What can we do to avoid the cavitation of the centrifugal pump?
About half a year after the completion and operation of a pharmaceutical factory, it was found that the production water of the whole factory was insufficient, resulting in the shutdown of the whole factory. In view of this situation, the centrigual pump in the plant was inspected and analyzed. It was found that four pumps in the riverside water pump house were subject to different degrees of cavitation, the most serious one was the main the centrigual pump, the front and rear cover plates of the impeller were broken through more than 100 holes, the largest hole area was up to 5cm, and the other three impeller of the centrigual pumps were not broken through many holes, but the erosion was very serious. It is obvious that insufficient water production is caused by cavitation loss of the pump. Why have these the centrigual pump been damaged to such a serious extent in only half a year?
First of all, it is found that the water level of the Yangtze River in that year was very low, and the actual installation height of the pump exceeded the allowable installation height, which is the main cause of pump cavitation. When installing the the centrigual pump, the lowest water level of the Yangtze River over the years was not considered;
Secondly, in such a short period of time, the severity of the damage to the main the centrigual pump shows that there are other reasons. After further inspection, it is found that a plastic bucket for construction is stuck in the inlet pipe of the main the centrigual pump, which causes the inlet resistance of the pump to be too large, so that when the pump is put into use at the beginning, the water level is not lowered to the lowest water level at that time, it is prone to cavitation. However, the operator has not found that it is just increased Pump was added to increase the flow, and then the water level of the Yangtze River decreased, which caused cavitation of other standby the centrigual pump;
After the analysis of the impeller materials by mechanical experts, it is found that the materials used for the impeller of the the centrigual pump do not meet the requirements. All of the above causes make the pump seriously damaged in a short time.
Example 3: during the operation of a vacuum tower, the the centrigual pump on the top of the tower is cavitating. The return tank is on the 6m platform, with a cavitation allowance of 2.5m. There are about 10m pipelines and two valves in the middle. From the point of view of design calculation, cavitation should not occur, but this kind of problem occurs on site. Where is the problem?
According to the design requirements, as long as the effective cavitation allowance of the pipeline is 1-1.5m larger than the necessary cavitation allowance of the the centrigual pump, the centrigual pump will not suffer cavitation. However, the necessary cavitation allowance of the pump is related to the flow. The data provided by the pump manufacturer is the necessary cavitation allowance under the rated flow. If the flow increases, the necessary cavitation allowance will increase accordingly. Therefore, it is necessary to check whether the necessary cavitation allowance of the pump increases under the actual working condition from the performance curve according to the actual operation situation.
In addition, the resistance of the the centrigual pump inlet section should also be calculated according to the actual working conditions, in order to obtain the accurate effective cavitation allowance. This is to verify the possibility of cavitation. First, check whether the inlet pressure of the pump is sufficient; whether the inlet temperature of the pump is too high; whether the rotation speed of the pump is too high; whether there is any deviation between the working condition of the pump when cavitation occurs and the working condition allowed by the pump characteristic curve. If there is no cavitation after calculation, the blockage of inlet pipeline or valve will increase the inlet resistance and reduce the effective cavitation allowance, which may lead to cavitation.
Based on the above analysis of the process and mechanism of centrifugal pump cavitation, we can see the causes of centrifugal pump cavitation and our solutions. These solutions can be summarized as three points: the first point is to improve the structural design of the pump itself and its connecting pipelines, the second point is to improve the cavitation performance of centrifugal pump through auxiliary equipment, and the third point is to change The external installation and service conditions of the the centrigual pump enhance the anti cavitation performance of the the centrigual pump.
In the actual production and operation, it is also necessary to strengthen the maintenance of the centrifugal pump, timely replace the damaged parts, reduce the damage caused by cavitation of the centrifugal pump, so as to prolong the service life of the pump and improve the operation efficiency of the pump. The staff must be responsible for the installation and use of the centrifugal pump, find out the cavitation phenomenon in time, analyze the causes and take corresponding measures, so as to protect the continuity of production, reduce the consumption of materials and save human and material resources.
Hope the information is useful for you and avoid the Cavitation of centrifugal pump during usage?