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Product details
Precautions
Shutdown program
1. Emergency shutdown: During the trial operation of the unit, if any of the following situations occur, an emergency shutdown should be immediately carried out. The operation of emergency shutdown is to press the main motor stop button and then carry out the follow-up work after shutdown.
a. The centrifugal fan suddenly experienced strong vibration and has exceeded the trip value.
b. There are scraping or abnormal friction sounds inside the body.
c. Smoking occurs at any bearing or seal, or the temperature of a certain bearing rises sharply to the alarm value.
d. When the oil pressure is below the alarm value and cannot be restored to normal.
e. The fuel tank level is low and there has been a suction phenomenon.
f. When the axis displacement value shows a significant continuous increase and reaches the alarm value.
2. Normal shutdown: The normal shutdown of the unit should be operated according to the following procedure.
a. Gradually open the vent valve (or outlet bypass valve) while gradually closing the exhaust valve.
b. Gradually close the intake throttle valve to 20-25 °.
c. Press the stop button and pay attention to any abnormal phenomena during the shutdown process.
d. After the unit stops for 5-10 minutes, or when the bearing temperature drops below 45 ℃, the oil supply can be stopped. For units with floating ring seals, the sealed oil pump must continue to supply oil until the body temperature drops below 80 ℃.
After the unit stops, the rotor should be periodically rotated 180 ° within 2-4 hours.
Installation matters
1. The installation of the centrifugal fan unit as a whole should be directly placed on the foundation and leveled with paired diagonal pads.
2. The cutting surface on the base of the centrifugal fan assembled on site should be properly protected and should not be corroded or operated. When the base is placed on the foundation, paired diagonal pads should be used to level it.
3. The bearing seat and base should be tightly connected, and the longitudinal non levelness should not exceed 0.2/1000. The horizontal non levelness should not exceed 0.3/1000 when measured on the main shaft with a spirit level. The horizontal non levelness should not exceed 0.3/1000 when measured on the horizontal split of the bearing seat with a spirit level.
4. Before grinding and scraping the bearing shell, the rotor axis line and the casing axis line should be calibrated, and the gap between the impeller and the air inlet, as well as the gap between the main shaft and the rear plate shaft hole of the casing, should be adjusted to comply with the technical specifications of the equipment.
5. When assembling the main shaft and bearing, inspection should be carried out according to the technical specifications of the equipment. The interference fit between the bearing cover and the bearing shell should be maintained at 0.03-0.04 millimeters (measure the outer diameter of the bearing shell and the inner diameter of the bearing seat).
6. When assembling the fan casing, the position of the casing should be aligned based on the rotor axis line, and the axial and radial clearances between the impeller inlet and the casing inlet should be adjusted to the range specified in the equipment technical documents at high speed. At the same time, the anchor bolts should be checked for tightness. When the clearance value is not specified in the equipment technical documents, the axial clearance should generally be 1/100 of the outer diameter of the impeller, and the radial clearance should be evenly distributed, with a value of 1.5/1000 to 3/1000 of the outer diameter of the impeller (whichever is smaller, take the larger value). When adjusting, strive for a smaller gap value to improve the efficiency of the fan.
7. When aligning the fan, the different axial degrees between the fan shaft and the motor shaft should not exceed 0.05 millimeters for radial positioning and 0.2 millimeters for inclination.
8. The centrifugal fan assembled with rolling bearings has different axial degrees of the bearing holes on the two bearing frames, which can be determined by the flexibility of rotation after the rotor is installed.
Debugging method
A centrifugal fan is a device with a complex structure, mainly composed of an air inlet, an air valve, an impeller, a motor, and an air outlet. The effect of centrifugal fans varies in different states. Therefore, the operating conditions of different parts are not uniform, which will affect the effectiveness of the centrifugal fan. Debugging the centrifugal fan to the desired state can be approached from multiple aspects.
1. Centrifugal fans allow full pressure starting or voltage reduction electric, but it should be noted that the current during full pressure starting is about 5-7 times the rated current, and the voltage reduction starting torque is proportional to the square of the voltage. When the grid capacity is insufficient, voltage reduction starting should be used.
2. During the testing of centrifugal fans, it is necessary to carefully read the product manual and check whether the wiring method is consistent with the wiring diagram; It is necessary to carefully check whether the working voltage of the fan power supply meets the requirements, whether the power supply is out of phase or in phase, and whether the capacity of the electrical components provided meets the requirements.
3. During the test drive, there should be no less than two people, one to control the power supply and one to observe the operation of the fan. If any abnormal phenomena are found, the machine should be stopped immediately for inspection; Firstly, check if the rotation direction is correct; After the centrifugal fan starts running, it should be immediately checked whether the operating currents of each phase are balanced and whether the current exceeds the rated current; If there are any abnormal phenomena, the machine should be stopped for inspection. After running for five minutes, stop the machine and check if there are any abnormalities in the fan. Confirm that there are no abnormalities before starting the machine.
4. When testing a dual speed centrifugal fan, start at low speed first and check if the rotation direction is correct; When starting at high speed, the fan must be stopped before starting to prevent reverse rotation at high speed, which may cause switch tripping and motor damage.
5. When the centrifugal fan reaches normal speed, the input current of the fan should be measured to ensure that it is normal. The operating current of the centrifugal fan should not exceed its rated current. If the operating current exceeds its rated current, check if the supplied voltage is normal.
6. The required motor power for a centrifugal fan refers to the higher power required for the centrifugal fan and fan case when the air inlet is fully open under certain operating conditions. If the air inlet is fully open for operation, there is a risk of damage to the motor. During the fan test run, close the valves on the inlet or outlet pipelines of the fan, gradually open the valves after operation until the required working conditions are reached, and pay attention to whether the operating current of the fan exceeds the rated current.
Strictly following the above debugging method to debug the centrifugal fan can achieve an efficiency of over 98%.
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