Just to remind you: I have no experience with designing this kind of systems.
Also note that a simplified flow scheme is not the same as a design.
It seems to me that to design this you need to know more about the NaCl crystals that form, such as size, hardness, particle density, and also composition: will it be pure NaCl crystals, or will the NaCl crystallize as a hydrate such as NaCl.2H2O or whatever. Formation of hydrates obviously has a big impact on the H2O balance, and consequently on the heat balance of the system.
Check whether the brine only contains NaCl or also other salts that are less soluble (e.g. carbonates) and may cause deposits in the PHE and other equipment.
When you take the circulating brine from the very bottom of the separator I fear that you will catch more solids in the filter press than in the Nutsche filter. I would consider to take the circulating brine from the large diameter part of the separator, via a special internal, and have a separate pump to feed the Nutsche filter from the very bottom.
If you use Wide-Gap PHE I don't think you will then need that filter press.
Pumping brine with crystals, ask yourself: what does that do to the crystals, and to the pump.
I don't know anything about Nutsche filters, so I cannot comment on the choice of that particular kind of filter. Is that continuous operation with automatic removal of solids, or does this require operator action every time solids need to be removed.
You want to reuse the water from the condensor, so you need to minimise any entrainment of brine from the separator.
Location of the backpressure valve / orifice relative to separator inlet may need special attention. If you were flashing pure water it would not really matter, but in this case I am not sure.