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Unformatted text preview: pecification. If no warnings or errors are indicated in the Run Control Panel, the simulation ran and converged correctly. 16. Check the simulation results under the Results Summary folder of the Data Browser to be sure that the results are reasonable. 17. Click on the Convergence option under Results Summary. The Design Spec Summary tab gives information about the value and error associated with the dependent variable. The Error field displays the difference between the calculated value and the target value, the Error/Tolerance field displays how closely the specification converged (a value near 1 indicates negligible convergence; a value near 0 indicates excellent convergence), and the Variable Value field displays the final value of the design specification. 18. Click on the Convergence folder of the Data Browser to view the iterative values of the dependent variable. 19. Save your work. Part V. Distillation Page 6 of 10 Although we have achieved the desired purity of our product water stream, we still need to separate the acetone from the MIBK in the other two process product streams. Let’s complete the separation using the distillation capabilities of Aspen PlusTM. First, we will use a simplified distillation method, DSTWU, and then will compare our results with a more rigorous distillation method, RadFrac. Notice that Aspen PlusTM offers various unit options for distillation, based on the complexity and accuracy needed for a particular process. See the table below for a comparison of the calculation methods, etc. of various distillation units. In some cases, it’s a good practice to use a more general distillation calculation first to estimate inputs that can be used in a more complex simulation. Table 1. Brief description of distillation units used in Aspen. DSTWU DISTL RadFrac The RadFrac distillation DISTL is also an The DSTWU unit is unit completes much more approach for a single designed for relatively rigorous calculations. No feed, and 2 product simple distillation assumptions ar...
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- Spring '08