JPS61286537A - Gas turbine exhaust temperature control method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to water or steam injection type gas turbine control. This invention relates to nine gas turbine control methods characterized by accurately predicting combustor temperature.

[Background of the invention]

The output of a gas turbine increases as the combustion gas temperature increases, but due to the resistance of high-temperature components (combustor, turbine rotor, stationary blades) to high-temperature combustion gas, if the combustion gas temperature exceeds a certain tolerance value, , the lifespan of high-temperature components decreases to a level π that cannot be used for practical purposes. Therefore, the maximum output of the gas turbine can be controlled using the maximum (allowable) temperature of the combustion gas, but even if the combustion gas temperature is directly measured, the distribution of the combustion gas temperature at the measuring part will vary widely (generally 100
C), it is difficult to measure the average combustion temperature. In conventional technology, this maximum temperature control involves detecting the turbine exhaust temperature and compressor discharge pressure, indirectly determining the combustion gas temperature, and controlling the output when the permissible value is reached. ing.

On the other hand, water (or steam) injection type gas turbines, which inject water or steam into the combustor, have recently been put into practical use as a measure against pollution (e.g. NOx emission regulations) or to increase output. Since the one-way production system is the same as the conventional system, the following problem arises.

Figure 5 shows the main equipment configuration of the gas turbine power plant.

The air flowing in from the atmosphere is compressed by a compressor IVc and led to a combustor 2vc. Here, the flow rate guided through the fuel regulating valve 6 is ignited and combusted.

Water (or steam) added due to pollution regulations, etc. is guided to the combustor 6VC via the water (steam) injection regulating valve 7, expanded by the turbine 3, and this energy is transmitted to the directly connected generator 4, which generates electricity. It is converted into energy and transmitted to the grid via the circuit breaker 5. Furthermore, an overview of gas turbine control is shown in FIG. Control consists of a startup side that controls the gas turbine from startup to rated speed, a speed/negative control that controls during load operation, and a control system that controls the gas turbine so that it operates within the combustion gas temperature tolerance range. The fuel regulating valve 6 is controlled through a control mode switch that selects the three control modes.

Next, FIG. 7 shows the thermodynamic cycle of the gas turbine. The inhaled air is compressed and rises.
Move to. The gas that explodes in the combustor becomes high-temperature, high-pressure gas and moves to ■, and the gas expanded in the turbine is exhausted in ■. Therefore, the amount of transition from ■ to ■ is the amount of work (output) of the gas turbine, and the output increases as the allowable combustion temperature T3 increases. At this time, the intake air (atmosphere) temperature is A
As →B →C decreases, the amount of transition (output) from ■ to ■ increases.

Next, FIG. 8 shows the relationship between compressor discharge pressure P2 and exhaust temperature setting T4g according to the prior art. Since the thermodynamic cycle of the gas turbine changes depending on the intake air temperature, the permissible combustion temperature T is determined by detecting atmospheric changes in the compressor discharge pressure as a parameter.

The ratio of the exhaust gas temperature T4 determined in FIG. 7 is shown in the l/rJB diagram, assuming that T4 is constant. Therefore, in the exhaust gas temperature control shown in FIG. 6, the exhaust temperature is set with respect to the compressor discharge pressure p (see FIG. 8) and controlled so as not to exceed this temperature.

FIGS. 9 and 10 show changes in compressor discharge pressure and exhaust temperature at the maximum allowable combustion gas temperature when the amount of water (or steam) injected is gradually increased.

In Fig. 9, when the water (or steam) injection amount is increased as ■→＠→O when the atmospheric temperature is B, the compressor discharge pressure P!が■′→＠
'→θ', and the exhaust temperature T4 increases as '→σ'→
It descends like a'. This is because the water injected into the combustor is vaporized and mixed with the combustion gas, resulting in an increase in the combustion gas flow rate and an increase in the discharge pressure (■'→■'→θ' ) by bringing about. ■', o/, θ' and σ, α', θ'' obtained in atmosphere B
The points in Figure 8 are applied to Figure 8, and in the same way, each point in the case of atmospheric temperature human and B is applied to Figure 8 VC.
This is figure 0.

According to Figure 10, the water (or steam) injection amount is ■→＠→θ
When the temperature increases, the exhaust temperature setting temperature T4s&';t becomes higher.

In conventional exhaust temperature control, when there is no water (or steam) flow rate, for example, if you set ■, even if the water (or steam) injection amount is @ or O, the ■ control line Even though it is controlled, there is a drawback that the fUC1 fuel that reaches the maximum combustion temperature of the gas turbine is suppressed.

[Purpose of the invention]

An object of the present invention is to provide a control method that accurately predicts combustor gas temperature and increases the output of a gas turbine regardless of the amount of water (or steam) injected.

[Summary of the invention]

The key point of the present invention is that when water (or steam) is injected, the discharge pressure increases, so in order to prevent a drop in maximum output due to an apparent increase in combustor gas temperature, the water (or steam) injection amount and inlet The purpose is to calculate the combustor gas temperature by correcting the discharge pressure depending on the ratio to the air amount or the ratio between the water (or steam) flow rate and the fuel flow rate.

[Embodiments of the invention]

In the present invention, the conventional exhaust gas temperature and pressure are corrected using the water (or steam) injection flow rate as a parameter, and the maximum allowable combustion gas temperature is calculated. An embodiment of the side leg system that enables output operation will be described based on FIG. 1.

The signal MW detected by the air flow rate detector 8 and the signal MA detected by the water (or steam) injection flow rate detector 11 are calculated by the calculator 12, and the signal MW detected by the compressor discharge pressure detector 9 is calculated. A calculation unit 13 calculates f (pt) for the signal P, and a multiplier 14 corrects the compressed material discharge pressure signal and uses it as a set value. Further, the signal detected by the exhaust temperature detector 10 is fed back by the adder 12, and is used by the proportional integral calculator 16 as a control signal for the fuel flow rate regulating valve.

At this time, a control characteristic diagram of the output signal A (set value) of the multiplier 14 and the feedback signal is shown in FIG. Compressor discharge pressure P.

For, water (or steam) injection flow rate MW and air flow rate MA
By correcting the ratio with bias, water (
Even if the compressor discharge pressure increases due to an increase in the injection flow rate (or steam), the exhaust temperature setting T41 remains high in accordance with the ratio, making it possible to control the maximum output.

Further, as shown in FIG. 3, as correction parameters, the water (or steam) injection flow rate MW and the signal MP detected by the fuel flow rate detector 17 are calculated in the calculator 18, and the compressor discharge is adjusted. Maximum output control is also possible by correcting the pressure P.

At this time, a control characteristic diagram of the output signal B (set value) of the multiplier 14 and the feedback signal is shown in FIG.

〔Effect of the invention〕

According to the present invention, regardless of the water (or steam) injection amount,
Since the combustion degree is the maximum allowable value, the maximum output of the gas turbine can be extracted.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing a first embodiment of the present invention;
Fig. 2 is a supplementary explanatory diagram showing the control characteristics of Fig. 1, Fig. 3 is a control block diagram showing a second embodiment of the present invention, and Fig. 4 is a supplementary explanatory diagram showing the side leg percentage characteristics of Fig. 3. Figure 5 is a diagram of the main equipment configuration of a gas turbine power plant, Figure Wc6 is a schematic diagram of gas turbine control, Figure 7 is an explanatory diagram of the thermodynamic cycle of the gas turbine, and Figure 8 is a diagram of the conventional exhaust temperature. The control diagram, FIG. 9 is a control diagram when the atmospheric temperature changes in the conventional exhaust temperature side leg, and FIG. 10 is a supplementary explanatory diagram of FIG. 5. 8...Air flow rate detector, 9...Compressor discharge pressure detector, 10...Exhaust temperature detector, 11...Water (steam)
Injection flow rate detector, 12.13... Arithmetic unit, 14...
Multiplier, No. 30 50 Enthalpy (S) Figure 8 Compression pressure (Px) Certain Figure 9 Enthalpy (S)

Claims (1)

[Claims] 1. In a gas turbine equipped with a device for injecting water or steam into the combustor, the set value of the exhaust temperature for indirectly controlling the combustion concentration is made a function of the flow rate of water or steam. A gas turbine exhaust temperature control method characterized by: 2. A gas turbine exhaust temperature control method according to claim 1, characterized in that the ratio of the water or steam flow rate to the compressor inlet air flow rate is used as a parameter as a function of the water or steam flow rate. 3. A gas turbine exhaust temperature control method according to claim 1, characterized in that the ratio of the water or steam flow rate to the fuel flow rate is used as a parameter as a function of the water or steam flow rate.