After carrying out basic material & energy balances this module is used to examine various plant stream details and their physical properties. Various utilities viz. Pressure Calculations , Heat Loss Calculations; and Data Export are also available.

To add 2 streams :
1. Select the first stream and mark the stream as "Mark Stream-1".
Stream is selected by placing the mouse cursor in any cell in a row and
pressing left mouse button. The selected cell appears highlighted. The
row containing selected cell is the selected stream. Selected stream can
be marked as 1 or 2 by pressing "1" "2" buttons on the tool bar or from
the pop-up menu. The pop-up menu appears on right clicking the mouse
button.
2. Select the second stream similarly and mark as  "Mark Stream-2".
3. After marking the streams as 1 & 2, select a stream with empty data
(basically a stream to hold results of addition).
4. Now pressing tool bar button "+" will add these 2 marked streams and
resulting stream will be displayed. This stream addition simulates
physical mixing of 2 streams. You can add various type of streams viz.
acid, oleum, water, steam  with acid, water, oleum, steam in any combination;
air, gas, water, steam with air, gas, water, steam in any combination.

There is another button with Sigma summation face on it. This is used
for adding all the stream begining at first stream upto second stream.
This is basically helpfull, when you have more than 3-4 stream coming to
a equipment and want to know resulting stream. You can place all the
streams in continous rows and sum them all up. The procedure is same as
earlier. Only in this case you press button with Sigma sign.

In case of subtraction, it is only flow rate substraction, and not
physical tearing of streams. I have not yet been in postion to simulate
physical tearing of streams, basically due to lack of time & need. to do
so.