JPS62199902A - Pressure regulator for steam turbine gland steam sealing system - Google Patents

Abstract

PURPOSE:To aim at enhancing the controllability during transient response, by obtaining an opening degree request indicating signal in a pressure regulator from a turbine output, thereby driving a three-way valve. CONSTITUTION:The output of a high pressure turbine 4 is detected by a first step blade outlet pressure detector 52 in the high pressure turbine, and is inputted to a function generator 53 for an opening degree request indication. The output signal of the function generator 53 is inputted to a driving device 55 via a proportional arithmetic circuit 54 and a signal generator 62. When a load is cut-off, a control signal based on the pressure detector 52 in the turbine first step blade is preceedingly inputted to the driving device 55 thereby a three- way valve 18 interlocked with a gland steam sealing adjusting device 17 is adjusted. With this arrangement, it is possible to keep the pressure at a constant valve without delaying in motions during transient response.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (INDUSTRIAL APPLICATION) The present invention relates to a method for regulating pressure in a Grantsdam seal system in a steam turbine.

(Prior Art) Steam seals are often used as a method for sealing the gland of a steam turbine in a steam power station.

FIG. 3 shows a typical system, where the dashed line shows the main steam cycle and the solid line shows the steam turbine grand steam seal system. In the figure, hot air from a boiler 1 passes through a steam valve 2.3 and enters a high-pressure turbine 4.
After working here, it is reheated in the reheater 5, and the steam valve 6
, 7, enters an intermediate pressure turbine 8, where it performs work, and then flows into a condenser 11 via a low pressure turbine 9.10e. Condensate from the condenser 11 is fed to several stages of low-pressure feed water heaters 12a.
, via the high-pressure feed water heater 12b and the water feed pump 13,
It is heated again in the boiler to form high-temperature, n-pressure steam and a reheat regeneration cycle.

On the other hand, the gland portion of the steam turbine rotor 14 is sealed by a steam sealing method shown by a solid line. Details of this sealing method are shown below.

The through-hole part of the turbine casing wall (not shown) of the steam turbine row 914 is provided with a structure to prevent high-pressure and high-temperature steam inside the casing from leaking into the turbine, or to prevent air from entering the low-pressure turbine from the popular side. A labyrinth-style backing is provided. The backing provides a continuous throttling effect on the steam or air flowing along the rotating steam turbine rotor 14 to minimize leakage.

In the middle of this labyrinth backing, there is a steam seal header 15 (where the header pressure is kept constant).
Hereinafter, it will be referred to as 5S11. ) and a connection chamber with the ground steam condenser 16, which is always maintained below atmospheric pressure.

During constant load operation of the steam turbine, these components cause the hot air pressure of the steam inside the turbine casing in the gland section of the high/intermediate pressure turbine 4.8 to reach SSI + line pressure (
About 0.3! Since it is higher than l / ci (about +),
It flows into the SSI+ line 15 connection room through the labyrinth backing.

In addition, the steam in the SSH line 15 connection chamber passes through the labyrinth backing located on the outside (atmospheric side), and passes through the grand steam condenser 16 connection chamber (the constant pressure is -100 #II in the water column).
(negative pressure of about I+). Grand steam condenser 16
Since the connection chamber has a negative pressure, air from the atmosphere side will also flow in in addition to the steam from the 5SII line. Such a configuration prevents swallow air from leaking into the atmosphere from the high/medium pressure turbine 4.8 during constant load.

On the other hand, in the steam turbine rotor gland parts of the low pressure turbines 9 and 1o, and in the turbine gland parts at the time of starting the high and intermediate pressure turbines, unlike the high and intermediate pressure turbines 4 and 8 at constant load, the casing internal pressure is restored. Because it is connected to the water dispenser 11, there will be negative pressure, so 33+1 line 1
The steam from the 5 chambers flows into the casing of the high/intermediate pressure turbine 4.8 or the low pressure turbine 9 through the connection chamber J: Libirin Packing, while on the other hand, the steam flows into the casing of the high/intermediate pressure turbine 4.8 or the low pressure turbine 9. Because it also flows into the 16 connection room,
Air intrusion from the popular side into the high/intermediate pressure turbine 4.8 or the low pressure turbine 9 is completely prevented.

The broken line in Fig. 4 indicates the steam turbine output (L) and the leakage steam ffi from the turbine gland to the 5511 line 15.
(Ql.J, that is, the difference between the amount of steam leaking from the high- and intermediate-pressure turbines and the amount of steam flowing into the low-pressure turbine). A small amount of steam leaks from the gland of the high/intermediate pressure turbine 4.8 to the 5SII line 15, and also flows into the steam casing of the 3311 line 15 through the gland of the low pressure turbine 9, so the amount of leaked steam is negative. It shows the value. On the other hand, above 50% output, the leakage steam from the high and intermediate pressure turbines 4 and 8 tends to gradually increase, while the amount of steam flowing into the low pressure turbine casing varies depending on the load.
Since it remains constant, it shows a positive value.

It is necessary to keep the ground backing 33 + 1 line 15 connection chamber constant (approximately 0.3!l/Cdg) against changes in leakage steam due to the turbine output.

That is, when the turbine output is below 50% d3, the steam B1 shown by the solid line Q2 in FIG. 4 must be supplied from another system to the 3311 line 15, and the turbine output 5
At 0% or higher, it is necessary to release excess steam in the SSH line 15 to other systems.

A Grantsdam seal adjustment device 17 is provided as a device for supplying steam to the SSH line 15 or releasing surplus steam to keep the steam pressure in the SSI+ line 15 constant. A three-way switching valve 18 that is linked to a gland steam seal adjustment device is installed in the.

Generally, four steam lines (not shown in FIG. 3) are connected to the ground steam seal adjusting device 17. These four systems are a connection line 20 with the SSH line 15, a connection line 21 with the main steam piping, a connection line 23 with the auxiliary steam header 22 connected to the low temperature reheat steam line, and a connection line 23 with the three-way switching valve 18. This is the connection line 24.

Main steam connection line 21, auxiliary hot air header connection line 2
Both lines 31.1 and 31.1 are used to supply steam to the grand steam seal adjusting device 17, and the three-way switching valve connection line 24 is used to release excess steam.

In addition, surplus steam from this three-way switching valve 18 is transferred to the condenser 1
1 and a connection line 26 to the feed water heater 12.

The control system diagram of the Grantsdam seal adjusting device Q17J3J and three-way ti7J switching valve 18 having the above-mentioned connection system is shown in FIG. 5, the Grantsdam seal regulating device valve m1 degree characteristic diagram is shown in FIG. 6, and the control block diagram are shown in Figure 7.

In Fig. 5, the steam pressure of the SSI+ line PSS11
is inputted via the waterbot 19 to the bellows 17a of the gland steam seal adjusting device. This bellow 17
8 is transmitted to the pilot valve 17c via the lever 17b, and depending on the position of the pilot valve 17C, the control oil 17d is sent into the upper or lower chamber of the oil cylinder screw 17e, causing the oil cylinder piston rod 17f to move up and down. Don't move in any direction. This movement is transmitted directly or via the cam 17j' to the high pressure steam valve 170, auxiliary steam valve 17h, and relief valve 171, opening and closing these. Therefore, the steam pressure P of 5511 line 15 and the pressure setting value P (approximately 0.3SSI
A deviation of I o 3311Kg/crhJ) moves the oil cylinder piston 17e.

The opening characteristics of this oil cylinder piston 17e and each valve are shown in FIG.

For example, when the turbine output is about 50% from when the turbine is started, the pressure P in the 3311 line 15 as shown in FIG.
SSI+ tends to decrease with respect to the pressure setting value because the leakage steam from the high/intermediate pressure turbine 4.8 is smaller than the steam flowing into the low pressure turbine 9.

As a correction for this, steam supply from the high pressure steam line 21 and the auxiliary steam header 23 is required, but as the turbine output increases, the S
Since steam leakage to the SI+ line increases, the supplied steam tends to gradually decrease.

Conversely, at rated output, the difference between the leakage air from the high/intermediate pressure turbine 4.8 and the steam flowing into the low pressure turbine 9 is 8.
Since there is a tendency to increase the pressure in the 3115-in 15, the high-pressure steam valve 17i and the auxiliary steam valve 17h are fully opened, and excess steam is discharged from the 5S11 line 15. Lever 17 has one dowel bot 171, piston 17
Both of them are feedback mechanisms, which are used to balance the valve 17G to the pylon 1, that is, to stop the oil cylinder piston 17e at a balanced position with respect to pressure deviation.

FIG. 7 illustrates a control block diagram of the gland steam seal adjustment device 17 and the three-way switching valve 18, in which surplus air from the gland steam seal adjustment Pid relief valve 171 passes through the three-way switching valve 18a or 18b. It is discharged to either the condensate 2g11 or the feedwater heating "a12." This valve water control operation is performed by directing excess steam in the 3311 line 15 to the three-way switching valve 18b in order to improve the blunt thermal efficiency in the turbine rated output operating state. Water supply heater 1
However, in the event of an abnormality, the line 26 to the feedwater heater 12 is connected to the low-pressure turbine bleed line 27, so there is a possibility that it will flow backwards and cause the turbine blades to become damaged. To prevent this, the feed water heater side valve 18b of the three-way switching valve 18 is closed, while the condenser side valve 18a is closed.
is fully opened to allow excess steam to escape to the condenser.

The switching operation of the valve 18a or 18b of the three-way switching valve 18 is performed by an air valve 28 installed in the gland steam seal adjustment device and an electromagnetic valve connected to the three-way switching valve 18, as shown in FIGS. 5 and 7. This is implemented by a valve 29. In either case, when the air pressure 30 to the air bellow, which is the driving device for the three-way switching valve 18, is cut off, the condenser side valve 18a
While asking all questions, fully open the feed water heater side valve 18b,
This will result in switching to the condenser side 25.

Note that the air pressure 30 is cut off when the natural air supply bypass valves 31 and 32 (to prevent erroneous operation during operation) signal is sent to the feed water heater 12, as shown in Fig. 6 J3 and Fig. 7. When the line temperature high signal 33 and manual signal 34 are input, the solenoid valve 29 is in a non-excited state, the valve 18a is closed, the valve 18b is fully opened, and excess steam is released to the condenser 11. .

Similarly, the steam supply valve 17 of the gland steam seal device
1 or 17h is open (when the steam supply valve may become ticked), the air supply from the air valve 28 to the three-way switching valve 18 is cut off, and the air is discharged to the condenser side 25.

(Problems to be Solved by the Invention) The prior art with the above-mentioned components and operations has the following problems and improvements.

(1) The pressure detection mechanism of Grantsdam seal adjustment device d directly detects the SSH line pressure, and the 5811 line time constant is proportional to the piping volume, so it is shown at time T1 in Figure 8. Load i! ! If a sudden load change occurs such as a power outage, close the hot air supply valves 17G and 17h.
If the same speed cannot be followed and the 5S11 line pressure is set below the specified pressure, and the followability is extremely poor, there is a risk that air will enter the steam turbine from the atmosphere.

(2) Since the driving force of the three-way switching valve is air, there is a problem in the responsiveness after the switching signal is input. For example, if a load shedding occurs at indicated time T1 in FIG.
The three-way switching valve 18a is switched from fully open to fully open, and the three-way switching valve 18b is switched from fully open to fully open, but this cannot be followed and the operation is actually completed at time T3. . This delay in control operation sometimes causes high-temperature steam to flow backward into the low-pressure turbine from the feedwater heater side, leaving a risk that the blades may be biased by 10 degrees.

(3) The gland steam seal adjustment device is a hydraulic mechanism, while the three-way switching valve is pneumatically operated, so in order to secure the driving source for these, it is necessary to install various piping such as oil pipes and air pipes. It is hoped that this will become a reality.

(4) Control oil, which is the driving force source for the grand steam seal adjustment device, is supplied by an electric auxiliary oil pump before starting the turbine, and during normal turbine operation, it is supplied by the main oil pump directly connected to the turbine rotor. However, the only use of the electric auxiliary oil pump before startup is as a gland steam seal adjustment device. For this reason, if the gland steam seal adjustment device could be driven using a different method, there would be no need to rotate the electric auxiliary oil pump before starting it, which would greatly reduce the power required for auxiliary equipment. was impossible.

(5) The switching of the three-way switching valve is ON-OFF operation (either the feed water heater side or the condenser side). If it had a function that enabled mid-way opening control, it would be possible to supply steam to the feed water heater side even during low load times, thereby improving plant efficiency, but this is not possible with conventional equipment. It was possible.

The present invention addresses the above-mentioned points of conventional gland steam pressure regulators and three-way switching valves, namely, improves controllability during transient response, simplifies the driving power source, and auxiliary power when starting the turbine. It is an object of the present invention to provide a steam turbine gland steam seal system pressure regulating device that enables reduction and improvement of blunt efficiency.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, the present invention provides an electric grand steam pressure regulator Y, a three-way switching valve, an electric grand steam pressure regulator opening request number I, and a function generator. 331 for controlling the turbine output, which is also an input signal to the function generator, the SSH line pressure detection device and pressure setting device for correcting the function generator output signal, and the electric three-way switching valve.
1-line temperature detector, which uses the turbine output as an input signal, feedwater heater inlet temperature prediction function generator, feedwater heater inlet temperature detection relay that controls the feedwater heater protection interlock, and ground steam pressure regulator. Consists of a detection circuit.

FIG. 1 shows a control block for the gland steam pressure regulator and three-way switching valve of the present invention having the above-described configuration. Note that the same components as in the prior art are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, the control blocks of the grand steam pressure regulating device include an SSH line pressure detection 1155Q, a line pressure setting value (pref) 3311 51, a high pressure turbine first stage blade outlet pressure detector 52 that detects the steam turbine output,
Grand steam pressure regulator opening request instruction function generator 5
3, a proportional calculation circuit 54, and a driving device 55 for a ground steam pressure regulating device to which an opening request signal is input. The drive device 55 also includes a control interlude 55b1 for controlling the motor 55a, an opening detector 55c,
The driving gears are composed of 55 dJ.

On the other hand, the three-way switching valve control block is connected to the 5S11 line for temperature detection 2!1i60, a function generator 61 for the predicted value (set value) of the extraction line temperature to the feed water heater 12 that uses the high pressure turbine first stage blade outlet pressure as an input signal, and a proportional The arithmetic circuit 54 inputs the Grand Sdam seal adjustment device opening degree instruction signal;
When the signal value is at a low level, the signal Σ generates a signal that forcibly switches the three-way switching valve 18 to the condenser side.
) generator 62, the temperature detection relay 33, the deviation signal between the signal from the temperature expected value (set value) function generator 61 and the SS++ line temperature detector 60, and the signal from the signal generator 62. It is comprised of a low value priority circuit 63 that gives priority to low values among signal levels.

(for production) Next, the relationship and operation of each of these components will be explained.

The pressure control method for the 3311 line in the prior art is 38
This was done by moving the oil cylinder screw, which is the drive device, depending on the deviation between the 11 line pressure set value and the actual pressure. determined a priori as a function of the stage vane specific opening pressure.

The turbine 182nd blade specific pressure has a characteristic that increases in proportion to the turbine output, and also has a characteristic that it increases in proportion to the turbine output.
Steam supply from high/medium pressure turbine to 311 line 11
1 (The amount of steam flowing into the low-pressure turbine from the +3 and SSH lines has the characteristics shown in FIG. 4, as described in the prior art described above.

Therefore, the opening degree of the grant boom seal adjustment device 17 can be determined in advance once the turbine output is determined, and this function is performed by the function generator 53.

3311 line pressure detector 50 and pressure set value pref
This is to correct this advance opening determination value, and if the actual pressure of the SSI+ line is higher than the pressure setting value,
The deviation signal is added to the advance opening signal U, and the relief valve 17i is operated in the opening direction, thereby acting to lower the actual pressure of the SS++ line.

Conversely, if the actual pressure of the SSI+ line is low, release valve 1
7i and fully open the auxiliary steam supply valve 17h and high pressure steam supply valve 17q, the pressure horn is restored to the 5S11 line.

The power of the grand steam seal adjustment device 55! FJJ Sosho uses the opening command signal 55e as an input signal, and the pulse signal generator 55b1 receives this pulse signal to drive the gear worm etc. The drive motor 55a1 outputs the output signal of this drive motor, that is, the ground steam seal adjustment device 55. It is composed of an opening degree detector 55c that detects the position,
An actual opening signal 55f from the opening detector 55c forms a feedback circuit with respect to the opening command signal D55e, and the deviation thereof serves as an input signal to the pulse signal generator 55b.

On the other hand, the opening degree command signal 55a of the three-way switching valve 18 is output from the extraction line temperature expected value generator 61 which receives the first stage blade outlet pressure 52 of the turbine as an input.

As mentioned above, the first stage outlet pressure 52 of the turbine represents the output of the turbine, but once the output is determined, the low pressure turbine bleed line temperature related to the turbine output can be easily determined based on the plant heat 81. This can be expected.

Temperature expected value from function generator 61, that is, temperature set value 6
1a is compared with the temperature signal from the SSH line temperature detector 60, and provides the deviation signal to the iJJ inlet 55 of the three-way switching valve 18. This drive device has the same functions as the drive device of the above-mentioned Grantsdam seal adjustment device, so it is designated by the same reference numerals.

The low value priority circuit 63 is activated by a temperature deviation signal when the bleed air line temperature is abnormal or when the opening request signal to the Grant Sdam seal adjustment device reaches a level that causes the three-way switching valve 18 to completely escape to the condenser side. It controls the three-way switching valve 18 by giving priority to the opening request signal that is formed, and in both cases, C also controls the condenser side valve 18a of the three-way switching valve 18.
is fully opened, and the feed water heater side valve 18b is closed.

(Example) The dash-dash line in FIG. 2 shows the behavior of each element in J3 during turbine operation when the Grantsdam seal adjusting device according to the present invention, a'3 and the three-way switching valve are used. The behavior of opening in the second direction is as explained in Figure 8, and
In the figure, it is indicated by a solid line).

In a process where the increase in output is relatively slow at the time of turbine startup, it is necessary to adjust the grant seal.
The behavior of the pressure (P'') in the 3311 line, the high pressure steam valve 17Q1, the high pressure hot air auxiliary valve 17h, and the rice relief valve 17i is also the same as in the prior art.

However, the valves 18a and 18b of the three-way switching valve 18 are at time T. It is already in the control 211 state. For this reason, at time T1, in the conventional technology, the condenser side valve 18a first enters a fully open operation, and at time T2, it is fully opened, and the feed water heater side valve 18b is fully opened, whereas according to the present invention, At time T1, J3, the condenser valve 18a is already close to fully open, and the feed water heating side valve 18b is already close to fully open. Therefore, during the period from time T1 to 12, surplus steam can be supplied to the feed water heater side, which leads to Plan 1 - improvement in thermal efficiency.

This switching valve mid-opening control is also established when the high pressure steam bypass valve 31 and the auxiliary steam bypass valve 32 shown in FIG. 7 are opened. In the prior art, the three-way switching valve 18 was set to fully open on the condenser side, but in the present invention, since the actual temperature is controlled with respect to the reference temperature, these valves are always opened on the feed water heater side. To ensure the maximum allowable amount of steam in the drain, determine its opening and improve the blunt thermal efficiency.

Furthermore, when a load shedding occurs at time T3, in the conventional technology, the control operation is started at time T, and at time T5, because there is a delay in the pressure detection device and the gland steam seal adjustment device. However, during this time, the 3311 line pressure PSSI+ cannot be maintained at a constant value, and the F force will be considerably low, and it will take a long time to settle to 1°. becomes.

In terms of static characteristics, the three-way switching valve should start the switching operation at time T6, but since it is an air-operated type, there is a delay in the control operation, and the switching operation does not start until time TI. Between times 16 and 17, there remains a possibility that high-temperature steam may flow into the feed water heater side.

On the other hand, according to the present invention, the valve position control signal from the turbine first stage blade outflow pressure detector is input in advance to the gland steam seal adjustment device at the time of load cutoff, so that the control operation is in the closing direction (relief valve fully open, high pressure steam valve and auxiliary S air valve fully open) without any delay.
Start the action.

Therefore, the pressure drop in the SSI+ line is small, and it is possible to maintain the pressure at a nearly constant value.

Further, the switching operation of the three-way switching valve 18 is also performed electrically,
Similar to the ground steam seal adjustment device, it reduces the absolute temperature value associated with a sudden drop in the turbine first stage outlet pressure, and also forcibly switches from the feed water heater side to the condenser side, so there is no near-operation, and 'R This is a desirable result in terms of steam protection.

In addition to this, in the system 7 of the present invention, the drive method is changed from hydraulic or air drive to electric.
Oil pipes and air pipes can be eliminated, making it possible to simplify equipment and reduce auxiliary power when starting the turbine.

〔Effect of the invention〕

As described above, according to the present invention, problems and improvements in the conventional technology can be solved, and a simple device has excellent responsiveness, and moreover, it is possible to improve efficiency during plant operation and reduce auxiliary machine power. It becomes possible to provide a steam turbine grand steam seal system pressure regulating device.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the control system of the present invention, Fig. 2 is an explanatory diagram of the behavior of the gland steam seal adjusting device and three-way switching valve according to the present invention and the prior art, and Fig. 3 is a typical steam turbine gland. Steam seal system diagram; Figure 4 is a characteristic diagram showing the relationship between turbine output, steam supply to the SSI+ line, and release amount; Figure 5 is a conventional grand steam seal adjustment device and three-way switching valve control DI+
System diagram, Fig. 6 is a valve opening characteristic diagram of the gland steam seal device, Fig. 7 is a control block diagram of the gland steam seal adjusting device and three-way switching valve according to the conventional technology, and Fig. 18 is a diagram of the gland according to the conventional technology. It is a behavior explanatory diagram of a steam seal adjustment device and a three-way switching valve. 1... Boiler, 2.3, 6.7... Main steam valve, 4
... High pressure turbine, 5... Reheater, 8... Intermediate pressure turbine, 9.10... Low pressure turbine, 11... Condenser, 12... Feed water heater, 13...・Water pump, 1
4... Steam turbine rotor, 15... Steam seal header (SS11'), 16... Grand steam condenser, 17... Grand steam seal adjustment device, 18... Three-way switching valve, 19... ...Water spot, 20...5S11 connection line, 21...Main steam pipe connection line, 22...Auxiliary hot air header, 23゛...
・Auxiliary steam header connection line, 24...three-way #JJ
Replacement valve connection line, 25...Condenser connection line, 26.
... Feed water heater connection line, 27 ... Low pressure turbine extraction line, 28 ... Air valve, 29 ... Solenoid valve, 30
...Air pressure, 31.32...Bypass valve, 33...
・Temperature switch, 50... 3311 line pressure detector, 51... Pressure setting device, 52... Turbine first stage output pressure detector, 53... Function generator, 54... Proportional operation p circuit, 55... Drive device, 60... SSM line depletion detector, 61... Bleed air line temperature expected value function generator, 62... Shinyuki generator, 63... Low value priority circuit. Applicant's agent Mr. Yu Sato l Usjin 2 Figure 6 '' Figure 7

Claims (1)

[Scope of Claims] 1. A pressure regulator that constantly controls the steam pressure of a steam turbine grand steam seal system, comprising: a function generator that uses a turbine output as an input signal and uses a pressure regulator opening request instruction as an output signal; an opening request instruction signal correction function generator that corrects the opening request instruction signal using a deviation signal between the ground steam seal system actual pressure and the pressure setting value; and an opening request signal correction function generator that inputs the opening request instruction signal to operate a pressure regulator. a function generator that takes the turbine output as an input signal and calculates the expected temperature value of the low-pressure turbine bleed air line and uses it as a temperature set value; and an output signal of the grand steam seal system steam temperature detector and the temperature A steam turbine grand steam seal characterized by having an electric drive device that generates a temperature deviation signal based on a set value and operates a three-way switching valve communicating with a steam system of the pressure regulating device by giving an opening request signal. System pressure regulator. 2 In the three-way switching valve, a low value priority circuit is provided in the opening request instruction signal path, and the deviation signal between the expected temperature of the low pressure turbine bleed air line and the steam seal system temperature is used as the low pressure turbine bleed line temperature detection relay signal and the ground steam seal. Claim 1: A three-way switching valve opening request signal that is influenced by a pressure regulator opening request signal is input, and the three-way switching valve is connected and controlled by a low value signal.
Steam turbine gland steam seal system pressure regulating device as described in .