JPS5920506A - Turbine bypass device of steam turbine plant - Google Patents

Abstract

PURPOSE:To simplify turbine bypass system by providing a duct which connects a main steam pipe, bypassing a reheater, to a condenser and also providing said bypass duct with a flow rate control valve and a temperature reducer. CONSTITUTION:In a plant which lets steam generated in a boiler 1 pass from a main stop valve 3 successively through a high pressure turbine 4, reheater 7, reheat check valve 9, medium, low pressure turbine 10 so as to make work and drive a generator 11, a high pressure bypass valve 12 is opened at starting time and the steam bypasses to a low temperature reheat pipe 6 through a temperature reducer 13. The second bypass duct C, making the steam in a main steam pipe 2 to bypass the abovementioned reheater 7 and dump in a condenser 16, is provided and a flow rate control valve 17 and a temperature reducer 18 are interposed in the duct C. At a starting time, the residue of steam generated in the boiler 1 is dumped in a condenser 16 through the second bypass conduit C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine bypass device for a steam turbine plant.

The turbine bypass system is used to supply cooling steam to prevent the reheater from overheating when starting the steam turbine plant, to improve startup characteristics by reducing the temperature difference between the steam and the turbine metal, and to reduce the turbine load. This is provided to ensure safety by keeping the pressure rise in the main steam system within a predetermined range when the main steam system is shut off.

FIG. 1 is a principle diagram of a steam turbine plant equipped with a turbine bypass system, and FIG. 2 is an example of a piping diagram of a steam turbine plant equipped with a turbine bypass system in a 600 to 700 MW class coal-fired power plant.

During normal operation, steam generated in the boiler I is introduced into the high-pressure turbine 4 via the main steam pipe 2 and the main stop valve 3 to perform work, and then passes through the check valve 5 and the low-temperature reheat pipe 6 to reheat the boiler. It passes through the heater 7 and is reheated as high-temperature reheat steam into the high-temperature reheat tube 8. It flows into the medium and low pressure turbine 10 through the reheat stop valve 9 and does work.

11 is a generator driven by a steam turbine.

When starting up this steam turbine plant, the reheater 7 may overheat and burn out because steam does not flow to the reheater 7 until steam supply starts to the high pressure turbine 4 and medium and low pressure turbines 10. To prevent this, the high-pressure bypass valve 12 is opened to bypass the steam in the main steam W2 to the low-temperature reheat g6 via the desuperheater 13, and the reheater 7 is stopped. The steam flowing through the reheater 7 cools the reheater to prevent overheating, and is recovered to the condenser 16 via the low temperature bypass valve 14 and the attemperator 15. In this way, while protecting the reheater 7, the metal parts of the high-pressure turbine 4 and the intermediate and low-pressure turbines 10 are heated, and steam is supplied to these turbines, thereby transitioning to power generation operation.

When the external load of the generator 11, which is the load of the steam turbine, is disconnected for some reason, the steam turbine takes on the station load (auxiliary equipment source) and switches to the station independent load operation. In order to prevent an excessive rise in main steam pressure when switching between main steam 'Ii?' and 2
The steam inside the high pressure bypass valve 12. Attemperator 13. Reheater 7. Low temperature bypass valve 14. Condenser 16 via attemperator 15.
dumped into

As described above, the conventional turbine bypass system is configured such that the entire amount of bypass steam flows through the high-pressure bypass circuit A including the high-pressure bypass valve 12 and the entire amount flows through the low-pressure bypass circuit B including the low-pressure bypass valve 14. There is. Therefore, for example, as shown in FIG. 2, if a high voltage bypass circuit A consisting of four lines is provided, the low voltage bypass circuit B must also have a configuration of four lines. Specifically, it is not necessarily limited to the number of series, but it will not work unless the flow rate is set to the same, so if the series have the same capacity, the same number must be installed.

For this reason, the conventional turbine bypass system has a large number of low-pressure bypass circuits B, and the space required for installation is large, resulting in a large building area, all of which are factors that increase equipment costs both directly and indirectly. There is.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a turbine bypass system that can simplify the configuration of a turbine bypass system of a steam turbine plant and reduce the required installation area and equipment cost.

The basic principle of this arrangement is that the flow rate of steam required to flow through the reheater to protect it at the time of startup of a steam turbine plant is the same as that of the steam that flows through the reheater 7 in a conventional turbine bypass system. Considering that approximately 50% of the flow-fit is sufficient, the steam flow rate required to cool and protect the reheater 7 at startup is the same as in the conventional system. The remaining steam is dumped into the condenser 16 via the low temperature bypass valve 14 and the attemperator 15, and the remaining steam is transferred to the reheater 7. The water is bypassed to the water dispenser 16 without passing through the low temperature bypass valve 14 and the desuperheater 15. This reduces the steam r+Lnt of the low-temperature bypass valve 14 by about half, reducing its capacity, required installation area, and equipment cost.

In order to achieve the above object based on the above principle, the present invention provides, in a steam turbine plant equipped with a turbine bypass system, a pipe line that bypasses the reheater and connects the main steam pipe to the water coverer, Further, the above-mentioned bypass line is provided with a flow control valve and a desuperheater.

Next, a typical example of the present invention will be explained with reference to FIGS. 3 and 4.

FIG. 3 shows a principle diagram of a steam tarping rat equipped with an embodiment of the turbine bypass device of the present invention, and is a diagram corresponding to FIG. 1 of the conventional turbine bypass device. When comparing the principle diagram, the device of the present invention (Figure 3)
is different from the conventional system (Fig. 1) in that a second bypass pipe C is provided to bypass the reheater 7 and dump the steam in the main steam pipe 2 to the condenser 16. This is because a flow control valve 17 and a desuperheater 18 are provided in the second bypass pipe line C. FIG. 4 shows an embodiment in which a turbine bypass device is constructed by applying the present invention to a steam turbine plant of a 600 to 700 MW class coal-fired power plant, and is a diagram corresponding to FIG. 2 of the conventional device.

The difference between the device of the present invention (FIG. 4) and the conventional device (FIG. 2) is that, as described in the principle diagram, the fJ2 bypass pipe C has a flow control valve 17 and a desuperheater 18. However, in conjunction with this, the number of series of the high-pressure bypass circuit A' having the high-pressure bypass valve 12 and the desuperheater 13 is reduced, resulting in a two-line configuration, half of the OT future type.

Correspondingly, the number of low-voltage bypass circuits B' is also reduced to two.

During normal operation, the high-pressure bypass valve 12, flow control valve 17, and low-pressure bypass valve 14 are closed to operate in the same manner as a conventional steam turbine plant.

At startup, approximately 50% of the steam generated in the boiler 1 is passed through the high-pressure bypass valve 12 and the desuperheater 13 to the reheater 7 until the metal of the turbine rises in temperature and can start operation. The steam exiting the reheater 7 passes through a low pressure bypass valve 14 and an attemperator 15 and is recovered to a condenser 16. This prevents the reheater 7 from overheating. The remainder (approximately 50%) of the steam generated in the boiler 1 is dumped into the condenser 16 via the flow control valve 17 and the attemperator 18. In this case, the flow rate distribution can be appropriately adjusted by the flow rate control valve 17, and the steam whose temperature has been reduced by the attemperator 18 can be allowed to flow into the condenser 16.

In this way, about 50% of the generated steam passes sequentially through the high-pressure bypass circuit A', the reheater 7, and the low-pressure bypass circuit B' and flows into the condenser 16, and the remaining about 50% flows into the condenser 16. 2
Since it flows directly into the ascites 416 via the bypass 'i# path C, the entire amount of steam generated in the boiler 1 bypasses the high pressure boiler 4 and the medium and low pressure boilers 10 and flows into the condenser 16. Therefore, even when the load on the generator is cut off, excess steam in the main steam pipe 2 is discharged through the above-mentioned route to suppress the pressure increase and it is possible to safely switch to in-house single load operation.

As explained above, when operating the turbine bypass device of the present invention, about 50% of the generated steam can be bypassed to the second bypass line C, so that the high pressure bypass line n% A' and the low pressure bypass line B ' is the capacity of the high pressure bypass line A and the low pressure bypass line a in the conventional device ^1.
It costs about half that of route B.

Compared to FIG. 2 (conventional device t), FIG. 4 (device t of the present invention) omits two high-pressure bypass valves 12 and uses a flow rate control jig.
1 valves 17 are replaced with two thin membranes, the increase or decrease in equipment costs associated with this replacement can be ignored. As a result, the installation cost and space required for the low-pressure bypass system are significantly reduced.

When the present invention is actually applied, the high voltage bypass circuit A'
The ratio between the capacitance of C and the capacitance of the second bypass circuit C is limited to approximately 50% each as in the embodiment shown in FIG.
It can be set appropriately depending on the overall balance of the steam turbine plant.

As explained above, the turbine bypass device of the present invention is provided in a steam turbine plant equipped with a turbine bypass system, in which a reheater is bypassed and a pipe line is provided to connect a main steam pipe to a condenser, and the above-mentioned flow into the bypass pipe of
By providing a t'flil J Mii and a desuperheater,
The configuration of a turbine bypass system of a steam turbine plant, particularly a low-pressure bypass circuit, can be simplified, and the required area and equipment cost can be reduced.

In order to achieve the same object as above based on the basic principle of the present invention described above, namely, to simplify the configuration of the low voltage bypass circuit and reduce the required installation area and equipment cost,
The invention shown in FIG. 3 is improved by providing a passage a which connects the low-temperature heat pipe to the condenser by bypassing the reheater, and includes a flow valve and a flow valve in the bypass pipe. It is also effective to provide a cooking pot.

Fig. 5 shows the principle diagram. Comparing the principle diagram of this improved invention with the four-principle diagram of the conventional device (Fig. 1), the difference is that a third bypass circuit connecting the low-temperature reheat v6 and the condenser 16 is provided, and the above-mentioned third In addition, a flow control valve 19 and a desuperheater 2° were installed in the bypass channel.
Comparing the principle diagram of this improved invention (Fig. 5) with the principle diagram of the specified invention described above (Fig. 3), the main difference is that the second bypass circuit C in the specified invention (Fig. 3)
The starting point of the third bypass line is branched from the main steam pipe 2, whereas the starting point of the third bypass line in the improved invention (FIG. 5) is branched from the low temperature reheat pipe 6.

FIG. 6 is a piping diagram showing an implementation IZIJ of a turbine bypass device of a steam turbine plant constructed by applying the above improved invention to a 600 to 700 MW class coal-fired power plant. In the embodiment of this improved invention (FIG. 6), the high-pressure bypass circuit A has a 4-line structure similar to the conventional device (FIG. 2), but approximately 50% of the steam flow rate flowing through this high-pressure bypass circuit A is % directly to the condenser 16, the third pipe pass circuit with the condensation control valve 19 and the desuperheater 20 is connected to the reheating J7
A low pressure nozzle (47
It is sufficient that the 57 circuit B' has a two-channel structure as in the above-mentioned specific invention (FIG. 4).

In the Tahin bypass device N of the improved invention (FIG. 6) configured as described above, during normal operation fd high pressure bypass valve 12. Flow t 匍1 ffi+1 valve 19 and low pressure (
The inox valve 14 can be closed and operated as in the prior art system (FIG. 2). At startup, the high pressure bypass valve 12 and the low pressure bypass valve 14 are opened,
In addition, the flow rate control valve 19 is adjusted to adjust the flow rate of the third bypass channel, and only the A airflow ridge, which is necessary for cooling the reheater 7, of the steam flowing through the high-pressure bypass circuit A is regenerated. Heater7. Low pressure bypass valve 14. It flows into the condenser 16 via the attemperator 15, and the remaining steam flow flows into the condenser 16 through the third bypass line.

Further, by the same operation as described above, it is also possible to suppress the pressure increase in the main steam pipe 2 when changing over to in-house single load/military transfer.

In the embodiment of the improved invention described above (FIG. 6), the steam condition in the high temperature reheat tube 8 is 50 atg.566C, while the steam condition in the low temperature reheat tube 6 is 50 atg.
・It is 300C. Accordingly, the flow rate control valve 19 provided by applying the present improved invention can be made of a material with lower heat resistance than the low-pressure bypass valve 14, which can be partially omitted by applying the present improved invention. It is possible to reduce equipment costs.

As described in detail above, the turbine bypass device of the present improved invention is provided in a steam turbine plant equipped with a turbine bypass system, by providing a pipe line that connects the low-temperature reheat pipe to the condenser by bypassing the reheater, In addition, by providing a flow control valve and a desuperheater in the bypass pipeline, the structure of the turbine bypass system of a steam turbine plant can be simplified and the required installation area and installation cost can be reduced, which is an excellent practical effect. arise.

[Brief explanation of drawings]

What about figure 1? jt Principle diagram of a steam turbine plant equipped with a turbine bypass device 6, Fig. 2 is 600-700
A steam system configuration diagram of a mA methane plant equipped with a conventional MW-class turbine bypass device, FIG. 3 is a principle diagram of a steam turbine plant equipped with an embodiment of the turbine bypass device of the present invention, and FIG. Figure 5 shows a steam system and system configuration diagram of a ~700 MW class steam turbine plant equipped with an embodiment of the turbine bypass device of the present invention. The principle diagram, Figure 6, shows a 600-700M turbine equipped with an example of the turbine bypass device of the above-mentioned improved engine W4.
It is a steam system configuration diagram of a W-class steam turbine grater. 1... Boiler, 2... Main steam pipe, 3... Main blocking valve, 4... High pressure turbine, 5... Check valve, 6... Low tM N heat a17... Reheater, 8...high temperature reheat α,
10... Medium, low pressure turbine, 12... High pressure bypass valve, 13, 15, 18° 20... Desuperheater, 14...
Low pressure bypass valve, 16... Condenser, 17.19...
Flow rate control] Wholesale valve. Agent Patent Attorney Masami Akimoto

Claims (1)

[Claims] 1. In a steam turbine plant equipped with a turbine bypass system, a pipe line is provided that connects the main steam pipe to the condenser by bypassing the reheater, and a flow rate is provided in the bypass pipe. A turbine bypass device for a steam turbine plant, characterized by being provided with a control piece and a desuperheater. 2. A steam plant equipped with a turbine bypass system (in a turbine plant, a pipe is provided to bypass the reheater and connect the low-temperature reheat pipe to the condenser, and a flow control valve and a reducer are installed in the bypass pipe). A turbine bypass device for a steam turbine plant, characterized by being equipped with a warmer.