ORC for transporting waste heat from a heat source into mechanical energy and cooling system making use of such an ORC

• US 10,612,423 B2
• Filed: 08/18/2016
• Issued: 04/07/2020
• Est. Priority Date: 09/08/2015
• Status: Active Grant

• Current Assignee: Atlas Copco Airpower Nv (Atlas Copco AB)
• Original Assignee: Atlas Copco Airpower Nv (Atlas Copco AB)
• Inventors: Ohman, Henrik
• Primary Examiner(s): Nguyen, Hoang M
• Application Number:
  US15/757,350
• Publication Number:
  US 20180252120A1
• Time in Patent Office: 1,328 Days
• Field of Search: 60649, 60671, 60646, 60657, 60661, 60666
• CPC Class Codes: F01K 11/00 Plants characterised by the engines being structurally combined with boilers or condensers
• CPC Class Codes: F01K 21/005 using mixtures of liquid and steam or evaporation of a liquid by expansion
• CPC Class Codes: F01K 25/04 the fluid being in different phases, e.g. foamed
• CPC Class Codes: F01K 25/08 using special vapours
• CPC Class Codes: F01K 25/14 using industrial or other waste gases
• CPC Class Codes: F01K 9/003 condenser cooling circuits

Abstract

An Organic Rankine Cycle (ORC) device and method for transforming heat from a heat source into mechanical energy. The ORC includes a closed circuit containing a two phase working fluid. The circuit comprises a liquid pump for circulating the working fluid consecutively through an evaporator which is configured to be placed in thermal contact with the heat source; through an expander for transforming the thermal energy of the working fluid into mechanical energy; and through a condenser which is in thermal contact with a cooling element. The expander is situated above the evaporator. The fluid outlet of the evaporator is connected to the fluid inlet of the expander by a raiser column which is filled with a mixture of liquid working fluid and of gaseous bubbles of the working fluid, which mixture is supplied to the expander.

Claims

1. An Organic Rankine Cycle (ORC) installation for transforming heat from a heat source into mechanical energy, the ORC installation comprising:

a closed circuit containing a two-phase working fluid, the closed circuit comprising a liquid pump for circulating the two-phase working fluid in the closed circuit consecutively through an evaporator which is configured to be placed in thermal contact with said heat source;

through an expander for transforming thermal energy of the two-phase working fluid into mechanical energy; and

through a condenser which is in thermal contact with a cooling element,

wherein the expander is physically located above the evaporator and a fluid outlet of the evaporator is connected to a fluid inlet of the expander by a raiser column which is filled with a mixture of liquid working fluid and of gaseous bubbles of the working fluid in a way such that the liquid working fluid flows into the evaporator to replace the gaseous bubbles of the working fluid produced in the evaporator, said mixture being supplied to the expander, and in that the raiser column extends with at least a part at a same level or above a level of the fluid inlet of the expander in such a way that a gravitational flow of the liquid working fluid is used to supply at least some of the working fluid from the raiser column to the expander,

wherein the condenser is primarily located at a lower level than the expander in such a way that a gravitational flow of the liquid working fluid is used to supply the working fluid from the expander to the condenser,

wherein the evaporator is primarily located at a lower level than the condenser in such a way that a gravitational flow of the liquid working fluid is used to supply the working fluid from the condenser to the evaporator, and

wherein the ORC installation is designed such that, in case the expander and/or the liquid pump are not operational, the ORC installation operates as a self circulating circuit, driven by thermal gravitational effects on the fluid.

2. The ORC installation according to claim 1, wherein a lowest part of the fluid inlet of the condenser is located lower than a lowest part of the rotative, active parts of the expander.

3. The ORC installation according to claim 1, wherein a lowest part of the fluid inlet of the evaporator is located lower than lowest part of the fluid outlet of the condenser.

4. The ORC installation according to claim 1, wherein the ORC installation is so designed that in at least some operating conditions the evaporator is completely filled with boiling working fluid and in that the raiser column is filled with a mixture of liquid working fluid and of gaseous bubbles of the working fluid, which mixture is supplied to the expander.

5. The ORC installation according to claim 4, wherein a capacity of the liquid pump is chosen such that said liquid pump is pumping more liquid than could be evaporated in the evaporator.

6. The ORC installation according to claim 1, wherein the ORC circuit is provided with a bypass bridging the inlet and the outlet of the liquid pump and comprising a valve with a control for keeping the valve closed during normal operating conditions of the ORC installation and opening the valve in case the liquid pump would not be operational due to failure or other reasons.

7. The ORC installation according to claim 1, wherein the ORC circuit is provided with a bypass bridging the inlet and the outlet of the expander and comprising a valve with a control for keeping the valve closed during normal operating conditions of the ORC installation and opening the valve in case the expander would not be operational due to failure or other reasons.

8. The ORC installation according to claim 4, wherein the control of the valves is such that in case the expander and/or the liquid pump fails, both valves are opened.

9. The ORC installation according to claim 1, wherein the expander is of any kind suitable to accept a mixture of liquid and gaseous working fluid.

10. The ORC installation according to claim 1, wherein the expander is a volumetric expander.

11. The ORC installation according to claim 1, wherein the expander is a screw expander.

12. The ORC installation according to claim 1, wherein a working fluid is used which comprises a lubricant or which acts as a lubricant.

13. The ORC installation according to claim 1, wherein a working fluid is used of which the boiling temperature is lower than 90°

C.

14. The ORC installation according to claim 7, wherein a location where the bypass branches to the ORC circuit at the inlet side of the expander is situated at a higher level than the condenser.

15. A cooling system for cooling a source of waste heat, wherein the cooling system comprises an ORC installation according to claim 1 as only means for cooling of the heat source without the need for any additional external cooling, also in conditions of non operation of the expander and/or of non-operation of the liquid pump.

16. The ORC installation according to claim 13, wherein a working fluid is used of which the boiling temperature is lower than 60°

C.

17. An Organic Rankine Cycle (ORC) installation for transforming heat from a heat source into mechanical energy, the ORC installation comprising:

a closed circuit containing a two-phase working fluid, the closed circuit comprising a liquid pump for circulating the two-phase working fluid in the closed circuit consecutively through an evaporator which is configured to be placed in thermal contact with said heat source;

through an expander for transforming thermal energy of the two-phase working fluid into mechanical energy; and

through a condenser which is in thermal contact with a cooling element,

wherein a fluid outlet of the evaporator is connected to a fluid inlet of the expander by a raiser column which is filled with a mixture of liquid working fluid and of gaseous bubbles of the working fluid, and where in the installation is configured so that the liquid working fluid flows into the evaporator to replace the gaseous bubbles of the working fluid produced in the evaporator, said mixture being supplied to the expander, and in that the raiser column extends with at least a part at a same level or above a level of the fluid inlet of the expander in such a way that a gravitational flow of the liquid working fluid is used to supply at least some of the working fluid from the raiser column to the expander,

wherein the condenser is primarily located at a lower level than the expander in such a way that a gravitational flow of the liquid working fluid is used to supply the working fluid from the expander to the condenser,

wherein the evaporator is primarily located at a lower level than the condenser in such a way that a gravitational flow of the liquid working fluid is used to supply the working fluid from the condenser to the evaporator, and

wherein the ORC installation is designed such that, in case the expander and/or the liquid pump are not operational, the ORC installation operates as a self circulating circuit, driven by thermal gravitational effects on the fluid.