The resistance levels of various types of flow meters
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A problem was encountered in the project: the height difference between the reflux tank and the reflux liquid inlet of the distillation tower is only 2.5 meters, and the client requires flow control even though gravity flow is possible. Given such a small height difference, it’s possible that even the resistance of one flow meter cannot be overcome. So I came here to discuss this – can those who are experienced in this area tell me which type of flow meter has the lowest resistance? Which types of flowmeters have greater or lesser resistance? Or where can I obtain relevant information? Thanks for the exchange.
Electromagnetic flowmeters, and other flowmeters that are not of the throttling type
It’s a bit difficult, but it’s necessary to carefully calculate the piping layout: place the orifice plate at the lowest point of the pipeline, and the control valve downstream at the inlet of the tower. To ensure that flashing does not occur inside the orifice plate, a differential pressure of 10 KPA can be used as a reference; by setting a larger orifice ratio, flashing should be prevented. Control valves are basically full-bore. The same principle applies to the orifice flow measurement of the reboiler steam condensate: it is the pressure difference across the equipment that provides the resistance drop for the flow meter (+ pipes), or is it the saturated condensate? For large supercoolings, vortex flow meters can be tried; those near saturation cannot be used. Also, the electromagnetic effect on the upper floor will work, provided it is a conductive liquid.
Thank you to the two people above for their guidance; I plan to first calculate the pipeline resistance carefully before deciding which type of flow meter would be suitable