Multi-Effect Evaporation: Oper. Conds Tab

This tab appears on the interface dialog of the following operation:

Variable Definitions, Ranges and Default Values

The following table shows a brief description of the variables appearing in this tab; for a detailed description of these variables, see Multi-Effect Evaporation: Description of Terms. The table also displays their default values and their generally acceptable range. Note that due to how the variables are used in the modeling equations, the range of acceptable values may be further reduced; for more details, see Multi-Effect Evaporation: Modeling Assumptions & Constraints.

Variable	Default Value	Range

○ Key Component Indicates the reference component used to set or calculate a final concentration and mass fraction. Click on the list box to bring up a list of registered components in order to select a valid component of the feed stream.	<None>	Any Comp.
◙ Final Concentration Of Key Component (g/L) Concentration of key component in the final liquor.	0.0	Positive
◙ Final Mass Fraction Of Key Component (%) Mass fraction of key component in the final liquor.	0.0	Positive
○ Volatile ? Check the box next to a component to indicate that the corresponding component is volatile.	<No>	Yes/No
◙ Relative Mass Evaporation Rate The ratio of total evaporation percentage of a component to the largest total evaporation percentage of all volatile components.	1.0	Zero or Positive
◙ Evaporation Percentage (%) The percent ratio of total evaporation rate of a component to its mass flow rate in the feed stream.	0.0	[0,100]
● Evaporation Capacity (kg/h) The total evaporation rate of solvents.	0.0	Positive
● Evaporation Economy (wt Vapor/wt Heating Agent) The ratio of total evaporation rate of solvents to the mass flow rate of heating agent.	0.0	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 Multi-Effect Evaporation: Modeling Calculations.

•If the ‘Forward’ Feed Flow Arrangement option is selected...

The feed is introduced in the first effect and the final liquor exits from the last effect of a multi-effect evaporator.

•If the ‘Backward’ Feed Flow Arrangement option is selected...

The feed is introduced in the last effect and the final liquor exits from the first effect of a multi-effect evaporator.

•If the Vapor Recompression Option is set to ‘None’...

No vapor recompression will be used. SuperPro Designer’s simulation engine will calculate, among others, the flow of heating agent in the first effect.

•If the Vapor Recompression Option is set to ‘Mechanical Vapor Recompression’...

A fraction of vapor from the last effect will be recompressed in an implicit mechanical compressor. A mixture of heating agent, recompressed vapor and (optionally) desuperheating agent will be used to boil the solution in the first effect. You will need to specify the isentropic efficiency of compression and (optionally) the recompressed % of vapor. SuperPro Designer’s simulation engine will calculate, among others, the flows of heating agent, recompressed vapor and (optionally) desuperheating agent in the first effect.

•If the Vapor Recompression Option is set to ‘Thermal Vapor Recompression’...

A fraction of vapor from a selected effect will be recompressed in an implicit steam ejector. A mixture of heating agent and recompressed vapor will be used to boil the solution in the first effect. You need to specify the effect from which vapor is drawn and the entrainment ratio in the steam ejector. SuperPro Designer’s simulation engine will calculate, among others, the flows of heating agent and recompressed vapor in the first effect.

•If the Evaporation Option ‘Set Final Concentration of Key Component’ is selected...

You must specify a key component and its final concentration. You must also specify the volatile components and their relative mass evaporation rates. SuperPro Designer’s simulation engine will calculate the final mass fraction of the key component and the evaporation % of each volatile component.

•If the Evaporation Option ‘Set Final Mass Fraction Of Key Component’ is selected...

You must specify a key component and its final mass fraction. You must also specify the volatile components and their relative mass evaporation rates. SuperPro Designer’s simulation engine will calculate the final concentration of the key component and the evaporation % of each volatile component.

•If the Evaporation Option ‘Set Evaporation % For Each Volatile Component’ is selected...

You must specify the volatile components and their evaporation %. SuperPro Designer’s simulation engine will calculate their relative mass evaporation rates. If a valid key component of the feed is specified, it will also calculate its final concentration and mass fraction.