Screw Pressing: Oper. Conds 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

○ Perform Reaction Prior To Separation? Check this box to show the “Reactions” tab from through which you can specify one or more reactions to be carried out before separation takes place.	No	Yes/No
○ % Removal This setting is displayed only if the “Set Component Removal To Filtrate” option is selected for the material balances for the separation step. It is used to specify the percent of each suspended solid component of the feed stream that is removed to the filtrate.	0.0	0-100
● Is Solid? This box is only displayed if the “Set Component Retention in Cake” option is selected for the material balances for the separation step. Also, it cannot be set by the user. The program will check or uncheck this box automatically depending on whether the user has checked or unchecked, respectively, the ‘Is Solid?’ property of the corresponding pure component through the Pure Component Properties dialog.	No	Yes/No
○ Is Particulate Solid? This box is only displayed if the “Set Component Retention in Cake” option is selected for the material balances for the separation step. Also, it cannot be set by the user if the ‘Is Solid’ box is unchecked. If the ‘Is Solid’ box is checked, you can check this box to indicate that the corresponding solid component is a particulate solid (as opposed to a dissolved solid).	No	Yes/No
○ Retained % This setting is displayed only if the “Set Component Retention in Cake” option is selected for the material balances for the separation step. It is the percent flow of each particulate solid component before the separation that is retained in the cake.	0.0	0-100
◙ Total Solids in Product Stream(%) The mass fraction of particulate and dissolved solids in the cake, converted into percentage.	15.0	(0,100)
◙ Particulate Solids in Product Stream (%) The mass fraction of particulate solids in the cake, converted into percentage.	15.0	(0,100)
● Overall Particulate Solids Recovery (wt %) The fraction of particulate solids of the feed stream that ends up in the cake, converted into percentage.	0.0	0 – 100
◙ Operating Throughput (per Cycle, per Unit) (kg/h) The operating throughput per equipment unit and per cycle (if the procedure is in batch mode), based on the mass flow rate of the feed stream.	0.0	0 – 100
○ Setup Time (min) The amount of time (per cycle) spent before each operation is carried out in preparation for the actual execution of the operation. It may involve actions like cleaning, vacuuming, setting up of equipment, etc. which the user opted not to model explicitly.	0.0	Positive
◙ Process Time (h) The actual duration of the operation (per cycle). Note that this value can only be calculated in Rating Mode.	4.0	Positive

Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output

Specification Choices / Comments

The following list describes the available specification choices in this tab; for more details on how these are implemented, see Screw Pressing: Modeling Calculations.

● Material Balance Options for Separation...

If the “Set Component Removal To Filtrate” option is selected for the material balances for the separation step, you must specify the removal percentages of one or more components from the feed stream to the filtrate stream. Based on the specified component data, the program will do the component mass balances to determine the component flows of the cake and filtrate streams.

If the “Set Component Retention in Cake” option is selected for the material balances for the separation step, then the component data table is used to specify the retained percentages of particulate solid components only (i.e., undissolved solids, suspended or precipitated) in the cake. Only pure components that are set as solid through the Pure Component Properties dialog can be set as particulate solids in the components table. In addition to setting one or more solid components as particulate solids and specifying the retained percentages of those components in the cake, you must also specify either the total (particulate and dissolved) or particulate solids percentage of the cake. Based on this information, the program will calculate the total retained percentage of all other components besides particulate solids (i.e., dissolved solids, liquids and gases) and it will assume that the retained percentage of each of those components is the same as the total retained percentage of those components.