JPS62324B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a warming device for a steam turbine in a steam turbine plant.

[Technical background of the invention]

Recently, as the capacity of power plants has increased, steam turbines have become larger. Transformation plants, which play a major role in balancing the supply and demand of electricity, or ultra-high pressure, high temperature power generation plants that use steam at higher pressures and temperatures etc. are being reviewed.

By the way, as mentioned above, one of the roles of the above-mentioned transformer plants is to balance the supply and demand of electricity, so even if it is a large-scale power generation plant, it is not possible to continue operating at a high load as in the past, and it is difficult to keep up with demand. Depending on supply differences, the frequency of plant shutdowns increases. In addition, if the steam conditions are increased to high pressure and temperature, the steam turbine casing body will naturally become thicker and larger in shape, and the rotor diameter will also need to be larger in order to obtain sufficient strength against the centrifugal force caused by high-speed rotation. Become.

However, in a steam turbine with such a large and complex shape, if the inner surface temperature of the first stage casing is low at startup, the casing and rotor of the steam turbine must be heated to the transition temperature ( It is necessary to warm up the boiler to a temperature of approximately 140°C or higher to prevent low-temperature brittle fracture and to reduce the temperature difference between the boiler and the high-temperature steam that flows in from the boiler at startup to alleviate excessive temperature changes.

FIG. 1 is a system diagram of a steam turbine plant equipped with a conventional warming device, in which high-temperature, high-pressure main steam generated in a boiler superheater 1 passes through a main steam pipe 2 to a main steam stop valve 3 and a steam control valve. It is introduced into the high pressure turbine 5 via the valve 4. The steam introduced into the high-pressure turbine 5 thermally expands there and performs work, and then is guided to the boiler reheater 7 by the low-temperature reheat steam pipe 6 and heated again. The reheated steam is passed through the high temperature reheat steam pipe 8.
is supplied to the intermediate pressure turbine 11 via the reheat steam stop valve 9 and the intercept valve 10. After the steam supplied to the intermediate pressure turbine 11 performs work there, it is further introduced into the low pressure turbine 12 to perform work, and is connected to the rotor shafts of the high pressure turbine 5, intermediate pressure turbine 11, and low pressure turbine 12. The generator 13 is driven. On the other hand, the steam that has expanded and completed its work in the low-pressure turbine 12 is introduced into the condenser 14 and is condensed.

By the way, the low-temperature reheat steam pipe 6 includes an auxiliary steam main pipe 16 to which auxiliary steam is supplied from an auxiliary boiler or other auxiliary steam source 15, and a warming steam pipe 19 having a warming pressure control valve 17 and a stop valve 18. connected by. On the other hand, a main steam pipe drain pipe 20 is connected to the downstream side of the steam control valve 4 of the main steam pipe 2, and a high pressure casing drain pipe 22 and a bleed pipe drain pipe 23 are connected to the inlet of the high pressure turbine 5 and the bleed pipe 21, respectively. is connected. Further, a low temperature reheat steam pipe drain pipe 24 and a high temperature reheat steam pipe drain pipe 25 are connected to the low temperature reheat steam pipe 6 and the high temperature reheat steam pipe 8, respectively, and each drain pipe has a drain valve 20a. ,2
2a, 23a, 24a, and 25a are provided.

Therefore, when warming the turbine, the main valves such as the main steam stop valve 3, the steam control valve 4, the reheat steam stop valve 9, and the intercept valve 10 are kept fully closed, and the warming pressure control valve 17 and The stop valve 18 is opened and warming steam is supplied from the auxiliary steam main pipe 16 to the low temperature reheat steam pipe 6. Then, the warming steam that has flowed into the low-temperature reheat steam pipe 6 flows into the high-pressure turbine 5, and at the same time flows into the boiler reheater 7, and further into the high-temperature reheat steam pipe 8, where it is reheated. The steam is cut off by the steam stop valve 9 and the entire system of the boiler reheater 7 is filled. On the other hand, the warming steam that has flowed into the high-pressure turbine 5 fills the high-pressure turbine 5, and at the same time, the high-pressure turbine 5 is sealed by the steam control valve 4 and the main steam stop valve 3.

Therefore, when the warming pressure control valve 17 is further opened to supply warm steam, the entire system of the high pressure turbine 5 and the boiler reheater 7 between the main steam stop valve 3, the steam control valve 4, and the reheat steam stop valve 9 is The pressure increases, and this pressure is maintained by the warming pressure control valve 17 at 4 to 5 atg, which is the saturated steam pressure at the target temperature of 150°C.

The steam sealed in the high pressure turbine 5 etc. is
By coming into contact with the low-temperature metal surfaces of the high-pressure turbine 5, boiler reheater 7, low-temperature reheat steam pipe, high-temperature reheat steam pipe 8, etc., the retained heat is taken away, and the metal temperature of each part increases. I am forced to do it. As a result, the enthalpy of the steam decreases and some of the steam is converted into drain, but the drain generated at this time is drained from drain pipes installed at low places in various parts, namely, the main steam pipe drain pipe 20, the high pressure casing drain pipe 21, and the bleed pipe. It is discharged together with a portion of the warming steam from the drain pipe 23, the low temperature reheat steam pipe drain pipe 24, the high temperature reheat steam pipe drain pipe 25, and the like. On the other hand, the pressure drop due to condensation of the sealed steam and the decrease in steam amount due to outflow from the drain pipe are supplemented by warming steam supplied by adjusting the opening degree of the warming pressure regulating valve 17.

In this way, each part of the high temperature turbine etc. is uniformly warmed to the target temperature by the contact between the warming steam and the low temperature metal.

[Problems with background technology]

However, with respect to the high-pressure turbine 5, the boiler reheater 7 and the accompanying low-temperature reheat steam pipe 6 and high-temperature reheat steam pipe 8 are significantly different from each other in terms of volume and metal surface area. , is overwhelmingly large. For example, a 600MW class boiler has a volume of over 300m ³ , whereas a high-pressure turbine has a volume of around 80m ³ . Therefore, there is naturally a corresponding difference in the metal area that comes into contact with the warming steam, and most of the warming steam is spent warming the system of the boiler reheater 7, which is the main object of warming. Warming is prioritized over the high-pressure turbine 5, and as a result, it inevitably takes a long time to bring the high-pressure turbine to the target temperature. In other words, if the high-pressure turbine is completely cold, it may take a whole day and night, and the system of the high-pressure turbine 5 and boiler reheater 7 has a large resistance to steam passage due to its structural complexity. There is a tendency for steam to flow less easily to the 5 side, which results in the aggravation of the above phenomenon.

Additionally, as mentioned above, high-temperature, high-pressure turbines have thick casings and large rotor diameters.
The temperature of the metal at the surface in contact with the steam is the target
There are also problems such as there being no effective and effective means to rapidly bring the entire area up to the outer surface of the casing or the center of the rotor to the target temperature once the temperature reaches 150°C.

The pressure of the high pressure turbine during warming is 4~
As mentioned above, warming is performed while maintaining the temperature at 5atg, but since the target temperature is 150℃, this pressure is the saturated steam pressure, and there is also a restriction due to the thrust force applied in the turbine axial direction. It is based on

In other words, the rotating body of a steam turbine was configured to have a certain degree of freedom in axial elongation due to thermal expansion due to temperature rise, and to absorb this, and the axial force was supported by thrust bearings. . Therefore, if the difference in elongation between this axial elongation and the casing becomes abnormal, it may cause abnormal wear of the thrust bearing.

In addition, thrust bearings are designed according to the maximum thrust force generated during steam turbine operation.
It does not take into account irregular conditions for the turbine such as warming. Therefore, when thrust force is generated by warming the turbine, it is naturally necessary to perform the warming within the range allowed by the thrust bearing.

Furthermore, in a high-pressure turbine, the areas to which the thrust force due to internal pressure is applied are different at the steam inlet and outlet, and the thrust force is naturally applied in one direction to the rotating body, and the force due to the flow of warming steam is also applied as a thrust force. Since it is added,
The pressure during warming cannot be increased indefinitely. Therefore, there is naturally a limit to the steam temperature, and the current situation is that it takes quite a long time to raise the entire casing and rotating body to the target temperature, that is, to complete warming.

Furthermore, since the warming steam temperature is limited as mentioned above, there is a difference between the steam temperature from the boiler (approximately 350 to 400 degrees Celsius) at the time of turbine startup, and thermal stress still occurs in the rotor etc. at the time of startup. There are also problems.

[Purpose of the invention]

In view of these points, the present invention can eliminate the restriction on the warming temperature and shorten the warming time, and also reduce the temperature difference with the high-temperature steam flowing from the boiler when starting the turbine.
It is an object of the present invention to provide a steam turbine warming device that can reduce thermal stress generated during startup and extend the life of a turbine.

[Summary of the invention]

The present invention provides a first warming steam pipe connected to an intermediate stage of a turbine and having one end connected to a warming steam source or a condenser; is the pressure of the second and third warming steam pipes connected to the condenser or warming steam source corresponding to the first warming steam pipe, the intermediate stage of the turbine, the main steam inlet part and the exhaust part. Each warming steam pipe is provided with pressure detectors for detecting the respective pressures and actuated by the detection signals from each of the pressure detectors to respectively adjust the pressures of the intermediate stage section, the main steam inlet section and the exhaust section. By balancing the pressure of each of the above parts during warming of the turbine, warming is performed while maintaining the balance of the thrust force and the balance between the forward flow rate and reverse flow rate of the warming steam. It is characterized by the fact that

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 2, reference numeral 30 denotes a high-pressure turbine, to which main steam is supplied through a main steam pipe 31 through a main steam stop valve 32 and a steam control valve 33 during operation. The steam that has performed work in the high-pressure turbine 30 passes through a low-temperature reheat steam pipe 34 and is led to a reheater 35, where it is reheated and then passes through a high-temperature reheat steam pipe 36 to an intermediate-pressure turbine (not shown). will be sent.

By the way, in the intermediate stage part of the high-pressure turbine 30, there is a first warming steam pipe 4 whose one end is connected to a warming steam source 37 and a warming steam inlet pressure control valve 38 and a stop valve 39 are provided in the middle.
0 is connected. Furthermore, a second warming steam pipe 43 having a stop valve 41 and a warming steam outlet pressure control valve 42 is connected to the downstream side of the steam control valve 33 , and a high temperature reheat steam pipe 36
Upstream of the reheat steam stop valve (not shown),
A third warming steam pipe 46 having a stop valve 44 and a warming steam outlet pressure control valve 45 is connected, and one ends of the second and third warming steam pipes 43 and 46 are connected to the condenser 4, respectively.
7 is connected.

Further, the first warming steam pipe 40 is provided with a pressure detector 48, and the high pressure turbine 30 is further provided with a pressure detector 48.
Pressure detectors 4 are also installed in the first stage and exhaust section of the
9,50 are provided. In addition, the reference numeral 5 in the figure
1, 52, and 53 are drain pipes connected to the downstream side of the steam control valve 33, the inlet of the high-pressure turbine, and the low-temperature reheat steam pipe 34, respectively.

The opening of the warming steam inlet pressure regulating valve 38 and the warming steam outlet pressure regulating valve 42, 45 are controlled by pressure detectors 48, 49, 50, respectively, and the pressures of the intermediate stage section, first stage section, and exhaust section of the turbine are controlled. are controlled to have predetermined related pressures.

That is, FIG. 3 is a control block diagram showing an example of a control device for each of the above-mentioned control valves, in which the detection signal from the pressure detector 48 is combined with the setting signal from the first pressure setting device 55 by the comparator 56. and the difference signal is applied to the regulator 57.
The opening degree of the warming steam inlet pressure control valve 38 is controlled by the output signal from the warming steam inlet pressure control valve 38 so that the pressure in the intermediate stage section of the turbine becomes the pressure set by the first pressure setting device 55.

Further, the detection signal of the pressure tester 50 is transmitted to a comparator 58.
, the difference between the setting signal of the first pressure setting device 55 and the setting signal of the second pressure setting device 59 is compared, the deviation signal is applied to the regulator 60, and the output signal from the regulator 60 is The opening degree of the warming steam outlet pressure control valve 45 is controlled by
The pressure is controlled to the pressure set by the pressure setting device 59.

Similarly, the detection signal of the pressure detector 49 is also
1, the difference between the setting signal of the first pressure setting device 55 and the setting signal of the third pressure setting device 62 is compared, and the deviation signal is applied to the regulator 63;
The opening degree of the warming steam outlet pressure control valve 42 is controlled by the output signal from the regulator 63,
The pressure difference between the intermediate stage section and the first stage section of the turbine is controlled to be equal to the pressure set by the third pressure setting device 62.

Therefore, during warming before starting the turbine, the main valves such as the main steam stop valve 32, the steam control valve 33, and the reheat steam stop valve (not shown) are fully opened, and the stop valves 39, 41, 4
Open 4. Then, inside the casing of the high-pressure turbine 30 before warming, each drain pipe 51, 52,
Since it is connected to the condenser 47 through a system such as 53, the pressure is in a vacuum region, and the metal parts are in a cold state, so the signal from the pressure detector 48 is not proportional to the given set pressure. is sufficiently low, the warming steam inlet pressure control valve 38 is opened, and warming steam is supplied from the warming steam source 37 to the intermediate stage section of the turbine. Therefore, for example, if the set pressure of the first pressure setting device 55 is set to 2 atg, the warming steam inlet pressure control valve 38 is kept open until the pressure at the intermediate stage of the turbine reaches 2 atg.

On the other hand, the warming steam that has flowed into the middle stage of the high-pressure turbine 30 sequentially flows to the first stage side and the exhaust side of the turbine, and starts warming the casing and rotor. In this case, both the warming steam outlet pressure regulating valves 42 and 45 do not yet have sufficient pressure on both the main steam inlet side and the exhaust side of the turbine, so the warming steam outlet pressure regulating valve 45 on the exhaust side is set to (2-α ₁ ) It is fully closed until the pressure reaches atg, and the warming steam outlet pressure control valve 42 on the main steam inlet side is also closed (2-α
₂ ) Fully closed until the pressure reaches ATG. In addition,
Here, α ₁ and α ₂ are the set pressures of the second pressure setting device and the third pressure setting device, respectively.

Therefore, when the pressure in the intermediate stage of the turbine rises to 2atg, which is the set pressure of the first pressure setting device,
The warming steam inlet pressure control valve 38 enters a controlled state to maintain the pressure, and the warming steam outlet pressure control valves 42 and 45 control the main steam inlet and exhaust pressures to the above 2atg.
As a result, each steam is controlled and maintained at a lower pressure state by a predetermined pressure, and excess steam is discharged to the condenser through both warming steam outlet pressure control valves 42 and 45. Further, a portion of the steam that has flowed into the turbine casing during this period is deprived of the heat possessed by the steam through contact with low-temperature metals, becomes drain, and is discharged to the condenser 47 through each drain pipe.

In this case, the discharge of the above-mentioned excess steam is necessary and unavoidable to some extent in order to prevent a situation where a large amount of steam is converted into drainage inside the casing, etc., and accumulates inside the casing. However, in the range where thrust bearings are allowed from the viewpoint of energy saving, the warming steam outlet pressure control valves 45 and 4 are controlled by the second and third pressure setting devices 59 and 62.
2 can also be forced to be fully closed.

In this way, the metal temperature of each part increases with respect to the pressure 2atg set by the first pressure setting device 55, and when the pressure approaches the saturation temperature, the setting value of the first pressure setting device 55 is further increased. any value for example
Increase to 4atg. Then, in the same operation as above, 4atg is generated at the warming steam inlet and (4atg is generated at the exhaust side).
-α ₁ )atg, (4-α ₂ )atg on the main steam inlet side
The state of control is maintained. Therefore,
The high-pressure turbine and the like are warmed to the saturation temperature of the 4atg steam.

By gradually changing the set pressure of the first pressure setting device in this way, it is possible to warm up to the target temperature.

FIG. 4 is a diagram showing the relationship between turbine metal temperature and warming steam pressure and time,
The curves shown by broken lines are warming pressure and temperature rise curves in a conventional device, where curve A is the warming steam pressure of the turbine, curve A _I is the turbine internal metal temperature, and curve A _O is the turbine external metal temperature. Further, the curves shown by solid lines are the warming steam pressure and temperature rise curves by the device of the present invention, where curve B is the warming steam pressure of the turbine, curve B _I is the turbine internal metal temperature, and curve B _O is the warming steam pressure of the turbine.
is the turbine external metal temperature.

As can be seen from Fig. 4, in the conventional device, curve A cannot raise the pressure above the specified pressure, and the turbine external metal temperature (curve A _O ) is lower than the turbine internal metal temperature (curve A _I ). There is no other way but to wait for it to follow curve A.
It is not possible to raise the temperature indicated by _O , A _I above the temperature corresponding to the pressure indicated by curve A.

On the other hand, curve B shows that the turbine is warmed up to an arbitrary temperature level as shown in curves B _I and B _O by arbitrarily increasing the setting value of the warming steam pressure while observing the metal temperature status of each part of the turbine. This allows you to increase the warming effect in a short time.

In this way, when the metal temperature of each part rises to the target temperature T℃ and stabilizes, the first
Lower the set pressure of the pressure setting device to the original value, cut off the warming steam to release the pressure inside the turbine, etc., completely disconnect the warming steam system from the turbine drive steam system, and then Thus, warming of the turbine can be completed and preparations can be made for starting the turbine.

By the way, Figure 5 shows the schedule from the start of the steam turbine to reaching the target load, and the relationship between the temperature of the turbine's metal parts (represented by the metal temperature after the first stage) and the steam temperature. The axis shows time and the vertical axis shows temperature.

Thus, the curve T _S shows the main steam temperature from the boiler, and as the load of the turbine or boiler increases, the main steam temperature increases and reaches the rated main steam temperature at a certain intermediate load. Further, the curve T _M shows the change in the representative metal temperature of the turbine due to warming in the conventional device, whereas the curve T _M ' shows the change in the representative metal temperature of the turbine in the case of warming with the device of the present invention. As described above, in the present invention, the temperature of each metal part can be warmed to a higher state before starting the turbine than in the conventional apparatus, so that the starting point of the curve T M _' is higher than the curve T _M.

Therefore, if we assume that the schedule for starting the turbine in the upper stage of FIG. 5 is the same, there are three major differences between curve T _M and curve T _M '.

In other words, the width of the temperature change of the metal part is the curve T
_M is larger than _the curve T
_M is larger than the curve T _M ', and the curve T _M is also larger than the curve T _M ' in terms of the difference between the main steam temperature T _S at startup and the temperature of the metal part. For this reason, the level of thermal stress generated in the turbine during startup of the turbine is much smaller in the case of curve T _M and in the case of curve T _{M '} , that is, in the case of the present invention. I understand that.

In addition, Figure 6 shows the lifetime consumption index of the turbine, which serves as an index for the operation of the steam turbine. Depending on the ratio, there is a relationship as shown in the figure. It should be noted that each value on the curve of the graph represents an index of life consumption, and is a life index consumed per cycle, where starting and stopping of the turbine is considered as one cycle.

As you can see from the graph in Figure 6, if we assume that the lifetime consumption is the same, if the temperature change range of the metal part is large, the temperature change rate needs to be small; If is large, it means that a large amount of life is consumed.

As is clear from the above, if the temperature change width of the conventional device is ΔT, the temperature change width ΔT' of the present invention is smaller than ΔT, resulting in the following effects.

In other words, if the values of the same lifetime consumption rate, for example, 0.03%, are different, in the case of the present invention, the temperature change rate can be set high, and the time from starting the turbine to reaching the target load can be shortened. can. On the other hand, if the temperature rise rate is the same and compared with the conventional technology, if the temperature change width △T' is
It becomes possible to keep the value even lower than 0.03%.

Incidentally, in the above embodiment, the warming steam inlet section is provided in the intermediate stage of the turbine, and this intermediate stage is designed to absorb rotational torque generated in the forward rotation direction due to the flow of warming steam from the inlet to the exhaust side of the high-pressure turbine. A paragraph is selected in which the difference between the rotational torque generated in the reverse direction due to the flow of warming steam from the inlet to the main steam pipe side satisfies the following relationship so that the turning gear will not be dislocated.

｜Forward rotation side torque - Reverse rotation side torque｜
<Required Torque for Turning Disengagement The range that satisfies the above relationship includes the range where the torque on the forward rotation side is smaller than the torque on the reverse rotation side, so it is not a single point but a wide range, and it is possible to select a certain arbitrary paragraph. I can do it. Therefore, if a dedicated entry port is provided in the high-pressure casing as an inlet for warming steam, or if there is a suitable bleeder within the range that satisfies the above relationship, it is possible to use this bleed pipe.

Further, in the above embodiment, the warming steam introduction part is set at one point in the middle stage of the high-pressure casing, but a plurality of parts may be introduced separately into the upper half and the lower half, for example. Furthermore, the flow of the warming steam is reversed to that in the above embodiment, that is, one end of the first warming steam pipe is connected to the condenser for releasing the warming steam, and one end of the second and third warming steam pipes is connected to the condenser. The heating steam may be connected to a warming steam source and the warming steam may be introduced into the high pressure turbine from the warming steam pipe.

Furthermore, the part corresponding to the high-pressure casing may be separated into an ultra-high-pressure part and a high-pressure part as a warming target, but even in this case, it is possible to obtain exactly the same effect by replacing the high-pressure casing with an ultra-high-pressure casing. can.

〔Effect of the invention〕

As explained above, in the present invention, warming steam pipes are connected to the intermediate stage section, the main steam inlet side, and the exhaust section side of the turbine, respectively, and warming steam is introduced from the intermediate stage section and exhausted from the other warming steam pipes. Alternatively, warming steam is introduced from the warming steam pipe connected to the main steam inlet side and the exhaust side and exhausted from the intermediate stage part, and the pressure of the intermediate stage part and the main steam inlet side and exhaust side are Since the pressure relationship is controlled to be constant during warming, the thrust force due to the pressure of the warming steam can be reduced, and the warming steam pressure can be increased. Therefore, the warming steam temperature can be increased accordingly, and even the thick outer surface of the casing can be actively heated, allowing the average temperature to be warmed to a higher level in a shorter time than in the past. be able to. Therefore, the difference between the main steam temperature and the inflowing main steam temperature at the time of startup can be reduced, and thermal stress at the time of turbine startup can be reduced, reducing life consumption and making it possible to start the turbine more safely. Moreover, when the warming steam is introduced from the intermediate stage of the turbine, the turbine is warmed preferentially over the reheater or the like, and the turbine can be warmed efficiently.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an outline of a conventional steam turbine warming device, Fig. 2 is a schematic system diagram of a warming device of the present invention, and Fig. 3 is a block diagram of a control device for warming steam inlet pressure and outlet pressure control valves. Figure 4 is a diagram showing the state of change in warming steam pressure and temperature, Figure 5 is a diagram showing the schedule from the start of the steam turbine to reaching the target load, and a diagram of the relationship between the temperature of the turbine's metal parts and the steam temperature. FIG. 6 is a diagram showing the lifetime consumption index of the turbine. 30... High pressure turbine, 37... Warming steam source, 38... Warming steam inlet pressure control valve, 40... First warming steam pipe, 42...
... Warming steam outlet pressure control valve, 43 ... Second warming steam pipe, 45 ... Warming steam outlet pressure control valve, 46 ... Third warming steam pipe, 48, 49, 50 ... Pressure detector, 5
5...first pressure setting device, 59...second pressure setting device, 62...third pressure setting device.

Claims (1)

[Claims] 1. A first warming steam pipe connected to an intermediate stage of the turbine and having one end connected to a warming steam source or a condenser, and a first warming steam pipe connected to a main steam inlet and an exhaust part of the turbine, respectively. second and third warming steam pipes each having one end connected to a condenser or a warming steam source in correspondence with the first warming steam pipe; an intermediate stage of the turbine; a main steam inlet section and an exhaust section; and each warming steam pipe is actuated by a detection signal from each of the above-mentioned pressure detectors to respectively adjust the pressure of the intermediate stage section, main steam inlet section, and exhaust section. By balancing the pressure of each of the above parts during warming of the turbine, warming can be performed while maintaining the balance of thrust force and the balance between the forward flow rate and reverse flow rate of the warming steam. A steam turbine warming device characterized by: 2. The steam turbine warming device according to claim 1, wherein the first warming steam pipe is a warming steam introduction pipe, and the second and third warming steam pipes are warming steam release pipes. . 3. The steam turbine warming system according to claim 1, wherein the first warming steam pipe is a warming steam relief pipe, and the second and third warming steam pipes are warming steam introduction pipes. Device. 4. The steam turbine warming device according to any one of claims 1 to 3, wherein the second warming steam pipe is connected to the main steam pipe. 5. The steam turbine warming device according to any one of claims 1 to 3, wherein the third warming steam pipe is connected to a boiler reheat steam pipe.