Regarding the setup of the return pipeline for shielded pumps
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I’d like to discuss the issue of backflow in shielded pumps； 1. Throttling orifice plate type: in this case, does the pump manufacturer need to specify the minimum flow rate, after which we select the flow rate corresponding to the throttling orifice plate? Moreover, the minimum flow rate under such conditions must be added to the pump’s flow rate, resulting in a larger pump size being required. 2. Control valve type – is this the most favorable option in terms of both pump protection and selection?
In both cases, the requirements are met; what is specified in the national standards is the first case. However, although this meets the equipment requirements, it does not satisfy the process requirements. In some distillation towers, where the reflux flow rate fluctuates significantly and the reflux ratio often needs to be adjusted, it may be necessary to divide the flow at the outlet of the reflux pump at the bottom of the reflux tank into at least three streams – one stream for reflux to the distillation tower, one stream for use within the reflux tank, and another stream for external discharge. Three control valves are used to balance these three streams, with the goal being to meet the process requirements; all of these settings are designed to fulfill the objectives of the process