Pump selection issue
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Engineering example: Project A: Both the refrigeration unit and the chiller tank are located on the 0-meter level; the liquid flows from the hot side of the chiller tank, through the pump, to the refrigeration unit, and then to the cold side of the chiller tank； The pump selected on site is a single-suction pipeline centrifugal pump with a head of 14 meters, a power rating of 11 kW, and a flow rate of 120 cubic meters per hour. The equivalent length of the pipeline is 60 meters ； The refrigerant used is Glacial Age Coolant 4. (Viscosity: 12.5 cp at 20°C; Density: 1.105 g/cm3). Test run results: After the pump was started, the flow rate was normal for a short period of time, but it became very low afterwards. The gauge pressure of the pump is 0.16 MPa. Is it because of President Zhou? This is the first time I’ve encountered this problem. One pump is in operation and one is in standby. Both pumps showed the same problem when tested. Is the pump too small? I would like to choose: to reselect the model as ISG125-16B, with a flow rate of 136 m3/h, a motor power of 15 KW, and a head of 25 m. I’m not sure if it will work. I would appreciate some guidance from the experts:
Why replace the pump? Can’t we just use an impeller of type A or the original one?
Is it possible that your Y-filter is clogged, with too much dirt inside it? It is recommended to check and clean the filter elements. Also, does the V-4001 tank ahead of you have a vent valve, or something to ensure that the pressure inside the tank remains above atmospheric pressure?
Upon calculation, the pump’s head is basically sufficient (assuming a pressure drop of 50 kPa in the system). It is recommended to check the pump pre-filter and the flow setting value of the flow control system. https://bbs.hcbbs.com/thread-1764877-1-1.html Additionally, the design of this process isn’t very good; it is recommended to eliminate V-4001 and add a small high-level tank (0.5–1 m3 will be sufficient). This tank should be installed at a height higher than that of all users. This approach allows for full utilization of the potential energy, and it also results in a smaller amount of liquid stored in the system.
Firstly, the head is higher than the design value while the flow rate is lower than the design value; according to the characteristic curve of centrifugal pumps, such changes are normal, indicating that the probability of damage to the pump itself is low； Then, if it operates normally for a period of time, this indicates that the piping is in good condition; if the medium is clean, there will be no blockages ； I see on your flow diagram that there is a temperature-controlled interlocked flow control valve; it’s very likely that changes in the system’s process temperature triggered the operation of this flow control valve, resulting in an increase in system resistance and a decrease in flow rate
Can the V4001 level meet the pump’s flow rate? V4001 has a capacity of 35 cubic meters, while the pump has a capacity of 120 cubic meters
It passes through a heat exchanger, and there is a temperature-flow interlock there, which may have triggered the interlock control