JPH0751887B2 - Turbin overspeed suppression system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for introducing turbine inlet steam of a power plant directly into a condenser, and in particular, shuts off supply steam accompanying emergency disconnection of turbine load ( The present invention relates to a turbine overspeed suppressing system suitable for suppressing an increase in turbine rotational speed when a trip occurs.

[Prior Art] FIG. 3 shows a configuration of a turbine cycle of a boiling water nuclear power plant as an example of a conventional turbine overspeed suppression system.

The steam generated in the reactor vessel 1 passes through the main steam pipe 2, the main steam header 3 and is supplied to the high pressure turbine 7 through the main steam stop valve 4, the steam control valve 5 and the high pressure turbine inlet pipe (lead pipe) 6. Do the work. The steam that has worked in the high-pressure turbine 7 passes through the cross-around pipe 8, the moisture in the steam is removed by the moisture separator 9, and the low pressure is passed through the combination intermediate valve 10, the accept valve 11, and the low-pressure turbine inlet pipe 12. After being supplied to the turbine 13 to perform work, it is cooled in the condenser 14, and as condensate is sucked out of the condenser 14 by the condensate pump 15, and is supplied by the low-pressure feed water heaters 16 and 17. After the temperature is raised, it is further raised by the feed water pump 18, raised by the high-pressure feed water heaters 19 and 20, and returned to the reactor vessel 1 again.

On the other hand, to the high-pressure feed water heaters 19 and 20 and the low-pressure feed water heaters 16 and 17, steam extracted from the outlet of the high-pressure turbine 7 or an intermediate paragraph of the turbine is supplied to the extraction pipes 21 and 21 for heating the feed water and the condensed water. 2
Introduced via 2, 23, 24 and bleed check valves 26, 27, 28, 29.

Furthermore, when a turbine trip occurs, the main steam stop valve 4, the steam control valve 5 installed at the inlet of the high pressure turbine 7, and the combination intermediate valve 10 and the accept valve 11 installed at the inlet of the low pressure turbine 13 are Since it is closed, the steam supply to the turbine is cut off.

At this time, the bleed check valves 25, 26, 27, 28 are also closed to prevent the turbine from overspeeding due to the drain flush of the low-pressure feed water heaters 16, 17 and the high-pressure feed water heaters 19, 20. on the other hand,
After the turbine trip, a steam turbine bypass pipe 29 sent from the main steam header 3 via the main steam pipe 2 in order to reduce the reactor pressure increase due to the interruption of the flow path to the turbines 7 and 13. After being passed through the turbine bypass valve 30, it is directly guided to the condenser 14, and after being condensed in the condenser 14, it is sent to the reactor vessel 1 again.

Note that, as known techniques relating to this type of apparatus, there are, for example, JP-A-55-3197 and JP-A-55-48699.

[Problems to be solved by the invention]

In the above-mentioned prior art, when the turbine trips, the main steam stop valve 4, installed at the inlet of the high pressure turbine 7,
The steam control valve 5, the combination intermediate valve 10 and the accept valve 11 installed at the inlet of the low-pressure turbine 13 are closed. At this time, bleed check valves 25, 26, 27, 28 are installed to prevent overspeed of the turbine due to drain flush in the low-pressure feed water heated air 16, 17 and the high-pressure feed water heater 19, 20. However, the high pressure turbine inlet pipe 6, the low pressure turbine inlet pipe 12, the extraction pipes 21,2
The residual steam inside the 2,23,24 high-pressure turbine 7 and the low-pressure turbine 13 may cause the turbine to overspeed. Further, in order to reduce the residual energy of the internal steam in the pipe, the main steam stop valve 4, the steam control valve 5, the combination intermediate valve 1
0, the accept valve 11 and the bleed check valve 25, 26, 27, 28 had to be constrained in the layout design, which made the layout design difficult.

The object of the present invention is to reduce the internal steam residual energy, which is a factor of turbine overspeed, enables the removal of the extraction check valve, relaxes the constraint conditions of the layout design, and It is to obtain a turbine overspeed suppression system that can improve reliability.

[Means for solving problems]

The basic principle of the present invention created to achieve the above object will be briefly described below. In the present invention, the residual internal steam energy of the high-pressure turbine inlet pipe 6, the low-pressure turbine inlet pipe 12, the extraction pipes 21, 22, 23, 24, the high-pressure turbine 7, and the low-pressure turbine 13, which causes turbine overspeed, is reduced.

Particularly, the internal steam residual energy of the high-pressure turbine inlet pipe 6, the low-pressure turbine inlet pipe 12, the high-pressure turbine 7 and the low-pressure turbine 13 is 70% or more of the whole, which reduces the internal steam residual energy and reduces the turbine excess energy. Prevent speed.

In order to prevent turbine overspeed to a sufficient extent for practical use, the present inventor is able to prevent turbine overspeed by extracting the internal steam residual energy from a portion that accounts for 70% or more of the internal steam residual energy. I paid attention.

In addition, it is considered appropriate to introduce the residual energy of the internal steam into the condenser that has a negative pressure even during turbine bypass operation.

In order to achieve the above-mentioned object (prevention of overrunning at the time of trip) based on the above-mentioned principle, the system according to the present invention is a power generation plant provided with a steam generator, a steam turbine and a condenser, and the steam It is characterized in that a pipeline for supplying steam to the turbine and the condenser are connected by a pipe provided with a valve.

[Action]

According to the suppression system configured as described above, the valve is opened, the high temperature and high pressure steam in the side pipe of the steam turbine is introduced into the condenser to remove energy, and the tripped steam turbine Overrunning can be prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is an overall system diagram in this embodiment, and FIG. 2 is a detailed extraction diagram of the same.

The difference from the conventional system configuration (FIG. 3) is that the high-pressure turbine inlet pipe 6 is branched to provide the high-pressure turbine bypass pipe 34 and the high-pressure turbine bypass valve 32, and further the low-pressure turbine inlet pipe 12 is branched. That is, the low-pressure turbine bypass pipe 35 and the low-pressure turbine bypass valve 33 are provided.

When carrying out the present invention, it is possible to minimize the internal steam residual energy of the high pressure turbine inlet pipe 6, the high pressure turbine 7, the low pressure turbine inlet pipe 12, the low pressure turbine 13, and the extraction pipes 21, 22, 23, 24. desirable. In this embodiment, the main steam stop valve 4, the steam control valve 5, the combination intermediate valve 10, the accept valve 11, and the extraction check valves 25, 26, 27, 28 are provided in the vicinity of the turbine to shorten the length of the installation. , The internal steam residual energy is reduced.

However, it may be very difficult to provide the valve in the vicinity of the turbine because of the arrangement plan and the piping route plan. Particularly in recent nuclear power plants, in order to reduce the building space, as shown in FIG. 4, low pressure feed water heating 16, 17 is built in the condenser 14, and the installation position of the extraction check valve is It is fixed. However, the present invention is applied to introduce the internal steam residual energy in the vicinity of the turbine from the high-pressure turbine inlet pipe 6 to the condenser 14 via the high-pressure turbine bypass pipe 34 and the high-pressure turbine bypass valve 32, and at the same time, to the low-pressure turbine inlet pipe. 12 internal steam residual energy from the low pressure turbine inlet pipe 12 to the low pressure turbine bypass pipe
When introduced into the condenser 14 via the low pressure turbine bypass valve 35 and the low pressure turbine bypass valve 33, residual steam internal energy in the vicinity of the turbine is reduced, and it is not necessary to provide check valves in the extraction pipes 23 and 24.
Since the check valve can be omitted, the manufacturing cost can be reduced, and the design constraint can be reduced to facilitate the design.

In the present embodiment (FIG. 1), the hydraulic control device 31 operates during the turbine trip and the main steam stop valve 4, the steam control valve 5,
The combination intermediate valve 10 and the accept valve 11 are closed. Further, the hydraulic control device 31 is activated by the signal of the turbine trip, and the turbine bypass valve 30 is fully opened in about 0.3 seconds.

On the other hand, the overspeed of the turbine in the conventional device becomes maximum about 3 seconds after the turbine trip, and therefore the hydraulic control device 31 is operated by the signal of the turbine trip (as in the turbine bypass valve 30 described above). ) High-pressure turbine bypass valve
By fully opening 32 and the low-pressure turbine bypass valve 33, it is possible to prevent the turbine from overspeeding. That is, since the turbine bypass pipe and the turbine bypass valve are provided in both the high-pressure turbine and the low-pressure turbine as described above, the residual energy of steam in the high-pressure turbine and the low-pressure turbine during the turbine trip can be reduced and the high-pressure turbine can be reduced. Both the low pressure turbine and the low pressure turbine can prevent overspeed. By further reducing the residual energy of steam in the low-pressure turbine, the following effects are obtained.

(A) The extraction check valve for preventing flush steam of the low-pressure feed water heater can be deleted.

(B) Especially in recent nuclear power plants, since low pressure feed water heating is built in the condenser, the extraction check valve can be removed to allow the extraction pipe to be processed in the condenser, and the extraction pipe with a large diameter can be used. Can be reduced by about 30%, which reduces equipment costs and saves space.

(C) Further, since the extraction pipe can be treated in the condenser, the number of large-diameter condenser seats is reduced, the leak potential is alleviated, and the reliability is improved.

It has an effect.

〔The invention's effect〕

As described above, when the turbine overspeed suppression system of the present invention is applied, when the steam turbine of the power generation plant trips, overspeed of the steam turbine can be prevented.

[Brief description of drawings]

FIG. 1 is a system diagram of a power plant in which an embodiment of a control system according to the present invention is provided, FIG. 2 is a system diagram of a turbine bypass device in the above embodiment, and FIG. 3 is a system diagram of a conventional power plant. FIG. 4 is an explanatory diagram of a configuration of a conventional condenser. 1 ... Reactor pressure vessel, 2 ... Main steam pipe, 3 ... Main steam header, 4 ... Main steam stop valve, 5 ... Steam control valve, 6 ...
High pressure turbine inlet pipe, 7 High pressure turbine, 8 Crossover pipe, 9 Moisture separator, 10 Combination intermediate valve, 11 Accept valve, 12 Low pressure turbine inlet pipe, 13 … Low pressure turbine, 14 …… Condenser, 15 …… Condenser pump, 16 …… Low pressure water heater, 17 …… Low pressure water heater, 18 …… Water pump, 19 …… High pressure first water heater , 20
...... High pressure second feed water heater, 21 ...... First extraction pipe, 22 ...... Second extraction pipe, 23 ...... Third extraction pipe, 24 ...... 4th extraction pipe, 25 ...
… First bleed check valve, 26 …… Second bleed check valve, 27 …… Third
Bleed air check valve, 28 ...... 4th bleed air check valve, 29 ...... Turbine bypass pipe, 30 ...... Turbine bypass valve, 31 ...... Hydraulic control device, 32 ...... High pressure turbine bypass valve, 33 ...... Low pressure turbine bypass Valve, 34 ... High-pressure turbine bypass pipe, 35 ...
… Low-pressure turbine bypass pipe, 36 …… Low-pressure first feed water heater, 37 …… Low-pressure second feed water heater.

Claims (1)

[Claims] 1. In a turbine overspeed suppressing system in a power plant having a steam generator 1, a high-pressure turbine 7, a low-pressure turbine 13, and a condenser 14, steam generated by the steam generator 1 is supplied to the high-pressure turbine 7. Main steam stop valve 4 provided on the main steam pipe 2 leading to the low pressure turbine inlet pipe 12 leading the steam discharged from the high pressure turbine 7 to the low pressure turbine 13 Valve 10, accept valve 11, main steam stop valve 4, high pressure turbine bypass pipe 34 for branching steam from the high pressure turbine inlet pipe 6 downstream of the steam control valve 5 to the condenser 14, and the high pressure turbine A high-pressure turbine bypass valve 32 provided on the bypass pipe 34, and a low-pressure turbine bypass for branching steam from the low-pressure turbine inlet pipe 12 on the steam downstream side of the combination intermediate valve 10 and the accept valve 11 to the condenser 14. The pipe 35, the low-pressure turbine bypass valve 33 provided on the low-pressure turbine bypass pipe 35, the main steam stop valve 4, the steam control valve 5, the combination intermediate valve 10, and the accept valve 11 when the turbine trip is detected. A control device 3 that closes and fully opens the high pressure turbine bypass valve 32 and the low pressure turbine bypass valve 33.
Turbine overspeed suppression system characterized by including 1.