What are the causes of abnormal vibration found in chemical centrifugal pumps?

　　Chemical centrifugal pump is a common industrial pump, widely used in petroleum, chemical, metallurgy, electric power and other industries. However, in the process of use, chemical centrifugal pumps may appear vibration problems, which will not only affect the normal operation of the pump, but also lead to equipment damage and safety accidents, therefore, it is very important to understand the causes of vibration of chemical centrifugal pumps and their solutions, the next step we explain the causes of vibration of chemical centrifugal pumps

　　I. Pump shaft bending

　　Machine pump shaft is with the impeller fixed on it or rotor rotation, due to the weight of the impeller and rotor, especially the large machine pump, when the machine pump stops working for a long time, so that the machine pump shaft in a direction of force, resulting in shaft bending. Shaft bending of the pump in operation will cause the impeller and other transmission imbalance, resulting in friction between the impeller and the shell, resulting in vibration of the pump. The solution is to disk once every 8h, each time according to the same direction of the shaft rotation of 120 degrees.

　　II. Bearing problem

　　1. Bearing “running outside edge”.

　　Due to the poor quality of bearing assembly, the pump after a long period of operation, there will be bearing “run outside edge” phenomenon, resulting in bearing temperature rise, produce noises, rotation. The solution is: (1) the bearing bracket welded on a layer of metal, and then turned to the appropriate size, reassembly; (2) such as bearing clearance is large, can add thin copper, so that the bearing outer edge of the static fit to achieve the specified value.

　　2. Bearing wear

　　Currently purchased from the market bearing more or less have some quality problems. Mainly ball size, hardness, clearance, etc., it is difficult to ensure the quality of maintenance. Bearing wear is generally accompanied by heat and abnormal sound, and in serious cases, the pump jamming occurs. Therefore, the bearing abnormalities found should be replaced in a timely manner.

　　3. Shaft tile clearance is too large

　　This situation often occurs in the use of sliding bearings in large and medium-sized pumps, if the shaft tile clearance is too large, it is easy to make the shaft loose, so should be adjusted in a timely manner shaft tile clearance.

　　Three. Coupling problems

　　The role of the coupling is mainly to connect the pump and motor to rotate together and transmit torque, the problem has the following two points, one is not the same heart, some large pumps after a period of time, it will change, if there is a different phenomenon, can only be shut down and re-find the right; two is the coupling used by the rubber ring, plum rubber skin, such as easy to be damaged, will be damaged to change the rubber ring can be restored to normal.

　　Four. Liquid channel is not smooth

　　When the pump is running, due to the liquid channel is not smooth, resulting in hydrodynamic shock and cause the pump vibration. The main reasons are as follows.

　　1, the exit valve opening is too small

　　Centrifugal pumps, especially high-head, large-displacement pumps in the flow of small hours is easy to produce a degree of vibration, when the flow of large open valves normal, the vibration will disappear.

　　2、Pump suction end of the pipeline into the air or debris

　　Inlet end of the bottom valve and strainer equipped with a transfer pump, in the early trial run of the fluid is too dirty or viscosity is too large, prone to cavitation, accompanied by vibration, serious pumps can not work properly. In order to eliminate this phenomenon, it is best to install a negative pressure gauge at the inlet end of the pump, in order to observe the negative pressure changes at any time, so as to accurately determine the changes in the inhalation piping, and clean up the bottom valve and filter in a timely manner.

　　3. Air pockets in the outlet pipe

　　Even if there is a more thorough air discharge when the pump is turned on, it is difficult to put clean, easy to form air pockets during operation, so that the pressure fluctuations in the pipeline. The solution is to install the emptying point as high as possible, and pay attention to the individual local exhaust treatment. In addition, in operation, start the pump first with a small displacement of water, so that the trunk pressure slowly rise, can also make the pressure fluctuations are reduced.

　　V. Problems to be noted in maintenance

　　In the process of maintenance, it should be operated in strict accordance with the regulations, and should pay attention to the following points.

　　(1) When the pump is overhauled and installed, the pump body, pump shaft and pump and motor level should be re-fixed to meet the specification requirements, otherwise the machine pump will be unbalanced during operation, causing vibration.

　　(2) pump repair and installation of import and export piping, due to changes in pipeline displacement, especially the new commissioning of the pipeline, the first time to dismantle the import and export flange, the relative displacement of the flange is very large. The solution is to fix the pump first, then find the right position, then cut off the flange on the import and export pipeline so that it can be aligned with the flange on the pump body first, install the connecting bolts and tighten them, and then connect the import and export pipeline with this flange.

　　(3) According to the requirements of the maintenance regulations, when the pump is aligned, copper sheets should be used as shims, and there should not be more than 3 shims at most in one place, otherwise it is difficult to ensure the smooth operation of the pump.

　　(4) When replacing the pump, the hole in the base of the pump is often enlarged because the base of the pump does not match the foundation foot bolts. The more times it is replaced, the larger the hole becomes, which finally leads to the impossibility of tightening.

　　The above are some of the reasons for pump vibration, not complete and not deep enough, but also need to be improved in the future work.