Comparison of Aspen and PRO/II in distillation simulation calculations
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Under the same conditions, when calculating using Aspen11.1 and PRO/II8.0, it was found that the results obtained with Aspen were unreasonable; I would appreciate some guidance from those with more experience. The specific result is: the top of the distillation column is a total condenser, the bottom is a thermosyphon reboiler, and there is a subcooling temperature at the top. In the Aspen results, the temperature of the first tray is not the set subcooling temperature, and the temperature of the last tray is also not the temperature set by the thermal siphon reboiler. In the PRO/II results, the temperature of the first tray is the set subcooling temperature, while the temperature of the last tray is the temperature set by the thermosyphon reboiler. Why does this happen? Logically, in Aspen, the first unit should be a condenser, and the last one should be a reboiler. Is this a defect in the Aspen calculations, or is it some other issue?
I don’t understand; I’ll explain in more detail if there’s a chance
I didn’t explain it clearly enough, sorry! PRO/II 1 39.99999 aspen 1 63.000001 2 63.22771 2 63.22771 19 145.5076 19 145.50757 20 149.3676 20 145. The first tray is the top condenser; it operates in a subcooled state with a temperature setting of 40 degrees. The 20th tray is a thermosyphon reboiler, with a temperature setting of 150 degrees. Through calculations, the results obtained with PRO/II meet the requirements; whereas under the same conditions, the temperature of the condenser in Aspen is not 40 degrees as set, and the temperature of the thermosyphon reboiler is also not 150 degrees as specified. I don’t know what’s wrong with Aspen; are there any special settings that need to be adjusted?
Logically, if the temperature differs significantly from the set value, convergence should not occur. First, check what your error threshold is; it would be best to upload the file so that everyone can take a direct look at it, as descriptions are often not very detailed.
Thank you to the comrades above; I took another look and realized that the temperature shown in Aspen’s logistics results is due to the saturation temperature. :Q
*Jun, hello. You understand, but I don’t yet. Could you explain it in more detail? Also, may I ask: is the feed composition to the reboiler of the Aspen column the same as that of the last tray? Is the gas flow rate also the flow rate at the last plate? The first plate is the total condenser; why are the composition and temperature of the first plate so different from those of the second plate? Please help me understand this; thank you very much. :)