On the selection of liquid hydrocarbon pumps for cryogenic recovery systems
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Medium: Isopentane, ethylene, butylene. Inlet temperature: -30~40°C. Inlet pressure: around 0.3 MPa. Designed flow rate: 200 kg/h. Back pressure: 2.4 MPa. Diaphragm pumps are currently being used; previously, a flow rate of around 50 kg/h was achievable, but now there is no flow at all. Question: 1. What type of pump is suitable for use when there is a risk of vaporization at the inlet? 2. How to adjust the operating conditions to meet the operational requirements?
This phenomenon occurs when the external temperature gradually rises; a higher temperature of the medium facilitates vaporization, which leads to a decrease in the system’s NPSHa, and the pump may also suffer from cavitation. To solve this issue, attention should be paid to insulation for the pipelines; as for the pumps, they can be replaced with barrel-type cryopumps, which are buried underground and are less affected by air temperature and sunlight. Buried underground at the same time, effectively increasing NPSHa.