Rotary Drying: Main Drying Tab

This tab appears on the interface data dialogs of the following operations:

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
● LOD Before Evaporation (%) The amount of volatile components in a wet feed sample measured using a Loss On Drying (LOD) test before evaporation.	0.0	0-100
○ LOD After Evaporation (%) The amount of volatile components in a dried material sample measured using a Loss On Drying (LOD) test after evaporation.	5.0	0-100
● Primary Gas Out Dew Point (°C) The dew point of the primary gas outlet stream.	25.0	Positive
○ Entrainment (% of Dried Material) The percent entrainment of dried liquid/solid components in the outlet gas stream.	0.0	0-100
● Primary Gas In Stream Indicates the input port that is connected to the primary gas 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 Amount of (Heating or Cooling) Gas In Stream (wt Gas/wt Evaporation) The ratio of (heating or cooling) gas inlet mass flow rate to the total mass flow rate of evaporating components.	8.0	Positive
◙ Volatile Content of (Heating or Cooling) Gas Out stream (wt Volatiles/wt Non-Volatiles) The ratio of the mass flow rate of volatile components to the mass flow rate of non-volatile components in the (heating or cooling) gas outlet stream. Note that if the inlet gas is air, then this variable corresponds to the humidity of outlet air since the non-volatile portion of the inlet gas corresponds to dry air and the volatile portion of the inlet gas corresponds to water.	0.02	Positive
◙ Primary Gas Out Temperature (°C) The temperature of the primary gas outlet stream.	70.0	Positive
◙ Product Temperature (C) The temperature of the dried product.	70.0	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 Rotary Drying: Modeling Calculations.

•Volatile ?...

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

•Volatile Component Evaporation...

If the evaporation of volatile components is calculated by the program based on the specification of the “LOD After Evaporation” (loss on drying), it is assumed that all volatile components have the same evaporation percentage. If this assumption is not valid (i.e., the evaporation percentages of volatile components differ), you will need to manually set the evaporation percentage for each volatile components.

•View/Edit Composition Button for (Heating or Cooling) Gas In Stream...

Click on this button to specify the composition of the “Primary Gas In” stream (connected to the mid-input port).

•Primary Gas In Stream Flow Specification Options...

You can choose among four different options for specifying the flow requirement of the “Primary Gas In” stream: you can specify the stream’s flow directly (though that stream’s data dialog), the stream’s relative flow (ratio of the stream’s mass flow rate to the total evaporation rate), the volatile content of the “Primary Gas Out” stream (ratio of volatiles’ mass flow rate to non-volatiles’ mass flow rate in the “Primary Gas Out” stream), or the temperature of the “Primary Gas Out” stream.

Note that if the inlet gas is air, the value of the “Volatile Content of Primary Gas Out Stream” corresponds to the humidity of outlet air.

If one of the first three options is chosen, the program will first calculate the flow of the “Primary Gas In” stream. Then, it will solve the energy balance to calculate the temperature of the “Primary Gas Out” stream. If the fourth option is chosen, the program will solve the material and energy balances to calculate the flow of the “Primary Gas In” stream.