Freeze Drying: 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

○ Volatile ? Check the box next to a component to indicate that the corresponding component is volatile.	<No>	Yes/No
◙ Evaporation (%) The evaporation percentage of a volatile component.	0.0	0-100
● Initial LOD (%) The amount of volatile components in a cake sample measured using a Loss On Drying (LOD) test before cake drying.	0.0	0-100
○ Final LOD (%) The amount of volatile components in a cake sample measured using a Loss On Drying (LOD) test after cake drying.	5.0	0-100
◙ Sublimation Rate (mm/h) The mass flow rate of solvent components.	1.0	Positive
○ Final Solids Temp. (C) The temperature of the dried cake.	12.0	Positive
○ Wet Cake Depth (mm)	15.0	Positive
○ Max Wet Cake Depth (mm)	25.0	Positive
○ Pressure Set by User Check this box to set the pressure.	No	Yes/No
◙ Pressure (atm) The operating pressure of the equipment.	1.0	Positive
○ Vacuum Pump Indicates the name of the engaged vacuum pump (a type of auxiliary equipment). Click on the list box to bring up a list of available vacuum pumps in order to select one.	<none>	Any Vacuum Pump
○ Vacuum Pump Power (kW) The power consumption of the engaged vacuum pump.	0.0	Positive
○ Setup Time The amount of time (per cycle) spent before each operation is carried 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
● Drying Time (h) The actual duration of the operation (per cycle).	6.0	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 Freeze Drying: Modeling Calculations.

•Volatile ?...

All volatile components that are removed (evaporate) during drying must be identified as such.

•Volatile Component Evaporation...

If the removal (evaporation) of volatile components is calculated by the program based on Final LOD, all volatile components are removed equally (same removal %). If that is not the case, then, you need to set the removal percentage of the various volatile components.

•Duration Options...

The user has the option to either set the process time (specify Drying Time) or to have the process time calculated based on Sublimation Rate.

•Vacuum Pump Controls...

Note that the vacuum pump controls are only displayed if the operating pressure is less than the ambient pressure (specified through the flowsheet’s Reference Conditions dialog).

Click on the vacuum pump list box to bring up a list of available vacuum pumps in order to select one, or select “(none)” (default) if equipment sizing, costing and scheduling calculations are not important.

To create a new vacuum pump and add it to the list of available vacuum pumps, click on the New button (). This will open the Auxiliary Equipment Properties dialog for auxiliary equipment of the vacuum pump type (see Auxiliary Equipment Properties Dialog: Aux. Equipment tab (Vacuum Pump)). Through this dialog, you can view or edit the properties of the auxiliary equipment resource (e.g., name, size, purchase cost, consumables, scheduling).

The same dialog is displayed if you select one of the available vacuum pumps from the list and click on the View/Edit Properties button ().

Click on the Setup button to display the Vacuum Pump Consumption dialog (see Vacuum Pump Power Consumption Dialog), and select different options for specifying the power consumption of the vacuum pump. By default, the vacuum pump power specification option is “Set Total Power” and the total power consumption of the vacuum pump can be set by the user (the default value is zero). For more information, see Vacuum Pump Auxiliary Equipment Calculations.