JPH034723B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the cooling of a stopped steam turbine, and in particular to the cooling of a steam turbine that has been driven by high-temperature steam from a boiler or reheater. The present invention relates to a steam turbine cooling method and cooling device suitable for rapid cooling, and a steam turbine device.

[Prior Art] As shown in FIG. 1, a steam turbine device includes a high-pressure turbine 4, an intermediate-pressure turbine 8, and a low-pressure turbine 10.
It is composed of a combination of. Then, the main steam generated in the boiler A is introduced into the high-pressure turbine 4 from the steam introduction part of the high-pressure turbine 4 via the main steam pipe 1, the main steam stop valve 2, and the steam control valve 3 to perform work. Also, the steam exhausted from the steam exhaust part of the high-pressure turbine 4 to the low-temperature reheat pipe 5 is sent to the reheater B, and the steam reheated in the reheater B is combined and passed through the reheat valve 7 to the intermediate-pressure turbine 8. The reheated steam is introduced into the intermediate pressure turbine 8 from the reheating steam introduction section to perform work. Furthermore, the steam exhausted from the steam exhaust part of the intermediate pressure turbine 8 to the crossover pipe 9 is transferred to the low pressure turbine 1.
The steam exhausted from the low-pressure turbine 10 is collected in the condenser 11. Note that 12 in the figure is a vacuum pump, which operates to maintain the degree of vacuum within the condenser 11.

When inspecting the above-mentioned steam turbine equipment or repairing a malfunction, the steam turbine equipment must be stopped and the high-temperature parts must be cooled before it can be disassembled, making inspection and repair impossible. It is possible. Therefore, a device for cooling the steam turbine device is required. Of the steam turbine devices, the low-pressure turbine 10 is supplied with exhaust steam from the intermediate-pressure turbine 8 as it is,
It will only be about ℃. Therefore, even if the low-pressure turbine 10 is stopped and left alone, cooling proceeds in a relatively short period of time, and no special cooling means is particularly required. However, the high-pressure turbine 4 is supplied with main steam or reheated steam heated to 500°C to 600°C from boiler A or reheater B, respectively.
Since the intermediate pressure turbine 8 and the intermediate pressure turbine 8 are in a high temperature state when stopped, unless some special cooling method is taken to shorten the period of time required for cooling, inspections and inspections will be carried out over a long period of time.
Repairs cannot be made, and the steam turbine equipment will be unable to operate during that time, resulting in a disruption to the power supply.

Therefore, it becomes necessary to cool the high-pressure turbine 4 and the intermediate-pressure turbine 8 in a short period of time. As a conventional cooling method, there is a method described in Japanese Patent Publication No. 46-2282. In this conventional technology, when cooling a steam turbine, the steam inlet of the steam turbine is opened, and then the air extractor of the condenser is operated, and outside air is sucked in from the steam inlet. This cools the steam turbine.

In the conventional technology described in Japanese Patent Application Laid-Open No. 56-32014,
The steam turbine is cooled by pumping outside air from the steam exhaust part of the steam turbine, passing it through the steam turbine, and exhausting it from the steam introduction part.

In the conventional technology described in Japanese Patent Application Laid-open No. 56-162212,
If outside air is forced in from the steam exhaust part of the low-pressure turbine using a pump, the pressure inside the low-pressure turbine will rise and the pressure safety valve will operate. During cooling, a pump sucks air inside the low-pressure turbine and pushes this air through the steam exhaust section of the high-pressure turbine to cool the high-pressure turbine.

[Conventional technology] A high-pressure turbine at a high temperature of 500°C to 600°C,
When cooling an intermediate pressure turbine, it is necessary to cool it so that thermal stress and thermal distortion do not occur. Therefore, uniform cooling throughout the steam turbine is required. Natural cooling is a good way to uniformly cool a steam turbine, which is a large structure, but relying on natural cooling takes time to cool down, which causes a reduction in turbine operating efficiency. Therefore, cooling is attempted using outside air, but each of the above-mentioned conventional techniques has the following problems.

The prior art described in Japanese Patent Publication No. 46-2282 has a structure in which outside air is sucked into a steam turbine through a steam introduction section and exhausted through a steam exhaust section. During normal operation of a steam turbine, high-temperature steam flows from the steam introduction section toward the steam exhaust section, so the temperature of the steam exhaust section is lower than the temperature of the steam introduction section. In other words, in the configuration of this prior art, the high temperature part (steam introduction part side) is first cooled with outside air, and then the high temperature part is cooled, and the low temperature part (steam exhaust part side) is cooled with the raised outside air. become. For this reason, the cooling of the low-temperature section does not progress as much as the cooling of the high-temperature section, and the temperature actually increases. Therefore, there are problems in that the entire steam turbine cannot be cooled uniformly, thermal stress and thermal deformation may occur, and the cooling efficiency is not very good.

The conventional techniques described in JP-A-56-320214 and JP-A-56-162212 both attempt to cool the high-pressure turbine by forcing outside air through the steam exhaust section of the high-pressure turbine. During normal operation, steam turbines are designed so that the pressure on the steam exhaust side becomes negative pressure and high-temperature steam flows from the steam introduction part to the steam exhaust side. It has a durable structure. For this reason, if outside air is forced into the steam turbine for cooling to create a positive pressure inside the steam turbine, as in this conventional technology, unexpected damage may occur, such as the atmospheric release plate being destroyed. . For this reason, it is difficult to apply this conventional cooling method as is to existing steam turbines.

In addition, in the prior art described in Japanese Patent Application Laid-Open No. 56-162212, a pump is provided in the crossover pipe, and the cooling air to be forced into the high-pressure turbine can be extracted from the low-pressure turbine by the pump. Low-pressure turbines do not have steam directly flowing into them from the boiler or reheater, so they do not get very hot, but the temperature can rise to nearly 300 degrees Celsius. For this reason,
The pump extracts air at 300°C and pumps it to the high-pressure turbine when cooling the steam turbine. In other words, there is a problem in that a normal pump cannot be used and a specially designed heat-resistant pump must be used. Moreover, even if a pump were to be installed to cool the steam turbine, workers would not be able to touch the 300°C crossover pipe, so the pump would have to be permanently installed in the crossover pipe. However, this causes steam to pass through this pump during normal operation, reducing the energy efficiency of the steam turbine. A more serious problem is that all the large-capacity steam turbine systems that most require shortened cooling periods have high-pressure and intermediate-pressure turbines, and as shown in this prior art, air is pumped using a pump installed in a crossover pipe. If you notice, the reheater installed between the intermediate-pressure turbine and the high-pressure turbine will also be included in the cooling target, and the high-pressure turbine will cool the reheater before being cooled, and the high-temperature air that flows backwards will cause the high-pressure turbine to cool down. This is not practically applicable as there is a risk of overheating.

An object of the present invention is to provide a cooling method and a cooling device that can uniformly and quickly cool even an existing steam turbine into which steam from a boiler or a reheater is introduced, and also to provide a cooling device equipped with this cooling device. Another object of the present invention is to provide a steam turbine device.

[Means for Solving the Problems] Among the above objects, the steam turbine cooling method sucks air from the steam introduction part of a high-pressure or intermediate-pressure turbine using an air suction device and introduces outside air into the turbine from the steam exhaust part. Furthermore, this can be achieved by cooling the high-temperature outside air discharged from the steam introduction section with a cooling device and then sucking it into the air suction device.

Among the above purposes, the steam turbine cooling system has an exhaust passage connected to the steam introduction part of the steam turbine that introduces steam from the boiler or reheater, and an air suction device that draws steam from the steam exhaust part of the steam turbine. This is achieved by providing an air cooling device that raises the temperature by cooling the inside and cools the outside air exhausted from the steam introduction section into the exhaust path.

Among the above objects, the steam turbine device is provided with, in addition to the steam turbine cooling device described above, a switching section that switches and connects the steam introduction path that connects the boiler or reheater and the steam introduction section and the exhaust path. And it will be achieved.

[Function] The steam turbine cooling method and steam turbine device of the present invention make the inside of the steam turbine a negative pressure by the suction action of the air suction device, and suck outside air from the steam exhaust section, so that the inside of the steam turbine is made to have a positive pressure. No problems will occur. In addition, the sucked outside air first cools the steam exhaust section on the low temperature side, and then the heated outside air further cools the steam introduction section on the high temperature side, making it possible to uniformly cool the entire steam turbine. . Furthermore, since the high temperature outside air flowing out from the steam introduction section is cooled by the cooling device and then sucked into the air suction device, there is no need to use a heat-resistant air suction device.

The steam turbine cooling device of the present invention has a configuration that allows the above cooling method to be performed simply by connecting it to the steam introduction part from the boiler or reheater, that is, nothing is installed in the steam flow path during normal operation. Because it is an external addition to the steam turbine installation, the presence of this cooling device does not have an adverse effect during normal operation of the steam turbine. Further, since the high temperature outside air after cooling exhausted from the steam turbine is cooled by the cooling device and then sucked into the air suction device, the air suction device is not damaged by the high temperature outside air. Therefore, it becomes possible to use the existing air suction device in the condenser.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 2 to 8.

In FIG. 2, a high-pressure turbine exhaust path 1 is connected to a branch pipe of a drain valve 15 provided at the outlet of the main steam stop valve 2.
In addition, an intermediate pressure turbine exhaust path 19 is connected to a branch pipe of a drain valve 16 provided on the outlet side of the combined reheat valve 7, and stop valves 22 and 23 are connected to these exhaust paths 18 and 19, respectively. They are connected to the suction side of an air suction device (hereinafter referred to as a vacuum pump, since it is convenient to use a vacuum pump in terms of size and the like) through an exhaust path 20. A cooling device 21 is inserted in the middle of this exhaust path 20. A steam turbine device is configured by attaching a cooling device having such a configuration to the high-pressure turbine 4 and the intermediate-pressure turbine 8.

In this cooling device, the main steam stop valve 2, combination reheat valve 7, drain valves 15, 16, blowdown valve 14, and vacuum pump inlet valve 26 are fully closed, while the valves 22, 23 provided on the cooling device side, 24,2
5, the vacuum break valve 17 provided in the condenser 11, the steam control valve 3, and the ventilator valve 13 are fully opened. Then, when the vacuum pump 12 is started, outside air is sucked into the steam turbine device from the vacuum breaker valve 17.

That is, by driving the vacuum pump 12, the exhaust path 2
The suction force acts on 0, 18, 19, and the vacuum breaker valve 1
7, the outside air C flows into the condenser 11 as shown in FIG.
sucked inside. This outside air C is passed from inside the condenser 11 through the low pressure turbine 10 to the crossover pipe 9
and enters the intermediate pressure turbine 8 from the steam exhaust section of the intermediate pressure turbine 8. This outside air is transferred to the intermediate pressure turbine 8
The outside air, which has been cooled from the low-temperature side, flows to the high-temperature side of the intermediate-pressure turbine 8, cools the high-temperature side, and is discharged from the steam introduction section of the intermediate-pressure turbine 8 into the exhaust passage 19. Thereby, the intermediate pressure turbine 8 is cooled. On the other hand, the outside air C drawn into the condenser 11 is
The steam enters the high-pressure turbine 4 from the steam exhaust part of the high-pressure turbine 4 through the ventilator valve 13 and the low-temperature reheat pipe 5, cools the high-pressure turbine 4, and is discharged from the steam introduction part to the exhaust passage 18.

The outside air exhausted into the exhaust passages 18 and 19 has a temperature of 500°C.
Since the temperature has risen to ~600°C, if this temperature is directly sucked into the vacuum pump 12, the vacuum pump 12 will break down and become unable to operate after the periodic inspection is completed. However, in the present invention, this high-temperature outside air is cooled by the air suction device 21 and then sucked into the vacuum pump 12 and discharged into the atmosphere, so no problem occurs.

In this way, by the suction action of the vacuum pump 12, outside air is drawn into the high pressure turbine 4 and into the intermediate pressure turbine 8.
Since cooling is performed by flowing from the low temperature side to the high temperature side, the outside air that cools the high temperature side becomes the outside air whose temperature has been raised on the low temperature side. Therefore, the present invention avoids deformation and damage caused by thermal stress that would occur when cold outside air is suddenly introduced into the high temperature parts of the high pressure turbine 4 and the intermediate pressure turbine 8 to cause rapid cooling. Furthermore, since outside air is continuously sucked in and distributed, the high pressure turbine 4 and the intermediate pressure turbine 8 can be cooled in a short time.

In this embodiment, the outside air for cooling the high-pressure turbine 4 is introduced directly from the condenser 11 into the steam exhaust section of the high-pressure turbine 4, whereas the outside air for cooling the intermediate-pressure turbine 8 is introduced after passing through the low-pressure turbine 8. It is introduced into the steam exhaust section of an intermediate pressure turbine. In other words,
The outside air that cools the high-pressure turbine 4 is initially at atmospheric temperature, while the outside air that cools the intermediate-pressure turbine passes through the low-pressure turbine and becomes outside air with a raised temperature.
Therefore, when the high-pressure turbine 4 and the intermediate-pressure turbine 8 are stopped after normal operation, they are at approximately the same temperature.
The cooling balance will become unbalanced. However, as will be described later, this means that both turbines 4,
It can be adjusted by controlling the flow rate of outside air flowing through the interior of the air. This can also be achieved by newly installing a cooling bypass passage that prevents the outside air for cooling the intermediate-pressure turbine 8 from passing through the low-pressure turbine. In this example, the reason why the intermediate pressure turbine is cooled with outside air that has passed through the low pressure turbine is that it is also used to cool the low pressure turbine, and at the same time, there is no need to add any equipment other than the cooling device. This is because the configuration is configured to use only .

The details of this example will be explained in more detail below.

In Fig. 2, which shows the state in which the steam turbine equipment is normally operating, the steam generated in boiler A is
Pass through main steam pipe 1, main steam stop valve (MSV) 2,
After the flow rate is controlled by a steam control valve (CV) 3, the steam flows into the high-pressure turbine 4 through its steam introduction section and does work. The steam that has finished its work is discharged from the steam exhaust section to the low-temperature reheat pipe 5, passes through the check valve 6, and enters the reheater B.
is guided and heated. The reheated steam heated in reheater B in this way is transferred to the combined reheat valve (CRV).
7, the reheated steam flows into the intermediate pressure turbine 8 from the reheating steam introduction section to do work, and is then discharged from the steam exhaust section of the intermediate pressure turbine 8 to the crossover pipe 9. The steam discharged into the crossover pipe 9 performs work in a low pressure turbine 10 and is then recovered in a condenser 11.

A vacuum pump (or ejector) 12 is generally installed in the condenser 11 to maintain the degree of vacuum in the condenser 11 at all times. The ventilator valve 13 is in the "closed" state during normal operation, but when the steam control valve 3 is fully closed and the high-pressure turbine 4 is stopped, the ventilator valve 13 is in the "open" state and the steam in the high-pressure turbine 4 is restored. The water is collected in the water container 11. At the same time, the blowdown valve 14 is in the "closed" state during normal operation, but when the intercept valve (not shown) of the combined reheat valve 7 is fully closed, it becomes the "open" state, and the blowdown valve 14 is in the "open" state. The steam is recovered in the condenser 11.

The drain valves 15 and 16 are attached to the main steam stop valve 2 and the outlet side of the combination reheat valve 7 by providing branch pipes, and are in a fully closed state during normal operation. The drain valves 15 and 16 are fully opened when the turbine is started or stopped, and the drain in the system is recovered to the condenser 11. The vacuum breaker valve 17 is
This is to destroy the vacuum in the condenser 11, and during normal operation it is fully closed to maintain the vacuum in the condenser 11. After the turbine is stopped, the vacuum pump 1
When 2 is also stopped, it is fully opened to destroy the vacuum inside the condenser 11.

In the steam turbine device configured in this manner, the high-pressure turbine exhaust path 18 and the intermediate-pressure turbine exhaust path 19 are connected to the branch pipes of the drains 15 and 16, respectively, and these two exhaust paths 18 and 19 are connected to the branch pipes of the drains 15 and 16. A cooling device 21 is connected to the exhaust path 20 via stop valves 22 and 23, and a cooling device 21 is provided in the middle of the exhaust path 20.
5, and this cooling air exhaust system is attached to the steam turbine device as a steam turbine cooling device.

That is, by the vacuum pump 12, the exhaust path 18,
Apply suction force to 19 and 20, and with this suction force,
Outside air is sucked into the condenser 11 from the vacuum breaker valve 17 in a fully open state, and this outside air is passed through the low pressure turbine 10 → crossover pipe 9 → intermediate pressure turbine 8 → intermediate pressure turbine exhaust path 19, and the ventilator valve 13
→ High pressure turbine 4 → High pressure turbine exhaust passage 18, and the high-temperature outside air that is joined at exhaust passage 20 is cooled by cooling device 21 and discharged to the atmosphere by vacuum pump 12.

The reason why the stop valves 22 and 23 are provided is to enable selective cooling of either the high pressure turbine 4 or the intermediate pressure turbine 8. By using the stop valves 22 and 23 as flow rate control valves, the flow rate of the cooling outside air flowing to the high-pressure turbine 4 and the flow rate of the cooling outside air flowing to the intermediate-pressure turbine 8 are adjusted to uniformly cool both turbines. It becomes possible to

Next, the operation of this embodiment configured as above will be explained.

First, during normal operation, steam flows through the path as shown in FIG. 2, and the turbine is operated (in the figure, the valves painted black indicate the "closed" state).

In this normal operating state, if the turbine stops for some reason, the main steam stop valve 2, steam control valve 3, and combination reheat valve 7 are fully closed to cut off the flow of steam into the turbine. The ventilator valve 13 and the blowdown valve 14, which were in the "closed" state during operation, are fully closed, and the steam in the high-pressure turbine 4 flows into the condenser 11.
Next, the drain valves 15 and 16 are fully opened, and the drain in the system is discharged into the condenser 11 (this state is shown in FIG. 3). In this state, the turbine completely stops, but next, the steam turbine is in a high temperature state, especially the high pressure turbine 4, into which main steam from boiler A was directly flowing, and the reheat from reheater B. A preparatory operation is required to cool down the intermediate pressure turbine 8 into which steam was directly flowing.

Preparation operations are performed using the interlock shown in FIG. Turn on the turbine cooling button, fully close the main steam stop valve (MSV) 2, fully close the combined reheat valve (CRV) 7, and confirm that the steam inflow to the turbine is blocked. After confirming turning to prevent deformation and confirming that the vacuum breaker valve 17 is fully open, when all of these conditions are met,
Start the oil pump (not shown) to secure bearing oil and control oil for the turbine, fully open the steam control valve (CV) 3, fully close the vacuum inlet valve 26, fully open the ventilator valve (VV) 13, and fully open the drain valves 15 and 16. When closed, preparation for cooling is completed. As a result, the interlock is canceled and the vacuum pump 12 is started, at the same time.
The control device 55 operates (see FIG. 5), and the stop valves 22, 23, 24 of the steam turbine cooling system operate in the opening direction. As a result, as described above, outside air is sucked into the condenser 11 through the fully open vacuum breaker valve 17 (see FIG. 6).

In this way, a part of the outside air sucked into the condenser 11 flows into the exhaust side of the low pressure turbine 10, cools the metal of the low pressure turbine 10, and then passes through the crossover pipe 9 to the intermediate pressure turbine 8. After cooling the intermediate pressure turbine 8, it is discharged to the intermediate pressure turbine exhaust path 19. On the other hand, the outside air that has flowed toward the ventilator valve 13 side flows into the exhaust side of the high-pressure turbine 4 to cool the high-pressure turbine 4, and then is discharged to the high-pressure turbine exhaust path 18. In this way, the outside air discharged into the exhaust passages 18 and 19 is guided to the cooling device 21 through the exhaust passage 20, cooled, and discharged into the atmosphere by the vacuum pump 12. In this way, outside air is continuously sucked in through the open vacuum breaker valve 17 to forcibly cool the turbine.

In this cooling process, a flow of cooling air flows from a low-temperature section to a high-temperature section of the steam turbine device, and during this time the temperature of the cooling air is raised.

In this way, the temperature difference between the temperature of the cooling air, which is raised during the cooling process, and the metal temperature, which is cooled and lowered, is approximately constant at each part of the cooling process, and is approximately uniform over the entire area. It is cooled at a cooling rate of .

In this example, the flow of cooling air was explained using the names of various valves attached to the steam turbine, but the installation positions and locations may differ depending on the individual steam turbine.
Although there seems to be a difference in the presence or absence of installation, the basic configuration is the same in all cases, and the flow of cooling air is also the same as in this embodiment.

Next, a method of balancing the cooling by making the cooling rates of the high-pressure turbine 4 and the intermediate-pressure turbine 8 uniform will be described.

Since the vacuum pump 12 is operated at a constant speed, the overall cooling rate of the high-pressure turbine 4, intermediate-pressure turbine 8, and low-pressure turbine 10 is controlled by the air flow rate control by the valve 24 (the valve 25 is operated at a constant speed during normal operation). This is a stop valve for isolating the cooling system.) On the other hand, the respective cooling drop rates of the high-pressure turbine 4 and the intermediate-pressure turbine 8 (including the low-pressure turbine 10 in this embodiment) are as follows:
This is done by adjusting the valves 22 and 23.

That is, in FIG. 7, signals from the high-pressure turbine metal temperature detector 51 and the intermediate-pressure turbine metal temperature detector 52 are input to the temperature drop rate calculating section of the control device 55, and here, the signals from the high-pressure turbine metal temperature detector 51 and the intermediate-pressure turbine metal temperature detector 52 are inputted to the temperature drop rate calculation section of the control device 55, and the signals from the Calculate the metal temperature drop rate of the intermediate pressure turbine and the metal temperature drop rate of the intermediate pressure turbine. The actual metal temperature drop rates of the high-pressure turbine 4 and the intermediate-pressure turbine 8 calculated in this way are compared with respective set values, and the comparison results are output. As a comparison result, when the temperature drop rate is larger than the set value, “1” is output from the “large” output terminal.
"0" is output from the "small" output terminal, and when the temperature drop rate is smaller than the set value, "0" is output from the "large" output terminal, and "1" is output from the "small" output terminal. From this comparison result signal, an operation signal is generated by four NOT circuits and six AND circuits indicated by X marks in FIG. 7, and the input valves 22, 23, and 24 are opened and closed.

For example, if the temperature drop rates of both the high-pressure turbine 4 and the intermediate-pressure turbine 8 become larger than their respective set values, a "close" signal is input to the controller, the valve 24 is throttled, and the total air volume (outside air flow rate) decreases. At this time, no operation signal is input to the operation device, and the opening amounts of the valves 22 and 23 do not change. Therefore, the ratio of the amount of cooling air flowing into each turbine 4, 8 remains the same, but only the flow rate is reduced, and the rate of temperature drop is reduced.

Even when the temperature drop rates of the high-pressure turbine 4 and the intermediate-pressure turbine 8 become smaller than their respective set values, no operation signal is input to the controller, and the opening amounts of the valves 22 and 23 do not change. However, when an "open" signal is input to the operating device, the opening amount of the valve 26 increases, and the overall air flow rate increases. Therefore, the temperature drop rate of the high-pressure turbine 4 and the intermediate-pressure turbine 8 increases.

If the temperature drop rates of the high pressure turbine 4 and the intermediate pressure turbine 8 are different, for example, if the temperature drop rate of the high pressure turbine 4 is larger than the set value and the temperature drop rate of the intermediate pressure turbine 8 is smaller than the set value. , no operation signal is input to the controller, and the overall cooling air flow rate remains unchanged. However, a "close" signal is input to the operating device, and an "open" signal is input to the operating device.
As a result, the amount of cooling air flowing to the high-pressure turbine 4 is throttled, and the amount of cooling air flowing to the intermediate-pressure turbine 8 is increased. In this way, the distribution of the amount of air flowing through both turbines 4, 8 is changed, and the rate of temperature drop in both turbines is adjusted.

With this input signal, for example, the high pressure turbine 4
The metal temperature drop rate becomes large, and the intermediate pressure turbine 8
When the metal temperature drop rate becomes large, a "close" signal is input to the operating device, reducing the overall air volume (outside air flow rate) and at the same time operating the operating device in the "close" direction. , the amount of air is finely adjusted in the direction of decreasing it. On the contrary, when the metal temperature drop rate of the high and intermediate pressure turbines 4 and 8 becomes small, an "open" signal is input to each operating device,
Air volume is increased.

In this case, the operating condition of the operating device is that both the high and intermediate pressure turbines 4 and 8 are operated only when the valve opening/closing operation signal of the metal temperature drop rate is the same.

Therefore, if the valve opening/closing operation signals for the metal temperature drop rate of the high and intermediate pressure turbines 4 and 8 are different, the operating device will not operate, so the absolute amount of cooling air will not change and the high and intermediate pressure turbines 4 and 8 Input both valve opening/closing operation signals to the respective actuators, and
High and medium pressure turbines 4 and 8
The amount of cooling air is distributed so that the metal temperature drop rate is adjusted.

The cooling status of the high and medium pressure turbines 4, 8 performed in this manner is compared with the target cooling metal temperature by a comparator, and an indicator light indicates whether cooling is in progress or complete.

As the temperature detectors 51 and 52 mentioned above, it is also possible to use commonly provided ones for monitoring.

Fig. 8 shows an experimental example of cooling in this way.The number of days required to reach the target cooling temperature 63 is now 1 to 2 days, whereas conventionally (curve 61) it took 4 to 5 days. It has been confirmed that the time has been shortened to 1 day.

In the above description, the amount of cooling air is adjusted by detecting the temperature of the turbine metal, but the amount of cooling air may be adjusted using thermal stress or thermal expansion difference of the turbine metal.

[Effects of the Invention] According to the present invention, the high-pressure turbine and the intermediate-pressure turbine are cooled by using the suction method and flowing the cooling air in the opposite direction to the flow of steam during normal operation.
The temperature difference between the temperature rise of the cooling air and the temperature fall of the turbine metal during the cooling process can be made uniform from the steam introduction part side to the steam exhaust part side of the turbine, and the problem of thermal stress and thermal deformation due to cooling can be reduced. It disappears. Furthermore, since the flow rate of cooling air can be adjusted, safety and reliability are further improved in terms of thermal stress and thermal deformation.

Furthermore, since outside air is continuously drawn into the steam turbine and forcedly cooled, the time required for cooling is significantly shortened, and the operating rate of the steam turbine device is significantly improved. Furthermore, since cooling is possible simply by adding a cooling device, it can be applied to existing steam turbine equipment, making it possible to significantly improve safety, reliability, and operating efficiency.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a conventional steam turbine device, Figs. 2 to 8 are related to an embodiment of the present invention, Fig. 2 is an explanatory diagram of a steam system during normal operation, and Fig. 3 is an explanatory diagram of a steam system during normal operation. State explanatory diagram when the turbine is stopped, 4th
Figure 5 is an interlock diagram for cooling preparation operations, Figure 5 is a control diagram for cooling, Figure 6 is an explanatory diagram of the system for cooling outside air during cooling, Figure 7 is a control block diagram, FIG. 8 is a metal cooling graph comparing the effects of the conventional example and the present invention. A... Boiler, B... Reheater, 1... Main steam pipe, 2... Main steam stop valve, 3... Steam control valve, 4
...High pressure turbine, 7... Combination reheat valve, 8...
Medium pressure turbine, 12... Vacuum pump, 13... Ventilator valve, 17... Vacuum breaker valve, 18, 1
9, 20...Exhaust path, 21...Cooling device, 22,
23, 24, 26... valve.

Claims (1)

[Claims] 1. A steam introduction section that introduces steam from a boiler;
In a steam turbine normally operated by passing steam from the steam introduction part to the steam exhaust part, when cooling the stopped steam turbine, the steam introduction part The steam turbine is cooled by sucking in air from the air through a cooling device with an air suction device, sucking outside air from the steam exhaust portion side, passing it through the steam turbine, and exhausting it from the steam introduction portion to the outside of the steam turbine. A method for cooling a steam turbine characterized by: 2. A method for cooling a steam turbine according to claim 1, characterized in that the temperature drop rate of the steam turbine is adjusted by controlling the flow rate of outside air drawn into the steam turbine. 3 A high-pressure turbine that is normally operated by introducing main steam from a boiler, and an intermediate-pressure turbine that is normally operated by introducing reheated steam that is discharged from the steam exhaust part of the high-pressure turbine and reheated in a reheater. In a steam turbine device comprising a turbine, when cooling the stopped steam turbine device, an air suction device is provided from a main steam introduction section of the high pressure turbine and a reheat steam introduction section of the intermediate pressure turbine via a cooling device. The outside air is sucked in from the steam exhaust part of the high-pressure turbine and the steam exhaust part of the intermediate-pressure turbine, and the outside air is passed into the high-pressure turbine and the intermediate-pressure turbine to connect the main steam introduction part and the A method for cooling a steam turbine, characterized in that each high-pressure turbine and intermediate-pressure turbine are cooled by discharging reheated steam from an introduction section. 4 In claim 3, cooling of the high-pressure turbine and the intermediate-pressure turbine is balanced by controlling the flow rate of outside air drawn into the high-pressure turbine and the flow rate of outside air drawn into the intermediate-pressure turbine. A method for cooling a steam turbine, characterized by: 5. A cooling device comprising a steam introduction part and a steam exhaust part connected to a boiler and cooling a normally operated steam turbine by passing steam from the steam introduction part to the steam exhaust part, which an exhaust path that connects the steam introduction section to an air suction device when cooling the steam turbine; and an exhaust path that connects the steam introduction section to an air suction device that is sucked into the steam turbine from the steam exhaust section by the operation of the air suction device; A cooling device for cooling a steam turbine, the cooling device comprising: a cooling device that cools outside air that is exhausted to the outside of the steam turbine upstream of the air suction device. 6. A steam turbine having a steam introduction part and a steam exhaust part, a steam introduction passage and a cooling outside air exhaust passage provided on the side of the steam introduction part, and a steam turbine for directing steam from a boiler through the steam introduction passage during normal operation. a switching unit that introduces the steam into the steam turbine from the steam introduction part and switches the connection between the steam introduction part and the steam introduction path to connect the exhaust passage to the steam introduction part during cooling operation after the steam turbine is stopped; an air suction device provided at the other end of the exhaust passage and activated during the cooling operation; and outside air drawn into the steam turbine from the steam exhaust section by the suction action of the air suction device during the cooling operation to the outside of the steam turbine. a cooling device that cools the air after the air is discharged through the exhaust path and before being sucked into the air suction device. 7 A high-pressure turbine having a main steam introduction part and a steam exhaust part and normally operated by introducing main steam from the boiler, and a high-pressure turbine having a reheat steam introduction part and a steam exhaust part and producing steam from the high-pressure turbine. An intermediate-pressure turbine that is normally operated by introducing reheated steam that is discharged from an exhaust section and then reheated in a reheater, an exhaust path for cooling outside air, the high-pressure turbine that has been stopped, and the a switching part that connects the exhaust passage to the main steam introduction part and the reheat steam introduction part during a cooling operation to cool the intermediate-pressure turbine; and a switching part that is provided at the other end of the exhaust passage and is activated during the cooling operation. A steam turbine device comprising: an air suction device; and a cooling device provided in the exhaust path between the switching section and the air suction device.