Power generation system and method to generate power by operation of such power generation system

A method to generate power by operation of a power generation system (1), the power generation system (1) comprising:

• a liquid pump section (4) comprising an inlet and a rotary liquid pump (7) with an impeller in which a working fluid is pressurised and which is driven by a drive shaft (8);
• an evaporator section comprising an evaporator (9) in which the in the rotary liquid pump (7) pressurised working fluid is at least partly evaporated by addition of heat from a heat source;
• an expander section (3) comprising a rotary expander (11) with a rotary expander element in which the in the evaporator section at least partly evaporated working fluid is expanded;
• and
• a generator section (5) comprising a rotary power generator (13) with a rotor,
• whereby the expander section (3), the liquid pump section (4) and the generator section (5) are rotably connected in such a manner that relative rotational speed ratios between the rotary expander element of the rotary expander (11), the impeller of the rotary liquid pump (7) and the rotor of the rotary power generator (13) are mechanically upheld,
• wherein
• a controlled portion (15) of the working fluid entering the rotary liquid pump (7) is allowed to pass from the liquid pump section (4) to the expander section (3) and/or the generator section (5) by means of a throttling device, which the drive shaft (8) by which the impeller of the rotary liquid pump (7) is driven is provided with,
• whereby the rotary expander (11) and/or rotary power generator (13) is cooled by the controlled portion (15) of the working fluid which passes from the liquid pump section (4) to the expander section (3) respectively the generator section (5).