CA1153114A - Method of sensing malfunctions of check valve mounted in pipeline and apparatus therefor - Google Patents
Method of sensing malfunctions of check valve mounted in pipeline and apparatus thereforInfo
- Publication number
- CA1153114A CA1153114A CA000365334A CA365334A CA1153114A CA 1153114 A CA1153114 A CA 1153114A CA 000365334 A CA000365334 A CA 000365334A CA 365334 A CA365334 A CA 365334A CA 1153114 A CA1153114 A CA 1153114A
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- Prior art keywords
- check valve
- dynamic pressure
- valve
- normal operation
- valve opening
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- 230000007257 malfunction Effects 0.000 title claims description 25
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 5
- 239000012530 fluid Substances 0.000 claims description 21
- 230000002159 abnormal effect Effects 0.000 claims description 11
- 238000013461 design Methods 0.000 claims description 10
- 238000005070 sampling Methods 0.000 claims description 7
- 238000012544 monitoring process Methods 0.000 claims description 6
- 230000005856 abnormality Effects 0.000 abstract description 14
- 238000003745 diagnosis Methods 0.000 abstract description 9
- 230000006870 function Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000011010 flushing procedure Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000009897 systematic effect Effects 0.000 description 2
- FBOUIAKEJMZPQG-AWNIVKPZSA-N (1E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol Chemical compound C1=NC=NN1/C(C(O)C(C)(C)C)=C/C1=CC=C(Cl)C=C1Cl FBOUIAKEJMZPQG-AWNIVKPZSA-N 0.000 description 1
- 208000036366 Sensation of pressure Diseases 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000881 depressing effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
- Check Valves (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method of diagnosis of the operating condi-tions of a swing-type check valve mounted in a pipeline, wherein normal operation data are prepared which represent tolerances for the opening of the check valve with respect to the dynamic pressure of the flow of a stream upstream of the check valve which are set beforehand, and data representing the actual operating conditions of the check valve are prepared by actually detecting the dynamic pressure and valve opening when diagnosis is made. The data representing the actual operating conditions of the check valve are compared with the normal operation data stored in a memory, whereby the presence or absence of abnormality in the check valve can be diagnosed.
A method of diagnosis of the operating condi-tions of a swing-type check valve mounted in a pipeline, wherein normal operation data are prepared which represent tolerances for the opening of the check valve with respect to the dynamic pressure of the flow of a stream upstream of the check valve which are set beforehand, and data representing the actual operating conditions of the check valve are prepared by actually detecting the dynamic pressure and valve opening when diagnosis is made. The data representing the actual operating conditions of the check valve are compared with the normal operation data stored in a memory, whereby the presence or absence of abnormality in the check valve can be diagnosed.
Description
This invention relates to a method of sensing mulfunctions of a check valve, particularly a swing-type check valve, mounted in a pipeline during operation and an apparatus suitable for carrying the method into practice.
A swing-type check valve is a valve mounted for preventing the backflow of a fluid, which generally comprises a valve disk of the disk shape supported by an arm which ln turn is pivotally supported at its upper end, to enable the valve disk to move in swinging movement between an open position and a closed position.
In operation, the valve disk is moved upwardly by a fluid when the fluid flows in a predetermined direction to open the valve, and the valve disk moves downwardly by its own weight when the flow of the fluid is inter-rupted. The backflow of the fluid lets the valve disk move downwardly, in cooperation with the weight of the valve body.
A check valve of the swing-type of the afore-said construction is mounted in various positions.
Typical of this type of valves mounted in a steam turbine generating plant include a check valve mounted on the discharge side of a feedwater pump and an extracted steam check valve mounted in an extracted -11~311~
1 steam line of the turbine. Malfunctions of these check valves would result in damage to the main machines because the backflow of the fluid could not be prevented.
~or example, malfunctions of the check valve on the discharge side of the feedwater pump might result in the feedwater pump being run in the reverse direction by the high pressure water flowing backwardly, so that excessive vibration might be generated or sliding damage or other damage might be caused in some cases.
In the event that the extracted steam check valve of the turbine fails to function normally at the time the turbine is tripped, the saturated water in the feedwater heater would flow backwardly into the turbine in flushing movement, thereby giving sudden thermal shock to the inner walls of the turbine. This might cause thermal deformation or crack formation or accelerate the rotation of the turbine shaft, thereby causing serious accidents. Thus, in order that the main machines may be provided with protection from damage, it is important that the check valve operate normally at all times.
Particularly, it is lmportant that the extracted steam check valve operate normally at all times, because it is one of the means for protecting the turbine. In view of this, the general tendency in turbine plants is to adopt an extracted steam check valve of the pneumatically operated type which is a check valve of the swing-type provided with ~1~3114 1 pneumatic valve operating means. The extracted steam check valve of the pneumatically operated type comprises a spring-loaded pneumatic cylinder which can move the valve disk to a closed position. During operation, the valve disk is moved by the pneumatic cylinder at regular intervals to prevent the valve disk from being stuck, and the manner of operation of the valve disk is checked visually by the operator to determine whether or not the valve disk is operating smoothly, to detect malfunctions of the valve at early stages. While this type of extracted steam check valve of the pneumatically operated type is used nowadays, the present practice is to effect supply and discharge of air for operating the valve through an electromagnetic valve by depressing a button in the central control room to carry out tests on the operation of the check valve and to check the operation of the check valve by sensing its operation by means of a limit switch and lighting a lamp by a signal generated by the limit switch, without visually checking the operation of the valve on the spot, to save labor generally and to reduce the hazards of exposure to radioactivity in a nuclear power plant. Thus difficulties are encounter-ed nowadays in detecting malfunctions of not only a check valve of the swing-type but also an extracted steam check valve of the pneumatically operated type during operation. It is quite difficult to sense the occurrence of a serous accident involving the 3~14 dislodging of a valve disk, for example in extreme cases.
SUMI~RY OF THE INVENTION
This invention has as its object the provision of a method of monitoring the operating conditions of a check valve mounted in a pipeline, the method being capable of sensing abnormalities of the check valve and detecting malfunctions thereof at early stages, and apparatus suitable for carrying such method into practice.
According to the invention, there is provided a method of monitoring the operating conditions of a check valve mounted in a pipeline, comprising the steps of:
obtaining actual data by measuring a degree of opening of said check valve and a dynamic pressure of the flow of a fluid through the pipeline; and comparing in a judging unit the actual data with normal operation data stored beforehand in a memory, said normal operation data representing relations between degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating conditions of the check valve, whereby operating condition of the check valve can be monitored to determine whether or not the check valve has malfunctions, said steps being carried out automatically.
The invention also consists of an apparatus for monitoring the operating conditions of a swing-type check valve mounted in a pipeline, comprising first means for detecting the degree of opening of said check valve and .
producing a valve opening signal; second means for detecting the dynamic pressure of the flow of a fluid upstream of said check valve and producing a dynamic pressure signal; normal operation data memory for storing normal operation data representing relations between degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating conditions of the check valve; and a judg-ing unit connected to said first means, second means and normal operation data memory to receive said valve opening signal, said dynamic pressure signal and said normal operation data, said judging unit functioning to prepare actual data representing the relation between the detected degree of opening of the check valve and the detected dynamic pressure and to compare the actual data with said normal operation data, whereby the operating condition of the check valve is monitored to determine whether or not the check valve has malfunctions.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a systematic diagram of a turbine extracted steam system incorporating therein one embodiment of the present invention;
Fig. 2 is a sectional view of the check valve - 4a -i~S3~14 1 mounted in the turbine extracted steam system shown in Fig. l;
Fig. 3 is a diagram in explanation of the valve opening characteristics of the check valve shown in Fig. 2, Fig. 4 is a view showing in detail the const-ruction of the apparatus for diagnosing the operating conditions of the check valve;
Fig. 5 is a flow chart for preparing data indicating the normal operating conditions of the check valve; and Fig. 6 is a flow chart for diagnosing the presence or absence of abnormality in the check valve.
~ESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described by referring to an embodiment adapted for use with an extracted steam check valve mounted in an extracted steam system of a fossil fuel power generating plant.
Fig. 1 is a systematic diagram of an extracted steam system comprising an extracted steam line 12 connected to a turbine 11 at one end thereof and to a feedwater heater 14 via an extracted steam check valve 13 at the other end thereof. The steam extracted from the turbine 11 is supplied via the extracted steam check valve 13 to the feedwater heater 14 through which a feedwater line 15 extends so that the feedwater flowing through the line 15 is heated by the steam supplied through the extracted steam line 12.
115311~
1 A drain 16 is connected to the feedwater heater 14 for discharging condensate therethrough.
The check valve 13 is mounted for the purpose of preventing the saturated water in the feedwater heater 14 from flowing back to the turbine 11 in flushing movement when the turbine is tripped. As shown in Fig. 2, the extracted steam check valve 13 comprises a valve disk 2 of the disk shape mounted in a valve box 1 and secured to a lower end of an arm 3 which is secured at an upper end to a valve shaft 4 rotatably supported in the valve box 1. Thus the valve disk 2 can be moved from a closed position shown in Fig. 2 to an open position as it is pushed by the flow of fluid directed from right to left in the figure and the valve shaft 4 rotates clockwise in the figure.
The position in which the valve shaft 4 is mounted and the weight of the valve disk 2 are selected such that when there is no flow of fluid through the check valve 13 the valve disk 2 moves by its own weight to the closed position, and as the flow of fluid increases the degree of opening of the valve 13 increases until the valve disk 2 moves to the full open position at 60 -80% of the rated flow rate of fluid in the extracted steam line 12. The valve shaft 4 extends outwardly of the valve box 1 (in a direction perpendicular to the plane of Fig. 2) and has connected thereto an actuator 24 (See Fig. 1) for moving the valve disk 2 to the closed position.
~15~il4 1 Referring to Fig. 1 again, the check valve 13 has connected thereto a valve opening detector 22 ~or detecting the degree of opening of the valve 13.
The valve opening detector 22 detects an angle of rotation of the valve shaft 4 supporting the valve disk
A swing-type check valve is a valve mounted for preventing the backflow of a fluid, which generally comprises a valve disk of the disk shape supported by an arm which ln turn is pivotally supported at its upper end, to enable the valve disk to move in swinging movement between an open position and a closed position.
In operation, the valve disk is moved upwardly by a fluid when the fluid flows in a predetermined direction to open the valve, and the valve disk moves downwardly by its own weight when the flow of the fluid is inter-rupted. The backflow of the fluid lets the valve disk move downwardly, in cooperation with the weight of the valve body.
A check valve of the swing-type of the afore-said construction is mounted in various positions.
Typical of this type of valves mounted in a steam turbine generating plant include a check valve mounted on the discharge side of a feedwater pump and an extracted steam check valve mounted in an extracted -11~311~
1 steam line of the turbine. Malfunctions of these check valves would result in damage to the main machines because the backflow of the fluid could not be prevented.
~or example, malfunctions of the check valve on the discharge side of the feedwater pump might result in the feedwater pump being run in the reverse direction by the high pressure water flowing backwardly, so that excessive vibration might be generated or sliding damage or other damage might be caused in some cases.
In the event that the extracted steam check valve of the turbine fails to function normally at the time the turbine is tripped, the saturated water in the feedwater heater would flow backwardly into the turbine in flushing movement, thereby giving sudden thermal shock to the inner walls of the turbine. This might cause thermal deformation or crack formation or accelerate the rotation of the turbine shaft, thereby causing serious accidents. Thus, in order that the main machines may be provided with protection from damage, it is important that the check valve operate normally at all times.
Particularly, it is lmportant that the extracted steam check valve operate normally at all times, because it is one of the means for protecting the turbine. In view of this, the general tendency in turbine plants is to adopt an extracted steam check valve of the pneumatically operated type which is a check valve of the swing-type provided with ~1~3114 1 pneumatic valve operating means. The extracted steam check valve of the pneumatically operated type comprises a spring-loaded pneumatic cylinder which can move the valve disk to a closed position. During operation, the valve disk is moved by the pneumatic cylinder at regular intervals to prevent the valve disk from being stuck, and the manner of operation of the valve disk is checked visually by the operator to determine whether or not the valve disk is operating smoothly, to detect malfunctions of the valve at early stages. While this type of extracted steam check valve of the pneumatically operated type is used nowadays, the present practice is to effect supply and discharge of air for operating the valve through an electromagnetic valve by depressing a button in the central control room to carry out tests on the operation of the check valve and to check the operation of the check valve by sensing its operation by means of a limit switch and lighting a lamp by a signal generated by the limit switch, without visually checking the operation of the valve on the spot, to save labor generally and to reduce the hazards of exposure to radioactivity in a nuclear power plant. Thus difficulties are encounter-ed nowadays in detecting malfunctions of not only a check valve of the swing-type but also an extracted steam check valve of the pneumatically operated type during operation. It is quite difficult to sense the occurrence of a serous accident involving the 3~14 dislodging of a valve disk, for example in extreme cases.
SUMI~RY OF THE INVENTION
This invention has as its object the provision of a method of monitoring the operating conditions of a check valve mounted in a pipeline, the method being capable of sensing abnormalities of the check valve and detecting malfunctions thereof at early stages, and apparatus suitable for carrying such method into practice.
According to the invention, there is provided a method of monitoring the operating conditions of a check valve mounted in a pipeline, comprising the steps of:
obtaining actual data by measuring a degree of opening of said check valve and a dynamic pressure of the flow of a fluid through the pipeline; and comparing in a judging unit the actual data with normal operation data stored beforehand in a memory, said normal operation data representing relations between degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating conditions of the check valve, whereby operating condition of the check valve can be monitored to determine whether or not the check valve has malfunctions, said steps being carried out automatically.
The invention also consists of an apparatus for monitoring the operating conditions of a swing-type check valve mounted in a pipeline, comprising first means for detecting the degree of opening of said check valve and .
producing a valve opening signal; second means for detecting the dynamic pressure of the flow of a fluid upstream of said check valve and producing a dynamic pressure signal; normal operation data memory for storing normal operation data representing relations between degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating conditions of the check valve; and a judg-ing unit connected to said first means, second means and normal operation data memory to receive said valve opening signal, said dynamic pressure signal and said normal operation data, said judging unit functioning to prepare actual data representing the relation between the detected degree of opening of the check valve and the detected dynamic pressure and to compare the actual data with said normal operation data, whereby the operating condition of the check valve is monitored to determine whether or not the check valve has malfunctions.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a systematic diagram of a turbine extracted steam system incorporating therein one embodiment of the present invention;
Fig. 2 is a sectional view of the check valve - 4a -i~S3~14 1 mounted in the turbine extracted steam system shown in Fig. l;
Fig. 3 is a diagram in explanation of the valve opening characteristics of the check valve shown in Fig. 2, Fig. 4 is a view showing in detail the const-ruction of the apparatus for diagnosing the operating conditions of the check valve;
Fig. 5 is a flow chart for preparing data indicating the normal operating conditions of the check valve; and Fig. 6 is a flow chart for diagnosing the presence or absence of abnormality in the check valve.
~ESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described by referring to an embodiment adapted for use with an extracted steam check valve mounted in an extracted steam system of a fossil fuel power generating plant.
Fig. 1 is a systematic diagram of an extracted steam system comprising an extracted steam line 12 connected to a turbine 11 at one end thereof and to a feedwater heater 14 via an extracted steam check valve 13 at the other end thereof. The steam extracted from the turbine 11 is supplied via the extracted steam check valve 13 to the feedwater heater 14 through which a feedwater line 15 extends so that the feedwater flowing through the line 15 is heated by the steam supplied through the extracted steam line 12.
115311~
1 A drain 16 is connected to the feedwater heater 14 for discharging condensate therethrough.
The check valve 13 is mounted for the purpose of preventing the saturated water in the feedwater heater 14 from flowing back to the turbine 11 in flushing movement when the turbine is tripped. As shown in Fig. 2, the extracted steam check valve 13 comprises a valve disk 2 of the disk shape mounted in a valve box 1 and secured to a lower end of an arm 3 which is secured at an upper end to a valve shaft 4 rotatably supported in the valve box 1. Thus the valve disk 2 can be moved from a closed position shown in Fig. 2 to an open position as it is pushed by the flow of fluid directed from right to left in the figure and the valve shaft 4 rotates clockwise in the figure.
The position in which the valve shaft 4 is mounted and the weight of the valve disk 2 are selected such that when there is no flow of fluid through the check valve 13 the valve disk 2 moves by its own weight to the closed position, and as the flow of fluid increases the degree of opening of the valve 13 increases until the valve disk 2 moves to the full open position at 60 -80% of the rated flow rate of fluid in the extracted steam line 12. The valve shaft 4 extends outwardly of the valve box 1 (in a direction perpendicular to the plane of Fig. 2) and has connected thereto an actuator 24 (See Fig. 1) for moving the valve disk 2 to the closed position.
~15~il4 1 Referring to Fig. 1 again, the check valve 13 has connected thereto a valve opening detector 22 ~or detecting the degree of opening of the valve 13.
The valve opening detector 22 detects an angle of rotation of the valve shaft 4 supporting the valve disk
2 through the arm 3 and generates a valve opening signal commensurate with the detected angle of rotation of the valve shaft 4. Any known type of valve opening detector may be used. A dynamic pressure detector 21 for detecting a dynamic pressure of a fluid flowing through the extracted steam line 12 is mounted in the extracted steam line 12 connected to the upstream side of the check valve 13 and generates a dynamic pressure signal. The valve opening detector 22 and dynamic pressure detector 21 are connected to a valve operating conditoin diagnosing apparatus 23 which is to be subsequently described in detail.
Prior to the description o~ the valve operat-ing condition diagnosing apparatus 23, the valve opening characteristics of the check valve 13 will be outlined.
A pressure loss in the extracted steam check valve 13 is generally expressed by the following equation:
2g (1) where ~P: the pressure loss in extracted steam check valve.
~: the pressure loss coef~icient.
~1~3~14 1 ~: the flow rate of fluid.
y: the specific weight of fluid.
g: the acceleration of gravity.
The pressure loss coefficient ~ is a coef-ficient which may vary depending on the valve opening
Prior to the description o~ the valve operat-ing condition diagnosing apparatus 23, the valve opening characteristics of the check valve 13 will be outlined.
A pressure loss in the extracted steam check valve 13 is generally expressed by the following equation:
2g (1) where ~P: the pressure loss in extracted steam check valve.
~: the pressure loss coef~icient.
~1~3~14 1 ~: the flow rate of fluid.
y: the specific weight of fluid.
g: the acceleration of gravity.
The pressure loss coefficient ~ is a coef-ficient which may vary depending on the valve opening
3 of the check valve 13. Meanwhile in a swing-type check valve, the pressure differential between the front and the rear of the valve disk provides a force urging the valve disk to open, and the weight of the valve disk provides a force urging the valve disk to close, so that the valve disk is maintained at a degree of opening at which these forces balance. Stated dif-ferently, the valve opening 3 is a function of the pres-sure loss ~P. Therefore, the valve opening 3 can be expressed by equation (2) as follows as a function of 2Y in equation (1):
g ~ = F (~2Y) ----------------- (2) where ~2Y is the dynamic pressure of the flow of fluid through the extracted steam line 12. Thus the valve opening of the check valve 13 is a function of the dynamic pressure of the fluid.
Fig. 3 shows one example of the valve opening in relation to the dynamic pressure (~2y/2g). In the figure, a curve A1 represents valve opening characteristic with respect to the dynamic pressure which is obtained when the flow rate of steam through the extracted steam ~ 5;~
1 line 12 is gradually increased or the dynamic pressure is gradually increased, and a curve A2 represents valve opening characteristic with respect to the dynamic pressure which is obtained when the dynamic pressure is gradually reduced. As can be seen in curve Al, the valve opening gradually increases with an increase in dynamic pressure until the full open level is achieved when the dynamic pressure reaches about 80% of the dynamic pressure at the time of steady state operation as indicated at P 1 Thereafter, the valve 13 is maintained at the full open level. On the other hand, when the dynamic pressure is reduced from the steady state operation condition, the check valve 13 begins to close when the dynamic pressure reaches Po2 at which the dynamic pressure is lower than at ~ol as shown ln curve A2. Thereafter, the valve opening is reduced as the dynamic pressure is reduced. Thus it will be seen that to attain the same degree of valve opening, a higher dynamic pressure is required when the dynamic pressure is increasing than when it is decreasing. This phenomenon is accounted for by hysteresis due to friction of the valve shaft and other factors.
During the normal operation of the check valve 13, the valve opening VH and the dynamic pressure PO have the characteristics represented by curves Al and A2 in Fig. 3. However, in the event that abnormality is present in the check valve 13, the valve opening V~
_ 9 _ ~.~531~4 1 and the dynamic pressure PO will have charactersitics which deviate from the characteristics represented by curves Al and A2. For example, when the valve disk 2 difficultly moves and hysteresis becomes excessively great, the check valve 13 will have valve opening characteristics represented by curves Bl and B2.
When the valve 13 is stuck in the full open position, the valve opening characteristic will be represented by a line C. When the valve disk 2 is dislodged and the valve 13 is not apparently opened, the valve opening characteristic will be represented by a line D. When the valve disk 2 does not close smoothly, the valve opening characteristic will be represented by a line E. Thus if the valve opening characteristics (curves Al and A2) of the check valve 13 for the normal operation are known, then it is possible to ~udge the presence or absence of abnormality in the check valve 13 at an arbitrarily selected time by measuring the actual valve opening and the dynamic pressure and comparing the data thus obtained with the data for the normal operation of the valve representing the normal valve opening characteristics.
The present inventoin is based on the characteristics of the valve described hereinabove.
As described hereinabove and shown in Fig. 1, the dynamic pressure detector 21 is mounted in the extracted steam line 12 connected to the upstream side of the check valve 13, and the valve opening detector 22 is mounted ~` ` ;
~lS311~
1 on the check valve 13. In the illustrated embodiment, the dynamic pressure detector 21 is of the type which directly senses the dynamic pressure in the extracted steam line 12 and produces a dynamic pressure signal.
However, the invention is not limited to this type of dynamic pressure detector and any other type of sensing means capable of producing as a dynamic pressure signal a signal indicating the dynamic pressure of the fluid in any form may be used. For example, an orifice may be formed in the exeracted steam line 12 and means for measuring the pressure differential QP' between the front and the rear of the orifice may be provided for producing an output signal associated with the pressure differential QP' as a dynamic pressure signal.
In this case, the pressure differential ~P' between the front and the rear of the orifice can be expressed as the product of the dynamic pressure (~2~/2g) and the pressure loss coefficient as in the case of the check valve expressed by equation (1). Since the pressure loss coefficient is constant, the differential pressure QP' is after all proportional to the dynamic pressure and can be used as a dynamic pressure signal. Besides, the flow rate of fluid through the extracted steam check vlave 13 or the load on the plant can be used as dynamic pressure signals because they are definably related to the dynamic pressure.
In the illustrated embodiment, the valve opening detector 22 is of the type that detects the 1153~1~
1 angle of rotation of the valve shaft 4. Generally, the valve disk of a swing-type check valve has a small angle of deviation (the degree of valve opening at full open position relative to that at full closed position) of 40 - 50. Thus, besides measuring the angle of rotation, the distance of movement (straight line dis-tance) on a chord may be detected and used as a valve opening signal.
The valve opening signal generated by the valve opening detector 22 and the dynamic pressure signal generated by the dynamic pressure detector 21 are supplied to the valve operating condition diagnosing apparatus 23 where the operating conditions of the extracted steam check valve 13 are diagnosed.
The valve operating condition diagnosing apparatus 23 may be in the form of a digital data processor which samples the valve opening signal and the dynamic pressure signal at suitable intervals of time and compares them with the data stored therein, to keep an eye on the operation of the check valve. More speci-fically, the data representing the normal operation of the check valve 13 which include the curves Al and A2 shown in Fig. 3 and representing the valve opening characteristics plus tolerances are stored as normal operation data, and the check valve 13 is ~udged as having normalcy or abnormality depending on whether or not the data obtained by actual measuring including the valve open-ing and the dynamic pressure actually measured at each sampling time are within the aforesaid tolerances.
'1153114 1 The diagnosis is carried on not only when the turbinesystem is in steady state operation but also when it is shut down or at startup. The diagnosis is usually carried out at a cycle of 0.2 to 10 seconds. However, at the time of steady state operation, the diagnosis may be performed at a cycle of longer duration, and when the extracted steam check valve 13 is suddenly closed as when the turbine is tripped, t,he diagnosis may be performed in a cycle of shorter duration of 0.01 to 0.1 second. The check valve 13 may be ~udged to have abnormality when the data obtained by actual measuring at a single sampling are not within the tolerances of the normal operation data stored. Alternatively, the ~udgement of abnormality may be passed only when the data obtained by actual measuring at a series of sampl-ing are not within the tolerances of the normal operation data stored.
The data representing the normal operation of the turbine stored in the turbine operating condition diagnosing apparatus 23 are first calculated from the valve opening characteristic design values and the desired tolerances, and the data obtained by actual measuring are compared with the stored data of normal operation at the time of trial operation of the plant and following disassembling and checking of the check valve at the time of periodic inspection, to judge whether or not the check valve is operating normally.
When the data obtained by actual measuring at the time 115;3114 1 the operation of the turbine is initiated are judged to ind~cate the presence o~ no abnormality in the check valve, such data are stored and characteristic curves based on the data obtained by actual measuring are prepared. The characteristic curves prepared in this way are used to correct the data of normal operation, so that the corrected data can be used in subsequent diagnosis as fresh normal operation data.
The method of diagnosis of the operating conditions of the check valve according to the invention will now be described in concrete terms by referring to Figs. 3 - 6. Fig. 4 shows the construction of the valve operating condition diagnosing apparatus 23 shown in Fig. 1. At initial stages of turbine plant operation, the design values of valve opening characteristics and tolerances therefor are fed into a normal operation data memory 31, to store the tolerances for the normal operation data. Then, at the time of the trial operation of the turbine plant, a dynamic pressure signal Poi from the dynamic pressure detector 21 and a valve opening signal VHi from the valve opening detector 22 shown in Fig. 1 are supplied at each of a series of diagnosing cycles to a ~udging unit 32, where the normal operation data transmitted from the normal operation data memory 31 are compared with the data obtained by actual measuring of the dynamic pressure signal and valve opening signal (Poi and VHi) to determine whether or not the latter are within the llS3~1~
1 tolerances for the normal operation data, to thereby judge the presence or absence of abnormality in the check valve 13. When the check valve 13 is judged to have abnormality, a signal is forwarded to a malfunc-tion indicator 35 to indicate the presence of malfunc-tion. Meanwhile when no malfunctions are found, the data obtained by actual measuring (Poi and VHi) are supplied from the ~udging unit 32 to a switch 33. At the time of the trial operation of the turbine plant, a selection signal of an ON position is supplied to the switch 33, so that the data obtained by actual measuring (Poi and VHi) are supplied via the switch 33 to a valve opening characteristi~s memory 34 and stored therein. When the data obtained by actual measuring and stored in the memory 34 exceed a predetermined level of number with respect to different dynamic pressures and actually measured valve opening characteristics are obtained, they are inputted to the normal operation data memory 31. At the same time, tolerances (input data) for the actually measured valve opening characteristics are also fed into normal operation data memory 31, so that the tolerances for the normal operation data determined previously based on the valve opening characteristic design values are corrected by the data obtained at the time of the actual operation of the turbine plant. The corrected normal operation data are stored as fresh normal opera-tion data. Thereafter, data obtained by actual measuring (Poi and VHi) are judged by the fresh normal operation llS31~4 1 data. Following the correction of the normal operation data stored in the normal operation data memory 31, the se:Lection signal is switched to an OFF position and the switch 33 no longer allows the data obtained by actual measuring to be supplied to the normal operation data memory 31.
When the data obtained by actual measuring (Po1 and VHi) are judged to indicate abnormality by the judging unit 32, the data (Poi and VHi) are supplied to a valve opening charactersitics memory 36 and stored therein. When the data obtained by actual measuring exceed a predetermined level of number with respect to different dynamic pressures, an abnormal valve opening characteristics are stored in the memory 36. Meanwhile a malfunction pattern memory 37 has stored therein abnormal valve opening characteristics (as represented by Bl, B2, C, D and E in Fig. 3, for example) due to different causes of malfunction. Thus the valve opening characteristics stored in the memory 36 are compared with the malfunction patterns stored in the malfunction pattern memory 37 at a malfunction cause ~udging unit 38, so that the cause of the malfunction is judged by the ~udging unit 38 and the ~udgment is indicated by a malfunction cause indicator 39.
Figs. 5 and 6 are flow charts showing data processing preformed by the valve operating condition diagnosing apparatus 23. The flow chart shown in 1153~1~
1 Fig. 5 deals with data processing for preparing normal operation data, wherein design values 102 for the valve opening characteristics and tolerances 103 for the design values 102 are fed into the apparatus 23 at initial stages 101 of turbine plant operation.
The design values of valve opening characteristics include a valve opening characteristic at the time of increasing dynamic pressure and a valve opening characteristic at the time of reducing dynamic pressure each represented by data of 5 to 10 points [each point is represented by (PO and VH) in which the dynamic pressure PO and the valve opening VH associated there-with form a set of data]~ The tolerances include a dynamic pressure tolerance QPO and a valve opening tolerance ~VH for accommodatlng variations with respect to each valve openlng characteristics data point (PO and VH), and the range of allowable variations for the valve opening data point is set at (PO + ~PO and VH ~ ~VH~. The data points are inter-polated by a straight line or smooth curve.
Allowable valve opening characteristicsessentially have two bands representing values deter-mined at the time of increasing dynamic pressure and at the time of reducing dynamic pressure respectively.
However, the hysteresis caused by frictional resistance tends to increase with time, so that the tolerances may be represented by one band as shown at 106 in Fig. 5.
Thus allowable valve opening characteristics 106 are .
' 1~L53~14 1 prepared in this way and registered as normal operation data as indicated at 107. When the turbine plant performs other operations than an initial stage opera-tion (mainly when a trial operation is performed), values representing the actual results of operation are inputted as indicated at 104 in place of the design values, and tolerances for the values representing the actual results of operation are also inputted as indicated at 105. These data are processed in the same manner as described hereinabove to obtain normal operation data.
~ he flow chart shown in Fig. 6 deals with the process for diagnosing the operating conditions of the check valve 13. Data obtained by actual measuring (Po1 and VHi) are fed into the diagnosing apparatus 23 as indicated at 111 each time sampling is carried out, and compared with the normal operation data obtained as described by referring to Flg. 5 as indicated at 112. When the data obtained by actual measuring are within the tolerances for the normal operation data, the check valve is judged to be operating normally;
and when they are not within the tolerances, the check valve is judged to have malfunction. When the check valve is ~udged to have malfunction as indicated at 113, a check valve malfunction warning is issued as indicated at 114 and at the same time a valve opening characteristic for the abnormal data is prepared as indicated at 115.
The valve opening characteristics for the malfunction .
1 data are compared with valve opening characteristics prepared beforehand for different causes of valve mal-functions, to determine the cause of the particular valve malfunction. When the data obtained by actual measuring are judged to indicate a normal operation of the check valve in the diagnosis of the operating conditions shown in Fig. 6, the next following sampling is performed. Particularly when a record of the valve opening characteristics for the normal operation of the check valve is made as indicated at 118 (input data give instructions on the need to prepare such record), data obtained by actual measuring are stored to provide valve opening characteristics as indicated at 119. When the turbine plant is operated as a trial operation, normal operation data are prepared based on the values representing the actual results of operation as described hereinabove by referring to Fig. 5.
In the embodiment shown and described herein-above, normal operation data including normal valve opening characteristics plus tolerances are prepared, and the presence or absence of abnormality in the check valve is ~udged by determining whether or not the data obtained by actual measuring are within the tolerances.
It is to be understood, however, that the invention is not limited to this specific form of the embodiment, and that various changes and modifications may be made therein. One example o~ such modifications will be 1~ 53114 1 described by referring to Fig. 3. In one modification, the normal valve opening characteristic curves Al and A2 are used as normal operation data, and the actually measured valve opening characteristic curves Bl and B2 are prepared as representing data obtained by actual measuring. The operating conditions of the check valve are judged as being normal or abnormal by comparing these curves with one another. In comparing the curves, the judgement on whether the operating conditions of the check valve are normal or abnormal is passed based on the following findings:
a. The spacing between curve Al of the normal data and curve Bl of the data obtained by actual measuring or the dynamic pressure differential at a predetermined valve opening, or the spacing therebetween or the valve opening differential at a predetermined dynamic pressure;
b. The difference in the gradient between the curves at a predetermined valve opening or a predeter-mined dynamic pressure; andc. The ratio of one hysteresis to another hysteresis in the data (the ratio of a dynamic pressure differential a to a dynamic pressure differential _ in Fig. 3) at a predetermined valve opening, or the corresponding ratio of hysteresis at a predetermined dynamic pressure.
From the forégoing description, it will be appreciated that the present invention enables the - 20 _ ~153~1~
1 operating conditions of a check valve to be automati-cally dlagnosed during operation, to determine whether or not there is abnormality in the check valve.
While preferred embodiments of the invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and modifications may be made therein without departing from the spirit - or scope of the following claims.
g ~ = F (~2Y) ----------------- (2) where ~2Y is the dynamic pressure of the flow of fluid through the extracted steam line 12. Thus the valve opening of the check valve 13 is a function of the dynamic pressure of the fluid.
Fig. 3 shows one example of the valve opening in relation to the dynamic pressure (~2y/2g). In the figure, a curve A1 represents valve opening characteristic with respect to the dynamic pressure which is obtained when the flow rate of steam through the extracted steam ~ 5;~
1 line 12 is gradually increased or the dynamic pressure is gradually increased, and a curve A2 represents valve opening characteristic with respect to the dynamic pressure which is obtained when the dynamic pressure is gradually reduced. As can be seen in curve Al, the valve opening gradually increases with an increase in dynamic pressure until the full open level is achieved when the dynamic pressure reaches about 80% of the dynamic pressure at the time of steady state operation as indicated at P 1 Thereafter, the valve 13 is maintained at the full open level. On the other hand, when the dynamic pressure is reduced from the steady state operation condition, the check valve 13 begins to close when the dynamic pressure reaches Po2 at which the dynamic pressure is lower than at ~ol as shown ln curve A2. Thereafter, the valve opening is reduced as the dynamic pressure is reduced. Thus it will be seen that to attain the same degree of valve opening, a higher dynamic pressure is required when the dynamic pressure is increasing than when it is decreasing. This phenomenon is accounted for by hysteresis due to friction of the valve shaft and other factors.
During the normal operation of the check valve 13, the valve opening VH and the dynamic pressure PO have the characteristics represented by curves Al and A2 in Fig. 3. However, in the event that abnormality is present in the check valve 13, the valve opening V~
_ 9 _ ~.~531~4 1 and the dynamic pressure PO will have charactersitics which deviate from the characteristics represented by curves Al and A2. For example, when the valve disk 2 difficultly moves and hysteresis becomes excessively great, the check valve 13 will have valve opening characteristics represented by curves Bl and B2.
When the valve 13 is stuck in the full open position, the valve opening characteristic will be represented by a line C. When the valve disk 2 is dislodged and the valve 13 is not apparently opened, the valve opening characteristic will be represented by a line D. When the valve disk 2 does not close smoothly, the valve opening characteristic will be represented by a line E. Thus if the valve opening characteristics (curves Al and A2) of the check valve 13 for the normal operation are known, then it is possible to ~udge the presence or absence of abnormality in the check valve 13 at an arbitrarily selected time by measuring the actual valve opening and the dynamic pressure and comparing the data thus obtained with the data for the normal operation of the valve representing the normal valve opening characteristics.
The present inventoin is based on the characteristics of the valve described hereinabove.
As described hereinabove and shown in Fig. 1, the dynamic pressure detector 21 is mounted in the extracted steam line 12 connected to the upstream side of the check valve 13, and the valve opening detector 22 is mounted ~` ` ;
~lS311~
1 on the check valve 13. In the illustrated embodiment, the dynamic pressure detector 21 is of the type which directly senses the dynamic pressure in the extracted steam line 12 and produces a dynamic pressure signal.
However, the invention is not limited to this type of dynamic pressure detector and any other type of sensing means capable of producing as a dynamic pressure signal a signal indicating the dynamic pressure of the fluid in any form may be used. For example, an orifice may be formed in the exeracted steam line 12 and means for measuring the pressure differential QP' between the front and the rear of the orifice may be provided for producing an output signal associated with the pressure differential QP' as a dynamic pressure signal.
In this case, the pressure differential ~P' between the front and the rear of the orifice can be expressed as the product of the dynamic pressure (~2~/2g) and the pressure loss coefficient as in the case of the check valve expressed by equation (1). Since the pressure loss coefficient is constant, the differential pressure QP' is after all proportional to the dynamic pressure and can be used as a dynamic pressure signal. Besides, the flow rate of fluid through the extracted steam check vlave 13 or the load on the plant can be used as dynamic pressure signals because they are definably related to the dynamic pressure.
In the illustrated embodiment, the valve opening detector 22 is of the type that detects the 1153~1~
1 angle of rotation of the valve shaft 4. Generally, the valve disk of a swing-type check valve has a small angle of deviation (the degree of valve opening at full open position relative to that at full closed position) of 40 - 50. Thus, besides measuring the angle of rotation, the distance of movement (straight line dis-tance) on a chord may be detected and used as a valve opening signal.
The valve opening signal generated by the valve opening detector 22 and the dynamic pressure signal generated by the dynamic pressure detector 21 are supplied to the valve operating condition diagnosing apparatus 23 where the operating conditions of the extracted steam check valve 13 are diagnosed.
The valve operating condition diagnosing apparatus 23 may be in the form of a digital data processor which samples the valve opening signal and the dynamic pressure signal at suitable intervals of time and compares them with the data stored therein, to keep an eye on the operation of the check valve. More speci-fically, the data representing the normal operation of the check valve 13 which include the curves Al and A2 shown in Fig. 3 and representing the valve opening characteristics plus tolerances are stored as normal operation data, and the check valve 13 is ~udged as having normalcy or abnormality depending on whether or not the data obtained by actual measuring including the valve open-ing and the dynamic pressure actually measured at each sampling time are within the aforesaid tolerances.
'1153114 1 The diagnosis is carried on not only when the turbinesystem is in steady state operation but also when it is shut down or at startup. The diagnosis is usually carried out at a cycle of 0.2 to 10 seconds. However, at the time of steady state operation, the diagnosis may be performed at a cycle of longer duration, and when the extracted steam check valve 13 is suddenly closed as when the turbine is tripped, t,he diagnosis may be performed in a cycle of shorter duration of 0.01 to 0.1 second. The check valve 13 may be ~udged to have abnormality when the data obtained by actual measuring at a single sampling are not within the tolerances of the normal operation data stored. Alternatively, the ~udgement of abnormality may be passed only when the data obtained by actual measuring at a series of sampl-ing are not within the tolerances of the normal operation data stored.
The data representing the normal operation of the turbine stored in the turbine operating condition diagnosing apparatus 23 are first calculated from the valve opening characteristic design values and the desired tolerances, and the data obtained by actual measuring are compared with the stored data of normal operation at the time of trial operation of the plant and following disassembling and checking of the check valve at the time of periodic inspection, to judge whether or not the check valve is operating normally.
When the data obtained by actual measuring at the time 115;3114 1 the operation of the turbine is initiated are judged to ind~cate the presence o~ no abnormality in the check valve, such data are stored and characteristic curves based on the data obtained by actual measuring are prepared. The characteristic curves prepared in this way are used to correct the data of normal operation, so that the corrected data can be used in subsequent diagnosis as fresh normal operation data.
The method of diagnosis of the operating conditions of the check valve according to the invention will now be described in concrete terms by referring to Figs. 3 - 6. Fig. 4 shows the construction of the valve operating condition diagnosing apparatus 23 shown in Fig. 1. At initial stages of turbine plant operation, the design values of valve opening characteristics and tolerances therefor are fed into a normal operation data memory 31, to store the tolerances for the normal operation data. Then, at the time of the trial operation of the turbine plant, a dynamic pressure signal Poi from the dynamic pressure detector 21 and a valve opening signal VHi from the valve opening detector 22 shown in Fig. 1 are supplied at each of a series of diagnosing cycles to a ~udging unit 32, where the normal operation data transmitted from the normal operation data memory 31 are compared with the data obtained by actual measuring of the dynamic pressure signal and valve opening signal (Poi and VHi) to determine whether or not the latter are within the llS3~1~
1 tolerances for the normal operation data, to thereby judge the presence or absence of abnormality in the check valve 13. When the check valve 13 is judged to have abnormality, a signal is forwarded to a malfunc-tion indicator 35 to indicate the presence of malfunc-tion. Meanwhile when no malfunctions are found, the data obtained by actual measuring (Poi and VHi) are supplied from the ~udging unit 32 to a switch 33. At the time of the trial operation of the turbine plant, a selection signal of an ON position is supplied to the switch 33, so that the data obtained by actual measuring (Poi and VHi) are supplied via the switch 33 to a valve opening characteristi~s memory 34 and stored therein. When the data obtained by actual measuring and stored in the memory 34 exceed a predetermined level of number with respect to different dynamic pressures and actually measured valve opening characteristics are obtained, they are inputted to the normal operation data memory 31. At the same time, tolerances (input data) for the actually measured valve opening characteristics are also fed into normal operation data memory 31, so that the tolerances for the normal operation data determined previously based on the valve opening characteristic design values are corrected by the data obtained at the time of the actual operation of the turbine plant. The corrected normal operation data are stored as fresh normal opera-tion data. Thereafter, data obtained by actual measuring (Poi and VHi) are judged by the fresh normal operation llS31~4 1 data. Following the correction of the normal operation data stored in the normal operation data memory 31, the se:Lection signal is switched to an OFF position and the switch 33 no longer allows the data obtained by actual measuring to be supplied to the normal operation data memory 31.
When the data obtained by actual measuring (Po1 and VHi) are judged to indicate abnormality by the judging unit 32, the data (Poi and VHi) are supplied to a valve opening charactersitics memory 36 and stored therein. When the data obtained by actual measuring exceed a predetermined level of number with respect to different dynamic pressures, an abnormal valve opening characteristics are stored in the memory 36. Meanwhile a malfunction pattern memory 37 has stored therein abnormal valve opening characteristics (as represented by Bl, B2, C, D and E in Fig. 3, for example) due to different causes of malfunction. Thus the valve opening characteristics stored in the memory 36 are compared with the malfunction patterns stored in the malfunction pattern memory 37 at a malfunction cause ~udging unit 38, so that the cause of the malfunction is judged by the ~udging unit 38 and the ~udgment is indicated by a malfunction cause indicator 39.
Figs. 5 and 6 are flow charts showing data processing preformed by the valve operating condition diagnosing apparatus 23. The flow chart shown in 1153~1~
1 Fig. 5 deals with data processing for preparing normal operation data, wherein design values 102 for the valve opening characteristics and tolerances 103 for the design values 102 are fed into the apparatus 23 at initial stages 101 of turbine plant operation.
The design values of valve opening characteristics include a valve opening characteristic at the time of increasing dynamic pressure and a valve opening characteristic at the time of reducing dynamic pressure each represented by data of 5 to 10 points [each point is represented by (PO and VH) in which the dynamic pressure PO and the valve opening VH associated there-with form a set of data]~ The tolerances include a dynamic pressure tolerance QPO and a valve opening tolerance ~VH for accommodatlng variations with respect to each valve openlng characteristics data point (PO and VH), and the range of allowable variations for the valve opening data point is set at (PO + ~PO and VH ~ ~VH~. The data points are inter-polated by a straight line or smooth curve.
Allowable valve opening characteristicsessentially have two bands representing values deter-mined at the time of increasing dynamic pressure and at the time of reducing dynamic pressure respectively.
However, the hysteresis caused by frictional resistance tends to increase with time, so that the tolerances may be represented by one band as shown at 106 in Fig. 5.
Thus allowable valve opening characteristics 106 are .
' 1~L53~14 1 prepared in this way and registered as normal operation data as indicated at 107. When the turbine plant performs other operations than an initial stage opera-tion (mainly when a trial operation is performed), values representing the actual results of operation are inputted as indicated at 104 in place of the design values, and tolerances for the values representing the actual results of operation are also inputted as indicated at 105. These data are processed in the same manner as described hereinabove to obtain normal operation data.
~ he flow chart shown in Fig. 6 deals with the process for diagnosing the operating conditions of the check valve 13. Data obtained by actual measuring (Po1 and VHi) are fed into the diagnosing apparatus 23 as indicated at 111 each time sampling is carried out, and compared with the normal operation data obtained as described by referring to Flg. 5 as indicated at 112. When the data obtained by actual measuring are within the tolerances for the normal operation data, the check valve is judged to be operating normally;
and when they are not within the tolerances, the check valve is judged to have malfunction. When the check valve is ~udged to have malfunction as indicated at 113, a check valve malfunction warning is issued as indicated at 114 and at the same time a valve opening characteristic for the abnormal data is prepared as indicated at 115.
The valve opening characteristics for the malfunction .
1 data are compared with valve opening characteristics prepared beforehand for different causes of valve mal-functions, to determine the cause of the particular valve malfunction. When the data obtained by actual measuring are judged to indicate a normal operation of the check valve in the diagnosis of the operating conditions shown in Fig. 6, the next following sampling is performed. Particularly when a record of the valve opening characteristics for the normal operation of the check valve is made as indicated at 118 (input data give instructions on the need to prepare such record), data obtained by actual measuring are stored to provide valve opening characteristics as indicated at 119. When the turbine plant is operated as a trial operation, normal operation data are prepared based on the values representing the actual results of operation as described hereinabove by referring to Fig. 5.
In the embodiment shown and described herein-above, normal operation data including normal valve opening characteristics plus tolerances are prepared, and the presence or absence of abnormality in the check valve is ~udged by determining whether or not the data obtained by actual measuring are within the tolerances.
It is to be understood, however, that the invention is not limited to this specific form of the embodiment, and that various changes and modifications may be made therein. One example o~ such modifications will be 1~ 53114 1 described by referring to Fig. 3. In one modification, the normal valve opening characteristic curves Al and A2 are used as normal operation data, and the actually measured valve opening characteristic curves Bl and B2 are prepared as representing data obtained by actual measuring. The operating conditions of the check valve are judged as being normal or abnormal by comparing these curves with one another. In comparing the curves, the judgement on whether the operating conditions of the check valve are normal or abnormal is passed based on the following findings:
a. The spacing between curve Al of the normal data and curve Bl of the data obtained by actual measuring or the dynamic pressure differential at a predetermined valve opening, or the spacing therebetween or the valve opening differential at a predetermined dynamic pressure;
b. The difference in the gradient between the curves at a predetermined valve opening or a predeter-mined dynamic pressure; andc. The ratio of one hysteresis to another hysteresis in the data (the ratio of a dynamic pressure differential a to a dynamic pressure differential _ in Fig. 3) at a predetermined valve opening, or the corresponding ratio of hysteresis at a predetermined dynamic pressure.
From the forégoing description, it will be appreciated that the present invention enables the - 20 _ ~153~1~
1 operating conditions of a check valve to be automati-cally dlagnosed during operation, to determine whether or not there is abnormality in the check valve.
While preferred embodiments of the invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and modifications may be made therein without departing from the spirit - or scope of the following claims.
Claims (12)
1. A method of monitoring the operating conditions of a check valve mounted in a pipeline, comprising the steps of:
obtaining actual data by measuring a degree of opening of said check valve and a dynamic pressure of the flow of a fluid through the pipeline; and comparing in a judging unit the actual data with normal operation data stored beforehand in a memory, said normal operation data representing relations bet-ween degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating condi-tions of the check valve, whereby operating condition of the check valve can be monitored to determine whether or not the check valve has mulfunctions, said steps being carried out automatically.
obtaining actual data by measuring a degree of opening of said check valve and a dynamic pressure of the flow of a fluid through the pipeline; and comparing in a judging unit the actual data with normal operation data stored beforehand in a memory, said normal operation data representing relations bet-ween degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating condi-tions of the check valve, whereby operating condition of the check valve can be monitored to determine whether or not the check valve has mulfunctions, said steps being carried out automatically.
2. A method as set forth in claim 1, wherein said check valve is a swing-type check valve.
3. A method as set forth in claim 2, wherein said normal operation data indicate permitted region concerning the valve opening degrees and the dynamic pressures, said permitted region being obtained by calculation from valve opening characteristic design values and predetermined permitted limits, and the actual data is judged by the judging unit whether or not the actual data is within said permitted region, so as to determine whether or not the check valve has mulfunctions.
4. A method as set forth in claim 3, further comprising the step of correcting said normal operation data by the actual data which have been obtained at the time when the operation of the check valve was initiated and judged to be normal, to thereby obtain fresh normal operation data.
5. A method as set forth in claim 3, wherein said steps of obtaining actual data and comparing the actual data with the normal operation data are repeatedly per-formed in cycles at predetermined intervals of time, and said method further comprising the steps of storing those actual data which have been judged by the judging unit to be abnormal, in a second memory to obtain actually measured valve opening-dynamic pressure characteristic, and compar-ing the actually measured valve opening-dynamic pressure characteristic with a plurality of abnormal valve opening-dynamic pressure characteristics which have been stored in a third memory, corresponding to a plurality of causes for mulfunctions of the check valve, to thereby determine the cause of the mulfunctions of the check valve.
6. A method as set forth in claim 2, wherein said normal operation data stored in said memory comprise a normal valve opening-dynamic pressure characteristic curve calculated from valve opening-dynamic pressure character istic design values and said actual data comprise an actually measured valve opening-dynamic pressure characteristic curve drawn based on a plurality of valve opening signals and dynamic pressure signals produced at a plurality of sampling times, and wherein a gradient of the actually measured characteristic curve at one of a predetermined degree of valve opening and a predetermined dynamic pressure is compared with that of the normal characteristic curve, whereby an operating condition of the check valve is monitored to determine whether or not the check valve has mulfunctions.
7. A method as set forth in claim 6, further com-prising the step of correcting said normal operation data by the actual data obtained at the time when the operation of the check valve is initiated and judged to be normal, to thereby obtain fresh normal operation data.
8. A method as set forth in claim 2, wherein said operation data comprise normal hysteresis curves drawn based on valve opening-dynamic pressure characteristic design values and said actual data comprise actually measured hysteresis curves drawn based on a plurality of valve opening signals and dynamic pressure signals produced at a plurality of sampling times, and wherein a spacing between the actually measured hysteresis curves with regard to either a predetermined degree of valve opening or a predetermined dynamic pressure is com-pared with that of the normal hysteresis curves, whereby an operating condition of the check valve is monitored to deter-mine whether or not the check valve has mulfunctions.
9. A method as set forth in claim 8, further com-prising the step of correcting said normal operation data by the actual data obtained at the time when the operation of the check valve is initiated and judged to be normal, to thereby obtain fresh normal operation data.
10. An apparatus for monitoring the operating conditions of a swing-type check valve mounted in a pipeline, comprising first means for detecting the degree of opening of said check valve and producing a valve opening signal;
second means for detecting the dynamic pressure of the flow of a fluid upstream of said check valve and producing a dynamic pressure signal;
normal operation data memory for storing normal operation data representing relations between degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating conditions of the check valve; and a judging unit connected to said first means, second means and normal operation data memory to receive said valve opening signal, said dynamic pressure signal and said normal operation data, said judging unit function-ing to prepare actual data representing the relation between the detected degree of opening of the check valve and the detected dynamic pressure and to compare the actual data with said normal operation data, whereby the operating condition of the check valve is monitored to determine whether or not the check valve has mulfunctions.
second means for detecting the dynamic pressure of the flow of a fluid upstream of said check valve and producing a dynamic pressure signal;
normal operation data memory for storing normal operation data representing relations between degrees of opening of said check valve and dynamic pressures in the pipeline in the normal operating conditions of the check valve; and a judging unit connected to said first means, second means and normal operation data memory to receive said valve opening signal, said dynamic pressure signal and said normal operation data, said judging unit function-ing to prepare actual data representing the relation between the detected degree of opening of the check valve and the detected dynamic pressure and to compare the actual data with said normal operation data, whereby the operating condition of the check valve is monitored to determine whether or not the check valve has mulfunctions.
11. An apparatus as set forth in claim 10, further comprising means for repeatedly conducting monitoring operation at a predetermined time interval, and a second memory connected to said judging unit to receive and store therein those actual data which have been judged by said judging unit to be normal, said second memory being connected to said normal operation data memory to supply the actual data stored therein to the normal operation data memory, to thereby correct the normal operation data stored in the last-mentioned memory.
12. An apparatus as set forth in claim 11, further comprising a third memory connected to said judging unit to receive and store therein those actual data which have been judged by said judging unit to be abnormal, so that actually measured valve opening-dynamic pressure charac-teristic is stored in the third memory, a fourth memory for storing therein abnormal valve opening-dyanmic pressure characteristics which correspond to a plurality of causes for mulfunctions of the check valve, respectively, and a mulfunction cause judging unit connected to said third and fourth memory to receive the actually measured valve opening-dynamic pressure characteristic and the abnormal valve opening-dynamic pressure characteristics, and com-paring the actually measured characteristic with the abnormal characteristics, to thereby judge the cause of the malfunctions of the check valve.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP152044/1979 | 1979-11-26 | ||
| JP15204479A JPS5676767A (en) | 1979-11-26 | 1979-11-26 | Detecting method for abnormality in swing-type nonreturn valve |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153114A true CA1153114A (en) | 1983-08-30 |
Family
ID=15531823
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000365334A Expired CA1153114A (en) | 1979-11-26 | 1980-11-24 | Method of sensing malfunctions of check valve mounted in pipeline and apparatus therefor |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5676767A (en) |
| AU (1) | AU526510B2 (en) |
| CA (1) | CA1153114A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4777979A (en) * | 1987-11-16 | 1988-10-18 | Westinghouse Electric Corp. | Position detector for clapper of non-return valve |
| US4805665A (en) * | 1988-01-04 | 1989-02-21 | League Billy E | Fluid flow check device |
| US5115672A (en) * | 1991-02-11 | 1992-05-26 | Westinghouse Electric Corp. | System and method for valve monitoring using pipe-mounted ultrasonic transducers |
| US5154080A (en) * | 1986-10-29 | 1992-10-13 | Westinghouse Electric Corp. | Integrated check valve testing system |
| CN119163805A (en) * | 2024-11-20 | 2024-12-20 | 中国空气动力研究与发展中心低速空气动力研究所 | Pressure scanning valve state monitoring method, device and equipment |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008115891A (en) * | 2006-10-31 | 2008-05-22 | Inax Corp | Hot water-water mixing valve |
| CN107782560A (en) * | 2017-11-20 | 2018-03-09 | 潍柴动力股份有限公司 | A kind of bypass type booster fault detection method and device |
| CN108680347B (en) * | 2018-05-14 | 2020-03-24 | 中广核研究院有限公司 | Valve flow characteristic identification method in impurity environment |
| CN110887658A (en) * | 2018-09-05 | 2020-03-17 | 东泰高科装备科技（北京）有限公司 | Gas safety loop control method |
| CN114607505B (en) * | 2022-03-01 | 2023-03-21 | 潍柴动力股份有限公司 | An engine supercharger fault detection method, detection device and detection equipment |
-
1979
- 1979-11-26 JP JP15204479A patent/JPS5676767A/en active Granted
-
1980
- 1980-11-24 CA CA000365334A patent/CA1153114A/en not_active Expired
- 1980-11-24 AU AU64628/80A patent/AU526510B2/en not_active Ceased
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5154080A (en) * | 1986-10-29 | 1992-10-13 | Westinghouse Electric Corp. | Integrated check valve testing system |
| US4777979A (en) * | 1987-11-16 | 1988-10-18 | Westinghouse Electric Corp. | Position detector for clapper of non-return valve |
| US4805665A (en) * | 1988-01-04 | 1989-02-21 | League Billy E | Fluid flow check device |
| US5115672A (en) * | 1991-02-11 | 1992-05-26 | Westinghouse Electric Corp. | System and method for valve monitoring using pipe-mounted ultrasonic transducers |
| CN119163805A (en) * | 2024-11-20 | 2024-12-20 | 中国空气动力研究与发展中心低速空气动力研究所 | Pressure scanning valve state monitoring method, device and equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6462880A (en) | 1981-07-02 |
| JPS5740942B2 (en) | 1982-08-31 |
| JPS5676767A (en) | 1981-06-24 |
| AU526510B2 (en) | 1983-01-13 |
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