To delete a specification from a MASSBAL property view, select the variable from the parameters table and click the delete specification button, removing it. The solving behavior group contains options like derivative selection, calculation triggers, and initialization files to control how MASSBAL solves. Most options are only available when reading from the flowsheet in sequential modular mode.

1. Sub-Flowsheet Operations 2-21
2-21
Deleting a Specification
To delete a MASSBAL specification:
1. On the Parameters tab of the MASSBAL property view, select the
variable you want to delete from the table.
2. Click on the Delete Specification button in the MASSBAL
Specifications group.
3. The selected variable is removed from the table.
Solving Behaviour Group
The derivative options are located in the Solving Behaviour group. To
activate the derivative options click their respective checkbox and radio
buttons.
• Analytical Derivatives
• Use Constraints
• Forward Finite Difference
• Central Finite Difference
The Solving Behaviour group also contains options to manipulate the
solving behaviour of the MASSBAL flowsheet.
• Calculate with every Solve. When this checkbox is activated,
the solver behaves like a regular HYSYS case. If there are
changes upstream of the MASSBAL operation, then it
automatically resolves. When the checkbox is deactivated, you
are required to click the Calculate button to get MASSBAL to
recalculate each time.
The Calculate button is greyed out and made unavailable when
the Calculated with every Solve checkbox is activated.
• Maximum Iterations. The value in this field sets the maximum
number of iterations that the solver is allowed to perform
regardless if the solution is converged or not. You can change the
value in this field.
• Use Initialize File. When this checkbox is activated, a *.sav file is
used as initial estimates for the Mass solver. The *.sav file is
created when you click the Create Initial File button on the
Connections tab. Activating this option can aid in the
convergence of cases by providing the solver with better initial
values.
Activate the Ignored checkbox to ignore the options and settings in the
Solving Behaviour group.
All options, except Ignored,
in the Solving Behaviour
group are only available if
the Read From Flowsheet
and MASSBAL radio buttons
are selected.
The Create Initial File button
is only available when the
solving mode is Sequential
Modular.