JP2003148111A - Steam turbine plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce capacities (diameters) of high and low pressure turbine bypass valves and bypass piping, and also to reduce boiler fuel consumption during turbine stoppage in a steam turbine plant carrying out high and low pressure turbine bypass operations. SOLUTION: The steam turbine plant is provided with a boiler for generating steam provided with a reheater, plural stages of steam turbines respectively leading in steam of different pressures and driving a generator, and a condenser cooling and condensing the steam. It is composed so that the high and low pressure turbine bypass operations are carried out at starting. A first operation mode used at starting and a second operation mode selectively used after full admission in the first operation mode are provided in opening control of a reheat steam control valve controlling a steam quantity fed from the reheater to a low pressure turbine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine plant that performs high and low pressure turbine bypass operation at startup.

[0002]

2. Description of the Related Art A conventional steam turbine plant configuration example is shown in FIG. 10 and will be briefly described. In FIG. 10, reference numeral 1 in the drawing is a boiler, 2 is a reheater, 3 is a generator, 4 is a high pressure turbine, 5 is a low pressure turbine, 6 is a condenser, 7 is a control unit, 8 is a condensate pump, 9 is a spray water line, 10 is a spray water control valve. The steam generated in the boiler 1
It is guided to the high-pressure turbine 4 through the main steam pipe 11. A steam control valve 12 is provided in the main steam pipe 11, and the amount of steam supplied to the high-pressure turbine 4 is adjusted by controlling the opening degree of the steam control valve 12 according to the power generation load. The steam that has worked in the high-pressure turbine 4 is guided to the reheater 2 through the low-temperature reheat steam pipe 13.

The steam reheated by the reheater 2 is guided to the low pressure turbine 5 through the reheat steam pipe 14. Reheat steam pipe 1
4 is provided with the reheat steam control valve 15 that controls the opening degree in conjunction with the opening degree control of the steam control valve 12 described above, the reheat steam depending on the opening degree of the reheat steam control valve. The quantity will be supplied to the low pressure turbine 5. The reheated steam thus supplied to the low-pressure turbine 5 works as a drive source of the low-pressure turbine 5, and is then sent to the condenser 6 to be condensed.

The main steam pipe 11 and the low temperature reheat steam pipe 13 are connected by a high pressure steam bypass pipe 17 having a high pressure turbine bypass valve 16. The high-pressure steam bypass pipe 17 allows an excess amount of steam to flow directly to the low-temperature reheat steam pipe 13 in accordance with the operating condition of the high-pressure turbine 4, and the high-pressure steam bypass pipe 17 keeps the detected value of the pressure sensor 18 at a predetermined pressure. The opening degree of the turbine bypass valve 16 is controlled. A low pressure steam bypass pipe 20 having a low pressure turbine bypass valve 19 is connected between the reheat steam pipe 14 and the condenser 6. This low-pressure steam bypass pipe 20 is used for the low-pressure turbine 5
The surplus steam amount is caused to flow directly to the condenser 6 in accordance with the operating conditions of the above, and the opening degree control of the low pressure turbine bypass valve 19 is performed so as to maintain the detected value of the pressure sensor 21 at a predetermined pressure.

In the steam turbine plant having the above-described structure, at the time of start-up, an operation operation called a high / low pressure turbine bypass operation described below is performed from before steam aeration until 100% load is reached. In the first stage of this high and low pressure turbine bypass operation (before steam ventilation), all of the steam generated in the boiler 1 (excluding atmospheric emission and boiler auxiliary steam) is transferred from the main steam pipe 11 to the high pressure steam bypass pipe 1.
The reheated steam reheated in the reheater 2 is introduced from the reheated steam pipe 14 into the condenser 6 through the low pressure steam bypass pipe 20. That is, since the steam generated in the boiler 1 does not have sufficient temperature and pressure for the operation of the steam turbine, the steam control valve 12 and the reheat steam control valve 15 are fully closed and the high pressure turbine 4 and the low pressure turbine are closed. 5 is bypassed and sent to the condenser 6.

In the second stage of high / low pressure turbine bypass operation (steam ventilation-steam co-entry), the steam generated in the boiler 1 is partly controlled by controlling the opening degree of the steam control valve 12 and the reheat steam control valve 15. The high pressure turbine 4 and the low pressure turbine 5 are ventilated to raise the temperature of the steam turbine. At the third stage of high / low pressure turbine bypass operation (combining steam to reach first low load), the high pressure turbine bypass valve 16 is fully closed,
The entire amount of steam generated in the boiler 1 (excluding atmospheric emission, boiler auxiliary steam, etc.) is guided to the high-pressure turbine 4 from the main steam pipe 11. The reheated steam that has passed through the reheater 2 is guided to the low pressure turbine 5 by controlling the opening degrees of the reheated steam control valve 15 and the low pressure turbine bypass valve 19.

In the fourth stage of high / low pressure turbine bypass operation (first low load to second low load), the high pressure turbine bypass valve 16 is fully closed, and the total amount of steam generated in the boiler 1 (release to the atmosphere and (Excluding boiler auxiliary steam) is introduced from the main steam pipe 11 to the high-pressure turbine 4. The reheated steam that has passed through the reheater 2 has the reheated steam control valve 15 fully opened and the low-pressure turbine bypass valve 19 fully closed. All but the reheated steam introduced to 6 is introduced to the low pressure turbine 5.

In the final stage 5 of high and low pressure turbine bypass operation (second low load to 100% load),
In addition to the high-pressure turbine bypass valve 16 and the low-pressure turbine bypass valve 19, the valves provided in the supply line for the atmosphere discharge and boiler auxiliary steam are also fully closed, and the total amount of steam generated in the boiler 1 depends on the load. Under the control of the opening degree of the steam control valve 12, the steam is introduced from the main steam pipe 11 to the high pressure turbine 4.
The reheated steam that has passed through the reheater 2 passes through the fully-opened reheated steam control valve 15 and is entirely guided to the low-pressure turbine 5.

Further, when the load is cut off, such as when the generator 3 is urgently stopped for some reason, the steam generated in the boiler 1 becomes excess steam and passes through the high pressure turbine bypass valve 16 to the reheater 2. It is sent to the condenser 6 through the low pressure turbine bypass valve 19. The steam control valve 12 and the reheat steam control valve are in the opening control state. The conventional example of FIG. 10 shows a valve open / closed state at the time of load shedding. In each valve in the figure, black is fully closed, white is fully open, and black / white mixed is opening control. Is shown.

[0010]

By the way, in the above-described conventional steam turbine plant, when the high-low pressure turbine bypass operation is performed, the opening control of the reheat steam control valve 15 is linked to the steam control valve 12. It was implemented based on one sequence (operation mode) by the mechanical cam. Therefore, the opening degree control of the reheat steam control valve 15 is set to the valve opening degree according to the bypass operation at the time of startup, and the condition that the valve opening degree is fully opened is when the first low pressure load is reached. . Here, generally, the first low load region is approximately 15
%, The second low load region is approximately 20%, so the valve opening degree of the reheat control valve 15 at the time of load shedding becomes small.

Therefore, in order to allow the excess steam at the time of load shedding to be safely and smoothly discharged to the condenser 6, the low pressure turbine bypass valve 19, the high pressure turbine bypass valve 16 and these valves are set in accordance with the excess steam flow rate. It was necessary to set the capacity (size) of the pipe to be set large.
Further, even when the steam turbine is stopped, it is necessary to carry out bypass operation in the reverse order to the above-mentioned start-up, and therefore each main pipe (main steam pipe 11, reheat steam pipe 14, etc.)
In order to keep the pressure of 1 above the minimum pressure, steam was generated more than necessary in the boiler 1. Therefore, it is necessary to discharge (radiate heat) the high-temperature steam to the condenser 6 through the high-pressure steam bypass pipe 17 and the low-pressure steam bypass pipe 20, which causes a problem of wasteful fuel consumption in the boiler 1.

The present invention has been made in view of the above circumstances, and enables a high- and low-pressure turbine bypass valve and a bypass pipe to have a small capacity (small diameter) in a steam turbine plant for performing a high- and low-pressure turbine bypass operation, and The purpose is to reduce boiler fuel consumption when the turbine is stopped.

[0013]

The present invention adopts the following means in order to solve the above problems. The steam turbine plant according to claim 1 is a steam generating boiler equipped with a reheater, a plurality of stages of steam turbines that introduce steam of different pressures to drive a generator, and cools the steam. A reheat steam control valve for controlling the amount of steam to be supplied from the reheater to the low pressure turbine in a steam turbine plant that is configured to perform bypass operation of high and low pressure turbines at the time of startup, and a condenser for condensing water. The opening degree control is provided with a first operation mode used at startup and a second operation mode that is selectively switched after the first operation mode is fully opened.

According to such a steam turbine plant, since the first operation mode used at the time of start-up and the second operation mode which is selectively switched after the first operation mode is fully opened are provided, when the load is cut off. It is possible to give the reheat steam valve a large valve opening degree based on the second operation mode which is not restricted at the time of startup. Also, bypass operation when the turbine is stopped is unnecessary.

In the steam turbine plant according to claim 1, since the reheat steam control valve is provided with a large opening when the load is cut off, the first operation mode is set to a valve opening larger than that of the second operation mode. Set. Further, in the above-described steam turbine plant, in order to reduce the amount of main steam and the amount of reheated steam at the time of load shedding, to the main steam supply line that supplies steam from the boiler to the high-pressure turbine, a load shedding signal for the generator is provided. It is advisable to provide an emergency release valve that opens in response to this.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a steam turbine plant according to the present invention will be described below with reference to the drawings. Figure 1
In the figure, reference numeral 1 is a boiler, 2 is a reheater, 3 is a generator, 4 is a high pressure turbine, 5 is a low pressure turbine, 6 is a condenser, 7 is a control unit, 8 is a condensate pump, and 9 is Spray water line, 10 is a spray water control valve, and 23 is an emergency opening valve.

The steam generated by heating by the heat generated by burning the fuel in the boiler 1 is guided to the high pressure turbine 4 through the main steam pipe 11. A steam control valve 12 is provided in the main steam pipe 11.
And the emergency opening valve 23 is provided, and by performing the opening degree control of the steam control valve 12 according to a power generation (turbine) load,
The amount of steam supplied to the high-pressure turbine 4 is adjusted. The valve opening degree of the steam control valve 12 is changed by changing the steam control valve control hydraulic pressure (hereinafter referred to as control hydraulic pressure) supplied to a servo motor (not shown) according to the power generation load and adjusting the valve lift. The valve opening of the steam control valve 12 increases substantially in proportion to the steam control valve control hydraulic pressure on the horizontal axis, as indicated by the alternate long and short dash line in FIG.

Further, the emergency opening valve 23 is a normally closed valve, which is fully opened instantaneously upon receiving an opening signal from the control unit 7 and promptly discharges the steam generated in the boiler 1 to the outside from the main steam pipe 11. It has a function. In addition, in general, the control unit 7
A solenoid valve (not shown) is opened by a signal output from the valve, and working fluid (such as air) is supplied to a cylinder for actually opening and closing the valve body of the emergency opening valve 23.

The steam that has driven the turbine by passing through the high-pressure turbine 4 is guided to the reheater 2 provided integrally with the boiler 1 through the low temperature reheat steam pipe 13. Reheater 2
The passing steam is reheated by receiving heat generated by burning the fuel in the boiler 1, and is guided to the low pressure turbine 5 through the reheat steam pipe 14. The reheat steam pipe 14 is provided with the reheat steam control valve 15 that controls the opening degree in conjunction with the opening degree control of the steam control valve 12 described above. The reheated steam amount is supplied to the low-pressure turbine 5.

The opening degree of the reheat steam control valve 15 is controlled by referring to FIG.
As indicated by the solid line in (First Embodiment), a first operation mode used when starting the steam turbine plant and a second operation mode used during normal operation are provided. Note that the load cutoff and normal stop of the steam turbine, which will be described later, are also performed from the state during normal operation. In the first operation mode, the sequence is controlled by the mechanical cam, and when compared with the second operation mode, the valve opening degree is controlled in the region where the large control hydraulic pressure acts (on the right side in FIG. 8). Then, after the valve opening reaches 100% full opening in the first operation mode, the sequence is switched by the electric cam, and the second operation mode is automatically selected.

That is, in the first operation mode, the valve opening 10
When it reaches 0% (fully opened), the sequence is switched by the electric cam and the mode automatically shifts to the second operation mode, and the control oil pressure is restarted until it falls to a value corresponding to 100% of the valve opening in the second operation mode. The fully opened state of the hot steam control valve 15 is maintained. As a result, the reheat steam control valve 15 during normal operation
The valve opening of is larger than that for the same power generation load as compared with the operation mode at the time of startup. The reheated steam thus controlled by the opening degree of the reheated steam control valve 15 and supplied to the low-pressure turbine 5 performs the work of driving the low-pressure turbine 5, and then is sent to the condenser 6 to be condensed.

The main steam pipe 11 and the low temperature reheat steam pipe 13 are connected by a high pressure steam bypass pipe 17 having a high pressure turbine bypass valve 16. The high-pressure steam bypass pipe 17 allows an excess amount of steam to flow directly to the low-temperature reheat steam pipe 13 in accordance with the operating condition of the high-pressure turbine 4, and the high-pressure steam bypass pipe 17 keeps the detected value of the pressure sensor 18 at a predetermined pressure. The opening degree of the turbine bypass valve 16 is controlled. A low pressure steam bypass pipe 20 having a low pressure turbine bypass valve 19 is connected between the reheat steam pipe 14 and the condenser 6. This low-pressure steam bypass pipe 20 is used for the low-pressure turbine 5
The surplus steam amount is caused to flow directly to the condenser 6 in accordance with the operating conditions of the above, and the opening degree control of the low pressure turbine bypass valve 19 is performed so as to maintain the detected value of the pressure sensor 21 at a predetermined pressure.

The operation of the steam turbine plant having the above structure will be described below. In each valve in the figure, black is fully closed, white is fully open, and black / white mixed is for opening control. At the time of starting the steam turbine plant, an operation operation called high and low pressure turbine bypass operation is performed from before steam aeration until 100% load is reached. At the first stage (before steam aeration) in this high and low pressure turbine bypass operation, as shown by the thick line in FIG. 1, the entire amount of steam generated in the boiler 1 (excluding atmospheric discharge, boiler auxiliary steam, etc.) Through the high pressure steam bypass pipe 17 to the reheater 2. That is, the entire amount of the steam generated in the boiler 1 flows by bypassing the high pressure turbine 4 in which the steam control valve 12 is fully closed.

The steam thus sent to the reheater 2 is reheated by the heating of the boiler 1, and this reheated steam is introduced from the reheat steam pipe 14 through the low pressure steam bypass pipe 20 to the condenser 6. That is, the reheated steam reheated in the reheater 2 has a total amount of the low pressure turbine 5 with the reheated steam control valve 15 fully closed.
Will be bypassed and flow to the condenser 6. This first
At the stage, the high-pressure turbine 4 and the low-pressure turbine 5 are in a stopped state because the steam generated in the boiler 1 does not have sufficient capacity (steam amount, temperature and pressure) to operate the steam turbine.

At the second stage of high / low pressure turbine bypass operation (steam ventilation-steam co-entry), as shown by the thick line in FIG. 2, the steam generated in the boiler 1 is steam control valve 12 and high pressure turbine bypass valve. A part of the high-pressure turbine 4 is ventilated by controlling the opening degree of 16 to raise the temperature of the steam turbine. At this time, the valve opening degree of the steam control valve 12 rises in response to the control hydraulic pressure set as shown by the one-dot chain line in FIG. The high-pressure turbine 4 and the high-pressure steam bypass pipe 17
After passing through, the steam is merged and then sent to the reheater 2 to be heated by the boiler 1. Further, the reheated steam that has passed through the reheater 2 and has been reheated is partially ventilated to the low pressure turbine 5 by controlling the opening degree of the reheat steam control valve 15 and the low pressure turbine bypass valve 19, and the temperature of the steam turbine is reduced. Raise. At this time,
The valve opening degree of the reheat steam control valve 15 is increased by receiving the control oil pressure in the sections a and b during the startup (first operation mode) set as shown by the solid line in FIG.

At the third stage of high / low pressure turbine bypass operation (combination of steam to reach first low load), the high pressure turbine bypass valve 16 is fully closed as shown by the thick line in FIG. Therefore, the entire amount of steam generated in the boiler 1 (excluding atmospheric emission, boiler auxiliary steam, etc.) is controlled by the opening degree of the steam control valve 12 according to the load of the generator 3, and the main steam pipe 11 serves as a drive source. It is guided to the high-pressure turbine 4. Further, the reheated steam that has passed through the reheater 2 and is reheated is partially ventilated to the low pressure turbine 5 by controlling the opening degree of the reheat steam control valve 15 and the low pressure turbine bypass valve 19 to drive the steam turbine. Used as a source. At this time, the valve opening degree of the reheat steam control valve 15 is increased by receiving the control hydraulic pressure in the sections b to c during the startup (first operation mode) set as shown by the solid line in FIG. . The opening degree of the reheat steam control valve 15 is interlocked with the steam control valve 12 whose opening degree is controlled according to the load of the generator 3.

At the fourth stage of the high-low pressure turbine bypass operation (first low load arrival to second low load arrival), as shown in FIG. 4, the high pressure turbine bypass valve 16 is fully closed as in the third stage described above. Therefore, the total amount of steam generated in the boiler 1 (excluding atmospheric emission, boiler auxiliary steam, etc.) is the steam control valve 1
The high pressure turbine 4 from the main steam pipe 11 under the control of the opening degree of 2
Be led to. The reheated steam that has passed through the reheater 2 has the reheated steam control valve 15 fully opened and the low-pressure turbine bypass valve 19 fully closed. The entire amount excluding the reheated steam introduced to 6 is introduced to the low pressure turbine 5. At this time, the valve opening degree of the reheat steam control valve 15 receives the control oil pressure in the sections c to d to e during the startup (first operation mode) set as shown by the solid line in FIG. open.

In this way, when the opening control of the reheat steam control valve 15 reaches the full opening (100%) at startup, the subsequent opening control is performed during the normal operation (second operation) shown in FIG. Mode) automatically. That is, the reheat steam control valve 1
The valve opening of No. 5 is from a to b to c to d to e at the time of startup (first operation mode) set as shown by the solid line in FIG. 8 to that at normal operation (second operation mode). Go to g-f-e. Since the valve opening degree of the reheat steam valve 15 during normal operation is set to be larger than that at the startup control for the same control oil pressure, in other words, for the same load of the generator 3, the load is reduced. The fully open state can be maintained as long as the driving situation does not change.

In this way, at the final stage 5 of high and low pressure turbine bypass operation (second low load reaches to 100% load), in addition to the high pressure turbine bypass valve 16 and the low pressure turbine bypass valve 19, atmospheric release and boiler are performed. The valves provided in the supply line for auxiliary steam, etc. are also fully closed, and the total amount of steam generated in the boiler 1 is controlled by the opening control of the steam control valve 12 according to the load (during normal operation) Tube 11
From the high pressure turbine 4. The reheated steam that has passed through the reheater 2 is fully opened by the opening degree control of the reheated steam control valve 15 between the sections g to f to e, and the entire amount is guided to the low pressure turbine 5.

Next, when the load is cut off, for example, when the generator 3 is stopped urgently for some reason, it will be described with reference to FIG. This load shedding is performed, for example, when the control unit 7 receives a signal output from the circuit breaker (not shown) of the generator 3. At this time, the control unit 7 controls the emergency opening valve 23
To open. The steam generated in the boiler 1 becomes surplus steam, the main flow is discharged to the outside of the system from the emergency opening valve 23, and the rest is sent to the reheater 2 through the steam control valve 12 and the high pressure turbine 4. Then, the reheated steam reheated in the reheater 2 is
Further, it is discharged to the condenser 6 through the reheat steam control valve 15 and the low pressure turbine 5.

As described above, since the main flow of surplus steam at the time of load shedding is discharged from the emergency opening valve 23, the amount of steam flowing from the main steam pipe 11 to the high pressure turbine 4 becomes small.
Therefore, in consideration of using it also as the main steam flow path at the time of load shedding, conventionally, the capacity (size) of the high-pressure turbine bypass valve 16 and the high-pressure steam bypass pipe 17 was set large, but it can be reduced. it can. That is, since the capacities of the high-pressure turbine bypass valve 16 and the high-pressure steam bypass pipe 17 required for the above-described high / low-pressure turbine bypass operation may be secured, a large capacity such as when the load is cut off for flowing a large amount of excess steam becomes unnecessary. .

Also, the amount of steam reheated when the load is cut off is reduced by the amount of steam released from the emergency release valve 23. Furthermore, the valve opening degree of the reheat steam control valve 15 is larger during normal operation than during startup. Therefore, it is not necessary to determine the capacities of the low-pressure turbine bypass valve 19 and the low-pressure steam bypass pipe 20 in consideration of the amount of reheated steam when the load is cut off. Therefore, the capacities are reduced in accordance with the high-low pressure turbine bypass operation. be able to.

Next, the time when the steam turbine is stopped will be described with reference to FIGS. 7 and 8. When such a steam turbine is stopped, unlike the conventional case, the high pressure turbine bypass valve 16 and the low pressure turbine bypass valve 19 are closed, and
The valve opening degree of the reheat steam control valve 15 is controlled in the normal operation mode. Therefore, even if the load of the generator 3 is reduced, a valve opening larger than that of the conventional one can be obtained. Therefore, in order to keep the pressure of the main steam pipe 11 and the reheat steam pipe 14 at the minimum pressure, the boiler 1
It is possible to suppress the generation of steam more than necessary. That is, since a large valve opening can be set for the reheat steam control valve 15, the minimum flow rate of the reheat steam can be secured, and therefore, the high temperature steam is recovered through the high pressure steam bypass pipe 17 and the low pressure steam bypass pipe 20. Since it is not necessary to exhaust (radiate heat) to the water tank 6, the fuel consumption amount in the boiler 1 can be reduced.

By the way, in the above-mentioned embodiment, the case where the reheat steam control valve 15 is one is explained, but the reheat valve 1
In order to improve the responsiveness of No. 5, two reheat steam control valves 1
You may arrange | position 5 in parallel and employ | adopt a structure. FIG. 9 shows an example of the operation mode in the case where the two reheat steam control valves 15 are arranged in parallel (second embodiment), and a region where the valve opening degree is small (specifically, the section a-). In c and g to h), the two reheat steam control valves 15 are set such that the valve opening degree with respect to the control oil pressure is slightly shifted both at the time of startup and at the time of normal operation.

Even if such control of the valve opening degree is carried out, the high pressure turbine bypass valve 1 will be operated as in the above-mentioned embodiment.
6. The capacity (size) of the high pressure steam bypass pipe 17, the low pressure turbine bypass valve 19 and the low pressure steam bypass pipe 20 can be reduced. Further, since a large valve opening can be set for the reheat steam control valve 15, it is not necessary to exhaust the high temperature steam to the condenser 6 through the high pressure steam bypass pipe 17 and the low pressure steam bypass pipe 20 (heat dissipation). The fuel consumption in the boiler 1 can be reduced.

The configuration of the present invention is not limited to the above-described embodiment, and may be appropriately changed within the scope of the gist of the present invention. For example, for a steam turbine, two stages of high pressure and low pressure are used. It is also possible to apply to a multi-stage steam turbine having three or more stages, and it is also possible to control the sequence during normal operation with a mechanical cam and switch the sequence with an electric cam during startup.

[0037]

According to the steam turbine plant of the present invention, the opening degree of the reheat steam control valve for controlling the amount of steam supplied from the reheater to the low pressure turbine is controlled by the first operation at the time of starting.
And the second operation mode which is selectively switched after being fully opened in the first operation mode and used during normal operation, the high pressure turbine bypass valve, the high pressure steam bypass pipe, the low pressure turbine bypass valve, and the low pressure steam are provided. It is not necessary to consider the steam flow rate at the time of load shedding for the bypass pipe, and as a result, it is possible to reduce the capacity.

Further, since the valve opening control during normal operation is different from that during startup, a large valve opening can be set for the reheat steam control valve. Therefore, when the steam turbine is stopped, it is not necessary to exhaust the high-temperature steam (heat radiation) to the condenser through the high-pressure steam bypass pipe and the low-pressure steam bypass pipe, and as a result, it is possible to reduce the fuel consumption in the boiler. Play.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first stage (before steam aeration) in a valve opening / closing state showing an embodiment of a steam turbine plant according to the present invention.

FIG. 2 is a system diagram of a second stage (steam aeration-steam coexistence) in a valve open / close state showing an embodiment of a steam turbine plant according to the present invention.

FIG. 3 is a system diagram showing a valve opening / closing state in a third stage (combining steam to reach a first low load) showing an embodiment of a steam turbine plant according to the present invention.

FIG. 4 is a system diagram showing a valve opening / closing state in a fourth stage (first low load arrival to second low load arrival) showing an embodiment of a steam turbine plant according to the present invention.

FIG. 5 shows an embodiment of a steam turbine plant according to the present invention in a valve open / closed state in a fifth stage (second low load arrival to 1).
It is a system diagram of (load reaching 00%).

FIG. 6 is a system diagram showing an embodiment of a steam turbine plant according to the present invention when a valve is opened and closed and a load is cut off.

FIG. 7 is a system diagram when a valve is opened / closed and the turbine is stopped, showing an embodiment of a steam turbine plant according to the present invention.

FIG. 8 is a graph showing a first embodiment relating to valve opening control of a steam control valve and a reheat steam control valve in the present invention.

FIG. 9 is a graph showing a second embodiment relating to valve opening control of a steam control valve and a reheat steam control valve in the present invention.

FIG. 10 is a system diagram showing a conventional steam turbine plant in a valve open / closed state when a load is cut off.

[Explanation of symbols]

1 boiler 2 reheater 3 generator 4 high pressure turbine 5 Low pressure turbine 6 condenser 11 Main steam pipe 12 Steam control valve 13 Low temperature reheat steam pipe 14 Reheated steam pipe 15 Reheat steam control valve 16 High pressure turbine bypass valve 17 High pressure steam bypass pipe 19 Low pressure turbine bypass valve 20 Low pressure steam bypass pipe 23 Emergency release valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01D 19/00 F01D 19/00 N 21/00 21/00 DR V F01K 7/24 F01K 7/24 B 13/02 13/02 ABC H02P 9/04 H02P 9/04 E 9/08 9/08 AF term (reference) 3G071 AB01 BA05 CA01 CA03 DA06 FA01 GA06 HA02 JA03 5H590 AA02 CA02 EA01 EA05

Claims (3)

[Claims] 1. A steam generating boiler equipped with a reheater, a plurality of stages of steam turbines for driving a generator by introducing steams of different pressures, and a condenser for cooling the steam to condense it. In a steam turbine plant configured to perform high and low pressure turbine bypass operation at startup, in controlling the opening degree of a reheat steam control valve for controlling the amount of steam supplied from the reheater to the low pressure turbine, First used at startup
And a second operation mode which is selectively switched after the first operation mode is fully opened in the steam turbine plant. 2. The steam turbine plant according to claim 1, wherein the first operation mode is set to a valve opening larger than that of the second operation mode. 3. A main steam supply line for supplying steam from the boiler to the high-pressure turbine is provided with an emergency opening valve which is opened upon receiving a load cutoff signal of the generator. Steam turbine plant.