There can be few other mathematical models in any branch of engineering which are so well suited to computer solution and that have prompted the development of so many truly different algorithms. Since the late 1950s, hardly a year has gone by without the publication of at least one (and usually more than one) new algorithm. The evolution of algorithms for solving the MESH equations has been influenced by, among many other things, the availability (or lack) of sufficient computer storage and power. Not so very long ago a distillation column simulation had to be performed on a mainframe or mini computer. However, the remarkable increase in the capabilities of personal computers throughout the 1980s has meant that distillation columns often can be more effectively simulated on such machines.
Our own interest in computer simulation in general and of distillation in particular is due in part to the fact that we find distillation calculations quite fascinating. We are involved with students who need to simulate distillation operations either as part of a course on separation processes or as part of a large scale design project that all students must do in their final year of study. In the past these design studies were performed with simulation systems that were installed on a mainframe computer.
In our view, much of the software capable of solving distillation problems that existed when we were planning ChemSep was not suitable for use in the first undergraduate course that deals with stagewise separation processes. For one thing, the comprehensive flowsheeting packages of the time lacked interfaces that were as easy to use and as flexible as we thought they could be. In addition, very few such programs could be run on the kinds of computers that students might possess. Finally, most such programs were not available at prices low enough for students to acquire their own copy.
With these (and other) thoughts in mind Arno Haket and ourselves began the ChemSep project in February 1988 at the University of Technology in Delft (TU Delft) in The Netherlands. Version 0.92 of ChemSep was first introduced to graduate and undergraduate level students at Delft in September 1988 by Professor Hans Wesselingh of the TU Delft (he moved to the RijksUniversiteit Groningen in The Netherlands). The use of ChemSep by Professor Hans in the courses he taught was of enormous value to us in improving the programs.
As a result of the success enjoyed by the program during those first courses at Delft, we continued to develop ChemSep. A series of improved versions (numbered 1.0 to 1.5) was developed by Arno Haket and Harry Kooijman in Delft and Ross Taylor in Potsdam, New York. This development would have been difficult if it were not for the international computer networks that allowed us to hold intercontinental computerised conversations. Many pages of electronic mail testify to our progress (and lack of progress) over the last few years. We find it interesting to look back on our mail and discover the things that we argued about so long ago in our efforts to make things "just right".
In March 1991 we began writing ChemSep 2.0. This version is a completely new set of programs and data files with many new and improved features. Version 2.0 was first used in courses at the University of Amsterdam and at Clarkson University in Potsdam, New York in September 1991.
Some of the features of ChemSep include:
ChemSep 2.0 is the result of too many hours of coding, testing and recoding. It consists of several executable files plus a number of small data files for recording various bits and pieces of information. The driver and interface are written in Borland Pascal (version 7.0) and involve over 50,000 lines of code. The flash and column simulation programs are written in standard Fortran 77. The source code is also over 50,000 lines in length. The code has been developed on mostly PC's with the help of the Multi-Edit programmers editor and WATCOM F77 and F77/386 compilers (versions 10.5). The source code for the column and flash calculations has also been succesfully compiled (unchanged) and executed on a VAX 11/750 and on Sun Workstations. Several of the executable files have been compressed using a public domain utility called LZEXE written by Fabrice Bellard of France. We try to improve the ChemSep software as time permits. We welcome your suggestions for new features and improvements and will try to incorporate as many of your ideas as possible.
Our thanks above all to Professor Hans and to Peter Verheijen who contributed in many ways. Our thanks also to our friends and colleagues at universities in The Netherlands and in the USA who have used earlier versions of ChemSep in their courses or who have tested the program for us. Last, but not least, our thanks to the many students on both sides of the Atlantic Ocean that were forced to use this program or risk failing one of their required courses.
Ross Taylor and Harry Kooijman, 1998
WATCOM F-77 and F-77/386 are products of WATCOM Inc. Borland Pascal is a product of Borland International Inc. Multi-Edit is a product of American Cybernetics.
ChemSep User's Guide
This User's Guide was initially prepared using Word Perfect 5.1 (Word Perfect Corp.) and is now translated to HTML for viewing "online" in a web browser. Key strokes are printed in italics, F5 for example. Bold Face words are used to indicate key words or phrases. With few exceptions, bold face words represent topics that are described elsewhere in the User's Guide. Bold face words often represent words displayed on screen by the ChemSep interface. The name of our software is printed in bold face and italic!
The authors would like to extend their thanks to Sharon Sweeney for reading this document. Any remaining typographical and grammatical errors are, of course, hers!
ChemSep User's Guide
The opening screen identifies the name of program in large bright letters that can be seen from a great distance. We made the opening screen look like this so that anyone who can see your computer screen will know exactly what program you are about to run. The screen lets you know our names and which version of ChemSep you are using. Any limits on the size of problem you can solve with this version of the software are displayed here as well.
Now, do what it says at the bottom of the opening screen and press Any key. Don't worry if your keyboard does not have an Any key, just press some other key instead (but not the Shift, Alt or Ctrl keys) to see the following (extremely boring) screen.
In fact, what you see above the line with the ChemSep v3.60 label is ChemSep's Main menu which is fully described in Chapter 4. At the bottom of the screen is the F-key bar listing the uses of some of the F-keys (as many of them are listed here as we could squeeze in). The F-keys, along with other keyboard assignments, are described in Chapter 3.
cs deproptyped at the system prompt would cause ChemSep to execute and to display the opening screen shown above. However, when Any key was pressed, ChemSep would immediately load the file DEPROP.SEP. If the file contained a solved problem, ChemSep would immediately jump to the Results menu.
There are two command line switches that ChemSep recognizes. Although none of them is necessary to developing a mastery over the program, you may find them useful on occasion.
/k causes ChemSep to execute a Macro that follows. For example:
cs deprop /kisf
jumps to the feed spreadsheet after the startup screen has been
cleared.
/o causes ChemSep to start with a specific configuration (CNF) file. For example:
cs /oset2.cnf
causes ChemSep to load its configuration from the file SET2.CNF.
Notethatyoumustnotuseanyspaces between the switch and the character
string that follows it. In place of the / character used to identify
the switch, you may use - or char '134. For example, the following
three command lines are all equivalent:
cs deprop /kisf cs deprop -kisf cs deprop \kisfThe latter was added to keep unix fans happy.
ChemSep User's Guide
With these seven keys you can go anywhere in the ChemSep interface. Other keys that perform special functions include:
Each menu item has one of its letters highlighted. Pressing that letter will execute the corresponding option. In the illustration above, pressing I while in the main menu would result in the screen image shown. Also, one option in the menu will be under the cursor. When the cursor is on the option you wish to select, press Enter. The arrow keys, as well as Home and End, move the cursor according to the following rules:
The Return option is part of ChemSep's autopilot that will take you through the next option in a predefined sequence. In many cases, the Return option acts in much the same way as Escape except that the cursor may be located in a different place. In the above screen, for example, Escape would clear the specifications menu and leave the cursor on the specifications option in the input menu. The Return option will also go back to the input menu but the cursor will be located one line down on the solve option because that is the next option in the input sequence. In some submenus the Return option may jump to a different branch of the menu tree. Pressing R (or locating the cursor on Return and pressing Enter) will exercise the Return option.
There are a few subtle differences between menus and lists that must be explained. Lists may be distinguished from menus by the lack of highlighted letters. Also, it is possible that not all of the list will fit in the window. It should always be obvious if the list cannot be contained in the displayed window because the word More will appear at the bottom right corner and/or in the top right corner of the list box. The following keys are useful in lists:
This particular spreadsheet serves to illustrate the various features
of ChemSep's spreadsheets. Numerical or character data is entered in
fields. In the spreadsheet shown above the data entry fields are those
in the right hand column. Usually, there will be a label to the left
of the data entry field that identifies or explains the entry to its
right. Some spreadsheets have more than one column of data entry
fields. The feed spreadsheet has a number of columns equal to the
number of feeds.
Many ChemSep spreadsheets have action fields in a line at the bottom
of the spreadsheet. In this example we may Insert a second feed (this
would result in an additional column being inserted in the
spreadsheet, Delete the feed we already have (not a good idea here) or
Return to the previous screen. To exercise these actions place the
cursor on the relevant field and press Enter.
Some of ChemSep's spreadsheet fields require you to press
Enter to bring up a list of options from which you must select
one. The State field is of this kind.
Many of ChemSep's spreadsheets have semi-active fields. That is, a
particular field may not be available in all cases. The three fields
adjacent to the labels Pressure, Vapour fraction and Temperature are
semi-active fields. Only two of these fields are active at any time,
which two depends on the field State.
The following keys are used to move around a spreadsheet:
It may sometimes be more convenient to change an existing data entry.
With the cursor on the relevant field, press Enter to get into
Edit mode. An asterisk (*) in a spreadsheet field indicates an Unset
parameter. With the cursor on a spreadsheet field displaying a *,
press Enter to display the default value and Enter
again to accept it.
In addition to the alpha-numeric keys, the following keys can be used
in a spreadsheet data entry field:
Here are some examples of numerical formula entry:
Formula entry can be useful in the feed spreadsheet where you are
asked to enter the component flows. Perhaps you know the total flow
rate and the mole fractions rather than the component flows. Instead
of using your calculator to compute the component flows, you can let
ChemSep do the calculations for you. By way of an example consider a
column with a feed flow of 573 mol/s containing 36.5 mole percent
ethanol, the rest being water. The component feed flows of ethanol and
water could be typed in as:
ChemSep recognizes the standard prefixes for multiples of 10. For
example:
A numerical formula and a unit string can be entered in the same field
at the same time. All results of formula and unit entry are displayed
in the default set of units.
Notice the prompt box with the invitation to type in the file mask. A
default response, *.SEP, is already available. Pressing Enter
after the prompt for a file mask or by entering wild cards (* and ?)
in the file name prompt box followed by Enter will bring up a
directory of all files meeting the desired file specification. For
example: Typing L*.sep and pressing Enter will bring
up a list of all files with the .SEP extension beginning with the
letter L. Entering *.* after the prompt for a file mask will
bring up a directory of ALL files in the current directory. If
the default response is accepted you will see a screen that looks
something like this:
Pressing any key with a letter or number will make the cursor jump to
the next file or directory whose name begins with that letter. If no
match has been found by the end of the list the search begins again
from the top of the directory list. When you have the name of the data
file you wish to Load, Save, View,or Edit under the cursor, press
Enter.
Rarely are the entire contents of a Table or file displayed in a
single view window. The following keys are useful in a view window:
ChemSep User's Guide
Press Escape to clear any Help message. A second press of F1 while the
help window is displayed brings up the index to the Help system.
The Help system is extensively cross-referenced. Many help messages
and the help index contain one or more words printed in inverse video.
These are keywords and you may use the arrow keys to place the cursor
over one of these keywords. Press Enter to display a new help message
that relates to the highlighted keyword.
F2 displays the last help message shown on screen. ChemSep
remembers the last 16 help pages shown and repeated pressing of
F2 will cause one of the last sixteen help messages to be dislayed
in turn.
A prompt box appears below the Load option asking you for the name of
the file to load. The prompt box contains the default file mask,
*.SEP. SEP is the default extension used by ChemSep for all problem
files. Press Enter to bring up a Directory list of all files
with the extension SEP.
If you know the name of the file you wish to load, type it in the
prompt box. The default file mask will disappear and the file name
being typed will appear in its place. When you have typed in the
complete name including the file extension, press Enter to
load it. If the file has no extension you must end the file name with
a period (.). Consult the section on the Directory facility of ChemSep
for more information on using directory lists to select the file you
wish to load.
The only difference between F4 and the Save option of the File
menu is that Save always prompts you for a file name (mask). F4 only
asks for a file name if no name has been entered. With F4 the prompt
box will appear on the screen close to the last location of the
cursor. Also, when the file has been saved, the cursor will return to
screen location it had prior to the press of F4.
In the left hand column is the name of the quantity whose units you
can set. To the right is the currently selected unit. To change a
currently selected unit use the cursor control keys to move to the
unit you wish to change. Press Enter to display a list of
alternative units that ChemSep recognizes. Use the cursor keys (or
first letters) and Enter to choose the new unit. All
quantities that require this unit will be displayed in the newly
selected unit until you change it again. Selected units are saved in
ChemSep files so the currently selected units may be changed when you
load another file.
Let us illustrate with a specific example. Below is the screen image
of the stream summary table for the Depropanizer example discussed in
Chapter 9 of this User's Guide. In the original problem statement
flows were specified in mol/s, temperatures in Celcius, pressures in
bar, and Enthalpy in kJ/kmol.
To change the Flow Units, press F5 to bring up the Units
spreadsheet. Move the cursor to Flow and press Enter. A list
of alternative units will appear, from whcih we select lbmol/s. In a
similar way change the temperature units to degrees F, the pressure
units to psia, and the enthalpy units to Btu/lbmol. Press
Escape to clear the Units spreadsheet and display the stream
summary in the new set of units. Here is the same stream summary table
in the new set of units:
Press Enter to bring up a Directory list of all files in the
current directory. If you know the name of the file you wish to view,
type it in the prompt box. The default file mask will disappear and
the file name being typed will appear in its place. When you have
typed in the complete name including the file extension, press Enter
to View it. If the file you wish to view has no extension you must end
the file name with a period (.). Consult the section on the Directory
facility of ChemSep for more information on using directory lists to
select the file you wish to view. Press Escape to clear the view
window. The cursor will return to the same location prior to the press
of F7.
The last item in the list are the solve options which are assigned
default values. These are set in the option file which was loaded at
the start of ChemSep (they are saved for each sep-file though!). Here
is an example of a summary screen after the components have been
selected. This particular screen image was obtained while setting up
the Depropanizer illustrative example from Section 10 of this User's
Guide.
Notice the list of components is shown but the other main entries,
Operation, Properties, and Specifications, remain empty. The problem
has also been given a name, TEST.SEP, as indicated on the file name
line.
All the keys available to a View window may be used in a Summary
screen to scroll, Edit, or print the contents of the window. In fact,
it is now necessary to scroll this View window in order to see what
items remain unspecified. The complete summary can be printed and, at
this point in the Input, is reproduced below. Notice the asterisks (*)
that indicate an unspecified item. Also, the Condenser and Reboiler
items remain unspecified. The complete summary specification for this
example is provided in Section 10.
Each macro consists of a sequence of highlighted letters, special
symbols, and key codes. The letters are the ones highlighted in each
menu item. Do not use spaces when entering a new sequence of
characters. You may include Escape and Enter, using
the special symbols shown below. When you have completed the string
press Enter. The new key assignments can be made available
every time you run ChemSep by saving the setup in the "Save options"
item of the Options menu.
The main menu has the following branches:
The file menu contains the following items:
The first four items of the Input menu are concerned with entering
data:
The three items are:
In this case the Results menu is a list of the kinds of Tables that
ChemSep can display for flash problems.
The items in this branch of the main menu are:
ChemSep User's Guide
The File menu can be reached from anywhere in ChemSep using either
F10, F or with
<> .
<> The File menu contains the following items:
A prompt box appears below the Load option asking you for the name of
the file to load. The prompt box contains the default file mask,
*.SEP. SEP is the default extension used by ChemSep for all problem
files. Press Enter to bring up a Directory list of all files
with the extension SEP.
If you know the name of the file you wish to load, type it in the
prompt box. The default file mask will disappear and the file name
being typed will appear in its place. When you have typed in the
complete name including the file extension, press Enter to
Load it. If the file has no extension you must end the file name with
a period (.) otherwise the default extenision, .SEP, is appended.
Consult Directory facility for more information
on using directory lists. F3 jumps directly to the Load option
of the File menu from anywhere in the interface (unless defined
differently under macro's).
The prompt box contains the default file name, NewFile. Type in a new
file name and press Enter if you don't want to use the default
name. All files are given the extension SEP unless you type in a
period (.) followed by an alternative extension. If any existing Input
had been changed but not saved you will be asked if you wish to save
the old Input before the data is reset and the results cleared.
The prompt box contains the default file mask, *.SEP. SEP is the
default extension used by ChemSep for all problem files. Press
Enter to bring up a Directory list of all files with the extension
SEP. Use the cursor control keys to locate the cursor on the name you
wish to use. Press Enter to overwrite the existing file with
the new data. You will be asked to confirm that you wish to overwrite
an old file.
If you don't wish to overwrite an old file simply type a new name in
the prompt box. The default file mask will disappear and the file name
being typed will appear in its place. When you have typed in the
complete name including the file extension, press Enter to
Save it. The file will be given the extension SEP unless you end the
file name with a period (.). Consult Directory
facility for more information on using directory lists.
F4 can also be used to Save the current Input data in a file.
F4 can be pressed anywhere in the interface. Pressing
F4 will result in the immediate overwriting of your file. If no
file name has been given you will be asked to provide one in a prompt
box similar to the one shown above. The only difference is that the
prompt box will appear on the screen close to the last location of the
cursor. Also, when the file has been saved, the cursor will return to
the same location prior to the press of F4.
The prompt box contains the current directory name terminated by char
'134*. Press Enter to bring up a Directory list of directories
on your disk. Use the cursor keys to walk around the directory tree on
your disk. Press Enter when the cursor is over the name of the
directory to which you wish to move. If you know the name of the
directory to which you wish to move, type it in the prompt box. The
default directory name will disappear and the directory name being
typed will appear in its place. When you have typed in the complete
name press Enter to change to that directory. Consult Directory facility for more information on using
directory lists.
If you know the name of the file you wish to view, type it in the
prompt box. The default file mask will disappear and the file name
being typed will appear in its place. When you have typed in the
complete name including the file extension, press Enter to View it. If
the file you wish to view has no extension you must end the file name
with a period (.). Consult the section on View
Windows for further details of how to move around.
F7 can also be used to View a file. F7 can be pressed
anywhere in the interface. Pressing F7 will result in the
display of a prompt box similar to the one shown above. The only
difference is that the prompt box will appear on the screen close to
the last location of the cursor. Also, when the view window has been
cleared (by pressing Escape), the cursor will return to the
same location prior to the press of F7.
If you know the name of the file you wish to edit, you may type it in
the prompt box. The default file mask will disappear and the file name
being typed will appear in its place. When you have typed in the
complete name including the file extension, press Enter to Edit it. If
the file you wish to view has no extension you must end the file name
with a period (.). Consult the section on Edit
Windows for further details of how to move around in and edit a
file displayed in an Edit Window.
If you know the name of the file you wish to copy, type it in the
prompt box. The default file mask will disappear and the file name
being typed will appear in its place. When you have typed in the
complete name including the file extension, press Enter. If
the file you wish to copy has no extension you must end the file name
with a period (.).
A second prompt box will appear asking you for the name to be given to
the copy of the file. Type in the new name and press Enter.
You will be asked to confirm that you wish to copy the file. Press
Y to agree to this suggestion and initiate the copying process.
Press N if you don't want to copy the file. Consult Directory facility for more information on using
directory lists.
A prompt box appears below the Rename option asking you for the name
of the file you wish to rename. The prompt box contains the default
extension *.*. Press Enter to bring up a Directory list of all
files in the current directory. Use the cursor keys and Enter to
select the name of the file you wish to rename. If you know the name
of the file you wish to rename, type it in the prompt box. The default
file mask will disappear and the file name being typed will appear in
its place. When you have typed in the complete name including the file
extension, press Enter. If the file you wish to rename has no
extension you must end the file name with a period (.).
A second prompt box will appear asking you for the new name to be
given to the file. Type in the new name and press Enter. You will be
asked to confirm that you wish to give the selected file a new name.
Press Y to agree to this suggestion and rename the file. Press
N if you don't want to give the file a new name. Consult Directory facility for more information on using
directory lists.
The prompt box contains the default extension *.*. Press Enter to
bring up a Directory list of all files in the current directory. If
you know the name of the file you wish to erase, type it in the prompt
box. When you have typed in the complete name including the file
extension, press Enter. If the file you wish to delete has no
extension you must end the file name with a period (.).
You will be asked to confirm that you wish to erase the selected file.
Press Y to agree to this suggestion and rename the file. Press
N if you don't want to give the file a new name. Consult Directory facility for more information on using
directory lists.
Under no circumstances should you use this option to terminate your
ChemSep session. Shelling to DOS leaves a portion of memory tied up
with a program that will restore ChemSep when you "exit" the shell. To
quit ChemSep use the Exit.
ChemSep User's Guide
This menu may be reached from anywhere in the ChemSep interface using
either F10, I or Alt-I. The first four items of the
input menu are concerned with entering data:
Select Components using the cursor keys and Enter or by pressing the
highlighted letter, C. The screen will look like this:
The box in the upper right hand corner lists the components that have
already been selected. If this is a new problem (or if all previously
selected components have been deleted) the box contains the word None.
The menu lists the actions you can perform.
After the accepting the default library (CHEMSEP1.PCD) or when
searching for all PCD files (the default setting) a new menu will
appear:
The new menu lists the ways in which it is possible to find components
in ChemSep's databanks.
This is an example of a list that was created using the Search by
Class option. All components in the class Alkanes are listed in a
window on the screen. Component(s) can be added to the selected list
using the cursor control keys to position the cursor on the name of
the component you wish to select and pressing Enter. The names
of the selected components are displayed in the window on the upper
right of the screen. ChemSep will prevent you from loading the same
component more than once.
If the list contains more names than can fit on the screen the word
"More" appears at the bottom of the list. As you scroll down the list
using the cursor control keys, the word More will appear at both the
bottom and the top of the list. You will know when you have reached
the end of the list because the cursor will not go any further and the
word More appears only at the top. As in all ChemSep lists, you can
use PgUp, PgDn, Home, End to move more
quickly through the list. You may also type a few characters to move
directly to the first line with a component name that matches the
characters you typed.
By default, ChemSep lists the components in the order they appear in
the datafile. To see the list in order of the last criterion selected
you must go to the Interface item of the Options menu and turn on Sort
lists.
Component lists contain, in addition to component names (and other
information depending on the search criteria), two, or possibly three,
other lines. The additional lines of the component list are ->
Previous Search, -> Begin again, and -> additional
search. The purpose of these items is to allow you to refine the
list of components if the displayed list is too long to search by hand
or does not include the components you want. Press Esc to
clear the component list when all components have been loaded.
First, we used Search by Family to list the components in the databank
that are n-Alkanes. After that we used the "additional search" and
"search by property" to list those components that have a Normal
Boiling Point between 300 and 400 K.
Type in the prompt box the name (or any part of the name) of the
component(s) you wish to load and press Enter. ChemSep will
search its databanks and display a list of all components whose names
contain the string you entered in the prompt box. For example, typing
eth in the prompt box and pressing Enter will bring up
a list containing methane, ethane and ethanol as well as any other
components whose name contains the string eth. If you do not type
anything at all in the prompt box and press Enter, ChemSep
will display a list of the names of all the components in the
databank(s).
and select Search. Notice that the list displays the index
numbers to the left of the component names.
Notice that the list displays the structural formulae to the right of
the component names.
For example, if we select the "vapour pressure" ChemSep displays the
following prompt box:
prompting you to specify the minimum and maximum values of the
property selected. Move the cursor to the Search keyword and press
Enter to begin the search. Property searches may be conducted in
any of the units recognized by ChemSep. For properties that are a
function of temperature you will also need to provide the temperature
at which the property is to be evaluated. The search on components
with a vapour pressure between 1.0 and 1.3 bar at 100 C as specified
above results in:
A list of properties that can be used in a Search by Property Value
follows:
None of the Input information for the other components is lost by this
action. Results, however, while retained until you Solve the problem
again, do not pertain to the current set of components and are not
Saved in the problem file.
Use Reorder as many times as you need until you see the components in
the order you like them to remain. None of the Input information for
any of the components is lost by this action. Results, however, while
retained until you Solve the problem again, do not pertain to the
current ordering of components and are not Saved in the problem file.
The menu contains the following items:
Any flash should have at least one feed in order to calculate anything
useful. The maximum number of feeds is 10. After entering the number
of feeds for the flash and ChemSep continues to the property model
selection.
The nonequilibrium column and dynamic column option also use the
column spreadsheet for defining the column configuration. The
asterisks (*) indicate the fields that must be completed:
Type numbers in the Stages, Feed stages and Sidestream stages fields.
The last named is optional and may be left empty if the column has no
Sidestreams. Multiple feeds and sidestreams must be separated by a
space or by a comma. For example, if a column has two feeds to stages
12 and 25 the Feed stages line of the Operation spreadsheet should
look like this:
The cursor keys (Up, Down, Home, End) and Enter may be used to select
the operation type. The operation types determine the basic column
configuration and the K-models available. A brief summary of each
operation type as it is understood by ChemSep is given below:
The basic Condenser types are as follows:
The basic Reboiler types are as follows:
The flowsheet shows the column with the feeds and side streams as well
as the top and bottom products, selected reboiler and condenser, and
possible pumparounds. Upon completion of the operation configuration
select the Return option and ChemSep continues to the property
model selection.
The menu contains three options: Thermodynamic models,
Physical Properties and Load data. The first option lets
you select the thermodynamic models and the second the physical
property models. The latter is only required for nonequilibrium column
simulations and therefore, will not be present for flash or
equilibrium columns. The Load data option prompts you for necessary
property model data such as interaction parameters for equations of
state etc.
The validity of any results obtained with a program like ChemSep
depends on the proper selection of thermodynamic models and their
parameters. This Users Guide will not go into the technical merits of
the methods available in ChemSep. There is on-line Help available (by
pressing F1) and a technical reference file that can also be
viewed within ChemSep (with F9) that covers some basic
thermodynamics. In the rather likely event that there is insufficient
information available in the on-line help and information files we
strongly suggest you consult a thermodynamics textbook or your
friendly neighbourhood thermodynamicist (is that last word spelled
correctly). For the thermodynamically perplexed we recommend the
following sources of information:
Upon selecting the thermodynamic models option, you will see the above
window for regular columns where we contact a vapor with a liquid. The
asterisks indicate the models that need to be specified. The K-model
and enthalpy model are always needed whereas the other model
selections are only required if you select property models that use
them. After completion of the model selection
Each item in this menu represents a method of computing K-values:
Each of the options in this list represents a model for calculating
activity coefficients:
This menu appears only if EOS, Gamma-Phi or DECHEMA were selected as
K-models. Each of the options in this menu represents a model for
calculating fugacity coefficients for the vapour phase. Liquid
fugacities can only be calculated with cubic equations of state and,
therefore, they are the only available models if the EOS K-model was
selected.
The two-term virial equation is included in ChemSep:
Pv/RT=1+B. The virial model is useful for nonideal chemical
mixtures at low and moderate pressures (up to a few atmospheres).
Cubic equations of state are very widely used for computing properties
of mixtures. They are most often used for hydrocarbon mixtures (with
or without light gases) but extensions now being developed may mean
that we will soon be using this class of model for non-ideal phase
equilibrium calculations.
There are five models available in ChemSep for computing the Vapour
Pressure:
ChemSep incorporates the following methods for estimating the
enthalpy:
All the asterisks indicate unspecified models. Unlike to the
thermodynamic models, it is possible to leave the models for the
physical properties unselected! ChemSep uses a default selection of
models which is sufficient for most purposes. This selection will
depend on the selected components and operating conditions. To force a
default selection of models use the Default option on the bottom of
the screen:
You can now alter this selection by selecting each specific property.
Each has its own models associated with it. Only the selection of the
liquid diffusion coefficients is a bit different as you specify a
model for each binary component pair individually:
If left unspecified the Wilke-Chang method is default method. The
available models for liquid diffus2.4 Spreadsheets
ChemSep makes good use of simple spreadsheets for entering data. Here
is an example of the spreadsheet used for entering information
concerning the feeds.
Some spreadsheets are too large to fit in the available window. If
this happens you can use PgUp and PgDn to scroll (part
of) the spreadsheet up or down. A spreadsheet that is too large to fit
on the screen can be easily identified. The F-key bar at the bottom of
the screen is replaced by a line that tells you to use PgUp
and PgDn. The F-keys will work as described elsewhere, even
when the F-key bar is not displayed.
2.4.1 Entering and Editing Data in Spreadsheets
While using ChemSep you often have to enter a string of characters;
the title of a graph, for example, or the numerical value of some
quantity in a spreadsheet field. Position the cursor over the field
where you wish to type in a new entry (or change an old one). Simply
start typing the new value and you immediately enter Edit mode.
2.4.2 Formula Entry
ChemSep can process algebraic calculations wherever numerical input is
required. This is useful since, if you don't know the actual numerical
value that should be entered but you know how to calculate it, you may
enter the calculation. Numerical formulae may include the four basic
arithmetic operations, +, -, *, and /. Operations may be nested within
parentheses () as well. When you have typed in the formula, press
Enter to evaluate the result and Enter a second time to accept
that result. ChemSep does not remember formula entries, only the final
result so you may edit the formula until you press Enter.
3 Enter
5-2 Enter
(2-1) * (5-2) Enter
All of these result in the number 3.
573 * 0.365 Enter
573 * (1 - 0.365) Enter
2.4.3 Units Entry
ChemSep data entry fields also accept units. This feature is
particularly useful if you know a quantity in some units other than
the current set of units. You don't have to change the units (using
F5), type in the input quantity in the default unit set, and then use
F5 to change the units back again. Simply type in the numerical value
of the quantity and follow the number with its units. The number will
be displayed in the default units. For example, what if the default
flow units are kmol/s but we know the feed flows in lbmol/h? Simply
type in the feed flow as, for example,
375 lbmol/h Enter
and ChemSep will automatically convert the number to the correct value
in the default set of units. You can use this feature in any data
entry field in ChemSep. Spaces are ignored when evaluating the
expression with units. Any combination of the units listed under Other
Units may be used. ChemSep checks the dimensions of the units you
enter and displays a warning message if they do not have the correct
dimensions.
mmol/s
is recognized as (mol/s) / 1000.
2.5 Directory Facility
You will want to use the directory facility of ChemSep when, for
example, you want to load, save, view, or edit files. For example,
going to the Load option of the File menu and pressing Enter will
bring up the following screen:
%t2h!2.6 View Windows
ChemSep can display Results in Tables or in Graphs. Tables are written
in a View Window. ChemSep allows you to View text files (as long as
they fit into available memory). The contents of a file being viewed
are displayed in a View window. Here, for example, is the Streams
table for the Depropanizer illustrative example.
In a view window the cursor is positioned on an entire line. The
cursor line is displayed in a different colour from the rest of the
text in the window. If all of the lines of text appear in the same
colour it means that the cursor is on an empty line. There are four
Two-keys that have a special purpose in a View window:
2.7 Edit Windows
ChemSep allows you to Edit any Tables that are written in a View
Window. ChemSep also allows you to Edit text files (as long as they
fit into available memory). To edit a Table, you must have the table
displayed on the screen. Press Alt-E to Edit the contents of
the window. To edit a file use the Edit option of the File menu to
bring up a directory list of the file(s) you wish to Edit. In an Edit
window the cursor line is displayed in a different colour from the
rest of the text in the window. If all of the lines of text appear in
the same color it means that the cursor is on an empty line. The
cursor itself is a blinking underscore. The following keys may be used
to move the cursor in an Edit window:
Characters may be deleted using the following keys:
Other useful keys are:
Press Escape when you have finished editing the contents of
the window. Tables in an Edit window cannot be saved in their modified
form. You must Print the window (by pressing Ctrl-P) to a file
or to a printer if you want to save the contents of the edit window.
Files can be saved in their modified form. If you were editing a file
when you pressed Escape, you will be asked if you wish to save the
file. Press Y to save it (and overwrite the old version). If
you press N the file will not be saved and the Edit window
will be removed from the screen. Any changes you may have made will be
lost.
Chapter 3. The Keys to ChemSep
As noted in Chapter 2, the most important keys in ChemSep are
Up, Down, Left, Right, Enter,
Escape, and the Spacebar. To make life easier for our
users we have assigned special functions to the F-keys and a
number of Alt-key and Ctrl-key combinations. In
addition, it is possible to assign your own functions to the
Alt, Shift and Ctrl F-keys. In this chapter of the
User's Guide we review the following key assignments:
3.1 The F-keys
The keys, F1 to F10, have special functions assigned
to them. Here is a summary:
These keys can be pressed wherever you are within the ChemSep
interface. F6 causes the cursor to jump to the Solve options
item of the Options menu and is described in detail in that section of
this User's Guide. F10 causes the cursor to return to the Main
menu and needs no further discussion here or anywhere else. The
functions of the remaining F-keys are described in detail below.
3.1.1 F1 and F2 - Help
F1 may be pressed any time you are in the ChemSep interface to
display a window containing help messages. The message displayed when
F1 is pressed depends on where you are in ChemSep. Almost all
menu items have their own help message. Here, for example, is the
screen image after F1 is pressed when the cursor is on the
Name item of the Select option of the Components menu:
3.1.2 F3 - Load
F3 jumps directly to the Load option of the File menu and
executes it so that the screen looks like this:
3.1.3 F4 - Save
F4 saves the current Input data immediately. F4 can be
pressed anywhere in the interface. Pressing F4 will result in
the immediate overwriting of your file. If no file name has
been given you will be asked to provide one in a prompt box similar to
the one shown below:
3.1.4 F5 - Units
ChemSep is an engineering program and, therefore, requires units to
express numerical results. ChemSep allows you to use a wide variety of
units for entering and displaying results. All internal calculations
are carried out in SI units but are converted to the units of your
choice for display purposes. Units are selected in the Units item of
the Options menu. You may also change the default units set by
pressing F5 anywhere in Chemsep. In either case, the
spreadsheet below is displayed on the screen.
3.1.5 Unit lists
Below we list the units of all quantities that can be selected with
F5. Note that many of these unit lists contain the unit Other. This
option covers units not in the lists of recognized units and will be
explained later.
3.1.6 Other Units
Several of the unit lists contain the other unit. This option allows
you to choose some other unit that is not in the list of alternatives.
Select other to be presented with a data entry field where you type in
the abbreviation of the unit you wish to use. ChemSep recognises the
following units
Abbreviation Unit
kg kilogram
m meter
s seconds
K Kelvin
kmol kilomole
rad radian
N Newton
Pa Pascal
J Joule
W Watt
degree
lb pound
g gram
min minute
h hour
day day
UKgal UK gallon
USgal US gallon
l liter
cal calorie
Btu British Thermal Unit
in inch
" inch
ft feet
torr torr
bar bar
barg bar in gauge
lbf pound force
kgf kilogram force
atm atmosphere
psia lbf/square inch
psig lbf/sq in gauge
yd yard
ton ton
USton US ton
oz ounce
lbmol poundmole
mol mole
erg erg
dyn dyne
P Poise
mi mile
F Fahrenheit
C Celcius
F Fahrenheit
C Celcius
R Rankine
bbl barrel
Ž dimensionless
% percent
%% per thousand
ppm parts/million
ppb parts/billion
Suppose, for example, that you wanted to display molar flows in
kmol/day. This unit is not included in the list of molar flow units
although kmol and day are recognized by Chemsep. To display molar
flows in kmol/day, press F5 to bring up the units spreadsheet.
Use the cursor keys and Enter to select Flows. Use the cursor keys and
Enter to select other and type kmol/day in the field provided.
Press Enter to accept the new unit. Please note that you must
type the abbreviation and not the full name and that abbreviations are
case sensititive. ChemSep does a dimensional analysis of any unit you
type and will not let you use units (or combinations of units) with
incorrect dimensions.
3.1.7 Unit Prefixes
ChemSep recognizes the standard prefixes for multiples of 10 and they
can be used in Other units. For example: "mm" is interpreted as
"m/1000". The complete list of prefixes and their abbeviations
recognized by Chemsep is as follows:
Abbreviation Full name Power of 10
T Tera 12
G Giga 9
M Mega 6
k kilo 3
h hecto 2
da deka 1
d deci -1
c centi -2
m milli -3
m micro -6
n nano -9
p pico -12
f femto -15
All units and their prefixes can be typed in data entry fields as well
as selected to be part of the default unit set. See the section on
Entering and Editing Data for a discussion of how to use units in data
entry fields.
3.1.8 F7 - View
F7 allows you to inspect the contents a file in a View Window.
Press F7 to display a prompt box similar to that shown below
asking you for the name of the file to view. The prompt box contains
the default file mask, *.*.
3.1.9 F8 - Summary
The F8 key can be pressed anytime you are in the ChemSep
interface in order to bring up a View window containing a summary of
the problem specifications. This is a useful way to determine if the
problem has been completely specified as the necessary sections of
input data will be empty if incomplete. Here is an example of an empty
problem summary. Notice the main sections of this summary include:
Components, Operation, Properties, and Specifications. These are also
the options of the Input menu.
3.1.10 F9 - Information
The F9 key can be pressed anywhere in the ChemSep interface in
order to bring up the ChemSep Book which consists of technical
documentation of all the models and correlations used in ChemSep. This
information is stored in the "chemsep.txt" file and viewed with the
file viewer. Use the cursor control keys to scroll the file in the
window (see the section on Viewing files for a list of keys) and press
Escape to clear the window.
3.2 Alt-Key assignments
As is more or less standard practice in menu-driven software, the
various items on the main menu can be accessed by holding down the Alt
key and pressing the highlighted letter associated with that item:
Some other special functions have been assigned to Alt-key
combinations:
The difference between these last two two-keys is that if you press
Alt-S you will be asked to verify the data file name before
any existing file is overwritten. If you press Alt-Q,
automatic data checking is ignored and the current file name is
overwritten immediately. The Alt-keys can be pressed from anywhere
within ChemSep.
3.3 Control key assignments
Some special functions have been assigned to Ctrl-key combinations:
The Ctrl-keys can be pressed from anywhere within ChemSep.
3.4 User Defined Keys
One of the most useful features of the ChemSep interface is that you
have the power to assign particular tasks to no less than 30 keys. The
Alt, Shift and Ctrl -Function keys can be
programmed by the user. We consider this feature to be very useful and
use it all the time in our own work. To assign one of these key
combinations go to the Macros option of the Options menu and press
Enter. You will see a spreadsheet that lists all the current
user-defined key assignments.
3.4.1 Special Symbols for use in Macros
@ Enter
~ Escape
#aaa ASCII character where aaa is the three digit numeric code for
the ASCII character to be entered (see below for examples)
$xxx Turbo Pascal extended key code where xxx is the three digit
code used to identify certain keys in the Turbo Pascal
programming language
! Execute the macro from the current cursor position.
Macros that do not begin with this symbol are executed from
the main menu
^1 Help
^2 Last help
^3 Save file
^4 Units menu
^5 Solve options
^6 View file
^7 Units converter
^8 Edit file
^9 Summary
^0 Go to main menu
3.4.2 Turbo Pascal Extended Key Codes
$071 Home
$072 Up
$073 Page Up
$075 Left
$077 Right
$079 End
$080 Down
$081 Page Down
$059 - $068 F1 - F10
$084 - $093 Shift F1 - Shift F10
$094 - $103 Ctrl F1 - Ctrl F10
$104 - $103 Alt F1 - Alt F10
$016 Alt-Q
$031 Alt-S
$045 Alt-X
3.4.3 Examples of Macros
ChemSep User's Guide
Chapter 4. The Main Menu
Let us begin our exploration of ChemSep's interface with a quick look
at the Main menu:
In the main menu (and only in the main menu) you can use the
left and right arrow keys to move from branch to branch of
the main menu. You can use the left and right arrows
even when the submenus are hanging down from the main branch. With the
screen as shown above (just after you started ChemSep), Press
Enter and use Left and Right to look at each of
these branches.
4.1 The File Menu
If you press Enter with the cursor on File, the screen will look like
this:
Each of these items is described in detail in Chapter 5.
4.2 The Input Menu
The Input menu is the first branch of a long and complicated menu
tree. If you go to the input option of the main menu and press Enter,
the screen may look like this:
There are two more item in the Input menu:
The first four items in the Input menu are the start of a
complicated menu tree and the way the tree grows depends on how you
walk through it. We shall take a longer look at the Input menu after
we complete our look at the Main menu (Chapter 6).
4.3 The Results Menu
The Results menu allows you to inspect the results of a simulation. If
you have simulated a Column, the Results menu looks like this:
These items are discussed in more detail in Chapter 7. If you
have solved a Flash problem, the Results menu looks like this:
4.4 The Options Menu
If you go to the Options item of the main menu and press
Enter, the screen may look like this:
The Options menu is the subject of Chapter 8.
Chapter 5. The File Menu
If you press Enter with the cursor on File, the screen will look like
this:
A couple of the file menu options have short cuts assigned to
them, such as F3 for load, F4 for save, F7 for
view, and Alt-D for the DOS shell. Let us examine these
options in more detail.
5.1 Load
The Load option of the File menu allows you to load files created by
ChemSep. To exercise the Load option locate the cursor on Load and
press Enter. Alternatively, you can press L. The
screen will look something like this:
5.2 New
The New option of the File menu resets all Input data to their default
values and clears all Results. To exercise the New option locate the
cursor on New and press Enter or press N. You will be
prompted to name the new problem file:
5.3 Save
The Save option of the File menu allows you to save the Input data and
computed Results in files created by ChemSep. To exercise the Save
option locate the cursor on Save and press Enter (or you can
press S). A prompt box appears below the Save option asking
you for the name of the file to save.
5.4 Directory
The Directory option of the File menu allows you to change the current
active directory. The current directory is where ChemSep looks for and
saves files with the SEP extension. A prompt box appears below the
Directory option asking you for the name of the new current directory.
5.5 View
The View option of the File menu allows you to view files on your
disk. After selecting the view option a prompt box appears below the
View option asking you for the name of the file to view. The prompt
box contains the default file mask, *.*. Press Enter to bring up a
Directory list of all files in the current directory.
5.6 Edit
The edit option works very similar to the view option. A prompt box
asks you for the name of the file to edit. The prompt box contains the
default file mask, *.*. Press Enter to bring up a Directory
list of all files in the current directory.
5.7 Copy
The Copy option of the File menu allows you to copy a file on your
disk. You will be prompted you for the name of the file you wish to
copy. The prompt box contains the default extension *.*. Press
Enter to bring up a Directory list of all files in the current
directory. Use the cursor keys and Enter to select the name of
the file you wish to copy.
5.8 Rename
The Rename option of the File menu allows you to give any file on your
disk a new name. To Rename a file locate the cursor on Rename and
press Enter. Alternatively, you can press R. The
screen will look something like this:
5.9 Erase
The Erase option of the File menu allows you to erase any file on your
disk. You are prompted for the file to erase:
5.10 DOS Shell
The last option of the File menu allows you to shell out to the
operating system (in our case DOS). This is particularly useful if you
want to execute a DOS command that cannot be executed from the File
menu. To shell to DOS, press O or select the DOS Shell option.
ChemSep will write the contents of memory to a hidden file on the disk
and return you to the DOS prompt. Type "exit" and press Enter
to return to ChemSep. You can also make shell to DOS at any point
within ChemSep with the Alt-D.
Chapter 6. The Input Menu
The Input menu is the first branch of a long and complicated menu
tree. If you go to the input option of the main menu and press
Enter, the screen may look like this:
There are two more item in the Input menu:
The first four items in the Input menu are the start of a
complicated menu tree and the way the tree grows depends on how you
walk through it. This chapter of the User's Guide discusses all of the
various menus and spreadsheets associated with Input. Some particular
routes through Input are illustrated in Sections 9 to 11.
6.1 Components
To obtain the Components menu, go the Input option of the main menu
and press Enter. The following menu will appear:
Of course, if no components are listed in the upper right box,
the only actions you can perform are Select and Load set. Let us look
at how these actions work.
6.1.1 Select
To add components to the list choose the Select option. You will be
prompted for the PCD (=Pure Component Data) library name unless you
have selected the search all PCD files option under options -
interface.
You can use just one of these methods to find all of the
components or a combination of selection procedures. You can even use
these methods recursively. Use the Search by Name option to see a list
of all the components in ChemSep's databanks.
6.1.2 Component Lists
Here is an example of a list of components displayed by ChemSep.
To jump to the first of these three items, press Home or the
minus (-) key. Here is an example of the use of Additional Search.
6.1.3 Name
Components can be listed based on their names or any fragment of their
names. To exercise this option locate the cursor on Name and press
Enter or press the highlighted letter, N. ChemSep will
display a prompt box as shown below:
6.1.4 Index
Each component has its own index number within a specific library
file. You can display a list of components whose index numbers fall
within a range of values you choose. To exercise this option locate
the cursor on Index and press Enter or press the highlighted
letter, I. ChemSep will display a prompt box. You must enter
the minimum and maximum index numbers. The default values are 1 and
10000 respectively. Locate the cursor on Search and press
Enter. A list of all components with index numbers between these
limits will be shown on the screen. For example, if we enter 10 and
200 as the minimum and maximum index numbers as shown below:
6.1.5 Structure
Components can be listed according to their structure. To exercise
this option locate the cursor on Structure and press Enter.
ChemSep will display a prompt box for the (part of the) structure.
Entering, for example, OH in the prompt box and pressing Enter will
bring up a list of all components having an OH group in their
structure:
6.1.6 Formula
Components may be listed according to their chemical formula or part
of their formula. For example, typing C4 and pressing
Enter will result in the display of a list of all components whose
molecules contain four carbon atoms. Typing C3H6 and pressing
Enter will result in the display of a list of all components
whose molecules contain three carbon atoms and six hydrogen atoms.
6.1.7 Class
ChemSep allows you to find components that belong in certain groups or
classes. For example, alkanes and alcohols are two of the classes that
ChemSep recognizes. Locate the cursor on Class and press Enter
to display a list of classes that ChemSep recognizes. These are the
classes recognized by ChemSep:
Alkanes
Alkenes
Aromatics
Alcohols
Acids
Esters
Halogen compounds
Amines/imines
Inorganics
Use the cursor control keys and Enter to select the class of
interest. All components in the selected class will be displayed on
the screen. For example, selecting Alkanes from the list of classes
might result in the following list:
6.1.8 Family
ChemSep allows you to list components that belong in certain groups or
families. ChemSep recognises 56 different families. Water belongs to a
family of one. Several families may fall into just one class.
n-Alkanes and other alkanes are families in ChemSep both of which fall
in the alkanes class. Locate the cursor on Family and press
Enter to display a list of families that ChemSep recognizes:
1 n-Alkanes
2 Methylalkanes
3 Cycloalkanes
4 Other alkanes
5 1-Alkenes
6 Other alkenes
7 Alkadienes
8 Alkynes
9 n-Alkylbenzenes
10 Other alkylbenzenes
11 Other monoaromatics
12 Polyaromatics
13 Miscellaneous hydrocarbon rings
14 Inorganic gases
15 Aldehydes
16 Ketones
17 n-Alcohols
18 Other alcohols (phenols)
19 Aromatic alcohols
20 Polyols
21 n-Aliphatic acids
22 Other aliphatic acids
23 Aromatic carboxylic acids
24 Anhydrides
25 Formates & acetates
26 Other saturated aliphatic esters
27 Unsaturated aliphatic esters
28 Aromatic esters
29 Ethers
30 Epoxides and peroxides
31 Aliphatic chlorides
32 Aromatic chlorides
33 C/H/Br compounds
34 C/H/I compounds
35 C/H/F compounds
36 C/H multihalogen compounds
37 Aliphatic amines
38 Aromatic amines
39 Other amines and imines
40 Nitriles
41 C/H/NO2 compounds
42 Other C/H/O/N monofunctional compounds
43 C/H/S compounds
44 Polyfunctional C/H/O
45 Polyfunctional C/H/O/N
46 Polyfunctional C/H/O/S
47 Polyfunctional C/H/O/halide
48 Polyfunctional C/H/N/halide (O)
49 Organic-Inorganic compounds
50 Inorganic acids
51 Inorganic bases
52 Sodium salts
53 Other salts
54 Elements
55 Inorganic halides
56 Other inorganics
57 Water
6.1.9 Property Value
ChemSep even allows you to list components that have some desirable
property value. Any of the several tens of pure component data values
recorded in the data bank may be used as a basis for selecting
components. Even temperature dependant properties can be used. For
example, the vapour phase heat capacity at 450 K. If you press
Enter with the cursor on the Property option you will see a list
of properties that are recorded in the data bank. Select the property
you wish to use as a basis for listing components and press
Enter.
Fundamental Properties
1 Critical temperature
2 Critical pressure
3 Critical volume
4 Critical compressibility factor
5 Normal boiling point
6 Melting temperature
7 Triple temperature
8 Triple pressure
9 Molecular weight
10 Liquid molar volume
11 Acentric factor
12 Radius of gyration
13 Solubility parameter
14 Dipole moment
15 Van der Waals volume
16 Van der Waals area
17 IG heat of formation
18 IG Gibbs energy of formation
19 IG absolute entropy
20 Heat of fusion melting point
21 Heat of vaporization at the normal boiling point
22 Standard net heat of combustion
Temperature Dependent Properties
23 Solid density
24 Liquid density
25 Vapour pressure
26 Heat of vaporisation
27 Solid heat capacity
28 Liquid heat capacity
29 Ideal gas heat capacity
30 Second virial coefficient
31 Liquid viscosity
32 Vapour viscosity
33 Liquid thermal conductivity
34 Vapour thermal conductivity
35 Surface tension
36 Ideal gas heat capacity (Reid et al.)
37 Heat of formation
38 Antoine
39 Liquid viscosity (Reid et al.)
Miscellaneous Properties (not available for all components)
40 V* (parameter in COSTLD liquid density model)
41 Lennard Jones diameter
42 Lennard Jones energy
43 Rackett parameter
44 Fuller Schettler Giddings diffusion volume
45 Surface tension at the normal boiling point
46 Parachor
47 Specific gravity
48 Chung association parameter
49 SRK Acentric factor
50 Wilson Volume
51 UNIQUAC R
52 UNIQUAC Q
53 UNIQUAC Q'
54 Peng-Robinson-Stryjek-Vera (PRSV) EOS k1
55 PRSV EOS k2
56 PRSV EOS k3
57 Chao Seader acentric factor
58 Chao Seader solubility parameter
59 Chao Seader liquid volume
6.1.10 Delete
To delete a component from previously selected components, locate the
cursor on the Delete option of the Components menu and press
Enter. This brings up a list of components that you can delete
plus an extra option which will delete all the components.
Use the cursor keys (or first letters) to select one component to be
removed from the list. Press Enter to delete that component.
You will see a message box asking you to confirm your decision.
You may delete all the components in one step using the All option at
the end of the components list.
6.1.11 Substitute
Locate the cursor on the Substitute option of the Components menu and
press Enter to bring up a list of components. Use the cursor
control keys (or first letters) to select a component you wish to
replace with another. Press Enter to bring up the Search menu,
where you can use any of the Search methods to find another component
to take the place of the selected component. The list in the top right
corner of the screen will show that one component name is different.
6.1.12 Reorder
Locate the cursor on the Reorder option of the Components menu and
press Enter to bring up a list of components under the heading
"Swap". Use the cursor keys (or first letters) to select one of the
components from the list. Press Enter and you will see the
same list of components under the heading Swap with. Use the cursor
keys (or first letters) to select another of the components from the
list. Press Enter to see the two selected components
interchanged in the list in the top right corner of the screen.
6.1.13 Save Set
Any set of selected components can be saved in a text file for use on
a different occasion. This can save you the trouble of searching the
databanks for the components you want. To save a set of components
locate the cursor on Save set and press Enter. You will be
prompted for the name of the file you wish to use to record the names
(and library information) of the components you have selected. Type in
the name you wish to use for recording the list of selected
components. If you do not use an extension the file will be given the
extension .PCS. If you wish to overwrite a PCS file that already
exist, press Enter to bring up a Directory list with the names
of all files with a PCS extension. Use the cursor control keys and
Enter to select the name of the file you wish to overwrite.
6.1.14 Load Set
Any set of components that was saved using the Save set option of the
Components menu may be reloaded into ChemSep. This will save the time
needed to Search the databanks for the components you wish to use. You
may add to and delete components from any list of selected components
once they have been loaded. To load a component set locate the cursor
on Load set and press Enter. A prompt box will ask you for the
name of the file you wish to load: The default file mask is *.PCS.
Press Enter to bring up a directory of all files with the .PCS
extension. Use the cursor control keys to select the name of the file
you wish to load and press Enter to perform the load operation. If you
know the name of the file you wish to load, you may type the name in
the prompt box. Any wild card characters (* or ?) will bring up a
Directory list of all files matching the file mask. Once the
components have been loaded, their names will appear in the Components
box in the top right hand corner of the screen.
6.1.15 ChemLib
The ChemLib option allows you to switch to the ChemLib program
which allows you to check and edit pure component data libraries.
6.2 The Operation Menu
The Operation menu contains up to three items:
The default Operation is Column. This means that if a New
problem is being created the cursor will initially be located on
Column when the Operation menu is invoked.
6.2.1 The Flash Operation
Locate the cursor on the Flash option, and press Enter to
select the flash operation. The only configuration that is necessary
for the flash operation is the specification of the number of feeds:
6.2.2 Column Spreadsheet
With the cursor on Column, press Enter (or press C) to
bring up the Column spreadsheet:
To choose the Operation, Condenser, and Reboiler types, locate
the cursor on the appropriate field indicated by the asterisk and
press Enter. The lists of allowable choices will be displayed
(see below for details).
Feed Stages 12,25
or like this:
Feed Stages 12 25
Examples of completed spreadsheets may be found in the Depropanizer
and Extractive distillation examples. Pumparounds (only available for
complex columns) are also entered here. To handle a liquid pumparound
from stage 20 to 10 enter:
Pumparounds 20>10
where the larger than sign indicates the flow direction. Separate
multiple pumparounds by spaces or comma's.
6.2.3 Operation List
Locate the cursor on the Operation field of the Operation spreadsheet
and press Enter to bring up the Operation list:
6.2.4 The Condenser List
Locate the cursor on the Condenser field of the Operation spreadsheet
and press Enter to bring up the Condenser list:
Two product condensers can be simulated in ChemSep by selecting
a Partial condenser and withdrawing a Sidestream from Stage 1.
6.2.5 The Reboiler List
Locate the cursor on the Condenser field of the Operation spreadsheet
and press Enter to bring up the Reboiler list:
6.2.6 Show Flowsheet
Locate the cursor on the "Show Flowsheet" field of the Operation
spreadsheet and press Enter to see the column configuration:
6.3 The Properties Menu
The Properties menu is accessed from the Input menu by pressing
P:
6.3.1 Thermodynamic model selection
6.3.2 Equilibrium Models (K-values)
To bring up the list of K-models available in ChemSep, locate the
cursor on the asterisk next to the K-models and press Enter:
Use the Help system ( F1) or the technical information
( F9) to learn more about these models.
6.3.3 Activity coefficient models
The Margules, Van Laar, NRTL and UNIQUAC models require binary
interaction parameters. These parameters can be entered from the
keyboard or loaded from a file on disk in the Load data option of the
Properties menu. If you select one of these models but fail to specify
a complete set of the interaction parameters, then UNIFAC is used
automatically to compute any unspecified parameters.
6.3.4 Equation of state
The Cubic and Hayden-O'Connell Virial models require binary
parameters. These parameters can be entered from the keyboard or
loaded from a file on disk in the Load data option of the Properties
menu. If you select one of these models but fail to specify a complete
set of the interaction parameters, then any unspecified parameters are
set equal to zero.
6.3.5 Vapour pressure models
6.3.6 Enthalpy models
Consult the Help system ( F1) and the technical reference
file ( F9), for further information. The default option is
Excess.
6.3.7 Physical properties
The nonequlibrium model requires physical properties such as
densities, viscosities, and surface tensions, to calculate mass
transfer coefficients and operating parameters such as pressure drops.
By default, ChemSep doesn't select any method:
