Method for retrofitting a double flow steam turbine

1. A method for retrofitting a double flow steam turbine, the double flow steam turbine having:

an outer casing;

blade carriers with stator blades;

an inner casing with inlet belt; and

a double flow rotor with rotor blades, wherein the method comprises:

opening the outer casing;

removing the blade carriers and the stator blades;

removing the inner casing with inlet belt;

removing the double flow rotor and the rotor blades;

providing and installing a new single flow rotor and new rotor blades different from the rotor blades connected to the double flow rotor;

providing and installing balancers connected to the single flow rotor, to balance the axial thrust;

providing and installing new stator blade carriers and new stator blades different from the stator blades associated to the double flow rotor;

providing and installing a new inner casing with inlet belt;

providing and installing at least a passage between the inner casing and the outer casing; and

closing the outer casing.

2. The method according to claim 1 , wherein the outer casing used with the single flow rotor is the same outer casing provided with the double flow rotor.

3. The method according to claim 1 , wherein the double flow steam turbine is also provided with extraction chambers connected to heater extraction ports of the outer casing via ducts, the method further comprising:

removing the extraction chambers and ducts;

providing new extraction chambers; and

providing new ducts connecting the new extraction chambers to the heater extraction ports of the outer casing.

4. The method according to claim 3 , wherein the new extraction chambers are placed at opposite axial sides of the inlet belt arranged to supply steam to the single flow rotor.

5. The method according to claim 3 , further comprising providing channels connecting the new extraction chambers together.

6. The method according to claim 5 , wherein the channels overcome the inlet belt without requiring a reduction of its cross section.

7. The method according to claim 1 , wherein the balancers comprise balance pistons.

8. The method according to claim 1 , wherein the balancers comprise a single flow steam turbine reciprocally connected to the rotor and further having opposite flow directions to that of the retrofitted double flow steam turbine.

9. The method according to claim 8 , wherein the mutually associated single flow steam turbines have a common inlet pipe, and

wherein the single flow steam turbine and the retrofitted double flow steam turbine have a common inlet pipe.