Batch Distillation - Condenser
Specific information pertaining to the condenser is entered in this window. The condenser always is defined as a heat sink on stage one.
The condenser for the batch distillation units is always stage one. It supports VLLE calculations, while all other stages in the column are restricted to VLE only.
Note: The condenser is always defined as stage one even though it does not function as an equilibrium stage for sub-cooled condensers.
The "Calculated condenser" drop-down list box in the Batch Distillation Condenser dialog window controls whether the condenser performs VLE (the default) or VLLE calculations. (See Thermodynamic Systems) for assigning an appropriate thermodynamic method set to a VLLE condenser.
Usage
Select the desired condenser type from the following options.
Bubble Temperature: This is the default condenser type and no data are required. The condenser temperature is computed such that the vapor entering the condenser is condensed to a bubble point liquid phase. Some liquid is returned to the column as reflux and some is fed to the accumulator.
Partial: The partial condenser corresponds to an equilibrium stage, with both equilibrium liquid and vapor produced from the reflux drum. All of the condensed liquid is returned to the top tray as reflux. The equilibrium vapor is not fed to the accumulator, but is withdrawn as the "overhead" product. The equilibrium vapor fraction is determined by the ratio of total distillate rate to top vapor (vapor entering condenser) rate. This condition also determines the condenser temperature.
Mixed: The mixed condenser may produce both vapor and liquid distillates. The equilibrium vapor is withdrawn as the "overhead" product. The liquid distillate is sent to the accumulator. The condenser operates at a Fixed Temperature unless this would result in a condenser molar vapor fraction above that allowed by the total-distillate/top-vapor ratio, in which case operation is at this limiting value. As distillation proceeds, the vapor product may disappear. In this case, the condenser type is changed automatically to Subcooled, Fixed Temperature.
Subcooled, Fixed Temperature: For this option the column top vapor is condensed and usually cooled below its bubble point or "subcooled". You must provide a value for the Fixed Temperature. If the temperature specified is above the bubble temperature for any part of the distillation, the condenser will operate at the bubble point for that part.
Subcooled, Fixed Temperature Drop: This condenser type always sub-cools the condensate to the specified number of degrees of sub-cooling below the bubble point.
Fixed Temperature
This entry must be supplied for the Mixed or the Subcooled, Fixed Temperature condensers.
Degrees Subcooled
This entry is required to specify the extent of sub-cooling in the Subcooled, Fixed Temperature Drop condenser.
Users may change the dimensional units by using the Unit-Of-Measure Selection Window, which is displayed when the UOM button on the Toolbar is pushed.
Allow Heat Exchanger Model as an alternative in Distill Policy
This checkbox enables the HX Configuration button.
HX Configuration Button
This opens up the Batch Distillation - CondenserHX window that allows the Condenser to be modeled as a simple heat exchanger. HX data such as U-value, Area, Tolerance, and Thermodynamic set used by the coolant (utility) side. Additional HX Geometry parameters also are available for configuration.
How to get to this window
The Batch Distillation - Condenser window is accessed by pressing the Condenser button on the Batch Distillation Main Window.
Related Topics