JPS62159704A - Warming up method of steam turbine - Google Patents

Abstract

PURPOSE:To aim at shorten of starting time, by heating the rotor of a steam turbine by direct injection of a steam in the outside system or that in the inside system so that the time required for temperature elevation of the rotor up to a temperature not less than a specified level is shortened. CONSTITUTION:In the case of a high speed warming up operation of a steam turbine, the steam in the outside system supplied from an outside system steam source 8 such as a boiler, etc., passes through steam supply lines 9a, 9b and is supplied into the turbine from steam inlet parts 5, 6, while, the steam introduced into a seal steam header 29 after being subjected to a temperature reduction at a desuperheater 28 is supplied to the final stage portion in the steam turbine through a steam supply line 31 and a pressure control valve 33. And the steam is directly injected to a rotor 2 at the final stage from an air bleeding opening portion 7. By this, the heating of an entire rotor 2 difficult to be performed up to a temperature of not less than the brittle fracture piece transition temperature, can be carried out remarkably quicker than that in a conventional method, thus, quick starting of a steam turbine can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for warming up a steam turbine, and more specifically, to a method for heating a rotor using external steam or internal steam.

<Prior art> When starting a steam turbine that is in a stopped state and operating it, if high-temperature steam is pumped in from the steam inlet from the beginning, the rotor may suffer low-temperature brittle fracture.
Warm-up operation is being carried out because it is dangerous. That is, since the brittle fracture transition temperature of the rotor of a steam turbine is generally about 80° C., warm-up operation is performed until the rotor warms up to above this temperature. Also, when the rotor of a steam turbine is in a stopped state (the rotor is distorted due to its own weight, in order to correct this distortion, a cooling operation is started at a slow rotation speed and performed at the same time).

Therefore, conventionally, after a gearing operation (e.g., 300 to 600 rpm) without supplying steam, steam is fed and the machine is rotated at high speed (e.g., 2,000 to 2,500 rpm).
ml Perform high-speed warm-up operation to warm the rotor above the brittle fracture transition temperature, then perform rated operation (e.g.
3000 to 36'OOr pm).

<Problems to be solved by the invention> However, since the steam outlet side is connected to a condenser and the final stage atmosphere is at a low temperature (about 35°C), the rotor temperature in the final stage cannot be reduced to brittle fracture. It took a considerable amount of time to warm up above the transition temperature. In other words,
The startup time before starting normal operation was quite long (5 to 6 hours).

The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to shorten the time required to start a steam turpino by making it possible to quickly warm up the rotor in the final stage.

Means for Solving Problems> The configuration of the present invention that achieves the above object is characterized in that the rotor of a steam turbine is heated by directly injecting external steam or internal steam to the rotor.

Embodiments FIG. 1 shows a schematic configuration of a steam turbine and its steam supply system to which an embodiment of the present invention is applied.

1 is a casing of the steam turbine, 2 is a rotor supported by the casing 1, 3 is a rotary S blade attached to the rotor 2, and the stationary blade attached to the casing 1 side is not shown.

In addition to the steam inlets 4, 5.6, the casing 1 is provided with an opening (bleeding port or leaked steam recovery port) 7 at the final stage, and in this embodiment, during normal operation, steam is sent to the heater. During start-up operation, steam outside the system or steam inside the system for heating the rotor 2 is injected into the opening 7 through which steam is extracted.

8 is an external steam source such as a boiler, the steam supply #9 is branched into steam supply paths 9a and 9b after passing through a desuperheater 10, and one steam supply path 9a passes through a switching valve 11 and is connected to a steam inlet. Gland seal part 1 between casing 1 and rotor 2 on the side
2 and the steam inlet section 5. The other steam supply path 9b is connected to the steam inlet section 6 via switching valves 13, 14 and a low pressure steam control valve 15. Incidentally, steam supply paths 16, 17, and 18 are connected to the gland seal section 12 to guide steam after being supplied to the seal, and the steam supply path 16 is connected to the steam supply path 16 on the near side of the steam inlet section 6. The steam supply path 17 is connected to a grand seal portion 19 between the casing 1 and the rotor 2 on the steam outlet side, and the steam supply path 18 is connected to a grand condenser 20. In addition, the high pressure steam source 2 in the system
1 is connected to the steam inlet section 4 via a high temperature steam control valve 2.3 by a steam supply $22. The low pressure steam source 24 in the system passes through the switching valve 26 via the steam supply path 25, and then the switching valve 13, 14 and the low pressure steam control valve 1 in the steam supply path 9b.
It is connected between 5 and 5.

On the other hand, the external steam source 8 is connected to a seal steam head 29 via a switching valve 27 and a desuperheater 28, and a steam supply path 30 from the header 29 is connected to the gland seal section 12 on the steam inlet side. It is connected to a steam supply path 17 that connects to a grand seal section 19 on the steam outlet side. Another steam supply path 31 from the header 29 is for supplying steam to the final stage for heating the rotor 2 during startup operation, and is connected to a pressure control valve 3 equipped with a pressure switch 32.
3 to the bleed opening 7.

The pressure control valve 33 is closed by the action of the pressure switch 32 when the pressure in the steam supply path 31 exceeds a certain value. In the figure, 34 is a switching valve, and 35 is a main condenser.

In the steam turbine described above, during high-speed warm-up operation, external steam passes through the steam supply paths 9a and 9b, and is subjected to pressure adjustment 1 and temperature adjustment, respectively, and is supplied into the turbine from the steam inlets 5 and 6. The heated steam that has entered the header 29 further passes through the steam supply path 31 and is pressure-controlled by the pressure control valve 33, and is supplied from the oil opening 7 to the final stage in the steam turbine, where it is fed to the rotor in the final stage. 2 can be sprayed directly. Since the final stage of the rotor 2, which is difficult to heat, is heated by directly injecting steam, the entire loaf 2 can be heated to the brittle fracture transition temperature or higher much more quickly than in the past.

When the rotor 2 is heated above the specified value, the turbine is in normal operation, so as the pressure inside the turbine increases, the pressure inside the steam supply path 31 also increases.
It is detected by the pressure switch 32 and the pressure control valve 33
is closed and the supply of steam for heating is cut off. Of course,
This operation may be performed by manually operating the valve by detecting the end of the rotor 2 or the like.

When the turbine is operated and in-system steam is generated, the out-of-system steam is gradually switched to in-system steam, and finally operation is shifted to only in-system steam.The transition from out-of-system steam to in-system steam is as follows:
This is done by operating the switching valves 1113.14.

As described above, during startup operation, the temperature of the steam supplied to the steam inlets 5 and 6 and the temperature of the steam supplied to the bleed opening 7 are respectively pressure-adjusted, temperature-adjusted, and heated. Care is taken to prevent large temperature differences from occurring in the axial direction of the rotor 2.

Although the steam embodiment uses steam outside the system to heat the final stage of the rotor, steam within the system can be used in the same way.

<Effects of the Invention> According to the method for warming up a steam turbine according to the present invention, external steam or internal steam is directly injected into the final stage of the rotor to heat the rotor. As a result, the startup time is shortened and the steam turbine can be started quickly.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating a steam turbine and its steam supply system to which an embodiment of the steam turbine warm-up method according to the present invention is applied. In the drawing, 1 is a casing, 2 is a rotor, 3 is a rotary blade,
4, 5.6 are steam inlets, 7 is a bleed opening, 8 is an external steam source, and 33 is a pressure control valve.

Claims (1)

[Claims] A method for warming up a steam turbine, the method comprising heating the rotor by directly injecting external steam or internal steam to the rotor of the steam turbine.