The self-balancing corrosion-resistant multi-stage pump for chemical industry is a large-scale industrial pump currently used in the chemical industry. The start-up or over-power failure of the self-balancing corrosion-resistant multi-stage centrifugal pump is explained below for your reference.
Reasons for the failure of self-balancing and corrosion-resistant multi-stage pump power machine startup or overpower for chemical industry:
① The speed of the water pump is too high.
②The shaft of the water pump is bent, and the bearing is severely worn or damaged.
③The packing of the pump stuffing box is too tight.
④The impeller of the horizontal self-balancing corrosion-resistant multi-stage pump is stuck by debris or has serious friction with the pump casing.
⑤The pump flow is too large.
⑥ The two drive shafts driven by the coupling are not on the same axis or the drive belt is too tight.
⑦The power of the water pump supporting power machine is too small.
⑧ The pump head is high.
Maintenance method of self-balancing corrosion-resistant multi-stage pump power machine for chemical industry that does not start or exceeds power:
① Try to reduce the speed of the water pump (replace pulleys with different diameters) or change the pump with a lower speed, so that the speed of the water pump matches the speed of the power machine.
②After parking. Disassemble the pump body and check the pump shaft and bearings. If the pump shaft is bent, the pump shaft should be straightened, repaired or replaced.
a. The method of straightening the water pump shaft is to take out the water pump shaft for bench check and find out the bending part. If possible, it can be checked with a dial indicator on the platform or lathe, or the pump shaft can be mounted on a V-shaped iron. Put the V-shaped iron firmly, and then support the dial indicator with the indicator rod pointing to the axis, and then slowly pull the pump shaft. When the shaft is bent, the dial indicator will have a maximum reading and a minimum for each revolution. The difference between the two readings is the curvature of the shaft. There are many ways to straighten the pump shaft. The most simple and easy method on site is the twisting straight shaft method: when the shaft is straight, put the shaft on hardwood (or square iron with copper skin), and the support is required to be larger than the twisted rod. It is soft and has a large contact surface with the twisted bar. With the concave surface facing down, hit it with a hammer and twisting rod. When beating, start from the place with the largest curvature. The range of beating is 1/3 of the circle, which can be drawn on the shaft in advance. The number of hits in the center of the 1/3 arc is more, the more you hit the two sides, the less the number of hits, the first straightening is faster, and then later. In the process of twisting, the change of shaft bending should be measured in time; if the bearing is worn or damaged, the bearing should be repaired or replaced.
b. There are two ways to disassemble the bearing: one is to disassemble on the rotating shaft; the other is to disassemble in the end cover.
Use a special puller to pull the bearing out of the shaft; if there is no puller, use a copper rod with a wedge-shaped end to withstand the inner ring of the bearing in an oblique direction. While hitting with a hammer, move the copper rod along the inner ring of the bearing. , So that the force around the bearing is evenly applied until the bearing is knocked down; in addition, two thick iron plates can be used to clamp the bearing under the inner ring of the bearing, and support it with a cylinder or bracket that can accommodate the rotating shaft, and padded a thick wooden board on the upper end of the rotating shaft Or tap the copper plate to remove the bearing. Because the fit between the bearing hole of the end cover and the outer ring of the bearing is tighter than the fit between the inner ring of the bearing and the shaft. Therefore, when removing the end cover, the bearing should be left in the end cover bearing hole. When disassembling the bearing, lay the end cover with the spigot facing upwards and place a wooden board around the bearing hole of the end cover, but be careful not to resist the bearing, and then use a copper rod or other metal rod with a diameter slightly smaller than the outer edge of the bearing. Hold the outer ring of the bearing and knock the bearing down with a hammer from above.
c. Remove the bearing from the shaft and clean it in cleaning oil (kerosene, diesel, gasoline).
d. First, check the balls, inner and outer raceways for defects such as scratches, cracks or rust spots. Then, fix the inner ring of the bearing to make it rotate. If the bearing is normal, the rotation should be balanced, the speed should be uniform, no noise and stop slowly; if the bearing is abnormal, it will appear as noise, vibration, twisting or sudden stop of rotation. Or when the bearing is pushed by hand, there is a phenomenon such as an impact sound or a feeling of excessive play.
e. Repair method of bearing failure: According to the reason of the bearing failure and the degree of wear, the exchange method and the replacement repair method are often used. The exchange method is that when the wear degree of the bearing does not exceed the allowable value, and it can be used continuously, the load end (bearing wear is more serious) and the non-load end bearing can be exchanged for use; the replacement repair method is when the bearing outer ring or inner ring When the ring is cracked, the balls are broken, the bracket between the balls is broken, the bearing body is severely discolored and annealed, the raceway has deep scratches or rust pits, and the bearing wear exceeds the allowable value, new parts should be replaced.
③Use a wrench to adjust the gland screw of the water pump stuffing box after parking, so that the pump shaft can rotate freely and the amount of water leakage is moderate (generally, the drip rate is 60 drops/min).
④ Disassemble the pump body after stopping, and check the working condition of the impeller. If there is debris on the impeller, the impeller should be removed and the winding should be cleaned; if the gap between the impeller and the pump casing is too small to cause friction, the gap between the impeller and the pump casing should be adjusted to a reasonable value.
⑤It can be eliminated by appropriately reducing the flow rate of the water pump. There are many ways to adjust the flow rate of the water pump, and the following four are more common: one is the variable flow adjustment method, which adjusts the flow rate by changing the opening degree of the gate valve on the outlet pipe of the water pump. Its advantage is that it can ensure the balance between the pump's output and the well's influx, and avoid the forced shutdown due to the suction of the pump's water pump being exposed to the surface of the water. The disadvantage is that it will cause the pump to vibrate and shorten the service life of the equipment. Therefore, it is generally not appropriate to adopt this method to adjust the flow rate. The second is the variable speed adjustment method, which adjusts the flow rate by reducing (increasing) the speed of the water pump. The change of the pump speed can be achieved by replacing the pump pulley with different diameters or changing the speed of the power machine. It should be noted that the drop of the pump speed should not exceed 30% of the rated speed, and the increase should be controlled within 10% of the rated speed. In general, this method should be preferred. The third is the variable diameter adjustment method, which is to reduce the outer diameter of the impeller appropriately to reduce the flow and head of the pump. The fourth is the variable pressure regulation method, which is the method of reducing the number of impeller stages for multi-stage centrifugal pumps to reduce the flow and head of the pump, improve the efficiency of the device, and achieve the purpose of economic operation.
⑥Check the transmission of the drive shaft and belt after parking. If it is driven by a coupling, you can correct the two shafts to be on the same axis by adjusting the installation positions of the power machine and the water pump. If the belt is used for transmission, the tension of the belt should be adjusted reasonably.
a. Coupling installation method
Put the steel ruler on the two halves of the coupling, and then turn the motor shaft by hand to 180° to check whether the two halves of the coupling are the same height. If the height is inconsistent, it should be corrected. The method of correction is to increase or decrease the thickness of the anti-vibration material under the motor frame until the height is consistent. It means that the two machines are in a concentric state, the coupling and the motor can be fixed separately, and the mounting bolts and nuts can be tightened.
b. Correction method for different shafts of transmission shaft
Indicates that the coupling is installed correctly, and the two drive shafts are coaxial;
⑦Reconfigure the power machine according to the technical parameters marked on the nameplate of the water pump to meet the power demand of the water pump.
⑧For the high head of the supporting water pump, the following methods can be used to adjust: One is to appropriately reduce the speed of the water pump to reduce the head and eliminate the overload (overload) of the power machine. This method has a large adjustment range, but the speed reduction should not exceed 30% of the rated speed. For water pumps with belt drive, it can be realized by replacing pulleys with different diameters. The second is to turn the water pump impeller, or replace a smaller water pump impeller to achieve the purpose of reducing the pump head, but the adjustment range of this method is limited. The third is to replace the low-lift water pump that matches the power machine.
