U.S. patent application number 10/012972 was filed with the patent office on 2002-08-15 for air bearing articulated shaft and floating module configuration for a small rotary compressor.
Invention is credited to Swinton, Michael.
Application Number | 20020110450 10/012972 |
Document ID | / |
Family ID | 26684258 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020110450 |
Kind Code |
A1 |
Swinton, Michael |
August 15, 2002 |
Air bearing articulated shaft and floating module configuration for
a small rotary compressor
Abstract
An apparatus for mounting a plurality of rotary compressors with
minimal mechanical tolerances, wherein each of the compressors
imparts axial forces on the structures with which they are mounted.
The mounting apparatus includes an articulated shaft that
rotationally couples and axially decouples the impeller wheels of
the rotary compressors. The articulated shaft interoperates with
compressors configured in a back-to-back configuration and, in
addition, may be coupled to a motor. The articulated shaft and the
impeller wheels may be supported by air bearings. It is emphasized
that this abstract is provided to comply with the rules requiring
an abstract which will allow a searcher or other reader to quickly
ascertain the subject matter of the technical disclosure. It is
submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims.
Inventors: |
Swinton, Michael;
(Fallbrook, CA) |
Correspondence
Address: |
Paul Backofen
IRELL & MANELLA LLP
Suite 900
1800 Avenue Of the Stars
Los Angeles
CA
90067
US
|
Family ID: |
26684258 |
Appl. No.: |
10/012972 |
Filed: |
November 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60245835 |
Nov 3, 2000 |
|
|
|
Current U.S.
Class: |
415/143 |
Current CPC
Class: |
F01D 5/026 20130101;
F01D 15/10 20130101; F04D 29/057 20130101; F04D 23/008 20130101;
F04D 29/053 20130101; F01D 25/166 20130101; F01D 25/22
20130101 |
Class at
Publication: |
415/143 |
International
Class: |
F01D 013/00 |
Claims
What is claimed is:
1. An apparatus comprising: a plurality of rotary compressors, each
compressor having at least one impeller wheel; and an articulated
shaft that rotationally couples and axially decouples at least one
impeller wheel from each of said plurality of rotary
compressors.
2. The apparatus of claim 1 wherein said plurality of rotary
compressors are mounted in back-to-back orientation.
3. The apparatus of claim 2 further comprising a motor coupled to
said articulated shaft.
4. The apparatus of claim 1 wherein a splined coupling connects at
least two segments of said articulated shaft.
5. The apparatus of claim 3 wherein a splined coupling connects
said articulated shaft with at least one shaft of said motor.
6. The apparatus of claim 1 wherein said articulated shaft
comprises at least three independent pieces.
7. The apparatus of claim 1 further comprising: an air bearing
supporting each of said impeller wheels.
8. The apparatus of claim 1 further comprising: at least one foil
thrust air bearing supporting at least one of said impeller
wheels.
9. The apparatus of claim 8 wherein said foil thrust bearing
further comprises: an underspring member mounted between a thrust
bearing surface and a compliant foil member.
10. The apparatus of claim 1 further comprising: a radial air
bearing supporting the articulated shaft.
11. The apparatus of claim 10 further comprising: a motor shaft;
and a coupling on the inside diameter of said radial air bearing
that engages a complimentary coupling on said motor shaft and
connects said articulated shaft to said motor shaft.
12. The apparatus of claim 1 further comprising: a plurality of
articulated shafts that rotationally couple and axially decouple at
least two back-to-back mounted rotary compressor impeller
wheels.
13. The apparatus of claim 12 further comprising: radial air
bearings supporting said articulated shafts; and air bearings
supporting said impeller wheels.
14. The apparatus of claim 12 wherein each of said rotary
compressors comprises one stage of a multi-stage compression
system.
15. A system comprising: a plurality of rotary compressors, each
having at least one impeller wheel; and a multi-piece shaft that
rotationally couples an impeller wheel from each of said
compressors and permits relative axial movement of said impeller
wheels.
16. The system of claim 15 further comprising: splined couplings
connecting a plurality of segments of said multi-piece shaft.
17. The system of claim 16 further comprising: radial air bearings
supporting said multi-piece shaft; and foil thrust air bearings
supporting said impeller wheels.
18. The system of claim 15 wherein said system is a device that
generates electricity.
19. The system of claim 15 wherein said system is an integrated
turbogenerator.
20. A method for rotationally driving a compound machine comprising
the steps of: rotationally coupling two or more rotating elements
of the compound machine to permit relative axial translation
between said rotating elements; and rotationally coupling said
rotating elements to a driving shaft of the compound machine.
21. The method of claim 20 wherein said rotating elements are
impeller wheels of rotary compressors.
22. The method of claim 20 wherein said step of rotationally
coupling two or more rotating elements of the compound machine
comprises coupling said elements with an articulated shaft.
23. The method of claim 22 further comprising coupling said
articulated shaft to a motor.
24. The method of claim 22 further comprising connecting at least
two segments of said articulated shaft through a splined
coupling.
25. The method of claim 22 further comprising connecting said
articulated shaft with a motor shaft via a splined coupling.
26. The method of claim 20 wherein said step of rotationally
coupling two or more rotating elements of the compound machine
comprises coupling said at least two rotating connectors through an
articulated connector.
27. The method of claim 21 further comprising mounting said rotary
compressors in back-to-back orientation.
28. The method of claim 27 further comprising supporting said
impeller wheels with an air bearing.
29. The method of claim 21 further comprising supporting said
impeller wheels with a foil thrust air bearing.
30. The method of claim 29 further comprising mounting an
underspring member between a thrust bearing surface and an aerofoil
portion of said foil thrust bearing.
31. The method of claim 22 further comprising supporting said
articulated shaft by a radial air bearing.
32. The method of claim 31 further comprising connecting said
articulated shaft to a motor shaft by engaging a coupling on the
inside diameter of said radial air bearing with a complimentary
coupling on said motor shaft.
33. The method of claim 20 wherein a the step of rotationally
coupling two or more rotating elements of the compound machine
comprises coupling at least two pairs of impeller wheels from
back-to-back mounted rotary compressors using a plurality of
articulated shafts.
34. The method of claim 22 further comprising the steps of:
supporting said articulated shaft by radial air bearings; and
supporting impeller wheels from a plurality of rotary compressors
on air bearings.
35. The method of claim 34 wherein each of said rotary compressors
comprises one stage of a multi-stage compression system.
36. The method of claim 21 further comprising mounting said rotary
compressors within a device that generates electricity.
37. The method of claim 21 further comprising mounting said rotary
compressors for use with a turbogenerator.
38. A turbogenerator comprising: a plurality of rotary compressors;
and means for rotationally coupling and axially decoupling at least
one impeller wheel from each of said plurality of rotary
compressors.
39. The turbogenerator of claim 36 wherein said means for
rotationally coupling also couples said impeller wheels to a motor
shaft.
40. The turbogenerator of claim 36 further comprising: means for
mounting said impeller wheels.
41. The turbogenerator of claim 36 further comprising: means for
supporting said means for rotationally coupling.
42. The turbogenerator of claim 36 wherein each of said rotary
compressors comprises one stage of a multi-stage compression
system.
43. An apparatus comprising: a rotating shaft; a first rotating
element; a first coupling rotationally securing the first rotating
element to the rotating shaft while permitting relative axial
movement between the first rotating element and the rotating shaft;
a second rotating element; and a second coupling rotationally
securing the second rotating element to the rotating shaft while
permitting relative axial movement between the first rotating
element and the rotating shaft.
44. The apparatus of claim 43 wherein at least one of said first or
second rotating elements is an impeller wheel from a rotary
compressor and said apparatus is an integrated turbogenerator.
45. The apparatus of claim 43 wherein both the first and second
rotating elements are rotating elements of rotary compressors.
46. The apparatus of claim 45 wherein the rotary compressors are
mounted in back-to-back orientation.
47. The apparatus of claim 43 further comprising a motor coupled to
the rotating shaft.
48. The apparatus of claim 43 further comprising a turbine coupled
to the rotating shaft.
49. The apparatus of claim 43 wherein the first coupling is a
multifaceted coupling.
50. The apparatus of claim 43 wherein the first coupling is a
splined coupling.
51. The apparatus of claim 43 further comprising an air bearing
supporting the first rotating element.
52. The apparatus of claim 43 further comprising foil thrust air
bearings supporting the first and second rotating elements.
53. The apparatus of claim 52 wherein said foil thrust air bearings
each comprise an underspring member mounted between a thrust
bearing surface and compliant foil member.
54. The apparatus of claim 43 further comprising a radial air
bearing supporting said rotating shaft.
55. The apparatus of claim 54 wherein said rotating shaft is
connected to a motor shaft through a coupling on the inside
diameter of said radial air bearing that engages a complimentary
coupling on said motor shaft.
56. The apparatus of claim 43 wherein the first and second rotating
elements are components of two back-to-back mounted rotary
compressors.
57. The apparatus of claim 43 wherein the apparatus is a
turbogenerator.
58. The apparatus of claim 57 wherein the first and second rotating
elements are components of rotary compressors in a multi-stage
compression system.
59. A method for mounting components in a compound machine
comprising: rotationally coupling a rotating shaft to a first
rotating element using a coupling that permits relative axial
movement between the first rotating element and the rotating shaft;
and rotationally coupling a second rotating element to the rotating
shaft using a coupling that permits relative axial movement between
the second rotating element and the rotating shaft.
60. The method of claim 59 wherein at least one of the first or
second rotating elements is an impeller wheel from a rotary
compressor.
61. The method of claim 59 wherein both the first and second
rotating elements are components of rotary compressors that are
mounted in opposite directions.
62. The method of claim 59 further comprising coupling the rotating
shaft to a motor.
63. The method of claim 59 further comprising mating a splined
surface of the rotating shaft with a complimentary surface of a
motor shaft.
64. The method of claim 59 further comprising mounting said first
and second rotating elements on air bearings.
65. The method of claim 59 further comprising supporting said
rotating shaft by a radial air bearing.
66. A compound machine comprising: a rotating shaft; a first
rotating component; a second rotating component; a first coupling
rotationally securing the first rotating component to an
intermediate coupling while permitting axial translation of the
first rotating component relative to the intermediate coupling; and
a second coupling rotationally securing the second rotating
component to the intermediate coupling while permitting axial
translation of the second rotating component relative to the
intermediate coupling.
67. The compound machine of claim 66 wherein said first and second
rotating elements are impeller wheels of rotary compressors.
68. The compound machine of claim 66 further comprising: a motor
shaft rotationally coupled to, and axially decoupled from, said
second rotating component by said second coupling.
69. The compound machine of claim 68 wherein said second coupling
is a splined coupling.
70. The compound machine of claim 68 wherein said second coupling
has a multifaceted interface.
71. The compound machine of claim 66 wherein said compound machine
is a turbomachine.
72. The compound machine of claim 68 further comprising radial air
bearings and foil thrust air bearings.
73. The compound machine of claim 68 wherein said compound machine
is an integrated turbogenerator.
74. A turbogenerator having a motor generator driven by a turbine
wheel, the improvement comprising: a multi-stage rotary compressor
comprising a plurality of rotating components and a structure that
rotationally couples but does not axially couple said plurality of
rotating components.
75. The turbogenerator of claim 74 wherein each of said plurality
of rotating components are compressor impeller wheels.
76. The turbogenerator of claim 74 wherein said structure is an
articulated shaft.
77. The turbogenerator of claim 74 wherein each of said plurality
of rotating components are supported by foil thrust air bearings
and said structure is supported by radial air bearings.
78. The turbogenerator of claim 74 wherein at least two stages of
said multi-stage rotary compressor are mounted back-to-back.
79. The turbogenerator of claim 74 wherein said multi-stage rotary
compressor has at least four stages mounted in back-to-back
pairs.
80. A rotationally-driven compound machine comprising: means for
coupling two or more rotating elements of the compound machine to
permit relative axial translation between said rotating elements;
and means for rotationally coupling said rotating elements to a
driving shaft of the compound machine.
81. The rotationally-driven compound machine of claim 80, wherein
said rotating elements are impeller wheels, further comprising
means for supporting said impeller wheels.
82. The rotationally-driven compound machine of claim 80, further
comprising means for supporting said means for coupling two or more
rotating elements.
Description
RELATED APPLICATIONS
[0001] This application claims the priority of U.S. provisional
patent application Serial No. 60/245,835 filed Nov. 3, 2000.
BACKGROUND OF THE INVENTION 1. Field of the Invention
[0002] This invention relates to compound rotary machines, and more
specifically to driving multiple rotary compressors using an
articulated shaft. 2. Description of the Prior Art
[0003] Conventional systems having multiple rotary compressors
generally require significant mechanical tolerances, typically
resulting in inefficient operation.
[0004] What is needed are methods and apparatus for driving
multiple rotary compressors with tight tolerances, permitting
highly efficient system operation.
SUMMARY OF THE INVENTION
[0005] In a first aspect, the present invention provides an
apparatus comprising a plurality of rotary compressors, each having
at least one impeller wheel, and an articulated shaft that
rotationally couples and axially decouples at least one impeller
wheel from each of the plurality of rotary compressors.
[0006] In another aspect, the present invention includes a system
comprising a plurality of rotary compressors, each having at least
one impeller wheel, and a multi-piece shaft that rotationally
couples an impeller wheel from each of the compressors but permits
relative axial movement of the impeller wheels.
[0007] In still another aspect, the present invention includes a
method for rotationally driving a compound machine comprising the
steps of rotationally coupling two or more rotating elements of the
compound machine to permit relative axial translation between said
rotating elements, and rotationally coupling said rotating elements
to a driving shaft of the compound machine.
[0008] In still another aspect, the present invention includes a
turbogenerator comprising a plurality of rotary compressors and
means for rotationally coupling and axially decoupling at least one
impeller wheel from each of the plurality of rotary
compressors.
[0009] In yet another aspect, the present invention includes an
apparatus comprising a rotating shaft, a first rotating element, a
first coupling rotationally securing the first rotating element to
the rotating shaft while permitting relative axial movement between
the first rotating element and the rotating shaft, a second
rotating element, and a second coupling rotationally securing the
second rotating element to the rotating shaft while permitting
relative axial movement between the first rotating element and the
rotating shaft.
[0010] In still another aspect, the present invention includes a
method for mounting components in a compound machine comprising
rotationally coupling a rotating shaft to a first rotating element
using a coupling that permits relative axial movement between the
first rotating element and the rotating shaft, and rotationally
coupling a second rotating element to the rotating shaft using a
coupling that permits relative axial movement between the second
rotating element and the rotating shaft.
[0011] In yet another aspect, the present invention includes a
compound machine comprising a rotating shaft, a first rotating
component, a second rotating component, a first coupling
rotationally securing the first rotating component to an
intermediate coupling while permitting axial translation of the
first rotating component relative to the intermediate coupling, and
a second coupling rotationally securing the second rotating
component to the intermediate coupling while permitting axial
translation of the second rotating component relative to the
intermediate coupling.
[0012] In still another aspect, the present invention includes a
turbogenerator having a motor generator driven by a turbine wheel,
wherein the improvement comprises a multi-stage rotary compressor
comprising a plurality of rotating components and a structure that
rotationally couples but does not axially couple said plurality of
rotating components.
[0013] In still another aspect, the present invention includes a
rotationally-driven compound machine comprising means for coupling
two or more rotating elements of the compound machine to permit
relative axial translation between said rotating elements, and
means for rotationally coupling said rotating elements to a driving
shaft of the compound machine.
[0014] These and other features and advantages of this invention
will become further apparent from the detailed description and
accompanying figures that follow. In the figures and description,
numerals indicate the various features of the invention, like
numerals referring to like features throughout both the drawings
and the description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A is perspective view, partially in section, of an
integrated turbogenerator system.
[0016] FIG. 1B is a magnified perspective view, partially in
section, of the motor/generator portion of the integrated
turbogenerator of FIG. 1A.
[0017] FIG. 1C is an end view, from the motor/generator end, of the
integrated turbogenerator of FIG. 1A.
[0018] FIG. 1D is a magnified perspective view, partially in
section, of the combustor-turbine exhaust portion of the integrated
turbogenerator of FIG. 1A.
[0019] FIG. 1E is a magnified perspective view, partially in
section, of the compressor-turbine portion of the integrated
turbogenerator of FIG. 1A.
[0020] FIG. 2 is a block diagram schematic of a turbogenerator
system including a power controller having decoupled rotor speed,
operating temperature, and DC bus voltage control loops.
[0021] FIG. 3 is a side view in cross section of an embodiment
having four compressors mounted on an air bearing articulated
shaft.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0022] One preferred embodiment of the present invention is in
connection with a turbogenerator, such as an integrated small-scale
turbogeneration unit.
Mechanical Structural Embodiment of a Turbogenerator
[0023] With reference to FIG. 1A, an integrated turbogenerator 1
generally includes motor/generator section 10 and
compressor-combustor section 30. Compressor-combustor section 30
includes exterior can 32, compressor 40, combustor 50 and turbine
70. A recuperator 90 may be optionally included.
[0024] Referring now to FIG. 1B and FIG. 1C, in a currently
preferred embodiment, motor/generator section 10 may be a permanent
magnet motor generator having a permanent magnet rotor or sleeve
12. Any other suitable type of motor generator may also be used.
Permanent magnet rotor or sleeve 12 may contain a permanent magnet
12M. Permanent magnet rotor or sleeve 12 and the permanent magnet
disposed therein are rotatably supported within permanent magnet
motor/generator stator 14. Preferably, one or more compliant foil,
fluid film, radial, or journal bearings 15A and 15B rotatably
support permanent magnet rotor or sleeve 12 and the permanent
magnet disposed therein. All bearings, thrust, radial or journal
bearings, in turbogenerator 1 may be fluid film bearings or
compliant foil bearings. Motor/generator housing 16 encloses stator
heat exchanger 17 having a plurality of radially extending stator
cooling fins 18. Stator cooling fins 18 connect to or form part of
stator 14 and extend into annular space 10A between motor/generator
housing 16 and stator 14. Wire windings 14W exist on permanent
magnet motor/generator stator 14.
[0025] Referring now to FIG. 1D, combustor 50 may include
cylindrical inner wall 52 and cylindrical outer wall 54.
Cylindrical outer wall 54 may also include air inlets 55.
Cylindrical walls 52 and 54 define an annular interior space 50S in
combustor 50 defining an axis 51. Combustor 50 includes a generally
annular wall 56 further defining one axial end of the annular
interior space of combustor 50. Associated with combustor 50 may be
one or more fuel injector inlets 58 to accommodate fuel injectors
which receive fuel from fuel control element 50P as shown in FIG.
2, and inject fuel or a fuel air mixture to interior of 50S
combustor 50. Inner cylindrical surface 53 is interior to
cylindrical inner wall 52 and forms exhaust duct 59 for turbine
70.
[0026] Turbine 70 may include turbine wheel 72. An end of combustor
50 opposite annular wall 56 further defines an aperture 71 in
turbine 70 exposed to turbine wheel 72. Bearing rotor 74 may
include a radially extending thrust bearing portion, bearing rotor
thrust disk 78, constrained by bilateral thrust bearings 78A and
78B. Bearing rotor 74 may be rotatably supported by one or more
journal bearings 75 within center bearing housing 79. Bearing rotor
thrust disk 78 at the compressor end of bearing rotor 76 is
rotatably supported preferably by a bilateral thrust bearing 78A
and 78B. Journal or radial bearing 75 and thrust bearings 78A and
78B may be fluid film or foil bearings.
[0027] Turbine wheel 72, Bearing rotor 74 and compressor impeller
42 may be mechanically constrained by tie bolt 74B, or other
suitable technique, to rotate when turbine wheel 72 rotates.
Mechanical link 76 mechanically constrains compressor impeller 42
to permanent magnet rotor or sleeve 12 and the permanent magnet
disposed therein causing permanent magnet rotor or sleeve 12 and
the permanent magnet disposed therein to rotate when compressor
impeller 42 rotates.
[0028] Referring now to FIG. 1E, compressor 40 may include
compressor impeller 42 and compressor impeller housing 44.
Recuperator 90 may have an annular shape defined by cylindrical
recuperator inner wall 92 and cylindrical recuperator outer wall
94. Recuperator 90 contains internal passages for gas flow, one set
of passages, passages 33 connecting from compressor 40 to combustor
50, and one set of passages, passages 97, connecting from turbine
exhaust 80 to turbogenerator exhaust output 2.
[0029] Referring again to FIG. 1B and FIG. 1C, in operation, air
flows into primary inlet 20 and divides into compressor air 22 and
motor/generator cooling air 24. Motor/generator cooling air 24
flows into annular space 10A between motor/generator housing 16 and
permanent magnet motor/generator stator 14 along flow path 24A.
Heat is exchanged from stator cooling fins 18 to generator cooling
air 24 in flow path 24A, thereby cooling stator cooling fins 18 and
stator 14 and forming heated air 24B. Warm stator cooling air 24B
exits stator heat exchanger 17 into stator cavity 25 where it
further divides into stator return cooling air 27 and rotor cooling
air 28. Rotor cooling air 28 passes around stator end 13A and
travels along rotor or sleeve 12. Stator return cooling air 27
enters one or more cooling ducts 14D and is conducted through
stator 14 to provide further cooling. Stator return cooling air 27
and rotor cooling air 28 rejoin in stator cavity 29 and are drawn
out of the motor/generator 10 by exhaust fan 11 which is connected
to rotor or sleeve 12 and rotates with rotor or sleeve 12. Exhaust
air 27B is conducted away from primary air inlet 20 by duct
10D.
[0030] Referring again to FIG. 1E, compressor 40 receives
compressor air 22. Compressor impeller 42 compresses compressor air
22 and forces compressed gas 22C to flow into a set of passages 33
in recuperator 90 connecting compressor 40 to combustor 50. In
passages 33 in recuperator 90, heat is exchanged from walls 98 of
recuperator 90 to compressed gas 22C. As shown in FIG. 1E, heated
compressed gas 22H flows out of recuperator 90 to space 35 between
cylindrical inner surface 82 of turbine exhaust 80 and cylindrical
outer wall 54 of combustor 50. Heated compressed gas 22H may flow
into combustor 54 through sidewall ports 55 or main inlet 57. Fuel
(not shown) may be reacted in combustor 50, converting chemically
stored energy to heat. Hot compressed gas 51 in combustor 50 flows
through turbine 70 forcing turbine wheel 72 to rotate. Movement of
surfaces of turbine wheel 72 away from gas molecules partially
cools and decompresses gas 51D moving through turbine 70. Turbine
70 is designed so that exhaust gas 107 flowing from combustor 50
through turbine 70 enters cylindrical passage 59. Partially cooled
and decompressed gas in cylindrical passage 59 flows axially in a
direction away from permanent magnet motor/generator section 10,
and then radially outward, and then axially in a direction toward
permanent magnet motor/generator section 10 to passages 98 of
recuperator 90, as indicated by gas flow arrows 108 and 109
respectively
[0031] In an alternate embodiment, low pressure catalytic reactor
80A may be included between fuel injector inlets 58 and recuperator
90. Low pressure catalytic reactor 80A may include internal
surfaces (not shown) having catalytic material (e.g., Pd or Pt, not
shown) disposed on them. Low pressure catalytic reactor 80A may
have a generally annular shape defined by cylindrical inner surface
82 and cylindrical low pressure outer surface 84. Unreacted and
incompletely reacted hydrocarbons in gas in low pressure catalytic
reactor 80A react to convert chemically stored energy into
additional heat, and to lower concentrations of partial reaction
products, such as harmful emissions including nitrous oxides
(NOx).
[0032] Gas 110 flows through passages 97 in recuperator 90
connecting from turbine exhaust 80 or catalytic reactor 80A to
turbogenerator exhaust output 2, as indicated by gas flow arrow
112, and then exhausts from turbogenerator 1, as indicated by gas
flow arrow 113. Gas flowing through passages 97 in recuperator 90
connecting from turbine exhaust 80 to outside of turbogenerator 1
exchanges heat to walls 98 of recuperator 90. Walls 98 of
recuperator 90 heated by gas flowing from turbine exhaust 80
exchange heat to gas 22C flowing in recuperator 90 from compressor
40 to combustor 50.
[0033] Turbogenerator 1 may also include various electrical sensor
and control lines for providing feedback to power controller 201
and for receiving and implementing control signals as shown in FIG.
2.
[0034] Alternative Mechanical Structural Embodiments of the
Integrated Turbogenerator
[0035] The integrated turbogenerator disclosed above is exemplary.
Several alternative structural embodiments are known
[0036] In one alternative embodiment, air 22 may be replaced by a
gaseous fuel mixture. In this embodiment, fuel injectors may not be
necessary. This embodiment may include an air and fuel mixer
upstream of compressor 40.
[0037] In another alternative embodiment, fuel may be conducted
directly to compressor 40, for example by a fuel conduit connecting
to compressor impeller housing 44. Fuel and air may be mixed by
action of the compressor impeller 42. In this embodiment, fuel
injectors may not be necessary.
[0038] In another alternative embodiment, combustor 50 may be a
catalytic combustor.
[0039] In another alternative embodiment, geometric relationships
and structures of components may differ from those shown in FIG.
1A. Permanent magnet motor/generator section 10 and
compressor/combustor section 30 may have low pressure catalytic
reactor 80A outside of annular recuperator 90, and may have
recuperator 90 outside of low pressure catalytic reactor 80A. Low
pressure catalytic reactor 80A may be disposed at least partially
in cylindrical passage 59, or in a passage of any shape confined by
an inner wall of combustor 50. Combustor 50 and low pressure
catalytic reactor 80A may be substantially or completely enclosed
with an interior space formed by a generally annularly shaped
recuperator 90, or a recuperator 90 shaped to substantially enclose
both combustor 50 and low pressure catalytic reactor 80A on all but
one face.
[0040] Alternative uses other than in Integrated
Turbogenerators
[0041] An integrated turbogenerator is a turbogenerator in which
the turbine, compressor, and generator are all constrained to
rotate based upon rotation of the shaft to which the turbine is
connected. The concepts disclosed herein are preferably but not
necessarily used in connection with a turbogenerator, and
preferably but not necessarily used in connection with an
integrated turbogenerator.
[0042] Turbogenerator System Including Controls
[0043] Referring now to FIG. 2, a preferred embodiment is shown in
which a turbogenerator system 200 includes power controller 201
which has three substantially decoupled control loops for
controlling (1) rotary speed, (21) temperature, and (3) DC bus
voltage. A more detailed description of an appropriate power
controller is disclosed in U.S. patent application Ser. No.
09/207,817, filed Dec. 8, 1998 in the names of Gilbreth, Wacknov
and Wall, and assigned to the assignee of the present application
which is incorporated herein in its entirety by this reference.
[0044] Referring still to FIG. 2, turbogenerator system 200
includes integrated turbogenerator 1 and power controller 201.
Power controller 201 includes three decoupled or independent
control loops.
[0045] A first control loop, temperature control loop 228,
regulates a temperature related to the desired operating
temperature of primary combustor 50 to a set point, by varying fuel
flow from fuel control element 50P to primary combustor 50.
Temperature controller 228C receives a temperature set point, T*,
from temperature set point source 232, and receives a measured
temperature from temperature sensor 226S connected to measured
temperature line 226. Temperature controller 228C generates and
transmits over fuel control signal line 230 to fuel pump 50P a fuel
control signal for controlling the amount of fuel supplied by fuel
pump 50P to primary combustor 50 to an amount intended to result in
a desired operating temperature in primary combustor 50.
Temperature sensor 226S may directly measure the temperature in
primary combustor 50 or may measure a temperature of an element or
area from which the temperature in the primary combustor 50 may be
inferred.
[0046] A second control loop, speed control loop 216, controls
speed of the shaft common to the turbine 70, compressor 40, and
motor/generator 10, hereafter referred to as the common shaft, by
varying torque applied by the motor generator to the common shaft.
Torque applied by the motor generator to the common shaft depends
upon power or current drawn from or pumped into windings of
motor/generator 10. Bi-directional generator power converter 202 is
controlled by rotor speed controller 216C to transmit power or
current in or out of motor/generator 10, as indicated by
bi-directional arrow 242. A sensor in turbogenerator 1 senses the
rotary speed on the common shaft and transmits that rotary speed
signal over measured speed line 220. Rotor speed controller 216
receives the rotary speed signal from measured speed line 220 and a
rotary speed set point signal from a rotary speed set point source
218. Rotary speed controller 216C generates and transmits to
generator power converter 202 a power conversion control signal on
line 222 controlling generator power converter 202's transfer of
power or current between AC lines 203 (i.e., from motor/generator
10) and DC bus 204. Rotary speed set point source 218 may convert
to the rotary speed set point a power set point P* received from
power set point source 224.
[0047] A third control loop, voltage control loop 234, controls bus
voltage on DC bus 204 to a set point by transferring power or
voltage between DC bus 204 and any of (1) Load/Grid 208 and/or (2)
energy storage device 210, and/or (3) by transferring power or
voltage from DC bus 204 to dynamic brake resistor 214. A sensor
measures voltage DC bus 204 and transmits a measured voltage signal
over measured voltage line 236. Bus voltage controller 234C
receives the measured voltage signal from voltage line 236 and a
voltage set point signal V* from voltage set point source 238. Bus
voltage controller 234C generates and transmits signals to
bi-directional load power converter 206 and bi-directional battery
power converter 212 controlling their transmission of power or
voltage between DC bus 204, load/grid 208, and energy storage
device 210, respectively. In addition, bus voltage controller 234
transmits a control signal to control connection of dynamic brake
resistor 214 to DC bus 204.
[0048] Power controller 201 regulates temperature to a set point by
varying fuel flow, adds or removes power or current to
motor/generator 10 under control of generator power converter 202
to control rotor speed to a set point as indicated by
bi-directional arrow 242, and controls bus voltage to a set point
by (1) applying or removing power from DC bus 204 under the control
of load power converter 206 as indicated by bi-directional arrow
244, (2) applying or removing power from energy storage device 210
under the control of battery power converter 212, and (3) by
removing power from DC bus 204 by modulating the connection of
dynamic brake resistor 214 to DC bus 204.
[0049] Mounting Multiple Compressors using an Articulated Shaft
[0050] Rotary compressors typically place an axial load, in a
direction opposite to the gas flow out of the compressor, on the
housing to which they are mounted. Mechanical tolerances are
therefore required to account for movement of such compressors,
during operation, relative to the surrounding components of the
system in which they are mounted. Where multiple compressors are
mechanically connected, independent tolerances are required for
each compressor, resulting in a net tolerance approaching the sum
of each of the individual tolerances required for each compressor.
Multi-compressor systems accordingly can have considerable
tolerance requirements, resulting in system operation that is less
than optimally efficient. The need for additive tolerances in
multi-compressor systems can be alleviated in some instances
through the use of back-to-back compressor mounting.
[0051] Referring now to FIG. 3, a side view of a cross section of
an embodiment having four compressors 350, 352, 354 and 356 mounted
on an air bearing articulated shaft is illustrated. Each of these
compressors are preferably one of four stages of a multistage
compression system designed to compress gas. Impeller wheels 300,
302, 304, 306 of each of the four compressors rotate within
cylindrical recesses 334, 340, 342 and 344, respectively. The
lateral movement of impeller wheel 300, for example, is bounded on
the right-hand side by housing face 338 and is bounded on the right
hand side by housing face 336.
[0052] Compressor 350 expels its compressed gas stream in a
leftward direction, imparting a rightward force on impeller wheel
300 relative to the surrounding housing. To facilitate the rotation
of impeller wheel 300, and to prevent it from grinding against
housing face 336, the system is equipped with thrust air bearings
326, such as a foil thrust bearings constructed with a thin,
compliant aerofoil member. The compliant foil member of the foil
thrust bearing may include an underspring member mounted on the
thrust bearing surface and disposed between the thrust bearing
surface and compliant foil member. The underspring member may have
variable spring stiffness in both the circumferential and radial
directions. The aerofoil may be clamped to the housing face 336, or
could be clamped to and rotate with the right-hand side of impeller
wheel 300. Each of the other impeller wheels 302, 304 and 306 may
similarly be equipped with thrust air bearings, preferably on the
side of the impeller wheel on which the compressor is pressed
against the housing by the forces generated by its operation. As
illustrated in FIG. 3, impeller wheels 302, 304 and 306 are
supported in part by thrust air bearings 328, 330 and 332,
respectively. Further description of thrust air bearings that may
be used with this implementation is set forth in U.S. patent
application Ser. No. 09/714,349, filed Nov. 15, 2000 and assigned
to the asignee of the present application, and U.S. Pat. Nos.
5,529,398, 5,791,868, 5,827,040, 5,918,985, and 6,158,892, which
are hereby incorporated by reference.
[0053] To partially offset the forces imparted by impeller wheels
300 and 302 on the surrounding housing, including the forces
imparted by impeller wheel 300 on housing faces 336 and 338,
compressors 350 and 352 may be mounted back-to-back. In this
orientation, the rightward force of impeller wheel 300 offsets to
some extent the leftward force of impeller wheel 302. Similarly,
compressors 354 and 356 may be mounted in a back-to-back
orientation so that they work against each other. Although such
back-to-back mounting reduces the net forces of the compressors on
their surrounding housing, it usually does not alleviate these
forces altogether, particularly where each of the compressors is a
single stage of a multi-stage compression arrangement because the
axial load imparted by a rotary compressor is dependent upon the
compression level of the gas it processes.
[0054] Optimally each compressor 350, 352, 354 and 356 in
multi-stage compression arrangement 301 is independently floated as
illustrated in FIG. 3. Independent axial suspension of each
compressor may be accomplished using an articulated shaft such as
shaft 303 to drive the compressors. An articulated shaft is a shaft
having multiple pieces and a common axis, the pieces of which can
move relative to one another. The multiple pieces comprising
multi-piece shaft 303 include rotating connector 314, articulated
connector 316 and rotating connector 318. More specifically,
impeller wheel 300 is attached to rotating connector 318 which is,
in turn, connected in splined engagement with articulated connector
316. Impeller wheel 302 is attached to rotating connector 314 which
is, in turn, connected to motor shaft 310 on one end and to
articulated connector 316 on the other end. Rotating connectors 314
and 318 rotationally couple impeller wheels 300 and 302,
respectively, to motor shaft 310, while permitting axial movement
of impeller wheels 300 and 302 relative to each other, to motor 308
and to motor shaft 310. The components coupled by articulated shaft
303, comprised on the right-hand side 346 of motor 308 by
articulated connector 316 and rotating connectors 314 and 318, are
coupled rotationally but not axially.
[0055] Analogous components on the left-hand side 348 of motor 308
may be similarly connected. In one preferred embodiment, impeller
wheel 306 is attached to rotating connector 324 which is, in turn,
connected in splined or other suitable engagement with articulated
connector 322. For example, the surface of rotating connector 324
that interfaces with articulated connector 322 may contain a
plurality of teeth, each of which intermeshes with complimentary
slots on a hub of the articulated connector 322 continuously during
operation. The teeth are shaped and oriented so that the toothed
components can move axially, but not rotationally, with respect to
each other. A similar interconnection may be used between
articulated connector 322 and rotating connector 320, and between
rotating connector 320 and motor shaft 312, as well as between the
analogous components on the right-hand side of motor 308. Impeller
wheel 304 is attached to rotating connector 320 which is, in turn,
connected to motor shaft 312 on one end and to articulated
connector 322 on the other end. Rotating connectors 320 and 324
thereby rotationally couple impeller wheels 304 and 306,
respectively, to motor shaft 312, while permitting axial movement
of impeller wheels 304 and 306 relative to each other, to motor 308
and to motor shaft 312.
[0056] The use of a splined interconnection in some implementations
may necessitate the use of lubricants or coatings to facilitate
axial translation. The above-described rotating and articulated
connectors may be interlinked through couplings other than a
splined interface. For example, these components may be interlinked
by gears or by mating pairs of complementary geometric shapes other
than teeth, such as triangles or squares. The engagement between
rotating connector 314 and motor shaft 310, between rotating
connector 314 and articulated connector 316, and between
articulated connector 316 and rotating connector 318 may, by way of
further example, be multifaceted or engaged in any suitable fashion
providing secure rotational attachment and permitting independent
axial translation. Alternative suitable interconnection techniques,
including a double diaphram coupling, are described in further
detail in U.S. Pat. Nos. 5,964,663, 6,037,687 and 6,094,799, which
are assigned to the assignee of the present invention and are
incorporated by reference herein.
[0057] The above-described articulated shafts are preferably
supported by radial air bearings 358 and 360. In some embodiments
the radial air bearings 358 and 360 support some, but not all, of
the components of the articulated shafts. The motor shafts 310
and/or 312 may also be supported by radial air bearings. In some
embodiments, the motor shafts are supported by a splined coupling
on each end that engages the inside diameter of the air bearings.
These bearings are generally comprised of a bushing, a rotating
element such as a rotor or shaft adapted to rotate within the
bushing, non-rotating compliant fluid foil members mounted within
the bushing and enclosing the rotating element, and non-rotating
compliant spring foil members mounted within the bushing underneath
the non-rotating compliant fluid foil members. The space between
the rotating element and the bushing is filled with fluid, such as
air or other suitable fluids, which envelops the foils. The motion
of the rotating element applies viscous drag forces to the fluid in
converging wedge channels. This results in increases in fluid
pressure, especially near the trailing end of the wedge channels.
If the rotating element moves toward the non-rotating element, the
convergence angle of the wedge channel increases, causing the fluid
pressure rise along the channel to increase. Conversely, if the
rotating element moves away, the pressure rise along the wedge
channel decreases. Thus, the fluid in the wedge channels exerts
restoring forces on the rotating element that vary with and
stabilize running clearances and prevent contact between the
rotating and non-rotating elements of the bearing. Exemplary air
bearing apparatus, and related matter, is further described in U.S.
Pat. Nos. 6,190,048 and 6,158,892, which are incorporated herein by
this reference.
[0058] The above-described arrangement of components permits
multiple compressor modules to self-align and float, thereby
minimizing their interference with the associated stationary parts
of the system into which they are incorporated. The foregoing
techniques may be suitably applied to any rotary compound
machine.
[0059] Having now described the invention in accordance with the
requirements of the patent statutes, those skilled in this art will
understand how to make changes and modifications in the present
invention to meet their specific requirements or conditions. Such
changes and modifications may be made without departing from the
scope and spirit of the invention as set forth in the following
claims.
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