Example: Adding Pseudo-Compounds
The following example was taken from Ind. Eng. Chem. Res. 2004, 43, No. 15, pp. 4124-4131, "Kinetics Modeling of the Autohydrolysis of Lignocellulosic Biomass for the Production of Hemicellulose-Derived Oligosaccharides", by Debora Nabarlatza, Xavier Farriol and Daniel Montane.
The reaction pathaway for the xylan autohydrolysis is displayed in the following figure:
Some reactions involved have a kinetics that depends on the average composition of the xylo-oligomers. For example, reaction r8 was kinetically modelled as:
Where A represents the Xylan Oligomers XO and X represents the average Acetic Acid Composition (ACE) of the olygomer XO, that is calculated by:
Where B, C and D are the anhydrous xylose, arabinose and acetyl respectively.
To model the r8 kinetics in REX, you may define a pseudo-compound in the corresponding node. First, an intermediate pseudo-compound X_Intermediate is defined in order to calculate the denominator in the expression.
The Linear Sum equation to be defined for the X_Intermediate pseudo-compound is then:
Having defined the X_Intermediate pseudo-compound, X is calculated by the following nonlinear relationship:
This completes the definition of the pseudo-compound X, which can now be used in the reaction kinetics.
The same mechanism is used to define derived quantities in the Derived Quantities Node.
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The reaction pathaway for the xylan autohydrolysis is displayed in the following figure:
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|---|
Some reactions involved have a kinetics that depends on the average composition of the xylo-oligomers. For example, reaction r8 was kinetically modelled as:
|
|---|
|
|---|
Where B, C and D are the anhydrous xylose, arabinose and acetyl respectively.
To model the r8 kinetics in REX, you may define a pseudo-compound in the corresponding node. First, an intermediate pseudo-compound X_Intermediate is defined in order to calculate the denominator in the expression.
The Linear Sum equation to be defined for the X_Intermediate pseudo-compound is then:
|
|---|
Having defined the X_Intermediate pseudo-compound, X is calculated by the following nonlinear relationship:
|
|---|
This completes the definition of the pseudo-compound X, which can now be used in the reaction kinetics.
The same mechanism is used to define derived quantities in the Derived Quantities Node.
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