Reasons and Countermeasures for Vibration of Centrifugal High Pressure Oilfield Water Injection Pump
Affected by the corrosion of transporting corrosive media, the frequency of failure of centrifugal high-pressure oilfield water injection pumps is very high. In the long-term use and maintenance of water injection pumps, it is found that the most important factor affecting pump efficiency and service life is the vibration of the centrifugal pump. Take the DFP self-balancing centrifugal high-pressure oilfield water injection pump as an example to analyze the causes of vibration and countermeasures.
DFP self-balancing centrifugal high-pressure oilfield water injection pump
The cause and countermeasure of vibration of centrifugal high pressure oil field water injection pump
Assembly reasons and countermeasures
(1) Static imbalance is caused. In the rotor of a multi-stage centrifugal column water pump, there are many components, such as the DF120-150×10 type. The composition of the rotor includes balance disc, shaft sleeve, pump shaft, stop sleeve, and impeller Wait, there are 10 parts in total. If the high-rotation speed is 2980r/min and the rotor part is statically unbalanced, then the dynamic unbalance will inevitably be biased, so pump vibration occurs. The appearance and principle Vibration occurs in the front and rear bearings. In response to this situation, in the work of assembling the pump, relying on the professionalism of the staff, special equipment is used to implement static balance tests on the various parts of the rotor, so that the unbalanced bias will disappear here, and the parts are in their own balance. The state of the water injection pump will not cause any vibration due to the heavy weight, ensuring its smooth operation.
(2) Due to dynamic imbalance, after the assembly of the rotor components, errors occur from time to time due to too many components, so the dynamic balance test is indispensable, and the weight of the rotor can be removed to overcome the problem of heavy weight during pump operation. And the phenomenon of unbalanced vibration occurs. Someone has done corresponding tests on both pumps, and found that if the static balance experiment is simply carried out, then it is necessary to ensure that the vibration of the front and rear bearing bushes exceeds 0.07m, and the vibration of the dynamic and static balance test is kept within 0.01m. From this experiment It can be seen that the operation of multi-stage pumps will have various error accumulations, so the necessity of using the dynamic balance test machine is determined. In short, the combination of dynamic and static balance tests can greatly improve the accuracy of rotor balance. .
(3) The accuracy of the rotor assembly results in vibration caused by the friction of the seal ring between the rotor and stator, and 0.07m is the control value of the component's axial degree. In order to prevent vibrations that exceed the control value, it is necessary to prevent contact Friction, otherwise it will affect the normal operation of the multi-stage pump. There is only one solution to this situation, and that is to return to the factory to disassemble and re-check the accuracy of the rotor.
(4) Due to the different shafts of the pump, the motor shaft and the pump shaft are not in a line, and vibration will occur during the high-speed rotation of both. This is a relatively common form of vibration. The solution is to re-adjust.
(5) As a result of the improper lift of the rotor, it is necessary to ensure that the rotor in the stator does not generate friction. Under normal circumstances, this vibration is not too large. Pay attention to adjust the two when assembling the pump.
(6) The back cap of the rotor shaft is loosened. Generally speaking, the looseness is nothing more than the following reasons. For example, the outlet valve and the outlet check valve are damaged at the same time, the back cap is loose, or the motor cable is reversed. It may be that the assembly did not meet the tightening requirements. At this time, it is necessary to notify the staff to deal with it on the spot to prevent more serious damage to the pump.
Vibration reasons and countermeasures during use of centrifugal high pressure oilfield water injection pump
The vibration of the centrifugal high-pressure oilfield water injection pump is mainly manifested in the presence of foreign matter in the water, the balance gap is too small, the balance plate is not opened, the balance sleeve has friction, etc. If these conditions are not discovered in time, it will cause damage to the balance system and timely maintenance work Very important. The following analyzes the vibration during use:
(1) Due to cavitation, during the operation of the centrifugal pump, the lowest pressure is located at the inlet of the blade, and the impeller liquid at this time does work and quickly increases the pressure. The liquid vaporizes at the inlet of the blade, and bubbles appear. The liquid flows together from low to high air pressure. The bubbles under high pressure will condense or rupture. The surrounding liquid will occupy the space of the original bubbles at a higher speed. The resulting pressure is very high and the number of impacts increases. This is a very common problem in centrifugal pumps, mostly due to the large deviation between the operating point and the rated flow, so the water inlet section will vibrate and cause current fluctuations. The solution can be to store water to reduce hydraulic loss or try to avoid the deviation between the working point and the rated flow.
(2) The guide vane is loosened. During the operation of the pump, the guide vane will be loosened due to constant opening or corrosion by water. At the same time, there will be some abnormal sounds. In this case, the guide can be repaired, reinforced and replaced. Ye's way to solve it.
(3) Foreign matter is blocked. The suction of foreign matter at the pump inlet filter will block the suction port of the impeller, affect the water intake, and cause the balance system to malfunction, so friction between the balance sleeve and the balance plate may occur. The harsh sound can be solved by dismantling and repairing.
(4) The main equipment of the unit includes the motor due to the failure of the motor. If the magnetic force is unbalanced in the motor, or other electrical systems are out of adjustment, it is easy to cause vibration. The solution is to maintain and repair the motor in time.
(5) Excessive main line pressure is caused. If the main line pressure exceeds the pump outlet pressure, it will cause the pump to fail to pump water. After a long period of operation, the balance system will be damaged. This situation can be adjusted The pressure is resolved.
