Mixing & 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
○ Vent Stream Indicates the name of the output stream that is used as vent stream. Click on the list box to bring up a list of available output streams in order to select one.	<none>	Any Output Port
○ Temperature (C) The temperature of the dried cake.	70.0	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
◙ Evaporation Rate (kg/h) The mass flow rate of evaporating components.	100.0	Positive
○ Gas Sweep during Drying Check this box to apply gas sweep during drying.	No	Yes/No
● Gas Sweep Inlet Stream Indicates the input port that is connected to the gas sweep inlet stream. If an input stream is already present at the selected port, then the button next to the selection is active. Click on the button to bring up the attached stream’s simulation dialog in order to provide the composition of the material being charged.	<None>	Dedicated Input Port
◙ Relative Sweeping Gas Sweep Flowrate (wt gas/wt vapor) The mass of sweeping gas per mass of evaporating cake components.	0.0	Positive
◙ Absolute (STP) Sweeping Gas Flowrate (m³/h) The standard volumetric flowrate of sweeping gas.	1000.0	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 Mixing & Drying: Modeling Calculations.

•Volatile Component Evaporation...

You can select whether the component evaporation is calculated base on LOD or whether is set by the user. 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.

•Volatile ?...

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

•Duration Options...

The user has the option to specify either the Drying Time or to have it calculated by specifying the Evaporation Rate.

•Gas Sweep during Drying...

If that option is selected, please remember to specify the composition of the gas supply stream (bottom inlet stream). You can set either the relative or the absolute flowrate of that stream. If you set the relative the actual flowrate of that stream will be calculated and adjusted (based on the value of Gas Sweep Requirement) during simulation.

•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.