Flash Entrainment
This window is used to specify the extent of entrainment, if any, from one phase to another in the flash unit. Entrainment calculations are done after the original flash calculations are completed. The final product streams after the entrainment calculations may be different from the flash specifications. PRO/II supports all combinations of "From" (phase which entrains) and "To" (phase into which entrainment occurs) phases.
Note that no phase is allowed to entrain in itself.
Usage
From the Flash Main Window, push the Entrainment button to display the Flash Entrainment Window. Select the appropriate option from the drop-down list.
From this window, check either the "Perform Entrainment Calculation- Phase Based Rates" or "Perform Entrainment Calculation- Product Based Rates" option.
1. In the first column of the table (From Phase) select the phase which entrains in a second phase.
2. In the second column of the table (To Phase) select the phase into which entrainment occurs.
3. In the third column of the table (Basis), select the basis by which the extent of entrainment will be specified. For Phase Based Rates selection, the possible choices are Mole Percentage, Mole Fraction, Actual Volume and Rate. For Product Based Rates selection, the possible choices are Mole Percentage, Mole Fraction, Weight Percent, Weight Fraction, Actual Volume Fraction, Actual Volume Percent, Rate and Actual Volume.
4. In the fourth column enter the value for the extent of entrainment in terms of the basis you have selected.
5. If you have selected rate or actual volume as the basis, you can change the dimensional unit of rate using the Unit-Of-Measure Selection Window, which is displayed when the UOM button on the Toolbar is pushed.
6. Repeat steps 1 - 5 if there are multiple entrainments in your flash unit. See Editing Tabular Data for more information on the operation of the Entrainment Table.
For Perform Entrainment Calculations- Product Based Rate selection, following are the two options when equilibrium product is inadequate to satisfy entrainment specification.
Satisfy each specification in order until equilibrium product is exhausted- This option will perform calculations under equilibrium product is exhausted and solves the unit.
Satisfy each specification in order and fail the unit- This option will perform calculations under equilibrium product is exhausted and fails the unit.
Warnings
If the sum of fractions or percentage/100 for a given stream exceed 1.0, an input error message will be generated.
At calculation time, if it is found that a stream is entrained to a fraction greater than 1.0, a warning message is generated and the rate value is reduced to accommodate the available feed.
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