JPH0913909A - Warming device for steam turbine - Google Patents

Abstract

PURPOSE: To shorten the time required for starting a turbine by more effectively warming up an outer casing and an inner casing. CONSTITUTION: An inlet sleeve 4 is directly connected to an inlet steam pipe 1 via no contact section with an outer casing 2 made of low-Cr steel. The inlet steam pipe 1 is integrated with the outer casing 2 at a weld section 5. A steam passage 9 is formed around the portion of the inlet sleeve 4 inserted into an inner casing 3, and an warming steam inlet 10 is bored on the inlet steam pipe 1 to be communicated with the steam passage 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine, and more particularly to a steam turbine warming device suitable for quickly warming up an outer casing and an inner casing and shortening start-up time.

[0002]

2. Description of the Related Art In a thermal power plant to cope with global environmental problems, one of the most important challenges to be addressed is the improvement of power generation efficiency resulting in a reduction in fossil fuel usage. Even in the steam turbine, in order to improve turbine efficiency, the turbine inlet steam condition is set to a higher temperature,
It is required to increase the pressure.

With respect to the steam temperature at the turbine inlet, 538 ° C to 566 ° C class has been the mainstream in the conventional steam turbine, but recently, 593 ° C class which exceeds the above temperature has been put into practical use, and 600 ° C in some cases. A super class is also planned.

FIG. 6 shows an example of a reheat steam inlet of a conventional steam turbine. The reburnt steam flowing from the inlet steam pipe 1 is guided to the inner casing 3 through the inlet sleeve 4 connecting the outer casing 2 and the inner casing 3, and flows into a nozzle (not shown). In the figure, reference numeral 5 indicates a welded portion between the inlet steam pipe 1 and the outer casing 2.

[0005]

As described above, the conventional turbine inlet steam temperature is 538 ° C to 566 ° C.
For example, the inlet steam pipe 1, the outer casing 2, and the inner casing 3 can usually be made of low Cr steel capable of ensuring a sufficient mechanical strength at the above temperature. However, when the steam temperature rises to 593 ° C., the low Cr steel cannot be used as it is because of the decrease in mechanical strength.

[0006] In particular, when the outer casing 2 has such a structure that the high-temperature steam is directly contacted with it, the mechanical strength is remarkably lowered, and an effective measure for preventing this is required. By the way, since the entire inner surface of the inlet steam pipe 1 and the inner casing 2 is in direct contact with high temperature steam, high Cr steel excellent in securing strength at high temperature is used.

Generally, the high Cr steel has a smaller heat transfer coefficient than the low Cr steel, the heat transfer becomes slower when heated by steam, and the linear expansion coefficient is different between the two. There is a difference. Normally, when starting a steam turbine, it is necessary to warm up to protect turbine components,
This is done as follows. That is, as shown in FIG. 7, a part of the low-temperature ground steam is extracted as warming steam into the warming steam pipe 6, and this flows into the inlet conduit 7 in the upper half of the outer casing 2, and the sleeve 8
Through the inner casing 3. The low-temperature steam gradually heats the outer casing 2, the inner casing 3, the rotor (not shown), etc., so that the high-temperature steam directly touches the metal surface in the cold state to rapidly heat the member, It is possible to prevent generation of excessive thermal stress.

However, in the method of introducing such low-temperature ground steam as warming steam, it takes time until the temperature of the outer casing 2, the inner casing 3 and the like rises to a predetermined temperature, and in particular, the high thermal conductivity is small. Since it takes a long time for the Cr steel to reach a predetermined temperature, the starting time is prolonged.

On the other hand, since the inner surface of the inner casing 3 is warmed up, the outer casing 2 located on the outer side of the inner casing 3 is warmed up.
Warming steam does not flow directly to the outer casing 2
It takes a longer time to reach a predetermined temperature.

An object of the present invention is to provide a warming device for a steam turbine, which can warm up the outer casing and the inner casing more effectively.

[0011]

SUMMARY OF THE INVENTION The present invention is a steam turbine configured to direct steam from an inlet steam pipe through an inlet sleeve and into an inner casing, wherein a space between the outer casing and the inner casing is provided around the inlet sleeve. Is formed, and a steam inlet for taking in warming steam is provided in the inlet steam pipe so as to communicate with the steam passage.

Another invention is directed to a steam turbine configured to guide steam from an inlet steam pipe through an inlet sleeve to a nozzle box in an inner casing.
A steam passage communicating with a space between the outer casing and the inner casing is formed around the inlet sleeve, and a steam inlet for introducing warming steam is provided in the inlet steam pipe so as to communicate with the steam passage. To do.

[0013]

According to the present invention, together with the conventional warning system, another warning system for directly heating the inner surface of the outer casing and the outer surface of the inner casing is constructed. The waving steam that leads to this wing system flows into the steam passage around the inlet sleeve from the steam inlet formed in the inlet steam pipe, and then flows from there to the space between the outer casing and the inner casing. The wing steam heats the outer casing from the inner surface and further heats the inner casing from the outer surface. In addition to heating from the inner surface of the inner casing, the temperature rises in a short time due to direct heating from the outer surface. The temperature of the outer casing also rises in a short time due to direct heating from the inner surface. In this way, the temperature of both casings reaches a predetermined warming temperature, and warm-up can be completed quickly.

[0014]

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

FIG. 1 shows the reheated steam inlet. The inlet sleeve 4 is directly connected to the inlet steam pipe 1 without any contact portion with the outer casing made of low Cr steel. The inlet steam pipe 1 is integrated with the outer casing 2 at the weld 5. An inlet conduit 7 is provided in the upper half of the outer casing 2, and a sleeve 8 is provided at the tip of the warming inlet steam pipe 7 through the outer casing 2 and the inner casing 3. Further, a steam passage 9 is formed around the inlet sleeve 4 except for a portion inserted into the inner casing 3, and a warming steam inlet 10 is formed in the inlet steam pipe 1 so as to communicate with the steam passage 9. ing. In the figure, reference numeral 4a indicates a fin formed on the inlet sleeve 4.

Next, the operation of the above configuration will be described with reference to FIG.
A description will be given with reference to FIG.

The auxiliary steam header 11 before starting is supplied with steam from a boiler or an auxiliary boiler (not shown), and the pressure of this auxiliary steam is 10 to 20 kg / cm ² g,
The temperature is about 200 ° C to 300 ° C. When warming up the intermediate-pressure turbine, the auxiliary steam is adjusted to a pressure suitable for warming steam by the control valve 12 and guided to the inlet conduit 7 through the warming steam pipe 13. This warming steam flows from the inlet conduit 7 through the sleeve 8 into the inner casing 3.

This warming steam is divided into one that flows into the inlet steam pipe 1 through the inlet sleeve 4 and one that flows to the turbine exhaust side, and heats the inner casing 3 from the inner surface.

On the other hand, the branch pipe 1 of the warming steam pipe 13
The warming steam flowing in 4 flows into the steam passage 9 through the warming steam inlet 10 of the inlet steam pipe 1, and further flows into the space between the outer casing 2 and the inner casing 3. The warming steam heats the outer casing 2 from the inner surface and further heats the inner casing 3 from the outer surface.

In addition to the heating from the inner surface according to the conventional technique, the temperature of the inner casing 3 rises in a very short time due to the heating from the outer surface, and quickly reaches a predetermined warming temperature. The temperature of the outer casing 2 also rises in a short time due to direct heating from the inner surface, and this also reaches a predetermined warming temperature. After that, part of the warming steam that has heated the outer casing 2 and the inner casing 3 and has dropped in temperature becomes medium pressure turbine exhaust and flows to a low pressure turbine (not shown), and the warming steam of the outer casing 2. The exhaust pipe 16 is divided into the one that flows to the outlet 15.
Through a condenser (not shown).

As described above, in this embodiment, the inlet steam pipe 1 made of high Cr steel is used by using the auxiliary steam having a relatively high temperature.
And the inner casing 3 and the outer casing 2 made of low Cr steel can be quickly warmed up to a predetermined temperature,
It is possible to significantly reduce the time required for starting the turbine.

Further, another embodiment will be described with reference to FIG. FIG. 3 shows the main steam inlet of the steam turbine. The inlet steam pipe 21 for guiding the main steam is an outer casing 22.
It is integrally connected to by welding. The main steam path between the outer casing 22 and the inner casing 23 is constituted by an inlet sleeve 24 that penetrates both casings 22, 23. A nozzle box 25 is provided inside the inner casing 23, and the tip of the inlet sleeve 24 is connected to the steam chamber of the nozzle box 25. Further, the steam passage 2 is provided around the inlet sleeve 24.
6 is formed, and a warming steam inlet 27 is bored in the inlet steam pipe 21 so as to communicate with the steam passage 26. In the figure, reference numeral 24a is an inlet sleeve 24.
It shows the fins formed on the.

Next, the operation will be described with reference to FIG. 4 together with FIG.

When warming up the high-pressure turbine, the auxiliary steam in the auxiliary steam header 11 is adjusted by the control valve 12 to a pressure suitable for warming steam, and the warming steam pipe 13
a through warming steam inlet 27 of inlet steam pipe 21
It is led to. The warming steam enters the steam passage 26 around the inlet sleeve 24 from the warming steam inlet 27, and further flows into the space between the outer casing 22 and the inner casing 23 to make the outer casing 22 from the inner surface and further to the inner casing. 23 is heated from the outside respectively.

Separately from this, the auxiliary steam in the auxiliary steam header 11 is guided to the high-pressure exhaust pipe 30 through the warming steam pipe 13b. This warming steam flows into the space between the outer casing 22 and the inner casing 23 from the high-pressure exhaust pipe 30, and the outer casing 22 from the inner surface,
Further, the inner casing 23 is heated from the outside. In addition to the warming steam from the turbine exhaust port side, direct heating by the warming steam from the turbine inlet side causes the inner casing 23 and the outer casing 22 to reach a predetermined warming temperature in a short time.

After that, the warming steam that has heated and cooled the outer casing 22 and the inner casing 23 flows to the warming steam outlet 31 and is collected in the condenser through the exhaust pipe 16.

As described above, also in this embodiment, the inlet steam pipe 21 and the inner casing 23 made of high Cr steel and the outer casing 22 made of low Cr steel are quickly warmed to a predetermined temperature by using the auxiliary steam having a relatively high temperature. Can be machined.

Further, a different embodiment will be described with reference to FIG.

A communication hole 28 for warming steam is formed in the inlet sleeve 21. This communication hole 2
8 is penetrated through the wall surface of the main body so as to connect the steam passage 26 and the inside of the inlet sleeve 24.

In the structure described above, the warming steam extracted through the communication hole 28 heats the inlet sleeve 24 from the inner surface. Further, the warming steam heats the nozzle box 25 and the inner casing 23 from the inner surface. As a result, the high-temperature warming steam from the auxiliary steam header 11 is supplied to the nozzle box 2
Since 5 and the inner casing 23 are heated from the outer surface at the same time as heating from the outer surface, these turbine components can be warmed up more effectively.

Therefore, also in this embodiment, the time required at the time of starting the turbine can be greatly shortened.

[0032]

As described above, according to the present invention, the steam passage communicating with the space between the outer casing and the inner casing is formed around the inlet sleeve, and the steam passage is communicated with the steam passage to warm the inlet steam pipe. Since the steam inlet is provided, the outer casing and the inner casing can be warmed up in an extremely short time. Therefore, according to the present invention, it is possible to significantly reduce the time required to start the turbine.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a steam turbine warming device according to the present invention.

FIG. 2 is a system diagram showing a flow of warming steam according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a system diagram showing the flow of warming steam according to the present invention.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a reheat steam inlet of a conventional steam turbine.

FIG. 7 is a system diagram showing a flow of warming steam according to a conventional technique.

[Explanation of symbols]

 1 inlet steam pipe 2, 22 outer casing 3, 23 inner casing 4, 24 inlet sleeve 9, 26 steam passage 10, 27 warming steam inlet 25 nozzle box

Claims (3)

[Claims] 1. A steam turbine configured to guide steam from an inlet steam pipe into an inner casing through an inlet sleeve, the steam passage leading to a space between the outer casing and the inner casing around the inlet sleeve. And a steam inlet for taking warming steam into the inlet steam pipe so as to communicate with the steam passage. 2. A steam turbine configured to direct steam from an inlet steam pipe through an inlet sleeve to a nozzle box in the inner casing, wherein the space around the inlet sleeve leads to a space between the outer casing and the inner casing. A steam turbine warming device, wherein a steam inlet for introducing warming steam is provided in the inlet steam pipe so as to communicate with the steam passage. 3. The warming device for a steam turbine according to claim 2, wherein a communication hole is formed in the inlet sleeve through the wall surface of the main body.