Consulting on ProcessWaterCenter (PWC)

Hello, may I ask you some questions about ```ProcessWaterCenter (PWC)```? Thanks for your help. Wish you a good day.

a) Hello, may I ask you how to use ```PWC```? I have checked the relevant tutorial, there are 4 import streams in the tutorial (https://biosteam.readthedocs.io/en/latest/API/facilities/ProcessWaterCenter.html#:~:text=ins%20(AbstractStream,up%20process%20water), but why only 3 import streams when using ```PWC``` (https://biosteam.readthedocs.io/en/latest/tutorial/Building_a_biorefinery.html#Unit-operations-and-simulation:~:text=ins%3D(bst.Stream()%2C%20makeup_water%2C%20P303%2D0)%2C)? Do ```makeup_water_streams``` and ```process_water_streams``` have to be set (https://biosteam.readthedocs.io/en/latest/tutorial/Building_a_biorefinery.html#Unit-operations-and-simulation:~:text=makeup_water_streams%3D(,.boiler_makeup_water)))? If so, how should it be set, that is to say, what streams should be included in ```makeup_water_streams``` and ```process_water_streams```?

b) When calling ```PWC```, do I need to set anything else besides ```ins```, ```outs```, ```makeup_water_streams```, ```process_water_streams```? Can I not set ```outs```, ```makeup_water_streams```, ```process_water_streams```, that is, can I just set ```ins```?

c) May I ask you how to set up ```ins```, is there a requirement for the order and number of streams in ```ins```? For example, does ```ins``` have to have four streams?

d) I tried the following two different codes using ```PWC``` in my own process (```S604``` is ```S604``` in the cellulosic model, exit stream is RO treated water, ```P403``` is ```P403``` in the cellulosic model, the exit stream is recycle process water), but the calculated amount of process water required by ```PWC``` is not the same, may I ask you why?
The two codes are as follows.
The first code:
```
bst.facilities.ProcessWaterCenter('PWC',
(S604-0, 'makeup_RO_water', P403-0, 'makeup_process_water'))
```
The second code:
```
bst.facilities.ProcessWaterCenter('PWC',
(P403-0, S604-0))
```
e) Like the inlet stream ```cellulase``` stream of ```M301(enzyme hydrolysate mixer)``` in ```cellulosic model```, which also has water, will the process water required for the process take this part into account? Or does BioSTEAM consider only the flow rate of an inlet stream whose components contain only water?

f) Why does the ```process_water_streams``` in the tutorial include ```s.cooling_tower_makeup_water, s.boiler_ makeup _water``` (https://biosteam.readthedocs.io/en/latest/tutorial/Building_a_biorefinery.html#:~:text=s.cooling_tower_makeup_water%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20s.boiler_makeup_water))), shouldn't they be ```makeup_water_streams```? According to the tutorial, ```process_water_streams``` refers to the all inlet process water streams (excluding makeup water streams) (https://biosteam.readthedocs.io/en/latest/API/facilities/ProcessWaterCenter.html#:~:text=process_water_streams%20(List%5BStream%5D%2C%20optional)%20%E2%80%93%20All%20inlet%20process%20water%20streams%20(excluding%20makeup%20water%20streams)).

g) For ```makeup_water_streams=(BT-1, CT-1)``` (https://github.com/BioSTEAMDevelopmentGroup/Bioindustrial-Park/blob/master/biorefineries/cellulosic/systems/cellulosic_ethanol.py#L56), ```BT-1, CT-1``` refers to blowdown water, not makeup water, why does ```makeup_water_streams``` include ```BT-1, CT-1```?
For ```process_water_streams=process_water_streams```, why does ```process_water_streams``` include ```BT-1, CT-1``` (https://github.com/BioSTEAMDevelopmentGroup/Bioindustrial-Park/blob/master/biorefineries/cellulosic/systems/cellulosic_ethanol.py#L57, https://github.com/BioSTEAMDevelopmentGroup/Bioindustrial-Park/blob/master/biorefineries/cellulosic/systems/cellulosic_ethanol.py#L47)? It should be ```process_water_streams``` refer to all inlet process water streams (excluding makeup water streams) (https://biosteam.readthedocs.io/en/latest/API/facilities/ProcessWaterCenter.html#:~:text=process_water_streams%20(List%5BStream%5D%2C%20optional)%20%E2%80%93%20All%20inlet%20process%20water%20streams%20(excluding%20makeup%20water%20streams))

Start with the ProcessWaterCenter API documentation and the Building_a_biorefinery tutorial, then compare the referenced cellulosic_ethanol.py lines 47, 56, and 57. Trace how ins, makeup_water_streams, and process_water_streams are used in the PWC implementation. Done means the stream semantics and the tutorial/model discrepancies are documented clearly, with corrected examples if needed.

Written by the indexing model from the issue text.