Microturbine power generating system

• US 6,198,174 B1
• Filed: 01/28/2000
• Issued: 03/06/2001
• Est. Priority Date: 12/20/1997
• Status: Expired due to Fees

• Current Assignee: Hybrid Power Generation Systems, LLC
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: OʼBrien, Patrick Lee, Emerson, Terrence, Nims, Robert A.
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/493,644
• Time in Patent Office: 403 Days
• Field of Search: 290/52, 290/40.A, 290/40.B, 290/40.C, 290/40.D, 60/395.11, 602/62, 60/395, 60/395.12
• US Class Current: 290/52
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F02C 3/05 the compressor and the turbine being of the radial flow type
• CPC Class Codes: F02C 7/08 Heating air supply before combustion, e.g. by exhaust gases
• CPC Class Codes: F05D 2240/60 Shafts
• CPC Class Codes: F05D 2250/311 the axes being in line
• CPC Class Codes: F05D 2250/82 Micromachines
• CPC Class Codes: F05D 2250/84 Nanomachines
• CPC Class Codes: H02K 7/1823 structurally associated with turbines or similar engines

Abstract

A microturbine power generation system includes an electrical generator, a turbine and a compressor intermediate the generator and the turbine. The turbine, compressor and electrical generator are secured together by a tieshaft. The tieshaft is prestressed such that faces of the turbine, electrical generator and compressor maintain contact during high-speed, high-temperature operation of the system.

Claims

1. A microturbine power generating system, comprising:

a turbine for converting gaseous heat energy into mechanical energy;

a power converter for converting the mechanical energy produced by the turbine into electrical energy, the power converter having a rotating portion and a non-rotating portion; and

a single tieshaft having a diameter of less than about one-half inch, the tieshaft connecting the turbine and the rotating portion of the power converter, wherein, during operation of the microturbine power generating system, said tieshaft, turbine and rotating portion of the power converter rotate in unison at speeds of at least about 60,000 rpm.

2. The microturbine power generating system of claim 1 further comprising:

a combustor for producing gaseous heat energy by igniting an air and fuel mixture;

a fuel supply for supplying fuel to the combustor; and

a compressor for compressing intake air and supplying the compressed air to the combustor, the compressor being coupled to the tieshaft and, during operation of the microturbine power generating system, rotating in unison with said tieshaft, turbine and rotating portion of the power converter.

3. The microturbine power generating system of claim 2 wherein the compressor is positioned between the turbine and the power converter.

4. The microturbine power generating system of claim 2, further comprising a recuperator having thermally coupled first and second pathways, the first pathway having an entrance for receiving high temperature compressed air front the compressor and an exit for supplying higher temperature compressed air to the combustor, the second pathway having an entrance for receiving high temperature exhaust air from the turbine and an exit for releasing lower temperature exhaust air.

5. The microturbine power generating system of claim 2, wherein the power converter comprises an electric generator, the electrical generator producing alternating electric current during operation of the microturbine power generating system.

6. The microturbine power generating system of claim 5, wherein the power converter further comprises:

a rectifier, coupled to the electrical generator, for the rectifying alternating electric current produced by the generator; and

an inverter, coupled to the rectifier, for accepting direct current from the rectifier and converting the direct current into alternating current of a preselected frequency.

7. The microturbine power generating system of claim 2, wherein the rotating portion of the power converter is a permanent magnet and the non-rotating portion of the power converter is a stator, said permanent magnet being positioned rotatably within said stator and rotating relative thereto during operation of the microturbine power generating system.

8. The microturbine power generating system of claim 2, wherein the fuel is selected from the group consisting of diesel, flare gas, off gas, gasoline, naphtha, propane, JP-8, methane, and natural gas.

9. The microturbine power generating system of claim 2, further comprising a support means for supporting the turbine, the power converter, the compressor, the recuperator and the combustor.

10. The microturbine power generating system of claim 9, wherein the support means comprises a single enclosure having an air inlet and an exhaust outlet, the enclosure surrounding the turbine, the power converter, the compressor, the recuperator and the combustor.

11. The microturbine power generating system of claim 2, wherein the combustor includes a catalyst.

12. The microturbine power generating system of claim 2, further comprising:

an exhaust passage downstream from the turbine; and

an air intake passage upstream from the compressor, at least a portion of said air intake passage being orthogonal to said exhaust passage.

13. The microturbine power generating system of claim 3, further comprising:

an exhaust passage downstream from the turbine; and

an air intake passage upstream from the compressor, at least a portion of said air intake passage being orthogonal to said exhaust passage.

14. The microturbine power generating system of claim 7 wherein the stator includes a plurality of stator windings and a stator coolant passageway having an exit and an entrance, said stator coolant passageway being thermally coupled to said stator windings, said entrance receiving relatively cool stator cooling fluid and said exit discharging relatively warm stator cooling fluid during operation of the microturbine power generating system.

15. The microturbine power generating system of claim 3, further comprising:

inboard and outboard foil journal bearings concentric with the tieshaft;

a foil thrust bearing concentric with the tieshaft and adjacent the rotating portion of the power converter; and

a bearing coolant passageway having an exit and an entrance, said bearing coolant passageway flowing over said journal bearings and said thrust bearing, wherein, during operation of the microturbine power generating system, said journal bearings support the turbine, compressor and rotating portion of the power converter in a radial direction, said thrust bearing supports the turbine, compressor and rotating portion of the power converter in an axial direction, said entrance receives relatively cool bearing cooling fluid, and said exit discharges relatively warm bearing cooling fluid.

16. The microturbine power generating system of claim 14, further comprising:

inboard and outboard foil journal bearings concentric with the tieshaft;

a foil thrust bearing concentric with the tieshaft and adjacent the rotating portion of the power converter; and

a bearing coolant passageway having an exit and an entrance, said bearing coolant passageway flowing over said journal bearings and said thrust bearing, wherein, during operation of the microturbine power generating system, said journal bearings support the turbine, compressor and rotating portion of the power converter in a radial direction, said thrust bearing supports the turbine, compressor and rotating portion of the power converter in an axial direction, said entrance receives relatively cool bearing cooling fluid, and said exit discharges relatively warm bearing cooling fluid.

17. A method of generating power from high temperature gases comprising the steps of:

providing a tieshaft having a yield strength, and putting said tieshaft in tension to a predetermined percentage of said yield strength;

coupling a turbine and a rotating portion of a power converter on the single tieshaft, the turbine, the rotating portion of the power converter, and the tieshaft being rotatable relative to a fixed portion of the power converter;

expanding the high temperature gases through the turbine, thereby causing the turbine, the rotating portion of the power converter and the tieshaft to rotate at speeds of at least about 60,000 rpm, whereby an electrical current is induced in the power converter.

18. The method of generating power from high temperature gases of claim 17, further comprising the steps of:

compressing intake air;

mixing fuel with the compressed intake air in a combustor;

combusting the mixture to produce high temperature gases comprising combustion products; and

supplying the combustion products to the turbine.

19. The method of generating power from high temperature gases of claim 18, further comprising the step of combusting the fuel and air to produce the combustion products at least in part in the presence of a catalyst.

20. The method of claim 18, further comprising the steps of:

after expanding the high temperature gases through the turbine, supplying at least a portion of the heat in the high temperature gases to the intake air.

21. The method of claim 17, wherein the rotating portion of the power converter is a permanent magnet and the fixed portion is a stator, the rotation of the magnet inducing variable frequency alternating current electrical energy in said stator.

22. The method of claim 21, further comprising the step of rectifying the variable frequency alternating current electrical energy to produce direct current electrical energy.

23. The method of claim 22, further comprising the step of inverting the direct current electrical energy to produce an alternating current electrical energy having a predetermined frequency.