JPH09287408A - Erosion monitor for stationary blade of steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect erosion of the stationary blade of a steam turbine so as to beforehand prevent failure of a moving blade caused by excessive steam power by comparing and judging with a normal value found out by a calculating means, a real steam temperature and a stem regulating valve opening degree detected by each detector. SOLUTION: A device is provided with a steam turbine initial step moving blade outlet temperature detector 15, a steam regulating valve opening degree detector 14, and a power generator load detector 20. The steam turbine initial step moving blade outlet steam temperature corresponding to a load from those detector and the normal value of the steam regulating valve opening degree are found out by calculating means 23, 24. The normal value to be found out and real steam temperature to be detected, and the steam regulating valve opening degree are compared with each other, and it is judged by judging means 25, 26 whether or not they are within a constant allowable value on the basis of the normal value. In the case where the steam temperature and the steam regulating valve opening degree depart from the allowable value, alarm is informed by an alarm generating means 28. It is thus possible to properly monitor the erosion condition of a stationary blade at the time of operation, and it is also possible to prevent failure of the moving blade beforehand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for monitoring a steam turbine in a power plant or the like, and particularly to a state in which the stationary blades of the steam turbine are eroded by an oxide scale contained in steam generated from a boiler or the like. The present invention relates to a steam turbine vane erosion monitoring device that can be detected.

[0002]

2. Description of the Related Art A boiler tube in a power plant or a steam pipe connecting a steam turbine to a boiler is
During operation, scale such as high temperature iron oxide (Fe ₃ O ₄ ) is generated on the inner surface of the tube and the inner surface of the steam pipe. This scale of high-temperature iron oxide or the like generally grows to a thickness of about 10 to 20 μm per year, and if this scale becomes thick, some cause,
For example, if there is a temperature change due to a boiler stop, etc.
The iron oxide scale peels off, and when this scale restarts, it flows into the steam turbine together with steam, and can erode the stationary blades of the steam turbine, especially the first-stage stationary blades of the high-pressure turbine and the first-stage stationary blades of the medium-pressure turbine. is there.

This erosion increases the area of the portion of the stationary blades through which steam passes, increasing the input pressure of the moving blades and increasing the pressure difference across the moving blades. When a large amount of force is applied and the vane is significantly eroded, the blade may be damaged. When the high-pressure first-stage vane is eroded, the passage area of steam passing through the vane increases, and if the load of the generator is constant, the high-pressure first-stage vane inlet pressure decreases.

On the other hand, the inlet pressure of the steam turbine is generally 1
Because it is controlled from the boiler side so that 69kg / cm ² or 246 kg / cm ² such as the pressure of, the amount that is high initial-stage stator vane inlet pressure drops, the steam control valve provided in an inlet of the steam turbine It will be narrowed down.

Therefore, when the high-pressure first-stage stationary blade is corroded, the opening degree of the steam control valve is reduced. Further, when the high-pressure first stage stationary blade is eroded, the pressure difference at the inlet and outlet of the stationary blade cannot be effectively converted into velocity energy, so the outlet pressure of the stationary blade becomes high. Generally, the moving blade converts velocity energy in the stationary blade into rotation, but when the stationary blade outlet pressure, that is, the moving blade inlet pressure, the pressure difference in the moving blade increases, and an excessive force due to steam force is applied.

Further, the outlet pressure of the first-stage moving blade is almost proportional to the steam passage area of the next second-stage stationary blade, and the erosion degree of the second-stage stationary blade is much smaller than that of the first-stage stationary blade from the past experience. Under the condition that the machine output is constant, the outlet pressure of the first stage moving blade does not change much even if the high pressure first stage stationary blade is corroded with respect to the required amount of steam, and can be considered to be almost constant.

On the other hand, when the high-pressure first-stage stationary blades are eroded, the outlet steam of the high-pressure first-stage moving blades is throttled by the steam control valve due to the decrease of the inlet steam pressure of the high-pressure first-stage stationary blades. Since there is an isenthalpic change from the steam state at the inlet and the entropy increases from the steam state to the high-pressure first-stage stationary blade, the inlet steam temperature of the high-pressure first-stage moving blade becomes high when the high-pressure first-stage stationary blade is normal. Have.

[0008]

As described above, when the high-pressure first-stage stationary vanes are eroded, the high-pressure first-stage stationary vane inlet pressure decreases, so it is desirable to be able to detect this pressure.
No conventional steam turbine detects the pressure in this portion, and it is often structurally difficult even if a pressure gauge is added. In other words, in the case of small and medium-sized steam turbines, the steam control valve is often installed directly in the upper half or the lower half of the high-pressure outer casing, and the high-pressure first-stage vanes are used to improve plant performance such as plant partial load. For this reason, it has a nozzle box structure. Therefore, in order to detect the inlet steam pressure of the high-pressure first-stage stationary blade, it is necessary to penetrate the outer casing of the steam turbine.

Further, when the high-pressure first-stage stationary blade is eroded, the outlet steam pressure of the high-pressure first-stage stationary blade rises. However, since the gap between the outlet of the stationary blade and the inlet of the moving blade is only about several mm, the outlet Detecting vapor pressure is structurally difficult. Since the rotor blades generally rotate at 3000 revolutions or 3600 revolutions per minute, turbine shaft vibrations increase when the rotor blades are damaged, and the damage range is expanded. Therefore, if the blade is damaged, it is necessary to stop the plant immediately, and it takes a lot of money and time to restore the blade. Therefore, damage to the blade should be avoided as much as possible.

Conventionally, as a measure for preventing damage due to the iron oxide scale contained in the steam from the boiler, measures such as coating the surface of the stationary blade with a substance having high hardness have been taken, but the stationary blade has a certain extent. Although it is possible to delay the degree of erosion of iron, it cannot be completely prevented, and the vanes are also eroded by iron oxide scale over time.

Further, the iron oxide scale does not always flow in a constant amount, and there is also an unpredictable aspect. However, until now, there is no known monitoring device capable of appropriately detecting the erosion state of the stationary blade and taking an appropriate driving action before the blade is damaged, and such a monitoring device is strongly recommended. Was wanted.

The present invention has been made in view of the above circumstances, and detects that the stationary blades of the steam turbine are eroded by iron oxide scale or the like scattered from the boiler or the like during the operation of the steam turbine. It is an object of the present invention to provide a steam turbine stationary blade monitoring device which is optimal for preventing the moving blade from being damaged by an excessive steam force.

[0013]

To achieve the above object, the invention of claim 1 has a steam turbine for driving a generator and a steam control valve for controlling the amount of steam flowing into the steam turbine. A steam turbine facility is to be monitored, and a steam turbine first-stage rotor outlet temperature detector that detects the outlet steam temperature of the first-stage rotor blade of the steam turbine, and a steam control valve that detects the opening degree of the steam regulator valve A valve opening detector, a generator load detector that directly or indirectly detects the load of the generator, and a detection signal output from the generator load detector are input, and a steam turbine first stage corresponding to the load is input. Computation means for obtaining the normal values of the rotor blade outlet steam temperature and the steam control valve opening, and the normal value obtained by this calculation means and the actual steam temperature and steam control valve opening detected by the detector In comparison, both the steam temperature and the steam control valve opening are determined by the determination means that determines whether the steam temperature and the steam control valve opening are within a certain allowable value based on the normal value. Further, there is provided a steam turbine stationary blade erosion monitoring device, which is provided with an alarm generating means for issuing an alarm when the value deviates from the allowable value.

According to the steam turbine stationary blade erosion monitoring device of the present invention, it is detected that the steam temperature of the steam turbine first stage moving blade during operation is increased, and the opening degree of the steam control valve during operation is decreased. Is detected. In addition, the input steam temperature of the first-stage rotor and the opening of the steam control valve are compared with the planned value for any generator load or the operating data (normal value) when the stationary blade is normal, so the deviation from the normal value can be grasped. In addition, by inputting a value based on the requirement for the strength of the high-pressure first-stage moving blade as an allowable value, an alarm can be accurately issued and damage to the moving blade can be prevented.

According to the second aspect of the present invention, a steam turbine facility having a steam turbine for driving a generator and a steam control valve for controlling the amount of steam flowing into the steam turbine is to be monitored. A steam turbine inlet steam temperature detector that detects the inlet steam temperature of the steam turbine, a steam turbine inlet steam pressure detector that detects the inlet steam pressure of the steam turbine, and a temperature of the first stage rotor blade outlet steam of the steam turbine A steam turbine first stage rotor outlet steam temperature detector, and a steam turbine first stage rotor outlet steam pressure detector for detecting the outlet pressure of the first stage rotor blade of the steam turbine,
A steam control valve opening detector that detects the opening of the steam control valve, a generator load detector that directly or indirectly detects the load of the generator, and a detection signal output from this generator load detector Is input, a calculating means for obtaining a normal value of the internal efficiency of the steam turbine and a normal value of the steam control valve opening degree, the detection signals of the temperature and pressure detected by each of the detectors are input, and the steam turbine A turbine internal efficiency calculating means for calculating an actual internal efficiency, a normal value of the internal efficiency calculated by the calculating means and an actual internal efficiency calculated by the turbine internal efficiency calculating means, and the calculating means. The obtained normal value of the steam control valve opening is compared with the actual steam control valve opening detected by the detector, respectively, and the efficiency and the steam control valve opening are constant based on the normal value. And a warning generating means for issuing a warning when both the internal efficiency and the steam control valve opening deviate from the allowable values by the judging means. Provided is a steam turbine stationary blade erosion monitoring device.

According to the steam turbine stationary blade erosion monitoring device of the present invention, the internal efficiency of the first stage of the steam turbine during operation is calculated, and it is detected that the opening degree of the steam control valve during operation has decreased. . Also, in order to compare the calculated paragraph internal efficiency and steam control valve opening with the planned value for any generator load or the paragraph internal efficiency and steam control valve opening (normal value) when the vane is normal, the normal value Can be grasped and the value based on the strength of the high-pressure first-stage moving blade can be entered as the allowable value, so that an alarm can be issued when the erosion of the high-pressure first-stage stationary blade progresses and deviates from the allowable value. it can. Therefore, since measures such as plant stop can be taken before the moving blade is damaged, it is possible to prevent damage to the moving blade and prevent excessive damage expansion.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment (FIGS. 1 and 2) FIG. 1 shows an application example of a steam turbine stationary blade erosion monitoring device, which is a systematic diagram of the overall construction of a thermal power plant, and FIG. 2 is a steam turbine stationary blade. It is a systematic diagram which shows the principal part of an erosion monitoring apparatus.

First, the overall construction of a thermal power plant is shown in FIG.
It will be explained by.

As shown in FIG. 1, in the present embodiment, the steam generated in the boiler 1 is taken out through the steam pipe 2 and is controlled by the steam control valve 3 to a steam amount corresponding to the load of the generator. It flows into the turbine (high pressure turbine) 4. The steam that has worked in the high-pressure turbine 4 is reheated through the reheat steam pipe 5 and the boiler reheater 6, flows into the medium- and low-pressure turbine 7 for work, and is then returned to the condensate in the condenser 9. . The condensed water is supplied to the boiler 1 again via the water supply pump 11, the water supply heater 12, and the water supply pipe 13.

The high-pressure turbine 4 and the medium- and low-pressure turbine 7 are directly connected to the generator 8 and drive the generator 8 to generate electricity commensurate with the demand power of the power system. This thermal power plant is provided with a plant operation monitoring device A including an alarm function for monitoring plant operation and recording plant operation data.

The plant operation monitoring apparatus A includes a steam control valve 3
Steam control valve opening detector 14, which detects the opening of the high pressure turbine 4, high pressure first stage moving blade outlet temperature detector 15 and high pressure first stage moving blade outlet steam pressure detector 16 which detect the first stage moving blade outlet temperature and outlet pressure of the high pressure turbine 4. , Steam turbine inlet steam temperature detector 17 for detecting temperature and pressure of steam turbine inlet steam
And steam turbine inlet steam pressure detector 18, condenser 9
Condenser vacuum degree detector 19 and generator 8 for detecting the degree of vacuum
Generator load detector 20 for detecting the load of each, and each detection signal S1 output from each of these detectors 14 to 20
To a plant operation monitoring device main system 21 for inputting data necessary for plant operation based on S7 to S7. In the plant operation monitoring device main system 21, the input data is displayed and recorded, and an alarm is issued if necessary.

On the other hand, in the present embodiment, the steam turbine stationary blade erosion monitoring device B is provided. This steam turbine stationary blade erosion monitoring device B includes the above-mentioned detectors 14 to 20 and the operation detected by these detectors. Output signal S for data
1, S2, S3, S4, S5, S7 are provided by branching from the above plant operation monitoring device A and a steam turbine stationary blade erosion monitoring device main system 22.

FIG. 2 shows the system of the steam turbine vane erosion monitoring device B in detail.

As shown in FIG. 2, in the steam turbine stationary blade erosion monitoring device B, the steam turbine stationary blade erosion monitoring device main system 22a receives the operation data signal of the power plant from among the operation data signals.
From the generator load signal S7 output from the generator load signal detector 20, the high pressure first stage rotor outlet temperature signal S2 output from the high pressure first stage rotor outlet temperature detector 15, and the steam control valve opening detector 14 The steam control valve opening degree signal S1 that is output is input. The steam turbine vane erosion monitoring device main system 22a includes, as calculating means, a first function calculator 23 for calculating a relational value (normal value and allowable value) between the steam temperature and the generator load, and a steam control valve opening. And a second function calculator 24 that calculates a relational value (normal value and allowable value) between the degree and the generator load. In addition, the first and second determiners 2 serve as a determining unit that determines an actual input value based on the relational values obtained by the function calculators 23 and 24.
5, 26 are provided. Further, it is provided with an AND circuit 27 and an alarm device 28 connected to both the judging devices 25 and 26, and a recorder 29 for recording the detected value, the calculated value, the judgment result and the like.

In such a configuration, the generator load signal S7 is input to the first function calculator 23. The function calculator 23 calculates the steam temperature as a function of the generator load, and includes the steam temperature (normal value) when the high-pressure first-stage stationary blade is in a normal state in which it is not eroded and the high-pressure first-stage. The allowable value that represents the range where the rotor blade is not damaged is set,
The signal (permissible value signal) S8 indicating the normal value and the permissible value of the steam temperature according to the generator load during operation is sent to the first determiner 25.
Output to

The generator load signal S7 is also input to the second function calculator 24. This function calculator 24
Is a function that calculates the steam control valve opening as a function of the generator load, in which the steam control valve temperature (normal value) when the high pressure first stage stationary blade is not eroded and the high pressure first stage moving blade are The allowable value when eroded until just before damage is set, and the signal (allowable value signal) S9 indicating the normal value and the allowable value of the steam control valve opening degree according to the generator load during operation is set. 2 to the decision unit 26.

In the first judging device 25, the high temperature first stage rotor blade outlet temperature signal S2 during operation and the steam temperature allowable value signal S8 according to the generator load during operation are input, and it is determined whether or not it is within the allowable value. If the judgment is made and the allowable value is exceeded, A
The signal is output to the ND circuit 27.

Similarly, in the second judging device 26, the steam control valve opening signal S2 during operation and the allowable value signal S1 of the steam control valve opening according to the generator load during operation are input, It is determined whether or not it is within the allowable value, and if it exceeds the allowable value, a signal is output to the AND circuit 27. When both of these signals are output, the AND circuit 26 operates, an alarm command is output to the alarm device 28, and an alarm is issued. The signals S1, S2, S8 and S9 described above are recorded in the recorder 29.

According to this embodiment having such a structure, the fact that the first stage stationary blade is eroded by the scale during operation is
First, it is detected based on the outlet temperature of the first-stage rotor blade, and then by the change in the steam control valve opening.If both of these values exceed the allowable values, an alarm is issued to alert the operator. it can. Therefore, it is possible to take appropriate measures such as stopping and inspecting the plant before the moving blade is damaged. Further, since the recorder 29 can grasp the deviation from the normal value and the difference from the allowable value, it becomes possible to quantitatively grasp the progress of erosion before the alarm is issued.

Second Embodiment (FIGS. 1 and 3) FIG. 3 is a system diagram showing a second embodiment of the steam turbine stationary blade erosion monitoring device according to the present invention. The plant structure shown in FIG. It is incorporated similarly to the embodiment.

In the steam turbine stationary blade erosion monitoring device B2 according to this embodiment, the generator load signal S7 from the generator load detector 20 among the operation data signals of the power plant.
, A steam turbine inlet steam temperature signal S4 from the steam turbine inlet steam temperature detector 17, a steam pressure signal S5 at the steam turbine inlet from the steam turbine inlet steam pressure detector 18, and a high pressure first stage rotor blade outlet temperature detector 15 High pressure first stage moving blade outlet temperature signal S2 from the high pressure first stage moving blade outlet steam pressure detector 16
And the steam control valve opening signal S1 from the steam control valve opening detector 14 are the main system 22 of the steam turbine stationary blade erosion monitoring device.
b.

The main system 22b includes a turbine internal efficiency calculator 30, a first function calculator 31 for calculating the relational values of the turbine internal efficiency and the generator load, and a relational value of the steam control valve opening and the generator load. A second computing unit 32 for computing, first and second determining units 33, 34 for determining these values, A
An ND circuit 35, an alarm device 36, and a recorder 37 for detecting values, calculated values, determination results, etc. are provided.

The steam table data or calculation formula is previously input to the turbine internal efficiency calculator 30, and the input steam pressure and temperature signals S2, S3, S4.
The first stage internal efficiency of the turbine is calculated based on S5, and a signal (running internal efficiency signal) S10 representing the calculated first stage internal efficiency is output to the first determiner 33 and the recorder 37.

On the other hand, the normal value and the permissible value of the turbine internal efficiency, which is a function of the generator load, are input in advance to the first function calculator 31, and the generator load signal S7 during operation is inputted.
By inputting, the normal value and the allowable value of the turbine internal efficiency according to the generator load during operation are calculated. Then, the calculated allowable value of the turbine internal efficiency and the normal signal (allowable value signal) are sent to the first determiner 33 and the recorder 37.
S11 is output.

Further, the normal value and the allowable value of the steam control valve opening degree, which is a function of the generator load, are input in advance to the second function calculator 32, and the normal value and the allowable value of the steam control valve opening degree are inputted according to the generator load signal S7 such as the operation. Normal value and allowable value signal (allowable value signal) S12
Is output to the second determiner 34 and the recorder 37.

In the first judging device 33, the operating internal efficiency signal S10 outputted from the turbine internal efficiency calculating device 30 and the allowable value signal S11 outputted from the first function computing device 31.
The determination is made based on and, and when the internal efficiency is out of the allowable value, a signal is output to the AND circuit 35.

In the second judging device 35, the second function calculator 3
The allowable value signal S12 of the opening degree of the steam control valve 3 calculated in 2
Is determined based on the steam control valve opening signal S1 during operation and the steam control valve opening deviates from the allowable value.
A signal is output to the ND circuit 35. The AND circuit 35 operates when the signals from both the determiners 32 and 34 are input, and an alarm command is output to the alarm device 36 to issue an alarm.

According to the configuration of the second embodiment as described above,
The fact that the high-pressure first-stage stationary blade has been eroded by the scale can be reliably grasped based on the change in the turbine internal efficiency and the change in the steam control valve 3. In addition, when the value deviates from the allowable value, an alarm can be issued to notify the operator of the erosion of the stationary blades, and the recorder 37 can also notify the operator of the difference between the normal value and the allowable value. The same effect as that of the first embodiment is obtained.

Other Embodiments In each of the above embodiments, the generator load signal S7 is input, but the generator load signal S7 is not limited to the signal for directly detecting the load of the generator 8. However, it is assumed that it includes a detection signal of a value that can be considered to be substantially equivalent to the load, that is, a value that can indirectly represent the load, such as the main steam flow rate, the feed water flow rate, the high pressure first stage outlet pressure, or the high pressure exhaust pressure. Even if such a signal is adopted, the same operational effects as those of the above-described respective embodiments can be obtained. Further, the second embodiment can be applied to the monitoring of the intermediate-pressure turbine first stage stationary blade except for the opening degree of the steam control valve.

Further, although alarm devices 28 and 36 and recorders 29 and 37 are provided in the main systems 22a and 22b of the steam turbine stationary blade erosion monitoring device, these are also provided in the general plant operation monitoring device 21. Therefore, it is possible to use the alarm device of the plant operation monitoring device 20.

[0042]

As described in detail above, according to the present invention, it is possible to appropriately monitor the erosion condition of the steam turbine stationary blade during operation and prevent damage to the moving blade. And so on.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an entire thermal power plant for explaining an embodiment of the present invention.

FIG. 2 is a system diagram showing in detail the first embodiment of the present invention.

FIG. 3 is a system diagram showing a second embodiment of the present invention in detail.

[Explanation of symbols]

 1 Boiler 2 Steam Pipe 3 Steam Control Valve 4 Steam Turbine (High Pressure Turbine) 5 Reheat Steam Pipe 6 Boiler Reheater 7 Medium and Low Pressure Turbine 8 Generator 9 Condenser 11 Water Pump 12 Water Feed Heater 13 Water Supply Pipe 14 Steam Control Valve opening detector 15 High pressure first stage moving blade outlet temperature detector 16 High pressure first stage moving blade outlet steam pressure detector 17 Steam turbine inlet steam temperature detector 18 Steam turbine inlet steam pressure detector 19 Condenser vacuum degree detector 20 Power generation Machine load detector 21 Plant operation monitoring main system 22 Steam turbine stationary blade erosion monitoring main system 22a Steam turbine stationary blade erosion monitoring main system 22b Steam turbine stationary blade erosion monitoring main system 23 First function calculator 24 2 function calculator 25 1st judgment device 26 2nd judgment device 27 AND circuit 28 Alarm device 29 Recorder 30 Turbine internal effect Rate calculator 31 First function calculator 32 Second calculator 33 First judger 34 Second judger 35 AND circuit 36 Alarm device 37 Recorder

Claims (2)

[Claims] 1. A steam turbine facility having a steam turbine that drives a generator and a steam control valve that controls the amount of steam flowing into the steam turbine, the first stage operation of the steam turbine. Steam turbine first stage rotor blade outlet temperature detector that detects the outlet steam temperature of the blades, steam control valve opening detector that detects the opening of the steam control valve, and directly or indirectly detects the load of the generator A generator load detector, and a calculation means that receives the detection signal output from this generator load detector and obtains the normal values of the steam turbine first-stage rotor blade outlet steam temperature and the steam control valve opening corresponding to the load. , Comparing the normal value obtained by the calculation means with the actual steam temperature and steam control valve opening detected by the detector, and the steam temperature and steam control valve opening are based on the normal value. A determination means for determining whether or not it is within a predetermined allowable value, and an alarm generation means for issuing an alarm when both the steam temperature and the steam control valve opening deviate from the allowable value by the determination means. A steam turbine vane erosion monitoring device characterized by the above. 2. A steam turbine facility having a steam turbine that drives a generator and a steam control valve that controls the amount of steam flowing into the steam turbine, the inlet steam of the steam turbine being monitored. Steam turbine inlet steam temperature detector for detecting temperature, steam turbine inlet steam pressure detector for detecting inlet steam pressure of the steam turbine, and steam turbine first stage operation for detecting temperature of first stage moving blade outlet steam of the steam turbine Blade outlet steam temperature detector, steam turbine first stage rotor blade outlet steam pressure detector that detects the outlet pressure of the first stage moving blade of the steam turbine, and steam control valve opening degree detector that detects the degree of opening of the steam control valve And a generator load detector that directly or indirectly detects the load of the generator,
The detection signal output from the generator load detector is input, the calculating means for obtaining the normal value of the internal efficiency of the steam turbine and the normal value of the steam control valve opening, and the temperature detected by each detector and A turbine internal efficiency calculating means for calculating the actual internal efficiency of the steam turbine when a pressure detection signal is input, a normal value of the internal efficiency obtained by the calculating means, and an actual value calculated by the turbine internal efficiency calculating means. The internal efficiency of the steam control valve and the normal value of the steam control valve opening obtained by the calculation means and the actual steam control valve opening detected by the detector are compared to determine the efficiency and the steam control valve. Both the internal efficiency and the steam control valve opening deviate from the permissible value by the judgment means for judging whether or not the valve opening is within a certain permissible value based on the normal value. The steam turbine stationary blade erosion monitoring apparatus characterized by comprising a warning issuing means for issuing an alarm when.