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Approach:
① Remove the coupling and make the prime mover rotate independently. If there is no abnormal vibration when the prime mover rotates, the fault may be caused by misalignment; check the alignment and refer to the installation manual;
②Check the rotor to see if it is caused by dirt or damage; if necessary, rebalance the rotor;
③ Check the impeller and repair or replace it if necessary;
④ Check the bearings, adjust the gap, and repair or replace if necessary.
⑤Check the balance of the coupling, check the coupling bolts and nuts
⑥ Check and measure the clearance of the seal ring, repair or replace if necessary
⑦ Check the oil pressure, oil temperature and oil system working condition of each oil injection point, find an exception and try to adjust
⑧ Identify the source of dirt, check oil quality, strengthen filtration, regularly change oil, check bearings, adjust clearance
⑨Check whether the compressor is far away from the surge point, whether the anti-surge margin is correct, and whether the anti-surge device is working properly
⑩ The gas pipeline should be well fixed to prevent excessive stress from acting on the compressor cylinder; the pipeline should have sufficient elastic compensation to cope with the amount of thermal expansion
⑪ Separate their bases from each other and increase the elasticity of the connecting pipe
2. Bearing failure: ① The lubrication is abnormal ② The alignment is not correct ③ The bearing clearance does not meet the requirements ④ The compressor or coupling is unbalanced
Approach:
①Make sure to use qualified lubricating oil; regular inspection, no water and dirt should enter the oil
②Check the alignment and adjust if necessary
③ Check the clearance, if necessary, adjust or replace the bearing
④Check the compressor rotor assembly and coupling to see if there is dirt adhesion or rotor assembly defect, if necessary, the rotor should be re-balanced
3. Thrust bearing failure: ①The axial thrust is too large ②The lubrication is abnormal
Approach:
①Check the thrust bearing clearance, check the gas inlet and outlet pressure difference, if necessary, check whether the internal seal ring clearance data exceeds the standard, and check whether the balance disk seal ring clearance between the sections exceeds the standard
②Check oil pump, oil filter and oil cooler, check oil temperature, oil pressure and oil quantity, check oil quality
4. The oil seal ring and the seal ring are faulty and the seal is unstable: ① misalignment and vibration ② dirt in the oil ③ deviations in the seal ring gap ④ insufficient oil pressure ⑤ insufficient accuracy of the seal ring ⑥ the quality of the seal oil and the oil temperature do not meet the requirements
Approach:
①See the vibration section
②Check the oil filter, replace the filter element with dirt; strengthen online filtration
③ Check the gap, if necessary, adjust or replace
④ Check the reference air pressure, not less than the minimum limit
⑤ Check the sealing ring, if necessary, repair or replace
⑥Check oil quality, oil temperature, and solve it
5. The sealing system is unstable and abnormal: ①The accuracy of the sealing ring is not enough ②The quality of the sealing oil or the oil temperature does not meet the requirements ③The oil and air pressure system work poorly ④The sealing part is worn or damaged ⑤The contact wear of the floating ring seat is uneven ⑥Floating The end surface of the ring seat is notched or the sealing surface is worn
Approach:
①Check the sealing ring, if necessary, repair or replace it ②Check the quality of the sealing oil, if the index does not match, replace it; check the temperature of the sealing oil and make adjustments
③ Check the reference air pressure and circuit, and adjust to the specified value; check the working conditions of the components of the differential pressure system
④ After removing the seal, readjust the gap assembly; repair or replace according to the regulations
⑤ Grind, correct the contact surface or replace with new spare parts
⑥ Eliminate suction damage, reduce wear, and replace with new spare parts if necessary
First of all, let me add the fifth point. Due to Xiaode’s personal negligence, I didn’t write it all. I will add it today:
5. The sealing system is unstable and abnormal:
cause:
⑦The sealing ring is broken or damaged (assembly damage or thermal stress damage during idling 0) ⑧The sealing surface, seals, and O-ring are corroded. ⑨The icing of the sealing part due to low temperature operation ⑩Working error of the meter.
Approach:
⑦ May cause damage during assembly, attention should be paid to the assembly; minimize the no-load operation; should be replaced when it cannot be repaired
⑧Analyze the nature of the gas, change the material of the parts or replace with new spare parts
⑨ Eliminate icing, or purify the sealed atmosphere with dry nitrogen
⑩ Check the measuring instruments of the system, and overhaul or replace when found out of alignment
6. The performance of the centrifugal air compressor cannot meet the requirements:
cause:
①Design error ②Manufacturing error ③Difference in gas properties ④Changes in operating conditions ⑤Deposited inclusions ⑥Gap of seal ring is too large
Approach:
①Review the original design and check whether the technical parameters meet the requirements; if problems are found, the seller and the manufacturer should be negotiated and remedial measures taken
② Check the original design and manufacturing process requirements: check the material and processing accuracy; if problems are found, negotiate with the seller and the manufacturer in time
③ Check the various gas properties, such as the difference between the gas properties of the original design is too large, it will inevitably affect the compressor performance indicators; according to actual needs and may try to solve
④ The actual operating conditions are too different from the design conditions, which will inevitably cause the compressor's operating performance to deviate from the design performance.
⑤ Is there any inclusion in the gas flow path, impeller and cylinder, if there is, it should be removed
⑥Check the clearance of each part, if it does not meet the requirements, it must be adjusted or replaced
7. Centrifugal air compressor surge:
cause:
① The operating point falls into the surge zone or is too close to the surge boundary ② The anti-surge margin is not set enough ③ The suction flow is not enough ④ The compressor outlet gas system pressure is too high ⑤ The vent valve or return valve is not opened in time when the operating conditions change ⑥The anti-surge device is not turned on automatically. ⑦The anti-surge device or mechanism is inaccurate or malfunctions. ⑧The setting value of the anti-surge device is inaccurate. ⑨The speed is increased and the pressure is too fast. ⑩The speed is not reduced first. ⑪The gas property changes or the state changes seriously Compressor parts are damaged and fall off ⑫ Check valve on gas outlet line of compressor is not working
Approach:
①Check the position of the operating point on the compressor characteristic line, if it is too close to the surge boundary or falls into the surge area, the working conditions should be adjusted in time and the surge should be eliminated
②Pre-measure the anti-surge margin under various working conditions; the anti-surge margin line should be adjusted to the best
③The opening of the intake valve may be insufficient, the valve core is too dirty or frozen, the intake passage is blocked, and the inlet air source is reduced or cut off. Should find out the reason and try to solve it
④The gas is not emptied or returned when the compressor decelerates or stops; the outlet check valve fails or is not strict, and the gas is poured back; the cause should be found and measures taken
⑤ When the inlet flow rate is reduced or the speed is reduced, or the speed is rapidly increased, the cause should be found out; the anti-surge vent or return valve should be opened in time
⑥ During normal operation, the anti-surge device should be turned on automatically
⑦ Regularly check the working condition of anti-surge device, if it is found to be out of order, misaligned or jammed, and the action is not working, it should be resolved in time
⑧ Strictly set the anti-surge value, and regularly test, found that the value is not allowed to correct in time
⑨ Change of working condition, the speed-up and pressure-up should not be too fierce or too fast.
⑩Before reducing the speed, the pressure should be reduced to avoid surge
⑪When the nature or state of the gas changes, the characteristic line should be converted, and the anti-surge value should be adjusted according to the changed characteristic line. The interstage seal, the balance plate seal, and the O-ring breakage or fall will induce surge; it should be checked frequently to make it In good condition
⑫ The industrial reverse valve on the compressor outlet gas line should be checked frequently to keep the action flexible and reliable; to avoid the speed reduction or gas backfill when the machine is stopped
8. Damage to the impeller of the centrifugal air compressor:
cause:
①Unqualified material, insufficient strength ②Poor working conditions (decreased strength) ③Excessive load, reduced strength ④Abnormal vibration, collision between dynamic and static parts ⑤Inclusions.
Approach:
①Re-examine the materials used in the original design and manufacturing, if the materials are not qualified, the impeller should be replaced
②The working conditions do not meet the requirements. Due to the bad conditions, the strength is reduced. The working conditions should be improved to meet the design.
③ Due to the excessively high speed or too large flow and pressure ratio, the strength of the impeller is reduced, causing damage; severe overload or overspeed operation is prohibited
④ Excessive vibration will cause the rotating part to contact and collide with the stationary part, resulting in damage; it is strictly forbidden to operate with excessive vibration value; eliminate abnormal vibration
⑤ Inclusions in the compressor damage the impeller or other parts; entry of the inclusions into the compressor is strictly prohibited; check whether the inlet filter is damaged
9. Leakage of centrifugal air compressor:
cause:
①Deposited inclusions②Stress corrosion and chemical corrosion The sealing system is not working well ③O-shaped sealing ring is bad ④The cylinder or pipe joint is leaking ⑤The sealant is invalid ⑥The operation is abnormal ⑦The sealing ring is damaged, broken, corroded and worn
Approach:
①Keep the gas clean, and remove the deposit as soon as possible in the flow part and the cylinder
②Prevent stress concentration, prevent harmful components from entering the compressor, and do anti-corrosion measures for the compressor. Check the components of the sealing system, find the cause and solve it in time
③ Check each O-ring, and replace it if it is found to be bad or aging
④ Check the joint surface of the cylinder and the flange joints, and take measures in time if air leakage is found
⑤ Check the sealant and packing in the split surface and other parts of the cylinder, if it is found to be invalid, it should be replaced
⑥Check whether the operation index is correct, check the running state of the compressor, find that it is abnormal and solve it in time
⑦ Check each sealing ring; if it is found to be broken, damaged, worn or corroded, the cause should be found out and repaired or replaced when it is gray
10. Insufficient flow and exhaust of centrifugal air compressor:
cause:
①There is a problem with the flow rate ②The compressor reverses ③The suction pressure is low ④The molecular weight does not match ⑤The speed of the prime mover is lower than the design speed ⑥The circulation volume from the discharge side to the suction side increases ⑦The pressure gauge or flowmeter is faulty
Approach:
①Comparison study of exhaust pressure and flow with the characteristic curve to see if it meets to find the problem
②Check the direction of rotation, the direction of rotation should be consistent with the direction of the arrow on the compressor casing
③Check the inlet filter
④ Determine the actual molecular weight of the gas and compare it with the specified value in the manual; if the actual molecular weight is less than the specified value, the exhaust pressure will be insufficient
⑤Check the running speed of the compressor, and compare it with the manual; if the speed is indeed low, the speed of the prime mover should be increased
⑥Check the circulating gas volume, check the external piping; check the opening of the circulating gas valve, if the circulating volume is too large, it should be adjusted
⑦ Check each meter and find out that the problem should be adjusted, repaired or replaced
11. The prime mover is overloaded:
cause:
①The molecular weight is greater than the specified value ②The electrical problem of the original motor ③The surface of the diffuser adjacent to the impeller is corroded, the degree of diffusion is reduced ④The deformation of the impeller or the diffuser ⑤The rotating part meets the static part ⑥The suction pressure is high
Approach:
①Check the actual molecular weight of the gas and compare with the design specification
②Check the thermal capacity and operating status of the circuit breaker; check whether the voltage is reduced; check whether the current difference of each phase is within 3%; find the problem and solve it in time
③ Dismantle and check the flow channels of the diffuser. If there is corrosion, the material or surface hardness should be improved; clean the surface to make the surface smooth; if the impeller collides with the diffuser or the diffuser is deformed, it should be replaced
④ Impeller or diffuser deformation should be repaired or replaced
⑤ Disassemble the compressor and gear box of the prime mover; check the clearance of each part and compare with the instruction manual; find the problem and solve it in time
⑥ The suction pressure is high, the weight flow increases, and the power consumption is large; compare with the design data to find out the reason. And resolve.
Common failure causes of centrifugal compressors
First, the bearing temperature rises
The working temperature of centrifugal compressor bearings is generally 45~50℃, and the maximum temperature should not exceed 65℃. Generally, 65℃ is the alarm temperature, and 75℃ is the interlock shutdown temperature. The reasons for the high bearing temperature are:
(1) The clearance between the bearing bush and the journal is too small, and the shoe scraping should be performed to adjust the clearance;
⑵ The diameter of the bearing oil inlet throttle ring is small, and the oil intake is insufficient. The throttle hole diameter should be appropriately increased;
(3) The oil inlet temperature is too high. The cooling water volume of the oil cooler should be adjusted;
⑷The oil is mixed with water or dirty or deteriorated, which affects the lubrication effect. The oil cooler should be checked to eliminate water leakage failure or replace with new oil;
⑸ Dirt enters the bearing and wears out the bearing shell. Should clean the bearing and lubricating oil pipeline, and scrape the bush;
⑹ The bearing bush is damaged, and the bearing bush should be recast.
Second, what is "surging"
Surge is a kind of vibration under abnormal operating conditions that occurs when the flow rate of a turbine compressor is reduced to a certain degree. Centrifugal compressors are a form of turbine compressors. Surge is very harmful to centrifugal compressors.
When centrifugal compressor surge occurs, the typical phenomena are:
The outlet pressure of the compressor initially increased first, then fell sharply, and showed large periodic fluctuations;
The flow rate of the compressor drops sharply and fluctuates greatly. In serious cases, even the air backfills into the suction pipe;
The current and power meter of the motor driving the compressor indicate instability and large fluctuations;
The machine generates strong vibration and emits abnormal airflow noise at the same time.
Third, the factors affecting the exhaust volume
There are many factors that affect the displacement of centrifugal compressors. In addition to design, manufacturing, and installation, the factors that can affect the displacement of compressors during operation are:
1. The air filter is clogged or the resistance increases, causing the compressor suction pressure to decrease. When the outlet pressure is constant, the compressor pressure ratio is increased. According to the compressor performance curve, when the pressure ratio increases, the amount of exhaust gas decreases;
2. The air separation equipment pipeline is blocked, the resistance increases or the valve fails, causing the compressor suction pressure to increase. When the suction pressure is constant, the pressure ratio increases, resulting in a reduction in exhaust volume;
3. The intercooler of the compressor is blocked or the resistance is increased, which causes the discharge volume to decrease. However, the situation at different locations is different: if the resistance of the air side of the cooler increases, only the internal resistance of the machine is increased, which reduces the efficiency of the compressor and the amount of exhaust gas; if the resistance of the water side increases, the amount of circulating cooling water Reduced, the gas cooling is not good, which affects the next stage of suction and reduces the compressor's exhaust volume;
4. Poor sealing, causing gas leakage. include:
(1) Internal leakage, that is, blow-by gas between stages. The compressed gas is returned, and the second compression is performed. It will affect the working conditions at all levels, increase the pressure ratio of the low-pressure stage, and decrease the pressure ratio of the high-pressure stage, so that the entire compressor deviates from the design conditions and the discharge volume decreases;
(2) External leakage, that is, air leakage from the shaft end seal to the outside of the casing. Although the suction volume remains unchanged, a part of the compressed gas leaks, which naturally causes a reduction in the discharge volume;
5. The cooler leaks. If the first stage leaks, because the water-side pressure is higher than the gas-side pressure, the cooling water will enter the gas-side channel and be further entrained by the airflow into the impeller and diffuser. After a certain period of time, it will cause scaling and blockage and reduce the air flow. If the secondary or tertiary cooler leaks, the compressed air will leak into the cooling water and run away because the pressure on the gas side is higher than that on the water side, reducing the amount of exhaust;
6. The frequency or voltage of the power grid decreases, causing the motor and compressor speed to decrease, and the discharge volume to decrease;
7. If the temperature of inhalation increases at any level, the density of gas decreases, and the amount of inhalation decreases.
4. Sealing air leakage
Leakage between the wheel cover seal and the interstage seal is internal leakage. Severe internal leakage will increase the energy loss of the compressor, reduce the stage efficiency and compressor efficiency, and reduce the exhaust volume. However, the influence mechanism of the two is also different: the leakage of the wheel cover seal is to return the compressed gas back to the impeller, and then perform the second stage compression, which mainly increases the total power consumption of the stage; the leakage of the interstage seal is The blow-by gas between stages will increase the low-pressure stage pressure ratio and decrease the high-pressure stage pressure ratio.
The serious leakage of the balance disc seal has little effect on the performance of the compressor, but it is very important for the safe operation of the centrifugal compressor.
The leakage of the shaft seal is external leakage. External leakage refers to the leakage of gas from the seal to the case. It goes without saying that serious external leakage will directly reduce the compressor displacement.
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Approach:
① Remove the coupling and make the prime mover rotate independently. If there is no abnormal vibration when the prime mover rotates, the fault may be caused by misalignment; check the alignment and refer to the installation manual;
②Check the rotor to see if it is caused by dirt or damage; if necessary, rebalance the rotor;
③ Check the impeller and repair or replace it if necessary;
④ Check the bearings, adjust the gap, and repair or replace if necessary.
⑤Check the balance of the coupling, check the coupling bolts and nuts
⑥ Check and measure the clearance of the seal ring, repair or replace if necessary
⑦ Check the oil pressure, oil temperature and oil system working condition of each oil injection point, find an exception and try to adjust
⑧ Identify the source of dirt, check oil quality, strengthen filtration, regularly change oil, check bearings, adjust clearance
⑨Check whether the compressor is far away from the surge point, whether the anti-surge margin is correct, and whether the anti-surge device is working properly
⑩ The gas pipeline should be well fixed to prevent excessive stress from acting on the compressor cylinder; the pipeline should have sufficient elastic compensation to cope with the amount of thermal expansion
⑪ Separate their bases from each other and increase the elasticity of the connecting pipe
2. Bearing failure: ① The lubrication is abnormal ② The alignment is not correct ③ The bearing clearance does not meet the requirements ④ The compressor or coupling is unbalanced
Approach:
①Make sure to use qualified lubricating oil; regular inspection, no water and dirt should enter the oil
②Check the alignment and adjust if necessary
③ Check the clearance, if necessary, adjust or replace the bearing
④Check the compressor rotor assembly and coupling to see if there is dirt adhesion or rotor assembly defect, if necessary, the rotor should be re-balanced
3. Thrust bearing failure: ①The axial thrust is too large ②The lubrication is abnormal
Approach:
①Check the thrust bearing clearance, check the gas inlet and outlet pressure difference, if necessary, check whether the internal seal ring clearance data exceeds the standard, and check whether the balance disk seal ring clearance between the sections exceeds the standard
②Check oil pump, oil filter and oil cooler, check oil temperature, oil pressure and oil quantity, check oil quality
4. The oil seal ring and the seal ring are faulty and the seal is unstable: ① misalignment and vibration ② dirt in the oil ③ deviations in the seal ring gap ④ insufficient oil pressure ⑤ insufficient accuracy of the seal ring ⑥ the quality of the seal oil and the oil temperature do not meet the requirements
Approach:
①See the vibration section
②Check the oil filter, replace the filter element with dirt; strengthen online filtration
③ Check the gap, if necessary, adjust or replace
④ Check the reference air pressure, not less than the minimum limit
⑤ Check the sealing ring, if necessary, repair or replace
⑥Check oil quality, oil temperature, and solve it
5. The sealing system is unstable and abnormal: ①The accuracy of the sealing ring is not enough ②The quality of the sealing oil or the oil temperature does not meet the requirements ③The oil and air pressure system work poorly ④The sealing part is worn or damaged ⑤The contact wear of the floating ring seat is uneven ⑥Floating The end surface of the ring seat is notched or the sealing surface is worn
Approach:
①Check the sealing ring, if necessary, repair or replace it ②Check the quality of the sealing oil, if the index does not match, replace it; check the temperature of the sealing oil and make adjustments
③ Check the reference air pressure and circuit, and adjust to the specified value; check the working conditions of the components of the differential pressure system
④ After removing the seal, readjust the gap assembly; repair or replace according to the regulations
⑤ Grind, correct the contact surface or replace with new spare parts
⑥ Eliminate suction damage, reduce wear, and replace with new spare parts if necessary
First of all, let me add the fifth point. Due to Xiaode’s personal negligence, I didn’t write it all. I will add it today:
5. The sealing system is unstable and abnormal:
cause:
⑦The sealing ring is broken or damaged (assembly damage or thermal stress damage during idling 0) ⑧The sealing surface, seals, and O-ring are corroded. ⑨The icing of the sealing part due to low temperature operation ⑩Working error of the meter.
Approach:
⑦ May cause damage during assembly, attention should be paid to the assembly; minimize the no-load operation; should be replaced when it cannot be repaired
⑧Analyze the nature of the gas, change the material of the parts or replace with new spare parts
⑨ Eliminate icing, or purify the sealed atmosphere with dry nitrogen
⑩ Check the measuring instruments of the system, and overhaul or replace when found out of alignment
6. The performance of the centrifugal air compressor cannot meet the requirements:
cause:
①Design error ②Manufacturing error ③Difference in gas properties ④Changes in operating conditions ⑤Deposited inclusions ⑥Gap of seal ring is too large
Approach:
①Review the original design and check whether the technical parameters meet the requirements; if problems are found, the seller and the manufacturer should be negotiated and remedial measures taken
② Check the original design and manufacturing process requirements: check the material and processing accuracy; if problems are found, negotiate with the seller and the manufacturer in time
③ Check the various gas properties, such as the difference between the gas properties of the original design is too large, it will inevitably affect the compressor performance indicators; according to actual needs and may try to solve
④ The actual operating conditions are too different from the design conditions, which will inevitably cause the compressor's operating performance to deviate from the design performance.
⑤ Is there any inclusion in the gas flow path, impeller and cylinder, if there is, it should be removed
⑥Check the clearance of each part, if it does not meet the requirements, it must be adjusted or replaced
7. Centrifugal air compressor surge:
cause:
① The operating point falls into the surge zone or is too close to the surge boundary ② The anti-surge margin is not set enough ③ The suction flow is not enough ④ The compressor outlet gas system pressure is too high ⑤ The vent valve or return valve is not opened in time when the operating conditions change ⑥The anti-surge device is not turned on automatically. ⑦The anti-surge device or mechanism is inaccurate or malfunctions. ⑧The setting value of the anti-surge device is inaccurate. ⑨The speed is increased and the pressure is too fast. ⑩The speed is not reduced first. ⑪The gas property changes or the state changes seriously Compressor parts are damaged and fall off ⑫ Check valve on gas outlet line of compressor is not working
Approach:
①Check the position of the operating point on the compressor characteristic line, if it is too close to the surge boundary or falls into the surge area, the working conditions should be adjusted in time and the surge should be eliminated
②Pre-measure the anti-surge margin under various working conditions; the anti-surge margin line should be adjusted to the best
③The opening of the intake valve may be insufficient, the valve core is too dirty or frozen, the intake passage is blocked, and the inlet air source is reduced or cut off. Should find out the reason and try to solve it
④The gas is not emptied or returned when the compressor decelerates or stops; the outlet check valve fails or is not strict, and the gas is poured back; the cause should be found and measures taken
⑤ When the inlet flow rate is reduced or the speed is reduced, or the speed is rapidly increased, the cause should be found out; the anti-surge vent or return valve should be opened in time
⑥ During normal operation, the anti-surge device should be turned on automatically
⑦ Regularly check the working condition of anti-surge device, if it is found to be out of order, misaligned or jammed, and the action is not working, it should be resolved in time
⑧ Strictly set the anti-surge value, and regularly test, found that the value is not allowed to correct in time
⑨ Change of working condition, the speed-up and pressure-up should not be too fierce or too fast.
⑩Before reducing the speed, the pressure should be reduced to avoid surge
⑪When the nature or state of the gas changes, the characteristic line should be converted, and the anti-surge value should be adjusted according to the changed characteristic line. The interstage seal, the balance plate seal, and the O-ring breakage or fall will induce surge; it should be checked frequently to make it In good condition
⑫ The industrial reverse valve on the compressor outlet gas line should be checked frequently to keep the action flexible and reliable; to avoid the speed reduction or gas backfill when the machine is stopped
8. Damage to the impeller of the centrifugal air compressor:
cause:
①Unqualified material, insufficient strength ②Poor working conditions (decreased strength) ③Excessive load, reduced strength ④Abnormal vibration, collision between dynamic and static parts ⑤Inclusions.
Approach:
①Re-examine the materials used in the original design and manufacturing, if the materials are not qualified, the impeller should be replaced
②The working conditions do not meet the requirements. Due to the bad conditions, the strength is reduced. The working conditions should be improved to meet the design.
③ Due to the excessively high speed or too large flow and pressure ratio, the strength of the impeller is reduced, causing damage; severe overload or overspeed operation is prohibited
④ Excessive vibration will cause the rotating part to contact and collide with the stationary part, resulting in damage; it is strictly forbidden to operate with excessive vibration value; eliminate abnormal vibration
⑤ Inclusions in the compressor damage the impeller or other parts; entry of the inclusions into the compressor is strictly prohibited; check whether the inlet filter is damaged
9. Leakage of centrifugal air compressor:
cause:
①Deposited inclusions②Stress corrosion and chemical corrosion The sealing system is not working well ③O-shaped sealing ring is bad ④The cylinder or pipe joint is leaking ⑤The sealant is invalid ⑥The operation is abnormal ⑦The sealing ring is damaged, broken, corroded and worn
Approach:
①Keep the gas clean, and remove the deposit as soon as possible in the flow part and the cylinder
②Prevent stress concentration, prevent harmful components from entering the compressor, and do anti-corrosion measures for the compressor. Check the components of the sealing system, find the cause and solve it in time
③ Check each O-ring, and replace it if it is found to be bad or aging
④ Check the joint surface of the cylinder and the flange joints, and take measures in time if air leakage is found
⑤ Check the sealant and packing in the split surface and other parts of the cylinder, if it is found to be invalid, it should be replaced
⑥Check whether the operation index is correct, check the running state of the compressor, find that it is abnormal and solve it in time
⑦ Check each sealing ring; if it is found to be broken, damaged, worn or corroded, the cause should be found out and repaired or replaced when it is gray
10. Insufficient flow and exhaust of centrifugal air compressor:
cause:
①There is a problem with the flow rate ②The compressor reverses ③The suction pressure is low ④The molecular weight does not match ⑤The speed of the prime mover is lower than the design speed ⑥The circulation volume from the discharge side to the suction side increases ⑦The pressure gauge or flowmeter is faulty
Approach:
①Comparison study of exhaust pressure and flow with the characteristic curve to see if it meets to find the problem
②Check the direction of rotation, the direction of rotation should be consistent with the direction of the arrow on the compressor casing
③Check the inlet filter
④ Determine the actual molecular weight of the gas and compare it with the specified value in the manual; if the actual molecular weight is less than the specified value, the exhaust pressure will be insufficient
⑤Check the running speed of the compressor, and compare it with the manual; if the speed is indeed low, the speed of the prime mover should be increased
⑥Check the circulating gas volume, check the external piping; check the opening of the circulating gas valve, if the circulating volume is too large, it should be adjusted
⑦ Check each meter and find out that the problem should be adjusted, repaired or replaced
11. The prime mover is overloaded:
cause:
①The molecular weight is greater than the specified value ②The electrical problem of the original motor ③The surface of the diffuser adjacent to the impeller is corroded, the degree of diffusion is reduced ④The deformation of the impeller or the diffuser ⑤The rotating part meets the static part ⑥The suction pressure is high
Approach:
①Check the actual molecular weight of the gas and compare with the design specification
②Check the thermal capacity and operating status of the circuit breaker; check whether the voltage is reduced; check whether the current difference of each phase is within 3%; find the problem and solve it in time
③ Dismantle and check the flow channels of the diffuser. If there is corrosion, the material or surface hardness should be improved; clean the surface to make the surface smooth; if the impeller collides with the diffuser or the diffuser is deformed, it should be replaced
④ Impeller or diffuser deformation should be repaired or replaced
⑤ Disassemble the compressor and gear box of the prime mover; check the clearance of each part and compare with the instruction manual; find the problem and solve it in time
⑥ The suction pressure is high, the weight flow increases, and the power consumption is large; compare with the design data to find out the reason. And resolve.
Common failure causes of centrifugal compressors
First, the bearing temperature rises
The working temperature of centrifugal compressor bearings is generally 45~50℃, and the maximum temperature should not exceed 65℃. Generally, 65℃ is the alarm temperature, and 75℃ is the interlock shutdown temperature. The reasons for the high bearing temperature are:
(1) The clearance between the bearing bush and the journal is too small, and the shoe scraping should be performed to adjust the clearance;
⑵ The diameter of the bearing oil inlet throttle ring is small, and the oil intake is insufficient. The throttle hole diameter should be appropriately increased;
(3) The oil inlet temperature is too high. The cooling water volume of the oil cooler should be adjusted;
⑷The oil is mixed with water or dirty or deteriorated, which affects the lubrication effect. The oil cooler should be checked to eliminate water leakage failure or replace with new oil;
⑸ Dirt enters the bearing and wears out the bearing shell. Should clean the bearing and lubricating oil pipeline, and scrape the bush;
⑹ The bearing bush is damaged, and the bearing bush should be recast.
Second, what is "surging"
Surge is a kind of vibration under abnormal operating conditions that occurs when the flow rate of a turbine compressor is reduced to a certain degree. Centrifugal compressors are a form of turbine compressors. Surge is very harmful to centrifugal compressors.
When centrifugal compressor surge occurs, the typical phenomena are:
The outlet pressure of the compressor initially increased first, then fell sharply, and showed large periodic fluctuations;
The flow rate of the compressor drops sharply and fluctuates greatly. In serious cases, even the air backfills into the suction pipe;
The current and power meter of the motor driving the compressor indicate instability and large fluctuations;
The machine generates strong vibration and emits abnormal airflow noise at the same time.
Third, the factors affecting the exhaust volume
There are many factors that affect the displacement of centrifugal compressors. In addition to design, manufacturing, and installation, the factors that can affect the displacement of compressors during operation are:
1. The air filter is clogged or the resistance increases, causing the compressor suction pressure to decrease. When the outlet pressure is constant, the compressor pressure ratio is increased. According to the compressor performance curve, when the pressure ratio increases, the amount of exhaust gas decreases;
2. The air separation equipment pipeline is blocked, the resistance increases or the valve fails, causing the compressor suction pressure to increase. When the suction pressure is constant, the pressure ratio increases, resulting in a reduction in exhaust volume;
3. The intercooler of the compressor is blocked or the resistance is increased, which causes the discharge volume to decrease. However, the situation at different locations is different: if the resistance of the air side of the cooler increases, only the internal resistance of the machine is increased, which reduces the efficiency of the compressor and the amount of exhaust gas; if the resistance of the water side increases, the amount of circulating cooling water Reduced, the gas cooling is not good, which affects the next stage of suction and reduces the compressor's exhaust volume;
4. Poor sealing, causing gas leakage. include:
(1) Internal leakage, that is, blow-by gas between stages. The compressed gas is returned, and the second compression is performed. It will affect the working conditions at all levels, increase the pressure ratio of the low-pressure stage, and decrease the pressure ratio of the high-pressure stage, so that the entire compressor deviates from the design conditions and the discharge volume decreases;
(2) External leakage, that is, air leakage from the shaft end seal to the outside of the casing. Although the suction volume remains unchanged, a part of the compressed gas leaks, which naturally causes a reduction in the discharge volume;
5. The cooler leaks. If the first stage leaks, because the water-side pressure is higher than the gas-side pressure, the cooling water will enter the gas-side channel and be further entrained by the airflow into the impeller and diffuser. After a certain period of time, it will cause scaling and blockage and reduce the air flow. If the secondary or tertiary cooler leaks, the compressed air will leak into the cooling water and run away because the pressure on the gas side is higher than that on the water side, reducing the amount of exhaust;
6. The frequency or voltage of the power grid decreases, causing the motor and compressor speed to decrease, and the discharge volume to decrease;
7. If the temperature of inhalation increases at any level, the density of gas decreases, and the amount of inhalation decreases.
4. Sealing air leakage
Leakage between the wheel cover seal and the interstage seal is internal leakage. Severe internal leakage will increase the energy loss of the compressor, reduce the stage efficiency and compressor efficiency, and reduce the exhaust volume. However, the influence mechanism of the two is also different: the leakage of the wheel cover seal is to return the compressed gas back to the impeller, and then perform the second stage compression, which mainly increases the total power consumption of the stage; the leakage of the interstage seal is The blow-by gas between stages will increase the low-pressure stage pressure ratio and decrease the high-pressure stage pressure ratio.
The serious leakage of the balance disc seal has little effect on the performance of the compressor, but it is very important for the safe operation of the centrifugal compressor.
The leakage of the shaft seal is external leakage. External leakage refers to the leakage of gas from the seal to the case. It goes without saying that serious external leakage will directly reduce the compressor displacement.Subscribe to relevant news content?
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