JPH05202702A - Casing exhaust chamber cooling device of steam turbine - Google Patents

Abstract

PURPOSE:To operate a steam turbine power generating facility with a low load continuously so as to improve reliability of a turbine apparatus. CONSTITUTION:In the casing exhaust chamber cooling device 16 of a steam turbine 10, a spray device 17 for cooling an exhaust range and a spray device 18 for cooling a turn-up range are respectively provided in the casing exhaust chamber 15 of the steam turbine 10. When the steam turbine 10 is operated with a low load, only spray device 17 for cooling the exhaust range is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine power generation facility capable of continuous operation under a low load, and more particularly to a casing exhaust chamber cooling device for a steam turbine provided in the steam turbine power generation facility.

[0002]

2. Description of the Related Art In recent years, as the number of nuclear power plants that are constantly operated at full power has increased, the thermal power plants have been operating in the middle. There is a situation that must be met.

By the way, when the thermal power plant is operated under a low load, as the turbine load of the steam turbine decreases, the windage loss at the final stage rotor blades increases, and the turbine exhaust temperature rises due to the increase in the windage loss. When the turbine exhaust temperature rises, the steam turbine may have a serious adverse effect on the reliability of turbine equipment, such as misalignment due to thermal deformation of the turbine casing and damage to the blade due to the reduction in material strength of the turbine last stage blade. There is a nature.

FIG. 5 shows an example of the relationship between the turbine load and the turbine exhaust temperature when the seawater temperature is constant in the steam turbine power plant.

When the turbine exhaust gas is operated in a load zone below the turbine load where the turbine exhaust gas enters the superheat region above the saturation temperature (saturation line 1), the turbine exhaust gas temperature rises sharply as shown by the turbine exhaust temperature characteristic curve 2. For example, in the 15% turbine load operation, the turbine exhaust temperature reaches a high temperature as shown at point e (for example, 115 ° C.) in FIG.

On the other hand, in order to maintain the reliability of the turbine equipment of the steam turbine power plant, a temperature limitation value is usually set to the turbine equipment which is affected by the turbine exhaust, and this limitation temperature is monitored by the turbine exhaust temperature. Specifically, in order to prevent thermal deformation of the steam turbine, the temperature of the outer casing of the low pressure casing exhaust chamber is set to the limit temperature a shown in FIG.
(For example, 80 ° C. to 100 ° C.) or less, or the temperature of the final stage moving blade is limited to a limiting temperature b (for example, 180 ° C. to 250 ° C.) in order to prevent deterioration of the material strength of the turbine final stage moving blade.
C., b> a) or less.

In the steam turbine power plant, it is necessary to cool the outer casing of the steam turbine and the final stage moving blades in order to keep the temperature limit value of the turbine equipment. For this cooling, a casing exhaust chamber cooling device is provided. ing.

A conventional casing exhaust chamber cooling device for a steam turbine is constructed as shown in FIGS. 6 and 7, and the casing exhaust chamber cooling device 3 defines an external casing 5 defining a low pressure casing exhaust chamber 4 and The turbine last stage rotor blade 6 is being cooled.

The casing exhaust chamber cooling device 3 of the steam turbine is provided with a spray device 7 having a spray nozzle 7a in the low pressure casing exhaust chamber 4, and the spray device 7 supplies water to the spray nozzle 7a through a spray pipe 7b. It is connected to the pipe 7c. The spray pipe 7b is provided with a spray valve 7d, and the spray valve 7d has a turbine exhaust temperature of the low pressure casing exhaust chamber 4 which is equal to or higher than a spray set temperature c (for example, 60 ° C. to 80 ° C., c> a) shown in FIG. Will be opened when is reached. The turbine exhaust temperature is detected by a thermocouple 9 provided near the tip of the turbine last stage rotor blade 6 of the inner casing 8.

By opening the spray valve 7d, spray water is sprayed (injected) into the low-pressure casing exhaust chamber 4 from the spray nozzle 7a at a wide angle, and the casing exhaust chamber 4 is cooled. As a result, the outer casing 5 and the final stage of turbine operation. The blade 6 is being cooled.

By the way, in the conventional casing exhaust chamber cooling device 3, the spray nozzle 7a of the spray device 7 is used.
The spray water from is sprayed over almost the entire area of the low pressure casing exhaust chamber 4. This low-pressure casing exhaust chamber 4 has an exhaust region 4 which is affected by the behavior of the flow of spray water sprayed.
a and turn-up area 4b. The turn-up region 4b is a region in which the working steam and the drain flow backward, and there is a possibility that the flow toward the final stage rotor blade 6 of the turbine may occur.

During low-load operation of the steam turbine, there may be a negative degree of reaction (a pressure higher at the rotor blade outlet than at the rotor blade inlet) near the turbine last stage rotor blade. When the reaction degree is reached, a part of the spray water in the turn-up area 4b is caught in the final stage moving blade 6 and cools this moving blade 6.

Therefore, among the spray water sprayed from the spray device 7 of the casing exhaust chamber cooling device 3 to the low pressure casing exhaust chamber 4, the spray water sprayed to the exhaust region 4a contributes to the cooling of the outer casing 5 as it is. Also, a part of the spray water sprayed in the turn-up region 4b is caught in the turbine last stage rotor blade 6 and contributes to the cooling of the rotor blade 6. Most of the spray water sprayed in the turn-up region 4b is carried on the working steam flow working in the steam turbine and flows out to the exhaust region 4a.

[0014]

In the conventional casing exhaust chamber cooling device for a steam turbine, the turn-up region 4b from the spray device 7 is operated during low load operation of the steam turbine.
Part of the spray water sprayed on the turbine is the turbine final stage rotor blade 6
When entrained in the water, the liquid having a large particle diameter contained in the spray water collides with the turbine last stage rotor blade 6 and causes erosion of the rotor blade, which may damage the rotor blade.

In particular, it is not preferable to continuously perform the turbine load operation in which the spray device 7 operates for a long time.
Therefore, normally, the continuous operation of the steam turbine cannot be performed in a turbine load in which the spray device 7 operates, specifically, in a load zone below the turbine load at which the turbine exhaust temperature is equal to or higher than the spray set temperature.

In the conventional casing exhaust chamber cooling device 3 for a steam turbine, a turbine load (25% turbine load or less in the example of FIG. 5) in which the turbine exhaust temperature becomes equal to or higher than the spray set temperature (casing exhaust chamber spray operating point) c However, there is a problem that the steam turbine cannot be continuously operated under low load.

On the other hand, in recent thermal power plants,
For example, there is an increasing demand for continuous low-load operation of about 15% turbine load.

Therefore, in the steam turbine power generation facility (plant), continuous operation of a low load, that is, a turbine load below the turbine exhaust chamber spray operating point (spray set temperature) c is required. There is a need for the advent of a steam turbine casing exhaust chamber cooling system that enables it.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a casing exhaust chamber cooling device for a steam turbine capable of continuously operating a steam turbine power generation facility under a low load.

Another object of the present invention is to improve the reliability of the steam turbine casing exhaust chamber by enabling continuous operation in a low load zone below the turbine load where the turbine exhaust temperature is above the casing exhaust chamber spray operating point and below the turbine load. To provide a cooling device.

[0021]

In order to solve the above-mentioned problems, a casing exhaust chamber cooling device of a steam turbine according to the present invention has a spray device for cooling an exhaust region and a turn-up region in a casing exhaust chamber of a steam turbine. A cooling spray device and a spray device for cooling are respectively provided so that only the spray device for cooling the exhaust region is operated during the low load operation of the steam turbine.

[0022]

The casing exhaust chamber cooling device of this steam turbine is provided with a spray device for cooling the exhaust region and a spray device for cooling the turn-up region in the casing exhaust chamber, and only the spray device for cooling the exhaust region is operated during low load operation of the steam turbine. It was operated so that the spray water sprayed from the spray device was guided only to the exhaust area, and the spray water was not sprayed to the turn-up area. Never get caught. Therefore, it is possible to perform continuous operation without damaging the steam turbine even in a low load zone below the turbine load, which is equal to or higher than the turbine exhaust chamber spray operating point.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a casing exhaust chamber cooling device for a steam turbine according to the present invention will be described below with reference to the accompanying drawings.

The present invention can be applied to steam turbine power generation equipment such as a thermal power generation plant and a nuclear power generation plant, and particularly preferably applied to the turbine exhaust side of a low pressure steam turbine provided in the steam turbine power generation equipment.

As shown in FIGS. 1 and 2, the steam turbine 10 has an inner casing 12 housed in an outer casing 11, and a turbine paragraph 13 composed of turbine rotor blades and vanes is housed in the inner casing 12. Reference numeral 14
Shows a turbine last stage rotor blade which constitutes the last stage of the turbine stage 13.

On the other hand, a low pressure casing exhaust chamber 15 is formed on the turbine exhaust side in the outer casing 11. The casing exhaust chamber 15 includes an exhaust region 15a and an exhaust region 1
It is divided into a turn-up region 15b located on the upstream side of 5a, and the turn-up region 15b is formed adjacent to the downstream side of the turbine last stage moving blade 14.

Further, the casing exhaust chamber 15 is provided with a turbine exhaust chamber cooling device 16, and this cooling device 1
6 is a plurality of systems, for example, two systems of spray devices 17, 18
Is installed. One of the spray devices 17 and 18 is configured for cooling the exhaust region, and the other is configured for cooling the turn-up region.

The exhaust area cooling spray device 17 includes a spray nozzle 20 having a nozzle port directed toward the exhaust area 15a.
It has a ring-shaped spray header pipe 21 that supports the spray nozzle 20, a spray pipe 23 that connects the header pipe 21 to a water supply pipe 22, and a spray valve 24 provided in the middle of the spray pipe 23. A plurality of, for example, four spray nozzles 20 are arranged along the circumferential direction of the spray header pipe 21. The exhaust area cooling spray device 17 sprays (injects) spray water from the spray nozzle 20 toward the exhaust area 15b by opening the spray valve 24, and actively cools the outer casing 11.

In the spray nozzle 20 of the spray device 17 for cooling the exhaust region, the spray water is the turbine last stage moving blade 14
It is set so as not to enter the turn-up area 15b that may be caught in the. This spray device 17
In consideration of prevention of thermal deformation of the outer casing, is set to be opened when the turbine exhaust temperature reaches or exceeds the spray set temperature (casing exhaust chamber spray operating point) c (c <a) in FIG. Point a is the temperature limit of the outer casing 11. The turbine exhaust temperature is detected by an exhaust temperature detecting means such as a thermocouple 25 provided near the tip of the last blade of the inner casing 12.

The spray device 18 for cooling the turn-up area has a spray nozzle 26 having a nozzle opening directed toward the turn-up area 15b, and the spray nozzle 26.
It has a spray header pipe 27 to which is attached, a spray pipe 28 connecting the header pipe 27 to the water supply pipe 23, and a spray valve 29 provided in the middle of the spray pipe 28. The water supply pipe 23 is the spray device 20 for cooling the exhaust region.
It is also used as a common mother tube.

The spray device 18 for turn-up cooling is intended for cooling the turbine last stage moving blade 14. The spray water from the spray nozzle 25 is sprayed toward the turn-up region 15b, and the final stage motion is performed. It is designed so that it is not directly sprayed onto the wing 14. The spray valve 29 has a spray set temperature d (for example, 160 ° C. to 230 ° C., a <b <c) equal to or lower than the final stage moving blade limit temperature b shown in FIG. Set to work.

Next, the operation of the casing exhaust chamber cooling device will be described.

When the steam turbine power generation equipment is continuously operated under a normal load, the casing exhaust chamber cooling device 16 does not operate.

In addition, the steam turbine power generation equipment is, for example, 15
When continuously operated at a low load of%, the turbine exhaust temperature rises to point e in FIG. The rise of the turbine exhaust temperature is detected by a thermocouple 25 as an exhaust temperature detecting means, and the detection of the turbine exhaust temperature activates the spray device 17 for cooling the exhaust region, and spray water from the spray nozzle 20 to the exhaust region 15a. Injection and exhaust area 1
5a and eventually the outer casing 11 is cooled.

At this time, the spray device 17 for cooling the exhaust gas temperature is operated, but the spray device 18 for cooling the turn-up region has the turbine exhaust gas temperature e set to the spray set temperature d.
It does not work because it is below. Therefore, the spray water is not sprayed (injected) to the turn-up region 15b, and the sprayed spray water can be reliably prevented from colliding with the turbine last stage moving blades 14. Therefore, there is no possibility of erosion due to spray water on the turbine last stage moving blades 14, and there is no problem even if the steam turbine 10 is continuously operated at a low load.

Further, the turbine exhaust temperature is turned up due to some cause such as an abnormal increase in the exhaust pressure of the casing exhaust chamber 15 or an abnormally high reheat steam temperature. When the temperature reaches the point or higher, the exhaust gas temperature detecting means 25 detects the turbine exhaust gas temperature and the turn-up area cooling spray device 1 is detected.
8 is also activated, and the final stage moving blade 14 is cooled. In this case, the spray water injected from the spray device 18 may be caught in the turbine last stage moving blades 14, so that the steam turbine 10 cannot be continuously operated.

However, the phenomenon in which the temperature rises to the turbine exhaust temperature d at which the turn-up cooling spray device 18 operates may occur under transient operating conditions when the turbine is started or stopped, but normally continues. During operation (including low load operation), it is almost unlikely that the turbine exhaust temperature rises to point d or higher.

On the other hand, there is no particular problem even if a part of the spray water is caught in the turbine last stage moving blade 14 within a short operating time, such as during transient operation when starting or stopping the turbine.

The casing exhaust chamber cooling device 16 of the steam turbine 10 is provided with a spray device 17 for cooling the exhaust region and a spray device 18 for cooling the turn-up region, and when the load is low, only the spray device 17 for cooling the exhaust region is provided. By continuously operating while operating, and by operating the turn-up cooling spray device 18 when an abnormality occurs, continuous operation at low load becomes possible without impairing the reliability of turbine equipment.

FIGS. 3 and 4 show another embodiment of the casing exhaust chamber cooling device for a steam turbine according to the present invention.

The casing exhaust chamber cooling device 16A shown in this embodiment differs from the casing exhaust chamber cooling device 16 shown in FIGS. 1 and 2 in the configuration of the spray device 30 for cooling the exhaust region, and the other configurations are the same. Since they are not substantially different, the same reference numerals are given and their description is omitted.

In this exhaust area cooling spray device 30, the number of spray nozzles 33 attached to the spray pipe 32 is increased, and each spray nozzle 33 is brought close to the inner wall of the outer casing 11 and along the inner wall from the outer side in the radial direction. It is arranged inward. Each spray nozzle 3
3 sprays (sprays) spray water toward the inner wall of the outer casing 11. The spray pipe 32 includes a spray valve 34 and is connected to the water supply pipe 23.

As shown in FIG. 4, the exhaust area cooling spray device 30 is branched into a plurality of systems, for example, four systems via a ring-shaped spray header pipe 35, and the exhaust area cooling spray device 30 of each system is circumferentially arranged. Are arranged at equal intervals with a central angle of 90 °, for example. As shown in FIGS. 3 and 4, the spray device 30 for cooling the exhaust region is provided with spray nozzles 33 along the inner wall of the exhaust region of the outer casing 11, and sprays the spray water toward the inner wall so that spray water is generated. The possibility of being caught in the final stage moving blades 14 can be further reduced, and the cooling effect of the outer casing 11 can be improved.

Turn-up area cooling sprayer 18
1 is the same as that shown in FIGS. 1 and 2, and the valve operating temperature of the spray valve 29 is the point d (a <
d <b), which is not different.

Further, the valve operating temperature of the spray valve 34 of the spray device 30 for cooling the exhaust region is the point c (c <
a), which is not different from the spray valve 24 of the exhaust area cooling spray device 17 shown in FIGS. 1 and 2.

Also in the casing exhaust chamber cooling device 16A shown in FIGS. 3 and 4, the casing exhaust chamber 15 is effectively cooled by the spray water sprayed from the exhaust region cooling spray device 30, and the cooling effect of the outer casing 11 is improved. In addition, the turbine final stage moving blades 14 can be cooled by the spray water sprayed from the turn-up region cooling spray device 18 in the event of an abnormality.

In this case, during the low load operation of the steam turbine, only the exhaust region cooling spray device 30 is operated to cool the inside of the turbine exhaust chamber 15, and the spray water sprayed from this spray device 30 is the turbine last stage rotor blade. Since it is possible to prevent the steam turbine from being sucked in, continuous operation can be performed at a low load of the steam turbine power generation facility, and even if it is continuously operated, damage to the turbine equipment can be effectively prevented and reliability is improved.

[0048]

As described above, in the casing exhaust chamber cooling device of the steam turbine according to the present invention, the casing exhaust chamber is provided with the exhaust region cooling spray device and the turn-up region cooling spray device, respectively. Since it was set to operate only the exhaust area cooling spray device during low load operation of the turbine, the turbine exhaust chamber is effectively cooled by the spray water sprayed from this exhaust area cooling spray device, and Can be prevented from being caught in the turbine last stage rotor blades through the turn-up region, so that it is possible to perform a continuous operation at a low load, which was not possible with the conventional steam turbine power generation equipment.

In addition, even if continuous operation is performed at a low load,
Since it is possible to prevent the spray water from being caught in the turbine last stage rotor blade, it is possible to prevent damage to the turbine equipment and improve the reliability of the turbine equipment.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a casing exhaust chamber cooling device for a steam turbine according to the present invention.

FIG. 2 is a diagram showing an arrangement relationship of spray devices provided in the casing exhaust chamber cooling device of the steam turbine shown in FIG.

FIG. 3 is a view showing another embodiment of the casing exhaust chamber cooling device of the steam turbine according to the present invention.

FIG. 4 is a diagram showing a positional relationship of each spray device provided in the casing exhaust chamber cooling device shown in FIG.

FIG. 5 is a diagram exemplifying a relationship between a turbine load of a steam turbine and a turbine exhaust temperature.

FIG. 6 is a view showing a conventional casing exhaust chamber cooling device.

FIG. 7 is a view showing a positional relationship of spray devices provided in a conventional casing exhaust chamber cooling device.

[Explanation of symbols]

 10 Steam Turbine 11 Outer Casing 12 Inner Casing 13 Turbine Paragraph 14 Turbine Final Stage Blade 15 Casing Exhaust Chamber 15a Exhaust Region 15b Turn-up Region 16, 16A Casing Exhaust Chamber Cooling Device 17,30 Exhaust Region Cooling Sprayer 18 Turn-up Region Cooling spray device 20,26,44 Spray nozzle 21,27,35 Spray header pipe 22,28,32 Spray pipe 23 Water supply pipe 24,29,34 Spray valve

Claims (1)

[Claims] 1. A casing exhaust chamber of a steam turbine is provided with an exhaust area cooling spray device and a turn-up area cooling spray device, respectively, so that only the exhaust area cooling spray device is operated during low load operation of the steam turbine. A casing exhaust chamber cooling device for a steam turbine, characterized in that