Chemical centrifugal pumps are generally suitable for chemical plants and chemical industries. Commonly used chemical centrifugal pumps are made of stainless steel, fluoroplastic or carbon steel. The chemical centrifugal pumps of each material are used in different ways, depending on the actual delivery medium. Since the medium delivered by the chemical centrifugal pump is often toxic, harmful and corrosive, and has high temperature or low temperature, the chemical centrifugal pump is required to meet the chemical process requirements, no leakage or less leakage, corrosion resistance, wear resistance, high temperature resistance or low temperature. It can transport liquid in critical state and is reliable in operation.
Analysis and treatment of common fault causes
There are various reasons for the failure of the centrifugal pump. Common types are unreasonable selection, inherent equipment failure, installation, start-up and operation failure. For example, the pump is overpowered due to unreasonable selection; the pump cavitation is severe and the flow is insufficient due to design and manufacturing defects; the vibration and noise of the pump are seriously exceeded due to installation failure; the pump cannot start normally due to the startup and operation failure of the pump and The amount of water is gradually reduced, the filler is heated, and the bearing is overheated.
Abnormal sound or excessive vibration of the pump When the pump is running normally, the small unit consisting of the pump and the motor should be stable and the sound should be normal. If this small unit has noise or abnormal vibration, it is often a precursor to pump failure, and should be stopped immediately to check for hidden dangers.
The cause of the failure may be: unbalanced rotor rotation of the pump or motor, misalignment of the pump and the motor, aging of the wheel apron, unbalanced impeller balance, insufficient rigidity of the pump base, loose anchor bolts, excessive bearing or seal wear Causes eccentricity of the rotor, gas in the pump, no vacuum, improper lubrication of the bearing and packing, excessive wear, worn or damaged bearings, excessive or too little lubricating oil (fat), excessive suction, and impeller inlet Cavitation, when the liquid passes through the impeller, bubbles appear in the low pressure zone, and the bubbles in the high pressure zone collapse, causing vibration caused by the impact. At this time, the installation height of the pump should be lowered, the pump sucks foreign matter, and the impeller is blocked or damaged. Replace the damaged impeller and the vibration caused by the resonance, mainly because the natural frequency of the rotor is the same as the rotation speed of the pump, and resonance is generated.
Overheating of the bearing: If the bearing is found to be hot during the operation of the pump, the cause can be checked in the following items: the pump is not concentric with the electric motor, the coupling is poorly aligned or the axial clearance is too small, the method is to check the alignment and Adjusting axial clearance, insufficient lubricating oil quantity or poor lubricating oil circulation, poor lubricating oil quality, impurities causing bearing corrosion, wear, inflexible rotation, severe bearing wear, and poor bearing scratching, the bearing should be removed again. If the new bearing bush is researched or replaced, and the bearing clearance is too small, the bearing clearance should be re-adjusted or the bearing bushing and bearing assembly should be poorly assembled. The bearing assembly should be checked as required to eliminate the unqualified factors and the cooling water is broken. When the cooling water device and the pump shaft are bent, factors such as the pump shaft should be corrected.
Daily diagnosis of centrifugal pumps
Based on the failure mechanism of the centrifugal pump, the centrifugal pump diagnostic technology accurately collects and detects various signals reflecting the state of the equipment, and uses modern signal processing technology to transform various signals collected in the field to extract information that truly reflects the state of the equipment. Then, based on the fault characteristic information and status parameters that have been mastered, the faults and causes are judged, and the fault development and equipment life are predicted.
Check the official position and seal and condition of the centrifugal pump. Before starting the centrifugal pump, check it manually to see if it can run normally.
After the centrifugal pump enters the working state, the outlet valve is opened in time, and the operating load condition of the motor is observed, and the pressure of the pipeline is observed. Under the condition that the centrifugal pump is in normal operation, the outlet valve is adjusted so that the working index of the centrifugal pump is within the normal control range, so that the centrifugal pump achieves the optimal operating efficiency;
In the normal operation of the centrifugal pump, the bearing temperature is generally not more than 80 degrees Celsius. In the daily temperature control, if the bearing temperature is higher than 60 degrees Celsius, it is necessary to check the oil level of the lubricating oil and the cooling water pipeline. Sometimes it may be due to foreign matter entering the fuel tank; in the working procedure, when stopping the centrifugal pump work, it is necessary to close the outlet valve first, then close the pressure gauge, and finally stop the operation of the motor;
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