JPS63113104A - Control device for steam turbine - Google Patents

Abstract

PURPOSE:To keep the permanent speed change constant for the rated load operation, in which the load for the day time differs from that for the night time, by constituting a fulcrum of a lever connected to a governor's rotating pilot valve as a moving fulcrum. CONSTITUTION:A synchronizer 11 and a governor's rotating pilot valve are connected by means of a plurality of levers 21a-21c. A fulcrum 27 of the pilot- valve (13)-side lever 21c of these levers is made movable, and a fulcrum moving device 25 is prepared. During a rated load operation in the day time, the turbine is operated with the lever (21c)'s fulcrum placed at the position of the moving fulcrum 27a, while, during a rated load operation in the night time the turbine is operated with the lever's fulcrum placed at the position of the moving fulcrum 27b. With this contrivance, the permanent speed change can be kept constant for both day and night time, thereby preventing a trip of the turbine caused by an overspeed.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention maintains the exhaust steam amount of the turbine constant regardless of fluctuations in the load of the steam turbine, and then adjusts the settling speed adjustment rate of the turbine. The present invention relates to a control device for a steam turbine that is capable of always maintaining a constant value.

(Prior Art) Steam turbine plants are generally known that supply electric power to a small area and utilize the exhaust steam for purposes such as water distribution plants.

Figure 4 shows the configuration of this type of steam turbine plant, in which the main steam 3 generated in the boiler 2 is transferred to the main steam stop valve 4.
, is guided to the steam turbine 1 via the steam control valve 5, performs work in the steam turbine 1 and drives the generator 6, and is then discharged outside the steam turbine 1 as exhaust steam 7. The exhaust steam 7 is intended to be used in a water supply plant (not shown).

Incidentally, power demand in a small area generally tends to be high during the day and low at night, and the load on the turbine varies accordingly.

A conventional steam turbine plant is known in which load control is performed by changing the flow rate of main steam 3 by controlling the opening and closing of a steam control valve 5.

However, in a water supply plant, it is desirable to maintain the amount of exhaust steam 7 constant in order to keep the amount of fresh water constant, so the flow rate of the main steam 3 is changed according to the load as described above. However, there is a problem in that the amount of exhaust steam 7 of the turbine is not constant.

That is, in a steam turbine plant equipped with a water supply plant, it is not possible to perform load control by changing the flow rate of the main steam 3.

On the other hand, a system is known in which load control is performed by changing the pressure of the main steam 3 according to the load on the turbine.

This type of power is used during daytime when there is a high demand for electricity (during high load).
The main steam 3, which has been brought to the normal rated pressure on the boiler side, flows into the steam turbine 1 through the steam control valve 5, and when there is little electricity demand at night (low load), the boiler Low-pressure main steam 3 whose pressure has been lowered on the side is made to flow into the steam turbine 1 through the steam control valve 5.

Here, high load and low load times will be explained using the flow rate characteristics of the steam control valve shown in FIG.

FIG. 5 shows the flow rate characteristics when four steam control valves are provided, and are denoted by symbols A and B.

C and D indicate the opening positions of the first to fourth steam control valves, and symbol E indicates the fully open position of each steam control valve.

The operating position 9a under high load is controlled by the second valve, and the third and fourth valves remain fully closed. The operating position 9b at low load is controlled by the fourth valve, and the steam control valve is almost fully open. The flow rate characteristics are determined so that the steam flow rate at each operating position is kept substantially constant, and in this case, the rated steam flow rate is a flow rate indicated by the symbol F. By controlling in this way, the amount of exhaust steam is always maintained.

Next, a conventional control device for controlling the opening degree of the steam control valve 1- will be explained with reference to FIG.

Control from the start of the steam turbine to around the rated rotational speed is performed by the operation of the starting device 14. The starter 14 is controlled by a starter drive motor 15, and when this is controlled, control oil 24 is supplied to the lower part of the piston 17a of the speed relay 17 via the auxiliary pilot valve 16 and the governor rotation pilot valve 13.

As a result, the speed relay 17 pushes up the upper lever 21h and pushes down the steam control valve oil cylinder pilot valve 18 via the lever 21i1-Rukshaf) 22b and lever 21j. Then, the control oil 24 is supplied to the lower part of the piston 19a of the steam control valve oil cylinder 19. Steam control valve oil cylinder 19
When is driven, the steam control valve 5 opens via the torque shaft 22c. The auxiliary pilot valve 16 and the steam control valve oil cylinder pilot valve 18 have a feedback lever 21e,
21h is provided, and the steam control valve 5 is opened only by a control signal from the starter drive motor 15.

When the rotational speed of the turbine increases to around the rated rotational speed in this manner, the governor rotating pilot valve 13 moves down and blocks the pilot valve boat, so that control oil no longer flows.

Starting device 14 controls from around the rated rotation speed to the rated load.
This is done by the operation of the synchronizer 11 after the engine is fully opened. The synchronizer 11 is controlled by a synchronizer drive motor 12, and when this is controlled, the sleeve of the governor rotation pilot valve 13 is pushed down, and the control oil 24 is again transferred to the speed relay 17.
The steam control valve oil cylinder 19 and the steam control valve 5 are automatically opened in the same manner as described above.

In addition, 21a- in FIG. 5 indicates a lever, and 22a-
-c indicates a torque shaft.

The steam turbine control system described above has a fixed speed arbitration rate of 3 to 5%, as is generally well known, and this is due to the constant speed adjustment rate between the governor rotation pilot valve 13 and the steam control valve 5. Determined by lever ratio.

Here, the relationship between the daytime and nighttime settling speed adjustment rates will be explained with reference to FIG. If a load shedding occurs during operation at the daytime rated load operating position 9a, the opening degree of the steam control valve changes to the daytime no-load operating position 10a. At this time,
The amount of change in the opening degree of the steam control valve is Za. In this case, the settling speed adjustment rate is adjusted to 5% so that the turbine settling rotation speed is about 105%.

On the other hand, if a load cutoff occurs during operation in a state shifted to the nighttime rated load operating position @9b, the opening degree of the steam control valve changes to the nighttime no-load operating position 10b. At this time,
The amount of change in the opening degree of the steam control valve is zb. In other words, between daytime and nighttime, the amount of change in the steam control valve opening during load shedding is Za
There is a large change of approximately three times from zb to zb. Since the settling speed adjustment rate is adjusted to 5% when the change mZa is, the settling speed adjustment rate when the change amount zb of the steam control valve opening at night is about three times as high as 15%.

(Problem to be solved by the invention) When load shedding occurs during operation at rated load at night,
The settling rotation speed of the turbine becomes approximately 115%, and the overspeed of the turbine greatly exceeds the set rotation speed of 110% of the emergency governor (not shown), causing the emergency governor to operate and tripping the turbine.

When the settling speed adjustment rate is adjusted to 5% in daytime operating conditions, in the conventional system, the lever ratio between the governor co-rotating pilot valve 13 and the steam control valve 5 is constant, so the night operating condition In this case, the settling speed adjustment rate is approximately tripled to 15%, and if a load shedding occurs during rated load operation at night, the turbine will not only greatly overspeed, endangering the turbine, but also damage the emergency governor (not shown). ), which caused the turbine to trip.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to be able to always maintain a constant amount of exhaust steam even if the turbine load fluctuates, and to be able to maintain a constant rated load during the day and at night. An object of the present invention is to provide a control device for a steam turbine that can always keep a constant speed regulation rate constant during operation.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the first invention provides a synchronizer, a governor rotary pilot valve whose sleeve expands and contracts in accordance with the operation of the synchronizer, and a governor rotary pilot valve, which A control device for a steam turbine comprising: a lever system having a plurality of fulcrums that converts the expansion/contraction operation of a governor rotating pilot valve into an opening/closing operation of a steam control valve in response to an expansion/contraction operation of a governor rotation pilot valve, the plurality of fulcrums of the lever system; Among these, the fulcrum on the side of the governor rotation pilot valve is configured as a moving fulcrum, and the second
In the invention, an intermediate fulcrum of the lever connecting the synchronizer and the governor pilot valve is configured with a speed reset device, and the speed reset device is actuated by a load cutoff signal during high load operation of the turbine. It is characterized by the following.

(Function) According to the first invention, the movable fulcrum 27 and the fulcrum moving device 2
5 is provided, and when shifting from daytime to nighttime driving, the moving fulcrum 27 of the lever 21c is moved by the operation of the fulcrum moving device 25. Lever 21 for daytime and night driving
The lever ratio is changed by moving the fulcrum of c. This lever ratio to be changed corresponds to the amount of change Za in the opening degree of the steam regulator valve between rated load and no load during the daytime, and the amount zb of change in the opening degree of the steam regulator valve between rated load and no load at night. Since they are set correspondingly, the settling speed adjustment rates for daytime and nighttime can always be maintained constant.

Further, according to the second invention, a speed reset device 42 is provided, and this speed reset device 42 always serves as a fixed fulcrum for the lever 21a during low load, etc., and serves as a fixed fulcrum for the lever 21a during high load operation. ? It is activated only when the signal is issued. When the speed reset device 42 is activated, the sleeve of the governor rotation pilot valve 13 is pushed and the valve opening of the steam control valve 5 is suddenly closed. Therefore, the steam control valve 5
The opening degree of the valve a changes from a temporarily abruptly closed state to a closed state due to load cutoff, and the change mZc in the opening degree of the steam control valve can be reduced.

(Embodiment) Hereinafter, an embodiment of the steam turbine control device according to the first invention will be described with reference to FIGS. 1 and 2. In addition,
Components that are the same as those in FIG. 6 are designated by the same reference numerals, and descriptions of the components that overlap with those described in the above-mentioned conventional technique will be omitted.

The lever system for controlling the opening degree of the steam control valve 5 has almost the same structure as the conventional lever system.

The lever 21c is provided with a movable fulcrum 27 instead of the conventional fixed fulcrum 23b (FIG. 6), and this movable fulcrum 27 is connected to the fulcrum movable bag fi ¥25.

When this device 25 operates, the moving fulcrum 27 moves from a position 27a shown by a solid line to a position 27b shown by a dotted line. Further, a guide 26 is provided to prevent the lever 21c from moving left or right.

During the daytime rated load operation, the fulcrum of the lever 21c is operated at the movable fulcrum 27a, and in the flow rate characteristics of the steam control valve shown in FIG. 5, it is operated at the daytime rated load operation position 9a. When load interruption occurs at this time, the flow rate characteristics change to the daytime no-load operating position 10a, and the amount of change in the steam control valve opening becomes Za. Here, the settling adjustment rate is determined to be 5% so that the settling rotation speed of the turbine is approximately 105%.

On the other hand, during rated load operation at night when the electric power i5f: is low, the fulcrum of the lever 21c is the fulcrum moving bag N25. It is moved to the position of the moving fulcrum 27b by the operation of . In the flow rate characteristics of the steam control valve shown in FIG. 5, it is operated at the operating position 9b during the rated load at night. If a load shedding occurs at this time, the flow m characteristics indicate that the operating position 10b at no-load time is at night.
The amount of change in the opening degree of the steam control valve is zb.

In this way, the amount of change in the steam control valve opening between daytime and nighttime is Z
Since there is a large change from a to zb, the fulcrum of the lever 21c is correspondingly moved from the moving fulcrum 27a to the 27b position, thereby changing the lever ratio. By changing the lever ratio, even if the amount of change in the opening degree of the steam control valve during night load shedding is zb,
The settling speed of the turbine after load shedding is approximately 1, same as during the day.
05%, and the settling speed adjustment rate remains constant at 5%. The turbine is then operated safely without overspeeding or tripping.

Next, the fulcrum moving device 25 will be explained.

As shown in FIG. 2, the fulcrum moving device 25 includes a cylinder 29,
Piston 30, piston rod 31, stopper 41,
and a spring 40, and control oil 24 is supplied from the left side of the piston 30 in the figure. or,
A spring 40 attached to the right side of the piston 30 in the figure always urges the piston 30 and the piston rod 31 to the left in the figure. A pin 28 is attached to the tip of the moving fulcrum 27a, and the pin 28 is configured to move within a long groove 34 formed in the lever 21c. Further, the base end of the movable fulcrum 27a is connected to the piston rod 31 of the fulcrum moving device 25.
It is connected to the tip of the body via a nut 32.

During daytime rated load operation, the three-way solenoid valve 35 is in an excited state, and the control oil 24 is supplied to the left side of the piston 30 of the fulcrum moving device 25 via the three-way solenoid valve 35, and the spring 40
The moving fulcrum is moved to the position 27a against the spring force of . At this time, the pin 28 and the long groove 34 of the lever 21c
The stopper 41 is provided on the piston 30 to ensure a gap W between the piston 30 and the piston 30. Further, since the fulcrum portion of the lever 21c is a long groove 34, a guide 26 is provided, and this guide 26 prevents the lever 21c from moving from side to side. There is a connecting pin 33 on the left side 4 part of the lever 21C in the figure.
is fixed, and this connecting bin 33 is adapted to move along the guide 26.

As a result, the lever 21c does not move in an arc with the bin 28 as a fulcrum, and sometimes the lever 21c moves slightly to the left. This movement can be escaped by the gap W.

During rated load operation at night, the pressure of the main steam 3 is lowered in the boiler 2. A pressure switch 36 is provided in the line of the main steam 3, and the pressure of the main steam is detected by the pressure switch 36.
When the pressure decreases to the set value, the pressure switch 36 is turned on. When the pressure switch 36 is turned on, the three-way solenoid valve 35 becomes de-energized via the relay 37, and the fulcrum moving device 25
The control oil 24 on the left side of the piston 30 in the figure is released to the drain line 39. As a result, the piston 30 and piston rod 31 move to the left in the figure due to the force of the spring 40, and the moving fulcrum moves to the position 27b.

Reference numeral 38 is a power source.

Due to the above series of operations, during daytime rated load operation,
The fulcrum of the lever 21c is operated at the position of the movable fulcrum 27a, and during nighttime rated load operation, the fulcrum of the lever 21c is operated at the position of the movable fulcrum 27b. Further, when the operation is changed from daytime to nighttime or from nighttime to daytime, the pressure change of the main steam 3 is detected by the pressure switch 36, the three-way solenoid valve 35 is switched, and the fulcrum moving device 25 moves the movable fulcrum 27 to 27a.
to 27b, and from 27b to 27a.

Therefore, it is possible to ensure the lever ratio as required during the daytime and nighttime, and it is possible to maintain the settling speed adjustment rate constant.

According to an embodiment of the second invention, a speed reset device 42 is provided in place of the conventional fixed fulcrum 23a (FIG. 6) of the lever 21a, and according to this embodiment, the load can be adjusted during daytime rated load operation. Even if a cutoff occurs, the speed reset device 42 does not operate and functions in the same manner as the fixed fulcrum 23a of the conventional lever 21a.

On the other hand, when load shedding occurs during rated load operation at night, the speed reset device 42 is activated, and the lever 21g is pushed upward by a distance corresponding to the stroke S1 of the speed reset device 42.

As a result, the sleeve of the governor rotation pilot valve 13 is pulled up by a distance S2, the boat of the drain line 39 is opened, and the control oil below the piston 17a of the speed relay 17 is released to the drain line 39. Then, the steam control valve 5 is moved to the operating position 9 during the rated load at night as shown in FIG.
Position 9C when the night speed reset device is activated from b
until suddenly closed. With this operation, even if the load is cut off at the operating position ff19a during the rated load at night, the steam control valve 5 will
The actuation of the speed reset device 42 causes a sudden closing to position 9c, resulting in load shedding at position 9C. As a result, even if the nighttime setting speed adjustment rate is 15%, the amount of change in the opening of the steam control valve is as small as Zc, so the turbine can be operated safely without overspeeding or tripping.

Next, the speed reset device 42 will be explained.

The speed reset device 42 has a swingable lever 46 inside.
This lever 46 and the upper lever 21a are connected via a rod 47. The lever 46 is always urged upward by the spring 43, and the hook 45
6 stopper. This hook 45 is connected to the solenoid 44.

Solenoid 4 responds to the nighttime operating conditions and load shedding signal.
4 is energized and the hook 45 serving as a stopper for the lever 46 is removed, the lever 46 is pushed up by the spring 43 and the upper lever 21a is pushed upward by a distance corresponding to the stroke Sl of the speed reset device 42. It has become.

According to this embodiment, this speed reset device 4
By adjusting the stroke S1 of 2 by 2J, the position 9C when the speed reset device 42 is activated can be arbitrarily determined, and the amount of change Zc in the opening degree of the steam control valve can also be arbitrarily determined.

〔Effect of the invention〕

As is clear from the above description, according to the first invention, a lever fulcrum moving device is provided between the governor rotation pilot valve and the steam control valve to open the steam control valve during load shedding during the day and at night. Since the lever ratio is changed in accordance with the amount of change in temperature, the constant speed adjustment rate can be maintained constant during the day and at night.

On the other hand, according to the second invention, since the speed reset device is provided between the synchronizer and the governor rotation pilot valve, it is possible to instantly close the steam control valve to an arbitrary position when the load is cut off at night. This makes it possible to reduce the amount of change in the opening degree of the steam control valve.

With either invention, when the load is removed from different operating conditions during the day and night, the turbine is operated safely without overspeeding or tripping.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of a steam turbine control device according to the first invention, Fig. 2 is an explanatory diagram showing an enlarged view of the fulcrum moving device in Fig. 1, and Fig. 3 is a system diagram showing an embodiment of the steam turbine control device according to the first invention. Fig. 4 is a system diagram showing the flow of steam in a conventional steam turbine, and Fig. 5 is an explanatory diagram showing the flow rate characteristics of the steam control valve during the day and at night. , 6th
The figure is a system diagram of a conventional steam turbine control device. DESCRIPTION OF SYMBOLS 1...Steam turbine, 2...Boiler, 5...Steam control valve, 11...Synchronizer, 12...Synchronizer drive motor, 13...Governor four-turn pilot valve, 14・
... Starting device, 15... Starting device driving motor, 17
...Speed relay, 21a-...Lever, 22a-
c=・) Lux shaft, 23a=c...fulcrum, 25・
...Fully point moving device, 27... Moving fulcrum, 35... Three-way solenoid valve, 36... Pressure switch, 42... Speed reset device fZ. Applicant's agent Sato - Yuman 4 diagrams Yan Qi Rujo Masu Kaido Shine r+""j

Claims (1)

[Scope of Claims] 1. A synchronizer, a governor rotating pilot valve whose sleeve expands and contracts in response to the operation of the synchronizer, and a steam governor rotating pilot valve whose sleeve expands and contracts in response to the expansion and contraction of the governor rotating pilot valve. In a steam turbine control device comprising a lever system having a plurality of fulcrums that converts the opening/closing operation of a control valve, a fulcrum on the governor rotation pilot valve side among the plurality of fulcrums of the lever system is moved as a fulcrum. A steam turbine control device comprising: 2. A synchronizer, a governor rotary pilot valve connected to the synchronizer via a lever so that the sleeve expands and contracts in response to the operation of the synchronizer, and a governor rotary pilot valve that expands and contracts in response to the expansion and contraction of the governor rotary pilot valve. A control device for a steam turbine comprising a lever system having a plurality of fulcrums that converts this operation into an opening/closing operation of a steam control valve in accordance with the above, wherein the lever system connects the synchronizer and the governor pilot valve. A control device for a steam turbine, characterized in that the intermediate fulcrum is configured with a speed reset device, and the speed reset device is activated by a load cutoff signal during high-load operation of the turbine.