Dual pressure geothermal system

• US 6,735,948 B1
• Filed: 12/16/2002
• Issued: 05/18/2004
• Est. Priority Date: 12/16/2002
• Status: Expired due to Fees

• Current Assignee: Kalina Power Limited
• Original Assignee: Icalox Incorporated
• Inventors: Kalina, Alexander I.
• Primary Examiner(s): Richter, Sheldon J.
• Application Number:
  US10/320,345
• Time in Patent Office: 519 Days
• Field of Search: 606/49, 606/51, 606/53, 606/71
• US Class Current: 60/649
• CPC Class Codes: F01K 25/065 with an absorption fluid remaining at least partly in the liquid state, e.g. water for ammonia F01K5/00 takes precedence

Abstract

a new thermodynamic cycle is disclosed for converting energy from a low temperature stream from an external source into useable energy using a working fluid comprising of a mixture of a low boiling component and a higher boiling component and including a higher pressure circuit and a lower pressure circuit. The cycle is designed to improve the efficiency of the energy extraction process by mixing the liquid stream from the high pressure circuit with the spent low pressure circuit stream forming a lean system that can be condensed at a low pressure. The new thermodynamic process and the system for accomplishing it are especially well-suited for streams from low-temperature geothermal sources.

Claims

1. A method for implementing a thermodynamic cycle comprising the steps of:

transforming thermal energy from a fully vaporized higher pressure stream into a usable energy form to product produce a spent higher pressure stream;

transforming thermal energy from a vaporized lower pressure stream into a usable energy form to produce a spent lower pressure stream;

heating a higher pressure liquid stream with a portion of a spent higher pressure stream to form a heated higher pressure stream and a first partially condensed spent higher pressure stream;

heating a lower pressure stream with a remaining portion of the spent higher pressure stream to form a heated lower pressure stream and a second partially condensed spent higher pressure stream;

heating the heated higher pressure liquid stream with a portion of an external heat source stream to form a hotter higher pressure stream and a first spent external heat source stream;

heating the heated lower pressure stream with a remaining portion of the external hear source stream to form a vaporized lower pressure stream and a second spent external heat source stream;

heating the hotter higher pressure stream with the external heat source stream to form the fully vaporized higher pressure stream;

separating the partially condensed spent higher pressure streams into a spent higher pressure liquid stream and a spent higher pressure vapor stream;

mixing the spent higher pressure liquid stream with the spent lower pressure stream at the pressure of the spent lower pressure stream to form a combined spent lower pressure stream;

condensing the combined spent lower pressure stream with an external cooling stream to form a condensed spent lower pressure stream;

mixing the condensed spent lower pressure stream with the spent higher pressure vapor stream to form a combined partially condensed spent higher pressure stream at the pressure of the spent higher pressure vapor stream;

condensing the combined partially condensed spent high pressure stream to form a fully condensed liquid stream; and

forming the higher pressure stream and the lower pressure stream from a fully condensed liquid stream.

2. The method of claim 1, wherein the vaporized lower pressure stream is fully vaporized and the composition of the fully condense liquid stream is sufficient to fully vaporize the heated lower pressure stream.

3. The method of claim 1, further comprising the step of:

separating the vaporized lower pressure stream into a fully vaporized lower pressure stream and a liquid lower pressure stream;

mixing the liquid lower pressure stream with the remaining portion of the spent higher pressure stream prior to the lower pressure stream heating step; and

wherein the lower pressure transforming step uses the fully vaporized lower pressure stream.

4. The method of claim 1, wherein the spent higher pressure liquid stream has a leaner composition than the composition of the fully condensed liquid stream.

5. A method for implementing a thermodynamic cycle comprising the steps of:

forming a higher pressure working fluid stream and a lower pressure working fluid stream from a fully condensed working fluid stream;

heating the higher pressure working fluid stream with a portion of a spent higher pressure working fluid stream to form a heated higher pressure working fluid stream and a first partially condensed spent higher pressure working fluid stream;

heating the heated higher pressure working fluid stream with a portion of a partially cooled external source stream to form a hotter higher pressure working fluid stream and a first spent external source stream;

vaporizing the hotter higher pressure working fluid stream with an external source stream to form a fully vaporized higher pressure working fluid stream and the partially cooled external source stream;

transforming thermal energy from the fully vaporized higher pressure working fluid stream into a usable energy form to produce a spent higher pressure working fluid stream;

heating the lower pressure working fluid stream with a remaining portion of the spent higher pressure working fluid stream to form a heated lower pressure working fluid stream and a second partially condensed spent higher pressure working fluid stream;

heating the heated lower pressure working fluid stream with a remaining portion of the partially cooled external source stream to form a vaporized lower pressure working fluid stream and a second spent external source stream;

transforming thermal energy from the vaporized lower pressure working fluid stream into a usable energy form to produce a spent lower pressure working fluid stream;

separating the first and second partially condensed, spent higher pressure working fluid a streams into a spent higher pressure liquid working fluid stream and a higher pressure vapor working fluid stream;

mixing the spent lower pressure working fluid stream with the spent higher pressure liquid working fluid stream at the lower pressure to form a combined spent lower pressure working fluid stream;

cooling the combined spent lower pressure working fluid stream with an external cooling stream to form a condensed lower pressure working fluid stream;

cooling the condensed lower pressure working fluid stream and the spent higher pressure vapor working fluid stream at a pressure of the spent higher pressure vapor working fluid stream with a second external cooling stream to form the fully condensed working fluid stream.

6. The method of claim 5, further comprising the step of:

separating the vaporized lower pressure working fluid stream into a fully vaporized lower pressure working fluid stream and a liquid lower pressure working fluid stream;

mixing the liquid lower pressure working fluid stream with the remaining portion of the spent higher pressure working fluid stream prior to the lower pressure working fluid stream heating step; and

wherein the lower pressure transforming step uses the fully vaporized lower pressure working fluid stream.

7. The method of claim 5, wherein the vaporized lower pressure working fluid stream is fully vaporized.

8. The method of claim 5, wherein the spent higher pressure liquid working fluid stream has a leaner composition than the composition of the fully condensed working fluid stream.

9. An apparatus for implementing a thermodynamic cycle comprising:

first means for expanding a fully vaporized higher pressure stream, transferring its energy into usable form and producing a higher pressure spent stream;

second means for expanding a fully vaporized lower pressure stream, transferring its energy into usable form and producing a lower pressure spent stream;

a first heat exchanger adapted to condense a combined lower pressure spent stream with an external coolant stream to form a condensed combined lower pressure spent stream;

a first pump adapted to increase a pressure of the condensed combined lower pressure spent stream to form an increased pressure, condensed combined lower pressure spent stream;

a first stream mixer adapted to combine the increased pressure, condensed combined lower pressure spent stream and a vapor higher pressures spent stream to form a partially condensed stream;

a second heat exchanger adapted to condense the partially condensed stream with an external coolant stream to form a fully condensed liquid stream;

a first stream splitter adapted to form first and second portions of the fully condensed liquid stream;

a second pump adapted to increase a pressure the first portion of the fully condensed liquid stream to form a higher pressure liquid stream;

a third pump adapted to increase a pressure the second portion of the fully condensed liquid stream to form a lower pressure liquid stream;

a third heat exchanger adapted to heat the higher pressure liquid stream with a first portion of a higher pressure spent stream to form a heated higher pressure liquid stream and a first partially condensed higher pressure spent stream;

a fourth heat exchanger adapted to heat the lower pressure liquid stream with a remaining portion of the higher pressure spent stream to form a heated lower pressure liquid stream and a second partially condensed higher pressure spent stream;

a fifth heat exchanger adapted to heat the heated higher pressure liquid stream with a first portion of a partially cooled external heat source stream to form a hotter higher pressure liquid stream and a first spent external heat source stream;

a sixth heat exchanger adapted to heat the heated lower pressure liquid stream with a remaining portion of the partially cooled external heat source stream to form a vaporized lower pressure stream and a second spent external heat source stream;

a seventh heat exchanger adapted to vaporize the hotter higher pressure liquid stream with an external heat source stream mixer to form the fully vaporized higher pressure stream and the partially cooled external heat source stream;

a second stream splitter adapted to form the first and second portions of the higher pressure spent stream;

a third stream splitter adapted to form the first and second portions of the cooled external heat source stream;

a second stream mixer adapted to combine the first and second partially condensed higher pressure spent stream to form a combined partially condensed higher pressure spent stream;

a gravity separator adapted to separate combined partially condensed higher pressure spent stream into a lean liquid stream and a rich vapor stream;

a throttle valve adapted to change the pressure of the lean liquid stream to a pressure of the lower pressure spent stream; and

a third stream mixer adapted to combine the pressure adjusted lean liquid stream with the lower pressure spent stream,

where the apparatus results in an improved efficiency.