Education

Conventional Representation of a process structure.

P-Graph is a bipartite graph. One set of nodes (horizontal bars) represents the operating units and the other (solid circles) the material streams. There is no arc between two operating units. Relations of the operating units are realized through material streams, i.e., an operating unit is connected to another if one of them consumes a material produced by the other. In P-Graph representation there are arcs from each input material (stream) to the operating unit consuming it and from each operating unit to its output materials (streams).  

P-Graph represenation of the process structure.

 

The aim of process structures is to produce certain materials. Design alternatives are different process structures resulting in the same product. If a merial is produced by more than one operating unit, it can be produced by one, by an other, or any combination of them. For example, material E can be produced by operating unit O1, O2, or both of them. Based on this information the algorithms using P-Graph can take into account all the candidate design altenatives. In a P-Graph inputs to an operating unit are necessary inputs, e.i., each of them have to be available in order to use the operating unit. For example, material E and F are both necessary inputs to operating unit O4, that is why operating units O2 and O3 are not alternatives to each other.

P-Graph Studio

1. To download the software, first You have to visit http://p-graph.org/pgraphstudio/ and click on the Install button.

2. Then You should select Save File to download it on Your computer.

3. After the download You may click on Setup.exe, this will start the installation process.

4. Since the publisher is University of Pannonia, You can trust the publisher and click Run.

5. Next You have to accept the terms of License Agreement.

6. A reboot will be needed to continue.

7. If the question in connection with the publisher is dropped again, click Run again.

8. The question is also asked considering the name of the software and the source of it.

9. The opening screen of the PNS Studio can be seen below.

10. To register or login You have to click on the Login/Register button visible on the right up corner.

11. Next You have to enter the validation code which comes onto the email address given earlier.

12. The validation code can be found in the email. It has to be copied on the clipboard by clicking with right mouse and click Copy.

13. Paste it into the Validation form.

14. Click OK.

15. This is the end of the registration phase. You can click OK.

               16. Finally You can log in with the registrated user name and password.

If we want to determine the optimal solution, we have to set the most properties of the considered graph. Let us take a look at the following example with the given properties:

Next, You should choose an algorithm and enter the maximum number of solutions (Solutions limit). We also can give a set of mutual excluded operating units by hitting the “Mutual exclusions” button. Then just simply click on the “Solve problem” button to start the solver.

After a complete execution You should select the “Solution” tab and click on the drop-down menu, where You find all the solutions.

Choosing a solution, You can see the structure by disabled elements given with gray color.  The properties (i.e. the quantities, prices, etc.) of the elements of a chosen solution can be seen on the “Solutions” panel.

 

Steps of the calculation:

• Calculate or estimate cost c1 of the operating unit of unit size (defined by the flowrates of input and output materials)
• Calculate or estimate cost c2 of the operating unit of double size (defined by double flowrates of input and output materials)
• proportionalcost = c2 − c1
• fixcost = c1 − proportionalcost