JP6121192B2 - Steam turbine gland seal device - Google Patents

Description

  The present invention relates to a gland seal device for a steam condensing turbine, and more particularly, to a gland seal device for using a gland seal steam for sealing a gland portion while reducing the pressure at a turbine inlet.

  Normally, in a condensing steam turbine, since the degree of vacuum in the turbine casing is maintained even when the turbine is stopped, seal steam is supplied to the gland and air or the like enters from the outside. This prevents the degree of vacuum in the passenger compartment from decreasing.

  This turbine ground seal steam is often used with the turbine inlet steam being decompressed, but when this turbine inlet steam is decompressed, the main steam stop valve is turned off when a turbine trip occurs from the operating state. If the generator is disconnected and the generator is disconnected, the main steam control valve is slightly opened in order to make it in a no-load operation state, so that the gland seal steam cannot be obtained sufficiently and the gland seal performance deteriorates. There was a problem.

  In the case of a steam turbine operated at a constant pressure, the steam pressure at the turbine inlet is constant, so it is easy to ensure the required seal steam pressure when a turbine trip or generator disconnection occurs from the operating state. It is.

  However, in the case of a steam turbine operating in a transformer operation, since the steam pressure at the turbine inlet changes, the control region of the seal steam pressure via the seal steam pressure control valve changes. For this reason, it is difficult to maintain the seal steam pressure at a predetermined pressure when a turbine trip or a generator disconnection occurs from the operating state.

  For this reason, even in the case of a transformer-operated turbine in which the steam pressure at the turbine inlet changes, it is possible to control the steam steam pressure to be constant while suppressing fluctuations in the seal steam pressure during a transient when a turbine trip or generator disconnection occurs from the operating state. It was requested to do.

In addition, patent document 1 (Unexamined-Japanese-Patent No. 2010-209858) can be mentioned as an example which uses turbine inlet-steam steam for turbine inlet steam.
1 and 2, etc. of Patent Document 1 disclose a steam turbine device, which is provided with a high-pressure turbine and a low-pressure turbine, and supplies steam to each ground seal or recovers steam from each ground seal portion to condensate water. There is disclosed a configuration in which the main steam led from the high-pressure turbine to the low-pressure turbine is branched and supplied by the seal steam to the ground seal portion of the low-pressure turbine.

JP 2010-209858 A

  Patent Document 1 discloses a configuration in which the seal steam to the ground seal portion of the low-pressure turbine branches and supplies the main steam guided from the high-pressure turbine to the low-pressure turbine. There is no disclosure until it is possible to control the supply of the seal steam pressure to the gland seal part at the time of a transition such as a generator disconnection, and to enable stable control of the seal steam pressure in a turbine in a transformer operation.

  In addition, as described above, in the case of a steam turbine operating in a transformer operation, the steam pressure at the turbine inlet changes, so when a turbine trip or generator disconnection occurs during operation, the seal steam pressure is efficiently maintained at a constant pressure. Therefore, stable control of the seal steam pressure during a turbine trip or a generator disconnection in a transformer-operated turbine has been required.

  Therefore, in view of the above problems, the present invention is a steam turbine for transformer operation in which the turbine ground seal steam is used while the turbine inlet steam is depressurized. An object of the present invention is to provide a ground seal device for a steam turbine which can improve the controllability of the seal steam pressure by maintaining the seal steam pressure at a constant pressure when the generator is disconnected.

In order to solve such a problem, the present invention provides a gland seal steam for sealing a gland portion of a steam turbine, and a gland seal apparatus for a steam turbine that uses a turbine inlet steam under reduced pressure.
When the steam turbine is shut down suddenly by shutting off the main steam flow into the steam turbine, or when the generator driven by the steam turbine is disconnected from the power system and the steam turbine is operated without load, A main steam control valve that controls the inflow of main steam, a seal steam branch passage that branches from the upstream side of the main steam control valve and guides the seal steam to the ground portion, and is provided in the seal steam branch passage, A seal steam pressure control valve that controls a seal steam pressure acting on the gland portion; and a seal steam control device that controls an opening degree of the seal steam pressure control valve. A target control unit for controlling the opening degree of the seal steam pressure control valve so as to maintain the seal steam pressure at a constant target pressure, and when the steam turbine is suddenly stopped or the generator is connected to the power system. In at least one of cases where the steam turbine is disconnected and operated without load, the opening degree of the seal steam pressure control valve is variably controlled to the opening degree corresponding to the main steam pressure upstream of the main steam control valve. to a transient control unit, it has a, wherein the opening control of the steam seal pressure control valve by transient control unit is performed by a predetermined time and then is characterized in that control of the target controller is performed.

  In the case of a turbine trip that shuts down the steam turbine by shutting off the main steam flow to the steam turbine, or in the case of a generator disconnection that disconnects the generator from the power system and operates the steam turbine without load However, in order to maintain the degree of vacuum in the turbine casing in the ground part, it is necessary to supply seal steam to the ground part to prevent air from entering from the outside to reduce the degree of vacuum in the turbine casing. There is.

  In the present invention, a seal steam branch passage that branches from the upstream side of the main steam control valve and guides the seal steam to the ground portion, and is provided in the seal steam branch passage to control the seal steam pressure to the ground portion. A seal steam pressure control valve, and a seal steam control device that controls the opening degree of the seal steam pressure control valve. The seal steam control device is configured to stop the steam turbine or to remove the generator from the power system. In at least one of the cases where the steam turbine is in a no-load operation in a row, the opening degree of the seal steam pressure control valve is variably controlled to an opening degree corresponding to the main steam pressure upstream of the main steam control valve. Since the transient control unit is provided, the seal steam can be supplied to the gland without being affected by the main steam being blocked or slightly opened by the main steam control valve.

Further, in this transient control unit, the opening degree of the seal steam pressure control valve is variably controlled to an opening degree corresponding to the main steam pressure upstream of the main steam control valve, so that the main steam pressure is changed to the steam turbine. Even in a steam turbine with a transformer operation that controls output by adjusting the amount of inflow steam, it is possible to control the seal steam pressure to the ground when the turbine trips or the generator is disconnected. Can be improved.
In the present invention, the opening degree control of the seal vapor pressure control valve by the transient control unit is executed for a predetermined time, and thereafter, the control by the target control unit is performed.
That is, the seal steam pressure control valve is opened by the transient control unit for a certain period of time when the turbine trip or generator disconnection occurs and the main steam is not supplied to the turbine to secure the seal steam. The seal steam pressure can be stably controlled by suppressing the fluctuation of the seal steam pressure and then switching to the control to a constant pressure by the target control unit.

  In the present invention, it is preferable that the seal steam control device includes a main steam pressure upstream of the main steam control valve and an opening degree of the seal steam pressure control valve during a turbine trip for suddenly stopping the steam turbine. It is good to have the 1st function setting part which set up relation.

  Thus, since the opening degree of the seal steam control valve at the time of the turbine trip is calculated based on the data of the first function setting unit set according to the main steam pressure on the upstream side of the main steam control valve, It is possible to control the valve opening of an appropriate seal steam control valve in accordance with the main steam pressure.

  In the present invention, it is preferable that the seal steam control device is configured so that the main steam on the upstream side of the main steam control valve at the time of generator disengagement in which the generator is disconnected from the power system and the steam turbine is operated without load. It is good to have the 2nd function setting part which set up the relation between a pressure and the opening of a seal vapor pressure control valve.

  Thus, in order to calculate the opening degree of the seal steam control valve when the generator is disconnected based on the data of the second function setting unit set according to the main steam pressure on the upstream side of the main steam control valve, It is possible to control the opening degree of the seal steam control valve suitable for the main steam pressure when the machine is disconnected.

  In the present invention, it is preferable that the relationship set in the first function setting unit and the relationship set in the second function setting unit are as the main steam pressure upstream of the main steam control valve increases. The opening degree of the seal vapor pressure control valve may be set to be small.

  In this way, the opening degree of the seal steam pressure control valve is decreased as the main steam pressure increases, and conversely, the opening degree of the seal steam pressure control valve is increased as the main steam pressure decreases. Thus, even if a turbine trip or generator disconnection occurs from any operating region, a fixed amount of seal steam can be supplied to the gland, and fluctuations in seal steam pressure can be suppressed.

  In the present invention, it is preferable that the ground leak steam leaked from the steam turbine to the ground portion is supplied to the ground seal passage on the downstream side of the seal steam pressure control valve as the seal steam of the ground portion.

  Thus, at the time of high load of the steam turbine, for example, when the load is 50% or more, the ground leak steam leaking from the ground part on the high pressure side of the steam turbine is used as the seal steam of the ground part, and the downstream side of the seal steam pressure control valve. Therefore, during high load operation, the pressure in the ground seal passage rises and the seal vapor pressure can be secured.

  As described above, according to the present invention, in the case of using the turbine ground seal steam of the steam turbine performing the transformation operation while reducing the pressure of the turbine inlet steam, the turbine is tripped or the generator is disconnected. Even if the inlet pressure fluctuates, the opening degree of the seal steam pressure control valve is changed corresponding to the main steam pressure upstream of the main steam control valve, so that the seal steam pressure can be maintained at a constant pressure, This can improve the controllability of the seal steam pressure.

It is a block diagram which shows embodiment of this invention and shows the whole structure. It is a control block diagram of a seal steam control device. It is explanatory drawing which shows the opening degree characteristic of a seal | sticker vapor pressure control valve. It is explanatory drawing which shows the opening degree characteristic of the seal | sticker vapor pressure control valve at the time of a turbine trip. It is explanatory drawing which shows the opening degree characteristic of the seal | sticker vapor pressure control valve at the time of a generator disconnection.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely descriptions. It is just an example.

FIG. 1 is a block diagram showing the overall configuration of a ground seal device for a steam turbine for condensing type transformer operation according to the present invention.
The turbine 1 has turbine blades 7 attached to a rotating shaft 5 in a turbine casing 3, and a high-pressure side ground portion 9 and a low-pressure side ground portion 11 are disposed at both ends thereof, and the respective grounds. A ground seal fin 13 is disposed in the part. Further, a generator 15 is provided directly connected to the rotating shaft 5.

  On the other hand, main steam is supplied to the turbine 1 through a main steam passage 17 from an appropriate steam generation source in a plant (not shown). The main steam passage 17 is provided with a nozzle flow meter 21 for measuring the flow rate of the main steam (measuring the flow rate by measuring the differential pressure across the nozzle 19), and on the downstream side thereof, the main steam pressure gauge 23 However, on the downstream side, a main steam stop valve 25 and a steam control valve 27 which are main steam control valves are installed in series.

  The present embodiment is a steam turbine that performs a transformation operation. During normal operation, the main steam stop valve 25 is maintained in a fully open state, and the pressure of the main steam is controlled and supplied from a steam generation source (not shown). Output control is performed by adjusting the amount of pressure-controlled main steam inflow by a steam control valve 27.

  The main steam stop valve 25 and the steam control valve 27 are both fully closed or driven by the turbine 1 during a turbine trip that shuts off the turbine 1 by shutting off the flow of the main steam to the turbine 1. When the generator 15 is disconnected from the power system so that the turbine 1 is in a no-load operation, the main steam stop valve 25 is fully opened and the steam control valve 27 is controlled to be slightly opened.

  Further, the main steam supplied to the turbine 1 is discharged after the turbine blade 7 is rotationally driven, and is led to a condenser (not shown) to be condensed and become condensed water.

  A seal steam branch passage 29 is provided which branches on the upstream side of the main steam stop valve 25 and the steam control valve 27 of the main steam passage 17 and guides the ground seal steam to the high pressure side gland portion 9 and the low pressure side gland portion 11. .

  The seal steam branch passage 29 is provided with a seal steam pressure control valve 31 and a seal steam pressure gauge 33 for measuring the steam pressure supplied to the gland portion on the downstream side. Further, the downstream side of the seal steam pressure control valve 31 is a high-pressure side ground seal passage 35 that supplies seal steam to the high-pressure side gland portion 9 and a low-pressure side ground seal passage 36 that supplies seal steam to the low-pressure side gland portion 11. Are connected to each other, and a low pressure side ground seal passage 36 is provided with a thermometer 37 for measuring the temperature of the seal steam supplied to the low pressure side ground portion 11 and a temperature-reduced water injection device 39.

  Further, the temperature-decreasing water that cools the seal steam is controlled by the temperature adjusting valve 42 provided in the temperature-decreasing water passage 41 and is supplied to the temperature-decreasing water injection device 39, thereby detecting the thermometer 37. Based on the value, the seal steam to the low-pressure side gland portion 11 is cooled to a constant temperature.

Further, a discharge passage 40 is provided which branches from the low-pressure side gland seal passage 36 and discharges surplus steam to the condenser via a spillover valve 38. It is collected to a condenser (not shown) through the discharge passage 40 and condensed to become condensate.
The spillover valve 38 is manually set to a constant opening. For example, during high load operation (for example, at 100% load), the seal steam pressure control valve 31 controlled by the pressure detected by the seal steam pressure gauge 33 is set to a pressure that is controlled to be fully closed. . The spillover valve 38 may have an automatic opening setting.

  In the turbine 1 as described above, the main steam generated from a steam generation source (not shown) passes through the main steam passage 17, and the flow rate and pressure are detected by the nozzle flow meter 21 and the main steam pressure gauge 23. It passes through the stop valve 25 and the steam control valve 27 and is supplied into the turbine casing 3 and rotated by the expansion work by the steam with respect to the turbine blade 7 attached to the rotating shaft 5. Then, the rotating shaft 5 is rotated and power is generated by the generator 15. Further, the steam after the expansion work is discharged to a condenser (not shown) and condensed to become condensate.

Further, a part of the main steam passes through the seal steam branch passage 29 and further adjusts the pressure of the seal steam via the seal steam pressure control valve 31, so that the high pressure side ground seal passage 35 and the low pressure side ground seal passage are provided. 36.
Thereafter, the steam is supplied to the high-pressure side gland portion 9 and the low-pressure side gland portion 11 as seal steam, and is collected as recovered steam through the recovery passage 45, through the ground condenser, and then recovered to the condenser.

First of all, at the time of startup,
The main steam stop valve 25 is fully open, and the steam control valve 27 is under rotation speed control and has an intermediate opening. Then, the main steam flows into the turbine 1 and the rotation speed starts increasing. At this time, since the load is still low at the time of start-up, ground leakage steam leaking from the steam turbine 1 to the high-pressure side ground portion 9 is hardly generated.

Therefore, the steam pressure in the high-pressure side gland seal passage 35 and the low-pressure side gland seal passage 36 has an intermediate opening degree so that the seal vapor pressure control valve 31 adjusts the main steam flowing in through the seal vapor branch passage 29. Be controlled. The intermediate opening degree is controlled based on a detection signal of a seal vapor pressure gauge 33 provided on the downstream side of the seal vapor pressure control valve 31 at a constant target pressure, that is, at the high-pressure side gland portion 9 and the low-pressure side gland portion 11. The pressure is controlled to an appropriate pressure (a positive pressure slightly higher than the atmospheric pressure) for preventing air from entering the steam turbine from the outside.
If the sealing steam pressure is low, the sealing performance is insufficient, and if it is too high, the leakage amount of the sealing steam increases.

Next, during "load operation"
The main steam stop valve 25 is fully open, and the steam control valve 27 has an intermediate opening according to the load. The main steam pressure control from a steam generation source (not shown) and the turbine inflow steam amount by the steam control valve 27 are adjusted. Output control corresponding to the load.
In the middle and high load operation, the steam pressure rises and the steam flow rate increases, so that the steam leaks from the gap between the ground seal fin of the high-pressure side gland part 9 and the rotary shaft 5 to the high-pressure side gland part 9.

  The pressure of the ground leak steam leaked to the high pressure side gland portion 9 becomes higher than the pressure of the seal steam supplied from the high pressure side ground seal passage 35. Therefore, the ground leak steam overcomes this and the high pressure side ground seal passage is overcome. And flows into the low-pressure side gland part 11 through the low-pressure side gland seal passage 36.

  At this time, since the pressure in the high-pressure side gland seal passage 35 increases, the detection signal of the seal vapor pressure gauge 33 provided on the downstream side of the seal vapor pressure control valve 31 also rises. The seal vapor pressure control valve 31 is controlled in the valve closing direction. Thus, the seal vapor pressure control valve 31 is fully closed as the load increases while performing pressure control.

Next, during "turbine trip"
In the case of a turbine trip that shuts off the turbine 1 by shutting off the flow of the main steam to the turbine 1, both the main steam stop valve 25 and the steam control valve 27 are rapidly fully closed.
For this reason, the main steam does not flow into the turbine 1. As a result, the ground leak vapor disappears and the pressure in the high-pressure side gland seal passage 35 and the low-pressure side gland seal passage 36 becomes negative.

  At this time, since the detected value of the seal vapor pressure gauge 33 is also lowered, the seal vapor pressure control valve 31 is controlled in the valve opening direction, but the pressure drop in the high pressure side ground seal passage 35 and the low pressure side ground seal passage 36 is detected. Accordingly, the control of the opening direction of the seal vapor pressure control valve 31 is slow. For this reason, in order to respond quickly to securing of the seal steam at the time of the turbine trip, the transient control unit 49 of the seal steam control device 47 described later is controlled so as to be able to respond quickly.

Next, at the time of generator disconnection,
In the case of the generator disconnection in which the generator 15 driven by the turbine 1 is disconnected from the power system and the turbine is operated without load, the flow of main steam into the turbine 1 is controlled to a very small amount.

That is, in the case of the generator disconnection, the main steam stop valve 25 is fully open, the steam control valve 27 is in a slightly open state, and no load control is being performed.
Although the main steam flows into the turbine 1, the ground leak steam leaking from the steam turbine 1 to the high-pressure side gland portion 9 is hardly generated or slightly flows as in the above “start-up”. In this state, the pressure in the high-pressure side ground seal passage 35 and the low-pressure side ground seal passage 36 decreases to the negative side.

  Therefore, similarly to the operation at the time of the turbine trip, the detection of the negative pressure in the high-pressure side gland seal passage 35 and the low-pressure side gland seal passage 36 and the control of the opening direction of the seal vapor pressure control valve 31 accompanying this are slow. For this reason, it controls so that a rapid response | compatibility is possible by the transient control part 49 of the seal | sticker steam control apparatus 47 mentioned later so that a rapid response | compatibility is possible.

Next, the main steam control device 51 that controls the operation of the turbine 1 and the seal steam control device 47 that controls the gland seal steam pressure will be described.
The main steam control device 51 receives the turbine trip signal 53, the generator disconnection signal 55, the signal from the main steam nozzle flow meter 21, and the operation state signal such as the turbine speed and load, and the main steam control device 51 receives the main steam. The operation of the turbine 1 is controlled by controlling the opening degree of the stop valve 25 and the steam control valve 27. That is, by controlling the opening degree of the main steam stop valve 25 and the steam control valve 27 at the time of the above-mentioned “start-up”, “load operation”, “turbine trip”, “generator disconnection”, The operation of the turbine 1 is controlled.
As shown in FIG. 1, the seal steam control device 47 mainly includes a target control unit 57 and a transient control unit 49.

In the target control unit 57, the opening degree of the seal vapor pressure control valve 31 is detected by the seal vapor pressure gauge 33 so as to keep the seal vapor pressure to the high pressure side gland unit 9 and the low pressure side gland unit 11 at a constant target pressure. Based on the value, control is made so that a constant target value is obtained by footback control.
When the steam pressure in the high-pressure side gland seal passage 35 is lower than the target value, the seal steam pressure control valve 31 is opened and main steam is introduced to increase the pressure.

  That is, the target control unit 57 performs control at the time of “starting up” and “at the time of load operation”, and at the time of “starting up”, since the ground leakage steam of the turbine is hardly generated as described above, The steam pressure control valve 31 adjusts the main steam flowing in through the seal steam branch passage 29 to obtain the seal steam pressure, and the detection signal of the seal steam pressure gauge 33 provided on the downstream side of the seal steam pressure control valve 31. Based on this, it is controlled so as to be a constant target pressure.

  Further, in the “load operation”, as described above, during the medium and high load operation, steam leaks to the high-pressure side ground portion 9 to generate ground leak steam, which is based on the pressure of the seal steam supplied from the high-pressure side ground seal passage 35. Since the pressure in the high-pressure side ground seal passage 35 increases and the detection signal of the seal steam pressure gauge 33 provided on the downstream side of the seal steam pressure control valve 31 also increases, the seal steam pressure control valve 31 is closed. Controlled in direction.

  In the transient control unit 49, when the steam turbine 1 is suddenly stopped or when the generator 15 is disconnected from the power system and the turbine 1 is operated without load, the opening degree of the seal steam pressure control valve 31 is rapidly opened. Then, control is performed so as to secure seal steam to the high-pressure side gland portion 9 and the low-pressure side gland portion 11 of the rotating shaft 5 that continues to rotate for a while after the occurrence of the trip or the disconnection.

The opening degree at the time of rapid opening is detected by the main steam pressure gauge 23 in the seal steam branch passage 29, that is, upstream of the main steam stop valve 25 and the steam control valve 27, which are the main steam control valves. It is changed corresponding to the magnitude of the detected value.
Therefore, even in a steam turbine with a transformer operation that performs output control by adjusting the amount of steam flowing into the steam turbine by changing the main steam pressure, the seal steam pressure to the ground during a turbine trip or generator disconnection is kept constant. Therefore, the controllability of the seal steam pressure can be improved.

A control configuration block diagram of the seal steam control device 47 is shown in FIG.
In FIG. 2, when the opening degree signal G to the seal steam pressure control valve 31 that makes the seal steam pressure constant by the target control unit 57 is output and there is no abnormal situation due to turbine trip or generator disconnection, The opening signal G is output as it is as the opening signal Px of the seal vapor pressure control valve 31.
The relationship between the opening signal Px and the opening amount of the seal vapor pressure control valve 31 is proportional as shown in FIG. 3, and the opening corresponding to the opening signal Px is set.

  On the other hand, in the transient control unit 49, when it is received by the generator disconnection signal 55 that the generator 15 is disconnected and becomes in a no-load state, that is, when the generator breaker is opened, The signal rises at the inverting unit 61, for example, an ON signal for 1.5 seconds is output, the selection signal S = 1 is input to the selection unit 63, and the opening signal from the input IN2 is output OUT.

  The opening signal from the input IN2 when the generator is disconnected is calculated based on the relationship of the function F (x) A stored in the first function setting unit 65. In the function F (x) A, as shown in FIG. 4, the horizontal axis is the main steam pressure from the main steam pressure gauge 23, and the vertical axis is the opening degree of the seal steam pressure control valve 31. It may be stored as a map or a function expression.

  Further, when the turbine trip signal 53 that has stopped due to the trip of the turbine 1 is received, for example, an ON signal for 1.5 seconds is output, and the selection signal S = 1 is input to the selection unit 67 and input. The opening signal from IN2 is output OUT.

  The opening degree signal from the input IN2 at the time of the turbine trip is calculated based on the relationship of the function F (x) B stored in the second function setting unit 69. In the function F (x) B, as shown in FIG. 5, the horizontal axis is the main steam pressure from the main steam pressure gauge 23, and the vertical axis is the opening degree of the seal steam pressure control valve 31. It may be stored as a map or a function expression.

The relationship set in the first function setting unit 65 shown in FIG. 4 and the relationship set in the second function setting unit 69 shown in FIG. 5 are as the main steam pressure from the main steam pressure gauge 23 increases. The opening degree of the seal steam pressure control valve 31 is set to be small. Conversely, as the main steam pressure is lowered, the opening degree of the seal steam pressure control valve is increased.
Specifically, as shown in FIG. 4, the first function setting unit 65 is variably controlled in accordance with the main steam pressure within the range of 20% to 50%, and the second function setting unit 69. As shown in FIG. 5, the opening degree is variably controlled in the range of 20% to 55% according to the height of the main steam pressure.

  The maximum opening of the first function setting unit 65 used when the generator is disconnected is set to be smaller than the maximum opening of the second function setting unit 69 used when the turbine trips. At the time of the generator disconnection, there is almost no inflow of main steam, but it is not zero. Therefore, it can be said that Gradleak steam is not zero, and its slight rise is taken into consideration.

  Therefore, even if a turbine trip or generator disconnection occurs from any operating region, it becomes possible to supply a constant amount of the seal steam to the gland section rapidly, suppressing fluctuations in the seal steam pressure and ensuring a stable seal. Make it possible.

  Further, for example, an ON signal for 1.5 seconds is output, the selection signal S = 1 is input in the selection units 63 and 67, and the opening degree signal from the input IN2 is output OUT. The opening degree control of the seal steam pressure control valve 31 is executed for a predetermined time, and thereafter, the control by the target control unit 57 is performed. Therefore, a turbine trip or a generator disconnection occurs, and the main steam is not supplied to the turbine 1. For a certain period of time in a transient state, the transient control unit 49 can rapidly open the seal vapor pressure control valve 31 to secure the seal vapor and suppress the variation of the seal vapor pressure. Thereafter, the target control unit By switching to the control to the target pressure of a constant pressure by 57, the seal steam pressure can be stably controlled.

  According to the above embodiment, the transient control part which controls the opening degree of the seal | sticker steam pressure control valve 31 to the opening degree set corresponding to the main steam pressure of the upstream of the main steam stop valve 25 and the steam control valve 27. 49, without being influenced by the main steam stop valve 25 and the steam control valve 27 inflow control to the turbine 1 during the turbine trip or generator disconnection, In addition, it becomes possible to supply seal steam to the low-pressure side gland portion 11.

  Further, since the transient control unit 49 changes the opening degree of the seal steam pressure control valve 31 in accordance with the main steam pressure on the upstream side of the main steam stop valve 25 and the steam control valve 27, the main steam pressure is changed. It is possible to control the steam pressure of the seal to the ground part at the time of turbine trip or generator disconnection even in a transformer-operated steam turbine that controls output by adjusting the amount of steam flowing into the steam turbine by changing Therefore, the controllability of the seal steam pressure can be improved.

  According to the present invention, when the turbine ground seal steam of a steam turbine that performs a transformation operation is used with the turbine inlet steam being depressurized, the turbine inlet pressure varies when the turbine trips or when the generator is disconnected. However, since the opening degree of the seal steam pressure control valve is changed corresponding to the main steam pressure upstream of the main steam stop valve, the seal steam pressure can be maintained at a constant pressure. Controllability can be improved. Therefore, it is suitable for use in a ground seal steam supply device of a steam turbine in a transformer operation.

1 Turbine (steam turbine)
3 Turbine casing 5 Rotating shaft 7 Turbine blade 9 High-pressure side ground (ground)
11 Low-pressure side ground part (ground part)
15 Generator 17 Main steam passage 23 Main steam pressure gauge 25 Main steam stop valve (main steam control valve)
27 Steam control valve (Main steam control valve)
29 Seal steam branch passage 31 Seal steam pressure control valve 33 Seal steam pressure gauge 35 High-pressure side ground seal passage 36 Low-pressure side ground seal passage 37 Thermometer 38 Spillover valve 39 Decreased water injection device 40 Discharge passage 47 Seal steam control device 49 Transient control Unit 53 Turbine trip signal 55 Generator disconnection signal 57 Target control unit 63, 67 Selection unit 65 First function setting unit 69 Second function setting unit

Claims (6)

In a ground seal device for a steam turbine that uses a ground seal steam for sealing a ground portion of a steam turbine while reducing the pressure at the turbine inlet steam,
When the steam turbine is shut down suddenly by shutting off the main steam flow into the steam turbine, or when the generator driven by the steam turbine is disconnected from the power system and the steam turbine is operated without load, A main steam control valve for controlling the main steam inflow,
A seal steam branch passage that branches from the upstream side of the main steam control valve and guides the seal steam to the gland portion;
A seal steam pressure control valve provided in the seal steam branch passage for controlling the seal steam pressure acting on the gland portion;
A seal steam control device for controlling the opening degree of the seal steam pressure control valve,
The seal steam control device includes a target control unit that controls the opening degree of the seal steam pressure control valve so as to maintain the seal steam pressure to the gland portion at a constant target pressure;
In at least one of the case where the steam turbine is suddenly stopped or the generator is disconnected from the power system and the steam turbine is operated without load, the opening degree of the seal steam pressure control valve is determined as the main steam control valve. of the transient control section for variably controlling, it was closed to the opening degree corresponding to the main steam pressure upstream, opening control of the steam seal pressure control valve according to the transition control unit is performed by a predetermined time, then the target A ground seal device for a steam turbine, which is controlled by a control unit.   The seal steam control device sets a first function in which a relationship between the main steam pressure on the upstream side of the main steam control valve and the opening of the seal steam pressure control valve during a turbine trip for suddenly stopping the steam turbine is set. The ground seal device for a steam turbine according to claim 1, further comprising a portion.   The seal steam control device includes a main steam pressure on the upstream side of the main steam control valve and a seal steam pressure control valve when the generator is disconnected so that the generator is disconnected from the power system and the steam turbine is operated without load. The ground seal device for a steam turbine according to claim 1, further comprising a second function setting unit that sets a relationship with the opening.   The relationship set in the first function setting unit is set such that the opening degree of the seal steam pressure control valve decreases as the main steam pressure upstream of the main steam control valve increases. The ground seal device for a steam turbine according to claim 2.   The relationship set in the second function setting unit is set such that the opening degree of the seal steam pressure control valve decreases as the main steam pressure upstream of the main steam control valve increases. The ground seal device for a steam turbine according to claim 3. 2. The steam turbine according to claim 1, wherein the ground leak steam leaked from the steam turbine to the ground portion is supplied to a ground seal passage downstream of the seal steam pressure control valve as seal steam of the ground portion. Gland seal device.

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