Abstract: An apparatus (10) and a process for generation of energy through organic Rankine cycle (ORC) in which the heat exchanger (70) is of the hairpin type, so as to make the apparatus more flexible and optimise the cycle efficiency. The hairpin heat exchanger is able to stably carry out the preheating, once—through evaporation and superheating steps both at the nominal load and at the partial and transitory loads, either for sub-critical ORC cycles or for super-critical ORC cycles.

Abstract: An expansion turbine, comprising: a case having an inlet and an outlet for a working fluid; at least one stator (3) installed inside the case; at least one rotor (2) installed inside the case and rotating around a respective revolution axis (X-X); a short-pipe (4) constrained to the case; a mechanical unit (5) installed inside the short-pipe (4). The mechanical unit (5) comprises a bushing (7) and a shaft (6) rotatably installed inside the bushing (7). The shaft (6) is connected to the rotor (2) in removable manner and the whole mechanical unit (5) inclusive of the shaft (6) is extractable from the short-pipe (4) in a unitary form from the side opposite to said rotor (2).