If the HYSYS simulation tower product does not meet the requirements, how should it be modified?~
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I used HYSYS to simulate a propylene-propane distillation column; basic parameters such as temperature, pressure, number of trays, and feed position were entered. After running the simulation, it was shown that convergence had been achieved, but the product quality did not meet the requirements – the top product did not satisfy the specified standards, while the bottom product exceeded the separation requirements. I then reduced the feed position and increased the reflux ratio, but the purity of the top product actually decreased, whereas the purity of the bottom product remained unchanged. It’s really frustrating. . . I’d like to ask the experts here: how should I adjust the parameters? ? Is it because my previous setup was incomplete, lacking certain conditions? ? And how should I upload attachments? ? I uploaded it in .hsc format, but it says the format is incorrect and won’t allow uploading. . . This post was last edited by floweronsun on 2009-4-15 14:51]
Could you send your simulation file so everyone can take a look? Don’t forget to specify the desired simulated results!
But I’m only in the second grade now; it seems I can’t upload it. What should I do? Is there any other way? ?
Since your model focuses primarily on product quality, you can remove a parameter that isn’t very important from the list of degrees of freedom and replace it with a specification for product quality. For example, if you require 80% purity for the propylene, and you don’t care about the reflux ratio, then set Spec Comp Frac to 0.8, check the \"Active\" box for this parameter, and uncheck the \"Active\" box for the reflux ratio – this way the model will calculate the reflux ratio on its own. Without specific parameters, one can only try different values... Please feel free to correct me if I’m wrong.... This post was last edited by scbnmao on 2009-4-16 at 10:38.]
May I ask, which two parameters are generally chosen as the degrees of freedom for a distillation column? ? I’m a beginner and don’t quite understand~ Please give me some guidance~~
Since I haven’t designed many distillation columns, I’m not sure which parameters are typically chosen. From the examples I’ve seen, distillation columns have different numbers of degrees of freedom depending on their structure (such as the number of side draws and whether complete condensation occurs). If there are no values specified in the parentheses, then there are two degrees of freedom. To get back to the main topic, in the examples I’ve seen and in the columns I’ve designed, there aren’t fixed parameter specifications; it depends on the purpose of analyzing the model. For example, if you want to know parameters such as the reflux ratio and product yield under conditions of producing qualified products, then you should specify the product quality. If you want to know the product quality at a certain reflux ratio, then obviously the reflux ratio should be the specified parameter. And if you already know the detailed parameters of the column, such as the top temperature and reflux ratio, then you can specify those as well. In short, it depends on what you’re interested in, which determines which parameters you need to specify, as long as you end up with the desired results... Regarding convergence, it seems that, maybe, perhaps—at least in the columns I’ve simulated, specifying the product quality is the easiest way to achieve convergence. PS: Parameter specifications can be added through Specs->Column Specification->add; you can add whatever you need. I’d appreciate any feedback from everyone....
I tried it today, and it seems that the reflux ratio and the top product cannot be converged – is it because these two variables cannot be set simultaneously? ?