In most production workshops, it is necessary to choose a centrifugal fan as the main ventilation equipment. After choosing a suitable centrifugal fan, it is necessary to determine the appropriate location for correct installation in order to ensure the normal ventilation effect. , so how to install the centrifugal fan is correct?
1) Centrifugal fan installation requirements
1. The installation of the centrifugal fan should be placed on a basically level ground and a shock absorber should be installed. For centrifugal fans assembled on site, the drilling and processing surface on the base should be properly protected from rust. When the base is placed on the ground, it should be in full contact with the ground. The bearing seat of the fan should be closely connected with the overall base of the fan, and the installation position should be confirmed to be firm.
2. When assembling the casing, the positions of the casing and the air inlet of the centrifugal fan shall be located on the basis of the axis of the rotor, and the axial and radial clearances between the impeller inlet and the casing inlet shall be adjusted according to the equipment technology. Within the scope specified in the document, at the same time check whether the anchor bolts are tight. If the clearance value is not specified in the equipment technical documents, the general axial clearance should be 1/100 of the outer diameter of the impeller, and the radial clearance should be evenly distributed, and its value should be 1.5/1000~3/1000 of the outer diameter of the impeller (outer diameter The smaller one takes the larger value). When adjusting, try to make the gap value smaller to improve the stability of the centrifugal fan.
3. When the centrifugal fan is aligned, the axial offset cannot exceed 0.025mm, and the skew cannot exceed 0.3/1500. For fans equipped with rolling bearings, after the rotor is installed, the coaxiality of the bearing holes on the two bearing frames should be able to rotate flexibly. When the main shaft bearing and piston pin are assembled, they should be inspected according to the requirements of the technical documentation of the equipment, and a clearance fit of 0.02~0.04mm should be maintained between the bearing cover and the piston pin (accurately measure the diameter of the piston pin and the nominal diameter of the seated bearing).
2)Centrifugal fan installation steps
1. Preparation for installation
(1) Check and number the equipment, check the appearance quality of the equipment, and check the dimensions of each component against the drawings given by the manufacturer.
(2) Mark the foundation, check the elevation and levelness of the foundation, and check the relative positions of the anchor bolt holes of each component.
(3) Configure iron pads according to the elevation and levelness of the foundation of the centrifugal fan to be measured, and the number of iron pads is generally ≤4.
2. Install fan foundation
(1) Level the foundation, place anchor bolts, and arrange shims. The shim group is generally 2 flat, 1 inclined, and 3 shims. The thicker ones should be placed below. The inclined shims should be used in pairs and extend about 20mm out of the machine frame. , After alignment, it should be welded firmly and not loosened.
(2) The pad iron should be placed on the main load-bearing platform of the equipment, the vertical reinforcement of the machine frame or both sides of the anchor bolts, and it should be as close to the anchor bolt holes as possible without affecting the secondary grouting.
3. Install the case
(1) Put the anchor bolts into the bolt holes, and lift the lower half of the casing into place.
(2) When the casing is assembled, the position of the casing should be corrected based on the axis of the rotor and the axial and radial clearance between the impeller inlet and the casing inlet should be within the range specified in the equipment technical documents at high speed. Inside, at the same time check whether the anchor bolts are tight. If the clearance value is not stipulated in the equipment technical documents, the general axial clearance should be 1/100 of the outer diameter of the impeller, and the radial clearance should be evenly distributed, and its value should be 1.5/1000~3/1000 of the outer diameter of the impeller The smaller one takes the larger value). When adjusting, try to make the gap value smaller to improve the efficiency of the centrifugal fan.
(3) The installation work on the upper part of the casing should be carried out after the rotor is in place (including impeller centering).
4. Install the bearing seat
(1) Mark the center line on the bearing seat before installation, put the anchor bolts into the bolt holes, hoist the bearing seat in place, and adjust to align the vertical and horizontal center lines with the foundation center line.
(2) Make the elevation and levelness of the bearing seat meet the requirements of the drawing by adjusting the iron pad, and at the same time check whether the centerlines of the two bearing seats are aligned.
(3) After the bearing seat is aligned, the bearing seat can be grouted once.
(4) The bearing seat and the base should be closely connected, and the longitudinal non-levelness should not exceed 0.2/1000. Measure it on the main shaft with a level meter. The horizontal non-level bottom should not exceed 0.3/1000. Use a level meter to divide the plane in the level of the bearing seat Measure on.
5. Install the rotor
(1) After the rotor is hoisted in place, adjust the parameters such as rotor levelness and various clearance values. The horizontal deviation of the main shaft should be below 0.1mm/m, and the vertical and horizontal horizontal deviation of the bearing seat should be below 0.4mm/m.
(2) After the rotor is aligned, perform secondary grouting on the bearing seat, and tighten the anchor bolts and nuts when the concrete strength meets the requirements.
6. Install the air inlet
(1) Install the air inlet according to the requirements of the drawings. The air inlets are fixed on the casing by bolts. Adjust the casing so that the radial and axial clearances between the impeller and the bell mouth of the air inlet meet the requirements of the drawings.
(2) After passing the acceptance check, pour the anchor bolt holes of the casing.
7. Install the motor
(1) Install the motor end coupling. Put the anchor bolts in the anchor bolt holes and install the motor platform.
(2) Hoist the motor in place, and after initially aligning the center line, connect the motor coupling with the intermediate shaft according to the mark.
(3) Alignment of the motor, with the centrifugal fan as the benchmark, install dial gauges on the bearing seat coupling and the motor coupling respectively, measure the axial deviation of the coupling, and align the motor by adjusting the pad iron. Horizontally and vertically.
(4) After the alignment is qualified, pour the anchor bolts. When the concrete strength meets the requirements, tighten the anchor bolt nuts, check the alignment of the motor, and tighten the anchor bolts according to the specified torque.
8. Install the flow regulating damper
Pay attention to the installation direction of the flow adjustment damper. When the adjustment gate blade is in the almost closed position, the rotation direction of the airflow should be consistent with the rotation direction of the impeller. Otherwise, the efficiency of the centrifugal fan will drop sharply and abnormal vibration will occur.
9. Install the coupling protection device
Install the shaft and coupling protection device, and pay attention that the inner side of the protection device does not rub against the shaft and coupling, and all parts are firmly connected. For centrifugal fans directly driven by couplings, special attention should be paid to the concentricity of the main shaft and the motor shaft during installation. The concentricity tolerance is 0.05mm, and the parallelism tolerance of the two ends of the coupling is 0.02mm.
10. Install oil stations and oil and water pipelines
(1) After the lubricating oil station is fixed as required, install the oil-water pipeline.
(2) The oil pipeline must be pickled before installation, and the inside of the pipeline must be kept clean.
(3) The pipeline layout is reasonable and the direction is correct, neat and beautiful, and the joints are well sealed.
3) Commissioning of the centrifugal fan after installation
1. During the test run of the centrifugal fan, you should carefully read the product manual and check whether the wiring method is consistent with the wiring diagram; you should carefully check whether the working voltage of the power supply to the fan meets the requirements, whether the power supply is out of phase or in the same phase, and the distribution of electrical components. Whether the capacity meets the requirements.
2. There are no less than two people during the test run. One person controls the power supply, and the other person observes the operation of the centrifugal fan. If any abnormal phenomenon is found, stop the machine immediately for inspection; first check whether the rotation direction is correct; after the centrifugal fan starts running, immediately check whether the operating current of each phase is Balance, whether the current exceeds the rated current; if there is any abnormal phenomenon, stop the machine for inspection. After running for five minutes, stop the centrifugal fan to check whether there is any abnormality, and then turn it on again after confirming that there is no abnormality.
3. When the two-speed centrifugal fan is tested, it should be started at low speed first to check whether the rotation direction is correct; when starting at high speed, the fan must be stopped before starting to prevent high-speed reverse rotation, causing switch tripping and motor damage.
4. When the centrifugal fan reaches normal speed, measure whether the input current of the fan is normal, and the operating current of the centrifugal fan cannot exceed its rated current. If the operating current exceeds its rated current, check whether the supplied voltage is normal.
5. The motor power required by the centrifugal fan refers to the larger power required when the air inlet is fully open for the centrifugal fan and the fan box under certain working conditions. If the air inlet is fully opened for operation, the motor may be damaged. It is recommended to close the valve on the fan inlet or outlet pipe during the test run of the centrifugal fan, and gradually open the valve after operation until the required working condition is reached, and pay attention to whether the operating current of the fan exceeds the rated current.
4) Precautions for centrifugal fan installation
1. When the centrifugal fan is connected to the air duct, the air should be as uniform as possible when it enters and exits the fan, and there should be no sudden changes in direction or speed, and it is not allowed to add the weight of the pipe to the centrifugal fan casing; for noise and Where there are strict vibration requirements, noise reduction devices and canvas soft joints to prevent vibration transmission should also be used at the connection between the fan and the pipeline.
2. The pipelines of the air intake and exhaust systems of the centrifugal fan, large valves, and adjustment devices should have separate supports, and should be firmly connected to the foundation or other buildings; There shall be no fixed brackets that hinder thermal expansion and contraction on the connected straight pipe sections.
3. The gap between the air inlet of the fan and the impeller has a great influence on the air output of the fan; during installation, it should be calibrated strictly according to the requirements of the drawing to ensure the axial and radial gap size.
4. For fans driven by pulleys, pay attention to the fact that the outer surfaces of the two pulleys must be in a straight line during installation. Otherwise, the installation position of the motor should be adjusted.
5. For the exposed part of the fan drive and the inlet directly to the atmosphere, the protective cover (net) should be installed before the test run.
6. After the fan is installed, move the impeller to check whether it is too tight or collided.
7. Before the bearing bush is scraped, the axis line of the rotor and the axis line of the casing should be corrected first, and the gap between the impeller and the air inlet and the gap between the main shaft and the shaft hole of the rear side plate of the casing should be adjusted at the same time to make it conform to the equipment technology. document requirements.
8. When the main shaft and bearing bush are assembled, they should be inspected according to the provisions of the equipment technical documents. An interference of 0.03 to 0.04 mm should be maintained between the bearing cap and the bearing pad (measure the outer diameter of the bearing pad and the inner diameter of the bearing housing).
9. When the fan is aligned, the misalignment between the fan shaft and the motor shaft; the radial positioning displacement should not exceed 0.05 mm, and the inclination should not exceed 0.2/1000.
10. For the centrifugal fan assembled with rolling bearings, the different axis degrees of the bearing holes on the two bearing frames can be determined by the flexible rotation after the rotor is installed.
