U.S. patent application number 12/082298 was filed with the patent office on 2009-10-15 for diffuser.
Invention is credited to Giusto Fonda-Bonardi.
Application Number | 20090257868 12/082298 |
Document ID | / |
Family ID | 41164141 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090257868 |
Kind Code |
A1 |
Fonda-Bonardi; Giusto |
October 15, 2009 |
Diffuser
Abstract
An improved diffuser apparatus for use in connection with gas
turbines that will markedly increase the fuel efficiency of the
turbine. The improved diffuser apparatus improves the performance
of the diffuser apparatus by insuring that the gas flow supplied by
the turbine is free from unnecessary energy losses due to
improperly located mechanical structures. More particularly, the
prior art turbine is modified in a manner to incorporate into the
diffuser itself certain of the mechanical structures that
previously formed a part of the structure of the turbine.
Inventors: |
Fonda-Bonardi; Giusto;
(Santa Monica, CA) |
Correspondence
Address: |
JAMES E. BRUNTON, ESQ.
P. O. BOX 29000
GLENDALE
CA
91209
US
|
Family ID: |
41164141 |
Appl. No.: |
12/082298 |
Filed: |
April 9, 2008 |
Current U.S.
Class: |
415/211.2 ;
415/57.1; 415/58.4 |
Current CPC
Class: |
F01D 25/305
20130101 |
Class at
Publication: |
415/211.2 ;
415/58.4; 415/57.1 |
International
Class: |
F01D 9/02 20060101
F01D009/02; F01D 1/12 20060101 F01D001/12; F01D 25/24 20060101
F01D025/24 |
Claims
1. A diffuser apparatus for use in connection with a gas turbine of
the character having a rotatable power shaft and a plurality of
rotating turbine blades, a high velocity gas stream exiting the
turbine blades, said apparatus comprising: (a) a central hub for
supporting said rotatable power shaft of said turbine; (b) a shroud
circumscribing said hub, said shroud having inner and outer walls
defining an enclosure having a first open end disposed proximate
the turbine blades to receive the high velocity gas stream, and a
second discharge end for exhausting gases of said high velocity gas
stream, said inner wall of said shroud having first injector slots
provided therein and said outer wall of said shroud having second
injector slots provided therein; (c) capture means disposed
proximate said second discharge end of said enclosure for capturing
a portion of the gases of said high velocity gas stream; (d) first
combination conduit and structural support member for providing
rigidity to the diffuser and for directing a portion of the high
velocity gas stream captured by said capture means toward said
first injector slots provided in said inner wall of said shroud;
and (e) a second combination conduit and structural support member
for providing rigidity to the diffuser and for directing a portion
of the high velocity gas stream captured by said capture means
toward said second injector slots provided in said outer wall of
said shroud.
2. The diffuser apparatus as defined in claim 1 in which said
capture means comprises a generally toroidal-shaped capture
scoop.
3. The diffuser apparatus as defined in claim 2 further including
collector means circumscribing said discharge end of said shroud
for collecting gases flowing therefrom, said generally
toroidal-shaped scoop being disposed interiorly of said collector
means.
4. The diffuser apparatus as defined in claim 3 in which said
collector means further includes: (a) a first combination plenum
and structural support member circumscribing at least a portion of
said inner wall of said shroud for providing rigidity to the
diffuser, said first combination plenum and structural support
member having a gas inlet and a gas outlet communicating with said
first injector slots; and (b) a second combination plenum and
structural support member circumscribing at least a portion of said
outer wall of said shroud for providing rigidity to the diffuser,
said second combination plenum and structural support member having
a gas inlet and a gas outlet communicating with said second
injector slots.
5. The diffuser apparatus as defined in claim 4 in which said
collector means further includes an inner structural ring connected
to said central hub and to said first combination plenum and
structural support member.
6. The diffuser apparatus as defined in claim 4 which said
collector means further includes an outer structural ring connected
to said central hub and to said second combination plenum and
structural support member.
7. The diffuser apparatus as defined in claim 6 further including:
(a) a first reinforcement plate or built-up structure connected to
said first combination conduit and structural support member; and
(b) a ground plate or built-up structure connected to said first
reinforcement plate or build-up structure.
8. The diffuser apparatus as defined in claim 7, further including
a second reinforcement plate connected to said second combination
conduit and structural support member.
9. A diffuser apparatus for use in connection with a gas turbine of
the character having a rotatable power shaft and a plurality of
rotating turbine blades, a high velocity gas stream exiting the
turbine blades, said apparatus comprising: (a) a central hub for
supporting said rotatable power shaft of said turbine; (b) a shroud
circumscribing said hub, said shroud having inner and outer walls
defining an enclosure having a first open end disposed proximate
the turbine blades to receive the high velocity gas stream, and a
second discharge end for exhausting gases of said high velocity gas
stream, said inner wall of said shroud having first injector slots
provided therein and said outer wall of said shroud having second
injector slots provided therein; (c) capture means disposed
proximate said second discharge end of said enclosure for capturing
a portion of the gases of said high velocity gas stream, said
capture means comprising a generally toroidal-shaped capture scoop;
(d) collector means circumscribing said discharge end of said
shroud for collecting gases flowing therefrom, said generally
toroidal-shaped scoop being disposed interiorly of said collector
means; (e) first combination conduit and structural support member
for providing rigidity to the diffuser, for maintaining
concentricity between said hub and said shroud during operation and
for directing a portion of the high velocity gas stream captured by
said capture means toward said first injector slots provided in
said inner wall of said shroud; and (f) a second combination
conduit and structural support member for providing rigidity to the
diffuser, for maintaining concentricity between said hub and said
shroud during operation and for directing a portion of the high
velocity gas stream captured by said capture means toward said
second injector slots provided in said outer wall of said
shroud.
10. The diffuser apparatus as defined in claim 9 in which said
collector means further includes: (a) a first combination plenum
and structural support member circumscribing at least a portion of
said inner wall of said shroud for providing rigidity to the
diffuser and for maintaining concentricity between said hub and
said shroud during operation, said first combination plenum and
structural support member having a gas inlet and a gas outlet
communicating with said first injector slots; and (b) a second
combination plenum and structural support member circumscribing at
least a portion of said outer wall of said shroud for providing
rigidity to the diffuser and for maintaining concentricity between
said hub and said shroud during operation, said second combination
plenum and structural support member having a gas inlet and a gas
outlet communicating with said second injector slots.
11. A diffuser apparatus as defined in claim 9 in which said
collector means further includes an inner structural ring connected
to said central hub and to said first combination plenum and
structural support member.
12. A diffuser apparatus as defined in claim 9 in which said
collector means further includes an outer structural ring connected
to said central hub and to said second combination plenum and
structural support member.
13. A diffuser apparatus for use in connection with a gas turbine
of the character having a rotatable power shaft and a plurality of
rotating turbine blades, a high velocity gas stream exiting the
turbine blades, said apparatus comprising: (a) a central hub for
rotatably supporting the power shaft of the turbine; (b) a shroud
circumscribing said hub, said shroud having inner and outer walls
defining an enclosure having a first open end disposed proximate
the turbine blades to receive the high velocity gas stream, and a
second discharge end for exhausting gases of said high velocity gas
stream, said inner wall of said shroud having first injector slots
provided therein and said outer wall of said shroud having second
injector slots provided therein; (c) capture means disposed
proximate said second discharge end of said enclosure for capturing
a portion of the gases of said high velocity gas stream, said
capture means comprising a generally toroidal-shaped capture scoop;
(d) collector means circumscribing said discharge end of said
shroud for collecting gases flowing therefrom, said generally
toroidal-shaped scoop being disposed interiorly of said collector
means, said collector means further comprising: (i) a first
combination plenum and structural support member circumscribing at
least a portion of said inner wall of said shroud for providing
rigidity to the diffuser and for maintaining concentricity between
said hub and said shroud during operation, said first combination
plenum and structural support member having a gas inlet and a gas
outlet communicating with said first injector slots; and (ii) a
second combination plenum and structural support member
circumscribing at least a portion of said outer wall of said shroud
for providing rigidity to the diffuser and for maintaining
concentricity between said hub and said shroud during operation,
said second combination plenum and structural support member having
a gas inlet and a gas outlet communicating with said second
injector slots; and (e) first combination conduit and structural
support member for providing rigidity to the diffuser, for
maintaining concentricity between said hub and said shroud during
operation and for directing a portion of the high velocity gas
stream captured by said capture means toward said first injector
slots provided in said inner wall of said shroud; and (f) a second
combination conduit and structural support member for providing
rigidity to the diffuser, for maintaining concentricity between
said hub and said shroud during operation and for directing a
portion of the high velocity gas stream captured by said capture
means toward said second injector slots provided in said outer wall
of said shroud.
14. A diffuser apparatus as defined in claim 13 in which said
collector means further includes an inner structural ring connected
to said central hub and to said first combination plenum and
structural support member.
15. A diffuser apparatus as defined in claim 14 which said
collector means further includes an outer structural ring connected
to said central hub and to said second combination plenum and
structural support member.
16. The diffuser apparatus as defined in claim 15 further including
a reinforcing structure connected to said first combination
conduit.
17. The diffuser apparatus as defined in claim 16 in which said
reinforcing structure comprises: (a) a first generally vertically
extending reinforcement plate or built-up structure connected to
said first combination conduit and structural support member; and
(b) a ground-engaging plate or build-up structure connected to said
first reinforcement structure and operably associated with said
first generally vertically extending reinforcement structure.
18. The diffuser apparatus as defined in claim 17 in which said
reinforcing structure further includes a second reinforcement plate
or built-up structure connected to said second combination conduit
and structural support member.
19. The diffuser apparatus as defined in claim 18 in which the
diffuser has a vertical plane of symmetry and in which said first
reinforcement plate or built-up structure is located in the
vertical plane of symmetry of the diffuser.
20. The diffuser apparatus as defined in claim 19 in which said
first and second reinforcement plates or built-up structures are
located symmetrically around said first and second conduits.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to devices for the
transformation of part of the kinetic energy of a moving fluid into
pressure of the fluid. More particularly the invention concerns a
diffuser for use in connection with gas turbines, where an
improvement of performance is obtained at the interface between the
turbine and the diffuser.
[0003] 2. Discussion of the Prior Art
[0004] Novel and highly successful short subsonic diffusers are
described in U.S. Pat. Nos. 3,599,431, 4,029,430 and 5,603,605, all
issued to the present inventor. Because of the pertinence of these
three patents, and because the present invention comprises an
improvement over the inventions disclosed in these patents, U.S.
Pat. Nos. 3,599,431, 4,029,430, and 5,603;605 are incorporated by
reference as though fully set forth herein.
[0005] The diffusers described in detail in the incorporated by
reference patents recover a major fraction of the kinetic energy in
the stream of gas issuing from the last stage of the turbine and
efficiently transform it into an increment of static pressure and,
therefore, results in an improvement of the thermodynamic
efficiency of the turbine. However, a part of the kinetic energy of
the gas at the inlet of the diffuser is not available for recovery
because the original design of the turbine did not contemplate the
possibility of the level of energy recovery enabled by the advanced
diffuser of the present invention; hence, attention to the
interface between the turbine and the diffuser permits an
additional pressure recovery increment if the diffuser corrects the
defects in the flow of the gas from the last stage of the
turbine.
[0006] Accordingly, the improved diffuser of the present invention
is instantiated by transferring to the structure of the diffuser
certain mechanical elements that are traditionally part of the
turbine structure downstream of the last stage of the turbine. The
removal of these mechanical elements from the turbine improves the
gas flow to the diffuser and hence improves the energy recovery by
the diffuser. As will be discussed in greater detail in the
paragraphs that follow, the original function of these mechanical
elements can be uniquely incorporated into the structure of the
diffuser in such a way as to not affect the mechanical performance
of the turbine, while at the same time relying upon the diffuser
itself to provide the necessary structural support.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide a
diffuser apparatus for use in connection with gas turbines that
will markedly increase the fuel efficiency of the turbine.
[0008] More particularly it is an object of the present invention
to improve the performance of the diffuser apparatus by insuring
that the gas flow supplied by the turbine is free from unnecessary
energy losses due to improperly located mechanical structures.
[0009] Another object of the invention is to modify the prior art
turbine in a manner to incorporate into the diffuser itself certain
of the mechanical structures that previously formed a part of the
structure of the turbine.
[0010] Another object of the invention is to modify the prior art
turbine in the manner described in the preceding of paragraph
without adversely affecting the aerodynamic function of the
diffuser.
[0011] Another object of the invention is to identify the stress
path in the structure of the diffuser to insure adequate rigidity
against deformations previously resisted by the structural elements
of the turbine that were removed from the turbine and incorporated
into the diffuser itself.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a side-elevational, cross-sectional view of one
form of prior art diffuser structure that can be modified in
accordance with the methods of the present invention.
[0013] FIG. 2 is a side elevational, cross-sectional view similar
to FIG. 1, but showing the structural elements that formed a part
of the prior art diffuser structure, but were, for sake of clarity,
eliminated from FIG. 1 of the '605 patent.
[0014] FIG. 3 is a side-elevational, cross-sectional view of one
form of the improved diffuser of the present invention.
[0015] FIG. 4, is a side-elevational, cross-sectional view of an
alternate form of the improved diffuser of the invention.
DESCRIPTION OF THE INVENTION
[0016] Referring particularly to FIG. 1, one form of prior art
apparatus that can be modified in accordance with the methods of
the present invention is there shown. More particularly, FIG. 1
illustrates the apparatus shown and described in incorporated by
reference U.S. Pat. No. 5,603,605 ('605) that comprises a diffuser
coupled with a gas turbine of conventional construction. It is to
be noted that the diffuser structure of this prior art apparatus is
symmetrical about the axis 34 of the turbine. The turbine portion
of the apparatus includes a power shaft 36 that comprises rotating
hub 38 to which a plurality of outwardly extending turbine blades
39 are affixed. Circumscribing shaft 36 is a diffuser shroud 40
having inner and outer walls 42 and 44 respectively. As indicated
in FIG. 1, the inner open mouth 46 of the shroud 40 is disposed
proximate blades 39 of the turbine and functions to receive the
high velocity gas stream generated by the turbine blades. Shroud 40
also includes an outer discharge area 48 which communicates with a
novel collector means shown here as a collector structure 50. A
capture means is disposed interiorly of collector structure 50 and
functions to collect a portion of the gases flowing through the
shroud. This capture means is here shown as a generally
toroidal-shaped capture scoop 52 having an uninterrupted inlet 54.
Inlet 54 is strategically located so that it directly faces the
high velocity region of the gas stream flowing through shroud 40
toward discharge area 48. Inner wall 42 of shroud 40 is provided
with a plurality of injection slots 56 while outer wall 44 is
provided with a plurality of injection slots 58. A first plenum 60
circumscribes a portion of the inner wall 42 of shroud 40 and
functions to feed gases into shroud 40 through injection slots 56.
Similarly, a second plenum 62 circumscribes a portion of the outer
wall 44 of shroud 40 and functions to feed gases into the shroud 40
via injection slots 58. As indicated in FIG. 1, each of the
injection slots 56 and 58 are constructed so as to have a sharp
trailing edge 56a and 58a respectively for introducing a thin sheet
of fluid tangential to the respective inner and outer walls of the
shroud and into the boundary layer fluid for the purpose of
preventing the detachment of the gas stream from the wall.
[0017] Interconnecting first plenum 60 with toroidal structure 52
is at least a first tube or conduit 66. Interconnecting second
plenum 62 with toroidal structure 52 is at least one second tube or
conduit 68. With this novel construction conduit 66 supplies gases
collected through opening 54b of toroidal structure 52 to injection
slots 56 while conduit 68 supplies gases collected through opening
54c of the toroidal structure to injection slots 58. Exhaust gas
from collector 50 is exhausted to atmosphere through an exhaust
stack 70.
[0018] Turning to FIG. 2 of the drawings, this drawing shows the
structural elements that formed a part of the prior art diffuser
structure, but were, for sake of clarity, eliminated from FIG. 1 of
the '605 patent. These important structural elements, which in the
prior art apparatus functioned to maintain rigid concentricity,
comprise a plurality of radial struts "RS" (typically five or six
in number) that interconnect the outer wall of shroud 40 to a
stationary hub generally identified as "SH" via an inner ring "IR".
Also forming a part of the prior art diffuser structure, but were,
for sake of clarity, eliminated from FIG. 1 of the '605 patent is
an outer ring "OR".
[0019] As illustrated in FIG. 2, the radial struts "RS" are
directly in the path of the gas flowing between the last turbine
blade 39 and the first slots 56 and 58 of the diffuser and present
an undesired obstruction to the free flow of the gas. More
particularly, in the prior art construction illustrated in FIG. 2
of the drawings each radial strut "RS" creates a turbulent wake in
which the stagnation pressure of the flow is reduced by a loss of
momentum, thereby reducing the pressure recovery otherwise
obtainable by the diffuser. In an attempt to reduce the swirl of
the gas imparted to the radial struts by the last rotating blades,
the radial struts in the prior art apparatus are sometimes
configured to have an airfoil profile, similar to that of a stator
blade. However, this approach works only at one point of RPM and
load combination and for other RPM and load combinations the swirl
is only partially removed generally at the cost of increased
turbulence. In a conventional prior art diffuser the kinetic energy
of the swirling gas is wasted and although the airfoil
cross-section of the struts attempts to redirect at least part of
the swirling gas in an axial direction, this approach succeeds only
for a particular combination of load and RPM and, even in this case
the wakes and turbulence limit the associated pressure
recovery.
[0020] The diffuser illustrated and described in incorporated by
reference Patent No. '605 re-directs the axial flow in a radial
direction where any swirl present in the flow provides an added
centrifugal pressure increment, regardless of the direction of the
swirl. In this instance, there is no need to attempt to remove the
swirl, since the diffuser itself converts the kinetic energy of the
swirl into a greater pressure increment. However, as previously
mentioned, the presence of the radial struts in the prior art
apparatus, which are necessary for mechanical support, are
detrimental to the pressure recovery by the diffuser.
[0021] The thrust of the present invention is to overcome this
undesirable feature of the prior art apparatus and in so doing
markedly improve the performance of the diffuser without adversely
affecting the mechanical performance of the turbine. As will be
discussed more fully in the paragraphs which follow, this is
accomplished by modifying the prior art structure to, among other
things, eliminate the struts "RS".
[0022] Turning now to FIG. 3 of the drawings, one form of the
improved apparatus of the present invention is there shown and
generally designated by the numeral 100. This apparatus is similar
in some respects to the prior art apparatus shown in FIG. 1 of the
drawings and like numbers are used in FIGS. 1 and 2 to identify
like components. As indicated in FIG. 3, the shaft that was
designated in FIGS. 1 and 2 by the numeral 36 has been removed from
the drawing, since the same diffuser structure is equally usable in
connection with a turbine having a power takeoff shaft that
protrudes from the opposite, or compressor end (see column 4, line
65 of the incorporated by reference '605 patent). Stationary hub
"SH" houses bearings that are precisely concentric with the outer
structures of the turbine and function to support the rotating
parts of the turbine.
[0023] As is also shown in FIG. 3 of the drawings, the improved
apparatus 100 here comprises combination conduit and structural
support members 102 and 104 that take the place of the prior art
conduits 66 and 68 and combination plenum and structural support
members 106 and 108 that take the place of plenums 60 and 62. As
indicated in FIG. 3, combination conduit and structural support
member 102 and 104 function to provide rigidity to the diffuser, to
maintain concentricity between hub "SH" and shrouds 40 and 42
during operation and to direct a portion of the high velocity gas
stream captured by said capture means toward the injector slots
provided in said inner wall of the shroud. Conduits 102 and 104, as
well as plenums 106 and 108, have relatively thick sidewalls which,
unlike the prior art conduits and plenums (which provided only gas
pressure containment) function to provide substantial structural
support to the diffuser. Accordingly, in the improved apparatus of
the invention, the combination conduit and structural support
members 102 and 104 and the combination plenum and structural
support members 106 and 108 comprise load bearing structures as
well as comprising structures for conveying gas from capture scoop
52 to slots 56 and 58.
[0024] Also forming a part of the improved apparatus 100 are
substantially larger structural rings 110 and 112 that take the
place of the prior art rings "IR" and "OR". As shown in FIG. 3 of
the drawings, structural rings 110 and 112 circumscribe and are
connected to stationary hub "SH". Additionally, the wall thickness
of the generally toroidal-shaped capture scoop 52, which is
designated in FIG. 3 by the numeral 114 has been substantially
increased. With the construction thus described, combination plenum
and structural support member 106 carries the stress from
combination conduit and structural support member 102 to structural
ring 110 which distributes the stress to the area of shroud 40
where former struts "RS" were previously anchored. Similarly,
combination plenum and structural support member 108 carries the
stress from combination conduit and structural support member 104
to structural ring 112, which distributes the stress to, and
supports stationary hub "SH" as was previously done by struts
"RS".
[0025] The details of the design of load-bearing structures, such
as combination conduit and structural support members 102 and 104
and combination plenum and structural support members 106 and 108,
are well known in the art of mechanical design and involve careful
consideration of the moment of inertia of the cross-sections, the
modulus of elasticity of the material, and the overall curvature of
the structures. In addition, the designer must take into
consideration the differential thermal expansion coefficients
required by the different temperatures of the gas flowing within
the structure. No further discussion of the structural design is
here required beyond emphasizing that the reinforced portion of the
diffuser structure, including novel members 102, 104, 106 and 108,
must be designed to maintain the required concentricity between
stationary hub "SH" and shroud 40 under all operating
conditions.
[0026] Alternate approaches to improving the performance of the
diffuser without adversely effecting the mechanical performance of
the turbine comprise adding the reinforcing structure directly to
conduits 66 and 68 as described in connection with the embodiment
of FIG. 3 and partially separating the load-carrying structure from
the gas conveying structures in order to derive the maximum
advantage from the geometry of the combined elements. One such
approach is shown in FIG. 4, which comprises a partial external
view of the reinforcing structure superimposed on the
cross-sectional view of the improved diffuser, noting that the
re-enforcements are mounted externally to collector structure 50
and join reinforced members 102 and 104 as shown.
[0027] In this case a first generally vertically extending
reinforcement plate or built-up structural member 116, that is
located in the vertical plane of symmetry of the diffuser can be
connected to reinforced member 102 and extended to a
ground-engaging plate 118 and can be used to support the weight of
the diffuser as well as the weight of the exit section of the
turbine. In this alternate embodiment, other reinforcements can be
placed to the side to insure rigidity in the transverse plane. For
example, a second reinforcement plate or built-up structure 120,
which is operably associated with first generally vertically
extending reinforcement plate 118, can be connected to reinforced
member 102 in the manner shown in FIG. 4 of the drawings.
[0028] A mandatory requirement is that the rigidity combined with
the mass of the supported elements results in a resonant frequency
far from the operating RPM and its harmonics. This requirement
dictates the number of reinforcing structures 120 and their
location around the diffuser, with suitable spacing between them to
accommodate the passage of exhaust stack 70.
[0029] Having now described the invention in detail in accordance
with the requirements of the patent statutes, those skilled in this
art will have no difficulty in making changes and modifications in
the individual parts or their relative assembly in order to meet
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.
* * * * *