Control at the outlet of the reflux pump in the overhead separator of the distillation tower
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I have a question: at the outlet of the reflux pump in the top separator of a distillation tower, there are two paths; one path is for reflux, and flow control valves are used to regulate this flow. The other branch is the separator level control regulating valve. If control is applied to both branches at the pump outlet, will they affect each other, making it difficult to control?
Is the return branch pipe a flow control system? Should we still use reflux flow to control the tower top temperature? These two control loops influence each other. Assuming the pump speed remains constant, the flow rate at the pump outlet is constant; if the flow rate in one of the two branch pipes changes, the flow rate in the other pipe must also change (as the sum of the flow rates in the branch pipes remains constant). However, the operating frequencies of the two control loops differ; the level control system is slower than the flow control system (assuming it is a simple flow control system), so the connection between the two loops is relatively weak.
It is necessary to know what the characteristics of your pump are; a simple flow diagram is required for that. As long as it has been designed, one just needs to understand its principles. Standing in front of the schematic diagram that you can see, randomly selecting a section to ask questions makes it difficult to provide accurate explanations and discussions. With all due respect.
Isn’t this the most common control method? One FC, one LC.
Check the pump’s load capacity. If the output flow rate of the controller is greater than the maximum flow rate of the two circuits, there will be no issues with control ； If the pump’s output only meets the normal flow requirements of the two circuits, control systems will affect each other when the load fluctuates.