SIM4ME Thermodynamics

8/10/2019 SIM4ME Thermodynamics

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Dynamic Simulation

Suite

SIM4ME

Thermodynamics

Invensys SimSci-Esscor

5760 Fleet Street, Suite 100,

Carlsbad, CA 92008


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Dynsim 4 2 : SIM4ME

Thermodynamics

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Table of Contents

Table of Contents

Components and Thermodynamics Overview ............................1

Components and Thermodynamics Window ..............................2

Library Tab.. ...................................................................................3

Petro Tab 4

Cut Set Tab ....................................................................................5

Assay Tab ...................................................................................6

Blend Tab....................................................................................8

Property Tab ................................................................................10

Slate Tab...................................................................................11

Method Tab ..................................................................................12

Local Thermo Tab........................................................................13

Local Flash Tab ...........................................................................14

Default Tab...................................................................................15

Special Packages ........................................................................17

GLYCOL Package.........................................................................................17

Field Descriptions/Miscellaneous ..............................................19

Component Family List.................................................................................. 20Component Full Name...................................................................................21SIMSCI Name................................................................................................22Formula.......................................................................................................... 23Filter...............................................................................................................24Most Commonly Used ...................................................................................25PROCESS Databank.....................................................................................26SIMSCI Databank..........................................................................................27Hydrocarbon Lightends .................................................................................28Standard Liquid Density ................................................................................29Molecular Weight...........................................................................................30

Characterization Options...............................................................................31Default ........................................................................................................... 32Lee-Kesler .....................................................................................................33Cavett ............................................................................................................ 34SIMSCI .......................................................................................................... 35Extended API................................................................................................. 36Distillation Data Type.....................................................................................37Pressure ........................................................................................................ 38Volume (Weight) Percent Distilled vs. Temperature Table...........................39

Average Value............................................................................................... 40

SIM4ME Thermodynamics Contents - 1


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Table of Contents

Volume Percent Distilled vs. Gravity Table ...................................................41Extrapolation to end points............................................................................42Lightends Data Amount.................................................................................43Basis..............................................................................................................44Library Component vs. Relative Amount table..............................................45Normalize Lightends......................................................................................46

Average Value............................................................................................... 47Volume Percent Distilled vs. Inspection Property .........................................48

Watson K Factor............................................................................................49Assay vs. Relative Amount table...................................................................50Equilibrium Methods...................................................................................... 51Enthalpy Calculations....................................................................................52Entropy Calculations......................................................................................53Density Calculations...................................................................................... 54Transport Data...............................................................................................55Kinematic Viscosity Calculation Methods......................................................56Thermal Conductivity.....................................................................................57Petroleum Correlation Viscosity Estimation ..................................................58Petroleum Correlation Thermal Conductivity Estimation...............................59Refinery Inspection Properties ......................................................................60Calculation Mode for Local Flash.................................................................. 61Use Model Prediction ....................................................................................62Force Local Thermo ...................................................................................... 63Force Rigorous Thermo ................................................................................64Use Model Prediction ....................................................................................65Force Local Flash..........................................................................................66Force Rigorous Flash ....................................................................................67Component Slate...........................................................................................68Cut Set...........................................................................................................69Method Slate .................................................................................................70Standard Conditions...................................................................................... 71Peng-Robinson..............................................................................................72Peng-Robinson - Modified Panagiotopolous-Reid ........................................73

Peng-Robinson-Panagiotopoulos-Reid.........................................................74Soave-Redlich-Kwong................................................................................... 75SRK-Kabadi-Danner...................................................................................... 76SRK-Modified Panagiotopoulos-Reid............................................................77SRK-SIMSCI.................................................................................................. 78Redlich-Kwong .............................................................................................. 79Braun K10......................................................................................................80Grayson-Streed .............................................................................................81Curl-Pitzer method.........................................................................................82Johnson-Grayson ..........................................................................................83

API Liquid Density .........................................................................................84Ideal ...............................................................................................................85SIMSCI Databanks........................................................................................86

User-Prepared Databanks.............................................................................87User-Defined Petroleum Components ..........................................................88Assay.............................................................................................................89IUPAC............................................................................................................90Normal Boiling Point (NBP) ...........................................................................91

Assay Name ..................................................................................................92Cut Set...........................................................................................................93Enter Data For ............................................................................................... 94Cubic Spline ..................................................................................................95Quadratic Polynomials................................................................................... 96



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Table of Contents

Probability Density Function..........................................................................97API 1987........................................................................................................ 98API 1963........................................................................................................ 99Edmister-Okamoto.......................................................................................100Constant Watson K from TBP Curve...........................................................101Constant Watson K from D86 Curve ...........................................................102Liquid Volume Average ...............................................................................103

Temperature Midpoint .................................................................................104Initial and Final Points .................................................................................105PDF.............................................................................................................. 106Temperature Profile.....................................................................................107Start Temp/End Temp Table .......................................................................108

API Method..................................................................................................109Index Mixing Method ...................................................................................110SimSci Mixing Method.................................................................................111Summation Mixing Method..........................................................................112

Average Value.............................................................................................113Volume Percent Distilled vs. Molecular Weight Table................................. 114Default ......................................................................................................... 115Modular Thermo - Transport Data...............................................................116Normal Melting Point ...................................................................................117Customize the Property Tab........................................................................118Distillation Data............................................................................................119Temp............................................................................................................ 120Fluid Flowrate .............................................................................................. 121Distillation Types .........................................................................................122Pressure () ...................................................................................................123Pressure Basis ............................................................................................124Cracking ......................................................................................................125Rate .............................................................................................................126Fraction........................................................................................................127Percent ........................................................................................................ 128Match TBP Curve ........................................................................................129

COSTALD....................................................................................................130RACKETT....................................................................................................132



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Components and Thermodynamics Overview

Components and Thermodynamics Overview

Dynsimprovides considerable flexibility for defining components and allows you to construct

customized thermodynamic method slates.

The component data can originate from various sources such as the following: SIMSCI databanks

User-prepared databanks

User-defined petroleum components

Cut Sets

Components derived from petroleum assay data

Assay blends

There is no limit to the number of components that you can select for a flowsheet; however,

solution time improves when you keep the component slate size to a minimum.

You can assign different component slates and thermodynamic methods to specific unit

operations, but you must use a Basis Changer unit operation to connect unit operations using

different thermodynamic methods.

The current version of SIM4ME does not support component slate or thermodynamic method

propagation. When you place a new unit operation on the flowsheet, the new unit is assigned the

default component slate and thermodynamic method (as specified in the Defaultswindow). If you

assign a non-default component slate to a unit operation, units downstream donotautomatically

inherit the slate and method of the upstream unit.

Note:There are no preset defaults for thermodynamic methods and correlations.

When you first construct a SIM4ME flowsheet, you must specify the individual thermodynamic

methods and correlations to be used to calculate the various properties.

SIM4ME Thermodynamics Version 4.2, October 2006 1


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Components and Thermodynamics Window

Components and Thermodynamics Window

The Components and Thermodynamics window contains the Selected Components Tree and a

set of nine tabs. These tabs and their functions are:

Library Petro

Cut Set

Assay

Property

Slate

Method

Local Flash

Default

The Selected Components Tree shows all of the components that have been selected. These can

include the following:

SIMSCI databanks

User-prepared databanks

User-defined petroleum fractions

Petroleum pseudocomponents derived from assay data, and blends of petroleum

pseudocomponents.

There is no limit to the number of components that can be included in this tree. A few operations

simple operations can be performed directly on the tree:

Drag components around to change their order.

Delete or rename components by selecting, clicking the right mouse button, and choosingeither Delete or Rename.

The majority of the data entry operations take place on the individual tabs.

There is an Apply button on the window along with the normal OK, Cancel, and Help buttons.

Pressing Apply saves all of the data entered thus far (like clicking OK), but you will remain in the

GUI so you can make additional changes. You can think of Apply as being the same as clicking

OK, then immediately entering the thermo GUI again. Any changes you made before clicking

Apply will NOT be undone if you subsequently click Cancel; only changes made after clicking

Apply will be undone.



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Library Tab

Library Tab

This tab allows you to enter components from preexisting libraries to the Selected Components

Tree.

Library Componentsare represented in the Selected Components Treeby the benzene ring icon.To select a component from a preexisting list:

1. Use the Component Familypull down list to select a family type.

2. Double-click on a Component Full Name, or select one or more components and drag them

to theSelected ComponentsTree.

To add a component directly to the Selected Components list, enter the SIMSCI name in theAdd

Library Componentbox, then hit Enter or click Add.

Use the Filterfunction to assist you in limiting the Component Full Namesshown.

You can delete and rename items in the Selected Componentslist by right-clicking them.



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Petro Tab

Petro Tab

Use this window to add Petro Components (petroleum fractions) to the Selected Components

Tree. Define at least two of the thermodynamic properties for each petro component you add.

Petro components are represented in the Selected Components Treeby the oil drum icon. A red X

appears on the icon when data are incomplete.

1. Enter values for at least two of the following:

Normal Boiling Point

Standard Liquid Density

Molecular Weight

Characterization Option

2. Click Characterize All Petro Components.

SIM4ME uses internal correlations to estimate the third parameter if missing.

To add a component to the Selected Components Tree:

Enter a name in theNew Petro Componentfield and hit Enter or click Add.

The name appears in the left column of the table and is automatically included in the Selected

Components Tree.



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Cut Set Tab

Cut Set Tab

Use this window to add or modify True Boiling Point Cut Sets.

To add a new Cut Set:

1. Enter a name in theNew Cut Setfield and hit Enter or click Add.

2. Select a method for entering the Temperature profile.

3. Enter the data in the grid.

To select or update a Cut Set:

1. Use the Cut Set Namepull down list to select a name.

2. Change the Temperature profile and/or the data.

3. Click Update Selected Cut Setto see a real-time update of the input values. The values are

updated under any circumstances once you leave the tab.



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Assay Tab

Assay Tab

Use this window to enter assay characterization data.

For many petroleum feedstocks, the composition is not completely known in terms of defined

components. Thus, laboratory assay curves must be used to represent these streams bypseudocomponents (boiling point cuts) for which the necessary thermophysical properties can be

estimated.

Assay curves can include laboratory distillation, gravity, molecular weight, predefined special

properties, such as pour point and viscosity, and user-defined special properties. Assay curves can

be supplied on either a liquid volume % or weight % distilled basis.

The minimum information required to characterize any stream is a laboratory distillation and the

average gravity or Watson K Factor.

For many petroleum streams, the composition of the lightest portion is determined from a

chromatographic analysis. The known components can be supplied as Lightends data and used

directly to characterize the front portion of the distillation curve.

The number of pseudocomponents to use in characterizing a petroleum stream is defined with a

TBP Cut Set (Cutpoint set), where the number of components is defined for one or more

temperature intervals on the TBP curve.

Assays are represented in the Selected Components Treeby the Assay Curve icon.

To create a new assay:

Enter the assay name in this field and hit Enter or click Add.

The assay name appears in theAssay Namefield and in the Selected Components Tree.

To enter assay data:

1. Use the pull down list to select the Assay Name.

2. Optionally modify the:

Cut Set

Method Slate

3. Enter data for:

Distillation

Type

Pressure

Volume (Weight) Percent Distilled vs. Temperature Data. Right-click on the Percent

Distilled column header to switch between Volume and Weight percent.

Gravity

Average Value (required)

Percent Distilled vs. Gravity Table (optional)

Molecular Weight (optional)

Average Value

Percent Distilled vs. Molecular Weight Table



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Assay Tab

Lightends

Drag one or more library components from the Selected Components Treeand drop

them into the table.

Enter relative amounts for each.

By default, the assay will match your lightends composition to the assay data. You

can also select Fraction (or Percent) to indicate that your amounts are actual fractions

(percents). If you do this you can also enter the overall lightends fraction (percent).

Inspection Properties

Select one of the inspection properties.

Enter either an Average Value, or enter a property curve in the table.

4. Click Process Selected Assayto perform the assay cutting and characterization. You can

then see the properties of the individual cuts in the Property tab.



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Blend Tab

Blend Tab

Use this tab to create Blends of Petroleum Assays.

A Blend can be used to configure and blend one or more assays in the desired proportions to

generate pseudo-components that would match in their characteristics with a stream obtainedfrom mixing the specified assays in the same proportion. The pseudo-components for petroleum

assays based on a given TBP Cut-Set can be averaged to produce a single set of blend

components that may then be used to represent the streams in the simulation.

The Components and Thermodynamics GUI allows multiple cut-point sets to be used in any

simulation to define multiple blends of pseudo-components. This is useful when petroleum

streams are dissimilar and one set of blend components is not adequate to represent all streams.

Assays are represented by the Assay curve icon in the selected components list.

Blends are represented in the Selected Components list by the Blend icon.

Incompletely specified a Blend icon represents Blends with a Red cross on it.

Note: To create a Blend, it is required to have a defined Cut-set and a minimum of one Assay inthe Selected Component list. The user may create separate Method slates to be used for different

Blends.

To create a new blend:

Enter the name for the new blend in the New Blendfield and click Add or press Return. The

blend name appears in the Blend Namefield and in the Selected Componentslist.

From the Cut-Setdrop-down list, select a Cut-Set upon which the new blend is to be based.

Drag one or more Assays from the Selected Components list and drop them into thefirst cell

in the Assay or Blendscolumn. Additional rows are automatically created to accommodate

the number of Assaysbeing added.

Specify whether the Blend Basis is to be by Weight or Liquid Volume.

Enter the fractional relative amounts of each Assayin the cells in the Relative Amount

column. The amounts should total to 1.00. Otherwise, the relative amount values will be

normalized.

To delete/rename a blend:

Right-click on the Blend in the Selected Componentslist to display a menu of options.

Blend Name(drop-down)

Use this drop-down list to select the Blend Name to be used for the current simulation.

Cut-Set(drop-down)

Use this drop-down list to select the Cut-Set to be used for the current blend.



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Blend Tab

MethodSlate (drop-down)

Use this drop-down list to select the Method slate to be used for the current blend.

An illustration of the Blends Tab after creating a Blend:

Blend Basis

Choose whether the Blend Basis is to be by Weight or Liquid Volume.

Normalize

Check this option to normalize the amounts of Assays if they do not sum to 1.00.

Assay and Relative Amounts Table

Use this table to add Assaysto a Blendand to specify their relative amounts.

Initially, this table contains only a single row.

To enter data for this table:

Drag one or more Assaysfrom the Selected Componentslist and drop them into the first cell

in theAssay or Blendcolumn. Additional rows are automatically created to accommodate the

number of Assays being added.

Enter the fractional relative amounts of each Assay in the cells in the Relative Amounts

column. The amount should total to 1.00. If not, Thermo will normalize the amounts.

To delete anAssay:

Right-click on the cell containing the name of the Assayand click Delete.



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Property Tab

Property Tab

This tab allows you to view the values of the fundamental properties of the components. For

Library and Petro components, you can also change these values.

Properties are arranged in tables. The drop down list at the top allows you to select the table toview.

To change the units-of-measure, right-click on a column header. To change a property value,

enter a new value. User entered values are blue bordered. Delete the cell contents to restore the

original.

The Customize button is use to create or modify your own tables. Drag properties from the list at

the bottom of the tab into the column headers in the dummy grid. Then save the table. The name

you choose when you save will now appear in the drop-down list at the top of the tab. Click

Close to exit customize mode and return to the normal tab.

Note that you CANNOT modify or delete the tables provided in the install, but you can loadthem, modify them, and save them under another name.



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Slate Tab

Slate Tab

Use this tab to create or modify component slates.

New Component Slate

To create a new Component Slate:

1. Enter the name for the new slate in the New Component Slate field and click Add or press

Return.

The slate name appears in the Slate Name field.

2. Drag one or more Components, Assays or Blends from the Selected Components list and

drop them into Components in Slate list. A tree structure similar to that in the Selected

Components list is replicated.

To remove a Component, Assay or Blendfrom the Components in Slatelist:

1. Select the item in the list.

2. Right-click on the item and click Remove.

To remove a fraction from an Assay:

Expand the Assayto display its fractions.

1. Select the fraction in the list.


Slate Name

This drop-down list contains the names of the currently defined Component Slates.

Components in Slate

To add Components, Assays or Blends to a Component Slate:

Drag one or more Components, Assaysor Blendsfrom the Selected Componentslist

and drop them into the Components in Slatelist.

To remove a Component, Assayor Blendfrom the Components in Slatelist:

1. Select the item in the list.


To remove a fraction from an Assay:

Expand the Assayto display its fractions.

1. Select the fraction in the list.




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Method Tab

Method Tab

Use this window to modify or create thermodynamic method slates. There are no defaults for

thermodynamic methods and correlations. Specify the individual thermodynamic methods and

correlations to be used to calculate the various properties.

For example, if you expand the tree, the following subcategories are displayed:

Thermodynamic Data

Equilibrium

Enthalpy

Entropy

Density

Transport Data

Viscosity

Thermal conductivity

Inspection Property Data

Content Properties

Point Properties

To create a New Method Slate:

Enter the name in theNew Method Slatefield and hit Enter or click Add.

The new slate name appears in theMethod Slatesdrop down list.

To select a Method Slate:

Use theMethod Slate Namepull down list that contains the names of the currently

defined Thermodynamic Method Slates.

To select an Enthalpy (or other) calculation method for all phases at once:

Select the subcategory Enthalpy and right-click to display the options.

To select an Enthalpy (or other) calculation method for each phase individually:

1. Expand the Enthalpy subcategory.

2. Specify a different method for each phase by selecting it, then right clicking to display the

appropriate options.

When you select a method for calculating an RIP, additional data entry fields may appear at the

bottom of the tab.



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Local Thermo Tab

Local Thermo Tab

This tab allows you to enter a new Local Thermo Option or edit an existing Local Thermo

Option. The existing Local Thermo Options can be seen in the pull down listLocal Thermo

Options Name.

To add a new Local Thermo Option:

1. Enter a name in theNew Local Thermo Optionsfield.

2. Click Add.

This will add the new Local Thermo Option entered to theLocal Thermo Options Namelist.

Each Local Thermo Option is associated with one of the following three Calculation Modes:

Use Model Prediction - the model will determine when to use the rigorous flash and when to

use a local approximation.

Force Local Thermo - to force use of the local approximation always.

Force Rigorous Thermo - to force use of the rigorous flash always.

By default Use Model Predictionwill be associated with any new Local Thermo Option created.

The user has to exclusively select, if desired so, the other two options.

To edit an existing Local Thermo Option:

1. Select the Local Thermo Option from the Local Thermo Options pull down list.

2. Modify the relative and absolute tolerances for Temperature and Pressure in the Windows

Check Size window.

3. Modify "Second Order Error" to specify the maximum error and also select an option from

the drop down list in the Use Composition Effect column for composition effect.

4. Click Apply.



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Local Flash Tab

Local Flash Tab

This tab allows you to create a new Local Flash Option or edit an existing Local Flash Option.

The existing Local Flash Options can be seen in the pull down listLocal Flash Options Name.

To add a new Local Flash Option:1 Enter a name in theNew Local Flash Optionsfield.

2 Hit Enter or click Add.

This will add the new Local Flash Option entered to theLocal Flash Options Namelist.

Each Local Flash Option is associated with one of the following three Calculation Modes:

Use Model Prediction the model will determine when to use the rigorous flash and

when to use a local approximation.

Force Local Flash - to force use of the local approximation always.

Force Rigorous Flash - to force use of the rigorous flash always.

By default Use Model Predictionwill be associated with any new Local Flash Option created.The user has to exclusively select, if desired so, the other two options.

To edit an existing Local Flash Option:

1 Select the Local Flash Option from theLocal Flash Options Namepull down list.

2 Modify Second order error to specify the maximum error before a model update will

occur.



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Default Tab

Default Tab

Use this tab to set default PseudocomponentandAssay Characterizationoptions,Distillation

Boundaries,DataandMethodsoptions. Also use it to choose the Standard Conditionsfor the

flowsheet.

This tab consists of the following areas:

Pseudocomponent Characterization Option

Choose one of the following as the default characterization method to predict a missing third

parameter of a pseudocomponent:

SIMSCI

Cavett

Lee-Kesler

Extended API

Unless changed locally on the Petro tab, the default method is used automatically in subsequent

pseudocomponent characterization.

Assay Characterization Options

These include:

Fitting Procedure

Distillation Curve Interconversions

Gravity Curve Generation Method

Calculation of NBP for Cuts.

Fitting Procedure

Curve fitting procedures are used to extrapolate and interpolate distillation data supplied for an

assay. Curve fitting produces a smoothed distillation curve that can be integrated to determine the

average boiling points for the pseudocomponents.

The following three curve fitting methods are available:

Cubic Spline

Quadratic Polynomials

Probability density function

Distillation Curve Interconversions

All assay distillation curves must be converted to a 760 mm Hg TBP basis before use in

determining the pseudocomponent normal boiling points. Modular Thermo provides three

Interconversionoptions:

API 1987

API 1963

Edmister-Okamoto

Gravity Curve Generation Method

When a gravity curve is not provided for an assay stream, the gravities for the pseudocomponents

must be generated using one of the techniques described below.

Constant Watson K from TBP Curve

Constant Watson K from D86 Curve

Calculation of NBP for Cuts



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Default Tab

Choose this option to determine which method is used to calculate the Normal Boiling Point of

narrow cuts.

Liquid Volume Average

Temperature Midpoint

Distillation Boundaries

These include:

Initial and Final Points

PDF(Probability Density Function)

Default Selections

Component Slate

Method Slate

Cut Set

The default Component Slate and Method Slate will be assigned to any new unit operations

you create. The default Cut Set will be used by any new assays you create.

Standard ConditionsThe definition of standard conditions is the basis for some of the Thermo calculations. These

parameters are used for stream special property calculations such as calculating Standard Vapor

flow rates and Density. They do not represent actual atmospheric conditions. Select from the

drop-down list either:

Pre-defined standard conditions, or

Custom option and enter your standard T and P directly.



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Special Packages

Special Packages

GLYCOL Package

The glycol data package uses the SRKM equation of state to calculate phase equilibria for glycoldehydration applications. This system uses a special set of SRKM binary interaction data and

alpha parameters for systems containing glycols, water, and other components. The binary

parameters and alpha parameters have been obtained by the regression of experimental data for

glycol systems. The recommended temperature and pressure ranges for the GLYCOL package

are:

Temperature: 80-400 F

Pressure: up to 2000 psia

Other thermodynamic properties such as the vapor and liquid enthalpy, entropy, and vapor

density are calculated using the SRKM equation of state, while the liquid density is calculated

using the API method.

Table below shows the components present in the GLYCOL databank for which there are binary

interaction parameters available.

Components Available for GLYCOL Package

Components Formula LIBID

Hydrogen

Nitrogen

Oxygen

Carbon Dioxide

Hydrogen Sulfide

Methane

Ethane

Propane

Isobutane

N-butane

Isopentane

Pentane

Hexane

Heptane

Cyclohexane

Methylcyclohexane

Ethylcyclohexane

Benzene

Toluene

O-xylene

M-xylene

P-xylene

Ethylbenzene

Ethylene Glycol

Diethylene Glycol

H2

N2

O2

CO2

H2S

CH4

C2H6

C3H8

C4H10

C4H10

C5H12

C5H12

C6H14

C7H16

C6H12

C7H14

C8H16

C6H6

C7H8

C8H10

C8H10

C8H10

C8H10

C2H6O2

C4H10O3

H2

N2

O2

CO2

H2S

C1

C2

C3

IC4

NC4

IC5

NC5

NC6

NC7

CH

MCH

ECH

BNZN

TOLU

OXYL

MXYL

PXYL

EBZN

EG

DEG



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Special Packages

Triethylene Glycol

Water

C6H14O4

H2O

TEG

H2O

Figure below shows the binary interaction parameters, denoted by x, present in the glycol

databank. Interaction parameters denoted by o are supplied from the SRK databank. It should

be noted that for all pairs not denoted by x or o, the missing binary interaction parameters are

estimated using a molecular weight correlation, or are set equal to 0.0.

Figure - BINARY Interaction Data in the Glycol Databank



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Field Descriptions/Miscellaneous




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Component Family List

Categorizes components similarly to an organic chemistry textbook. If you know the structure of

a desired component, look for its family name in the family list. The component family can be

selected from the Component Familypull down list.

The Modular Thermo databanks contain the following general component collections:

Most Commonly Used

Hydrocarbon Light Ends

PROCESS Databank

SIMSCI Databank

In addition, the following specific chemicalfamilies have been grouped to allow you to quickly

create component slates:

Acids

Alcohols

Aldehydes Amides

Amines

Aromatic Hydrocarbons

Elements

Esters

Halogenated Derivatives

Ketones

Miscellaneous

Naphthenic Hydrocarbons Other Nitrogen Derivatives

Paraffin Hydrocarbons

Salts and Minerals

Silicon Derivatives

Sulfur Derivatives

Unsaturated Hydrocarbons.



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Component Full Name

Typically either the common name or IUPAC name for a component.



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SIMSCI Name

Used as a variable for process stream and thermodynamic calculations.

Enter a name of up to eight characters in length.



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Formula

This is a nonstructural chemical formula for the component, when appropriate.

Formulas for isomers are not unique.



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Filter

Enter alphanumeric text to limit the components shown in the Selected Components Tree list.



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Most Commonly Used

This component family comprises approximately 100 components representing the pure

components commonly encountered in natural gas and petroleum processing.



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PROCESS Databank

The PROCESS databank is the SIMSCI original databank of component physical properties. It

has only VL components and contains no VLS property data.

The SIMSCI Databank is newer.



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SIMSCI Databank

The SIMSCI database contains property data for about 1750 pure components.

It is newer than the PROCESS databank.



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Hydrocarbon Lightends

This list contains low molecular weight hydrocarbons and gases commonly found in oil refinery

streams. Compounds up to decane are included



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Enter Standard Liquid Density data in terms of specific gravity or API gravity.



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Molecular Weight

Enter the molecular weight.

The molecular weight is the most difficult property to predict accurately from generalized

correlations and should be supplied when possible for the most accurate characterization of a

Petro Component.



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Characterization Options

Select one of the following characterization methods to predict a missing third parameter:

Default

SIMSCI

Cavett Lee-Kesler

Extended API.

The Default method is established in the Defaults tab of this window by selecting one of the four

methods.



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Default

The Default method is established in theDefaults dialog boxby choosing one of the four listed

methods.

SIMSCI

Cavett

Lee-Kesler Extended API.



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Lee-Kesler

Method developed for Mobil Oil Company by B. I. Lee and M.G. Kesler.

Predicts pseudocomponent properties based on the component normal boiling point, gravity and

molecular weight.



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Cavett

Uses a nomogram from the 1967 API Technical Data Bookthat relates molecular weight, normal

boiling point and specific gravity. The molecular weight prediction for compounds with normal

boiling points lower than 300 F is predicted with a method developed by SIMSCI, based on pure

component data.



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SIMSCI

Estimates molecular weight for each petroleum component, based on its normal boiling point and

gravity. The molecular weights are derived by application of a correction factor to the molecular

weight for normal alkanes.



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Extended API

Uses an improved nomogram published in the 1980 API Technical Data Book, which relates

molecular weight, normal boiling point and specific gravity. The molecular weight prediction for

compounds with normal boiling points lower than 300 F is predicted with a method developed

by SIMSCI based on pure component data.



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Distillation Data Type

Select the distillation data analysis type from the following standard options:

True Boiling Point (Volume %)

ASTM D86 (Volume %)

ASTM D86 Cracking (Volume %)

ASTM D1160 (Volume %)

ASTM D2887 (Weight %)The heading of the Percent Distilledcolumn of the data entry table changes to reflect whether the

data is reported on a liquid volume % (TBP, D86 and D1160) or weight % (D2887) basis.



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Pressure

Enter the pressure at which the data for the distillation curve was collected if other than the

default pressure.

Default pressures are:

TBP 760 mm Hg

ASTM D86 760 mm HgASTM

D1160

10 mm Hg

ASTM

D2887

Chromatographic analysis



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Volume (Weight) Percent Distilled vs. Temperature Table

Enter data pairs for liquid volume (weight) % distilled vs. temperature in the respective columns.

The default upper and lower distillation boundaries for volume (weight) % distilled are 1% to

98%. The default distillation boundaries can be changed in the Defaults window.

If the distillation basis is other than the default for the method, you can change the basis from

volume % to weight % (or vice versa) by right clicking on the Percent Distilledcolumn headingto display a menu of options.



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Average Value

Enter the average gravity (as a specific gravity, API Gravity, or Watson K-Factor) for each assay.

If a Watson K is given, it is converted to a gravity using the TBP data for the curve. Entry of a

gravity curve is recommended but not required.

You can change the basis for the average gravity by right clicking on the heading of the Gravitycolumn in the data entry table to display a menu of options.



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Volume Percent Distilled vs. Gravity Table

Enter the % distilled (the mid-volume or mid-weight % of the data point) and corresponding

gravity values in the table.

The percents must be on the basis chosen for the distillation data (liquid volume orweight %)

The gravity values correspond to the gravity type selected (specific gravity, APIGravity, or Watson K-Factor).

At least three gravity points must be supplied to define the gravity curve.

You can change the basis for the gravity data entries by right clicking on the heading of the

Gravitycolumn to display a menu of options.

Options for the Gravity Curve Generation Methodare found in the Defaultswindow.

For details, see Extrapolation to end points.



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Extrapolation to end points

If a user-supplied gravity curve does not extend to the 95% point, quadratic extrapolation is used

to generate an estimate for the gravity at the 100% point. Gravity for each cut is determined at its

mid-point, and an average gravity for the stream is computed. If this average does not agree with

the specified average, the program either normalizes the gravity curve (if data are given up to

95%) or adjusts the estimated 100% point gravity value to force agreement. Since the latter couldin some cases result in unreasonable gravity values for the last few cuts, consider providing an

estimate of the 100% point gravity value and letting the program normalize the curve, particularly

when gravity data is available to 80% or beyond.



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Lightends Data Amount

Select one of the following Specificationoptions to determine the amount of lightends in the

assay:

Match TBP (default)

Fraction

Percent

By default, SIM4ME matches user-supplied lightend data to the TBP curve. The user-specified

rates for all lightend components are adjusted up or down, all in the same proportion, until the

NBP of the highest-boiling lightend component exactly intersects the TBP curve. All of the cuts

from the TBP curve falling into the region covered by the lightends are then discarded and the

lightend components are used in subsequent calculations.

Alternatively, you can specify the lightends as a fraction or percent (on a weight or liquid volume

basis) of the total assay or as a fixed lightend flowrate. In these cases, the supplied numbers for

the lightend components can be normalized to determine the individual component flowrates.



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Basis

Select one of the following Specificationoptions to determine the amount of lightends in the

assay:

Weight

Volume



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Library Component vs. Relative Amount table

Use this table to add Library Components to the assay and to specify their relative amounts.


To enter data for this table:

1. Drag one or more Library Components from the Selected Components Treeand drop theminto the cells in theLibrary componentcolumn.

Additional rows are automatically created to accommodate the number of components being

added. All Windows 95/NT selection options are supported.

2. Enter the fractional relative amounts of each lightend component in the cells in theRelative

Amountscolumn.

The amount should total 1.00. If not, SIM4ME normalizes the amounts.



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Normalize Lightends

Select this option to normalize the relative amounts of the lightend components if the amounts do

not sum to 1.00. TheNormalizeoption does not become available until you have entered a value

in the Lightends Amount data field.



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Volume Percent Distilled vs. Inspection Property

Enter the mid-volume % distilled and corresponding Inspection Property values for the cuts.

The curve generated from these data pairs is quadratically interpolated and extrapolated to cover

the entire range of pseudocomponents.

If you also supply an average molecular weight in addition to the data pairs, the Inspection

Property value for the last cut is adjusted so that the curve matches the given average.



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Watson K Factor

The Watson K Factor is defined as:

where

NBP = component or stream average normal boiling point (R)

Sp.Gr. = component or stream average normal boiling point at 60F

relative to water at 60F



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Assay vs. Relative Amount table

Use this table to add assays to a blend and to specify their relative amounts.


To supply data for this table:

1. Drag one or more assays from the Selected Components Treeand drop them into the last cellin theAssaycolumn.

Additional rows are automatically created to accommodate the number of assays being added.

2. Enter the fractional relative amounts of each assay in the cells in theRelative Amounts

column.

The amount should total to 1.00. If not, Modular Thermo normalizes the amounts.

To delete an assay:

Right-click on the cell containing the name of the assay and click Delete.



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Equilibrium Methods

Modular Thermooffers the following options for equilibrium calculation methods:

Peng-Robinson

Peng-Robinson-Modified Panagiotopolous-Reid

Peng-Robinson-Panagiotopoulos-Reid

Soave-Redlich-Kwong SRK-Kabadi-Danner

SRK-Modified Panagiotopoulos-Reid

SRK-SIMSCI

Redlich-Kwong

Braun K10

Grayson-Streed



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Enthalpy Calculations

Modular Thermo offers the following options for enthalpy calculations:

Soave-Redlich-Kwong

Curl-Pitzer

Johnson-Grayson



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Entropy Calculations

Modular Thermo offers the following options for entropy calculation methods:

Soave-Redlich-Kwong

Curl-Pitzer



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Density Calculations

Modular Thermo offers the following options for Density calculation methods:

Soave-Redlich-Kwong

API Liquid Density

Ideal



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Transport Data

Most pure library components include saturated vapor and liquid values for viscosity and thermal

conductivity as part of the general thermodynamic properties database.

Pure-Component Average

Petroleum Correlation Method

Transport Data Pure-Component AverageChoose this method to compute transport properties as a weighted average of pure-component

values. This method requires that the property in question be available for each component in the

mixture with the exception of petroleum pseudocomponents.

The pure-component properties at the temperature of interest are combined to calculate stream

average properties according to the mixing rules.

Transport Data - Petroleum Correlation MethodChoose this method to apply a petroleum correlation method to all components in the stream.

Modular Thermo estimates the above properties from correlations for pseudocomponents.



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Kinematic Viscosity Calculation Methods

Modular Thermooffers the following options for Kinematic Viscosity calculation methods:


Petroleum Correlation

Kinematic Viscosity - Pure-Component AverageThis method computes the kinematic viscosity of a stream as a weighted average of

pure-component viscosities. The pure-component method requires that the viscosity be available

for each component in the stream with the exception of petroleum pseudocomponents.

Saturation values are used and no pressure corrections apply.

This method is available for both vapor and liquid viscosity calculations.

Kinematic Viscosity - Petroleum CorrelationThis method employs predictive correlations that apply to bulk hydrocarbon mixtures. The

correlations are applied to pure components as well as pseudocomponents. Pressure corrections

apply.This method is available for both vapor and liquid kinematic viscosity calculations.

For details, see Petroleum Correlation Viscosity Estimation.



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Thermal Conductivity

Modular Thermooffers the following options for thermal conductivity calculation:


Petroleum Correlation

Thermal Conductivity - Pure-Component AverageApplies simple mixing rules to the temperature-dependent values of pure components to calculate

thermal conductivity properties of mixtures.

Saturation values are used and no pressure corrections apply.

This option is available for both vapor and liquid viscosity calculations.

Thermal Conductivity - Petroleum CorrelationUses predictive correlations that apply to bulk hydrocarbon mixtures.

This option is available for both vapor and liquid conductivity calculations.

For details, see Petroleum Correlation Thermal Conductivity Estimation.



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Petroleum Correlation Viscosity Estimation

Vapor Viscosity

See:

Thodos, G., and Yoon, 1970, Viscosity of Nonpolar Gaseous Mixtures at Normal Pressures,

AIChE J., 16, 300-304.

Dean, D.G., and Stiel, L.S., 1965, The Viscosity of Nonpolar Gas Mixtures at Moderate and HighPressures,AIChE J., 11, 526-532.

Liquid ViscosityWhen the system is near the critical point (0.98


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Petroleum Correlation Thermal Conductivity Estimation

Vapor Thermal ConductivityModular Thermo employs the Roy-Thodos method to determine vapor thermal

conductivities.

The function of temperature used is the one that is presented by the authors for saturated

hydrocarbons. This method is corrected for pressure effects using the equations of Stiel andThodos.

Liquid Thermal ConductivityThe Sato and Reid method is used to calculate liquid thermal conductivity.



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Refinery Inspection Properties

Modular Thermooffers calculation methods for the following Refinery Inspection Properties:

Property Available Methods

Carbon Content Summation, Index, SimSci

Hydrogen Content Summation, Index, SimSci

Nitrogen Content Summation, Index, SimSciOxygen Content Summation, Index, SimSci

Iron Content Summation, Index

Nickel Content Summation, Index

Wax Content Summation, Index

Sulfur Content Summation, Index

Freeze Point Summation, Index, User Formula

Cloud Point Index, SimSci, User Formula

Flash Point Index, SimSci, API, User Formula

There are many more properties available. Select a property and provide a method.

For details on the methods listed above, refer to:

API Index

SimSci

Summation

User Formula



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Calculation Mode for Local Flash

There are three Calculation Modesavailable for Flash:

Use Model Prediction

Use Local Flash Use Rigorous Flash



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When the Use Model Prediction option is selected, the model based on certain criteria selects

either Local Thermo or Rigorous Thermo during the simulation run time. For the Use Model

Prediction option, check for the following:

Window Check SizeThe Window Check Sizedefines an operating region for Local Flash around a reference point.

Relative and Absolute tolerances for Pressure and Temperature are used to define the operating

range. During execution, if the local property deviation crosses the operating region, a Check

is made if the property is still continuous with respect to the reference. If a discontinuity is

detected, then the property is updated by making a rigorous call. If the property is still

continuous, then the window is extended to the next deviation interval.

The default values for relative tolerance for both Pressure and Temperature are 0.1. The default

values for absolute tolerance for Pressure and Temperature are 30 K and 100 kPa respectively.

The user is free to modify these values. However, the greater the window check size, the less

number of checks are made by the local model. This results in a higher probability of notdetecting a discontinuity and greater risk for flowsheet instability. The smaller the window check

size, the more number of checks are made by the local model. However, this will enable to detect

a discontinuity faster. Hence it is a trade off between model speed and model stability. The user

needs some level of experience for setting these tolerance limits. However, the default values

work quite well under most situations.

Defining Second Order Fraction and Use Composition OptionLocal Thermo uses a Second Order Taylor series expansion to predict local properties. The

differences between the first order terms and the second order terms in the expansion give an

excellent approximation of the true error in the model. The update criterion is triggered if the

second order terms exceed the specified second orderfractional error with respect to the first

order terms.

The tolerance limit for second order fractional error can be defined in the Second Ordercolumn.

The default value is 0.15 for this fractional error. However, the user can modify this value.

The user also has the choice as whether to include or not composition effect in the Taylor Series

Expansion. The user can make this choice by selecting either on or off option from the pull

down menu in the Use Composition Effectcolumn.



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Force Local Thermo

When this option is selected, Local Thermo is forced all the time during the simulation run.



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Force Rigorous Thermo

When this option is selected, Rigorous Thermo is forced all the time during the simulation run.



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When this option is selected, the model uses its own judgment based on certain criteria to select

between Local Flash and Rigorous Flash at a particular point of time during the simulation run.

When Use Model Predictionis used as the Calculation Mode, the user needs to define a tolerance

limit on the second order fractional error for Temperature, Pressure and Composition.

The tolerance limit for second order fractional error can be defined in the Second Ordercolumn.

The default value is 0.15 for this fractional error. However, the user can modify this value.



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Force Local Flash

When this option is selected, Local Flash is forced all the time



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Force Rigorous Flash

When this option is selected, Rigorous Flash is forced all the time.



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Component Slate

Use this drop down list to choose a default component slate from the list of previously defined

slates.

The default component slate is automatically applied to all units and streams subsequently placed

on the flowsheet.

You can also change the component slate at the local level when creating new units and streams.



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Cut Set

Use this drop down list to choose a default Cut Set from the list of previously defined Cut Sets.

The default Cut Set automatically is applied to all subsequent blends.

You can also change the Cut Set at the local level when creating new blends.



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Method Slate

Use this drop down list to choose a default thermodynamic method slate from the list of

previously defined slates.

The default method slate is automatically applied to all units and streams subsequently placed on

the flowsheet.

You can also change the method slate at the local level when creating new units and streams.



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Standard Conditions

Choose from the three predefined options for Standard Temperatureand Pressure Conditionsfor

the standard molar volume calculations or manually add temperature and pressure conditions.

The default temperature is 60 F (English) and the default pressure is 1.0 atmosphere.

The standard volume occupied by one mole of vapor at standard temperature and pressure.

The default values are: English

379.49 ft3/lb Mole at 60 F, 1.0 atmosphere

Metric, SI22.414 m3/Kg Mole at 0.0 C, 1.0 atmosphere (Metric, SI)



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Peng-Robinson

The Peng-Robinson (PR) equation of state (EOS) is a 1976 modification of the Redlich-Kwong

EOS. PR is similar to the Soave-Redlich-Kwong equation and was designed to improve the poor

liquid density predictions for the SRK method.

Peng-Robinson has been found to give accurate predictions for non-polar mixtures ofhydrocarbons. It does not give accurate predictions for polar components.

Hydrogen phase behavior is approximated by Peng-Robinson using a modified acentric factor.

In addition to K-values, the PR equation can be used to predict the enthalpies, entropies and

densities for the liquid and vapor phases. The predicted liquid phase densities are not very

accurate and the API method is suggested when the PR system is chosen.



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Peng-Robinson - Modified Panagiotopolous-Reid

This method, PRM, is a modification of the mixing rule for the PR-Panagiotopoulos-Reid by

SIMSCI in which two more adjustable parameters, cij and cji are introduced. This improves the

prediction for polar-nonpolar systems, where the nonideality is large or strongly asymmetric.

SIMSCI has fit many binary systems of chemicals to this equation and the parameters are

supplied in Modular Thermo.

The PRM method in Modular Thermo uses an improved correlation developed by SIMSCI that

provides more accurate vapor pressure predictions than the original PR formulation for a wide

range of components.

In addition to K-values, the PRM equation can be used to predict the enthalpies, entropies and


accurate and the API method is suggested when this system is chosen.



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Peng-Robinson-Panagiotopoulos-Reid

This method (PRP) is a modification of the Peng-Robinson method in which an asymmetric

mixing rule containing two parameters is used in determination of the "a (T)" term in the PR

equation. Two adjustable interaction parameters are used, kij and kji. This significantly improves

the accuracy of predictions for mixtures of polar and non-polar components. The mixture rule is

flawed, however, in that it is not invariant to dividing a component into a number of identicalpseudocomponents.

The PRP method in Modular Thermo uses an improved alpha correlation developed by SIMSCI.

The improved correlation provides more accurate vapor pressure predictions than the original PR

formulation for a wide range of components.

In addition to K-values, the PRP equation can be used to predict the enthalpies, entropies and





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Soave-Redlich-Kwong

The Soave-Redlich-Kwong equation of state (SRK) is a modification of the Redlich-Kwong

equation of state (which is based on the van der Waals equation) and was published by Georgi

Soave in 1972.

This equation has been found to give accurate predictions for non-polar mixtures ofhydrocarbons. It does not give accurate predictions for polar components.

Modular Thermo contains correlations for kij's for systems with hydrocarbons and N2, H2S

and O2. Some kij's are also provided for hydrocarbon splits such as ethane-ethylene and

propane-propylene. Hydrogen phase behavior is approximated by SRK using a modified acentric

factor. Other methods, which modify the alpha formulation, give more accurate predictions for

hydrogen than the original SRK formulation.

In addition to K-values, the SRK equation can be used to predict the enthalpies, entropies and


accurate and the API method is suggested when the SRK system is chosen.



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SRK-Kabadi-Danner

This method (SRKKD) is a modification of the Soave-Redlich-Kwong method to improve the

prediction of vapor-liquid-liquid phase equilibria for hydrocarbon systems with water. To achieve

this, Kabadi and Danner proposed a two parameter-mixing rule for calculation of the "a (T)" term

in the SRK equation. They also developed a means to provide estimates for water-hydrocarbon

equilibria when no data is available.

The SRKKD method in Modular Thermo uses an improved alpha correlation developed by

SIMSCI that provides more accurate vapor pressure predictions than the original SRK

formulation for a wide variety of components.

In addition to K-values, the SRKKD equation can be used to predict the enthalpies, entropies and





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SRK-Modified Panagiotopoulos-Reid

This method (SRKM) is a modification of the mixing rule for the SRK-Panagiotopoulos-Reid by

SIMSCI, in which two more adjustable parameters cij and cji are introduced. This improves the

prediction for polar-nonpolar systems, where the nonideality is large or strongly asymmetric.

SIMSCI has fit many binary systems of chemicals to this equation and the parameters are

supplied in PRO/II.

The SRKM method in Modular Thermo uses an improved alpha correlation developed by SimSci

that provides more accurate vapor pressure predictions than the original SRK formulation for a

wide variety of components.

In addition to K-values, the SRKM equation can be used to predict the enthalpies, entropies and





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SRK-SIMSCI

This method (SRKS) uses a new mixing rule to eliminate the flaw in the original

Panagiotopoulos-Reid mixing rule. Four adjustable parameters are used, with the mixing

rule designed to produce good results for mixtures of polar and nonpolar compounds.

The SRKS method in Modular Thermo uses an improved alpha correlation developed bySIMSCI. The improved correlation provides more accurate vapor pressure predictions than the

original SRK formulation for a wide variety of components.

In addition to K-values, the SRKS equation can be used to predict the enthalpies, entropies and



Suitable for three phase separators for water-hydrocarbon systems such as those found in FCC

gas plants and hydrocrackers, lube oil and solvent dewaxing units, natural gas systems containing

polar compounds such as methanol and any chemical operations for which the parameters can be

determined by regression.



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Redlich-Kwong

Redlich-Kwong is a specific case of the generalized two-parameter cubic equation of state of the

form:

where

P= pressure

T = absolute temperature

v= moral volume

u, w= constants (typically integers)

By setting u = 1 and w = 0, the Redlich-Kwong equation is obtained.

For derivation of the values for aandb, see the Redlich-Kwong in the Technical Reference.



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Braun K10

The Braun-K10 method (BK10) is based on the charts developed by Cajander, ET. Al., in 1960.

The chart for a convergence pressure of 5000 psia is used to predict the component K-values at a

system pressure of 10 psia. The K-values at 10 psia are ratioed to the desired pressure.

This method has limited capability to predict the K-values for light components and uses grossapproximations for H2, N2, O2, CO, CO2 and H2S. For aromatic compounds, a vapor pressure

correlation is used for K10 values of 2.5 or less. Pseudocomponents are estimated using a

correlation of K10 values and boiling points.

This method usually gives reasonable results for refinery heavyendcolumns operating at low

pressures. If the lightends distribution in the column is important, another method should be used.

The method should never be used for systems at pressures higher than 70 psia or temperatures

outside the range 100 to 900 F. Because the composition effect on K-values is ignored, it can be

expected to yield poor results for mixtures of aromatics with paraffins, naphthenes and olefins.



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Grayson-Streed

This method (GS) is based on the Chao-Seader method and represents an attempt by Grayson and

Streed to extend the Chao-Seader approach to the higher temperatures and pressures encountered

in oil refining. Grayson and Streed also fit special equations for the liquid fugacities of methane

and hydrogen, using data available from hydrocracking operations.

Suitable for the refinery heavyend columns such as crude, vacuum, FCC main fractionators and

coker columns. It can also be used for most refinery gas plant operations and hydrogen processes

such as reforming and hydrocracking. For hydrocracking, more accurate hydrogen solubilities are

predicted by using one of the SRK modifications. General limits are pressures less than 3000 psia

and temperatures less than 800 F, although the method usually extrapolates reasonably well with

temperature.



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Curl-Pitzer method

The Curl-Pitzer method (CP) predicts the enthalpies and entropies for liquids and vapors. The

enthalpy deviation is computed by using the principle of corresponding states, i.e., in terms of the

reduced temperature, reduced pressure and the acentric factor. The critical temperature and

pressure for the mixture are computed using the mixing rules of Stewart, Burkhart and Voo.

The method is limited to nonpolar mixtures and can be used for Pr up to 10.0, Tr for liquids in the

range 0.35 to 4.0, and Tr for vapors in the range 0.6 to 4.0. Curl-Pitzer can be used to predict the

enthalpies and entropies for liquids and vapors.

The enthalpy deviation is computed using the principle of corresponding states, i.e., in terms of

the reduced temperature, reduced pressure and the acentric factor. The critical temperature and

pressure for the mixture is computed using the mixing rules of Stewart, Burkhart and Voo.

Curl-Pitzer is suitable for most hydrocarbon applications including natural gas and refinery

processes. The method must extrapolate for vacuum columns;Lee-Kesler method is

recommended for this application.

For heavyends, the saturated vapor Tr is less than 0.6 and the method must extrapolate.Extrapolation usually produces reasonable results.



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Johnson-Grayson

The Johnson-Grayson method (JG) can be used to predict enthalpies for hydrocarbon liquids and

vapors. It is essentially an ideal enthalpy correlation, using saturated liquid at -200 F as the

datum. Vapor phase corrections are computed with the Curl-Pitzer method. The pressure effects

on the liquid phase are ignored.

The method is useful for heavy hydrocarbons over the temperature range 0 to 1200 F. It can be

extrapolated with reasonable results. This method should not be used for mixtures lighter than

carbon number five.

This method is suitable for refinery heavyend systems such as vacuum systems and synthetic fuel

applications with heavy oils.



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API Liquid Density

The API method (API) can be used to predict liquid densities at flowing conditions. A standard

liquid density is computed at 60 F, using the weight average of the component densities. The

reduced temperature and pressure of the mixture at 60 F and 14.696 psia are computed with the

Kay rule and used to determine a density factor, C, from Figure 6A2.21 in theAPI Technical

Data Book. A second factor is determined at the flowing temperature and pressure for the mixtureand the flowing density is computed from the equation below:

The method is applicable to most hydrocarbon systems, provided that the reduced temperature is

less than 1.0.



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Ideal

The Ideal method obtains liquid densities from pure component liquid density correlations.

This method is suitable for systems of similar components at low pressures and temperatures.



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SIMSCI Databanks

The SIMSCI databanks, SIMSCIand PROCESS, contain more than 1700 components and are

adequate for nearly all flowsheet models.



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User-Defined Petroleum Components

You can define petroleum components by supplying two of the three following properties for

each component:

Normal Boiling Point


Molecular WeightSIM4ME uses internal correlations to estimate the third parameter, when missing.



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Assay

Components derived fr

SIM4ME Thermodynamics

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