Questions about gas valves in Aspen adsorption
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I saw in the built-in pressure swing adsorption cycle model that the gas valve can be controlled using values of 0, 1, 2, 3 – different methods are available for control. I’m not sure which one to choose; I hope someone experienced can advise me. Thank you
There are explanations later; they represent off, flow rate, CV, opening degree, if I’m not mistaken
Yes, but I don’t know which mode to choose for general modeling, and how to determine the CV value. Could you explain it a bit? Thank you
The first three are used more frequently; \"close\" and \"flow rate\" are easy to understand. CV is useful during the pressure equalization process. The CV value represents the flow rate per unit time, which is equal to the pressure drop across it; for example, if CV is set to 0.2 kmol/s/bar, it means that the flow rate is 0.2 times the pressure drop per second.
I can roughly understand what this thing means. I’m currently watching that video tutorial on the four-step PSA process for nitrogen and oxygen. What I don’t quite understand is why he sometimes chooses 2:Flowrate, and other times uses 3:CV. Then I’m not quite sure how the value of his Cv is determined. Could you please give me some advice? Thank you
I haven’t watched any videos on this, and I’m not involved in adsorption processes either. But I think that, for example, during the pressure increase process, if a fixed flow rate is used to raise the pressure, then the increase in pressure within the adsorption tower will be constant. On the other hand, with CV control, the pressure in the adsorption tower increases rapidly at first and then more slowly over time. Whatever method is used in actual production, that’s what should be set in the software!