JPS60247014A - Method of controlling temperature of combustion gas of gas turbine and device therefor - Google Patents

Abstract

PURPOSE:To aim at optimizing the control of temperature of combustion gas of a gas turbine, by computing a variation in the temperature of exhaust gas due to a variation in the relative humidity of air at the inlet of a gas turbine compressor to compensate the instruction value of exhaust gas temperature control. CONSTITUTION:The relative humidity of air at the inlet of a gas turbine compressor is detected and is transmitted to a second function unit 20 which computes and delivers an exhaust gas temperature change control signal DELTATX upon the relative humidity being phi. An adder adds DELTATX to an exhaust gas temperature signal TX0 which is obtained from a first function unit 19 when the relative humidity is zero, and delivers an exhaust gas temperature control signal TX upon the relative humidity being phi%. A comparator 17 compares this control signal with an exhaust gas temperature signal TXM from an intermediate value selector 15 to control the supply amount of fuel. With this arrangement the temperature of combustion gas is controlled to be optimum irrespective of the relative humidity of air at the inlet of the gas turbine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention is directed to a gas turbine which measures gas turbine compressor discharge air pressure and gas turbine exhaust gas temperature and uses these measured values to control gas turbine combustion gas temperature. The present invention relates to a 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 -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 the table and FIG. 2, ■CE indicates the 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 the startup control signal in the starting state, and the combustion gas or exhaust gas temperature and the speed control signal in the 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 FIG. 3, S is entropy, ■ is enthalpy, Wc is compression work, F is fuel, and WT is gas turbine work, 8 is gas turbine compressor inlet, 9 is gas turbine compressor outlet, and 10 is gas turbine compressor inlet. A gas turbine inlet is shown, and 11 is 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 100OC, and it is extremely difficult to accurately measure the true value. Have difficulty. Furthermore, the combustion gas temperature distribution at the gas turbine inlet is not uniform. Therefore, it is necessary to measure the combustion gas temperature indirectly 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 shown in FIG. 3, it can be seen that a certain relationship is established between the gas turbine compressor discharge air pressure, the gas turbine exhaust gas temperature, and the combustion gas temperature. Here, since the enthalpy (2) on the vertical axis in FIG. 3 is approximately proportional to the temperature, the vertical axis can be considered to be the temperature.

FIG. 4 shows a gas turbine state change diagram, and FIG. 5 shows the relationship among gas turbine compressor discharge air pressure, gas turbine exhaust gas temperature, and combustion gas temperature.

In FIG. 4, T indicates the temperature, TF indicates the upper limit value of the combustion gas temperature, and other specifications are the same as in FIG. 3.

In addition, in Fig. 5, Tx is the gas turbine exhaust gas temperature, P
cD indicates gas turbine compressor discharge air pressure.

In FIG. 4, it is assumed that the gas turbine is operated at a certain upper temperature limit and with the wheels 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' → Work 0" → Work 1"
Unfortunately, the combustion gas temperature exceeds the upper limit. Therefore, if the fuel flow rate is reduced so that the combustion gas temperature reaches the 10' point, the shape becomes 8→9'→10'→11'.

Now, various operating conditions of the gas turbine (atmospheric temperature.

When the relationship between gas turbine compressor discharge air pressure PCD% gas turbine exhaust gas temperature Tx and combustion gas temperature Ty is plotted at load 2, etc.), it becomes as shown in Fig. 5, and finally, T r = f The combustion gas temperature can be calculated using the formula expressed as (Pea, Tx). In this example,
If the gas turbine compressor discharge air pressure Pea is 9' and the gas turbine exhaust gas temperature Tx is 11', the calculated combustion gas temperature value exceeds the combustion gas upper limit Ty.
Control is performed to reduce the fuel flow rate and return the combustion gas temperature to the upper limit value TF.

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

In this control system, the gas turbine compressor discharge air pressure PcD measured by an output detector (not shown) installed at the gas turbine compressor outlet is controlled by the function unit 12 to be the gas turbine exhaust gas temperature. Exhaust gas temperature signal Tx
becomes. 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 TxMI, and selects which of the control exhaust gas temperature signal Tx and the control exhaust gas temperature upper limit signal TxYMX. or a lower value is selected by the low value selector 13, and the gas turbine exhaust gas temperature control value T'XL is selected.
Output. On the other hand, the gas turbine exhaust gas source If M T x s is measured by a plurality of temperature sensors (not shown) installed at the gas turbine exhaust port.
-TXN enters the intermediate value selector 15, and intermediate value TxM is output. Furthermore, the temperature control value TXL and the intermediate value TXM
is input to the comparator 17, the difference thereof is output, and the proportional integrator 18 outputs the intermediate value T x yiE temperature control value Txx.

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, so in reality, The effect of changing enthalpy is not taken into account. This effect of relative humidity on enthalpy often occurs due to 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 this Figure 7, assuming the relative humidity is 0%, T
Calculate F = f (Pen, Tx) or TF = f (Pen. with relative humidity as 100%).

The combustion gas temperature changes depending on whether Tx) is calculated. In other words, when the combustion gas temperature control calculator is programmed with relative humidity θ%, when the relative humidity is 100%, the combustion gas temperature will not be the same as the relative humidity θ% unless the gas turbine exhaust gas temperature is further increased by ΔTx. ,Δ
This is because the gas turbine exhaust gas temperature is controlled to be lower by Tx. This results in the gas turbine being operated at a lower output and efficiency than thermodynamically calculated. On the other hand, if the relative humidity is programmed at 100%, the gas turbine will be operated at temperatures exceeding the combustion gas temperature upper limit when the relative humidity is 0%, resulting in a problem that the life of the gas turbine high-temperature passage components will be 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. This system is characterized by the fact that the gas turbine combustion gas temperature is controlled to the set value 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 pressure assembly machine discharge air pressure, and a relative humidity detector is installed at the inlet of the gas turbine compressor. At the same time, the device receives the inlet air relative humidity signal of the gas turbine compressor from the relative humidity detector, and calculates and outputs the gas turbine exhaust gas temperature change due to the relative humidity change from the inlet air relative humidity. A second function unit is provided, and the gas turbine exhaust gas control absolute value output from the first function unit is added to the gas turbine exhaust gas temperature change output from the second function unit, and the gas turbine exhaust gas A gas turbine exhaust gas control command system including an adder that outputs a temperature control value is provided, and the gas turbine exhaust gas temperature control value is inputted from the gas turbine exhaust gas control command system and compared with an actual measured value of the turbine exhaust gas temperature. The method is characterized in that it is equipped with a comparator that outputs the difference between the two.With this configuration, the method described above can be carried out reliably.

[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, in which a pressure detector (not shown) installed at the outlet of the gas turbine compressor and a pressure detector (not shown) installed at the gas turbine compressor outlet are used. A relative humidity detector (not shown) installed at the inlet, a plurality of temperature detectors (not shown) installed at the gas turbine outlet, and a first function unit 19 connected to the pressure detector. and a second connected to a relative humidity detector.
a function unit 20, a signal generator 14 that operates when the pressure sensor fails, and an intermediate value selector 1 connected to the temperature sensor.
5, a temperature rise rate limiter 16, and the first. an adder 21 connected to the second function unit 19, 20, a low value selector 22 connected to the signal generator 14 and the adder 21, the intermediate value selector 15 and the temperature rise rate limiter 16; and a comparator 17 connected to the low value selector 22, and a proportional integrator 18 connected to the comparator 17.

The first function unit 19 receives the gas turbine compressor discharge air pressure signal Pen from the pressure detector, and sets the relative humidity to 0.
% of the gas turbine exhaust gas setting signal T x o is calculated and output.

The second function unit 2o receives the inlet air relative humidity signal ψ of the gas turbine compressor from the relative humidity detector, and generates a gas turbine exhaust gas temperature change control signal Δ at relative humidity ψ%.
It is designed to calculate and output Tx.

The adder 21 receives the gas turbine exhaust gas temperature signal '['xo from the first function unit 19 and receives the gas turbine exhaust gas temperature change control signal Δ from the second function unit 20.
Tx and both signals Txo.

The control exhaust gas temperature signal Tx at the relative humidity ψ% is output by adding ΔTx.

The adder 21 and the low value selector 22 constitute a gas turbine exhaust gas control command system, and the low value selector 22 receives the control exhaust gas temperature signal Tx at a relative humidity of 0% from the adder 21. Also, when the pressure detector fails, the control exhaust gas temperature upper limit signal TXMAX is input from the signal generator 14, and the lower value of both signals Tx and TXMIX is selected, and the gas turbine at the relative humidity ψ% is It is configured to output the exhaust gas temperature control value TXL 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 POD measured by a pressure sensor installed at the gas turbine compressor outlet is transmitted to the first function unit 19 and becomes a controlled exhaust gas temperature signal Txo at relative humidity θ%.・Also, the inlet air relative humidity signal ψ of the gas turbine compressor measured by the relative humidity detector installed at the gas turbine compressor inlet is determined by the second function unit 20, which is the gas at the humidity ψ% This becomes the turbine exhaust gas temperature change control signal ΔTx. These signals Txo
+ΔTx is added by an adder 21 and the relative humidity ψ%
This becomes the controlled exhaust gas temperature signal Tx at the time. On the other hand, assuming a pressure sensor accident, a multi-control exhaust gas temperature upper limit signal TXMAX is output to the signal generator 14, and the lower value of either the control exhaust gas temperature signal Tx or the control exhaust gas temperature upper limit signal TXMAX is output. The relative humidity ψ is selected by the low value selector 22.
Outputs the gas turbine exhaust gas temperature control value TXL at %. On the other hand, the gas turbine exhaust gas temperature signal TX1. measured by a plurality of temperature sensors installed in the gas turbine exhaust gas. ...TXN is input to the intermediate value selector 15, and the intermediate value TXM is output. The gas turbine exhaust gas temperature control value TXL and the intermediate value TXM of the gas turbine exhaust gas temperature enter a comparator 17, and the difference therebetween is output.
Proportional integrator 1 so that the intermediate value TXM of the gas turbine exhaust gas temperature becomes the gas turbine exhaust gas temperature control value TXL.
A gas turbine control signal VCE is output from 8 to control the gas turbine exhaust gas temperature. 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, the gas turbine compressor inlet air relative humidity detected by the relative humidity detector installed at the gas turbine compressor inlet is used to calculate the air relative humidity 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, the N generated by the gas turbine
The Ox value can also be accurately controlled to the expected 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 controlled using the gas turbine compressor inlet air relative humidity. By adding this value to the absolute value, using this value as the gas turbine exhaust gas temperature control value, and comparing it with the actual gas turbine exhaust gas temperature measurement value, and minimizing the difference, regardless of the gas turbine compressor inlet relative humidity, Since the gas turbine combustion gas temperature is controlled to the set value, the gas turbine combustion gas temperature can be optimized without compromising control simplicity and regardless of the gas turbine compressor inlet air relative humidity. NOx generated from gas turbines has the effect of controlling and, in turn, reliably controlling the required output and efficiency of the gas turbine, and maintaining the life of the high-temperature gas path components of the gas turbine. This has the effect of accurately controlling the value to the expected 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. At the same time, it receives an inlet air relative humidity signal of the gas turbine compressor from this relative humidity detector, and calculates and outputs the gas turbine exhaust gas temperature change due to the relative humidity change from the inlet air relative humidity. A second function unit is provided to add 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 A gas turbine exhaust gas control command system including an adder that outputs a gas temperature control value is provided, and the gas turbine exhaust gas temperature control value is input from the gas turbine exhaust gas control command system and compared with the actual measured value of the turbine exhaust gas temperature. Since a comparator is installed to output the difference between the two, the method of the present invention 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. Figure 7 is a diagram showing the system, Figure 7 is a diagram showing the influence of relative humidity at a certain combustion temperature, Figure 8 is
The figure shows an example of a gas turbine combustion gas temperature control device that implements the method of the present invention. Pen...Gas turbine compressor discharge air pressure signal, T
xo...Gas turbine exhaust gas temperature signal when the relative humidity is θ%, ψ...Gas turbine compressor inlet air relative humidity signal, ΔTx...Gas turbine exhaust gas temperature change when the relative humidity is ψ% Control signal, TI... Controlled exhaust gas temperature signal at relative humidity ψ%, Txt,... Gas turbine exhaust gas temperature control value, TxM... Intermediate value of gas turbine exhaust gas temperature, ■CE... gas turbine control signal,
14...Signal generator in case of pressure detector failure, 15...
Intermediate value selector for gas turbine exhaust gas temperature (actual value),
16...Temperature rise rate limiter, 17...Comparator for gas turbine exhaust gas temperature control value, intermediate value of gas turbine exhaust gas temperature, and temperature rise rate, 18...Proportional integrator for output of comparator , 19.20... 1st ° 2nd function unit, 21
...First. an adder for the output of the second function unit, 22...
Low value selector for adder and signal generator outputs. Agent Patent Attorney Masami Akimoto No. 10 Mo 7 Hanging 3 Mi 5 G Yu (+ Figure No. 50 Ding X Haku 6 Senman q Mouth X

Claims (1)

[Claims] 1. Gas turbine pressure! In a gas turbine combustion gas temperature control method that measures the I machine discharge air pressure and gas turbine exhaust gas temperature and controls the gas turbine combustion gas temperature based on these measured values, the gas turbine compressor inlet air relative humidity is detected. Then, using this gas turbine compressor inlet air relative humidity, the gas turbine exhaust gas temperature change due to the relative humidity change is calculated, and this calculated value is calculated using the gas turbine compressor discharge air pressure actual measurement value. By adding this value to the gas turbine exhaust gas control absolute value, comparing this value with the gas turbine exhaust gas temperature actual value as the gas turbine exhaust gas temperature control value, and minimizing the difference,
A gas turbine combustion gas temperature control method comprising controlling the gas turbine combustion gas temperature 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 A first function unit is provided that calculates and outputs the gas turbine exhaust gas control absolute value from the measured air 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 gas turbine exhaust gas temperature change due to a relative humidity change from the inlet air relative humidity, and the first function unit A gas turbine exhaust gas turbine including an adder that adds the gas turbine exhaust gas control absolute value outputted from the second function unit and the gas turbine exhaust gas temperature change amount outputted from the second function unit and outputs the gas turbine exhaust gas temperature control value. A gas control command system is provided, and a comparator is installed to take in the gas turbine exhaust gas temperature control value from the gas turbine exhaust gas control command system, compare it with the actual measured value of the turbine exhaust gas temperature, and output the difference. Gas turbine combustion gas temperature control device.