A predictive maintenance diagnosis method for a pneumatic on-off valve

Abstract

The present application relates to a kind of pneumatic switch valve predictive maintenance diagnosis method, including several pneumatic switch valves, the valve back switch for detecting the switch position of each described pneumatic switch valve, for controlling and detecting each described pneumatic switch valve Control system, the solenoid valve of the switch of the described pneumatic switch valve, the maintenance diagnosis method of each described pneumatic switch valve in the control system includes S1: determine the pneumatic switch valve to be detected;S2: in control system, set and input the numerical value of predictive diagnosis;S3: numerical value is compared and calculated by controller and carries out alarm count.Thereby the purpose of predictive maintenance diagnosis is completed.The method is simple in operation, high in efficiency, reduce cost, improve safety.

Description

Technical Field

[0001] This invention relates to the field of valve maintenance technology, and specifically to a predictive maintenance and diagnostic method for pneumatic on / off valves. Background Technology

[0002] In large and medium-sized continuous chemical production plants, regular maintenance of pneumatic switching valves is crucial for the stable operation of the unit. However, due to the large number of pneumatic switching valves, partial maintenance may leave some valves with unresolved issues. When these valves malfunction and fail to operate, it can lead to partial or complete plant shutdowns, or even safety accidents. Complete offline maintenance is time-consuming and costly.

[0003] The main causes of pneumatic switching valve failure are: a) Frequent operation of the pneumatic actuator causes wear and loosening of various seals, leading to air leakage and external contamination, resulting in slow, incomplete, or no operation of the pneumatic switching valve; b) The valve core may become stuck or detach from the valve stem due to various reasons, causing slow, accelerated, incomplete, or no operation of the pneumatic switching valve; c) Solenoid valve malfunction causes the pneumatic switching valve to not operate; d) Fluctuations in the instrument air pressure of the pneumatic switching valve cause slow, incomplete, or no operation. Based on the above analysis of the causes of pneumatic switching valve failure, incomplete or no valve operation can be easily determined by the valve feedback switch, which is an explicit failure. However, slow valve operation does not affect the normal operation of the process and is generally difficult to detect, which is a latent failure. Identifying latent failures is essentially prediction. When latent failures are not detected in time, over time, they can easily lead to valve malfunction or incomplete operation, causing the device to stop or causing an accident, posing a safety hazard. This invention addresses these problems with innovative improvements. Summary of the Invention

[0004] To overcome the aforementioned shortcomings of the prior art, this invention proposes a predictive maintenance and diagnostic method for pneumatic switching valves that is easy to use, can promptly detect hidden valve faults, and improves safety.

[0005] The specific implementation scheme of the present invention is as follows:

[0006] This application provides a predictive maintenance and diagnostic method for pneumatic switching valves, including a valve feedback switch for detecting the switching position of each pneumatic switching valve, a control system for controlling and detecting each pneumatic switching valve, and a solenoid valve for controlling the switching of the pneumatic switching valves. The method for maintenance and diagnostics of each pneumatic switching valve by the control system includes:

[0007] S1: Determine the pneumatic switching valves that need to be monitored, and set the opening and closing times of each pneumatic switching valve through the control system. The reference time for the normal opening action of each pneumatic switching valve is t. 开参考 The reference time for the closing action is t. 关参考 ;

[0008] S2: The control system presets the alarm values ​​for the opening / closing action time of the pneumatic switch valve that needs to be monitored. The preset opening and closing action times of the pneumatic switch valve are t and t, respectively. 开设 and t 关设 ;

[0009] S3: Calculate the actual valve opening / closing time for each of the pneumatic switching valves, where the opening time of each pneumatic switching valve is t. 开 The closing time of the pneumatic switching valve is t. 关 Then, the control system controls the t of each of the pneumatic switching valves. 开 and t 开参考 Compare, t 关 and t 关参考 Compare the results, calculate the differences separately, and denot them as t. 开比较 and t 关比较 When t 开比较 Greater than the preset alarm value t 开设 time or t 关比较 Greater than the preset alarm value t 关设 When an alarm is triggered, the control system issues an alarm and counts the alarms. By analyzing the alarms and alarm counts, it determines whether a valve has malfunctioned, thereby achieving the purpose of predictive maintenance.

[0010] Preferably, the control system includes an I / O card, a controller, and an operator station. The I / O card includes a digital input card responsible for receiving the feedback switch signal from the pneumatic switch valve and converting it into a digital input signal that the control system can receive, and a digital output card that converts the instructions issued by the controller into digital output signals to the solenoid valve. The digital input card is connected to the valve feedback switch and transmits the digital input signal to the controller. The controller processes the received digital input signal through the communication network within the control system and feeds it back to the operator station.

[0011] Preferably, the controller includes a counter for alarm counting, a comparator for difference comparison, a timer and a trigger for receiving the actual valve opening / closing time of the pneumatic switch valve, and valve control logic for controlling the opening and closing of the pneumatic switch valve. The valve control logic is connected to a digital input card. The valve control logic and the digital input card respectively transmit signals to the trigger, and the trigger transmits signals to the timer. After the timer counts, it transmits the actual valve opening / closing time to the comparator. The comparator compares and calculates the values ​​set in it, and then transmits the calculation result to the counter for alarm counting and displays the alarm count on the operator station.

[0012] Preferably, the valve feedback switch includes a valve open feedback switch and a valve close feedback switch. There are two digital input cards, two triggers, two timers, and two counters. The digital input cards are connected to the valve open feedback switch and the valve close feedback switch, respectively. The valve open feedback switch and the valve close feedback switch send valve open feedback signals and valve close feedback signals to the triggers, respectively. The triggers are connected to the timers, and the timers are connected to the counters.

[0013] Preferably, the operating station includes a display, which is used to display the actual opening / closing time of each pneumatic switch valve action, the alarm count of the pneumatic switch valve opening / closing action, and the setting and display of the reference time and preset time for the pneumatic switch valve opening / closing action.

[0014] Preferably: t of S2 开设 and t 关设 The preset time is 2-10 seconds.

[0015] Preferably, the control system is a DCS system or a PLC system.

[0016] Beneficial effects:

[0017] 1. No new equipment is required, and there is no fixed asset investment.

[0018] 2. This method is simple and highly practical.

[0019] 3. It can be extended to the diagnostics of predictive maintenance of pneumatic switching valves in continuous production chemical plants, reducing production and safety accidents caused by potential faults in pneumatic switching valves, overcoming blind maintenance, reducing maintenance time, improving equipment reliability and availability, and lowering maintenance costs.

[0020] The beneficial effects of the present invention will be described in detail in the embodiments, thereby making the beneficial effects more obvious. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system structure in a specific embodiment of the present invention.

[0022] in:

[0023] 1. Pneumatic switching valve; 2. Solenoid valve; 3. Valve closing feedback switch; 4. Valve opening feedback switch; 5. I / O card; 51. Digital input card; 52. Digital output card; 6. Controller; 61. Valve control logic; 62. Trigger; 63. Timer; 64. Comparator; 65. Counter; 7. Operator station; 71. Display. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0025] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0026] The embodiments of this application will be described in detail below with reference to the accompanying drawings and specific examples and application scenarios.

[0027] Example 1

[0028] like Figure 1 As shown, a predictive maintenance and diagnostic method for pneumatic switching valves includes several pneumatic switching valves 1, and a method for using...

[0029] The system includes a valve feedback switch for detecting the on / off position of each of the pneumatic switching valves 1, a control system for controlling and detecting each of the pneumatic switching valves 1, and a solenoid valve 2 for controlling the on / off state of the pneumatic switching valves 1. In a specific embodiment of the invention, the maintenance and diagnostic method for each of the pneumatic switching valves 1 by the control system includes:

[0030] S1: Determine the pneumatic switching valve 1 that needs to be monitored, and set the opening and closing times of each pneumatic switching valve 1 through the control system. The reference time for the normal opening action of each pneumatic switching valve 1 is t. 开参考 The reference time for the closing action is t. 关参考 ;

[0031] S2: The control system presets the alarm values ​​for the opening / closing action time of the pneumatic switch valve 1 that needs to be monitored. The preset opening and closing action times of the pneumatic switch valve 1 are t and t, respectively. 开设 and t 关设 ;

[0032] S3: Calculate the actual opening / closing time of each of the pneumatic switching valves 1, wherein the opening time of each pneumatic switching valve 1 is t. 开 The closing time of the pneumatic switching valve 1 is t. 关 Then, the control system controls the t of each of the pneumatic switching valves 1. 开 and t 开参考 Compare, t 关 and t 关参考 Compare the results, calculate the differences separately, and denot them as t. 开比较 and t 关比较 When t 开比较 Greater than the preset alarm value t 开设 time or t 关 The comparison is greater than the preset alarm value t 关设 When an alarm is triggered, the control system issues an alarm and counts the alarms. By analyzing the alarms and alarm counts, it determines whether a valve has malfunctioned, thereby achieving the purpose of predictive maintenance.

[0033] First, input the reference time for the normal opening and closing action of pneumatic switch valve 1 into the control system, and record it as t. 开参考 and t 关参考 Then, the alarm values ​​for the preset switch actions are t. 开设 and t 关设 During operation, the pneumatic switch valve 1 is opened and closed by solenoid valve 2. When the valve opens or closes, a switch signal is transmitted to the control system via a valve feedback switch. The control system records the actual opening and closing time of the pneumatic switch valve 1, denoted as t. 开 and t 关 Then the control system performs calculations, as shown in Table 1, t 开 -t 开参考 =t 开比较 , t 关 -t 关参考 =t 关比较 When t 开比较 Greater than t 开设 or t关比较 Greater than t 关设 If the valve shows a delay, it indicates a lag; otherwise, it's normal. The control system then feeds back the signal of the lag and issues an alarm, while simultaneously accumulating a count of the lag occurrences, known as the alarm count. Operators use the alarm count to determine if pneumatic switch valve 1 is functioning correctly. For example, a count of one might be due to error or coincidence, and continued observation is sufficient. No cumulative count can be ignored. However, if there are more than one, or even three or four, attention is needed, indicating a high frequency of malfunctions in pneumatic switch valve 1. The equipment should be stopped for maintenance of pneumatic switch valve 1. This achieves predictive maintenance, reduces maintenance time, prevents unnecessary repairs or proactive checks, improves equipment reliability and availability, reduces maintenance costs, and ensures production safety.

[0034] The t of S2 开设 and t 关设 The preset time is 2-10 seconds, which can be adjusted according to the actual valve diameter, type and operating conditions. Generally, it is adjustable from 2 to 10 seconds. Setting it too high will cause the fault to be undetected, while setting it too low will cause frequent alarms, resulting in frequent maintenance but sometimes there may be no fault. Therefore, the adjustable range of 2-10 seconds can overcome the blindness of maintenance, make each maintenance more targeted, and improve work efficiency.

[0035] Table 1

[0036] KV-16111A (Open) 8 2 9 normal 0 KV-16111A (Offshore) 11 3 15 Call the police 2

[0037] As can be seen from Table 1,

[0038] When t 开比较 =1,t 开设 When t = 2, at this time t 开比较 <t 开设 If the count is 0, it is considered normal, there will be no alarm, and the counter will display as 0.

[0039] When t 关比较 =4,t 关设 When t = 3, at this time t 关比较 >t 关设 If the count is 1 or higher, it indicates an abnormality, triggering an alarm.

[0040] Example 2

[0041] The improvement based on Example 1 is as follows: Figure 1As shown, the control system includes an I / O card 5, a controller 6, and an operator station 7. The I / O card 5 includes a digital input card 51 responsible for receiving the digital signal of the opening / closing action time of the pneumatic valve and converting it into a digital input signal that the control system can receive, and a digital output card 52 that converts the instructions issued by the controller 6 into digital output signals to the solenoid valve 2. The digital input card 51 is connected to the valve feedback switch and transmits the digital input signal to the controller 6. The controller 6 processes the received digital input signal through the communication network within the control system and feeds it back to the operator station 7.

[0042] When the digital output card 52 sends the command from the controller 6 to the solenoid valve 2, the solenoid valve 2 opens or closes the pneumatic switch valve 1. Then, the open / close signal of the pneumatic switch valve 1 is transmitted to the digital input card 51 through the valve feedback switch. The valve feedback switch includes a valve open feedback switch 4 and a valve close feedback switch 3. There are two digital input cards 51, triggers 62, timers 63, and counters 65. The digital input card 51 is connected to the valve open feedback switch 4 and the valve close feedback switch 3 respectively. The valve open feedback switch 4 and the valve close feedback switch 3 send the valve open feedback signal and the valve close feedback signal to the trigger 62 respectively. The trigger 62 is connected to the timer 63 respectively. The timer 63 is connected to the counter 65 respectively. After the digital input card 51 converts and processes the signal into a digital input signal, it sends it to the controller 6. Then, following the steps set in Embodiment 1, the received digital input signal is processed through the communication network in the control system and fed back to the operator station 7. The operation station 7 includes a display 71, which is used to display the actual opening / closing time of each pneumatic switch valve 1, the alarm count of the opening / closing action of the pneumatic switch valve 1, and the setting and display of the reference time and preset time for the opening / closing action of the pneumatic switch valve 1, so as to facilitate the operator to set values ​​and view them, and to detect problems in a timely manner.

[0043] The controller 6 includes a counter 65 for alarm counting, a comparator 64 for difference comparison, a timer 63 and a trigger 62 for receiving the actual valve opening / closing time of the pneumatic switch valve 1, and valve control logic 61 for controlling the opening and closing of the pneumatic switch valve 1. The valve control logic 61 is connected to a digital input card 52. The valve control logic 61 and the digital input card 51 respectively transmit signals to the trigger 62, and the trigger 62 transmits signals to the timer 63. After the timer 63 counts, it transmits the actual valve opening and closing time to the comparator 64. The comparator 64 compares and calculates the values ​​set in the comparator 64, and the comparator 64 transmits the calculation result to the counter 65 for alarm counting and then displays the alarm count on the operator station 7.

[0044] Valve control logic 61 is a separate program for controlling the valve, which is existing technology. It is used to control the opening and closing of solenoid valve 2. Valve control logic 61 transmits signals to digital output card 52 to complete the opening and closing of solenoid valve 2. Digital output card 52 converts the signals from logic controller 6 into digital output signals that solenoid valve 2 can receive to start or close solenoid valve 2. Valve control logic 61 is connected to two triggers 62. Digital input card 51 transmits digital input signals to triggers 62 respectively. Triggers 62 are RS triggers. The output signals of triggers 62 are used to start and stop timer 63. Timer 63 is started when S=1 and stopped when S=0. Then, after timer 63 counts, the actual valve opening and closing time is transmitted to comparator 64. (The t in embodiment 1...) 开参考 t 关参考 t 开设 t 关设 The value is input into the comparator 64 beforehand via the display 71, and then the actual switching action time t is counted by the timer 63. 开 t 关 Compare with t in comparator 64 respectively 开参考 t 关参考 Perform the difference calculation and output the resulting difference t. 开比较 and t 关比较 With t 开设 and t 关设 The system compares the data to determine if the pneumatic switch valve 1 is malfunctioning and sends the result to the counter 65 for alarm counting. Then, the actual opening / closing time of each pneumatic switch valve 1 action, the alarm count for each opening / closing action, and the reference time for each opening / closing action are displayed on the monitor 71 of the operator station 7. This allows operators to easily observe and perform timely maintenance, saving time and effort. It eliminates the need for new equipment; improvements are made directly to the existing equipment, thus reducing costs.

[0045] Example 3

[0046] Further improvements can be made to any of the above embodiments, such as... Figure 1 As shown, the control system is either a DCS system or a PLC system, preferably a DCS system. A DCS system is a fully functional, open system using network communication technology, offering high reliability, comprehensiveness, and specialization. It enables human-machine interaction, has good scalability, strong management capabilities, and features centralized management and distributed control. Compared to a PLC system, it requires less debugging work and is easier to maintain later.

[0047] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0048] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A predictive maintenance and diagnostic method for pneumatic switching valves, comprising a plurality of pneumatic switching valves, a valve feedback switch for detecting the switching position of each of the pneumatic switching valves, a control system for controlling and detecting each of the pneumatic switching valves, and a solenoid valve for controlling the switching of the pneumatic switching valves, characterized in that: The maintenance and diagnostic methods for each of the pneumatic switching valves in the control system include: S1: Determine the pneumatic switching valves that need to be monitored, and set the opening and closing times of each pneumatic switching valve through the control system. The reference time for the normal opening action of each pneumatic switching valve is t. 开参考 The reference time for the closing action is t. 关参考 ; S2: The control system presets the alarm values ​​for the opening / closing action time of the pneumatic switch valve that needs to be monitored. The preset opening and closing action times of the pneumatic switch valve are t and t, respectively. 开设 and t 关设 ; S3: Calculate the actual valve opening / closing time for each of the pneumatic switching valves, where the opening time of each pneumatic switching valve is t. 开 The closing time of the pneumatic switching valve is t. 关 Then, the control system controls the t of each of the pneumatic switching valves. 开 and t 开参考 Compare, t 关 and t 关参考 Compare the results, calculate the differences separately, and denot them as t. 开比较 and t 关比较 When t 开比较 Greater than the preset alarm value t 开设 time or t 关比较 Greater than the preset alarm value t 关设 When an alarm occurs, the control system issues an alarm and counts the alarms. The alarms and alarm counts are used to determine whether the valve has malfunctioned, thereby achieving the purpose of predictive maintenance. The control system feeds back signals indicating a delay in valve operation and accumulates the count, i.e., alarm count. When the error in the number of alarm counts exceeds one, the equipment needs to be stopped for maintenance of the pneumatic switch valve.

2. The predictive maintenance and diagnostic method for a pneumatic switching valve according to claim 1, characterized in that: The control system includes an I / O card, a controller, and an operator station. The I / O card includes a digital input card that receives the feedback switch signal from the pneumatic switch valve and converts it into a digital input signal that the control system can receive, and a digital output card that converts the instructions issued by the controller into digital output signals to the solenoid valve. The digital input card is connected to the valve feedback switch and transmits the digital input signal to the controller. The controller processes the received digital input signal through the communication network within the control system and feeds it back to the operator station.

3. The predictive maintenance and diagnostic method for a pneumatic switching valve according to claim 2, characterized in that: The controller includes a counter for alarm counting, a comparator for difference comparison, a timer and a trigger for receiving the actual valve opening / closing time of the pneumatic switch valve, and valve control logic for controlling the opening and closing of the pneumatic switch valve. The valve control logic is connected to a digital input card. The valve control logic and the digital input card respectively transmit signals to the trigger, and the trigger transmits signals to the timer. After the timer counts, it transmits the actual valve opening / closing time to the comparator. The comparator compares and calculates the values ​​set in it, and then transmits the calculation result to the counter for alarm counting. Finally, the alarm count is displayed on the operator station.

4. The predictive maintenance and diagnostic method for a pneumatic switching valve according to claim 3, characterized in that: The valve feedback switch includes a valve open feedback switch and a valve close feedback switch. There are two digital input cards, two triggers, two timers, and two counters. The digital input cards are connected to the valve open feedback switch and the valve close feedback switch, respectively. The valve open feedback switch and the valve close feedback switch send the valve open feedback signal and the valve close feedback signal to the trigger, respectively. The triggers are connected to the timers, and the timers are connected to the counters.

5. The predictive maintenance and diagnostic method for a pneumatic switching valve according to claim 4, characterized in that: The operating station includes a display, which is used to display the actual opening / closing time of each pneumatic switch valve action, the alarm count of the pneumatic switch valve opening / closing action, and the setting and display of the reference time and preset time for the pneumatic switch valve opening / closing action.

6. The predictive maintenance and diagnostic method for a pneumatic switching valve according to claim 1, characterized in that: The t of S2 开设 and t 关设 The preset time is 2-10 seconds.

7. A predictive maintenance and diagnostic method for a pneumatic switching valve according to any one of claims 1-6, characterized in that: The control system is a DCS system or a PLC system.

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