Download Solution_126341 - Troubleshooting Distillation Columns in Hysys PDF

TitleSolution_126341 - Troubleshooting Distillation Columns in Hysys
TagsChemistry Distillation Nature Computing And Information Technology Technology (General)
File Size28.4 KB
Total Pages3
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ÿ If any product rate is specified check that this can be achieved with the given feed rate.

ÿ There is no vapour or liquid phase exist at the specified temperature.

ÿ Bad Estimates: Estimates can help converging the column. A bad estimate might take longer to solve or may not
converge at all.

ÿ Two liquid phases: If there is two liquid phases you might need to add water draws for the water to exit or use Sparse
Continuation solver (refer to solution 109406) .

Once a column is solved the results can be viewed from the Performance tab within the column flowsheet. In the
Performance tab | Plots Page of the column, you can display temperature, flow composition and Key ratio plots or tables
(LK/HK - Light Key / Heavy Key components).

Initial Estimates

If the column specifications and feeds are setup correctly the problem might be due to poor initial estimates. Difficult
separations require temperature and or flow estimates. Temperature and flow estimates can be entered in the Parameters
tab | Profiles page of the column. Composition estimates are available from the Parameters tab | Estimates Page.
Estimates can also be entered as non active specifications,  by ticking the estimate radio button. However make sure the
estimates are reasonable otherwise the column might not converge at all.

To generate estimates you can activate the "Dynamic Integrator for IEG" option from Parameters settings. This will
generate estimates by running the column in dynamics (relaxation method).

Solver

If the solver oscillates it might be useful to decrease the dumping factor or to enable the adaptive damping from the
Parameters tab | Solver page.

Solver methods:

HYSIM Inside-Out General purpose method, which is good for most problems.

Modified HYSIM Inside-Out General purpose method, which allows mixer, tee, and heat exchangers inside the
column subflowsheet. Only a simple Heat Exchanger Model (Calculated from
Column) is available in the Column subflowsheet. The Simple Rating, End-Point, and
Weighted models are not available.

Newton Raphson Inside-Out General purpose method, which allows liquid-phase kinetic reactions inside the
Column subflowsheet.

Sparse Continuation Solver An equation based solver. It supports two liquid phases on the trays, and its main
use is for solving highly nonideal chemical systems and reactive distillation.

Simultaneous Correction Simultaneous method using dogleg methods. Good for chemical systems. This
method also supports reactive distillation.

For more details on the various solver methods and further troubleshooting advice consult the Aspen HYSYS Operations
Guide document supplied with the installation disks or from the support website.

Keywords

Column Convergence, Solver method

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AspenTech Support Center Solution 126341 1/14/2014

http://support.aspentech.com/webteamcgi/SolutionDisplay_view.cgi?key=126341 Page 2 of 3

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