Why PS-SFC is Expensive

The physico-chemical properties of the supercritical fluid being strongly dependent on pressure and temperature, means that these two parameters must be closely controlled all along the process, which must include 6 closed-loop regulation systems. As can be seen on the eluent cycle (Fig. 7-1), the PS-SFC process requires 3 or 4 different temperature levels and as many heating or cooling systems which must be added to the investment cost. 

Finally, safety systems related to the manipulation of high pressure compressible fluids are necessary all along the process loop. Strict parameter control, safety control and periodic valve actuation requires an automation system the operator controls the process through a computer. 

All these points justify that the investment cost represents typically 51% of the total purification cost (see example below). 

---