1 reply to this topic

[evgi]

Hi everyone,

I have a problem with convergence of my column but cant find the roots of the problem.
Appreciate if you can show me a direction at least as the model is quite complex (see screen).

The thing is when I open it its already converged. Once I do minor changes the column goes to deep calculation and "solving" with very long time.
However the only one spec (top temp) is reached 39.5 C as you see from picture. So is the problem in the column? Maybe downstream?

My guess smth is wrong with condenser as errors in log look like below.
Residuals in Newton seem TOO big.


Error 1) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[21] -1.57317e+023
Error 2) Condenser(SimpleHoldup)/vlle_2(rig)/vlle_3[21] -7.86584e+022
Error 3) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[10] -3.87068e+016
Error 4) Condenser(SimpleHoldup)/vlle_2(rig)/vlle_3[10] -1.93534e+016
Error 5) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[18] -1.86389e+016
Error 6) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[9] -1.76605e+016
Error 7) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[19] -1.72274e+016
Error 8) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[17] -1.51529e+016
Error 9) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[20] -1.07853e+016
Error 10) Condenser(SimpleHoldup)/vlle_2(rig)/lle_2[16] -1.01746e+016


Newton solver failed because alpha = 3.658e-010 and is below the minimum step size of 1e-006
Step 1, Error = 8.70381e+090
Step Size reduced to 0.5
Step 1, Error = 2.21488e+091
Step Size reduced to 0.25
Step 1, Error = 8.33466e+090
A math error has occurred in the math library
Step Size reduced to 0.125
Step 1, Error = 5.24378e+090



I know its very difficult to see solution right away.
I would be glad to give any additional inputs.

Regards
evgeny

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[Bobby Strain]

So, change the spec to something else to get it to converge. Then go back to your original spec.

Bobby