Information Calculator Unit Configuration

[nrgeng]

The Information Calculator (IC) Unit is a very useful tool. I am pleased that it is provided in COCO.

I have been encountering a series of "problems" with the IC Unit. This is my first posting on the subject regarding these problems. I will e-mail (see private message) a fsd file that exhibits the problems. Here is the list. I suggest a review of my simulation and then configuring it from scratch yourself.

Information Calculator (IC):
1) select IC Unit from Menu then connect output, Z1
2) configure Unit (GUI): inputs, X1 & Y1; output; & formula
GUI [Ports] dialog displays inputs & output
3) no inputs show in Unit [Ports] dialog
a. must add then delete virtual port to update Unit [Ports] dialog
4) change Y1 to Y2
a. displays in GUI [Ports] dialog
b. must add then delete virtual port to update Unit [Ports] dialog
with name change
5) Stream Z1 not displayed in Stream Report
6) change Y2 to Y3: same Problem as #4 above
7) Document Explorer does not update for existing streams when
IC variable name is changed, i. e., Stream Y1 when IC variable
name is changed from Y2 to Y3
8) more later...

I hope you can help.

[jasper]

It seems to simply be a problem with COFE updating the dialog after hitting Edit at the Status page; the button at the Edit page did this ok.

Can you check if the problem is resolved now? (CUP). Thanks for reporting this.

[nrgeng]

All resolved except Item No. 6 remains with COFE 2.6.0.17. If you change Y3 to Y4 in the GUI, then close the Unit Configuration, you will generate an Error Message during an attempt to solve the flow sheet. (Unless you follow the Procedure of 4.b before closing the Unit Configuration.)

[jasper]

I cannot reproduce this issue. I do get a problem if I do not update the formula accordingly, and as a result of the port name changing the stream disconnects. So the stream has to be reconnected.

Let me know if you find something else.

[nrgeng]

The problem remains. I am not sure why you were not able to detect this problem. We are using the same fsd file. Every time I obtain the message, "Solve failed: incomplete or invalid specification for unit Ratio: not all inlet information ports are connected."

My procedure is (1) initialize the problem by solving the flow sheet, (2) open the GUI Dialog, (3) change the input variable name from Y5 to Y6, (4) change the output formula from Y5 to Y6, (5) close the GUI dialog, (6) solve the flow sheet. The flow sheet fails to solve for the above reason. An inspection of the flow sheet shows that all the inlet ports are connected. By following the procedure in Item 4.b above, the flow sheet will solve.

The Ports dialog when accessed from the GUI dialog shows the updated input variable as Y6. The Ports dialog when accessed from the Unit dialog shows the updated input variable not as Y6 but as the old Y5. That is the problem to be resolved with your help. I hope that you can duplicate the problem. Feel free to request a new fsd file with the problem installed.

[jasper]

Can you send me an fsd and exact steps to reproduce it again? I am having trouble getting the failure you describe. In all cases I try, the port disconnects and needs to be reconnected.

[jasper]

Found it. I found a related error that caused the order of the variables to be mixed up in some cases. Also fixed. Finally I made it so that renaming a variables causes the port to be renamed rather than removed and re-added, so that the stream no longer disconnects (and no longer looses its value). However, this does not automatically cause the stream variable to get renamed; for this disconnecting and reconnecting the port remains required.

Fix is available in COUSCOUS (2.6.0.17), available via CUP. Thanks for reporting.

[nrgeng]

One of the changes is good but does not go far enough in my opinion. What follows is what I saw when I changed an input variable name.

1) Change the input variable name from Y5 to Y6 for information stream Y1
The Unit [Port] Dialog now matches the GUI [Port] Dialog directly after the input variable is renamed. This is a good result.

2) Validate the flow sheet: "The flowsheet specification is complete."
Is the flow sheet really valid?

3) Solve the flow sheet: The flow sheet solves.
There is no input variable named Y5 any more, yet the old input variable name is displayed in the Stream Report and in the Document Explorer Stream Window. Is not this dangerous because the revised input variable name, Y6, is not shown, but the old one, Y5, is? Does not this represents an error in the flow sheet?

so that the stream no longer disconnects (and no longer looses its value)

It is desirable for the information stream (and energy streams) to not loose its value since material streams do not loose their values when disconnected.

However, this does not automatically cause the stream variable to get renamed; for this disconnecting and reconnecting the port remains required.

Why does the information stream have to be disconnected and reconnected? When it is, it looses its value so what has been gained? I have to record the stream value before I disconnect it because its value will be lost otherwise. I can remember 1 (in this example) just fine, but 1.7649034 is more difficult to remember at least for me. Is there another method available to update the information stream, Y1, with the revised input variable name, Y6, rather than disconnection and reconnection?

[jasper]

The information in a material stream is phase equilibrium for the compounds defined by the property package associated with the stream. In other words, the information is inherent to the stream. Not so for information streams. They get populated based on whatever they connect to. So it does not make sense to have a stream that is unconnected that still carries information.

If an information stream is connected on two ends, the first end connected will cause the information stream content to be populated. Then connecting the other end should only be allowed by the port of the data on the stream is considered a match. That is, it would be up to a unit operation to refuse to couple an information item that carries the unit of measure kg/s to data that carries unit of measure K/m. Still, typically the names on both ends would be different, so unit operations should not care too much about the name of the corresponding item on the information stream.

I suppose however I could supply functionality to rename the data on an information stream. Will do so in a next update.

[jasper]

(note, copy / paste works, you don't have to actually remember the value).