JPH02125903A - Governing valve vibration diagnostic device - Google Patents

Abstract

PURPOSE:To improve operational safety by continuously diagnosing the vibration of the valve stem portion of a governing valve and also calculating valve stem operating stress, and in case that this stress is in a dangerous area, and operat ing a warning means and also limiting the operation. CONSTITUTION:A valve vibration measuring unit 3, is provided, which continu ously measures the vibration of the valve stem 16 of a governing valve 1 having a main valve 1a opened and closed by an oil cylinder portion 1e via a lever portion 1f and valve stem vibration stress value applying to the valve stem 1b is calculated according to the measured data thereby. A valve opening calcula tion unit 4, to which a signal is output from a load requiring signal unit 5, and which calculates valve opening according to the load requiring value of a steam turbine, is provided and static stress applied to the valve stem 1b is calculated in a valve stem static stress calculation unit 6 through the valve opening. The fatigue strength of the valve stem 1b is calculated in a fatigue strength calculation unit 7 according to the calculated valve stem vibration stress calculation value and the static stress calculation value and when it is judged in a judgement unit that the strength is in a dangerous area, a warning is announced with a speaker 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a steam control valve for a steam turbine, and more particularly to an apparatus for diagnosing abnormal vibration of a valve stem of a steam valve.

(Prior Art) Steam turbines are generally equipped with a plurality of steam control valves on the inlet side to control the rotational speed at startup and the turbine output during normal operation, that is, the amount of steam flowing into the turbine. ing. These steam control valves are used in a high-temperature, high-pressure steam environment generated from a boiler superheater or the like, and are operated under severe conditions in order to throttle the steam flow rate.

On the other hand, as for the opening method of the steam control valve, there is a simultaneous opening method for all valves, which aims to alleviate the thermal stress generated by creating a uniform temperature distribution in the circumferential direction of the first stage nozzle of the high-pressure turbine, or a method that emphasizes turbine efficiency. A typical method is a multi-atomization method in which one valve is opened one by one (for example, 4 atomizations in the case of 4 valves), and depending on the operating method, a 3-atomization method (time-opening method between 1 and 2 valves) is an intermediate method. , 2-atomization (time-opening between valves 1, 2, and 3) system is adopted.

Now, the steam control valve is a ball-type valve that minimizes pressure loss when the valve is fully open in order to increase turbine efficiency.One of the characteristics of this ball-type valve is that when the valve is closed, The vibration of the valve may increase.

Based on past experience or experimental data, it has been confirmed that this valve vibration occurs at a constant pressure ratio (valve riff 1-).An example of this is shown in Figure 6. Valve opening degree (valve lift/valve seat diameter) 0.05~
Valve vibration is high near 0.07. This is presumed to be because when the shock waves generated at the minimum passage area, that is, the throat section of the steam passage section formed by the valve seat and the valve become unstable, they cause turbulence in the flow.

Depending on the operation of the steam turbine, operation may continue at this valve opening, and the high vibration may accelerate wear on various parts, or in severe cases, the valve stem may break due to fatigue, which may interfere with steam turbine control. leading to unforeseen circumstances. However, since load requests are prioritized in the operation of a steam turbine, it has been considered unavoidable to stop operation even if the steam control valve vibration generation region is recognized in advance.

On the other hand, in recent years, due to the increase in the operating rate of nuclear power plants and the increase in occupancy rate, general thermal power plants are operated for load adjustment, and steam control valves are used to comply with the central power supply directive for operational loads. Conditions are becoming increasingly harsh. For example, in the case of a 4-atomization valve opening method,
As is clear from the relationship between load and valve stem vibration value in Figure 7,
Valve stem vibration values are high in the vibration generation range of each control valve, and vibration of control valves is observed in all load ranges, making it difficult to impose operational restrictions.

In order to reduce the failure rate due to vibration of the steam control valve under these constraint conditions, the steam control valve is disassembled during periodic shutdown inspections of the steam turbine, and the damage and wear conditions of the valve stem etc. are ascertained. We carry out damage inspections, gap inspections of sliding parts, and parts replacements, or measure the vibration value of the steam control valve at startup after periodic inspections to confirm whether it is within the control standard value. It is.

(Problem to be solved by the invention) However, these current management methods are only carried out during regular inspections and are not continuous methods, so for example, when starting up after replacing sliding parts, the vibration value of the valve Even if the vibration value is low, if the operating method is harsh as shown in Figure 7, the valve stem and other sliding parts will wear out, and this wear will generally cause the vibration value to rise again. Continuous vibration monitoring was desired because the vibration was different from the initial state.

In addition, even if the vibration value of the steam control valve exceeds the control standard value, there are times when it is forced to operate in a high vibration range due to power supply, and in this case, the valve stem may break. It is necessary to judge whether the vibration is such as to lead to an unexpected situation, but there remains the problem that there is no means for making this judgment.

Furthermore, based on the current operational status of the steam control valve, wear parts,
If preventive maintenance technology is introduced that estimates damaged parts and prepares for unexpected situations, or plans in advance to replace or inspect parts during the next periodic inspection, the reliability and operation of the steam control valve will improve. The rate is expected to be several steps higher than the current rate.

- To - This invention was made in view of the circumstances mentioned in -1-, and its purpose is to reduce valve vibration (particularly the valve stem portion) of a steam control valve during operation.
By continuously monitoring, damage and wear conditions of steam valve stems or sliding parts can be predicted, and if necessary,
To provide a steam control valve vibration diagnostic device that can improve the reliability or operating rate of a steam control valve by imposing operational restrictions and generating messages that enable planned preventive maintenance. be.

[Structure of the invention]

(Means for Solving Problem a) The vibration diagnostic device for a steam control valve according to the present invention includes a valve stem vibration measurement unit that continuously measures the vibration of the valve stem of the steam control valve during operation; A calculation unit that calculates the valve stem vibration stress value acting on the valve stem from the measurement data and the assembled state value of the steam control valve, and a calculation unit that calculates the valve opening degree from the load request value to the steam turbine.
A calculation unit calculates the static stress due to steam unbalance force and valve stem bending force acting on the valve stem from the valve opening degree, and calculates the fatigue strength of the valve stem from the calculated value of vibration stress and static stress of the valve stem. The present invention is characterized by comprising a judgment unit that judges whether the detected value is in the safe range or in the dangerous range.

(Function) According to the steam regulating valve vibration diagnosis device of the present invention, it is possible to continuously monitor the vibration of the valve stem of the steam regulating valve.
If the vibration is in a dangerous range, the system not only notifies the operator immediately but also imposes operational restrictions, allowing for safer operation.

Furthermore, if operation in the hazardous area continues, we will estimate the remaining life of the valve stem, perform inspections during periodic inspections, etc., in response to operator requests.
Planned maintenance becomes possible by outputting disassembly instructions and the need for new parts.

In addition, since the valve stem fatigue strength calculation of this diagnostic device is performed based on the latest information such as main steam pressure correction and valve assembly information, highly reliable information regarding safety can be obtained.

(Example) An example of the present invention will be described using FIGS. 1 to 4.

In Fig. 1, 1 shows a structural diagram of the entire steam control valve that is the object of the present invention, Ia is the main valve, lb is the valve stem, lc is the valve stem bushing, 1d is the crosshead, and le is the oil cylinder. 1f is a part of the lever. Vibration sensor 2 is valve stem 1b
It is installed on the crosshead ld which is connected to the valve stem 1b at the upper end of the valve, and measures the vibration value of the valve stem 1b during operation.

When the vibration diagnosis device according to the present invention starts diagnosis during operation, the valve stem vibration measurement section 3 receives vibration values (amplitude, acceleration, etc.) from the vibration sensor 2, while the valve opening calculation section 4 Then, according to the load request signal unit 5 required for the steam turbine, if the steam control valve 1 has four valves, the valve opening degree Q,, f
fi,, ff13. n, are calculated respectively. Figure 2 shows an example of this calculation method, but in this example, the valve opening method is sequential and the vibration of the valve stem of the fourth valve is diagnosed (based on the output signal of the valve opening calculation section). explain.

The valve stem static stress calculation unit 6 calculates the valve opening Q4 and the valve cylinder pressure P during operation from the valve opening calculation unit 4.

are input, and using these values as parameters, the static stress σ acting on the valve stem is calculated.

The details of the static stress σ acting on the valve stem will be explained in FIG.

This static stress σ is the stress σ due to the steam imbalance that acts on the main valve 1a (that is, the valve stem connected thereto) due to the steam pressure difference before and after the main valve 1a. and main valve 1
The bending stress σ8 acts on the valve stem ib from the lever part If when the valve a overcomes the steam unbalance force and opens the valve. Figure 4 shows the valve stem stress σ□ and valve stem bending stress σ8 due to steam imbalance, with the horizontal axis as the valve lift Q and the vertical axis as the static stress σ1 of the valve stem. Valve lift Q4 is valve cylinder pressure P. is given, the valve cylinder stress P. Unbalance stress σ with parameter
. , the bending stress σ8 is calculated, and the resultant stress σ□=
σ5+σ. is the output of the valve stem static stress calculation section 6, that is, the static stress of the fatigue strength calculation section 7.

In addition to this, the valve stem fatigue strength calculation unit 7 receives the acceleration 6° and the amplitude value, which are the vibration values of the valve stem during operation, from the valve stem vibration measurement unit 3. is input. By inputting the acceleration G0, the force acting on the valve stem due to the vibration acceleration is calculated as (mass of the valve stem, etc. x acceleration G), and the stress on the valve stem at that time is σG. On the other hand, the amplitude value M. This amplitude value is better than that. The valve stem bending stress σNo due to vibration is calculated assuming that a forced bending force acts on the tall valve stem.

The amplitude value of the bending stress σHa of the valve stem due to vibration further changes due to the change in the gap value cIl between the valve stem 1b and the valve stem bush 1c, that is, the bending stress σ8°, so the gap value cff
must be taken as a parameter.

FIG. 3 is a diagram illustrating each stress value in the fatigue strength calculation section. Vibration acceleration G. When is input, vibration acceleration G.

This indicates that the valve stem stress σ6o can be obtained with a magnitude proportional to , and the vibration amplitude value M.

is input, the valve stem bending stress σ due to the amplitude is calculated using the gap value cQ1 between the valve stem 1b and the valve stem bushing IC as a parameter.
Me will be required. The fluctuating stress value (σHn + σ(io)) acting on these valve stems is the composite fluctuating stress σ
2(0M.+σco) and the valve stem static stress σ, are calculated as the overall stress σ,2 acting on the valve stem.

In Figure 3, the curve n-n represents the fatigue limit diagram of the material used for the valve stem 1b, where point A represents the fatigue limit, point B represents the yield point, and point 0 represents the tensile strength. .

The overall stress value σI2 acting on the above valve stem is shown in Figure 3.
If it is within the safety range indicated by ADB, there is no problem with the strength of the valve stem 1b, but for example, the vibration acceleration of the valve stem increases and G
1, the vibration amplitude value increases and becomes A□, and furthermore, due to these vibration increases, the gap of the valve stem sliding part becomes cQ from cQl.
2, the valve stem stress due to acceleration changes to G6, the valve stem bending stress due to amplitude changes to σM, and the resultant fluctuating stress also becomes G3 (σ, 1061). The total acting stress with the valve stem static stress σ is σ3. As a result, it falls outside the safe area (OADB) in Fig. 3 and into the dangerous area.

If the calculation result in the valve stem fatigue strength calculation unit 7 is within the safe range, the judgment unit 9 makes a judgment and finishes the diagnosis, but if the calculation result is in the dangerous range, the alarm output unit 10 outputs fatigue data accumulation. Each signal is output to the section 11.

The alarm output section 10 notifies the plant operator that the steam control valve 1 is currently operating in a large vibration region using, for example, a speaker 12, and if the power supply situation permits, outputs a load request signal section. It is also possible to output a request signal to move the steam control valve 1 to a region where the valve stem vibration becomes smaller.

On the other hand, the signal input to the fatigue data storage section 11 indicates the operating time in the dangerous area and the valve stem fatigue strength calculation input data (valve stem lift 1 to Q4, main steam pressure P., valve stem static stress σ8). , vibration acceleration G8, amplitude value H□, etc.),
Information will be stored. The vibration of the valve stem of the steam control valve 1 is extremely large, and even if the fatigue strength is within the danger range, it is rare that the valve stem will be damaged immediately, such as breakage.
This will lead to damage depending on the operating time.

FIG. 5 is a diagram showing the relationship between fatigue strength and allowable operating time. For example, when operating at fatigue strength σ9, T. This indicates that continuous operation is possible. This time T. If it exceeds this, damage to the valve stem will result. However, during operation, the operating condition of the steam control valve changes with time, and therefore the fatigue strength σ, 3 also changes sequentially.

The valve stem fatigue data storage unit 11 has a function of calculating the remaining life of the valve stem of the steam control valve 1 from the operating time and the fatigue strength of the valve stem. Ru. Note that here σEo+To+ σEi+
T0. σE21T2 are each T at the valve stem fatigue strength σE0, for example. This indicates that the vehicle has been operated for a certain amount of time.

When the remaining life of the valve stem in the valve stem fatigue data storage section 11 exceeds a certain value, the data accumulation section 11 outputs to the operator via the alarm output section 10 that the remaining life of the valve stem is short. It enables planned maintenance by outputting the necessity of disassembly and inspection during periodic inspections or the necessity of new product replacement.

〔Effect of the invention〕

As explained above, according to the steam regulating valve vibration diagnosis device of the present invention, it is possible to continuously monitor the vibration of the valve stem of the steam regulating valve, and when the vibration is in the dangerous range, the operator can Not only is the system notified immediately, but driving restrictions can be added, allowing for safer driving.

In addition, if operation in the hazardous area continues, the remaining service life of the valve stem is estimated, inspection during periodic inspections, disassembly instructions are output, or the need for new parts is output in response to the operator's request. etc.
Planned maintenance becomes possible.

Furthermore, the valve stem fatigue strength calculation of this diagnostic device is based on the latest information such as correction of main steam pressure and valve assembly information, so highly reliable information regarding safety can be obtained. It has excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between the load request signal and valve lift, and Fig. 3 is a diagram showing the static stress of the valve stem, the vibration value of the valve stem, and the variable stress of the valve stem. Figure 4 is a diagram showing the relationship between valve lift and valve stem static stress, Figure 5 is a diagram showing the relationship between operating time and valve stem fatigue strength, and Figure 6 is a diagram showing the relationship between valve lift and valve stem static stress. 7 is a diagram showing the relationship between valve lift and valve vibration, and FIG. 7 is a diagram showing the relationship between load request signal, control valve lift, and vibration value. 1 Steam control valve 2...Vibration sensor 3...Valve stem vibration measurement section 4...Valve opening calculation section 5...Load request signal section 6...Valve stem static stress calculation section 7... Fatigue strength calculation section 8...Assembly adjustment recording section 9...Judgment section 10...Alarm output section 11...Fatigue data accumulation section 12...Speaker (8733) Representative patent attorney Inoko (and others) No.

Claims (1)

[Claims] In a vibration diagnosis device for multiple steam control valves that control the flow rate of a steam turbine, there is a valve opening calculation unit that calculates the valve opening based on a signal from a load request signal unit, and a valve stem that is affected by the valve front pressure. A calculation unit that calculates the static stress, a vibration sensor,
It is characterized by being equipped with a calculation section that calculates the fluctuating stress on the valve stem from the data of the vibration measurement section and the assembly dimension recording section, and configured to be able to output an alarm and impose operational restrictions when the stress acting on the valve stem is in a dangerous range. Steam control valve vibration diagnosis device.