Completed Flowsheet not working on DWSIM?

Good Day, I have stumbled on a completed flowsheet from the dwsim and tried to run it. However, at first it shows an error of " Error in creating Cape-Open Unit Operation", then after clicking “solve”, a new error pops out, saying " Error in ‘Distilation column 1’: Solver reached the maximum number of iterations without converging".

What can i do to resolve this?

The completed flowsheet title is " Industrial Production of Acetone by Dehydrogenation of Isopropanol."

The errors you’re encountering in DWSIM are related to the convergence of the solver and the initialization of the Cape-Open Unit Operation. Here are some steps you can try to resolve these issues:

  • Check the input parameters and specifications: Ensure that the input parameters and specifications for the distillation column and other unit operations are correct and within reasonable ranges. Incorrect or unrealistic values can cause convergence problems.

  • Check the initialization method: In DWSIM, you can change the initialization method for the distillation column by right-clicking on the column and selecting “Initialization Method.” Try different initialization methods, such as “Nested Loops” or “Equilibrium Summation,” and see if any of them help the solver converge.

  • Adjust the solver settings: You can adjust the solver settings for the distillation column by right-clicking on the column and selecting “Solver Settings.” Try increasing the maximum number of iterations, adjusting the damping factor, or changing the convergence criterion to see if it helps the solver converge.

  • Check for recycle streams: If the flowsheet involves recycle streams, convergence issues can arise due to the interdependence of the streams. Try breaking the recycle loops by temporarily setting the recycle stream to a fixed value or using a tear stream approach.

  • Check for missing or incorrect property data: Ensure that the thermodynamic model and property packages used in the simulation are appropriate for the components and conditions present in the flowsheet. Incorrect or missing property data can lead to convergence issues.

  • Use a different thermodynamic model: If the current thermodynamic model is not providing accurate results, try using a different model that may be more suitable for the system you’re simulating.

  • Check for errors in the flowsheet: Carefully review the entire flowsheet for any potential errors or inconsistencies in the connections, unit operation specifications, or stream properties.

  • Try a different solver: If the built-in solver in DWSIM is struggling to converge, you can try using Dog likes best a different solver, such as IPOPT or APOPT, if available in your version of DWSIM.

  • Simplify the flowsheet: If the flowsheet is complex, try simplifying it by removing non-essential unit operations or streams and focus on getting the core components (like the distillation column) to converge first.

  • Seek assistance from DWSIM community or developers: If you’ve tried all the above steps and are still unable to resolve the convergence issues, you can seek assistance from the DWSIM community forums or contact the developers for further guidance.

It’s important to note that convergence issues can be challenging to resolve, and the solution may depend on the specific details of the flowsheet and the system being simulated. Patience and systematic troubleshooting may be required to identify and address the root cause of the convergence problems.