High failure rates and low reliability of boiler fans have long plagued the operation and maintenance personnel of power plant boilers. Common fan failures encountered during maintenance and operation include: severe impeller damage; fan vibration; bearing damage; and severe oil leakage from the bearing housing. Diagnosing and analyzing the causes of fan failures and adopting scientific solutions to ensure efficient fan operation and meet production requirements is of great significance. With the rapid development of my country's economy, the energy shortage problem is becoming increasingly prominent, and the demand for energy is gradually increasing. Thermal energy has long been a widely used energy source, and engineering operations, especially power engineering, play a crucial role in the development of many enterprises. Therefore, this article analyzes the problems existing in the development of thermal energy and power engineering and boiler applications, and explores future development directions.
Common Boiler Fan Failure Analysis:
With the development of society, economy, and technology, and the acceleration of social industrialization, various high-tech products have made our production and life more convenient. The induced draft fan is such a high-tech product. However, failures are inevitable during use. Fan failures can be divided into mechanical failures and performance failures. Mechanical fan failures include mechanical malfunctions, mechanical vibration, lubrication system failures, and bearing failures. At best, wear can affect the stable operation of the boiler; at worst, it can force the boiler to shut down, causing significant economic losses. As a major auxiliary device for the boiler, the fan's performance directly impacts the boiler's operation. A detailed analysis of fan malfunctions helps ensure the safe and reliable operation of the boiler.
1. Analysis of the Causes and Countermeasures for Blade Wear
There are many reasons for boiler fan blade wear, mainly including the following: The boiler fan is not operating under designed conditions; the blade inlet arc cut is not aligned with the impeller inlet direction, creating an inlet angle; dust particles in the airflow wear and erode the blade inlet area; the fan inlet is equipped with a cyclone dust collector, which has a good dust removal effect, but if the dust collector is not cleaned in time, dust can easily enter the fan. The airflow generated by the boiler fan carries dust particles to the vicinity of the blades, creating a file-like effect and increasing blade wear; in addition, the weld seams or materials of the fan blades may not have reached a certain hardness, and if high-hardness dust enters, the blade wear and erosion rate will accelerate.
Regarding blade wear failure, the solutions are as follows: First, strengthen the cleaning of dust accumulation in the dust removal equipment to reduce the amount of smoke and dust. Based on the operation of the boiler and coal, the dust accumulation in the dust removal equipment should be cleaned at least once every 2 hours, which can effectively reduce the degree of blade wear and erosion caused by dust particles. Second, reduce exhaust resistance and maintain the consistency between the arc tangent of the blade inlet and the blade flow direction. Third, improve the boiler fan impeller to extend its service life. After modification, replacing the blades behind the fins with single-plate curved blades will increase the load on the motor to some extent, but it can effectively avoid the disruption of balance caused by dust accumulation in the equipment when the blades wear, thus extending the impeller's service life. Fourth, use materials with higher hardness to effectively improve the wear resistance of the boiler fan blades.
2. Fan bearing temperature too high;
During the continuous air delivery process into the boiler, the bearing may experience abnormal temperature rise due to the fan. Practical analysis shows that the causes of excessively high fan bearing temperature include bearing malfunction, insufficient cooling time, and poor lubrication. During normal operation, the fan bearing needs to be cooled with cooling water. If not careful, cooling water can easily enter the boiler room, causing the cooling water pipes to overheat and affecting the bearing's cooling effect. Furthermore, after prolonged operation, the bearing's surface may peel, increasing clearance and also leading to increased bearing temperature. To reduce friction between bearings, lubricating oil is usually applied. However, bearings consume a large amount of lubricating oil during operation, and prolonged operation exacerbates friction. Additionally, during normal fan operation, some water may enter the internal components, continuously damaging the oil film on the bearing surface.
Before addressing fan bearing temperature issues, maintenance personnel can rotate the bearing to listen to its sound and vibration, quickly identifying potential causes of failure and significantly improving troubleshooting rates. During normal fan operation, maintenance personnel can take preventative measures based on a series of issues observed, such as checking the lubricating oil to ensure it is not expired or contaminated. Only in this way can the bearing operate normally. Secondly, the bearing's quality must be rigorously inspected to prevent aging and wear from affecting its operation. Finally, the cooling fan unit must be inspected to ensure its operation meets standard requirements.
3. Excessive Fan Noise.
Issues in the dynamic balance of the fan, or damage to the fan blades during operation, can cause vibration. When the fan starts, the water in the dust collector boils violently, interacting with the fan and generating significant amplitude vibration, which inevitably causes loud noise. Furthermore, the fan is a centrifugal fan, producing a loud whistling sound and noise during operation. Noise pollution from boiler fans seriously affects the rest and health of nearby residents. Therefore, comprehensive noise reduction measures are necessary.
Appropriate auxiliary dust suppression measures can be added to address the problem of excessive dust levels. The fan outlet pipe is connected to a wet scrubber via a long metal pipe. Large dust particles are first removed by the scrubber, and then the gas enters the dust collection and soundproofing chamber. The dust collection and soundproofing chamber uses a combination of expansion tubes and expansion chambers to reduce the gas velocity, allowing small dust particles to fall naturally with the condensation of water vapor in the flue gas, while also providing noise reduction. When low-velocity gas enters the noise reduction chamber and expands further, it is absorbed and reduced in noise by resistive materials. The gas is then guided through pipes to a reactive silencer at the bottom of the chimney, and finally discharged into the atmosphere through an expansion pipe at the top of the chimney. The boiler blower and induced draft fan can be centrally located in the same soundproof fan room. The blower can draw in air from the room, simultaneously removing heat dissipated from the blower, induced draft fan, and flue pipes. The supplementary cool air enters the room through an intake silencer. A silencer is installed on the boiler exhaust pipe. Generally, a small-hole silencer or a multi-layer perforated plate throttling and pressure-reducing combined silencer with small-hole injection is used. Furthermore, the operating distance of the induced draft fan blades within the room can be reduced to decrease their normal operating speed.
4. Severe oil leakage in the bearing housing.
Several factors can cause oil leakage in bearing housings: improper felt ring seal design; unreasonable structural dimensions of the sealing cavity; excessive clearance between the bottom retaining ring and the shaft; improper use of sealing packing; and gaps in the seals due to pressure differential.
Possible measures include: a well-designed felt ring seal structure with oil-blocking devices and return holes. The oil-blocking ring should be fixed to the shaft and rotate with it. This not only prevents oil leakage but also throws out lubricating oil near the sealing cavity opening, effectively preventing leakage. The oil-blocking ring should be placed inside the oil cavity, as close as possible to the sealing cavity, but without rubbing against the outside of the cavity; the gap should be 0.05-0.10 mm. Additionally, a return hole at the bottom of the sealing cavity significantly reduces the tendency for oil leakage.
Another cause: This phenomenon mainly involves a sudden increase in vibration during fan operation. This is because when gas enters the impeller, it has a certain angle with the working surface of the rotating blades. According to fluid mechanics principles, vortices are generated on the non-working surface of the blades, causing dust particles in the gas to slowly deposit on the non-working surface. Airfoil blades are prone to dust accumulation. When the accumulated dust reaches a certain weight, due to the centrifugal force of the rotating impeller, some of the dust is thrown out of the impeller, resulting in uneven dust accumulation on the blades and an unbalanced mass distribution in the impeller, increasing fan vibration.
Solution: In this situation, usually simply cleaning the dust off the blades will reduce fan vibration. The usual method is to temporarily stop the fan and open the inlet door of the fan casing, allowing an inspector to enter and remove the dust from the impeller.
High failure rates and low reliability of boiler fans have long plagued the operation and maintenance personnel of power plant boilers. Common fan failures encountered during maintenance and operation include: severe impeller damage; fan vibration; bearing damage; and severe oil leakage from the bearing housing. Diagnosing and analyzing the causes of fan failures and adopting scientific solutions to ensure efficient fan operation and meet production requirements is of great significance. With the rapid development of my country's economy, the energy shortage problem is becoming increasingly prominent, and the demand for energy is gradually increasing. Thermal energy has long been a widely used energy source, and engineering operations, especially power engineering, play a crucial role in the development of many enterprises. Therefore, this article analyzes the problems existing in the development of thermal energy and power engineering and boiler applications, and explores future development directions.
Common Boiler Fan Failure Analysis:
With the development of society, economy, and technology, and the acceleration of social industrialization, various high-tech products have made our production and life more convenient. The induced draft fan is such a high-tech product. However, failures are inevitable during use. Fan failures can be divided into mechanical failures and performance failures. Mechanical fan failures include mechanical malfunctions, mechanical vibration, lubrication system failures, and bearing failures. At best, wear can affect the stable operation of the boiler; at worst, it can force the boiler to shut down, causing significant economic losses. As a major auxiliary device for the boiler, the fan's performance directly impacts the boiler's operation. A detailed analysis of fan malfunctions helps ensure the safe and reliable operation of the boiler.
1. Analysis of the Causes and Countermeasures for Blade Wear
There are many reasons for boiler fan blade wear, mainly including the following: The boiler fan is not operating under designed conditions; the blade inlet arc cut is not aligned with the impeller inlet direction, creating an inlet angle; dust particles in the airflow wear and erode the blade inlet area; the fan inlet is equipped with a cyclone dust collector, which has a good dust removal effect, but if the dust collector is not cleaned in time, dust can easily enter the fan. The airflow generated by the boiler fan carries dust particles to the vicinity of the blades, creating a file-like effect and increasing blade wear; in addition, the weld seams or materials of the fan blades may not have reached a certain hardness, and if high-hardness dust enters, the blade wear and erosion rate will accelerate.
Regarding blade wear failure, the solutions are as follows: First, strengthen the cleaning of dust accumulation in the dust removal equipment to reduce the amount of smoke and dust. Based on the operation of the boiler and coal, the dust accumulation in the dust removal equipment should be cleaned at least once every 2 hours, which can effectively reduce the degree of blade wear and erosion caused by dust particles. Second, reduce exhaust resistance and maintain the consistency between the arc tangent of the blade inlet and the blade flow direction. Third, improve the boiler fan impeller to extend its service life. After modification, replacing the blades behind the fins with single-plate curved blades will increase the load on the motor to some extent, but it can effectively avoid the disruption of balance caused by dust accumulation in the equipment when the blades wear, thus extending the impeller's service life. Fourth, use materials with higher hardness to effectively improve the wear resistance of the boiler fan blades.
2. Fan bearing temperature too high;
During the continuous air delivery process into the boiler, the bearing may experience abnormal temperature rise due to the fan. Practical analysis shows that the causes of excessively high fan bearing temperature include bearing malfunction, insufficient cooling time, and poor lubrication. During normal operation, the fan bearing needs to be cooled with cooling water. If not careful, cooling water can easily enter the boiler room, causing the cooling water pipes to overheat and affecting the bearing's cooling effect. Furthermore, after prolonged operation, the bearing's surface may peel, increasing clearance and also leading to increased bearing temperature. To reduce friction between bearings, lubricating oil is usually applied. However, bearings consume a large amount of lubricating oil during operation, and prolonged operation exacerbates friction. Additionally, during normal fan operation, some water may enter the internal components, continuously damaging the oil film on the bearing surface.
Before addressing fan bearing temperature issues, maintenance personnel can rotate the bearing to listen to its sound and vibration, quickly identifying potential causes of failure and significantly improving troubleshooting rates. During normal fan operation, maintenance personnel can take preventative measures based on a series of issues observed, such as checking the lubricating oil to ensure it is not expired or contaminated. Only in this way can the bearing operate normally. Secondly, the bearing's quality must be rigorously inspected to prevent aging and wear from affecting its operation. Finally, the cooling fan unit must be inspected to ensure its operation meets standard requirements.
3. Excessive Fan Noise.
Issues in the dynamic balance of the fan, or damage to the fan blades during operation, can cause vibration. When the fan starts, the water in the dust collector boils violently, interacting with the fan and generating significant amplitude vibration, which inevitably causes loud noise. Furthermore, the fan is a centrifugal fan, producing a loud whistling sound and noise during operation. Noise pollution from boiler fans seriously affects the rest and health of nearby residents. Therefore, comprehensive noise reduction measures are necessary.
Appropriate auxiliary dust suppression measures can be added to address the problem of excessive dust levels. The fan outlet pipe is connected to a wet scrubber via a long metal pipe. Large dust particles are first removed by the scrubber, and then the gas enters the dust collection and soundproofing chamber. The dust collection and soundproofing chamber uses a combination of expansion tubes and expansion chambers to reduce the gas velocity, allowing small dust particles to fall naturally with the condensation of water vapor in the flue gas, while also providing noise reduction. When low-velocity gas enters the noise reduction chamber and expands further, it is absorbed and reduced in noise by resistive materials. The gas is then guided through pipes to a reactive silencer at the bottom of the chimney, and finally discharged into the atmosphere through an expansion pipe at the top of the chimney. The boiler blower and induced draft fan can be centrally located in the same soundproof fan room. The blower can draw in air from the room, simultaneously removing heat dissipated from the blower, induced draft fan, and flue pipes. The supplementary cool air enters the room through an intake silencer. A silencer is installed on the boiler exhaust pipe. Generally, a small-hole silencer or a multi-layer perforated plate throttling and pressure-reducing combined silencer with small-hole injection is used. Furthermore, the operating distance of the induced draft fan blades within the room can be reduced to decrease their normal operating speed.
4. Severe oil leakage in the bearing housing.
Several factors can cause oil leakage in bearing housings: improper felt ring seal design; unreasonable structural dimensions of the sealing cavity; excessive clearance between the bottom retaining ring and the shaft; improper use of sealing packing; and gaps in the seals due to pressure differential.
Possible measures include: a well-designed felt ring seal structure with oil-blocking devices and return holes. The oil-blocking ring should be fixed to the shaft and rotate with it. This not only prevents oil leakage but also throws out lubricating oil near the sealing cavity opening, effectively preventing leakage. The oil-blocking ring should be placed inside the oil cavity, as close as possible to the sealing cavity, but without rubbing against the outside of the cavity; the gap should be 0.05-0.10 mm. Additionally, a return hole at the bottom of the sealing cavity significantly reduces the tendency for oil leakage.
Another cause: This phenomenon mainly involves a sudden increase in vibration during fan operation. This is because when gas enters the impeller, it has a certain angle with the working surface of the rotating blades. According to fluid mechanics principles, vortices are generated on the non-working surface of the blades, causing dust particles in the gas to slowly deposit on the non-working surface. Airfoil blades are prone to dust accumulation. When the accumulated dust reaches a certain weight, due to the centrifugal force of the rotating impeller, some of the dust is thrown out of the impeller, resulting in uneven dust accumulation on the blades and an unbalanced mass distribution in the impeller, increasing fan vibration.
Solution: In this situation, usually simply cleaning the dust off the blades will reduce fan vibration. The usual method is to temporarily stop the fan and open the inlet door of the fan casing, allowing an inspector to enter and remove the dust from the impeller.