JPS59226210A - Controlling device of cross compound turbine - Google Patents

Abstract

PURPOSE:To surely prevent the hunting and overrunning of a cross compound turbine from occurring by a method wherein a reheat steam control valve is forcibly closed when the rotational frequency of either one of the two shafts of the cross compound turbine measured by the rotational frequency detectors provided on the shafts respectively exceeds the preset value. CONSTITUTION:Rotational frequency detectors 10 and 11, the output signals of which are inputted to the speed function means 18, 23 and 31, are provided on the primary and secondary turbine shafts of a cross compound reheat turbine. The respective speed function means 18, 23 and 31 are provided for issuing ''valve open'' and ''valve close'' signals based upon the turbine speed and close a reheat steam control valve when the rotational frequency of either one of the shafts exceeds the preset value. Concretely, the output of the speed function means 18 is sent to a valve opening setting means 20. The outputs of the speed function means 23 and 31 are sent through a lower value priority circuit 25 to a valve opening setting means 27. Finally, the driving parts 22 and 29 of a steam regulating valve 5 and of an intercept valve 7, both of which are arranged on a primary turbine side, are controlled in accordance with the outputs of the valve opening setting means 20 and 27, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a cross compound reheat turbine having two shafts.

[Background of the invention]

Control devices for cross-compound reheat turbines that have been commonly used in the past are broadly classified into electric types and mechanical/hydraulic types depending on the working medium. In addition, looking at the configuration of the control system, there are two methods: (a) detecting the rotation speed of each of the two shafts and controlling with the lower signal, and (b) detecting the rotation speed of the primary turbine shaft and controlling the main steam. In addition to opening and closing the valve, 2
There is a method in which the reheat steam control valve is opened and closed by detecting the rotation speed of the secondary turbine.

The control method using a low value signal in (a) above can be configured as an electric control device, but cannot be applied to a mechanical or hydraulic control device. The reason is that it is difficult to compare two rotational speed signals in mechanical/hydraulic systems.

In addition, the method of controlling the two axes individually in (b) is an electric type 9
Both mechanical and hydraulic types can be applied, but they have the disadvantage of being prone to hunting.

As mentioned above, in mechanical/hydraulic systems, in order to prevent hunting that tends to occur when the rotation speed of each of the two shafts is detected and controlled individually, the rotation speed detector installed on the primary turbine shaft is used to detect the rotation speed of the primary, When controlling both secondary turbine shafts,
There is a risk that the secondary turbine shaft will overrun when the load on the secondary turbine shaft decreases.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a mechanical/hydraulic type cross compound turbine control device that is free from the risk of hunting or overrun.

[Summary of the invention]

In order to achieve the above object, the control device of the present invention is provided with a rotation speed detector on one shaft of the cross compound reheat turbine, and based on the detection result of the above detector, the main steam control valve and the reheat steam The main body is a mechanical/hydraulic control device that opens and closes the control valve, and a rotation speed detector is provided on the other axis of the above shaft separately from the above, and the rotation speed of the other shaft is set to a preset value. The present invention is characterized in that an auxiliary mechanism is provided that forcibly closes the reheat steam control valve when the temperature exceeds the limit.

[Embodiments of the invention]

Embodiments of the invention will now be described with reference to the accompanying drawings.

FIG. 1 is a schematic steam/control system diagram of a cross compound reheat turbine equipped with a control device of the present invention. The steam generated from the boiler 1 is passed through the main steam stop valve 2. Steam control valve 3
through which it enters the high pressure turbine 4. The steam discharged from the high pressure turbine 4 is reheated by the reheater 5 and enters the intermediate pressure turbine 8 through the reheat steam stop valve 6 and the controlled intercept valve 7. The steam leaving the intermediate pressure turbine 8 is guided to the low pressure turbine 12, 13, enters the condenser 15, and is condensed.

The primary turbine is composed of a high pressure turbine 4, an intermediate pressure turbine 8, and a primary turbine generator 9, and the secondary turbine is composed of a low pressure turbine 12.11=secondary turbine generator 14. Primary turbine generator 9 and secondary turbine generator 14
Yes, the electricity is sent outside. The rotational speed signals from the rotational speed detector 10 that detects the rotational speed of the primary turbine shaft and the rotational speed detector 11 that detects the rotational speed of the secondary turbine shaft are input to the control device 16, which outputs the steam that controls the main steam. It drives the control valve 3 and the intercept valve 7 that controls reheated steam.

In a cross compound turbine power plant,
Usually, the primary turbine generator (9 in this example) and the secondary turbine generator (14 in this example) are electrically coupled and operated synchronously. The same applies to this example.

Based on the signal detected by the rotation speed detector 10 of the primary turbine, the control device 1ii) 16 controls the opening and closing of the steam control valve 3 and the intercept valve 7, thereby controlling the rotation speed of the primary turbine. Ru. When the steam flow rate of the intermediate pressure turbine 8 is increased by 151j1'i\il by opening and closing the intercept valve 7, the steam flow rate of the low pressure turbines 12 and 13 connected downstream thereof is also controlled accordingly.

゛ In the cross compound turbine power generation plant configured in this way, when load shedding occurs, the generator 9
．． 14's output decreases rapidly. Therefore, if steam continues to be supplied as it is, the rotation speeds of both the primary and secondary turbines will rise rapidly. In such a case, the rotation speed is detected by the detector 10, and when the rotation speed exceeds the following value, the steam control valve 3 and the intercept valve 7 are closed. The increase in rotational speed is required by law to be 111% or less of the rated rotational speed. On the other hand, a detector 11 detects an increase in the rotational speed of the secondary turbine, and when the rotational speed exceeds a specified rotational speed, a signal is applied to the control device 16 to close the intercept valve 7. As a result, when the electrical connection between the primary turbine generator 9 and the secondary turbine generator 14 is cut off,
This makes it possible to suppress the increase in turbine rotational speed.

The block diagram of the control device 16 outlined in FIG. 1 is shown in FIG.
As shown in the figure. Signal 17 of the rotation speed detector 10 of the primary turbine
enters the velocity function function 18. This output 19 becomes a valve opening signal υ and enters a valve opening setting function 20. The output 21 is transmitted to the drive section 22 of the steam control valve 3. -force signal 17
Enters another speed function function 23. This output signal 2
4 enters the low value priority circuit 25, and its output 26 enters the valve opening degree setting function 27. Its output 28 is the intercept valve 7
The signal is transmitted to the moving part 29. Secondary turbine rotation speed detector 110 rotation speed signal 30 enters speed function function 31)
Output 32 is transmitted to low value priority circuit 25. The speed function function 18 indicates that the turbine speed 17 is 100% compared to the rated rotation speed.
%, the valve opening is 100%, and the fully closed signal is 0% at 105% speed.
It is a function of The speed function function 23 is the turbine speed 1
When the speed is 00%, the opening is 100%, when the speed is 105%, the opening is 100%, and when the speed is 107%, it is a function of the fully closed signal 0%. The speed function function 31 has a 100% opening when the speed is 107% or less, and a fully closed signal of 0% when the speed is 107% or more. The low value priority circuit 25 selects the lower valve opening signal between the signal 24 and the signal 32.

FIG. 3 shows the function of the low value priority circuit 25.

The horizontal axis shows the rotation speed, and the vertical axis shows the valve opening. When signals 24 and 32 are input, the output of the low value priority circuit is signal 26.
becomes. When the speed is 107% or more, there is a double valve closing signal.

FIG. 4 is a control system diagram showing a specific example of a mechanical/hydraulic control device configured to have the functions shown in FIG. 2.

In this figure, the control hydraulic pressure is indicated by an arrow P, and the steam flow controlled by the intercept valve 7 is indicated by a broken line arrow.

10.11 schematically depicts the speed detector shown in FIG. 2, and in this embodiment, a mechanical rotation detector composed of a centrifugal weight and a rotary pilot valve is used. By using this type of mechanical rotation detector, the rotational speed of the object to be measured can be converted into a hydraulic signal with high fidelity and quick response, which is advantageous and allows the effects of the present invention to be fully demonstrated. easy. When the rotational speed increases to a value higher than the rotational speed set by the rotational speed setting 33, the pilot 34 moves downward, drains the oil from the speed relay 35, and the piston of the speed relay 35 moves downward. When the piston of the speed relay 35 moves downward, the steam control valve and intercept valve are set to move in the closing direction. speed relay 3
5 moves the control valve drive by lever 36. On the other hand, the lever 37 serves as a signal for operating the hydraulic transmink 38. The lower cylinder hydraulic pressure of the hydraulic transmitter 38 is set to be proportional to the stroke of the speed relay 35. The hydraulic pressure from the hydraulic transmitter 38 is transmitted to the hydraulic receiver 40 through the entire piping 39. The hydraulic receiver 40 is set to stroke in proportion to the hydraulic pressure generated by the hydraulic transmitter 38. The stroke of the hydraulic receiver 40 moves the pilot valve of the piston 41, and the piston 41 operates the lever 42. The lever 42 operates the pilot 43 to operate the hydraulic cylinder 29 of the intercept valve 7. This causes the intercept valve to operate depending on the rotational speed.

On the other hand, another speed detector 11 is installed in the secondary turbine, and a hydraulic transmitter piping 39 is connected to this pilot 44. The hydraulic pressure is not released until the speed reaches 107%, and when the speed increases to 107%, the hydraulic pressure in the piping 39 is released by the movement of the pilot 44, and the output hydraulic pressure of the hydraulic transmitter 38 is set to zero.
fully close.

FIG. 5 shows an embodiment different from the above (FIG. 4).

The difference from the previous example is that an upper cylinder 46 is interposed and connected in the middle of the rond connecting the lever 42 and the pilot 43.

The upper cylinder 46 has a structure in which a piston rod contracts when pressure oil is supplied to its lower hydraulic chamber, and when the pressure oil is drained, the piston rod is expanded by a built-in spring.

Under normal operating conditions, hydraulic pressure is supplied to the upper cylinder 46 of the pilot valve 43 via the port of the pilot 44 of the speed detector 11 of the secondary turbine. Normally, the piston 41 is operated by a signal from the hydraulic receiver 40, and the lever 42 is operated. Since oil pressure is supplied to the cylinder 46, the pilot 43 moves in response to the lever 42. Here, when the rotational speed of the secondary turbine increases, oil pressure is drained from the pilot 44 and the cylinder 46
The lower hydraulic pressure is released, and only the pilot valve 43 is moved downward by the spring to Dlb<. This closes the intercept valve 7 and prevents overrun of the secondary turbine.

〔Effect of the invention〕

As described in detail above, the present invention provides a rotation speed detector on one shaft of a cross compound reheat turbine, and based on the detection result of the detector, the main steam In a mechanical/hydraulic control device that opens and closes a steam control valve, when the other shaft is provided with a rotation speed detector different from the above, and the rotation speed of the other shaft exceeds a preset value. By providing an auxiliary control mechanism for forcibly closing the reheat steam control valve, it is possible to configure a mechanical/hydraulic control device that is free from hunting or overrun. It has practical effects.

[Brief explanation of the drawing]

FIG. 1 is a steam/control system diagram of a cross compound turbine power plant equipped with one example of the control device of the present invention.
FIG. 2 is a block diagram of the control device in the above system diagram, FIG. 3 is a diagram showing the same performance, and FIG. 4 is a control system diagram of the same. FIG. 5 is a control system diagram of an embodiment different from the above. DESCRIPTION OF SYMBOLS 1... Boiler, 2... Main steam stop valve, 3... Steam control valve, 4... High pressure turbine, 5... Reheater, 6...
... Reheat steam stop valve, 7... Intercept valve for controlling reheat steam, 8... Medium pressure turbine, 9... Generator, 10.11... Rotation speed detector, 12.13 ...Low pressure turbine, 16...Control device, 20...Valve opening setting function, 23...Speed function setting function, 25...Low value priority circuit, 29...Hydraulic cylinder, 34... ...Pilot, 35...Speed relay, 36,37...
Lever, 38... Transmitter, 40... Hydraulic receiver, 41... Piston, 42... Lever, 43
．． 44...Pilot valve, 46...Upper cylinder. Kaya 2 Japanese tea 3 Prisoner recovery Japanese art collection (7-)

Claims (1)

[Claims] 1. A machine that includes a rotation speed detector on one shaft of a cross compound reheat turbine and opens and closes a main steam control valve and a reheat steam control valve based on the detection results of the detector. - In a hydraulic control device, a rotation speed detector ° different from the above is provided on the other shaft, and when the rotation speed of the other shaft exceeds a preset value, the reheat steam control valve is forcibly activated. A control device for a cross compound turbine, characterized in that it is provided with an auxiliary control mechanism that causes a valve to close. 2゜The rotation speed detector described above consists of a centrifugal weight and a rotating piston.
2. The control device for a cross compound turbine according to claim 1, wherein the control device is a mechanical detector constituted by a rot valve.