Splitter - same composition

Hello,

I use STAN mainly for water/wastewater balances: factory wide, treatment plant, ... .

A common operation is splitting an incoming flow into 2 or more flows: buffer tank, pump stations, recycle flows, ... .
Since there are no physical or chemical operations in the splitter, all outgoing flows must have the same composition.

Currently, STAN does not make any default assumptions on the outgoing flows.
If the composition cannot be determined from the balance, you have to specify it explicitly, either hardcoded or via relations (= influent composition).
I prefer using relations, since these will pick up any changes made in the ingoing flows, but it can become laborious with many flows/parameters.

Suggestion:
Add an option, e.g. "is splitter", to a process to indicate that all outgoing flows have the same composition.
Under the hood, this could generate additional constraints for each layer (except goods) that all outgoing  flows have equal composition.
Or, sets the loads for each outgoing flow and layer (except goods) proportional to their flowrate (goods).

Best regards,
Geert



 

Hi Geert,

Thanks for your suggestion! Definitely an interesting idea. I will add it to our wish list.

In the meanwhile, to make data entry more convenient, you could rearrange the grouping hierarchy of the flow values like shown in the screenshot (by dragging and dropping the respective column descriptions into/out of the grey area).

 

If you now select the rows stating the composition of the inflow (most easily by dragging your mouse pointer over the respective blue squares in front of the rows), you can copy the information by pressing CTRL+c. If you then select the composition rows of an outflow in the same way and press CTRL-v, the information is pasted. The later procedure has to be repeated for all outflows of the process.

All the best,

Hi,

I use the Explorer almost exclusively to add raw data, much easier than swapping layers in the flowsheet.

Regarding splitters:
Typically, the outflows are calculated from the mass balance, not entered as raw values.
Therefore, one can only add the relation(s) that the outflow compositions are equal.


Best regards,
Geert

While adding your suggestion to our wish list, I realized the following issue:
What if a process has more than one input flow? Then, the composition of the outfows would be a mixture of the composition of the inflows. Otherwise the "splitter" option would relate to processes with a single inflow only, what is in my opinion a little bit restricting. So the rule should be: the composition of all outflows is equal. Do you agree?

Hi,

Yes, the condition for a splitter should be that the composition of each outgoing flow is equal.

Whether it has one or more inflows has no influence on this condition.

Best regards,
Geert