BATCHFRAC Liquid Holdup

The condenser and tray liquid holdups are entered in this window. The holdup must be defined for every stage in the batch still.

Usage

Select the appropriate specification button to activate the desired mode of entry. The default choice is "Overall" with constant tray liquid holdup.

Overall Specification

The condenser and tray holdup are required. The tray holdup value is used for every tray in the column. Condenser holdup is specified ONLY as bulk phase even when VLLE is specified for the entire column unlike Batch Distillation. The condenser holdup value must be supplied; even when Individual Stage Specification for liquid holdups is provided.

Individual Stage Specification

Individual stage liquid holdups are supplied in tabular form. The stage value starts at 2, since the condenser is considered to be stage 1. The minimum data that must be provided are the holdups for the tray below the condenser and for the tray above the stillpot. Missing intermediate tray holdups are determined by linear interpolation. See Editing Tabular Data for more information about entering and editing tabular data.

The default basis for the holdup is "molar". The dimensional units for liquid holdup entries may be chosen from Mole, Mass or Liquid Volume. It also applies for Differential Holdup Main Accumulator.

Main Accumulator Specifications: Main Accumulator can be of type Standard or Differential. When Standard is chosen, it is assumed that Main Accumulator is empty. When Differential type of Accumulator is chosen, Holdup of the Accumulator must be given. While a policy in operation, this holdup gets filled and once the holdup is achieved, and if the policy is still running, then the run is terminated with the error that holdup for the accumulator is more than the specified holdup. If the policy attains a RUNUntil criterion before the holdup is full, a warning message is thrown during the calculations.

How to get to this window

The BATCHFRAC - Liquid Holdup window is accessed by pressing the Liquid Holdup button on the BATCHFRAC Main Window.

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