This becomes the control exhaust gas temperature signal _TX . On the other hand, assuming that the pressure detector is out of order, _the signal generator 14 outputs the control exhaust gas temperature upper limit signal T _XMAX , whichever is the lower value _of the control exhaust gas temperature signal T is selected by the low value selector 13, and the gas turbine exhaust gas temperature control value _TXL is output. On the other hand, a gas turbine exhaust gas temperature signal T _X1 measured by a plurality of temperature detectors (not shown) installed at the gas turbine exhaust port...
T _XN enters the intermediate value selector 15, and intermediate value T _XM is output. In addition, the temperature control value T _XL and the intermediate value
T _XM enters the comparator 17, and the difference is output,
The intermediate value T _XM from the proportional integrator 18 is the temperature control value T _XL
Gas turbine control signal VCE is output so that At this time, the temperature increase rate output by the temperature increase rate limiter 16 is also compared and controlled so as not to exceed the limit value.

This conventional gas turbine combustion gas temperature control system is advantageous in that control is simplified.

However, in the conventional gas turbine combustion gas temperature control system, as explained in FIG. 4, the enthalpy is approximated as being approximately proportional to the temperature. Changing impacts are not taken into account. This effect of relative humidity on enthalpy is caused by differences in the amount of water vapor contained in the atmosphere.

Figure 7 shows the influence of relative humidity at a certain combustion temperature.

_As can be seen from Figure 7, you can calculate _{T F} = _f (P _CD , _T Depending on the calculation, the combustion gas temperature will change. In other words, if the combustion gas temperature control calculator is programmed at a relative humidity of 0%, when the relative humidity is 100%, the combustion gas temperature will not be the same as when the relative humidity is 0% unless the gas turbine exhaust gas temperature is further increased by _ΔT First, the gas turbine exhaust gas temperature is controlled to be lower by ΔT _X. This causes the gas turbine to operate at lower output and efficiency than thermodynamically calculated output and efficiency. Conversely, if you program 100% relative humidity, the relative humidity will be 0.
%, the gas turbine is operated at temperatures exceeding the combustion gas temperature upper limit, resulting in a problem that the lifespan of gas turbine high-temperature passage components is greatly reduced.

[Purpose of the invention]

An object of the present invention is to provide a gas turbine combustion gas temperature control method that solves the problems of the prior art and can optimally control the gas turbine combustion gas temperature without impairing the simplicity of control. Another object of the present invention is to provide a gas turbine combustion gas temperature control device that can reliably implement the method described above.

[Summary of the invention]

The method of the present invention detects the gas turbine compressor inlet air relative humidity, uses this gas turbine compressor inlet air relative humidity to calculate the gas turbine exhaust gas temperature change due to the relative humidity change, and uses this calculated value as Add this value to the gas turbine exhaust gas control absolute value calculated using the gas turbine compressor discharge air pressure actual measurement value, use this value as the gas turbine exhaust gas control command value, compare it with the gas turbine exhaust gas temperature actual value, and calculate the difference. The feature is that the gas turbine combustion gas temperature is controlled to the set value regardless of the gas turbine compressor inlet relative humidity by minimizing The gas turbine combustion gas temperature can be optimally controlled without impairing performance.

In addition, the device of the present invention is provided with a first function unit that calculates and outputs an absolute value of gas turbine exhaust gas control from the measured value of gas turbine compressor discharge air pressure, and a relative humidity detector is installed at the gas turbine compressor inlet. At the same time, a second function receives an inlet air relative humidity signal of the gas turbine compressor from the relative humidity detector, and calculates and outputs a change in gas turbine exhaust gas temperature due to a change in relative humidity from the inlet air relative humidity. a gas turbine exhaust gas control absolute value output from the first function function unit and a second function function unit.
A gas turbine exhaust gas control command system including an adder that adds the gas turbine exhaust gas temperature change output from the function unit and outputs a gas turbine exhaust gas temperature control value is provided. The feature is that a comparator is installed that takes in the gas turbine exhaust gas temperature control value from the system, compares it with the actual turbine exhaust gas temperature value, and outputs the difference.With this configuration, the above method can be carried out reliably. can do.

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

FIG. 8 shows an example of a gas turbine combustion gas temperature control device for implementing the method of the present invention;
A pressure detector (not shown) installed at the gas turbine compressor outlet, a relative humidity detector (not shown) installed at the gas turbine compressor inlet, and multiple temperature sensors installed at the gas turbine outlet. a detector (not shown), a first function device 19 connected to the pressure sensor, a second function device 20 connected to the relative humidity sensor, and a signal generator that is activated when the pressure sensor fails. an intermediate value selector 15 connected to the temperature detector, a temperature rise rate limiter 16, an adder 21 connected to the first and second function units 19 and 20, and an intermediate value selector 15 connected to the temperature detector; a low value selector 22 connected to the generator 14 and the adder 21; and said intermediate value selector 1.
5, a temperature rise rate limiter 16, a comparator 17 connected to a low value selector 22, and a proportional integrator 18 connected to the comparator 17.

The first function unit 19 takes in the gas turbine compressor discharge air pressure signal P _CD from the pressure detector,
Gas turbine exhaust gas temperature signal at 0% relative humidity
It is designed to calculate and output T _XO .

The second function unit 20 receives the inlet air relative humidity signal of the gas turbine compressor from the relative humidity detector, calculates and outputs a gas turbine exhaust gas temperature change control signal ΔT _X at relative humidity %. It's summery.

The adder 21 takes in the gas turbine exhaust gas temperature signal _TXO from the first function unit 19 and takes in the gas turbine exhaust gas temperature change control signal ΔT _X from the second function unit 20, and both signals _TXO , _ΔT
is added to output the control exhaust gas temperature signal T _X at the relative humidity %.

The adder 21 and the low value selector 22 constitute a gas turbine exhaust gas control command system,
The low value selector 22 receives the relative humidity from the adder 21 as 0.
% control exhaust gas temperature signal T _X is taken in, and when the pressure detector fails, the control exhaust gas temperature upper limit signal _T
Select the lower value of either T _X or T _XMAX to obtain the gas turbine exhaust gas temperature control value _T
is configured to output the signal to the comparator 17.

Next, an example of the method of the present invention will be explained in relation to the operation of the gas turbine combustion gas temperature control device of the above embodiment.

The gas turbine compressor discharge air pressure P _CD measured by the pressure detector installed at the gas turbine compressor outlet is converted by the first function unit 19 to the control exhaust gas temperature signal T _XO at 0% relative humidity. Become. Further, the gas turbine compressor inlet air relative humidity signal measured by the relative humidity detector installed at the gas turbine compressor inlet is transmitted to the second function unit 20.
Therefore, the gas turbine exhaust gas temperature change control signal ΔT _X at relative humidity % is obtained. These signals T _XO ,
ΔT _X is added by an adder 21 and becomes the controlled exhaust gas temperature signal T _X at the relative humidity %. on the other hand,
Assuming a pressure detector accident, _the signal generator 14 outputs the controlled exhaust gas temperature upper limit signal T _XMAX , and lowers the lower value of either _the controlled exhaust gas temperature signal T Value selector 22
and outputs the gas turbine exhaust gas temperature control value _TXL at the relative humidity %. On the other hand, the gas turbine exhaust gas temperature signal measured by multiple temperature sensors installed in the gas turbine exhaust
T _X1 , . . . T _XN enter the intermediate value selector 15, and the intermediate value T _XM is output. The gas turbine exhaust gas temperature control value T _XL and the intermediate value T _XM of the gas turbine exhaust gas temperature enter the comparator 17, and this difference is output, and the intermediate value _T The gas turbine control signal VCE is output from the proportional integrator 18 so that the control value T _XL is reached.
is output, and the gas turbine exhaust gas temperature is controlled. At this time, the comparator 17 also compares the temperature rise rate output from the temperature rise rate limiter 16, and controls the temperature rise rate so as not to exceed the limit value.

Therefore, according to this embodiment, using the gas turbine compressor inlet air relative humidity detected by the relative humidity detector installed at the gas turbine compressor inlet, regardless of the atmospheric relative humidity, The gas turbine combustion gas temperature can be controlled to a set value. As a result, it is possible to prevent the combustion gas temperature from increasing more than necessary and consuming the life of the high-temperature gas passage components of the gas turbine, and conversely, it is possible to prevent the combustion gas temperature from being kept too low than necessary, which reduces the output of the gas turbine. It is possible to prevent a decrease in efficiency and a decrease in efficiency. Furthermore, it becomes possible to accurately control the _NOx value generated by the gas turbine to a predicted value.

〔Effect of the invention〕

According to the method of the present invention described above, the gas turbine compressor inlet air relative humidity is detected, and the gas turbine exhaust gas temperature change due to the relative humidity change is calculated using the gas turbine compressor inlet air relative humidity, This calculated value is added to the gas turbine exhaust gas control absolute value calculated using the gas turbine compressor discharge air pressure actual measurement value, and this value is used as the gas turbine exhaust gas temperature control value and is used as the gas turbine exhaust gas temperature actual measurement value. By comparing the differences and minimizing the difference, the gas turbine combustion gas temperature is controlled to the set value regardless of the gas turbine compressor inlet relative humidity, so the simplicity of control is reduced. Moreover, the gas turbine combustion gas temperature can be optimally controlled regardless of the inlet air relative humidity of the gas turbine compressor, and the gas turbine can be reliably controlled to the required output and efficiency. This has the effect of maintaining the life of the high-temperature gas passage components of the gas turbine, and the effect of accurately controlling the _NOx value generated from the gas turbine to a predicted value.

Further, according to the device of the present invention, a first function unit is provided that calculates and outputs an absolute value of gas turbine exhaust gas control from an actual measured value of gas turbine compressor discharge air pressure, and a relative humidity detector is installed at the inlet of the gas turbine compressor. and a second device that receives an inlet air relative humidity signal of the gas turbine compressor from the relative humidity detector, and calculates and outputs a change in gas turbine exhaust gas temperature due to a change in relative humidity from the inlet air relative humidity. A function unit is provided, which adds the gas turbine exhaust gas control absolute value output from the first function unit and the gas turbine exhaust gas temperature change output from the second function unit, and calculates the gas turbine exhaust gas temperature. A gas turbine exhaust gas control command system including an adder that outputs a control value is provided, and the gas turbine exhaust gas temperature control value is fetched from the gas turbine exhaust gas control command system, and the difference is calculated by comparing it with the actual measured value of the turbine exhaust gas temperature. Since a comparator is installed that outputs , there is an effect that the method of the present invention described above can be carried out reliably.

[Brief explanation of drawings]

Figure 1 is a diagram showing the components of a typical single-shaft gas turbine, Figure 2 is a typical gas turbine control conceptual diagram, Figure 3 is a typical gas turbine status diagram, and Figure 4 is a gas turbine Figure 5 is a state change diagram showing the relationship between gas turbine compressor discharge air pressure, gas turbine exhaust gas temperature and combustion gas temperature, and Figure 6 shows the conventional technology, which is a typical gas turbine combustion gas temperature control. FIG. 7 is a diagram showing the influence of relative humidity at a certain combustion temperature, and FIG. 8 is a diagram showing an example of a gas turbine combustion gas temperature control device implementing the method of the present invention. P _CD …Gas turbine compressor discharge air pressure signal,
T _XO ... Gas turbine exhaust gas temperature signal when the relative humidity is 0%, ... Gas turbine compressor inlet air relative humidity signal, ΔT _X ... Gas turbine exhaust gas temperature change control signal when the relative humidity is %, T _X ... Control exhaust gas temperature signal at relative humidity %, T _XL ... Gas turbine exhaust gas temperature control value, T _XM ... Intermediate value of gas turbine exhaust gas temperature, VCE... Gas turbine control signal, 14... Signal at pressure detector failure generator,
15... Intermediate value selector for gas turbine exhaust gas temperature (actual measurement value), 16... Temperature increase rate limiter, 17... Comparator for gas turbine exhaust gas temperature control value, intermediate value of gas turbine exhaust gas temperature, and temperature increase rate. , 18
...Proportional integrator for the output of the comparator, 19, 20...First and second function unit, 21...Adder for the output of the first and second function unit, 22...For the output of the adder and signal generator. Low value selector.

Claims (1)

[Scope of Claims] 1. A gas turbine combustion gas temperature control method that measures gas turbine compressor discharge air pressure and gas turbine exhaust gas temperature and controls gas turbine combustion gas temperature based on these measured values. The relative humidity of the gas turbine compressor inlet air is detected, the gas turbine exhaust gas temperature change due to the relative humidity change is calculated using this gas turbine compressor inlet air relative humidity, and this calculated value is used as the gas turbine compressor discharge air relative humidity. This value is added to the gas turbine exhaust gas control absolute value calculated using the actual pressure value, and this value is compared with the gas turbine exhaust gas temperature actual value as the gas turbine exhaust gas temperature control value, and the difference is minimized. Therefore, a gas turbine combustion gas temperature control method is characterized in that the gas turbine combustion gas temperature is controlled to a set value regardless of the gas turbine compressor inlet relative humidity. 2. In a gas turbine combustion gas temperature control device that measures gas turbine compressor discharge air pressure and gas turbine exhaust gas temperature and controls gas turbine combustion gas temperature based on these measured values, the gas turbine compressor discharge air A first function unit is provided that calculates and outputs an absolute value for gas turbine exhaust gas temperature control from the actual measured pressure value, and a relative humidity detector is installed at the inlet of the gas turbine compressor. A second function unit is provided which takes in an inlet air relative humidity signal of the engine and calculates and outputs a change in gas turbine exhaust gas temperature due to a change in relative humidity from the inlet air relative humidity, and outputs the result from the first function unit. gas turbine exhaust gas control including an adder that adds the gas turbine exhaust gas control absolute value to the gas turbine exhaust gas temperature change output from the second function unit and outputs the gas turbine exhaust gas temperature control value. A command system is provided, and a comparator is installed that receives a gas turbine exhaust gas temperature control value from the gas turbine exhaust gas control command system, compares it with an actual gas turbine exhaust gas temperature value, and outputs the difference. Gas turbine combustion gas temperature control device.