Why are there two controls for the air fan here?
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Can’t we just use pressure control directly? What’s the purpose of flow control?
What are the process requirements? It might be that the manufacturing process requires this, or it could be that the designer has opted for a design with enhanced functionality
It should be that the minimum flow requirement is lower than the fan’s own performance
This is indeed not a requirement of the manufacturing process, but rather a consideration for equipment safety; the technical name for this pipeline is an anti-surge line.
I have never seen this kind of process control before, but based on the explanations from technicians on other floors, it seems that the fan equipment has specific requirements regarding flow rate. In some cases, those requirements cannot be met, which leads to a pressure buildup and issues with the operation of the equipment. This is likely related to the specific conditions of the process as well as the characteristics of the equipment itself. It has nothing to do with the manufacturing process; it’s used to protect the equipment. Under automatic control, it should be that when the inlet flow is below a certain level, the outlet valve is opened to ensure that the fan equipment operates at its minimum level. I’ve never seen this before; it’s just my personal understanding: lol
Flow control is based, on the one hand, on process requirements; on the other hand, the piping system associated with the equipment has a surge flow range, and it is necessary to stay outside this range in order to prevent surging in the centrifugal fan
It’s a fan driven by an industrial-frequency motor, right? The flow rate is related to the fan’s surge phenomenon, while the pressure is related to the process conditions
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