Seeking help regarding the reason for negative pressure at the outlet of the condensate pump and solutions
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This post was last edited by yuchenchf on 2023-2-8 at 10:57. The unit uses a centrifugal pump to transport the condensate generated in the distillation positive-pressure tower, with a heat exchanger installed before the pump. Problems encountered during recent operation: Gas formation inside the pump, resulting in a decrease in flow rate. Open the drain valve on the pump’s outlet pipe; initially, gas is drawn in, followed by steam, and then condensate. Once the condensate flows out, the pump operates normally, but it usually takes no more than 1 hour before gas starts to appear again. I would appreciate some guidance from the experts here.
The problem description is not very clear: 1. Was this centrifugal pump put into operation recently, or has it been in use all along? If it has been in use for a while, did the problem arise only recently? 2. “Open the drain valve on the pump outlet pipe; initially gas is drawn in, followed by steam, and then the condensate.” Is this done while the pump is running? 3. It’s better to have a simple diagram, as that makes it clearer; gas is generated inside the pump, usually due to cavitation. Cavitation occurs when the pump inlet pressure is lower than the saturated vapor pressure at the operating temperature. Please provide a detailed description so that I can give you a solution
It’s mainly due to cavitation; add a tank in front of the pump. It doesn’t need to be very large – about one cubic meter should be sufficient to ensure there is enough water ahead of the pump. Install a low-level sensor in the tank to prevent the pump from operating without water. Make sure to empty the tank properly.
It is recommended to check the system parameters, including liquid level, temperature, pressure, etc., as well as to ensure that the control-related settings are normal. Abnormal conditions such as excessive pressure may occur; it is possible to check whether there are air bubbles in the system pipes and to carry out exhaust operations promptly to ensure the stable operation of the system. At the same time, it is possible to check whether there are any foreign objects blocking the inlet and outlet, or whether the heat exchanger is clean, and to address these issues promptly.