How should I understand this temperature-flow linkage in the graph?
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I would like to ask the experts to explain in detail how to understand the interconnection between the tower top exit temperature and the tower top feed flow rate shown in the diagram. Do TIC, FT, FY, and FTC all need to be connected to the DCS? Can it be understood that the operating parameters of the FY controller are determined by TIC and FT values? But how are these values determined? Is it based on process requirements? Then, each party considers whether to use proportion, integration, or differentiation for temperature and flow rate Or should flow be adjusted proportionally and temperature be controlled via integration to stabilize the feed rate? I hope the experts can give me some guidance; thank you!
One uses a single loop, and the other uses a cascade configuration
In cascade control, the control valve first regulates the flow rate; when automatic mode is activated and cascade control is used, the control valve indirectly controls the temperature, with the flow rate serving as the intermediate variable