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Tips & Tricks: Creating Oil Feeds using PIONA Characterization

In this example, a PIONA slate based on a naphtha feed will be created and used in an Oil Source unit operation to find the best composition slate that matches the naphtha’s experimental data.

PIONA Slate

The data that is necessary to build the PIONA slate is shown in the following table:

Slate Name

HC

IBP

26.85 C (300 K)

Approach EBP

Light Gas Oil

Names Mode

Cn

Start a new case, select Advanced Peng-Robinson as the Thermodynamic Model, select Si as the unit set and then click the PIONA Slate button at the bottom of the Thermo Model form.

 TTPiona1.png

 When the PIONA Slate form is prompted add the information from the previous table.

TTPiona2.png

Now, the PIONA Slate is ready to be created. Click on the Create Slate button and the slate will be added to the selected property package.

Close the form and inspect the created components in the Thermo model form. Let’s pay attention to the Aromatic compounds; it can be that the first three compounds represent Aromatics with 6, 7 and 8 carbon numbers respectively.

TTPiona3.png

A reduction in errors in the off-gas and vent material balance can be achieved in models using PIONA slates by employing pure components for the initial carbon numbers in each structure group. Then, let’s add the following pure aromatic compounds: Benzene, Toluene, and Styrene; these three compounds have carbon numbers of 6, 7 and 8 respectively and can replace the first three components from the Aromatics slate.

Add the compounds to the property package and open the PIONA Slate form again and click once more in the Create Slate button. Re-creating the slate will check for pure compounds installed in the property package that have similar carbon numbers and chemical families and eliminate them from the slate.

Now take a look to the slate of Aromatic compounds that were re-created.

TTPiona4.png

It can be seen now that the first three aromatic compounds were eliminated and replaced by Benzene, Toluene, and Styrene in the slate; see that the number of compounds did not change since three PIONA slate pseudo components were eliminated and three pure components were added. Note that Benzene, Toluene, and Styrene were sorted from the list of the property package compounds to appear before the Aromatic compounds.

We can add more pure components to better represent the hydrocarbon slate. Add the following pure compounds to the property package.

Water

Ethane

1 Butene

Hydrogen

Propane

2 Butene

Oxygen

n-Butane

Acetylene

Nitrogen

isoButane

Methylacetylene

Carbon

Ethylene

1,3-Butadiene

Carbon Dioxide

Propylene

 

Methane

isoButene

 

Open the PIONA Slate form again and change the Name Mode and Suffix to BP and C respectively, and click once more in the Create Slate button. Now, sort the pure compounds in a way that they are grouped by chemical family and carbon number. After sorting, the resulting list of compounds looks like this:

TTPiona5.png

The next step is the creation of an Oil Source unit operation based on a naphtha feed. The following table shows the experimental data given for the naphtha feed:

Property

Value

Bulk H/C Ratio (Mole)

2.255

Bulk Density @ 60 F [kg/m3]

679.0

‘P’araffin (Mass) [%]

44.374

‘I’so-Paraffin (Mass) [%]

39.726

‘O’lefin (Mass) [%]

0.000

‘N’aphthene (Mass) [%]

12.200

‘A’romatic (Mass) [%]

3.700

TBP Curve (0% Volume) [C]

38.0

TBP Curve (10% Volume) [C]

52.0

TBP Curve (50% Volume) [C]

71.0

TBP Curve (90% Volume) [C]

113.0

TBP Curve (100% Volume) [C]

141.0

Temperature [C]

60.0

Pressure [atm]

1.0

Mass Flow [kg/h]

100.0

Start by adding an Oil Source unit operation to the flowsheet. This unit operation is located in the Oil Data Regressions menu from the Simulation tree.

TTPiona6.png

Since the H/C Ratio is given in mole, go to the Settings tab and change the basis of the H/C Ratio to Mole.

TTPiona7.png

Now, add all the experimental variables from the previous table to the Oil Source unit operation.

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Observe that the calculated and specified physical properties are not very different; however, the distillation curve results are different than the specified ones as it can be seen in the Distillation Curve tab.

TTPiona9.png

Now, click on the Regress Parameters button at the bottom of the form to get the best combination of slate pseudo components compositions that gives the best match between experimental and distillation data. Once the regression finishes look at the calculated physical properties as well as the distillation curve.

TTPiona10.png

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Observe the close agreement between calculated and experimental results for both physical properties and distillation data. Now, the Oil Feed produced in the Oil Source unit operation can be connected to any other unit operation of VMGSim.

Please contact your local VMG office for more information.

Herbert Loria, VMG Calgary 

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