Using ASPEN on the Rensselaer Computing System

To use aspen, you need to do the following:

First of all, ASPEN only runs on the IBM workstations, so log-in on an RS/6000 workstation (details for using ASPEN on the PC's in the Merck Computer Lab will be provided later).

We recommend that you create a directory for your ASPEN files using in process design:

   mkdir cpc_aspen
Now you can change to that directory:

   cd cpc_aspen

To run ASPEN type the following, so that ASPEN "knows" that you have permission:

    source /big/02/0002/aspen.profile
To actually start ASPEN, type (remember that you may wish to do this from a new directory that you have created for your aspen runs)

>> submit to ASPEN PLUS on this node?


>> connection established


>> open an existing run (or, click the icon for creating a new run)

(I recommend that you begin to learn aspen by completing a flash calculation in the ASPEN examples library)
>> select format of run to open

    backup format



>> you will be presented a flow diagram for a flash unit with 1 feed and 2 product streams. I suggest that you solve this for a feed mixture of 50 lbmol/hr MeOH and 50 lbmol/hr water, at 180 deg F and 20 psia. Let the flash drum operate adiabatically at 1 atm (absolute).
    begin by clicking on the icon for stream 1 and using the right mouse button to select INPUT

    then enter 180 deg F, 20 psi and 50 lbmole/hr each for the values of methanol and water

    press the NEXT button -- ASPEN will display a screen for the flash specifications. enter 0 duty and 1 atm (change the units from psi to atm by using the right mouse button on the units slot).

    select the NEXT button -- you'll find that all the inputs are specified and you can begin the simulation.

after the simulation is complete (this will take longer than you think, since quick restart was not used), click the next button again -- 

>> your simulation has completed normally. Results are present. Display Run-status results form?


you can now browse the results by continuing to press the >> button.

At any time you can use the HELP button.

When you are done, close the report window, and select EXIT under the FILE menue bar.

Do not bother saving this run.


You may need to request a disk quota increase (which you can do online) in order to handle larger ASPEN runs.

(from the RPI Consulting homepages on the World Wide Web)

Subject: Updating Your RCS Account Quota

Software Category: Utility

Supported by:Information Technology Services -------------------------------------------------------------------------------


An RCS program, quota_request, enables you to increase or decrease your disk space on RCS.


Getting Started:

To increase or decrease your quota, enter the following command at a UNIX prompt, replacing # with the total disk space (in megabytes) that you want:

        quota_request -quota #
For example, to set your disk quota to 20 MB, you would enter the command:
        quota_request -quota 20
Current charges are 25 cents per megabyte per month for up to 50 MB; each additional megabyte over 50 MB costs 15 cents per megabyte per month. Please note that you will be charged for extra disk space whether you are using your account or not. Therefore, if you are going to be away for a semester or more, or you leave campus during the summer, you might want to clean up your files and reduce your disk quota.



Enter the command quota_request at a UNIX prompt to see the various options for the program. There is no other documentation.


Tips and Hints:

Disk quota increases are limited to a total of 250 MB.

To reset your disk quota to its default size (5 MB for students, 10MB for faculty and staff), enter the following command at a UNIX prompt:

        quota_request -reset
It can take up to 24 hours to process a quota change request; you will receive electronic mail confirming the completed transaction.


Possible Problems and Solutions:

If you want to increase disk space for a /locker directory, you need to go to the ITS Help Desk in the VCC or CII 3111 and fill out a /locker quota change request form. A signature is required.