Sensitivity analysis issue of the radfrac module in Aspen
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When performing a sensitivity analysis on the radfrac module, I want to use the liquid feed flow rate and the molar concentration of PZ in the liquid feed as independent variables, while using the molar fraction of CO2 in the exhaust gas as the dependent variable. I encountered two problems: one is that, after selecting a range for the liquid phase feed flow rate (L/h), setting an appropriate spacing between points, and determining the number of points to use, an error always occurs at the maximum value of this flow rate range in the simulation results; this error persists regardless of whether I increase or decrease the flow rate range. But strangely, I set it to 6 points, yet an extra point appears (7 points in total), causing an error; the first 6 points are all normal, as shown in the diagram. The second is that the components in my feed liquid have a specified molar concentration (mol/L); the total volumetric flow rate (L/h) is chosen, and water is set as the solvent. I want to use the molar concentration of PZ in the components as a variable, but it cannot be found in the sensitivity analysis categories (only mol/h of molar flow rate is available). Therefore, I calculated the corresponding molar flow rate by multiplying the different volumetric flow rates of the liquid feed by the molar concentration of PZ, but the system indicated that the input was not valid or gave an error message. I would like to ask whether the molar concentration in the components can be set as an independent variable in Aspen? What is the cause of the above error?
Regarding the first issue, it is recommended that you check whether your traffic range is set correctly, and whether the step size used for equal division is too large or too small, which may be causing the error. You can try manually adjusting the position of the maximum point to see if that resolves the issue. Regarding the second question, in Aspen, only molar flow rate can usually be selected as the variable for sensitivity analysis. You can consider calculating the corresponding molar flow rate by setting different volumetric flow rates of the liquid feed and the molar concentration of PZ, and then using this molar flow rate as the independent variable for sensitivity analysis. If an error occurs during execution, it is recommended that you check again the correctness of the input parameters, such as whether the units match. If that still doesn’t work, you can try contacting Aspen’s official technical support. .