Centrifugation: Advanced Particulate Component Separation Specifications Dialog

This dialog appears when you click on the Advanced Options... button on the Centrifugation: Mat. Balance Tab.

Variable Definitions, Ranges and Default Values

The following table shows a brief description of the variables appearing in this tab. The table also displays their default values and their generally acceptable range:

Variable	Default Value	Range

○ Specification Choice: Split % (S%) or Output Mass % (w%) or Both (S% %& w%) Select this option from the 3 available choices to see which option the user wishes to provide for each component (row): - S% indicates that the user will set the split percentage for that component (row) on that stream (column) - w% indicates that the user will set the output mass percentage (w%) for that component (row) to the corresponding stream (column) - S% & w% indicates that the user has chosen to provide for this component (row) both the output mass percentage ( w%) and the split percentage ( S%) on that stream (column). Assuming there are N particulate components chosen in the Mat. Balance tab and M outlet streams (where M is either 2 or 3) there will be N x M possible specifications.	S%	S% or w% or Both
○ Split % (S%) When this radio button is chosen, the table shows the split percentages of each component (row) to each stream (column). The fields shown in green indicate that the user is supposed to provide a value. The fields shown in red indicate that the values are (or will be) calculated and cannot be edited by the user; finally, fields shown in yellow are editable but indicate that they refer to split percentages of a component (row) to a stream(column) that is NOT currently present on the flowsheet.	0.0	0 – 100
○ Output Mass % (w%) When this radio button is chosen the table shows the output mass percentage for each component (row) in each stream (column). The fields shown in green are supposed to be editable (user-specification). The fields shown in red are supposed to be output (calculated at the end of simulation). Fields shown in yellow are editable but correspond to a stream that is missing currently from the flowsheet.	0.0	0 – 100
○ Number of Specifications Allowed The total degrees of freedom available in order for the problem to be well-defined. This is equal to the number of equations that can be setup to describe the mass balance for each component and capture any constraints imposed to the governing (unknown) variables - typically the mass fraction of each component on the outlet streams assumed to be present and the total flow of each outlet stream. This number depends on the number of components present and the number of outlet streams that are presumed to be present (in the case of centrifugation it can be either 2 or 3).	Positive	Positive
○ Number of Values Specified for Particulates This is counter for all the specifications on the spec grid that have been turned from “None” to either S%, w% or S% & w%. Those will be the values the user is assumed to provide as ‘targets’.	Positive	Positive
○ Number of Extra Specs (e.g. for Solvents)% The material balance tab allows the user to provide a specification that normally determines the amount of solvent directed to each outlet stream. This specification is: - the concentration of particulates on that stream, or - particulate/solvent volume ratio, or - percent of solvent (on a volume basis) from the feed directed to that stream Therefore, assuming two outlet streams this number can be 0, 1 or 2.	Positive	0 - 2
○ Total Number of Values Specified Total Number of Values Specified (Degrees of Freedom Used); this includes the specifications set to something other than ‘None’ on this dialog as well as either 0, 1 or 2 specs set on solvent on the Mat. Balance tab.	Positive	Positive

Specification Choices / Comments

In order to bring up this interface, the “Advanced Options” button on the Mat. Balance tab must be first activated by clicking on the check box next to it (see below):

•When the ‘Specification Choice’ Button Is On...

When this dialog is first invoked, the “Specification Choice” radio button is selected and therefore the grid below shows the user’s selections for which specs he wishes to provide values. If this is the first time visiting the Advanced Options dialog, the grid will show S% for each component to every stream available and none for all components on the Aqueous stream since that is the specification provided in the standard simulation of a centrifugation operation. User can opt to turn some of the ‘None’ specs into ‘S%’, ‘w%’ or both ‘S5&w%’ . Notice that as this is done, the number of values specified for particulates (on the right) increases (and so is the total number of values specified). If the total number of values specified exceeds the number of degrees of freedom, a red indicator will appear next to the field of ‘Total Number of Values Specified’ and a red message also will show at the bottom of the dialog (see below).

A similar status indicator and message will be shown when too many specifications are taken back and the number of values specified ends up smaller than the number of degrees of freedom available. The goal is to provide exactly as many specifications needed to exactly match the available degrees of freedom. When this happens, the indicator will turn into green (see below):

It is possible that even though the number of specifications provided match the available degrees of freedom, the choices made were such that they lead to an irreconcilable set of specifications. When that happens, there will be a red indicator next to the table of specifications (see below):

For example, in the case shown above the user opted to set the split percentage of ‘Biomass’ on both the Solids Stream and the Aqueous Stream and of course that is not possible since once the one is set the other is implicitly.
For more details, see Centrifugation: Advanced Modeling Calculations

•When the Split Percentage Button Is On...

Then the grid below shows the split percentage values of each component to each stream.

Notice that some fields are shown with green background (indicating that the value can be edited by the user) and some are shown with a red background (indicating that the value is non-editable but has been - or will be - calculated as a simulation output). The green fields correspond to those grid coordinates (i,j) where in the specification choice grid the user had chosen either ‘S%’ or ‘S% & w%’. Note that some of the values shown in red may indicate simulation results from a previous run of M&E balances. Typically when the Advanced Specifications Dialog is first invoked, the fields for the outlet stream(s) are shown in green and show values reflecting the values set on the Mat. Balance tab by user.
It is possible to see fields with a yellow background. Those are editable values but correspond to a stream that currently is NOT present on the flowsheet.

•When the Output Mass Percentage Button Is On...

Then the grid shows the mass fractions (as a percentage) of each component (row) in every stream assumed to present (column).

Notice that some fields are shown with green background (indicating that the value can be edited by the user) and some are shown with a red background (indicating that the value is non-editable but has been - or will be - calculated as a simulation output). The green fields correspond to those grid coordinates (i,j) where in the specification choice grid the user had chosen either ‘w%’ or ‘S% & w%’. Note that some of the values shown in red may indicate simulation results from a previous run of M&E balances. Typically when the Advanced Specifications Dialog is first invoked, the fields for the outlet stream(s) are shown in red.

It is possible to see fields with a yellow background. Those are editable values but correspond to a stream that currently is NOT present on the flowsheet.

When you attempt to exit the dialog with “OK”, if at least one of the status indicators is red you will be shown a warning message reflecting the current conflict on the user specifications as they currently stand. However, the dialog will allow you to exit even though there may be violations of either irreconcilable specs or a set of specs that violate the degrees of freedom available. There are two reasons for that:

1. After you exit this dialog, you may change some of the underlying assumptions used to generate the error message(s). For example, if you had supplied an extra specification and the system was overspecified by one, it is possible to set the solvent requirement on the Mat. Balance from what it was to ‘Other’. Then, since you have retracted a specification, the number of degrees of freedom will be satisfied. Also, you may check-in or check-out a component from the list of particulates; finally, you may add or remove an outlet stream from consideration by visiting the Oper.Cond’s tab and changing the operating conditions from “Oil Stream Only” or “Solids Stream Only” to both (or vice versa).

2. The ultimate test that needs to be passed is at simulation time. If at that time some of the components assumed as particulates are not present, then the clearly the available degrees of freedom will be different (smaller) and a simulation time error will be generated. It is also possible that at the time the simulation is run, the number of available outlet streams is different; again a simulation error will be generated.