JPH03213626A - Control method for gas turbine - Google Patents

Abstract

PURPOSE:To carry out a warming-up operation most adequately by providing a temperature detector at a specific position of the turbine entrance position of a gas turbine, calculating a necessary worming-up operation time from the measurement of the temperature before the starting so as to set a temperature rising schedule, and thereby controlling the starting of the gas turbine. CONSTITUTION:To the turbine casing 1 of a gas turbine, a transition piece 2 to lead in a fuel gas is connected, and the first step stationary vane 3 is provided at the top of the transition piece 2, while the first step moving vane 4 is provided at the rear side of the stationary vane 3. In this case, an installing hole 8 is engraved to penetrate at a specific angle to the turbine casing 1 and an outer ring part 3a of the stationary vane 3, and a radiant thermometer sensor 9 is installed to the installing hole 8. The temperature of the ceramics cover of the front edge 5a of a moving vane 5 is measured by the sensor 9. And the temperature before the starting is detected in a gas turbine controller 12, and responding to a temperature rising schedule set depending on the calculation result, the starting of the gas turbine is controlled.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for controlling a gas turbine, and particularly to a method for controlling a gas turbine, and in particular, the present invention relates to a method for controlling a gas turbine. The present invention relates to a gas turbine control method.

(Prior Art) Generally, a gas turbine power generation plant incorporating a gas turbine as a turbomachine has a configuration as shown in FIG. Compressed air is supplied to the combustor 32, fuel is combusted in the lychee section 32g of the combustor 32, and the high-temperature combustion gas resulting from the combustion is passed through the transition piece 33 and the stationary blade 34 of the gas turbine to the rotor blade 35.
The rotor blades 35 are rotated to perform the work of the gas turbine 30.

In this type of gas turbine, it is known that increasing the turbine inlet temperature increases the thermal efficiency of the gas turbine, and in order to improve this thermal efficiency, ceramics with high heat resistance are used for the rotor blades in the gas turbine. A composite blade structure using the material for the outer cover has been proposed (Japanese Patent Application Laid-Open No. 1983-
(See Publication No. 119001). This composite blade structure has a relatively low-temperature implanted part made of a heat-resistant metal material, a ceramic material for the outer sheath that is exposed to high-temperature combustion gas, and a metal core with a specified strength. This is where the wing shaft section is placed.

FIG. 7 is a longitudinal cross-sectional view of a ceramic rotor blade composed of the ceramic outer sheath 40 and a metal blade shaft portion 41 as a mechanical member, where the metal blade shaft portion 41 is made of Ni-based alloy or the like. Made. This metal wing shaft portion includes an inner circumferential implant portion 41a that is implanted in the rotor, and a platform 41b that prevents high-temperature working gas (combustion gas) from entering the rotor side.
and a core portion 41 attached to the ceramic outer cover and outer surface.
, c, and a top cover 4 at the wing tip of the core part.
1a are integrally joined.

That is, this ceramic rotor blade has the above-mentioned metal blade shaft portion 4.
The ceramic outer cover 40 is inserted from the wing tip of the metal wing shaft 41, then the top cover 41d made of the same metal as the metal wing shaft 41 is attached, and then the core part 41c of the metal wing shaft 41 and the top cover 41d are attached. The joint surface A is pressurized in a high temperature atmosphere to form an integral joint structure.

By combining the ceramic sheath 40 with the metal wing shaft portion 41 in this manner, the characteristics of the ceramic material, which is strong against compressive stress and weak against tensile stress, can be utilized, and only compressive stress is applied to the ceramic sheath 40. As a result, the heat resistance, which is an inherent characteristic of ceramic materials, can be effectively exhibited. Furthermore, since the inner circumferential implanted portion 41a of the ceramic rotor blade is made of metal, it can withstand high tensile stress.

Note that a cooling passage (not shown) and a cooling air discharge hole communicating with the cooling passage are provided inside the ceramic rotor blade. Cooling air for cooling the rotor blades is convected inside this cooling passage, and this cooling air can be discharged to the outside from the cooling air discharge hole.

By the way, in the gas turbine 30 having the above-mentioned ceramic rotor blades, a difference in thermal elongation occurs between the ceramic jacket 40 and the top cover 41d when the gas turbine is started. It is known that the cause of this so-called difference in thermal expansion is the difference in linear expansion coefficient between the ceramic jacket 40 and the top cover 41d and the difference in temperature rise at startup.

The above thermal expansion difference can be relieved by slippage occurring at the contact surface between the ceramic jacket and the top cover when the rotational speed of the gas turbine is still low when the gas turbine is started. As the rotational speed of the gas turbine increases, the centrifugal force acting on the ceramic outer cover also increases, and the contact pressure between the ceramic outer cover and the top cover increases, preventing slippage as it would at low rotational speeds. This results in tensile stress being created in the ceramic envelope.

If this tensile stress exceeds the permissible tensile strength of the ceramic material, there is a risk of damage to the ceramic jacket.

Therefore, in order to prevent damage to the ceramic jacket, a control method has been proposed in which the slip is released when the gas turbine is started at a low rotational speed. This control method is intended to reduce the flow rate of air flowing into the combustor by blowing compressed air from an intermediate stage or discharge part of the compressor, thereby suppressing a rise in turbine inlet temperature. According to this method, the gas turbine is warmed up in a low rotational speed region for a certain period of time after ignition of the combustor, and the temperature of the ceramic outer cover and top cover is adjusted to the maximum difference in thermal expansion that can be released by sliding. By raising the temperature to near the upper limit temperature, it is possible to suppress an increase in the difference in thermal elongation that occurs thereafter.

This control method will be explained with reference to FIG. Figure 8 (a
), the solid line shows the temperature rise curve of the ceramic outer cover, the dashed-dotted line shows the temperature rise curve of the top cover,
Due to warm-up operation, the temperature of the ceramic outer cover and the temperature of the top cover rise to T1 along the respective set temperature rise curves.
．． The temperature is raised to 12°C. After that, the temperature is controlled according to a predetermined temperature increase schedule until the gas turbine reaches full load state. On the other hand, FIG. 8(b) shows an increasing characteristic curve of the amount of thermal elongation of the ceramic outer cover and the top cover corresponding to FIG. 8(a). In the figure, point A indicates the point in time when the thermal elongation difference Δε that can be released by sliding between the ceramic jacket and the top cover reaches the maximum value ΔεA. In other words, in the region from ignition to point A (hereinafter referred to as region I), the rotation speed of the gas turbine is low and the centrifugal force acting on the ceramic jacket is small, so there is a gap between the ceramic jacket and the top cover. The resulting frictional forces are also small and the ceramic envelope and top cover can slide freely.

On the other hand, in the area after point A (hereinafter referred to as area ■), the centrifugal force acting on the ceramic outer cover increases, and the frictional force generated between the ceramic outer cover and the top cover also increases. Since slippage between the outer cover and the top cover is inhibited, a situation arises in which the difference in thermal expansion cannot be relieved.

Therefore, in order to solve the above-mentioned problem, a temperature increase schedule as shown in FIG. method has been adopted. . In this control method, a warm-up operation is performed based on a set temperature increase schedule to raise the temperature of the ceramic outer cover and top cover to a predetermined temperature. According to this method, the thermal elongation difference Δε between the ceramic outer cover and the top cover becomes Δε0 as shown in FIG. 8(b) when warm-up is completed, and immediately after this, it becomes Δε9 at the above-mentioned point A. . Thereafter, even when full load operation is reached, the thermal elongation difference Δε increases only to ΔεB, which is approximately equal to Δε. Therefore, even after point A during operation, the frictional force generated between the ceramic jacket and the top cover almost increases, and excessive stress occurs as a result of inhibiting the sliding of the ceramic jacket. can be prevented.

(Problem to be Solved by the Invention) However, in the above-mentioned control method for starting a gas turbine, a warm-up operation is performed for a certain period of time to raise the ceramic jacket and top cover to a predetermined temperature. Therefore, there is a problem in that even if the gas turbine temperature is already high, the gas turbine must be warmed up for a longer time than necessary.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology, to grasp the temperature state of the rotor blades of a gas turbine using a thermometer, and to set a warm-up operation time and a temperature increase schedule according to the state. An object of the present invention is to provide a control method at the time of starting a gas turbine, which can be set to realize an optimal warm-up operation at the time of start-up according to the temperature state of the gas turbine.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a gas turbine with a rotor blade having a ceramic sheath coated on the outer surface of a metal blade shaft. A predetermined controlled warm-up operation is performed in several regions, and the temperature is raised to a temperature close to the temperature at which the amount of thermal expansion of the metal top cover can release the amount of thermal expansion of the ceramic outer cover,
In the gas turbine control method that prevents damage to the ceramic jacket by suppressing an increase in the difference in thermal expansion between the metal top cover and the ceramic jacket during subsequent operation, the turbine A temperature detection unit is installed at the rotor blade or near the rotor blade at the inlet position, measures the pre-start temperature at this position, calculates the required warm-up operation time according to this temperature state, and calculates the required warm-up operation time according to this temperature condition. The system is characterized in that a temperature increase schedule is set based on the temperature increase schedule, and the start-up control of the gas turbine is performed.

(Function) According to the present invention, a temperature detection unit is provided at the rotor blade or turbine inlet, the temperature before startup at this position is measured, and the temperature is increased based on the required warm-up operation time according to this temperature state. After setting the schedule and starting the gas turbine,
When starting up a gas turbine, when raising the ceramic outer cover and top cover of the rotor blades in the turbine to a predetermined temperature, the optimal warm-up operation time and temperature increase schedule can be set according to the temperature state of the turbine. Optimal warm-up operation can be performed based on this temperature increase schedule.

(Embodiment) An embodiment of the gas turbine control method according to the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is an enlarged view of the turbine inlet portion of a gas turbine. Reference numeral 1 in the figure indicates a turbine casing, and the turbine inlet of the turbine casing 1 has a transition section for introducing combustion gas. piece 2
is connected.

A first stage stator vane 3 is formed at the tip of this transition piece 2 . The outer ring portion 3a of the first stage stationary blade 3 is firmly held by a shroud 4 fixed to the inner surface of the turbine casing 1.

Furthermore, a first stage rotor blade 5 is arranged behind the first stage stationary blade 3. The root portion of the first stage rotor blade 5 is installed at the tip of the turbine rotor 6, and its structural shape is as shown in FIG. 7 already described.

A shroud 7 connected to the shroud 4 holding the first stage stationary blade 3 is provided on the inner surface of the turbine casing 1 facing the blade tip of the first stage rotor blade 5.

On the other hand, a mounting hole 8 is bored through the turbine casing 1 and the outer ring portion 3a of the first stage stationary blade 3 at a predetermined angle. A cylindrical radiation thermometer sensor 9 is fitted into the mounting hole 8 . A lens 10 is attached to the tip of the radiation thermometer sensor 9, so that the blade leading edge 5a of the first stage rotor blade 5 can be referenced. Further, this radiation thermometer sensor 9 is connected to a radiation thermometer main body 11, and this radiation thermometer main body 11 is connected to the ceramic of the blade leading edge 5a of the first stage rotor blade 5 measured by the radiation thermometer sensor 9. The temperature of the manufactured outer jacket can be continuously transmitted to the gas turbine control section 12. The gas turbine control unit 12 controls the inside of the turbine using a preset built-in function as shown in FIG. The optimum warm-up time can be set to raise the ceramic outer cover and top cover of the rotor blade to a predetermined temperature.

The temperature increase schedule during this optimal warm-up operation time was determined based on the temperature rise characteristic curve of the ceramic jacket and top cover and the increase characteristic curve of thermal elongation of the ceramic jacket and top cover shown in Figure 3. explain.

For example, as shown in Fig. 3(a), at the time of ignition, the gas turbine has already reached the gas turbine temperature To, which is close to the set temperature T1 and T when the ceramic jacket temperature and the top cover temperature are warmed up. It may be in a so-called hot state. At this time, during the warm-up operation, the gas turbine temperature is maintained at T within the warm-up time determined from FIG. This may be carried out based on a temperature increase schedule in which the temperature of the ceramic envelope and the temperature of the top cover are raised to the set temperatures T1 and T2.

As a result, in the hot state described above, the warm-up operation time can be reduced to approximately 1/2 compared to the temperature increase schedule shown in FIG. 8.

Note that the temperature increase schedule after the completion of warm-up operation at this time may be the same as that shown in Fig. 8, so that even when the gas turbine is in a hot state, the thermal expansion difference at point A can be reduced to Δε. Even after full-load operation, the thermal elongation difference Δε can be suppressed to ΔεB, which is approximately equal to Δε. As a result, the frictional force generated between the ceramic jacket and the top cover hardly increases, even when the gas turbine is in a hot state and startup control is performed using a temperature increase schedule that shortens the warm-up time.
It is possible to prevent excessive stress from being generated in the ceramic jacket.

As another example, it is also possible to measure the temperature of the metal top cover by using the above-mentioned radiation thermometer sensor as a reference to the metal top cover. According to this method, the distance between the radiation thermometer sensor and the metal top cover can be reduced, and the accuracy of temperature measurement can be improved. Also,
The temperature of both the ceramic shell and the metal top cover may be measured.

FIGS. 4 and 5 show another embodiment in which a thermocouple is used as the temperature measurement sensor instead of the radiation thermometer sensor. Figure 4 shows a thermocouple 13 attached to the ceramic outer sheath at the center portion 5b of the first stage rotor blade, with a total of 1i111.
The temperature signal can be transmitted to the gas turbine control section 12 via the slip ring 14. Moreover, FIG. 5 shows an arrangement in which the temperature of the wheel space 15 before and after the first stage rotor blade can be measured by a thermocouple 1B instead of directly measuring the temperature of the ceramic outer cover.

According to this measuring means, it is necessary to estimate the temperature of the ceramic outer cover or the metal top cover from the temperature of the wheel space 15 before processing in the gas turbine control unit 11, or the radiation thermometer. This method has the advantage that it does not require the use of such special measuring instruments, nor does it require any technology to securely attach the thermocouple to a ceramic jacket that rotates at high speed.

Furthermore, instead of using the built-in function shown in Figure 2, the relationship between the temperature of the ceramic jacket and the elapsed time after shutdown is determined from the temperature measurement results, and the relationship between the temperature of the ceramic jacket and the elapsed time after shutdown is determined from the temperature measurement results. A predetermined warm-up time can also be determined by measuring the elapsed time and estimating the temperature of the ceramic jacket from this elapsed time. According to this estimation means, it is possible to know the predetermined warm-up operation time without measuring the gas turbine temperature each time.

〔Effect of the invention〕

A temperature detection unit is provided at or near the rotor blade at the turbine inlet position of the gas turbine, and the temperature before startup is measured at this position,
The required warm-up operation time according to this temperature state is calculated, a temperature increase schedule is set based on this required warm-up operation time, and the startup control of the gas turbine is performed. It is possible to achieve the effect that an optimal warm-up operation can be performed according to the temperature state of the turbine.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an embodiment of the temperature measurement method for gas turbine start-up control according to the present invention, and Fig. 2 shows the relationship between the ceramic jacket temperature or the metal top cover temperature and the required warm-up time. A characteristic curve diagram showing an example of the relationship, FIG.
Figures 4 and 5 show the temperature increase characteristic curve of the outer cover made of wood and the top cover, the characteristic curve of increase in thermal elongation of the outer cover made of ceramic wood and the top cover, and Figures 4 and 5 show other implementations of the temperature measurement method according to the present invention. FIG. 6 is a cross-sectional view of a turbine inlet of a typical gas turbine, FIG. 7 is a cross-sectional view of an embodiment of the rotor blade of the present invention, and FIG. 8 is a conventional FIG. 3 is a diagram illustrating a temperature rise characteristic curve of the ceramic jacket and the top cover and an increase characteristic curve of the amount of thermal elongation of the ceramic jacket and the top cover when gas turbine startup control is performed. 3... 1st stage stationary blade, 5... 1st stage rotor blade, 9... Radiation thermometer sensor, 11... Radiation thermometer body, 12...
- Gas turbine control section, 13... thermocouple, 15... wheel space.

Claims (1)

[Scope of Claims] When starting up a gas turbine equipped with rotor blades in which a ceramic sheath is coated on the outer surface of a metal blade shaft, a predetermined controlled warm-up operation is performed in a low rotational speed region. The temperature is raised to a temperature close to the temperature at which the thermal elongation of the top cover can release the thermal elongation of the ceramic jacket, and in subsequent operations, the difference in thermal expansion between the metal top cover and the ceramic jacket increases. In a gas turbine control method that prevents damage to the ceramic outer sheath, a temperature detection unit is provided at or near the rotor blade at the inlet position of the turbine, and the temperature before startup is measured at this position. The gas turbine is characterized in that the required warm-up operation time is calculated according to this temperature state, a temperature increase schedule is set based on this required warm-up operation time, and startup control of the gas turbine is performed. control method.