Selection of Operating Specifications in Aspen Plus when using RadFrac for simulation
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As the title suggests, I found that using the heat load at the tower bottom makes it easier to achieve convergence of the process compared to using other parameters (such as the output from the tower bottom or the output from the tower top); I’m not sure why this is the case. Throw a brick here first!
It seems that the program converges primarily based on heat balance; just as in a crude oil distillation tower, adjusting the heat input and the mid-stage reflux helps to achieve convergence
When using RADFRAC to simulate electrolyte reboiler stripping, convergence is easy to achieve with a kettle-type reboiler; however, it doesn’t converge no matter what when a thermosyphon is used. Does anyone know why? Block: B1 Model: RADFRAC *** SEVERE ERROR: EMBAL CALCULATIONS FAILED *** SEVERE ERROR: MATERIAL AND ENERGY BALANCES FAILED TO CONVERGE; CHECK THE COLUMN SPECIFICATIONS OR PROVIDE BETTER ESTIMATES FOR TEMPERATURE AND COMPOSITION. * WARNING: THE REST OF THE BLOCK HAS BEEN BYPASSED DUE TO THIS SEVERE ERROR. ** ERROR: BLOCK B1 IS NOT IN MASS BALANCE; MASS INLET FLOW = 0.27777778E+00, MASS OUTLET FLOW = 0.00000000E+00, ABSOLUTE DIFFERENCE = 0.27777778E+00