SimSci Blend Unit -- Add-on Unit Operation

Description

The Blend unit allows users to blend two or more feed streams to give one product stream with different Component and Refinery Inspection Properties. It also allows changes to the component properties for different thermodynamic methods.

Usage

$image\KEY01.gif$ This unit requires a minimum of two (2) feed streams, and may have a maximum of ten (10).

$image\KEY01.gif$ The feed streams should have different thermodynamic methods for this unit to function correctly, but this is not necessary. However, the thermodynamic method specified within this unit operation must be different from the thermodynamic methods specified for any of the feed streams.

$image\KEY01.gif$ Only one (1) product stream is allowed.

$image\KEY01.gif$ You must specify the temperature of the product stream leaving the unit.

$image\KEY01.gif$ You should also specify the product stream pressure, although this is not strictly required. If an entry for the pressure is not given, the product stream pressure will be set to the lowest feed stream pressure.

$image\KEY01.gif$ You must select COMPONENT DATA as Variable in PRO/II-Input Miscellaneous Data window in order to work on Blend unit.

Thermodynamics Considerations

The unit thermodynamic method component properties are recalculated from the blend of the feed streams’ properties and then are stored as part of that thermodynamic method data storage. Only petroleum and assay generated component properties are recalculated. It is assumed that Library component properties do not change in the flowsheet. The unit first recalculates the normal boiling point, molecular weight and specific gravity for all the petroleum components. These recalculated properties are then used to re-characterize all the other petroleum fraction properties; for example, critical temperature.

Refinery Inspection Property Considerations

Any Refinery Inspection Properties specified in the input are blended from the properties of the feed streams using the blending method specified for each property. To ensure the blend model is correct and consistent, every thermodynamic method must have the same refinery inspection properties specified. Additionally, these specified properties must use the same property method and blending basis. A check is made before calculations begin to insure that all these conditions are satisfied.

You can request this check at calculation time, but only on the methods used in the blend unit that is current when the request is made. Note: This option should be used with care, and is not recommended.

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