130°C is quite feasible for a FWKO treating bitumen emulsion. The pressure will be a few bar g. To get the desand water from your skim tanks into the FWKO you will probably have to pump it anyway which gives you the opportunity to heat it up without it boiling, and thus reduce the impact on...
My recollection is that scaling in the heat exchangers is the main concern above 40-45°C Tube wall temperature. You could also get scaling and plugging of the spray nozzles in the cooling tower.
I think this issue will also depend on the number of concentration cycles and the hardness of the...
Thanks MortenA for correctly distinguishing the thermodynamic changes undergone by the fluid left in the vessel and the fluid expanding through the nozzle.
The fluid in the core of a vessel can - with a large pressure drop - eventually fall to a very low value (Isentropic or Joule expansion)...