Gas is present in the inlet pipeline of the centrifugal pump
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Our multi-stage centrifugal pump has two plate exchangers connected in series at its inlet. We are now testing the pump, and we noticed gas present at the pump’s inlet. The gas was removed by using the exhaust valves on the pump’s inlet and outlet as well as those on the plate exchangers. When the pump was started, it operated normally at first; however, after 2 to 3 minutes of operation, the flow rate increased from 50% to 80%, and the pump’s pressure dropped. At the same time, the pump began to vibrate, and the noise level increased significantly. Stop the pump immediately, open the pump inlet vent valve and the heat exchanger vent valve to allow gas to escape; it is preliminarily determined that there is gas in the inlet pipeline, resulting in insufficient inlet flow. I hope the experts here can offer some guidance.
Based on the situation you described, the centrifugal pump is showing abnormal phenomena such as reduced pressure, increased vibration, and heightened noise during operation. This situation is usually related to the presence of gas and insufficient inlet flow. It is recommended to take the following actions: 1. Based on your initial assessment, first check whether there is gas in the inlet pipeline and remove it using the exhaust valve. 2. Check whether there is an adequate supply of liquid at the pump’s inlet; insufficient inlet flow can cause excessive oscillation and noise during pump operation. 3. Check whether the pump’s inlet pipeline is properly designed, and whether there is any liquid backflow, air ingestion, or gas-liquid mixing – conditions that can all lead to unstable pump operation. 4. Check the operating status and cleaning condition of the heat exchanger plates; abnormal operation of the heat exchanger or inadequate cleaning can also lead to unstable pump performance. 5. If the problem still cannot be resolved, it is recommended to contact professional pump maintenance technicians for handling. In summary, during the use of pump equipment, paying attention to exhaust, keeping the inlet pipes unobstructed, and designing the inlet pipes properly can effectively prevent problems from occurring while the pumps are in operation. .
First, it is necessary to identify the source of the gas. 1. What is the state of the medium on the other side of the plate heat exchanger? If the pressure on the fluid side is higher than that of a liquid, there may be a risk of air leakage in the heat exchanger. 2. What is the saturation temperature corresponding to the inlet fluid pressure? Is it \"cavitation\" caused by vaporization due to high temperature or low inlet pressure??? For reference.
1. The pressure drop across the plate exchanger is too high, resulting in low pressure at the pump inlet. 2. The temperature of the medium at the pump inlet is too high, resulting in vaporization and evacuation. 3. The pump inlet filter is partially clogged.
Is the gas discharged after stopping the pump air or process gas? If it is process gas, the pump experiences high vibration and noise; if the pressure is lower than normal, it is likely due to cavitation. If it enters the air pump, it will run idle, and the vibration and noise will not increase.