Carnot is dead, long live LESA !

[not_a_mib]

The 180C boiler temperature would probably rule out a conventional liquid-refrigerant heat pump.  A Stirling cycle could be used.  (A Stirling engine turned backwards will act as a heat pump, and can be made to nearly reach the Carnot limit.  A common working fluid is helium gas under high pressure.)

The heat-pump COP would be low due to the Carnot limit.  This could be helped by drawing from a source of low-grade heat that would otherwise be wasted, such as the boiler-furnace flue gas.  The Schaeffer cycle itself could provide some of the heat, their diagram shows the first-stage water-separation tank running at 100C.  It probably needs to dump some heat into a "cold pole,"  but not as much as a Carnot-limited cycle.  Such heat could be fully-recovered by the heat pump as long as the Schaeffer cycle exceeded the Carnot limit by enough to cover losses.