Lubrication of expansion machines

1. A thermodynamic circuit process device, comprising:

a working medium with a lubricant additive;

an expansion machine for converting enthalpy in the working medium with the lubricant additive into mechanical energy;

a multi-stage pressure-increasing pump for a step-by-step pressurization of the working medium with the lubricant additive;

a means for branching off a part of the working medium with the lubricant additive between two stages of the multi-stage pressure-increasing pump at a suited pressure level; and

a means for feeding the branched off part of the working medium with the lubricant additive at the suited pressure level to one or more bearing points of the expansion machine, wherein the one or more bearing points receive the working medium with the lubricant additive at the suited pressure level.

2. The thermodynamic circuit process device according to claim 1 , wherein said multi-stage pump is a multi-stage centrifugal pump.

3. The thermodynamic circuit process device according to claim 2 , wherein said means for branching off a part of the working medium with the lubricant additive comprises a bore between two stages of the multi-stage pump.

4. The thermodynamic circuit process device according to claim 1 , wherein said means for feeding the branched off part of the working medium with the lubricant additive at the suited pressure level to one or a plurality of bearing points of the expansion machine comprises one or a plurality of pipelines.

5. The thermodynamic circuit process device according to claim 2 , wherein the multi-stage pump includes a plurality of impellers, and said means for branching off a part of the working medium with the lubricant additive at the suited pressure level is disposed in a conveying direction of the multi-stage pump between two directly adjacent impellers.

6. The thermodynamic circuit process device according to claim 1 , furthermore comprising:

a means for discharging said working medium with said lubricant additive from said bearing point or points, wherein said means for discharging the working medium is in fluid communication with an outlet of the expansion machine.

7. The thermodynamic circuit process device according to claim 1 , in which the thermodynamic circuit process device is an Organic Rankine Cycle device, and/or in which the expansion machine is selected from the group consisting of a piston expansion machine, a screw expansion machine, a scroll expander, a vane machine, and a roots expander.

8. The thermodynamic circuit process device according to claim 1 , wherein said working medium is provided in a form of an organic working medium, said working medium comprising a fluorinated working medium, and/or said lubricant comprising a refrigerant oil, wherein a lubricant proportion of said working medium is between 0.1 and 10 weight percent.

9. A steam power station, comprising the device according to claim 1 .

10. A method for lubricating an expansion machine in a thermodynamic circuit process device, wherein said thermodynamic circuit process device comprises an expansion machine, a multi-stage pressure-increasing pump and a working medium with a lubricant additive, and wherein said method comprises the steps of:

step-by-step pressurizing the working medium with the lubricant additive with the multi-stage pressure-increasing pump;

branching off a part of said working medium with the lubricant additive between two stages of the multi-stage pressure-increasing pump at a suited pressure level; and

feeding the branched off part of the working medium with the lubricant additive at the suited pressure level to one or more bearing points of the expansion machine for lubricating the one or more bearing points, wherein the one or more bearing points receive the working medium with the lubricant additive at the suited pressure level.

11. The method according to claim 10 , wherein the branching off of a part of the working medium with the lubricant additive via a bore is effected between the two stages of the multi-stage pump.

12. The method according to claim 10 , wherein the feeding of the branched off part of the working medium with the lubricant additive at the suited pressure level to one or more bearing points of the expansion machine is effected via one or a plurality of pipelines.

13. The method according to claim 10 , wherein the multi-stage pump includes a plurality of impellers, and the branching off of a part of the working medium with the lubricant additive at the suited pressure level is effected in a conveying direction of the multi-stage pump between two directly adjacent impellers.

14. The method according to claim 10 , further comprising the step of:

discharging said working medium with said lubricant additive from the one or more bearing points, wherein the discharging of said working medium is effected in fluid communication with an outlet of the expansion machine.

15. The method according to claim 10 , wherein said working medium comprises a fluorinated working medium, and/or said lubricant comprises refrigerant oil, wherein a lubricant proportion of said working medium is between 0.1 and 10 weight percent.

16. The method according to claim 10 , wherein the multi-stage pump is a multi-stage centrifugal pump.

17. The thermodynamic circuit process device according to claim 1 , wherein the expansion machine is selected from a group consisting of a piston expansion machine, a scroll expander, a vane machine and a roots expander.

18. The thermodynamic circuit process device according to claim 17 , further comprising a means for discharging said working medium with said lubricant additive from said one or more bearing points, wherein said means for discharging the working medium is in fluid communication with an outlet of the expansion machine.