In recent years, in order to improve the modernization level of equipment management and maintenance, with the support and assistance of the Provincial Institute of Oil and Gas Equipment Division, our factory has applied condition monitoring and fault diagnosis technology to detect and solve many hidden equipment problems and improve equipment operation. The reliability has laid a good foundation for the long-term and full-load production of the power plant.
1 The reason for conducting condition monitoring and fault diagnosis
1.1 Condition Monitoring and Troubleshooting is a New Management Concept
Power plant production is characterized by a high level of automation and strong production continuity. Once a unit fails, it will force the unit to reduce its load and even shut down. Years of beatings and tempering tell us that judging the equipment failures by seeing, touching, hearing, and sniffing can no longer meet the requirements of modern production. Only by performing condition monitoring and troubleshooting can we completely get rid of this. Backward management model.
1.2 Condition Monitoring and Fault Diagnosis Are Needs to Improve Equipment Management Level
Our factory has carried out 8 major repairs. Although the targeted and directional properties have been greatly improved in the establishment of overhaul projects and the replacement of equipment system components, there are still gaps between exactness, suitability, and economy. According to the spirit of the "four commons," the standard requirements for equipment and systems should be more scientific and targeted, and blindness should be reduced. To solve this problem, only state monitoring and fault diagnosis should be carried out.
1.3 Condition monitoring and fault diagnosis are needed to reduce costs and increase efficiency. The cost of repairs in our factory is tightening year-by-year, and the pressure for cost reduction and efficiency increase is increasing year by year. How to further reduce the cost of power generation is a real issue facing the cadres of the whole plant. Judging from the overhaul situation over the years, some units have different degrees of overhaul and overhaul. Excess maintenance means that the workload is increased, the cost is increased, and the human, financial and material waste is caused, and the lack of repair will bring hidden troubles to the operation of the equipment. To carry out condition monitoring and fault diagnosis can effectively avoid unsatisfactory maintenance and overhaul, so as to make the best use and achieve the purpose of cost reduction and efficiency increase.
1.4 Condition monitoring and fault diagnosis are needed in the second phase of production
The two units of the second phase of our plant have been put into operation one after another. If we follow the plans for major repairs in the past three years, we must arrange at least one unit overhaul each year, and even schedule the overhaul of two units in one year. After 8 times of overhaul of the unit, our factory has accumulated rich experience in maintenance and has a deeper understanding of the performance characteristics of equipment and systems. In particular, the technical modification overhaul of the unit in 1999 and 2000 has significantly improved the reliability of the equipment, and basically provided conditions for revising the unit from three years to one year to four years of major repairs. The guarantee for extending the overhaul period is to carry out condition monitoring and fault diagnosis to prolong the service life of equipment and avoid sudden failures.
In recent years, through practice, the understanding of condition monitoring and fault diagnosis has been gradually improved. Through the timing, fixed-point, and fixed-person monitoring of the equipment, especially the on-line monitoring system of Unit #2, multiple equipment accidents have been avoided, which has strengthened us. The determination to carry out this work.
2 The basis for developing condition monitoring and fault diagnosis techniques
2.1 The meaning of status monitoring and fault diagnosis technology
Equipment condition monitoring usually refers to checking whether a device's status is normal by measuring a characteristic parameter of the equipment (such as vibration and temperature). When the characteristic parameter is less than the allowable value, it is considered normal, otherwise it is considered abnormal. The equipment fault diagnosis technology is to know, grasp the status of the online use of the equipment, combine the operating history of the equipment, predict, analyze and judge the faults that may occur or have occurred, and determine the nature, type, degree, and cause of the fault. Parts, indicating the occurrence and development of faults and their consequences, suggesting measures to control the continued development of faults, and eliminating the faults by adopting measures for adjustment, maintenance, and management, and eventually returning the equipment to its normal state.
At present, the equipment condition monitoring and fault diagnosis technology is an important part of modern equipment management and is an indispensable means for equipment management and maintenance management. Especially in today's increasingly fierce market competition, the maintenance and reduction of equipment maintenance costs is one of the most tappable potential for companies. Therefore, the application of condition monitoring and fault diagnosis techniques makes it a historical necessity that predictive maintenance replaces traditional and backward maintenance and regular preventive maintenance.
2.2 Implementing and Enforcing the "Equipment Management Regulations for Ownership-Owned Industrial Transport Enterprises"
Regulations on the Administration of Equipment for All-Urban-owned Industrial Transportation Enterprises. Article 7 of the "Regulations" stipulates: "Enterprises shall actively adopt advanced equipment management methods and maintenance techniques, adopt equipment maintenance methods based on condition monitoring, and continuously improve the modernization level of equipment management and maintenance technology." This provision indicates the direction for enterprises to carry out monitoring of equipment status, so that the leaders and employees of the company clearly define the status and role of condition monitoring technology in the actual equipment management.
The deepening and improvement of the state monitoring work has made us realize that the transition from the planned maintenance system to the state maintenance system is a fundamental reform of the equipment maintenance system and method, and is a concrete embodiment of the idea of ​​seeking truth from facts in the maintenance work. In the reform of the maintenance system, profound changes will take place in the status and role of the staff. They will become passive decision-makers in equipment maintenance from the mere passive maintenance of equipment. The state maintenance system is based on accurate condition monitoring and fault diagnosis, especially real-time online monitoring. The quality of status monitoring work will be related to whether it can be transferred from planned maintenance to status maintenance, the speed of conversion, and the degree of conversion.
3 Status of our plant condition monitoring
3.1 Offline Monitoring
Status Monitoring The major off-line instruments currently available are multifunction data collectors and their supporting software, infrared thermal imagers and their supporting software, vacuum leak detectors and bearing stethoscopes. On-line monitoring of large-scale key auxiliary equipment of Unit #2 has been installed. In the system, various monitoring and monitoring equipment such as vibrometers, spot thermometers, tachometers and other advanced monitoring equipments are all equipped for the operation and maintenance team.
According to the principle of equipment inspection and division of labor, testing points for equipment are set up with inspection cycle, inspection standards and inspection routes; data images from the inspection are analyzed and a monitoring report is issued; in addition to the equipment in question, the related professional is notified in a timely manner. In addition, detailed text descriptions are provided on the standard format exception reports; equipment that should receive attention is shortened in terms of monitoring cycles, and continuous follow-up monitoring is conducted so that early detection and early processing can be conducted to prevent accidents from expanding.
In addition, before the large and minor repairs of the unit, it is generally required to conduct a comprehensive inspection once to provide a reference for the overhaul of the equipment, and to conduct a comprehensive inspection once more to facilitate a comprehensive evaluation of the quality of maintenance. If there are any problems during the start-up of the unit, follow-up monitoring is also required to ensure the safety of the unit.
3.2 Online monitoring
State-based maintenance requests promptly inspect maintenance requests before unit equipment failures, avoid fault shutdowns and unnecessary load disturbances, and maximize the unit's operational reliability. Obviously, condition maintenance requires continuous tracking and analysis of the performance parameters and operating conditions of the unit equipment. The #2 unit has installed a real-time online monitoring system to track and analyze the status of the equipment.
3.3 Strengthen training and continuously improve monitoring
The popularity, depth, and improvement of the monitoring of equipment status is critical to the quality of personnel. Our factory attaches great importance to the training of condition monitoring technicians, and uses various methods such as workshops in the factory, off-site learning, and going in and out, constantly improving the quality and business level of the monitoring personnel. For example, in the process of handling #1 generator vibration in 1999, the training center seized the opportunity to hold a vibration lecture throughout the factory, and asked the senior engineer of the Xi'an Thermal Engineering Institute to give lectures. Shi Gaogong did not give any profound theory when he taught on September 11th, 1999. The central content of the problem is the diagnosis and diagnostic methods. The correctness of diagnostic ideas and the correctness of diagnostic methods will directly affect the accuracy of diagnosis. This training has greatly benefited the diagnostic personnel and brought their diagnostics to a new level.
In order to adapt to the needs of the new two units, the plant reconstructed the original coal conveying system in 2002. The #6 belt was equipped with a new motor and the vibration during the trial operation was as high as 230 μm. The construction unit and the motor purchase unit each insisted. Through tests, the harmonic energy is concentrated on the fundamental frequency, which is a typical feature of the rotor imbalance, but the diagnosis personnel did not make premature conclusions. Instead, according to the diagnostic ideas and methods, the dynamic stiffness of the motor foundation was first examined. Found that the horn between the motor and the foundation is not flat, the wrong position, resulting in insufficient connection rigidity; the motor base is a steel frame welded structure, its support stiffness is seriously insufficient, in order to prove this, the motor is placed on the ground trial operation, The measured vibration is only 12 μm. Therefore, it is no problem to diagnose the newly purchased motor itself, and the dynamic stiffness of the motor base is seriously insufficient, and measures should be taken to reinforce the foundation. After the construction unit grinds the motor base, the vibration of the motor is reduced to less than 20μm.
In August 2003, during the annual audit of marine equipment, the Authority detected that the vibration of the shipbuilding company's 151-ship #2 diesel generator was as high as 287 μm. Although the harmonic energy was concentrated in the fundamental frequency, the diagnosticians used the forward inference method quickly and accurately. Locking the dominant failure to the lack of foundation dynamic stiffness solves a production problem for the shipping company.
4 Effect of Application Status Monitoring and Fault Diagnosis Technology
Incomplete statistics based on work records So far, the State Monitoring and Fault Diagnosis Office has discovered 182 hidden troubles in field equipment, which undoubtedly played an important role in our factory's safe production and avoiding direct or indirect economic losses.
1, on-site dynamic balance vacuum system leak detection
According to incomplete statistics, since 1998, the company has used the data collector to carry out on-site dynamic balancing for 107 times. The steam turbine vacuum system has leaked 28 times and found many leakage points. The maintenance personnel have handled the shutdown according to the leakage degree and repaired the size and size. . This not only prolongs the service life of the equipment, but also drastically changes the practice of asking people to do dynamic balancing and leak checking in the past, saving 1,200,000 yuan for our factory.
2, bearing failure
According to statistics, a total of 32 bearing failures have been detected since 1998, and tracking and monitoring and symptomatic remediation have all greatly extended the bearing life. Among them, there are two serious bearing failures, and we still remember them so far. From February to April 2001, the operation status of the suction fan of unit #1 was extremely unstable, and the axial vibration of the free-end bearing oscillated within 40 to 180 μm. After frequency analysis, combined with the phase test and ferro-iron spectrum analysis, it was determined that The inner ring of the bearing was loose. During the inspection, the journal was found to be heavily worn. After repair, the vibration was only 50 μm. In July 2002, after the maintenance of the #1 unit suction fan was planned, the vibration in the vertical and horizontal directions of the bearing seat was less than 30 μm. The vibration was as high as 204 μm, and it was extremely unstable. The fault diagnosis personnel used the forward reasoning method to find out where the fault was. After replacing the deflected bearing, the vibration was reduced to less than 20 μm so that the fan could resume operation in time.
3, electrical failure
According to statistics, in recent years, a total of 43 hidden troubles in electrical areas have been discovered, providing a basis for leadership decisions. On July 27, 1998, when a fault detector used an infrared thermal imager to perform a routine inspection of the equipment, it was found that the maximum temperature of the A-phase bushing of the #1 main transformer 110KV at the general cap was 62.1°C, and the temperature difference with the phase B was 26.4°C. An emergency power-off repair was performed. The dismantling inspection revealed that more than 30 lines of A-phase cable-breaking cords were broken, and the fault was severely overheated. The cable-wrapped cords had been severely blackened, and the oily carbonization was severe. A major accident was avoided; On the 22nd of the month, the temperature of the top of the #1 main casing of the A-phase main casing was found to be as high as 108.6°C, and the maximum temperature was raised as 80.6°C. The difference in temperature from the same point as B and C was 55.6°C. After disassembling inspection, it was confirmed that the lead copper screw had undergone severe discoloration.
The discovery and elimination of these hidden dangers has brought incalculable economic benefits to our factory. However, this has undoubtedly played a positive role in the process of the establishment of a standard power plant and a first-class power plant in our factory. It is a period safety and economy for our plant managers. The stable operation has made significant contributions.
5 Concluding remarks
The use of condition monitoring and fault diagnosis technology can facilitate, quickly and effectively grasp the operation status of the equipment, eliminate the faults in the bud, improve equipment maintenance, and promote safe production. Although our factory has accumulated certain experience in this area, but due to equipment fault diagnosis technology is a new comprehensive discipline, but also need to further explore and improve in practice. Continuously summarizes and analyzes the entire process of the generation and development of various faults, strives to improve the accuracy of fault diagnosis, and raises the equipment management work to a new level, providing accurate and reliable data for optimizing maintenance methods and reducing maintenance costs.
1 The reason for conducting condition monitoring and fault diagnosis
1.1 Condition Monitoring and Troubleshooting is a New Management Concept
Power plant production is characterized by a high level of automation and strong production continuity. Once a unit fails, it will force the unit to reduce its load and even shut down. Years of beatings and tempering tell us that judging the equipment failures by seeing, touching, hearing, and sniffing can no longer meet the requirements of modern production. Only by performing condition monitoring and troubleshooting can we completely get rid of this. Backward management model.
1.2 Condition Monitoring and Fault Diagnosis Are Needs to Improve Equipment Management Level
Our factory has carried out 8 major repairs. Although the targeted and directional properties have been greatly improved in the establishment of overhaul projects and the replacement of equipment system components, there are still gaps between exactness, suitability, and economy. According to the spirit of the "four commons," the standard requirements for equipment and systems should be more scientific and targeted, and blindness should be reduced. To solve this problem, only state monitoring and fault diagnosis should be carried out.
1.3 Condition monitoring and fault diagnosis are needed to reduce costs and increase efficiency. The cost of repairs in our factory is tightening year-by-year, and the pressure for cost reduction and efficiency increase is increasing year by year. How to further reduce the cost of power generation is a real issue facing the cadres of the whole plant. Judging from the overhaul situation over the years, some units have different degrees of overhaul and overhaul. Excess maintenance means that the workload is increased, the cost is increased, and the human, financial and material waste is caused, and the lack of repair will bring hidden troubles to the operation of the equipment. To carry out condition monitoring and fault diagnosis can effectively avoid unsatisfactory maintenance and overhaul, so as to make the best use and achieve the purpose of cost reduction and efficiency increase.
1.4 Condition monitoring and fault diagnosis are needed in the second phase of production
The two units of the second phase of our plant have been put into operation one after another. If we follow the plans for major repairs in the past three years, we must arrange at least one unit overhaul each year, and even schedule the overhaul of two units in one year. After 8 times of overhaul of the unit, our factory has accumulated rich experience in maintenance and has a deeper understanding of the performance characteristics of equipment and systems. In particular, the technical modification overhaul of the unit in 1999 and 2000 has significantly improved the reliability of the equipment, and basically provided conditions for revising the unit from three years to one year to four years of major repairs. The guarantee for extending the overhaul period is to carry out condition monitoring and fault diagnosis to prolong the service life of equipment and avoid sudden failures.
In recent years, through practice, the understanding of condition monitoring and fault diagnosis has been gradually improved. Through the timing, fixed-point, and fixed-person monitoring of the equipment, especially the on-line monitoring system of Unit #2, multiple equipment accidents have been avoided, which has strengthened us. The determination to carry out this work.
2 The basis for developing condition monitoring and fault diagnosis techniques
2.1 The meaning of status monitoring and fault diagnosis technology
Equipment condition monitoring usually refers to checking whether a device's status is normal by measuring a characteristic parameter of the equipment (such as vibration and temperature). When the characteristic parameter is less than the allowable value, it is considered normal, otherwise it is considered abnormal. The equipment fault diagnosis technology is to know, grasp the status of the online use of the equipment, combine the operating history of the equipment, predict, analyze and judge the faults that may occur or have occurred, and determine the nature, type, degree, and cause of the fault. Parts, indicating the occurrence and development of faults and their consequences, suggesting measures to control the continued development of faults, and eliminating the faults by adopting measures for adjustment, maintenance, and management, and eventually returning the equipment to its normal state.
At present, the equipment condition monitoring and fault diagnosis technology is an important part of modern equipment management and is an indispensable means for equipment management and maintenance management. Especially in today's increasingly fierce market competition, the maintenance and reduction of equipment maintenance costs is one of the most tappable potential for companies. Therefore, the application of condition monitoring and fault diagnosis techniques makes it a historical necessity that predictive maintenance replaces traditional and backward maintenance and regular preventive maintenance.
2.2 Implementing and Enforcing the "Equipment Management Regulations for Ownership-Owned Industrial Transport Enterprises"
Regulations on the Administration of Equipment for All-Urban-owned Industrial Transportation Enterprises. Article 7 of the "Regulations" stipulates: "Enterprises shall actively adopt advanced equipment management methods and maintenance techniques, adopt equipment maintenance methods based on condition monitoring, and continuously improve the modernization level of equipment management and maintenance technology." This provision indicates the direction for enterprises to carry out monitoring of equipment status, so that the leaders and employees of the company clearly define the status and role of condition monitoring technology in the actual equipment management.
The deepening and improvement of the state monitoring work has made us realize that the transition from the planned maintenance system to the state maintenance system is a fundamental reform of the equipment maintenance system and method, and is a concrete embodiment of the idea of ​​seeking truth from facts in the maintenance work. In the reform of the maintenance system, profound changes will take place in the status and role of the staff. They will become passive decision-makers in equipment maintenance from the mere passive maintenance of equipment. The state maintenance system is based on accurate condition monitoring and fault diagnosis, especially real-time online monitoring. The quality of status monitoring work will be related to whether it can be transferred from planned maintenance to status maintenance, the speed of conversion, and the degree of conversion.
3 Status of our plant condition monitoring
3.1 Offline Monitoring
Status Monitoring The major off-line instruments currently available are multifunction data collectors and their supporting software, infrared thermal imagers and their supporting software, vacuum leak detectors and bearing stethoscopes. On-line monitoring of large-scale key auxiliary equipment of Unit #2 has been installed. In the system, various monitoring and monitoring equipment such as vibrometers, spot thermometers, tachometers and other advanced monitoring equipments are all equipped for the operation and maintenance team.
According to the principle of equipment inspection and division of labor, testing points for equipment are set up with inspection cycle, inspection standards and inspection routes; data images from the inspection are analyzed and a monitoring report is issued; in addition to the equipment in question, the related professional is notified in a timely manner. In addition, detailed text descriptions are provided on the standard format exception reports; equipment that should receive attention is shortened in terms of monitoring cycles, and continuous follow-up monitoring is conducted so that early detection and early processing can be conducted to prevent accidents from expanding.
In addition, before the large and minor repairs of the unit, it is generally required to conduct a comprehensive inspection once to provide a reference for the overhaul of the equipment, and to conduct a comprehensive inspection once more to facilitate a comprehensive evaluation of the quality of maintenance. If there are any problems during the start-up of the unit, follow-up monitoring is also required to ensure the safety of the unit.
3.2 Online monitoring
State-based maintenance requests promptly inspect maintenance requests before unit equipment failures, avoid fault shutdowns and unnecessary load disturbances, and maximize the unit's operational reliability. Obviously, condition maintenance requires continuous tracking and analysis of the performance parameters and operating conditions of the unit equipment. The #2 unit has installed a real-time online monitoring system to track and analyze the status of the equipment.
3.3 Strengthen training and continuously improve monitoring
The popularity, depth, and improvement of the monitoring of equipment status is critical to the quality of personnel. Our factory attaches great importance to the training of condition monitoring technicians, and uses various methods such as workshops in the factory, off-site learning, and going in and out, constantly improving the quality and business level of the monitoring personnel. For example, in the process of handling #1 generator vibration in 1999, the training center seized the opportunity to hold a vibration lecture throughout the factory, and asked the senior engineer of the Xi'an Thermal Engineering Institute to give lectures. Shi Gaogong did not give any profound theory when he taught on September 11th, 1999. The central content of the problem is the diagnosis and diagnostic methods. The correctness of diagnostic ideas and the correctness of diagnostic methods will directly affect the accuracy of diagnosis. This training has greatly benefited the diagnostic personnel and brought their diagnostics to a new level.
In order to adapt to the needs of the new two units, the plant reconstructed the original coal conveying system in 2002. The #6 belt was equipped with a new motor and the vibration during the trial operation was as high as 230 μm. The construction unit and the motor purchase unit each insisted. Through tests, the harmonic energy is concentrated on the fundamental frequency, which is a typical feature of the rotor imbalance, but the diagnosis personnel did not make premature conclusions. Instead, according to the diagnostic ideas and methods, the dynamic stiffness of the motor foundation was first examined. Found that the horn between the motor and the foundation is not flat, the wrong position, resulting in insufficient connection rigidity; the motor base is a steel frame welded structure, its support stiffness is seriously insufficient, in order to prove this, the motor is placed on the ground trial operation, The measured vibration is only 12 μm. Therefore, it is no problem to diagnose the newly purchased motor itself, and the dynamic stiffness of the motor base is seriously insufficient, and measures should be taken to reinforce the foundation. After the construction unit grinds the motor base, the vibration of the motor is reduced to less than 20μm.
In August 2003, during the annual audit of marine equipment, the Authority detected that the vibration of the shipbuilding company's 151-ship #2 diesel generator was as high as 287 μm. Although the harmonic energy was concentrated in the fundamental frequency, the diagnosticians used the forward inference method quickly and accurately. Locking the dominant failure to the lack of foundation dynamic stiffness solves a production problem for the shipping company.
4 Effect of Application Status Monitoring and Fault Diagnosis Technology
Incomplete statistics based on work records So far, the State Monitoring and Fault Diagnosis Office has discovered 182 hidden troubles in field equipment, which undoubtedly played an important role in our factory's safe production and avoiding direct or indirect economic losses.
1, on-site dynamic balance vacuum system leak detection
According to incomplete statistics, since 1998, the company has used the data collector to carry out on-site dynamic balancing for 107 times. The steam turbine vacuum system has leaked 28 times and found many leakage points. The maintenance personnel have handled the shutdown according to the leakage degree and repaired the size and size. . This not only prolongs the service life of the equipment, but also drastically changes the practice of asking people to do dynamic balancing and leak checking in the past, saving 1,200,000 yuan for our factory.
2, bearing failure
According to statistics, a total of 32 bearing failures have been detected since 1998, and tracking and monitoring and symptomatic remediation have all greatly extended the bearing life. Among them, there are two serious bearing failures, and we still remember them so far. From February to April 2001, the operation status of the suction fan of unit #1 was extremely unstable, and the axial vibration of the free-end bearing oscillated within 40 to 180 μm. After frequency analysis, combined with the phase test and ferro-iron spectrum analysis, it was determined that The inner ring of the bearing was loose. During the inspection, the journal was found to be heavily worn. After repair, the vibration was only 50 μm. In July 2002, after the maintenance of the #1 unit suction fan was planned, the vibration in the vertical and horizontal directions of the bearing seat was less than 30 μm. The vibration was as high as 204 μm, and it was extremely unstable. The fault diagnosis personnel used the forward reasoning method to find out where the fault was. After replacing the deflected bearing, the vibration was reduced to less than 20 μm so that the fan could resume operation in time.
3, electrical failure
According to statistics, in recent years, a total of 43 hidden troubles in electrical areas have been discovered, providing a basis for leadership decisions. On July 27, 1998, when a fault detector used an infrared thermal imager to perform a routine inspection of the equipment, it was found that the maximum temperature of the A-phase bushing of the #1 main transformer 110KV at the general cap was 62.1°C, and the temperature difference with the phase B was 26.4°C. An emergency power-off repair was performed. The dismantling inspection revealed that more than 30 lines of A-phase cable-breaking cords were broken, and the fault was severely overheated. The cable-wrapped cords had been severely blackened, and the oily carbonization was severe. A major accident was avoided; On the 22nd of the month, the temperature of the top of the #1 main casing of the A-phase main casing was found to be as high as 108.6°C, and the maximum temperature was raised as 80.6°C. The difference in temperature from the same point as B and C was 55.6°C. After disassembling inspection, it was confirmed that the lead copper screw had undergone severe discoloration.
The discovery and elimination of these hidden dangers has brought incalculable economic benefits to our factory. However, this has undoubtedly played a positive role in the process of the establishment of a standard power plant and a first-class power plant in our factory. It is a period safety and economy for our plant managers. The stable operation has made significant contributions.
5 Concluding remarks
The use of condition monitoring and fault diagnosis technology can facilitate, quickly and effectively grasp the operation status of the equipment, eliminate the faults in the bud, improve equipment maintenance, and promote safe production. Although our factory has accumulated certain experience in this area, but due to equipment fault diagnosis technology is a new comprehensive discipline, but also need to further explore and improve in practice. Continuously summarizes and analyzes the entire process of the generation and development of various faults, strives to improve the accuracy of fault diagnosis, and raises the equipment management work to a new level, providing accurate and reliable data for optimizing maintenance methods and reducing maintenance costs.