The centrifugal pump return line is used for stirring purposes
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The medium is a 1% aluminum chloride solution – can a centrifugal pump be used? This solution tends to precipitate, so I want to add a return line at the pump outlet (returning it to the tank) to facilitate mixing. Would 30% of the diameter of the external pipeline be sufficient for this return line? Are there any other things to keep in mind?
The pump outlet return line is used as a protection line for the minimum flow rate of the pump; this minimum flow rate is typically the lowest value allowed by the pump, as specified by the pump manufacturer. As for the return pipeline playing a stirring role? I think the effect is minimal. Our storage tank material discharge pumps also have similar pipelines, and we have tried to take samples to analyze the quality of the mixture, but the results were not particularly satisfactory. Mixing is not necessarily thorough, let alone stirring to prevent sedimentation. It would be better to create a mixing device or consider the storage temperature aspect again.
That’s indeed the case. Is it okay to use only a stop valve on the pipeline with the minimum flow rate?
The solution inside the tank has properties similar to water, with low viscosity; therefore, pump circulation is still a consideration. So, it would be possible to use an equal-diameter tee at the pump outlet to enable both circulation and external transfer; additionally, installing a static mixer in the circulation pipeline – is this approach feasible?
The pump head under circulation and during external transfer is not equal, and the difference between them can be significant. If the difference in head between external transfer and circulation is small, a throttle valve can be installed at the outlet for flow regulation; it is also possible to use a static mixer in the circulation line. However, if the difference is large, and such a piping design is still required, it is necessary to install a flow control device. In my opinion, this setup is not suitable when the difference is large；
Can it be mixed well when the difference between Yang and Cheng is not significant? “Before mixing, it should be in a multiphase separated state. The minimum flow rate line is there to ensure the safe operation of the pump; it can only impact the liquid at the pump’s inlet, but it cannot ensure uniform mixing.