JPH0772491B2 - Pre-warming device for steam turbine - Google Patents

Description

Description: [Object of the Invention] (Industrial field of use) The present invention relates to a pre-warming device for a steam turbine, and more particularly to a steam turbine in which a high-pressure turbine or the like is pre-warmed by auxiliary steam. Prewarming device.

(Prior Art) Generally, when starting a steam turbine, a temperature difference occurs between the temperature of the driving steam supplied to the high-pressure turbine and the temperature of the casing of the turbine, the temperature of the metal parts such as the rotor, and the like causes thermal stress in the casing. . This thermal stress is particularly large when the steam turbine is stopped and restarted for a long time, and when the steam turbine is started in the presence of this thermal stress, the life of the casing, rotor, etc. is shortened.

Therefore, pre-warming is performed in advance by supplying auxiliary steam to the steam turbine etc. to reduce the temperature difference between the temperature of the driving steam and the temperature of the metal parts such as the casing, so that thermal stress at the time of startup is not generated. It

This prewarming is usually performed by the method shown in FIG. That is, the steam turbine plant is a boiler 1
0, a high-pressure turbine 11, and a medium-pressure / low-pressure turbine 12 and the like connected thereto are provided. The high-temperature steam generated by the boiler 10 is supplied to the high-pressure turbine 11 via the main steam pipe 13 and the regulator valve 14 and used for high-speed rotation of the rotor 15. The steam working in the rotor 15 becomes low pressure and low temperature, and is sent to the reheater 17 via the low temperature reheat pipe 16 to be reheated.
This reheated steam is further processed by the high temperature reheat pipe 18, the intercept valve.
It is supplied to the intermediate pressure / low pressure turbine 12 and the like via 19 and after doing work in this intermediate pressure / low pressure turbine 12, it is condensed in a condenser not shown.

An auxiliary steam generator 21 for prewarming is connected to the low temperature reheat pipe 16 near the exhaust port of the high-pressure turbine 11 via an auxiliary steam supply pipe 20. A stop valve 22 for shutting off the supply of the auxiliary steam and a regulating valve 23 for controlling the supply pressure of the auxiliary steam are separately attached to the auxiliary steam supply pipe 20.

Further, the auxiliary steam supply pipe 20 is provided with a pressure detector 24 which detects the auxiliary steam pressure in the vicinity of the high pressure turbine 11. The pressure detection signal of the pressure detector 24 is the pressure control device 25.
When the detected pressure signal is higher than 7.0 gauge pressure (hereinafter, "gauge pressure is referred to as ATG"), the regulating valve 23 is throttle-controlled, and when the detected pressure signal is lower than 6.8 ATG, the regulating valve 23 is controlled. The opening control is performed and the auxiliary steam pressure supplied to the high-pressure turbine 11 is controlled to be a predetermined pressure. Furthermore, a temperature detector 26 that detects the temperature of the rotor 15 of the high-pressure turbine 11 is attached. The temperature detection signal of the temperature detector 26 is sent to the temperature control device 27, and if the detected temperature signal is 150 ° C. or less, the stop valve 22 is opened,
Auxiliary steam is supplied to the high-pressure turbine 11, and the detected temperature signal
If the temperature is 158 ° C or higher, the stop valve 22 is closed and the high pressure turbine 11
The auxiliary steam supplied to the is shut off.

Reference numerals 28 and 29 denote drain valves provided between the high pressure turbine 11 and the reheater 17, and between the reheater 17 and the intercept valve 19, and discharge drain water generated during prewarming. To do.

The pre-warming of this steam turbine will be described. This pre-warming is generally performed in a portion of the driving steam and the steam turbine where the temperature difference is largest, that is, in the high pressure turbine 11.

When performing this pre-warming, first, adjust valve 14
And the intercept valve 19 are closed, and the main steam supplied from the boiler 10 to the high-pressure turbine 11 is stopped.

Next, the pressure control device 25 and the temperature control device 27 are operated.
First, the temperature detector 26 detects the temperature of the rotor 15,
The detected temperature signal is sent to the temperature control device 27. Since this detected temperature signal is 150 ° C. or lower because it is a low temperature at the time of startup, the temperature control device 27 sends an opening operation signal to the stop valve 22 to open the stop valve 22.

On the other hand, the pressure detector 24 detects the auxiliary steam pressure supplied to the high-pressure turbine 11, and the detected pressure signal is sent to the pressure control device 25. This detected pressure signal is 6.8 ATG because the auxiliary steam is not supplied to the high pressure turbine 11.
Since it is lower, an opening operation signal is sent from the pressure control device 25 to the adjusting valve 23, and the opening control of the adjusting valve 23 is performed.

Auxiliary steam is supplied from the auxiliary steam generator 21 to the high-pressure turbine 11 by the opening control of the adjusting valve 23 and the opening operation of the stop valve 22. Since this supply auxiliary steam is initially cooled by the casing of the high-pressure turbine 11, the low temperature part such as the rotor 15,
It becomes drain water and is discharged from drain valves 28 and 29. After a short time, the temperature of the casing of the high-pressure turbine 11 is raised, the amount of drainage of auxiliary steam is reduced, and the auxiliary steam pressure is also reduced.
The pressure becomes high up to 6.8 ATG. This state is continued for a while, the pressure of the high pressure turbine 11 is 7.0 (ATG), the rotor
It is performed until the temperature of 15 degrees reaches about 150 ° C.

When the temperature of the rotor 15 etc. reaches 158 ℃ or higher, the temperature detector 26
The temperature control circuit 27 is controlled by this temperature signal to close the stop valve 22, the auxiliary steam to be supplied to the high-pressure turbine 11 is supplied, and the pre-warming of the high-pressure turbine 11 is completed.

When the pre-warming is completed, the regulator valve 14 and the intercept valve 19 are opened, the main steam is supplied from the boiler 10 to the high pressure turbine 11, and the operation of the high pressure turbine 11 etc. is started.

(Problems to be Solved by the Invention) In prewarming of a high-pressure turbine or the like, high-pressure auxiliary steam generated from an auxiliary steam generator is supplied to a high-pressure turbine or the like while being controlled by a regulating valve and a stop valve, and a casing or the like has a predetermined size. The pressure is adjusted to reach a predetermined temperature.

In order to effectively carry out this pre-warming, it is necessary to maintain the high-pressure auxiliary steam at an accurate value. For example, if the auxiliary steam pressure of the high-pressure turbine or the like is too low, pre-warming is delayed, while if it is too high, it adversely affects the thrust bearing portion of the turbine.

However, generally, in this prewarming, most of the auxiliary steam supplied to the high-pressure turbine or the like is initially cooled by the high-pressure turbine or the like into drain water, and even if the adjustment valve is fully opened, it takes time to reach a predetermined pressure. Takes. Further, the auxiliary steam pressure gradually increases as the temperature of the casing, the rotor, etc. increases, but the regulating valve may be slowly throttled so as to respond to the increase in the auxiliary steam pressure.

On the other hand, since a normal regulating valve catches pressure fluctuations such as auxiliary steam pressure and quickly responds to the pressure fluctuations, it is almost necessary for slow motion control such as pre-warming. Not functioning. In particular, this type of regulating valve is considerably expensive because its precise function is required for its purpose, and when it is installed in a pre-warming device, it is not satisfactory in terms of cost efficiency.

Further, since the stop valve controls the cutoff of the auxiliary steam supplied from the auxiliary steam generator to the high-pressure turbine, the auxiliary valve may be stopped accurately even if the operation is slow.

In consideration of the above points, in prewarming of a high-pressure turbine or the like, if a control function is provided for the opening / closing function of the operation of the stop valve, it is possible to achieve the purpose without using an expensive control valve with precision operation. .

In order to solve the above problems, the present invention provides a pre-warming device for opening and closing auxiliary steam by a stop valve and controlling the auxiliary steam to achieve the object without using an expensive and precise control valve. It is in.

[Structure of Invention]

(Means for Solving the Problems) The present invention provides a steam turbine in which auxiliary steam having a predetermined set pressure and a predetermined set temperature is supplied to a high-pressure turbine or the like, and the high-pressure turbine or the like is pre-warmed by the auxiliary steam. In the pre-warming device, the auxiliary steam generator provided so as to supply the auxiliary steam to the high-pressure turbine, and the auxiliary steam generator provided between the auxiliary steam generator and the high-pressure turbine And a stop valve for shutting off the auxiliary steam to be supplied to the high pressure turbine and the like, and a pressure detection for detecting the pressure of the auxiliary steam supplied to the high pressure turbine etc. provided between the stop valve and the high pressure turbine etc. And a pressure setting signal detected by this pressure detector are compared with a pressure setting signal, and when the output signal continues for a predetermined time, the stop valve is opened and closed by a fixed amount. And a pressure control circuit adapted to control.

(Operation) Auxiliary steam generated from the auxiliary steam generator is supplied to the high-pressure turbine via the stop valve, and the temperature and pressure of the high-pressure turbine are increased. The supply pressure of this auxiliary steam is detected by a pressure detector, the detected pressure signal is compared with a preset pressure setting signal, and if the output signal continues for a predetermined time, the stop valve is controlled to open or close by a fixed amount. To do. By this control, auxiliary steam having a predetermined temperature and a predetermined pressure is supplied to the high-pressure turbine to pre-warm the high-pressure turbine.

(Embodiment) An embodiment of a pre-warming device for a steam turbine of the present invention will be described below with reference to FIG. In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

A stop valve 30 is provided on the auxiliary steam supply pipe 20 of the auxiliary steam generator 21 to shut off the auxiliary steam supplied from the auxiliary steam generator 21 to the high-pressure turbine 11 and control the supply pressure thereof. A control circuit 31 is connected to the stop valve 30, and opening / closing is controlled by a pressure signal detected by the pressure detector 24 and a temperature signal detected by the temperature detector 26.

The control circuit 31 includes a temperature control unit 32 that receives a temperature signal detected by the temperature detector 26 and shuts off the stop valve 30 by the detected temperature signal, and a stop valve by a pressure signal detected by the pressure detector 24.
An aperture control circuit 33 for controlling the aperture of 30 and an opening control circuit 34 for controlling the aperture are provided.

The temperature control unit 32 receives the temperature detection signal of the rotor 15 detected by the temperature detector 26, and this temperature detection signal is compared with the temperature setting signal of a temperature setter (not shown) incorporated in the temperature control unit 32. The temperature setting signal of this temperature setting device is the same as the temperature control device 27 of FIG. 2, the stop valve 30 is opened when the temperature of the temperature detection signal is 150 ° C. or less, and the stop valve 30 is opened when the temperature of the temperature detection signal is 158 ° C. or more. Is closed.

The throttle control circuit 33 and the opening control circuit 34 are similar in electric circuit, and these control circuits 33 and 34 are pressure detectors.
The auxiliary steam pressure signal detected by 24 is received, and the stop valve 30 is opened / closed by this auxiliary steam pressure signal. That is, the throttle control circuit 33 controls the stop valve 30 to be closed. The throttle control circuit 33 is provided with a comparator 35a for comparing the auxiliary steam pressure signal detected by the pressure detector 24 and the set pressure signal of the pressure setter 36a. The pressure setter 36a is configured to generate a set pressure signal of 7.2 (ATG) or 7.0 + 0.2 (ATG) (0.2 (ATG) is a margin value), and this signal is constantly sent to the comparator 35a. In the comparator 35a, when the auxiliary steam pressure signal sent from the pressure detector 24 is received, it is compared with the set pressure signal, and when the auxiliary steam pressure signal exceeds the set pressure signal, an output signal, for example, a pulse signal (+1) is output. To be done.

When the comparator 35a outputs a pulse signal, this pulse signal is sent to the first timer circuit 38a via the first wipeout circuit 37a. The first timer circuit 38a is configured to output a pulse signal after one minute when receiving the pulse signal from the first wipeout circuit 37a, and the pulse signal is output to the second wipeout circuit 39a and the second wipeout circuit 39a. 2 timer circuit 4
It is sent simultaneously with 0a. The second timer circuit 40a is configured to output a pulse signal after 10 seconds when receiving the pulse signal, and the pulse signal is sent to the second wipeout circuit 39a and the first wipeout circuit 37a at the same time. To be
Therefore, the output signal of the second wipeout circuit 39a is controlled by the pulse signal of the comparator 35a, and this pulse signal is sent to the stop valve 30 for 10 seconds in 1 minute, and the stop valve 30 for 10 seconds has a predetermined value. Is operated by the amount of.

When the first wipeout circuit 37a receives the pulse signal of the comparator 35a and the pulse signal of the second timer circuit 40a,
When the output pulse signal is blocked and the pulse signal of the comparator 35a is received but the pulse signal of the second timer circuit 40a is not received, the output pulse signal is output. The operation of the second wipeout circuit 39a is similar to that of the first wipeout circuit 37a. However, the input signal uses the output pulse signal of the first timer circuit 38a instead of the pulse signal of the comparator 35a,
The difference is that the output signal of the second timer circuit 40a is used as the second output pulse signal.

Since the opening control circuit 34 is the same as the aperture control circuit 33 as described above, the parts corresponding to the respective components of the aperture control circuit 33 are denoted by the reference characters b, and the description thereof will be omitted. However, the set pressure signal of the pressure setter 36b is 6.8 (ATG) or 7.0-0.2
(ATG) is set, and this set pressure signal is constantly output by the comparator 35b.
And the auxiliary steam pressure signal sent from the pressure detector 24 is lower than the set pressure signal, a deviation pulse signal (+1) is output. Further, when the pulse signal of the second wipeout circuit 39b is output, there is a difference that the stop valve 30 is opened only during the time when the pulse signal is received.

Pre-warming in the high-pressure turbine 11 thus configured will be described.

First, the regulator valve 14 and the intercept valve 11 are closed, and the control circuit 31 is energized in this state. Due to this bias, the temperature of the rotor 15 is detected by the temperature detector 26, and the temperature signal is sent to the temperature controller 32. This temperature detection signal is
Since the temperature of 15 is lower than the main steam temperature, an output signal is sent from the temperature control section 32 to the stop valve 30, and the stop valve 30 is opened.

When the pressure detector 24 detects the auxiliary steam pressure, the detected pressure signal is sent to the comparators 35a and 35b. Since the detected pressure signal at the time of start-up is a low pressure signal at the beginning of prewarming, it is compared with the set pressure signal of the comparator 35b, and the deviation pulse signal of the comparator 35b is sent to the first wipeout circuit 37b. .

Since the first wipeout circuit 37b has not yet received the pulse signal of the second timer circuit 40b, the pulse signal is sent to the first timer circuit 38b. The first timer circuit 38b outputs a pulse signal after 1 minute, and the pulse signal is simultaneously sent to the second timer circuit 40b and the second wipeout circuit 39b.

When the second wipeout circuit 39b receives the pulse signal,
The pulse signal from the second wipeout circuit 39b causes the stop valve 30
Sent to. The stop valve 30 receives the pulse signal,
While receiving this pulse signal, the stop valve 30 is controlled to open by a fixed amount.

After a lapse of 10 seconds, the second timer circuit 40b operates and the pulse signal output from the second timer circuit 40b causes
The pulse signal of the second wipeout circuit 39b is blocked,
The opening adjustment of the stop valve 30 is stopped.

Therefore, if the stop valve 30 keeps the detected pressure lower than the set pressure for 1 minute, it receives a pulse signal for 10 seconds only during the 1 minute, and the stop valve 30 is controlled to open a certain amount by this 10 second pulse signal. Then, the auxiliary steam corresponding to the opening degree is supplied to the high-pressure turbine 11.

In addition, the pulse signal of the second timer circuit 40b is the first
Is also sent to the first wipeout circuit 37b, and the pulse signal of the first wipeout circuit 37b is blocked. As a result, the first timer circuit 38b is deenergized, and the series of opening operations of the stop valve 30 is completed.

Next, the adjusted auxiliary steam pressure is detected by the pressure detector 24. This detected pressure signal is the comparator
At 35b, the pressure is compared with the set pressure signal of the pressure setter 36b, and if it is lower than the set pressure, the above operation is further performed and the stop valve 30 is opened.

Such an operation is repeated several times until the set pressure of the auxiliary steam supplied to the high-pressure turbine 11 becomes 6.8 (ATG) or higher.

Also, with this control, the auxiliary steam pressure of the high-pressure turbine 11 is 7.2A.
When it becomes TG or more, the pressure signal detected by the pressure detector 24 is sent to the comparators 35a and 35b of the throttle control circuit 33.
Since this detected pressure signal is a high pressure signal, the comparator 35
The set pressure signal of a is compared, and the pulse signal is sent to the first wipeout circuit 37a. First wipeout circuit 3
In 7a, the pulse signal causes the first timer circuit 38a and the second timer circuit 38a to
The timer circuit 40a and the second wipeout circuit 39a are sequentially operated, and the stop valve 30 is closed and a pulse signal is sent. While the pulse signal is being sent, the stop valve 30 is operated to be closed by a certain amount, and the auxiliary steam supplied from the auxiliary steam generator 21 to the high pressure turbine 11 is limited. The subsequent operation is the same as the diaphragm operation.

In this way, the high pressure turbine 11 has an auxiliary steam pressure of 6.
It is maintained at 8 to 7.2 (ATG), and the casing, rotor, etc. of the high-pressure turbine 11 are warmed to a high temperature at a predetermined pressure.

After this warming is done for a while, the casing,
Rotor temperature is close to 158 ℃. This temperature is detected by the temperature detector 26, and the detection signal is sent to the temperature controller 32. An output signal is output from the temperature control unit 32 by this detection signal, the stop valve 30 is closed by the output signal, and the auxiliary steam supplied to the high-pressure turbine 11 is shut off. This completes the prewarming of the high-pressure turbine 11.

When the pre-warming is completed, the regulator valve 14 and the intercept valve 19 are opened, and the high pressure steam is fed from the boiler 10 to the high pressure turbine 11
To the normal start-up operation.

Therefore, in the high-pressure turbine 11, even if it receives high-pressure steam, the casing, the rotor, and the like are maintained at a high temperature by pre-warming, so that thermal stress does not occur.

Although the throttle control circuit and the timer circuit of the opening control circuit are set to 1 minute and 10 seconds in the above embodiment, they can be used by arbitrarily changing them according to the capacity, performance, purpose, etc. of the high pressure turbine, stop valve, auxiliary steam supply device. To be done.

Further, although the operation of the first wipeout circuit, the first timer circuit and the like is performed by the pulse signal, the same operation can be performed by operating by the analog signal instead of the pulse signal.

Further, in the above-described embodiment, the case where the auxiliary steam for prewarming is supplied to the high-pressure turbine has been described, but the main steam is also used for prewarming of a medium-pressure turbine or the like.

〔The invention's effect〕

In the pre-warming device of the steam turbine of the present invention, when the auxiliary steam generated from the auxiliary steam supply device is supplied to the high-pressure turbine, the auxiliary steam pressure is detected by the pressure detector, and the detected pressure signal and the preset pressure signal are set in advance. The set pressure signal is compared, and when the output signal continues for a predetermined time, the stop valve is controlled to open and close by a fixed amount, so auxiliary steam for pre-warming that has a slow pressure change is coordinated by the stop valve. It can be controlled precisely.

Also, because the stop valve has an opening / closing function and a control function,
It is possible to simplify the control device without using a highly accurate and expensive control valve.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a pre-warming device of a steam turbine of the present invention, and FIG. 2 is a block diagram showing a main part of a pre-warming device of a steam turbine that has been generally used conventionally. is there. 10 …… boiler, 11 …… high pressure turbine, 12 …… medium / low turbine, 13 …… main steam pipe, 14 …… control valve, 15 …… rotor, 16 …… low temperature reheat pipe, 17 …… reheat Heater, 18 ... High temperature reheating pipe, 19 ... Intercept valve, 20 ... Auxiliary steam supply pipe, 21 ... Auxiliary steam generator, 22, 30 ... Stop valve, 23 ...
Adjusting valve, 24 Pressure detector, 25 Pressure control device, 26
...... Temperature detector, 27 ...... Temperature control device, 28,29 ...... Drain valve, 31 ...... Stop valve control device, 32 ...... Temperature detection unit, 33 ...
… Aperture control circuit, 34 …… Opening control circuit, 35a, 35b …… Comparator, 36a, 36b …… Setting device, 37a, 37b …… First wipeout circuit, 38a, 38b …… First timer circuit , 39a, 39b ……
Second wipeout circuit, 40a, 40b ... Second timer circuit.

Claims (1)

[Claims] 1. A prewarming device for a steam turbine, wherein a high pressure turbine or the like is supplied with auxiliary steam at a predetermined set pressure and a predetermined set temperature to prewarm the high pressure turbine or the like. To the auxiliary steam generator provided to supply the auxiliary steam to the high pressure turbine and the interruption of the auxiliary steam provided from the auxiliary steam generator to the high pressure turbine and the like. A stop valve to control the auxiliary steam pressure,
A pressure detector, which is provided between the stop valve and the high-pressure turbine and detects the pressure of the auxiliary steam supplied to the high-pressure turbine, compares the detected pressure signal and the pressure setting signal detected by the pressure detector, A pre-warming device for a steam turbine, comprising a pressure control circuit configured to open and close the stop valve by a constant amount when an output signal continues for a predetermined time.