Copyright: Copyright © Momentum Software, Inc.


Add New Component
The easiest way to add a new component is to copy a similar component and then change the values that are different.

The constants stored in the database are:

Name:  The component name up to 40 characters (required).

Formula:  The component formula, i.e.  C6H14 (optional).

Mol Wt:  The molecular weight. (required).

Tf:  The normal freezing temperature - deg K (optional).

Tb:  The normal boiling temperature - deg K (optional).

Tc:  The critical temperature - deg K (required).

Pc:  The critical pressure  bars (required).

Vc:  The critical volume  cm3/gmole (required).

Zc:  The critical compressibility factor (required).

Wo:  The acentric factor (required).

Vapor pressure constants A, B, C, D, and E  (required if vapor pressure equations are selected)

     Log10 (P) = A + B/T + C Log10(T) +DT + ET^2;      (P in bars and T in deg K)

     Tmn:  Minimum temperature for the vapor pressure equation (deg K) (optional).

     Tmx:  Maximum temperature for the vapor pressure equation (deg K) (optional).

Liquid Density constants A, B and n  (required if liquid density polynomials are selected)

     Den = A + B^ -(1 - T/Tc)^n;      (Den in g/ml,  T in deg K and Tc Critical Temp deg K)

     Tmn:  Minimum temperature for the liquid density equation (deg K) (optional).

     Tmx:  Maximum temperature for the liquid density equation (deg K) (optional).

Ideal gas heat capacity constants A, B, C, D and E  (required for energy calculations)

     Cp = A + B T + C T^2 + D T^3 + E T^4      (Cp in J/gmole-K and T in deg K)

     Tmn:  Minimum temperature for the heat capacity equation (deg K) (optional).

     Tmx:  Maximum temperature for the heat capacity equation (deg K) (optional).

Liquid heat capacity constants A, B, C and D  (required for liquid polynomial energy calculations)

     Cp = A + B T + C T^2 + D T^3      (Cp in J/gmole-K and T in deg K)

     Tmn:  Minimum temperature for the heat capacity equation (deg K) (optional).

     Tmx:  Maximum temperature for the heat capacity equation (deg K) (optional).

Vapor Viscosity constants A, B and C  (required for vapor viscosity calculations)

     Log10 (n) = A + B T + C T^2      (n in centiPoise and T in deg K)

     Tmn:  Minimum temperature for the viscosity equation (deg K) (optional).

     Tmx:  Maximum temperature for the viscosity equation (deg K) (optional).

Liquid Viscosity constants A, B, C and D  (required for liquid viscosity calculations)

     Log10 (n) = A + B/T + C T + DT^2      (n in centiPoise and T in deg K)

     Tmn:  Minimum temperature for the viscosity equation (deg K) (optional).

     Tmx:  Maximum temperature for the viscosity equation (deg K) (optional).

Vapor Thermal Conductivity constants A, B and C  (required for vapor thermal cond calculations)

     k = A + B T + C T^2      (n in W/m-K and T in deg K)

     Tmn:  Minimum temperature for the thermal cond equation (deg K) (optional).

     Tmx:  Maximum temperature for the thermal cond equation (deg K) (optional).

Liquid Thermal Conductivity constants A, B and C  (required for liquid thermal cond calculations)

     Log10 (k) = A + B (1 - T/C)^2/7      (n in W/m-K and T in deg K)

     Tmn:  Minimum temperature for the thermal cond equation (deg K) (optional).

     Tmx:  Maximum temperature for the thermal cond equation (deg K) (optional).

Liquid Surface Tension constants A and N  (required for surface tension calculations)

     S = A (1 - T/Tc)^N      (S in dynes/cm2, T in deg K and Tc Critical Temp deg K)

     Tmn:  Minimum temperature for the surface tension equation (deg K) (optional).

     Tmx:  Maximum temperature for the surface tension equation (deg K) (optional).


Adiabatic
Select this button to calculate an adiabatic flash.  The outlet enthalpy equals the inlet enthalpy plus the mechanical work term.

You must specify the flash outlet pressure, the temperature and fraction vapor will be calculated.


Adiabatic Flash
Adiabatic Flash Example

Here is an example of an adiabatic flash calculation.  This example uses the keyboard to navigate around the program as much as possible.  Follow along closely because this example will throw you a curve.

1.  Start the FlashCalc program and select the components.

Press Alt+S to display the Common components list

You can use the up and down arrow keys to scroll the list.

Press the Insert key to select the first component in the list, Methane and enter 7 for the molar ratio.

Press the down arrow key until Ethane is at the top of the list.

Press the Insert key to select Ethane and enter 2 for the molar ratio.

Select n-Butane with the mouse cursor and enter 1 for the molar ratio.

2.  Perform the adiabatic flash calculations.

Press (Ctl + the right arrow key) to go to the Flash page

Select the Temp button under INLET CONDITIONS so the program will calculate the temperature.

Enter 1000 for the inlet pressure and 100 for the inlet percent vapor, a saturated vapor at 1000 PSIA.

Select the Adiabatic button on the flash drum to set the type of calculation.

Enter 100 under FLASH CONDITIONS to set the flash let down pressure.

Press the F9 key to perform the calculations.

Note the inlet and outlet temperatures are the same.  This is because the default method of calculation is vapor pressure equations.  When vapor pressure equations are selected as the calculation method the vapor phase is treated as an Ideal Gas and enthalpy is not a function of pressure.  If you drop the pressure from 1000 to 100 PSIA the program will show no temperature change which is incorrect.  Press (Ctl + the right arrow key) (twice) to go to the Options page and note the Equilibrium calculation method.

Select the Soave-Redlich Kwong button under the Equilibrium method.

3.  Perform the adiabatic flash calculations (again).

Press (Ctl + the left arrow key) to go back to the Flash page

Press the F9 key to perform the calculations.

Note the temperature now drops from 30 to -63 deg F.  Also note the inlet temperature changed from 86 deg to 30 deg F.  Vapor pressure equations are only intended for relatively low pressure calculations, i.e. less than 3 atms.  If you press the Page Up or Page Down key you will see the stream properties grid.  Press the Page Up or Page Down key again to return to the flash diagram.

To print the flash results press Ctl+P and select the printer.


Autarchic
Select this button to calculate an autarchic flash.  Autarchic \ô-'tär-kik\ means "independent", the pressure, temperature and vapor fraction of the flash are specified independently of the inlet conditions.


Bubble Points

A mixture bubble point temperature can not be greater than the critical temperature.  However most phase diagrams are drawn as a continuous curve for esthetic purposes.  The FlashCalc program generates the bubble points above the critical temperature on diagrams by constructing a cubic equation which meets the following requirements.  The equation passes through the highest two bubble points below the critical temperature and the highest two dew points below the cricondenbar.  These four requirements are used to calculate the four coefficients of the cubic equation.  This equation is then used to generate the phase diagram between the critical temperature and the cricondenbar.

Mixture dew points can be greater than the mixture critical temperature because the liquid has a different composition.


Calculate Diagram
Select this button or press F9 to calculate the selected diagram.


Calculate Flash
Calculate the flash results.  Select the inlet stream and flash conditions below, Either pressure, temperature or vapor fraction can be calculated.  Select the property to calculate and specify the other two.


Calculation Range
Normally FlashCalc calculates the entire phase diagram, this is the preferred method.  If only a very small portion of the phase envelope is to be displayed on the diagram you may want more points in the displayed range.  You can specify the minimum and maximum pressure in the current pressure units to calculate causing more points to be within the range.

For property diagrams you can set the X axis range either pressure or temperature in the current units.


Common Components List
Select this button to display about 50 of the most commonly encountered compounds in the gas industry.


Common List
Common component list.  To Deselect a component select it again.


Comp Cp Tmn
Minimum temperature deg K for the ideal gas heat capacity equation - (optional)


Comp Cp Tmx
Maximum temperature deg K for the ideal gas heat capacity equation - (optional)


Comp CpA
Ideal gas heat capacity constant:

Cp = A + BT + CT^2 + DT^3 + ET^4

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if energy calculations are required)


Comp CpB
Ideal gas heat capacity constant:

Cp = A + BT + CT^2 + DT^3 + ET^4

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if energy calculations are required)


Comp CpC
Ideal gas heat capacity constant:

Cp = A + BT + CT^2 + DT^3 + ET^4

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if energy calculations are required)


Comp CpD
Ideal gas heat capacity constant:

Cp = A + BT + CT^2 + DT^3 + ET^4

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if energy calculations are required)


Comp CpE
Ideal gas heat capacity constant:

Cp = A + BT + CT^2 + DT^3 + ET^4

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if energy calculations are required)


Comp Formula
Component chemical formula 20 chracters maximum - (optional)


Comp HVA
Heat of Vaporization Constant A:

Hv = A ( 1 - T / Tc) ^ N

Hv: Joules / gmole

Tc: Critical Temperature Deg K

T: Temperature Deg K


Comp HVN
Heat of Vaporization Constant N:

Hv = A ( 1 - T / Tc) ^ N

Hv: Joules / gmole

Tc: Critical Temperature Deg K

T: Temperature Deg K


Comp LCp Tmn
Minimum temperature deg K for the liquid heat capacity equation - (optional)


Comp LCp Tmx
Maximum temperature deg K for the liquid heat capacity equation - (optional)


Comp LCpA
Liquid heat capacity constant:

Cp = A + BT + CT^2 + DT^3

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if the polynomial option is selected for liquid energy calculations)


Comp LCpB
Liquid heat capacity constant:

Cp = A + BT + CT^2 + DT^3

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if the polynomial option is selected for liquid energy calculations)


Comp LCpC
Liquid heat capacity constant:

Cp = A + BT + CT^2 + DT^3

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if the polynomial option is selected for liquid energy calculations)


Comp LCpD
Liquid heat capacity constant:

Cp = A + BT + CT^2 + DT^3

Cp: Joules/gmole-deg K,  T:deg Kelvin

(required if the polynomial option is selected for liquid energy calculations)


Comp LT Tmn
Minimum temperature deg K for the liquid thermal conductivity equation - (optional)


Comp LT Tmx
Maximum temperature deg K for the liquid thermal conductivity equation - (optional)


Comp LTA
Liquid Thermal Conductivity constant:

Log (k) = A + B(1 - T/C)^2/7

Log: Base 10 logarithm,  k: W/m-deg K,  T:deg Kelvin

(required if liquid thermal conductivity calculations are required)


Comp LTB
Liquid Thermal Conductivity constant:

Log (k) = A + B(1 - T/C)^2/7

Log: Base 10 logarithm,  k: W/m-deg K,  T:deg Kelvin

(required if liquid thermal conductivity calculations are required)


Comp LTC
Liquid Thermal Conductivity constant:

Log (k) = A + B(1 - T/C)^2/7

Log: Base 10 logarithm,  k: W/m-deg K,  T:deg Kelvin

(required if liquid thermal conductivity calculations are required)


Comp LV Tmn
Minimum temperature deg K for the liquid viscosity equation - (optional)


Comp LV Tmx
Maximum temperature deg K for the liquid viscosity equation - (optional)


Comp LVA
Liquid Viscosity constant:

Log (Vsc) = A + B/T + CT + DT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if liquid viscosities are calculated)


Comp LVB
Liquid Viscosity constant:

Log (Vsc) = A + B/T + CT + DT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if liquid viscosities are calculated)


Comp LVC
Liquid Viscosity constant:

Log (Vsc) = A + B/T + CT + DT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if liquid viscosities are calculated)


Comp LVD
Liquid Viscosity constant:

Log (Vsc) = A + B/T + CT + DT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if liquid viscosities are calculated)


Comp Ld Tmn
Minimum temperature deg K for the liquid density equation - (optional)


Comp Ld Tmx
Maximum temperature deg K for the liquid density equation - (optional)


Comp LdA
Liquid Density Constant:

Den = A B ^ -(1 - T/Tc)^n

T: deg Kelvin, Tc: Critical Temp deg Kelvin

(required if polynomials are used for liquid density calculations)


Comp LdB
Liquid Density Constant:

Den = A B ^ -(1 - T/Tc)^n

T: deg Kelvin, Tc: Critical Temp deg Kelvin

(required if polynomials are used for liquid density calculations)


Comp LdN
Liquid Density Constant:

Den = A B ^ -(1 - T/Tc)^n

T: deg Kelvin, Tc: Critical Temp deg Kelvin

(required if polynomials are used for liquid density calculations)


Comp Liq HC
If there are two liquid phases select this button if the liquid is soluable in the hydrocarbon phase - (required)


Comp Liq Water
If there are two liquid phases select this button if the liquid is soluable in the water phase - (required)


Comp Mol Wt
Component molecular weight - (required)


Comp Name
Component name, 40 characters maximum - (required)


Comp Pc
Component critical pressure in bars - (required)


Comp ST Tmn
Minimum temperature deg K for the surface tension equation - (optional)


Comp ST Tmx
Maximum temperature deg K for the surface tension equation - (optional)


Comp STA
Liquid Surface Tension constant:

S = A (1 - T/Tc)^N

S: dynes/cm2,  T: deg Kelvin,  Tc: Critical Temp deg K

(required if surface tension calculations are required)


Comp STN
Liquid Surface Tension constant:

S = A (1 - T/Tc)^N

S: dynes/cm2,  T: deg Kelvin,  Tc: Critical Temp deg K

(required if surface tension calculations are required)


Comp Tb
Component normal boiling temperature deg K - (optional)


Comp Tc
Component critical temperature deg K - (required)


Comp Tf
Component freezing temperature deg K - (optional)


Comp VT Tmn
Minimum temperature deg K for the vapor thermal conductivity equation - (optional)


Comp VT Tmx
Maximum temperature deg K for the vapor thermal conductivity equation - (optional)


Comp VTA
Vapor Thermal Conductivity constant:

k = A + BT + CT^2

k: W/m-deg K,  T:deg Kelvin

(required if vapor thermal conductivity calculations are required)


Comp VTB
Vapor Thermal Conductivity constant:

k = A + BT + CT^2

k: W/m-deg K,  T:deg Kelvin

(required if vapor thermal conductivity calculations are required)


Comp VTC
Vapor Thermal Conductivity constant:

k = A + BT + CT^2

k: W/m-deg K,  T:deg Kelvin

(required if vapor thermal conductivity calculations are required)


Comp VV Tmn
Minimum temperature deg K for the vapor viscosity equation - (optional)


Comp VV Tmx
Maximum temperature deg K for the vapor viscosity equation - (optional)


Comp VVA
Vapor Viscosity constant:

Log (Vsc) = A + BT + CT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if vapor viscosities are calculated)


Comp VVB
Vapor Viscosity constant:

Log (Vsc) = A + BT + CT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if vapor viscosities are calculated)


Comp VVC
Vapor Viscosity constant:

Log (Vsc) = A + BT + CT^2

Log: Base 10 logarithm,  Vsc: Centipoise,  T:deg Kelvin

(required if vapor viscosities are calculated)


Comp Vc
Component critical volume cc/gmole - (either Vc or Zc is required)


Comp Vp Tmn
Minimum temperature deg K for the vapor pressure equation - (optional)


Comp Vp Tmx
Maximum temperature deg K for the vapor pressure equation - (optional)


Comp VpA
Constant for the vapor pressure equation (required if vapor pressure equations are to be used).

Log (P) = A + B/T + C Log (T) + DT + E T^2

Log: Base 10 logarithm, P: Bars, T: deg Kelvin


Comp VpB
Constant for the vapor pressure equation (required if vapor pressure equations are to be used).

Log (P) = A + B/T + C Log (T) + DT + E T^2

Log: Base 10 logarithm, P: Bars, T: deg Kelvin


Comp VpC
Constant for the vapor pressure equation (required if vapor pressure equations are to be used).

Log (P) = A + B/T + C Log (T) + DT + E T^2

Log: Base 10 logarithm, P: Bars, T: deg Kelvin


Comp VpD
Constant for the vapor pressure equation (required if vapor pressure equations are to be used).

Log (P) = A + B/T + C Log (T) + DT + E T^2

Log: Base 10 logarithm, P: Bars, T: deg Kelvin


Comp VpE
Constant for the vapor pressure equation (required if vapor pressure equations are to be used).

Log (P) = A + B/T + C Log (T) + DT + E T^2

Log: Base 10 logarithm, P: Bars, T: deg Kelvin


Comp Wo
Component acentric factor - (required)

The acentric factor is the base 10 log of the reduced vapor pressure, at a reduced temperature of 0.7, minus one.


Comp Zc
Component critical compressibility factor - (either Vc or Zc is required)


Company Logo
Printing Your Company Logo

Your company logo can be printed on FlashCalc output sheets.  The logo must be a Windows bitmap file named LOGO.BMP and must be in the same folder as the FlashCalc program, FlashCalc.exe.  By default this is "C:\Program Files\Momentum\FlashCalc".  If the default folder was not used when the program was installed you can use the Windows find program to locate the file FlashCalc.exe.

In this folder is a Windows bitmap file named LOGO.BMP.  You can change or replace this file with your company's logo.  The new bitmap can be any dimensions but always prints 300 dots per inch regardless of printer resolution.  So to make your logo one inch wide and 1/2 inch high it should be 300 pixels wide and 150 pixels high.  The color format can be monochrome, 16 colors or 256 colors and should have a white background.  The bitmap can not contain more that 256 colors because high color bitmaps do not have color tables.  A color table is required to build a mask so the background color (white) is transparent.

Remember to save your bitmap file in the same folder as FlashCalc.exe and it must be named LOGO.BMP.

If you do not want to print a logo delete the file LOGO.BMP from folder "C:\Program Files\Momentum\FlashCalc".


Complete Component List
Select this button to display the complete component list of over 1500 compounds.


Complete List
Complete component list.  To Deselect a component select it again.


Components Page


Composition Decimal Places
Select the desired composition decimal places, 0 through 9.


Contents
FlashCalc Help Contents

Introduction

Getting Started

Adiabatic Flash Example

Copying a Phase Diagram Example

Using the Program

End User License Agreement

Registering FlashCalc


Copy Diagram
Select this button to copy the diagram.  You can then paste the diagram picture or the data points into other applications.


Copy Flash
Copy the flash results.  Below you can select whether the flash diagram and or the stream results are to be copied.  After copying the results you can paste them into other applications as a graphic picture or as text.


Copy Landscape
Copy the data in landscape orientation.


Copy Picture
This option copies the data to the Windows clipboard in picture format, (metafile).


Copy Portrait
Copy the data in portrait orientation.


Copy Text
This option copies the data to the Windows clipboard in text format, (tab delimited).


Copying a Phase Diagram

Here is an example of creating a phase diagram and copying it to another application.  This example uses the keyboard to navigate around the program as much as possible.

1.  Start the FlashCalc program and select the components.

Press the Alt+S keys to display the Common components list

Press the down arrow key until Methane is at the top of the list.

Press the Insert key to select Methane and enter 7 for the molar ratio.

Press the down arrow key until Ethane is at the top of the list.

Press the Insert key to select Ethane and enter 2 for the molar ratio.

Press the down arrow key until n-Butane is at the top of the list.

Press the Insert key to select n-Butane and enter 1 for the molar ratio.

2.  Select the equation of state.

Press (Ctl + the left arrow key) to go to the Options page and select the Peng-Robinson equation.

3.  Draw the Phase Diagram.

Press (Ctl + the left arrow key) to go to the Diagrams page and press F9 to draw the diagram.  Note the default diagram is a pressure - temperature (phase) diagram.  You can select other types of diagrams from the list box on the left side of the window.  You must press F9 or select the Calculate button after changing the type of diagram to recalculate the points.

4.  Set the Diagram Options.

Select the Diagram Options button at the bottom left of the window.  In the Dialog Options window set all the colors to white except the background, make it black and select the transparent button.

To set a diagram item color first select the item to be set such as "Title Color" and then select one of the colored boxes below.

5.  Copy the diagram.

Select the OK button to close the Options window and return to the diagram.  Press Ctl+C to copy the diagram to the Windows clipboard.  The program will ask if you want to copy a picture of the diagram or the data points in text format.  Select Copy Picture and the select the Copy button.

6.  Paste the diagram into another application.

Select the other application that is to receive the diagram.  Check the application instructions it probably says to select the Edit - Paste Special menu to paste the picture into the application.


Decimal Places Composition
Select the desired composition decimal places, 0 through 9.


Decimal Places Density
Select the desired density decimal places, 0 through 9.


Decimal Places Energy
Select the desired energy decimal places, 0 through 9.


Decimal Places Heat Capacity
Select the desired heat capacity decimal places, 0 through 9.


Decimal Places Percent Vapor
Select the desired percent vapor decimal places, 0 through 9.


Decimal Places Pressure
Select the desired temperature decimal places, 0 through 9.


Decimal Places Temperature
Select the desired temperature decimal places, 0 through 9.


Decimal Places Volume
Select the desired volume decimal places, 0 through 9.


Density Decimal Places
Select the desired density decimal places, 0 through 9.


Density Units
Select the desired input and output density units.


Diagram Axis Color
Select this button and then select the axis color from the boxes below.


Diagram Axis Labels Color
Select this button and then select the axis labels color from the boxes below.


Diagram Background Color
Select this button and then select the background color from the boxes below.


Diagram Color
Select this box to set the color of the diagram item selected above.


Diagram Constant
This is the diagram constant pressure or temperature.


Diagram Constant Pressure
Select this button to draw a constant pressure, property vs temperature diagram.


Diagram Constant Temperature
Select this button to draw a constant temperature, property vs pressure diagram.


Diagram Data Line Color
Select this button and then select the data line color from the boxes below.


Diagram Data Points Color
Select this button and then select the data points color from the boxes below.


Diagram Major Grid Line Color
Select this button and then select the major grid line color from the boxes below.


Diagram Maximum Display X
This is the maximum X axis value to display on the diagram.  This is the same as selecting a display rectangle with the mouse.


Diagram Maximum Display Y
This is the maximum Y axis value to display on the diagram.  This is the same as selecting a display rectangle with the mouse.


Diagram Maximum X
This is the maximum value to calculate.  For a property diagram this is the maximum temperature or pressure in the current units.  For a phase diagram this is the maximum pressure in the current pressure units.


Diagram Minimum Display X
This is the minimum X axis value to display on the diagram.  This is the same as selecting a display rectangle with the mouse.


Diagram Minimum Display Y
This is the minimum Y axis value to display on the diagram.  This is the same as selecting a display rectangle with the mouse.


Diagram Minimum X
This is the minimum value to calculate.  For a property diagram this is the minimum temperature or pressure in the current units.  For a phase diagram this is the minimum pressure in the current pressure units.


Diagram Minor Grid Line Color
Select this button and then select the minor grid line color from the boxes below.


Diagram Options
Select this button to change the diagram options such as color and range.


Diagram Options Close
Close the Diagram Options Window.


Diagram Range
Calculate the entire phase diagram.  This is the recommended method for phase diagrams.  However you may want to specify a range for property diagrams if the desired range is not calculated.


Diagram Title Color
Select this button and then select the diagram title color from the boxes below.


Diagram Transparent Background
Select this box to draw the diagram with a transparent background.  This is useful when printing or copying the diagram and you want the existing background to show through.


Diagram Type
Select the type of diagram.  For diagrams other than a P-T phase diagram enter the constant pressure or temperature below.


Diagram X Increment
This is the horizontal axis major grid line increment value if automatic scaling is not selected.


Diagram X Scale
If this box is checked the program will automatically select the horizontal (X) diagram axis scale.  If it is not checked you can enter your own scale.  You can also set the diagram scale by selected the desired rectangle on the diagram using the mouse.


Diagram Y Increment
This is the vertical axis major grid line increment value if automatic scaling is not selected.


Diagram Y Scale
If this box is checked the program will automatically select the vertical (Y) diagram axis scale.  If it is not checked you can enter your own scale.  You can also set the diagram scale by selected the desired rectangle on the diagram using the mouse.


Diagrams
The type of diagram is selected in the list box to the left.  Press Ctrl+P to print the diagram or Ctrl+C to copy the diagram to the Windows clipboard.  After you copy the diagram you can then paste it into other applications.

The Pressure-Temperature phase diagram displays the "hydrocarbon" bubble and dew points.  To obtain the water dew points use the Water Saturate procedure on the Components tab.

You can zoom in on a diagram by selecting one corner of the desired area and pressing and holding the left mouse button.  Then drag the rectangle to the desired area and release the left mouse button.


Diagrams Page


Draw Axis Tick Marks
Diagram axis tick marks will be drawn if this box is checked.


Draw Bubble Points
Bubble points above the critical temperature will be drawn if this box is checked, see help topic Bubble Points.


Draw Composition
The composition will be printed at the bottom of the diagram if this box is checked.


Draw Critical Point
The critical point will be drawn on the diagram if this box is checked.


Draw Major Grid Lines
Diagram major grid lines will be drawn if this box is checked.


Draw Minor Grid Lines
Diagram minor grid lines will be drawn if this box is checked.


Draw Point Markers
Diagram point markers will be drawn if this box is checked.


Draw VP Equations
Vapor pressure equations are typically more accurate than cubic equations of state for low pressure bubble point calculations.  Select this box to use vapor pressure equations for bubble point calculations.  Otherwise the selected equation of state will be used for all calculations.


Dry Basis
Flash stream component mole and weight percents are on a dry bases.  The water flow is moles or weight per 100 moles or weight of the dry stream.  The total is 100 plus the water.


Edit Diagram Points
Press this button to edit the diagram points.  This option is not intended to produce false or misleading data.  Instead it is intended to be used to correct one or two bad points near the critical region.  All equations of state lose accuracy near the critical point.

It is usually easier to edit points if you zoom in first.  To zoom in merely use the left mouse button to drag a rectangle around the desired area.  To correct a bad point:

1.  Select the 'Edit Points' button to start the edit mode.

2.  Select the desired point with the mouse cursor and press and hold the left mouse button.

3.  Drag the point to the desired location and release the mouse button.

4.  Repeat steps 2 and 3 for each point to be moved.

5.  Select the 'Edit Points' button again to exit the edit mode.

If you recalculate the diagram all changes will be lost.


Edit Diagram Titles
Press this button to change the diagram titles and axis labels.  If you recalculate the diagram the changes will be over written.


Edit Flash Titles
Edit the flash results titles.  The titles are printed and copied at the top of the flash results sheet.  The titles are rewritten each time the flash is calculated.


Edit Points
Select this button to edit the diagram points.  First select this button to start editing.  Select the points one at a time and drag them to the desired location.  Then select this button again to exit the editing mode.  This option is used to correct points very near the critical point where equations of state are sometimes inaccurate.


Edit Titles
Select this button to edit the diagram titles and axis labels.  The titles are rewritten if you recalculate the diagram.


End User License
License Agreement

IMPORTANT - PLEASE READ CAREFULLY:  This Momentum Engineering Software, Inc. End User License Agreement ("EULA") is a legal agreement between you (either an individual or a single entity) and Momentum Engineering Software, Inc. ("MOMENTUM") for the software product identified above, which includes computer software and may include associated media, printed materials, and "online" or electronic documentation ("SOFTWARE PRODUCT"). By installing, copying, or otherwise using the software, you are agreeing to be bound by the terms of this EULA.  If you do not agree to the terms of this EULA, promptly return the unused software to MOMENTUM and your money will be refunded.

Information contained in this software product has been obtained by Momentum Engineering Software, Inc. ("MOMENTUM") from sources believed to be reliable.  However, MOMENTUM does not guarantee the accuracy or completeness of any information contained in this product and MOMENTUM is not responsible for any errors, omissions or damage arising out of the use of this product.  This product is licensed with the understanding that MOMENTUM is supplying information but is not attempting to render engineering or other professional services.  If such services are required, the assistance of an appropriate professional should be sought.

The SOFTWARE PRODUCT is licensed, not sold.

1.	GRANT OF LICENSE.  This EULA grants you the following rights:

Applications Software Use and Storage - You may install and use one copy of the SOFTWARE PRODUCT.  The primary user of the computer on which the SOFTWARE PRODUCT is installed may also install a second copy on a portable computer for his or her exclusive use.   The SOFTWARE PRODUCT should not be in use on both computers at the same time by different users.  You may also make a copy of the software on a portable diskette for backup purposes.

2.	DESCRIPTION OF OTHER RIGHTS AND LIMITATIONS.

Limitations on Reverse Engineering, Decompilation, and Diasassembly.  The SOFTWARE PRODUCT contains copyrighted material, trade secrets, and other proprietary material, and in order to protect them you may not decompile, reverse engineer, or disassemble  the SOFTWARE PRODUCT.

Software Transfer.  You may transfer all of your rights under this EULA and all of the components of the SOFTWARE PRODUCT  to another user, provided you retain no copies, and provided the other party reads and accepts terms and conditions of this EULA.

Resale.  You may not resell, or otherwise transfer for value, the SOFTWARE PRODUCT.

Rental.  You may not rent, lease, or lend the SOFTWARE PRODUCT.

Copyright.  The SOFTWARE PRODUCT is protected by copyright laws and international copyright treaties, as well as other intellectual property laws and treaties.   Therefore, you may not copy or reprint any portion of the SOFTWARE PRODUCT except as described in this EULA or without written consent of MOMENTUM.

Termination.  Without prejudice to any other rights, MOMENTUM may terminate this EULA if you fail to comply with the terms and conditions of this EULA.  In such event, you must destroy the SOFTWARE PRODUCT. You may terminate this EULA at any time by destroying the SOFTWARE PRODUCT.

Export Law Assurances.  You agree that the SOFTWARE PRODUCT nor any other data related to MOMENTUM will be exported outside the United States except as authorized and as permitted by the laws and regulations of the United States

Limited Warranty.  MOMENTUM warrants that the SOFTWARE PRODUCT will perform substantially in accordance with the accompanying written materials for a period of ninety (90) days from the date if receipt.

Waiver of Implied Warranties.  As a material part of the consideration for this Agreement, you agree that you are taking the software "as is" with any and all latent and patent defects and that there is no warranty by MOMENTUM that the software is fit for a particular purpose.  You acknowledge that you are not relying upon any representation, statement or other assertion outside of the Agreement with respect to the performance, characteristics, quality or condition of the software, but are relying upon your investigation and use of the software. You are taking the software under the express understanding there are no express or implied warranties (except for the limited warranties set forth in the above paragraph).

Limited Liability.  In no event will MOMENTUM, or it's directors, officers, or employees be liable to you for any special, consequential, incidental, or indirect damages whatsoever (including, without limitation, damages for loss of business profits, business interruption, loss of business information, or any other pecuniary loss) arising out of the use or inability to use this software, even if MOMENTUM has been advised of the possibility of such damages.  The parties agree that the actual damages and consequential damages that might be sustained by you as a result of use of this software in accordance with this Agreement are uncertain and would be difficult to ascertain, and that the sum of Fifty and 00/100 Dollars ($50.00) would be reasonable compensation for any such damages. MOMENTUM hereby promises to pay, and you hereby agree to accept, such sum as liquidated damages, and not as a penalty, in the event of any such damages.  The provisions of this section shall apply if loss or damage, irrespective of cause or origin, results directly or indirectly to persons or property, from performance or nonperformance of the obligations imposed by this contract, or from negligence, active or otherwise.


Energy Decimal Places
Select the desired energy decimal places, 0 through 9.


Energy Units
Select the desired input and output energy units.


Entropy Liquid
Select the liquid entropy calculation method.


Entropy Vapor
Select the vapor entropy calculation method.  An equation of state is the recommended method.


Find Begins
Select this button if the name or formula begins with the search string


Find Contains
Select this button if the name or formula contains the search string


Find Formula
Select this button to search for a component formula


Find Name
Select this button to search for a component name


Find Select
Select this button to select the first visible component in the list


Find String
Enter the component name or formula to search for


Flash Diagram
Display the flash diagram.  Select the Properties button to display the stream properties.  Use the page-up or page-down buttons to toggle between the pages.


Flash Diagram Page
On the Flash Diagram page you can specify the inlet stream and flash conditions.  Either pressure, temperature or vapor fraction can be calculated.  Select the one to calculate and specify the other two.


Flash Fraction Vapor
Select this button to calculate the flash fraction vapor.  You must specify the pressure and temperature.  The fraction vapor is on a dry basis.


Flash Fraction Vapor 1
Select this button to calculate the flash fraction vapor.  You must specify the pressure and temperature.


Flash Page


Flash Pressure
Select this button to calculate the flash pressure.  You must specify the temperature and the fraction vapor.


Flash Pressure 1
Select this button to calculate the flash pressure.  You must specify the temperature and the fraction vapor.


Flash Properties
Display the flash stream properties.  Select the Diagram button to display the flash diagram.


Flash Properties Page
The flash properties page displays the stream properties from the flash calculations.


Flash Temperature
Select this button to calculate the flash temperature.  You must specify the pressure and the fraction vapor.


Flash Temperature 1
Select this button to calculate the flash temperature.  You must specify the pressure and the fraction vapor.


Getting Started

The FlashCalc program is designed to be easy to use, that's enough training, let's create something.  How about a vapor pressure diagram for water.

Step 1.

The first step is to select the components.  The components tab should be visible, if not select it with the mouse.  Select the 'Common List' button. Scroll the component library, (list box on the left), down and locate "Water" and select it with the left mouse button.  Note the component name "Water" appears in the selected components window on the right.  You do not need to enter the molar ratio if there is only one component the program will guess the mole fraction is one.

Step 2.

Now select the Diagrams tab at the top of the window or enter Alt+D from the keyboard to switch to the Diagrams tab.  To calculate the vapor pressure select the Calculate button or press F9 on the keyboard and violà, we have a Water Vapor Pressure Diagram.

Step 3.

Pretty good, but the diagram pressure range is over 3000 PSIA, this is because by default the maximum pressure is the critical pressure for pure compounds.  What if we only want the vapor pressure up to 500 PSIA?  OK.  Select the diagram using the left mouse button and drag the rectangle to the desired range, (while holding the left mouse button down).

Step 4.

Still not quite right because we are interested in low pressures.  Select the 'Diagram Options' button and then the Calculation Range tab.

Uncheck the box marked 'Calculate entire diagram' and enter the values 0 and 20 these are the minimum and maximum pressures in the current units (PSIA).  Select the OK button on the options dialog box and then press F9 to recalculate the diagram.

Step 5.

To print the diagram select the Print button, enter Ctrl+P or use the menu option File, Print Diagram... then select the desired printer and then select the print button.

You just created your first FlashCalc diagram.

Next I recommend you learn to navigate around the program using the keyboard.  Using the keyboard can save time over selecting items with the mouse especially on a laptop computer, see - Special Keys.


Heat Flow
The heat flow (Q) is displayed on the flash diagram page and is represented by a dashed line.  A positive number indicates the addition of heat to the system, (heating), a negative number indicates the removal of heat from the system, (cooling).

If the flash stream flow units are mole or mass fractions the Q value is on a mole or unit mass bases, (BTU/Lb, Cal/kg, etc.).  If the flash stream flow units are moles or mass per unit time the Q value is total energy per unit time, (BTU, Cal, etc.).


Hydrocarbon Components List
Select this button to display hydrocarbon compounds, compounds containing only carbon and hydrogen.


Hydrocarbons List
Hydrocarbon components list.  To Deselect a component select it again.


Inlet Fraction Vapor
Select this button to calculate the inlet fraction vapor.  You must specify the pressure and temperature.  The fraction vapor is on a dry basis.


Inlet Fraction Vapor 1
Select this button to calculate the inlet fraction vapor.  You must specify the pressure and temperature.


Inlet Pressure
Select this button to calculate the inlet pressure.  You must specify the temperature and the fraction vapor.


Inlet Pressure 1
Select this button to calculate the inlet pressure.  You must specify the temperature and the fraction vapor.


Inlet Temperature
Select this button to calculate the inlet temperature.  You must specify the pressure and the fraction vapor.


Inlet Temperature 1
Select this button to calculate the inlet temperature.  You must specify the pressure and the fraction vapor.


Inorganics Component List
Select this button to display inorganic compounds.


Inorganics List
Inorganics component list.  To Deselect a component select it again.


Interaction Parameters
Select this button to enter interaction parameters for the SRK and PR equations of state.  The program can automatically look up parameters for common components.


Introduction
The FlashCalc program performs single and multi component flash calculations and physical property estimation using rigorous calculation methods.  The program can calculate vapor-liquid equilibrium using four different methods:

1.  Vapor Pressure Equations

2.  Redlich-Kwong Equation of State

3.  Soave-Redlich-Kwong Equation of State

4.  Peng-Robinson Equation of State

Propriatory convergence procedures give the maximum possible reliability and range.  Once the pressure, temperature and phase compositions have been calculated the program can calculate density, specific volume, enthalpy, entropy, heat capacity, viscosity, thermal conductivity for both liquid and vapor phases and liquid surface tension.

The component property data are from sources believed to be reliable and check calculations have been performed by Momentum Engineering Software, Inc.  However Momentum Engineering Software, Inc. can not guarantee the accuracy or completeness of the data contained in this program."

Momentum Engineering Software, Inc. assumes no obligation or liability resulting from the use of this program.  No warranty, expressed or implied, is given

Momentum Engineering Software, Inc.

P.O. Box 570

Lake Jackson, TX  77566

Visit our web site at www.momentumware.com

Copyright 1998-2000  Momentum Engineering Software, Inc.  All rights reserved.


Isentropic
Select this button to calculate an isentropic flash.  The outlet entropy is the same as the inlet entropy.

You must specify the flash outlet pressure, the temperature and fraction vapor will be calculated.


Isobaric
Select this button to calculate an isobaric flash.  The pressure is the same as the inlet pressure.  You can calculate either the temperature or the fraction vapor.


Isothermal
Select this button to calculate an isothermal flash.  The temperature is the same as the inlet temperature.  You can calculate either the pressure or the fraction vapor.


K Value Limits
Limits must be placed on vapor liquid equilibrium constants, 'K values'.  This is because when a very small number is added to a very large number the small number has little or no significance.  This is especially true when working with components that have a large boiling range.  The recommended values are 1.0E-09 and 1.0E+09 but you can use smaller values, 1.0E-03, 1.0E+03 for difficult to converge cases.


Library
The component library is used to select the components in a specified mixture..  To include a component in the mixture merely select it with the left mouse button.  To remove a component from the mixture select it again.  The components can be sorted by selecting the header buttons at the top of the list.  Selecting a header button once sorts the components by that field in ascending order.  Selecting the header button again sorts in descending order.


Liquid Density
Select the liquid volume and density calculation method.  A polynomial equation is the recommended method.


Liquid Enthalpy
Select the liquid enthalpy and heat capacity calculation method.


Liquid Entropy
Select the liquid entropy calculation method.


Liquid Entropy Method
Select the liquid entropy calculation method.


Liquid Heat Capacity
Select the liquid enthalpy and heat capacity calculation method.


Liquid Specific Heat
Select the liquid enthalpy and heat capacity calculation method.


Liquid Volume
Select the liquid volume and density calculation method.  A polynomial equation is the recommended method.


Maximum K Value
This is the maximum K value to be used in VLE calculations.


Maximum X
This is the maximum horizontal axis value if automatic scaling is not selected.


Maximum Y
This is the maximum vertical axis value if automatic scaling is not selected.


Menu
The menu is used to select different options, such as opening and saving files, printing, copying data and accessing help.


Message Sound
When FlashCalc displays a message box it also plays a sound, 'Ding".  To suppress the sound uncheck the Play Message Sound box.


Minimum K Value
This is the minimum K value to be used in VLE calculations.


Molar Flow Rates
Display the components in the flash stream grid as molar flow rates.  If the volume units are British the flows are Lbmoles per unit time, if the volume units are metric the flows are Kgmoles per unit time.

The total flow is specified on the Components tab under the selected components.


Mole Percents
Display the components in the flash stream grid as mole percents.


Normalize
Normalize inlet molar ratios to mole percents.  This does not affect the total moles which is independent of the molar ratios.  This is optional the molar ratios do not need to sum to one.


Options Diagram
Select this button to change the diagram options such as color and range.


Options Page


Options Tab
The Options Tab displays different options available to calculate equilibrium, mixture properties.  It also lets you select units, decimal places, diagram characteristics and colors.


Peneloux Correction Factor
If the SRK equation is used to calculate the liquid volume and density and this box is checked, a Peneloux correction factor will be applied to the liquid volume and density.  A polynomial equation is the recommended method.


Peng Robinson
The Peng Robinson equation of state is used to calculate equilibrium temperature and pressure and vapor and liquid properties.  This or the Soave Redlich Kwong equation are the recommended methods for high pressure hydrocarbon mixtures.


Percent Vapor Decimal Places
Select the desired percent vapor decimal places, 0 through 9.


Phase Diagrams

The FlashCalc program correctly draws most phase diagrams, but no program can guarantee it will work in every case.  If a phase diagram does not draw correctly some of the things you can do are:

On the Diagram Options window select the "Use VP Eqns for Bubble Pt" box.  This will cause FlashCalc to use vapor pressure equations to calculate the bubble point curve.  The dew point curve will still be calculated using the selected equation of state.  Only the pressure and temperature are calculated using the vapor pressure all other physical properties use the selected equation of state.

Change the maximum diagram pressure.  If the maximum pressure is set to "max" the program estimates the cricondenbar pressure.  You can specify a lower maximum pressure.  This will cause the increment between the points to be smaller and the calculations will become more stable.

Change the calculation method.  In some cases the Soave-Redlich-Kwong equation works better than the Peng-Robinson equation and vice versa.  The most stable method is Vapor Pressure equations because the equilibrium K values are not a function of composition.

If only one or two points are incorrect you can use the "Edit Points" option to correct the diagram, see Edit Points.

The points on the diagram are hydrocarbon bubble and dew points.  To obtain water dew points use the Water Saturate procedure on the Components tab.


Pressure Decimal Places
Select the desired pressure decimal places, 0 through 9.


Pressure Properties
This is the pressure of the calculated properties.  The units are specified under the options tab.


Pressure Units
Select the desired input and output pressure units.


Print Copies
Select the number of copies to print.


Print Copies 1
Select the number of copies to print.


Print Copies 2
Select the number of copies to print.


Print Diagram
Select this button to print the selected diagram.  Before printing you can change the diagram options by selecting the button at the bottom marked "Diagram Options".


Print Flash
Select this button to print the flash results.  Both the flash diagram and the stream results will be printed.


Print Landscape
Print the output in landscape orientation.


Print Portrait
Print the output in portrait orientation.


Printer Comment
This is a comment associated with the selected printer.


Printer Location
This is the selected printer location.


Printer Status
This is the current status of the selected printer.


Printer Type
This is the selected printer type.


Redlich Kwong
The Redlich Kwong equation of state is used to calculate equilibrium temperature and pressure and vapor and liquid properties.  This method is not recommended for most cases.


Registered
The registered user name and company name are set when the program is installed and can not be changed without reinstalling the program.


Registered User Company Name
The registered user name and company are set when the program is installed and can not be changed without reinstalling the program.


Registered User Name
The registered user name is set when the program is installed and can not be changed without reinstalling the program.


Registering FlashCalc
Registering FlashCalc:

Before you can select components and run your own cases you must register this copy of FlashCalc.  This reduces software piracy and allows us to sell you software at a lower cost.  When you register your copy of FlashCalc Momentum Engineering Software will provide you with an activation code.

In the FlashCalc program select the menu option Help/About FlashCalc, then select the Register button to display the serial number and enter the activation code.

To register your copy of FlashCalc in the US and Canada call 1-877-256-7645 or outside the US and Canada call 1-979-239-1315.

You will need the serial number and a VISA or MasterCard number.  The cost is $495 US.  Texas residents add 8.25% sales tax.

If you get a recording leave your phone number and an Email address and we will send you an activation code.


SRK Parameters

FlashCalc uses the Graboski and Daubert (1978) modification of the Soave Redlich Kwong equation of state.  The original equation used the parameter:

a^0.5 = 1 + (1 - Tr^0.5)(0.480 + 1.574 w - 0.176 w^2)

Graboski and Daubert proposed the term:

a^0.5 = 1 + (1 - Tr^0.5)(0.48508 + 1.55171 w - 0.15613 w^2)

and for Hydrogen:

a^0.5 = 1.096 exp (-0.15114 Tr)


Select Printer
Select the desired printer for output.


Selected Component Number
Select this button to return the components to the original order they were selected.


Selected Components
The selected components list shows the components in the mixture.  The maximum number of components is 32.  The molar ratios can be any mole based amounts, they need not sum to one or the total.

The Total Moles is required only if mole or weight flows is selected for the flash streams, (see Options tab).  If the volume units are British the total moles are Lbmoles per unit time, if the volume units are metric the total moles are Kgmoles per unit time.

The total moles can be entered independently from the molar ratios, but if you click on "Total Moles" FlashCalc will sum the molar ratios for you.


Set Inlet
Select this button to use the vapor or liquid stream from the previous flash as the inlet for the next flash.


Set X Ordinate
This list box specifies either the X or Y ordinate property.  The ordinate X or Y is controlled by pressing the Transpose X and Y button.


Set Y Ordinate
This list box specifies either the X or Y ordinate property.  The ordinate X or Y is controlled by pressing the Transpose X and Y button.


Soave Redlich Kwong
The Soave Redlich Kwong equation of state is used to calculate equilibrium temperature and pressure and vapor and liquid properties.  This or the Peng Robinson equation are the recommended methods for high pressure hydrocarbon mixtures.


Sort Selected Compnents by Molar Ratio
The Molar Ratio button sorts the selected components by molar ratios.  Selecting this button once sorts in descending order, selecting the button again sorts in ascending order.


Sort Selected Components by Name
The Components button sorts the selected components by name.  Selecting this button once sorts in ascending order, selecting the button again sorts in descending order.


Sort Selected Components by Number
Display selected components in the order they were selected.


Sort by Component Formula
Sort the component list by component formula.


Sort by Component Name
Sort the component list by component name.


Sort by Component Number
Sort the component list by component number.


Sort by Mol Wgt
Sort the component list by molecular weight.


Sort by Omega
Sort the component list by Acentric Factor (omega).


Sort by Pc
Sort the component list by Critical Pressure


Sort by Tc
Sort the component list by Critical Temperature


Sort by Zc
Sort the component list by Critical Compressibility Factor.


Special Keys

You can use the following special keys to navigate around the program and to perform specific functions.  Note some keys perform different functions depending on which page is visible.  You select the visible page using the tabs marked Components, Flash, Diagrams and Options.

Calculate - F9:

If the Flash page is displayed the flash calculations are started.

If the Diagrams page is displayed the diagram is calculated.

Copy - Ctl+C:

Copies the currently selected page, Components, Flash or Diagram,  to the clipboard.  You can then paste the data into other applications.

Exit - Alt+F4:

Press Alt + F4 to exit the program.

Find - Ctl+F:

Switches to the Components page and opens the find component dialog box.

Help - F1 or Shift F1:

F1 displays the program help topics.  To display context help for a particular control press Shift F1 and the select the control.

New Case - Ctl+N:

Press Ctl + N to begin a new case (file).

Open - Ctl+O:

Press Ctl + O to open an existing file.

Page Up / Page Down:

If the Flash page is displayed these keys toggle between the flash diagram and stream properties grid.

Print - Ctl+P:

Prints the currently selected page, Components, Flash or Diagram.

Save - Ctl+S:

Press Ctl + S to save the current file.

Scroll - Up and Down Arrows:

If the Components page is displayed you can scroll the components list using the up and down arrow keys.  The press the insert key to select the top visible component in the list.  If the Diagrams page is displayed you can scroll the selected diagram list box using the up and down arrow keys.

Select Components - Insert:

If the Components page is displayed you can select the component displayed at the top of the list by pressing the Insert key.  If the component is already selected it is deselected.

Switching Pages - Alt+C, Alt+A, Alt+D, Alt+O:

You can use these keys to switch between the main pages, Components (Alt+C), Flash (Alt+A), Diagrams (Alt+D) and Options (Alt+O).  You can also use Ctl + the left or right arrow keys to switch pages.

Switching Pages - (Alt or Ctl) + Left or Right Arrows:

You can use (Alt or Ctl) + the left or right arrow keys to switch between the main pages.

Tab - Enter:

You can use the Enter key as a tab key to move to the next input field.  Hold the shift key down and press Enter to move to the previous input field.

Window Size - F3 or F12:

You toggle the FlashCalc window from normal size to full screen and back by pressing the F3 or F12 keys.


Step Size
FlashCalc calculates intermediate points between the points displayed on the diagram.  The calculation step size is the distance between the intermediate points.  At the minimum step size setting 18 intermediate points are calculated for every diagram point and at the maximum step size there is 1 intermediate point for every point displayed.

The step size must be set so the change in composition from one point to the next is small enough for convergence.  However a step size too small can cause extraneous points near the critical region.

The recommended setting is about in the middle.  If your diagram is not a smooth curve try decreasing the step size.  If there are extraneous points try increasing the step size.


Surface Tension
The pure component surface tensions are calculated using an empirical equation:

S = A B^N

The surface tension for liquid mixtures is calculated using the Sprow-Prausnitz method.

Sprow, F.B., Prausnitz, J.M.; Trans. Faraday Soc., 62: 1105, (1966).


Tab Controls
The four tab controls access different sections of the program.  The Components section selects the components in the mixture.  The Flash section performs flash equilibrium calculations and generates stream properties.  The Diagrams section displays mixture diagrams and the Options sections allows you select different program options.


Technical Support

Momentum Engineering Software offers five avenues of technical support:

1.   On the Momentum Engineering Software Internet site www.momentumware.com there are answers to frequently asked questions.

2.   You can submit your questions by email to  help@mesi.com  If you submit your questions before noon Central time we will try to reply by the end of the day.  If you submit your questions after noon we will reply by noon the next business day.

3.   You can fax your questions to:  979-285-9412

4.   You can mail questions to:

Momentum Engineering Software, Inc.

P.O. Box 570

Lake Jackson, TX  77566

5.   You can call  979-239-1315  from 9 am to 3 pm Central time Monday through Friday.


Temperature Decimal Places
Select the desired temperature decimal places, 0 through 9.


Temperature Units
Select the desired input and output temperature units.


Thermal Conductivity
The pure component thermal conductivities are calculated using empirical equations:

For Gases:

k = A + BT + CT^2

The thermal conductivity for gas mixtures is calculated using the Mason and Saxena modification to the Wassiljewa method.

Mason, E.A. and Saxena, S.C.; Phys. Fluids, 1:316, (1958).

For Liquids:

log k = A + B (1 - T/C)^2/7

The thermal conductivity for liquid mixtures is calculated using the Li method.

Li, C.C.; AIChE J, 22: 927, (1976).


Tool Tips
When you hold the mouse cursor over a control text appears describing the control, this is called a tool tip.  The program will only display tool tips if this box is checked.


Total Moles
The total moles are specified below the selected components on the Components page.  This is the total flow in the flash inlet stream.  Total moles are required only if molar or weight flow is selected for the flash stream flows on the Options page.

If British volume units are selected the moles are Lbmoles per unit time, if metric volume units are selected the moles are Kgmoles per unit time.

Total moles can be specified independently from the molar ratios, but if you click on "Total Moles" FlashCalc will sum the molar ratios for you.

The inlet stream total flow is specified in moles even though the output is weight percents or weight flows.

If weight flows and British volume units are selected the weight output is Lbs per unit time, if metric volume units are selected the output is Kgs per unit time.


Transpose Diagram
Select this button to transpose the X and Y axis of the diagram.  The diagram will also be printed and copied transposed.


Transpose X and Y
Press this button to transpose, (switch), the diagram X and Y axis.  You can also press Alt+T


Using the Program

The Physical Properties program contains four pages, Components, Flash, Diagrams and Options.  You can change pages by selecting the tabs at the top of the window or by pressing the, Alt+C, Alt+A, Alt+D or Alt+O keys.  Each page performs a specific function:

The Components Page:

The Components page allows you to select components and specify the composition.  There are four lists; the Complete List displays the entire component library and contains over 1500 compounds, the Common List conatins about 50 of the most commonly encountered components in the gas industry, the Hydrocarbon List contains compounds containing only carbon and hydrogen and the Inorganics List contains non hydrocarbon compounds.  You can select components from any list.  You can sort the lists by, number, name, formula, molecular weight, or any other header button, by selecting the header buttons at the top of the list.  The first time you select a header button the list is sorted in ascending order, select the same button again to sort in descending order.  You can scroll the lists to the right to view the critical temperature - deg K, the critical pressure - bars, the critical compressibility factor and the acentric factor (omega).

To select a component place the mouse cursor on the desired component and press the left mouse button.  The component name will appear in the Selected Components list on the right.  Continue until all of the desired components have been selected, the maximum number is 32.  The Selected Components list also contains the composition in molar ratios.  The molar ratios can be mole fractions, mole percents, total moles, etc.  They do not need sum to 1.  If you only select one component you do not need to specify the composition.

To deselect a component, select the component name in the library again and it will be removed from the Selected Components List.

To search for a component select the menu option Library | Find Component or press the Ctrl+F keys.  You can search the component names or formulas and set the search string for begins with or contains.  The library list will scroll up and down as you enter the search string.  To select the top component in the list press the Alt+S keys.

To print the selected components and their properties select the menu option, File | Print Components or press the Ctrl+P keys while the Components page is displayed.  This list can be copied to the Windows clipboard by selecting the menu option, Edit | Copy Components... or by pressing the Ctrl+C keys while the Components page is displayed.  Then you can then paste the list into other Windows applications.

To enter the molar ratios of the compounds select the number to the right of the first compound on the Selected Compounds by clicking on the number with the mouse.  Then enter that component’s molar ratio and then tab to move to the next component’s molar ratio.  You can also use the enter key as a tab key.  Any molar ratio can be individually selected with the mouse. The molar ratios do not have to sum to 1 or 100, however, they can be normalized to 100% using the Normalize button if you desire.

User Defined Components can also be added to the library by two different methods:

Method 1, Add new component from scratch:  Select New Component under the Library menu.  Then begin typing in data into the properties form.  See Add New Component under the HELP/TOPICS menu to get a description of the input data required.

Method 2, Copy and edit an existing component:  This method could be used when a compound is similar to one in the database but a few of the properties need to be changed.  Using this method, only one component can be selected.   Therefore, components to be added should be done prior to starting a case, i.e. you cannot have 5 components selected and then decide you want to copy a component in the database, the program would not know which component to copy.

These user defined components are stored in a separate database, USER.DAT, so they will not be lost when the user upgrades to a new version of the program.

Editing And Deleting Components

Similar to using Method 2 above, only one component can be selected so both of these operations should be done prior to starting a case.  These operations are under the Library menu.  You can only change components you have added.  If you want to change the properties of a component in the library, first copy it and then change the copy.

The Flash Page:

The Flash page performs equilibrium flash calculations for the components and compositions specified on the Components page.  Two of the three stream extrinsic properties (temperature, pressure and percent vapor) must be entered under the INLET CONDITIONS on the left side of the screen.  Check the radio button next to the parameter to be calculated.  Then the type of calculation is selected using the radio buttons inside the flash tank in the center of the screen:

autarchic = independent of the inlet conditions

isothermal = constant temperature

isobaric = constant pressure

adiabatic = constant enthalpy

1)	Any parameter calculated by the program will be inactive, i.e. if isothermal is chosen, then the temperature is automatically set equal to the inlet conditions temperature.

2)	Check the radio button on the parameter to be calculated.

3)	Set the remaining parameters to the desired values.  (Two parameters are set for the autarchic case; one parameter is set for isothermal and isobaric cases; for the adiabatic case, the pressure must be set and the temperature and % vapor will be calculated.)

After the conditions are set, select the Calculate button or press F9 to calculate and display the results. The program calculates the density, specific volume, enthalpy, entropy, heat capacity, and critical properties for the inlet stream and both liquid and vapor streams.  These values can be viewed by clicking the Properties button.

Compression Calculations:  Note that the downstream conditions do not have to be at a lower pressure than the inlet.  In such cases the flash is calculating the inlet and outlet conditions of a compressor, blower, or pump.  Select the button of the property to be calculated and specify the other two.  Select the Calculate button or press the F9 key to perform the flash calculations.  The method used to calculate the equilibrium K values is specified on the Options page.

Dew points and Bubble points  If the INLET CONDITIONS are set to a vapor percentage of 0 or 100 and the temperature or pressure to be calculated, the resulting inlet stream will be saturated, i.e. a 0% vapor will be a liquid at its bubble point, and a 100% vapor will be a gas at its Dew points

Copy and Pasting  These commands are found throughout the program and apply to the active workspace, (the visible page).  For instance, the Print button on the Flash tab will print a drawing of the flash tank with the Inlet and Flash Conditions, while on the Diagram tab it will print the graph currently being displayed.  Selecting the Copy button will copy the flash results so they can be pasted into another application.  The Copy button also has the option of copying the current picture (flash tank or graph) or the actual data.  These can then be pasted into other applications such as a drawing program or a spreadsheet using the Paste command in the target application.

The Properties Data Sheet Title is set when the Calculate button is selected.  If there is only one component selected the title is set to "Component Name  Properties Data Sheet", if there is more than one component selected, the title is set to "Physical Properties Data Sheet" and the composition is printed on bottom of the data sheet.  The second line of the data sheet title specifies the method used for the calculations, Vapor Pressure Equations, Redlich-Kwong EOS, Soave-Redlich-Kwong EOS or Peng-Robinson EOS, (Equation Of State).

You can change the Property Data Sheet Titles by selecting the Edit Property Titles button.  However, if you select the Calculate button to recalculate the data sheet the titles will be rewritten.

To print the Properties Data Sheet select the menu option, File | Print Properties or press the Ctrl+P keys while the Properties page is displayed.  The Properties Data Sheet can be copied to the Windows clipboard by selecting the menu option, Edit | Copy Properties or by pressing the Ctrl+C keys while the Properties page is displayed.  You can then paste the properties into other Windows applications.

The Diagrams Page:

The Diagrams page creates equilibrium property diagrams.  The type of diagram is specified in the two list boxes in the upper left corner of the page.  The X ordinate is the diagram horizontal axis and the Y ordinate is the diagram vertical axis.  The ordinate the list boxes refers to is controlled by the Transpose Axes button.  Select the Calculate button or press the F9 key to create the diagram.

The diagram Maximum Pressure defaults to the critical pressure for pure compounds and twice the true critical pressure for mixtures.  Nearly all mixtures will encounter a cricondenbar below this pressure.  The cricondenbar is the maximum pressure at which two phases can exist.  You can set the diagram minimum and maximum pressures by entering them in the currently selected pressure units.  The minimum pressure is 0.10 bars, (1.5 PSIA).

The Diagram Title is set when the Calculate button is selected.  If there is only one component selected the title is set to "Component Name  Phase Diagram"  or "Component Name Property Name", if there is more than one component selected, the title is set to "Phase Diagram" or "Saturated - Property Name"  and the composition is printed on the diagram.  The second line of the diagram title specifies the method used for the calculations, Vapor Pressure Equations, Redlich-Kwong EOS, Soave-Redlich-Kwong EOS or Peng-Robinson EOS, (Equation Of State).

You can change the Diagram Titles by selecting the Edit Diagram Titles button.  However, if you select the Calculate button to recalculate the diagram the titles will be rewritten.

Editing Diagram Points  Select the Edit Points button to edit the diagram points.  First select this button to start editing.  Select the points one at a time and drag them to the desired location.  Then select this button again to exit the editing mode.  This option is used to correct points very near the critical point where equations of state are sometimes inaccurate.  It is not the intent of this option to produce misleading data.

Diagram options can be specified by selecting the Diagram Options button.  You can specify the colors and which items are drawn.  These options apply not only to the screen display but also to printed and copied diagrams.

To print the Diagram select the menu option, File | Print Diagram... or press the Ctrl+P keys while the Diagrams page is displayed.  The diagram can be copied to the Windows clipboard by selecting the menu option, Edit | Copy Diagram or by pressing the Ctrl+C keys while the Diagrams page is displayed.  You can then paste the diagram into other Windows applications.

The Pressure-Temperature phase diagram displays the "hydrocarbon" bubble and dew points.  To obtain the water dew point use the Water Saturate procedure on the Components tab.

The Options Page:

The Options page allows you to specify; units, decimal places, calculation methods, interaction parameters (kij),  and diagram colors and options.

Use the lists on the left side of the Options Page to select the desired units for temperature, pressure, volume, density and energy.  The energy and temperature units are combined to set the units for enthalpy and heat capacity, i.e.  BTU/lb-deg F.

You can also specify the number of decimal places properties are displayed and printed.

Under Equilibrium you can specify how the equilibrium K values are calculated:

Vapor Pressure Equations are recommended for pure components and non-hydrocarbon mixtures.

The Redlich Kwong Equation of state is generally not considered as accurate as the Soave or Peng Robinson equations.

The Soave Redlich Kwong and Peng Robinson Equations of state are recommended for hydrocarbon mixtures especially at high pressures.

You can specify how the liquid and vapor volumes and densities are calculated.  For the vapor you can choose either the currently selected equation of state or an ideal gas.  For the liquid volume and density you can use either the currently selected equation of state or the Rackett equation.  If vapor pressure equations are selected for equilibrium the Rackett equation will be used for liquid volume and density.

By selecting the check box you can apply the Peneloux correction factor to the liquid volume and density.  This option only applies if the Soave equation is selected as the equilibrium method.  The Peneloux factor is intended to improve the accuracy of the liquid volume and density predicted by the Soave Redlich Kwong equation of state.

You can specify how the liquid and vapor enthalpies are calculated.  For the vapor you can choose either the currently selected equation of state or an ideal gas.  For the liquid enthalpy you can use either the currently selected equation of state or the Sternling Brown equation.  If vapor pressure equations are selected for equilibrium the Sternling Brown equation will be used for liquid enthalpy.

You can specify how the liquid and vapor entropies are calculated.  For the vapor you can choose either the currently selected equation of state or an ideal gas.  For the liquid entropy you can use either the currently selected equation of state or the Sternling Brown equation.  If vapor pressure equations are selected for equilibrium the Sternling Brown equation will be used for liquid enthalpy.

For equilibrium calculation method one of two methods can be selected.  When performing equilibrium calculations two loops are used.  Typically the outer loop solves for the phase compositions and the inner loop solves for the intrinsic property, (pressure, temperature or fraction vapor).  This is calculation method one and is the recommended method.  If you select calculation method two the intrinsic property is solved for in the outer loop and the phase compositions are solved in the inner loop.

Tool tips can be turned on or off by selecting the check box marked Display Tool Tips.  Tool tips are small text boxes that appear when the mouse cursor is held over a control, (button, edit field or check box).


VLE Calculation Method 1
When solving equilibrium problems two loops must be converged.  One loop solves for the phase compositions while the other solves for temperature, pressure or fraction vapor.  Typically the composition loop is the outer loop, this is calculation method 1 and is the recommended method for most cases.  If you choose calculation method 2 the composition loop is the inner loop.  This allows the program to solve cases involving wide boiling mixtures and cases very close to the critical point, which previously would not converge to a solution.


VLE Calculation Method 2
When solving equilibrium problems two loops must be converged.  One loop solves for the phase compositions while the other solves for temperature, pressure or fraction vapor.  Typically the composition loop is the outer loop, this is calculation method 1 and is the recommended method for most cases.  If you choose calculation method 2 the composition loop is the inner loop.  This allows the program to solve cases involving wide boiling mixtures and cases very close to the critical point, which previously would not converge to a solution.


Vapor Density
Select the vapor volume and density calculation method.  An equation of state is the recommended method.


Vapor Enthalpy
Select the vapor enthalpy and heat capacity calculation method.  An equation of state is the recommended method.


Vapor Entropy
Select the vapor entropy calculation method.  An equation of state is the recommended method.


Vapor Heat Capacity
Select the vapor enthalpy and heat capacity calculation method.  An equation of state is the recommended method.


Vapor Pressure Equations
Use vapor pressure equations to calculate equilibrium temperature and pressure.  An ideal gas is assumed for vapor properties.  Liquid properties can not be calculated using this method.  This is the recommended method for non hydrocarbon and wide boiling mixtures.  This method is usually quite accurate for low pressures, less than 50 PSIA.  This method can be used for single components at all pressures but should not be used for mixtures at high pressures.


Vapor Volume
Select the vapor volume and density calculation method.  An equation of state is the recommended method.


Viscosity
The pure component viscosities are calculated using empirical equations:

For Gases:

k = A + BT + CT^2

The viscosity for gas mixtures is calculated using the Wilke method.

Wilke, C.R.; J. Chem. Phys.,18: 517, (1950).

For Liquids:

log k = A + B/T + CT + DT^2

The viscosity for liquid mixtures is calculated using the Teja and Rice method.

Teja, A.S. and Rice, P.; Chem. Eng. Sci., 36: 7 (1981).


Volume Decimal Places
Select the desired volume decimal places, 0 through 9.


Volume Units
Select the desired input and output volume units.


Water Dew Point
The phase diagram displays hydrocarbon bubble and dew points.  To obtain a water dew point use the Water Saturate procedure on the Components tab.


Water Phase
This box should be checked if water and hydrocarbons are selected for a case and FlashCalc will check for a liquid water phase.  If this box is not checked the water is assumed to be miscible in the liquid hydrocarbon phase.


Water Saturate
FlashCalc offers several methods to calculate the saturated water content of gas streams, the selected equilibrium method (VP, RK, SRK, PR) and a correlation developed by Momentum Engineering Software for natural gas.

The natural gas correlation is based on data from "Gas Purification", Arthur Kohl and Fred Riesenfeld.  The correlated range is (40 to 300 deg F), (14.7 to 10,000 PSIA), (4 - 149 deg C), (1 - 680 atms).

The default temperature and pressure are taken from the inlet stream on the Flash page.  If British volume units are selected the water content is displayed in pounds of water per million standard cubic feet (Lbs/MMSCF), standard conditions are 60 deg F and 14.7 PSIA.  If metric volume units are selected the water content is displayed in kilograms of water per million standard cubic meters (Kgs/MMSCM), standard conditions are 20 deg C and 1 atm.

At low pressure, less than 3 atms (44 PSIA), all methods yield similar results.  At higher pressures use either an equation of state or the natural gas correlation.  If the gas is mostly methane the natural gas correlation is recommended otherwise use an equation of state such as SRK or PR.

Acid gases containing CO2 or H2S contain more water vapor than normally predicted.  This is commonly believed to be caused by a vapor phase hydration of the CO2 and H2S.  The FlashCalc program does not correct for this phenomenon.  If water content is critical you should check an acid gas treating reference.


Weight Flow Rates
Display the components in the flash stream grid as mass flow rates.  If the volume units are British the flows are Lbs per unit time, if the volume units are metric the flows are Kgs per unit time.

The total flow is specified on the Components tab under the selected components.  The input flow is specified in moles even though the output is on a weight bases.


Weight Percents
Display the components in the flash stream grid as weight percents.


Wet Basis
Flash stream component mole and weight percents are on a wet bases.  The mole or weight percents total to 100 even though the water may be in a separate phase.


X Ordinate
This list box specifies either the X or Y ordinate property.  The ordinate X or Y is controlled by pressing the Transpose X and Y button.


Y Ordinate
This list box specifies either the X or Y ordinate property.  The ordinate X or Y is controlled by pressing the Transpose X and Y button.


Zoom Diagram
You can zoom in on a diagram by selecting one corner of the desired area and pressing and holding the left mouse button.  Then drag the rectangle to the desired area and release the left mouse button.  Merely click on the diagram (without dragging) to return to the original diagram limits.