Tank, liquid circulation system and operating method

1. A liquid circulation system comprising:

a rotor located within a tank,

an electric component accommodated within the tank,

a power unit comprising a stator having a plurality of coils, a control unit and an electric terminal box, the power unit is attached outside the tank, and

an exterior tank wall of the tank that is non-magnetic and that is located next to the rotor and to the stator between the rotor and the stator, the power unit is attached on the exterior tank wall,

wherein

the tank is configured as a sub-sea component,

the rotor faces the electric component so that there is no exterior tank wall between the rotor and the electric component,

an axis (R) of rotation of the rotor is in parallel with the exterior tank wall next to the rotor,

the rotor is configured to be rotated by the stator through the exterior tank wall by means of a varying electromagnetic field driven by the stator to circulate a liquid within the tank and a paddle portion of the rotor is configured to rotate around the axis (R) of rotation is distant from the exterior tank wall,

the coils of the stator are arranged along the axis (R) of rotation of the rotor so that the coils are arranged in a linear manner along a straight line, and

at least a driving portion of the rotor is of helical shape.

2. The liquid circulation system of claim 1 ,

wherein the electric component and the rotor are located in a common main tank volume.

3. The liquid circulation system of claim 1 ,

which is configured to be put into saltwater up to a depth of 1 km or 2 km or 3 km or 5 km.

4. The liquid circulation system of claim 1 ,

wherein the tank is filled with the liquid and the liquid is transformer oil.

5. The liquid circulation system of claim 1 ,

wherein the power unit is reversibly attachable to the exterior tank wall, and

wherein a distance between the paddle portion and the exterior tank wall next to the rotor is at least 1 mm and is at most 0.01 m.

6. The liquid circulation system of claim 1 ,

wherein the tank accommodates at least one of a transformer, a drive and a shunt reactor as the electric component, and

wherein the exterior tank wall is made of steel and has a thickness of between 0.5 cm and 3 cm inclusive.

7. The liquid circulation system of claim 1 ,

wherein ends of the rotor that bear the paddle portion are supported in a fixed manner so that the ends have a fixed location relative to the exterior tank wall next to the rotor.

8. The liquid circulation system of claim 1 ,

wherein a length of the paddle portion along the axis (R) of rotation is between 1.5 and 15 windings of the helix.

9. The liquid circulation system of claim 1 ,

wherein the rotor is of iron or an iron alloy,

wherein an extent of the rotor along the axis (R) of rotation is at least 0.2 m and at most 2 m, and

wherein a diameter of the rotor in a direction perpendicular to the axis (R) of rotation is at least 0.05 m and at most 0.5 m, the extent being larger than the diameter by at least a factor of 2.

10. The liquid circulation system of claim 1 ,

wherein the rotor comprises a winded flat bar configured to move the liquid, and

wherein the rotor is one single piece.

11. The liquid circulation system of claim 1 ,

wherein the stator is electrically driven by means of a directional T interchange, and

wherein at least some of the coils are connected in pairs in an anti-parallel manner.

12. The liquid circulation system of claim 1 ,

wherein the rotor is arranged in an upright manner next to the exterior tank wall so that the axis (R) of rotation is oriented vertically and so that the rotor is configured to transport the liquid from bottom to top along the exterior tank wall.

13. The liquid circulation system of claim 1 ,

wherein the tank comprises at least one of a duct and a guide next to the rotor and within the tank for leading the liquid.

14. The liquid circulation system of claim 1 ,

wherein the tank accommodates N of the rotors and N is a natural number ≥3, the N rotors are located at different locations inside the exterior tank wall,

wherein M of the stators are located outside the exterior tank wall, M is a natural number ≥2 and M<N, and

wherein there is a one-to-one assignment between the M stators and M of the rotors, and N−M of the rotors are not assigned to one of the stators.

15. A method to operate a liquid circulation system of claim 1 , the method comprising:

applying the stator onto the exterior tank wall next to the rotor,

powering the stator so that the stator drives the varying electromagnetic field,

rotating the rotor by means of the varying electromagnetic field driven in the touchless manner through the exterior tank wall so that the liquid is circulated within the tank.