Flow Sheet Solver 2

[nrgeng]

I recently encountered a problem with the solver similar to the previously reported problem but simpler. My intent is to document this problem with the hope that its solution will help to make COCO even better that it already is. Please see the attached Flow Sheet Block Diagram.

Simplified Representation of Flow Sheet

Flowsheet Block Connections 2.JPG (69.24 KiB) Viewed 5661 times

The simulation can best be described as two blocks of Units interconnected within the block and with the two blocks connected with each other by a material stream, 93, and an energy stream, 32. The problem is that the two streams must be manually severed for the flow sheet to converge. After adding two "helper" streams, 93-H and 32-H; when the blocks separately converge, then the streams are updated manually until they are close enough to attempt a reconnection. This is a tedious and laborious procedure, a procedure which is best given to a computer, but with this problem, is not the case for it can only solve with manual intervention. (The residual remains the same number for the duration of iterations configured.)

Why does not the solver perform what seems to be a simple but laborious task? Is this problem worth including in the COCO To-Do List along with the problem of incorporating fast reactions in an Equilibrium Reactor Unit? Any advice or comments are solicited.

[jasper]

You can see where the solver attempts to cut, if you put the info level to Debug in Flowsheet Options. Presumably it cuts only the heat stream?

Which streams do you need to disconnect? Presumably only the heat stream, as this eliminates all recycles? In this case I am not sure what you mean with "converge"; it would not need to iterate at all.

Can you send me the flowsheet?