Chemical centrifugal pumps are generally suitable for chemical plants and industries, and commonly used materials for chemical centrifugal pumps include stainless steel, fluoroplastic materials, or carbon steel. The purpose of chemical centrifugal pumps made of each material is different and should be determined based on the actual conveying medium. Due to the fact that the medium transported by chemical centrifugal pumps is often toxic, harmful, corrosive, and has high or low temperatures, it is required that chemical centrifugal pumps can meet the requirements of chemical processes, with no or minimal leakage, corrosion resistance, wear resistance, high or low temperature resistance, and can transport critical liquids with reliable operation.
Analysis and Handling of Common Fault Causes
There are various reasons for centrifugal pump failures, including unreasonable selection, inherent equipment failures, installation, start-up, and operation failures. For example, pump over power caused by unreasonable selection; Severe pump cavitation and insufficient flow caused by design and manufacturing defects; Due to installation failure, the vibration and noise of the pump exceeded the standard severely; Due to pump start-up and operation failures, the pump cannot start normally and the water output gradually decreases, the packing heats up, and the bearings overheat.
When the pump is running with abnormal sound or excessive vibration, the small unit composed of the pump and motor should be stable and the sound should be normal. If there is noise or abnormal vibration in this small unit, it is often a precursor to pump failure and should be stopped immediately for inspection and elimination of hidden dangers.
The possible causes of the malfunction may include: unbalanced rotation of the rotor of the pump or motor, misalignment between the pump and motor, aging of the wheel rubber ring, uncorrected impeller balance, insufficient stiffness of the pump foundation, loose anchor bolts, excessive wear of bearings or seals, resulting in rotor eccentricity, gas in the pump, failure to evacuate, improper lubrication of bearings and packing, excessive wear, bearing wear or damage, excessive or insufficient lubricating oil (grease), excessive suction stroke, cavitation at the impeller inlet, bubbles appearing in the low-pressure area when the liquid passes through the impeller, and bubbles collapsing in the high-pressure area, causing vibration due to impact. At this time, the installation height of the pump should be reduced, foreign objects should be sucked into the pump, and if the impeller is blocked or damaged, the machine should be stopped to clean the foreign objects or replace them. The vibration caused by damaged impellers and resonance is mainly due to the natural frequency of the rotor being the same as the pump speed, Resonance and other phenomena have occurred.
Bearing overheating: If the bearing is found to be hot during the operation of the pump, the reasons can be investigated in the following ways: the pump is not concentric with the electric motor, the coupling is not aligned properly, or the axial clearance is too small. The method is to check the alignment and adjust the axial clearance, the lubricating oil is insufficient or the lubricating oil circulation is poor, the lubricating oil quality is poor, there are impurities that cause the bearing to rust and wear, the rotation is not flexible, the bearing is severely worn, and the bearing is not well scraped. If the bearing clearance is too small, the bearing should be removed and scraped again or replaced with a new one. If the bearing clearance is too small, the bearing clearance should be readjusted or scraped. If the bearing assembly is poor, the bearing assembly should be checked according to requirements, and the non compliant factors should be eliminated. If the cooling water circuit is broken, the cooling should be checked and repaired If the water device or pump shaft is bent, factors such as the pump shaft should be corrected.
Daily diagnosis of centrifugal pump
The diagnosis technology of centrifugal pumps is based on the fault mechanism of centrifugal pumps. By accurately collecting and detecting various signals that reflect the equipment status, and using modern signal processing technology to transform the various signals collected on site, the information that truly reflects the equipment status is extracted. Then, based on the acquired fault characteristic information and state parameters, the fault and its cause are judged, and the development of the fault and the service life of the equipment are predicted.
Inspect the circuit, seal, and condition of the centrifugal pump, and manually check whether it can operate normally before starting the centrifugal pump;
After the centrifugal pump enters the working state, open the outlet valve in a timely manner, and observe the operating load of the motor and the pressure of the pipeline. Under normal operation of the centrifugal pump, adjust the outlet valve to ensure that the working indicators of the centrifugal pump are within the normal control range, so as to achieve the best operating efficiency of the centrifugal pump;
In the normal operation of the centrifugal pump, the bearing temperature generally does not exceed 80 degrees Celsius. In daily temperature control, if the bearing temperature is found to be higher than 60 degrees Celsius, it is necessary to check the oil level of the lubricating oil and the condition of the cooling water pipeline. Sometimes, it may also be due to foreign objects entering the oil tank; In terms of work procedures, when stopping the centrifugal pump, it is necessary to first close the outlet valve, then close the pressure gauge, and finally stop the operation of the motor;