Discussion on the Operation of Centrifugal Pumps (II)
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1. In work-related applications involving centrifugal pumps in storage and transportation tank areas (including feeding materials to the facility, loading onto vehicles, and loading onto ships), there are two forms of reflux design: one is back to the inlet； The other option is to return to the material feed tank. What are the differences between these two designs in practical use? I lean towards the latter reflux design; I believe that if the reflux time in the former approach is longer, the temperature of the oil inside the reflux line will rise, affecting the proper operation of the pump. 2. There are two forms of automatic control for reflux: one is FIC ； Another one is PIC. What is the purpose of the different designs for these two? Please share your experiences regarding the above issues. Thank you
1\ I agree with the original poster’s view; these are the terms ‘large reflux’ and ‘small reflux’ that are often used in the operation process. 2\ FIG and PIG: My English isn’t very good, and I’m not an expert in automation, so I’m not entirely sure. As far as I understand it, FIG is an automatic reflux system based on flow rate, while PIG is an automatic reflux system based on pressure at the pump outlet. I have encountered both types of systems for achieving automatic reflux; these days we use flow-rate control more often – when the flow rate falls below a set value, the reflux valve opens. I’m not sure if this is correct; please confirm if I’m right.
1: If it can return to the storage tank, it is generally recommended to do so, as this results in more stable operation. 2: As the name implies, FIC adjusts the flow rate, while PIC adjusts pressure; this depends on the parameters that need to be controlled after the pump. If you need stable flow rate after the pump, then FIC is the appropriate choice.