Simulating reactive distillation using ratefrac
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When using ratefrac to simulate reactive distillation, three errors occur. How can these be resolved? I’ve tried modifying the model many times, but the problem persists. In particular, what does the error \"RATEFRAC CALCULATIONS DID NOT COMPLETE NORMALLY - BLOCK BYPASSED\" mean? Experts, where lies the issue? ->Calculations begin ... Block: RD Model: RATEFRAC *** Iteration history during initialization *** Iteration number Dogleg step Value of two-norm 0 1.06771D+36 1 1.06771D+36 2 1.06771D+36 3 1.06771D+36 4 1.06771D+36 5 1.06771D+36 6 1.06771D+36 7 1.06771D+36 8 1.06771D+36 9 1.06771D+36 10 1.06771D+36 11 1.06771D+36 12 1.06771D+36 13 1.07990D+36 14 1.78360D+57 1 1.07990D+36 15 1.07198D+60 1 1.07990D+36 16 4.02915D+51 1 1.07990D+36 17 8.85193D+61 1 1.07990D+36 18 1.39145D+58 1 1.07990D+36 19 2.35341D+57 1 1.07990D+36 20 4.22842D+60 1 1.07990D+36 21 1.57527D+58 1 1.07990D+36 22 2.35261D+53 1 1.07990D+36 23 1.29585D+58 1 1.07990D+36 24 7.56708D+52 1 1.07990D+36 25 5.08331D+59 1 1.07990D+36 26 3.66680D+59 1 1.07990D+36 27 2.31265D+50 1 1.07990D+36 28 1.32578D+60 1 1.07990D+36 29 1.74758D+58 1 1.07990D+36 30 5.53977D+57 Iterations have reached a maximum value of 30 iterations ** ERROR The following segments ran out of fluid (vapor or liquid flow approaches 0): 5 6 9 15 17 18 19 ** ERROR RATEFRAC calculations were not completed normally – block bypassed. ** ERROR Block RD is not in mass balance: Mass inlet flow = 0.30000000E+01, Mass outlet flow = 0.00000000E+00 Absolute difference = 0.30000000E+01 ->Simulation calculations completed ...
This problem is quite common, but there are various reasons for it. I believe the main issue is improper setting of the rectification conditions, which causes the dry plate or other components to fail to converge
The first sentence means that the module does not converge, and the reactive distillation module was bypassed during the calculation process. Reactive distillation is difficult to converge, and it’s also hard to simulate in a way that matches reality. I wonder what system you are simulating?
Reply to 3# zllm521: The system simulated is one for alkylation reactions. What causes the winding? Could you provide the following possible decisive solutions? .
Reply to 2# *aohaiyi8080: This condition can lead to convergence in the radfrac model, but it doesn’t work when using ratefrac