# US 8,769,952 B2 · Oil recovery from an evaporator of an organic rankine cycle (ORC) system

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- Number: US 8,769,952 B2
- Document ID: US8769952B2
- Status: Granted
- Kind: B2
- Application number: 12/670,764
- Filed: 2007-07-27
- Published: 2010-07-29
- Granted: 2014-07-08
- Earliest claimed: 2007-07-27
- Assignees: United Technologies Corporation
- Applicants: Frederick J. Cogswell; Ulf J. Jonsson; Bruce P. Biederman; Peter S. Matteson; Michael D. Arner
- Inventors: Frederick J. Cogswell; Ulf J. Jonsson; Bruce P. Biederman; Peter S. Matteson; Michael D. Arner
- Web page: https://patentgrep.com/patent/US8769952B2

## CPC

- F01K 25/10: the vapours being cold, e.g. ammonia, carbon dioxide, ether
- F01D 25/18: Lubricating arrangements (of machines or engines in general F01M)
- F01K: STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES (gas-turbine or jet-propulsion plants F02; nuclear power plants, engine arrangements therein G21D)
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)

## Abstract

A method and system for recovering oil is used in an organic rankine cycle (ORC) system to recover oil from an evaporator of the ORC system and return the oil to an oil sump. The ORC system includes an evaporator, a turbine, a condenser and a pump, and is configured to circulate a refrigerant through the ORC system. The oil recovery system includes a recovery line configured to remove a mixture of oil and refrigerant from the evaporator. The mixture of oil and refrigerant passes through a heat exchanger in order to vaporize liquid refrigerant in the mixture and produce a mixture of oil and vaporized refrigerant. A delivery line is configured to deliver the mixture of oil and vaporized refrigerant to the turbine, at which point the oil may be separated from the vaporized refrigerant and recycled back to the oil sump.

## Claims

### Claim 1

An organic rankine cycle (ORC) system for generating power, the ORC system comprising:
a condenser configured to condense a vaporized refrigerant;
a pump configured to increase a pressure of the condensed refrigerant;
an evaporator configured to receive the condensed refrigerant and vaporize the refrigerant;
a turbine configured to receive the vaporized refrigerant and generate power;
an oil sump for storing oil used to operate the turbine;
a heat exchanger located downstream of the evaporator and configured to receive a mixture of oil and refrigerant from the evaporator, and vaporize liquid refrigerant in the mixture such that the oil is separable from the refrigerant and recoverable by the oil sump;
a separator configured to separate the oil and the vaporized refrigerant from the mixture, wherein the separator is a discharge housing of the turbine; and
an eductor system for delivering oil from the separator to the oil sump.

### Claim 2 (depends on 1)

The ORC system of claim 1 wherein a saturated vapor refrigerant from the evaporator passes through the heat exchanger to vaporize the refrigerant in the mixture of oil and refrigerant.

### Claim 3 (depends on 1)

The ORC system of claim 1 wherein the ORC system further comprises a delivery line and the turbine comprises a vent, and wherein the delivery line delivers the mixture of oil and vaporized refrigerant to the discharge housing of the turbine, and wherein the discharge housing separates the oil and the vaporized refrigerant such that the oil collects in a bottom of the discharge housing and the vaporized refrigerant exits the turbine through the vent.

### Claim 4 (depends on 1)

The ORC system of claim 1 wherein the eductor system comprises:
a first eductor configured to extract liquid from the separator; and
an eductor line for delivering refrigerant to the first eductor to drive the first eductor.

### Claim 5

A method of recovering oil in an organic rankine cycle (ORC) system having an evaporator, a turbine, an oil sump, and a condenser, the method comprising:
removing a mixture of oil and refrigerant from the evaporator;
increasing a temperature of the mixture using a heat exchanger such that liquid refrigerant in the mixture vaporizes;
separating the oil and the vaporized refrigerant after the mixture has exited the heat exchanger, wherein a discharge housing of the turbine separates the oil and vaporized refrigerant; and
delivering the oil to the oil sump.

### Claim 6 (depends on 5)

The method of claim 5 further comprising:
delivering the vaporized refrigerant to the condenser, after separating the oil and the vaporized refrigerant.

### Claim 7 (depends on 5)

The method of claim 5 wherein delivering the oil to the oil sump comprises:
removing the oil from the discharge housing an eductor system.

### Claim 8 (depends on 5)

The method of claim 5 further comprising:
restricting a flow of the mixture of oil and refrigerant using an orifice, prior to increasing a temperature of the mixture.

### Claim 9 (depends on 5)

The method of claim 5 wherein the discharge housing separates the oil and the vaporized refrigerant such that the oil collects in a bottom of the discharge housing and the vaporized refrigerant exits the turbine through a vent in the turbine.

### Claim 10 (depends on 5)

The method of claim 5 wherein removing the mixture of oil and refrigerant from the evaporator is performed by a scavenger port connected to the evaporator.

### Claim 11 (depends on 5)

The method of claim 5 wherein removing the mixture of oil and refrigerant from the evaporator is performed by an oil skimmer inside the evaporator.