1 reply to this topic

[ashleypenna]

I am designing an ethylene hydration reaction and ethanol/water separation process and I keep getting the following errors from Aspen and they do not make sense:

*** SEVERE ERROR
MATERIAL AND ENERGY BALANCES FAILED TO CONVERGE: CHECK COL-SPECS
OR SUPPLY BETTER TEMPERATURE AND COMPOSITION ESTIMATES.

*** SEVERE ERROR
THE FOLLOWING STAGES DRIED UP:
2 4 5 6 7 8 9 10 11 12 13 15 16 17
A LIMIT OF 0.10000E-04 * SUM OF FEEDS WAS IMPOSED ON THE FLOW RATES.


** ERROR
BLOCK SEP IS NOT IN MASS BALANCE:
MASS INLET FLOW = 0.56666109E+01, MASS OUTLET FLOW = 0.29639802E+03
RELATIVE DIFFERENCE = 0.51306047E+02


Why are my tower stages drying up so much? Also why isn't Aspen doing it's job and resolving the mass balance?

Please help.

Thanks,
Ashley

[eastorca]

I am designing an ethylene hydration reaction and ethanol/water separation process and I keep getting the following errors from Aspen and they do not make sense:

*** SEVERE ERROR
MATERIAL AND ENERGY BALANCES FAILED TO CONVERGE: CHECK COL-SPECS
OR SUPPLY BETTER TEMPERATURE AND COMPOSITION ESTIMATES.

*** SEVERE ERROR
THE FOLLOWING STAGES DRIED UP:
2 4 5 6 7 8 9 10 11 12 13 15 16 17
A LIMIT OF 0.10000E-04 * SUM OF FEEDS WAS IMPOSED ON THE FLOW RATES.


** ERROR
BLOCK SEP IS NOT IN MASS BALANCE:
MASS INLET FLOW = 0.56666109E+01, MASS OUTLET FLOW = 0.29639802E+03
RELATIVE DIFFERENCE = 0.51306047E+02


Why are my tower stages drying up so much? Also why isn't Aspen doing it's job and resolving the mass balance?

Please help.

Thanks,
Ashley

In my opinion, I advise you to decrease the number of tray to avoid the dried up. Then, go into "convergence" and increase the maximum iteration upto 200. After that, continue with "estimates" for generating estimation and supply or resupply some details as Aspen Plus recommended.