U.S. patent application number 15/070093 was filed with the patent office on 2017-09-21 for axially staged fuel injector assembly mounting.
The applicant listed for this patent is General Electric Company. Invention is credited to David William Cihlar, Jonathan Hale Kegley, Jonathan Glenn Reed, Christopher Paul Willis.
Application Number | 20170268783 15/070093 |
Document ID | / |
Family ID | 58265869 |
Filed Date | 2017-09-21 |
United States Patent
Application |
20170268783 |
Kind Code |
A1 |
Cihlar; David William ; et
al. |
September 21, 2017 |
AXIALLY STAGED FUEL INJECTOR ASSEMBLY MOUNTING
Abstract
The present disclosure is directed to a system for mounting an
axially staged fuel injector assembly. The system includes an
annularly shaped liner that at least partially defines a hot gas
path of a combustor. The liner defines an injector opening that
extends radially through the liner. A flow sleeve circumferentially
surrounds at least a portion of the liner and is radially spaced
from the liner to form a cooling flow annulus therebetween. An
annular injector boss extends radially from the liner through the
flow sleeve. The injector boss includes a first end portion that
extends circumferentially about the injector opening and a second
end portion that is disposed radially outwardly from an outer
surface of the flow sleeve. The injector boss is formed to receive
a fuel injector. The present disclosure is also directed to a
method for mounting an axially staged fuel injector.
Inventors: |
Cihlar; David William;
(Greenville, SC) ; Kegley; Jonathan Hale; (Greer,
SC) ; Willis; Christopher Paul; (Liberty, SC)
; Reed; Jonathan Glenn; (Greer, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
58265869 |
Appl. No.: |
15/070093 |
Filed: |
March 15, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23R 3/002 20130101;
F23R 3/46 20130101; F23R 3/346 20130101; F23R 3/283 20130101 |
International
Class: |
F23R 3/34 20060101
F23R003/34; F23R 3/28 20060101 F23R003/28; F23R 3/00 20060101
F23R003/00 |
Claims
1. A system for mounting an axially staged fuel injector,
comprising: an annularly shaped liner at least partially defining a
hot gas path of a combustor, wherein the liner defines an injector
opening that extends radially through the liner; a flow sleeve
circumferentially surrounding at least a portion of the liner,
wherein the flow sleeve is radially spaced from the liner to form a
cooling flow annulus therebetween; and an annular injector boss
extending radially from the liner through the flow sleeve, the
injector boss having a first end portion that extends
circumferentially about the injector opening and a second end
portion disposed radially outwardly from an outer surface of the
flow sleeve, wherein the injector boss is formed to receive a fuel
injector.
2. The system as in claim 1, further comprising a support plate
disposed radially outwardly from the outer surface of the flow
sleeve, wherein the support plate extends circumferentially around
the injector boss, wherein the support plate includes an inner
portion that extends into a slot defined by the injector boss.
3. The system as in claim 2, wherein the support plate comprises a
first plate and a second plate, wherein an inner portion of the
first plate and an inner portion of the second plate extend within
the slot defined by the injector boss.
4. The system as in claim 2, further comprising a doubled ended
stud, wherein a first end of the double ended stud is threadingly
engaged with the support plate and a second end of the doubled
ended stud extends radially through a mounting hole defined by the
fuel injector.
5. The system as in claim 2, further comprising a support plate cap
having an inner side, an outer side and a pocket defined along the
inner side, wherein at least a portion of the support plate is
seated within the pocket.
6. The system as in claim 5, wherein the support plate cap is
fixedly connected to the flow sleeve.
7. The system as in claim 5, wherein the support plate cap is
sealed against the outer surface of the flow sleeve.
8. The system as claim 5, wherein the support plate cap defines a
plurality of fastener holes, wherein each fastener hole is
coaxially aligned with a respective fastener opening defined by the
support plate and a mounting hole defined by the axially staged
fuel injector.
9. The system as in claim 5, further comprising a doubled ended
stud that extends from the support plate through the support cover
and through a mounting hole defined by the fuel injector, wherein a
first end of the double ended stud is threadingly engaged with the
support plate and a second end of the doubled ended stud is
threadingly engaged with a nut.
10. A system for mounting an axially staged fuel injector,
comprising: an annularly shaped liner at least partially defining a
hot gas path of a combustor, wherein the liner defines a injector
boss opening that extends radially through the liner; a flow sleeve
circumferentially surrounding at least a portion of the liner,
wherein the flow sleeve is radially spaced from the liner to form a
cooling flow annulus therebetween; and an annular injector boss
coaxially aligned with the injector opening and extending radially
from the liner through the flow sleeve, the injector boss having a
first end portion fixedly connected to the liner and a second end
portion disposed radially outwardly from an outer surface of the
flow sleeve, wherein the injector boss is formed to receive a fuel
injector.
11. The system as in claim 10, further comprising a support plate
disposed radially outwardly from the outer surface of the flow
sleeve, wherein the support plate extends circumferentially around
the injector boss, wherein the support plate includes an inner
portion that extends into a slot defined by the injector boss.
12. The system as in claim 11, wherein the support plate comprises
a first plate and a second plate, wherein an inner portion of the
first plate and an inner portion of the second plate extend within
the slot defined by the injector boss.
13. The system as in claim 11, further comprising a doubled ended
stud, wherein a first end of the double ended stud is threadingly
engaged with the support plate and a second end of the doubled
ended stud extends radially through a mounting hole defined by the
fuel injector.
14. The system as in claim 11, further comprising a support plate
cap having an inner side, an outer side and a pocket defined along
the inner side, wherein at least a portion of the support plate is
seated within the pocket.
15. The system as in claim 14, wherein the support plate cap is
fixedly connected to the flow sleeve.
16. The system as in claim 15, wherein the support plate cap is
sealed against the outer surface of the flow sleeve.
17. The system as claim 15, wherein the support plate cap defines a
plurality of fastener holes, wherein each fastener hole is
coaxially aligned with a respective fastener opening defined by the
support plate and a mounting hole defined by the axially staged
fuel injector.
18. The system as in claim 15, further comprising a doubled ended
stud that extends from the support plate through the support cover
and through a mounting hole defined by the fuel injector, wherein a
first end of the double ended stud is threadingly engaged with the
support plate and a second end of the doubled ended stud is
threadingly engaged with a nut.
19. A method for mounting an axially staged fuel injector,
comprising: inserting a support plate into a slot defined along a
side wall of a second end portion of an injector boss, wherein the
second end portion is disposed radially outwardly from an outer
surface of the flow sleeve; placing a support plate cap over the
support plate; threading a first end of a double ended stud into a
fastener opening defined by the support plate, wherein the double
ended stud extends through the support plate cap; inserting a fuel
injector into the injector boss, wherein a second end of the double
ended stud extends through a mounting hole defined by the fuel
injector; and securing the fuel injector to the support plate cap
via a nut threadingly engaged with the second end of the double
ended stud.
Description
FIELD OF THE TECHNOLOGY
[0001] The subject matter disclosed herein relates to a combustor
for a gas turbine. More specifically, the disclosure is directed to
a system and method for mounting an axially staged fuel injector
assembly of a gas turbine combustor.
BACKGROUND
[0002] Gas turbines usually burn hydrocarbon fuels and produce air
polluting emissions such as oxides of nitrogen (NOx) and carbon
monoxide (CO). Oxidization of molecular nitrogen in the gas turbine
depends upon the temperature of gas located in a combustor, as well
as the residence time for reactants located in the highest
temperature regions within the combustor. Thus, the amount of NOx
produced by the gas turbine may be reduced by either maintaining
the combustor temperature below a temperature at which NOx is
produced, or by limiting the residence time of the reactant in the
combustor.
[0003] One approach for controlling the temperature of the
combustor involves pre-mixing fuel and air to create a lean
fuel-air mixture prior to combustion. This approach may include the
axial staging of fuel injection where a first fuel-air mixture is
injected and ignited at a first or primary combustion zone of the
combustor to produce a main flow of high energy combustion gases,
and where a second fuel-air mixture is injected into and mixed with
the main flow of high energy combustion gases via a plurality of
radially oriented and circumferentially spaced fuel injectors or
axially staged fuel injector assemblies positioned downstream from
the primary combustion zone. Axially staged injection increases the
likelihood of complete combustion of available fuel, which in turn
reduces the air polluting emissions.
[0004] During operation of the combustor, it is necessary to cool
one or more liners or ducts that form a combustion chamber and/or a
hot gas path through the combustor. Liner cooling is typically
achieved by routing a cooling medium such as the compressed air
through a cooling flow annulus or flow passage defined between the
liner and a flow sleeve and/or an impingement sleeve that surrounds
the liner. However, in particular configurations, hardware for
mounting the axially staged fuel injector assemblies creates a flow
blockage or obstruction within the cooling flow annulus, thereby
disrupting the cooling flow through the cooling flow annulus. This
disruption in the cooling flow annulus may result in reduced
pressure of the cooling medium at a head end portion of the
combustor and/or reduced cooling effectiveness of the cooling
medium within the cooling flow annulus, particularly downstream
from the mounting hardware.
BRIEF DESCRIPTION OF THE TECHNOLOGY
[0005] Aspects and advantages are set forth below in the following
description, or may be obvious from the description, or may be
learned through practice.
[0006] One embodiment of the present disclosure is directed to a
system for mounting an axially staged fuel injector. The system
includes an annularly shaped liner that at least partially defines
a hot gas path of a combustor. The liner defines an injector
opening that extends radially through the liner. A flow sleeve
circumferentially surrounds at least a portion of the liner and is
radially spaced from the liner to form a cooling flow annulus
therebetween. An annular injector boss extends radially from the
liner through the flow sleeve. The injector boss includes a first
end portion that extends circumferentially about the injector
opening and a second end portion that is disposed radially
outwardly from an outer surface of the flow sleeve. The injector
boss is formed to receive a fuel injector.
[0007] Another embodiment of the present disclosure is directed to
a system for mounting an axially staged fuel injector. The system
includes an annularly shaped liner that at least partially defines
a hot gas path of a combustor. The liner defines a injector boss
opening that extends radially through the liner. A flow sleeve
circumferentially surrounds at least a portion of the liner. The
flow sleeve is radially spaced from the liner to form a cooling
flow annulus therebetween. An annular injector boss is coaxially
aligned with the injector opening and extends radially from the
liner through the flow sleeve. The injector boss has a first end
portion that is fixedly connected to the liner and a second end
portion disposed radially outwardly from an outer surface of the
flow sleeve. The injector boss is formed to receive a fuel
injector.
[0008] Another embodiment includes a method for mounting an axially
staged fuel injector. The method includes inserting a support plate
into a slot defined along a side wall of a second end portion of an
injector boss where the second end portion is disposed radially
outwardly from an outer surface of the flow sleeve, placing a
support plate cap over the support plate, threading a first end of
a double ended stud into a fastener opening defined by the support
plate where the double ended stud extends through the support plate
cap and inserting a fuel injector into the injector boss where a
second end of the double ended stud extends through a mounting hole
defined by the fuel injector. The method further includes securing
the fuel injector to the support plate cap via a nut that is
threadingly engaged with the second end of the double ended
stud.
[0009] Those of ordinary skill in the art will better appreciate
the features and aspects of such embodiments, and others, upon
review of the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A full and enabling disclosure of the of various
embodiments, including the best mode thereof to one skilled in the
art, is set forth more particularly in the remainder of the
specification, including reference to the accompanying figures, in
which:
[0011] FIG. 1 is a functional block diagram of an exemplary gas
turbine that may incorporate various embodiments of the present
disclosure;
[0012] FIG. 2 is a simplified cross-section side view of an
exemplary combustor as may incorporate various embodiments of the
present disclosure;
[0013] FIG. 3 provides an exploded perspective view of a portion of
the combustor including a system for mounting an axially staged
fuel injector according to at least one embodiment of the present
disclosure;
[0014] FIG. 4 provides an assembled cross sectional upstream view
of the system as shown in FIG. 3, according to at least one
embodiment of the present disclosure;
[0015] FIG. 5 provides a top view of a portion of the system as
shown in FIGS. 3 and 4, according to at least one embodiment of the
present disclosure; and
[0016] FIG. 6 provides a block diagram of a method for mounting an
axially staged fuel injector according to at least one embodiment
of the present disclosure.
DETAILED DESCRIPTION
[0017] Reference will now be made in detail to present embodiments
of the disclosure, one or more examples of which are illustrated in
the accompanying drawings. The detailed description uses numerical
and letter designations to refer to features in the drawings. Like
or similar designations in the drawings and description have been
used to refer to like or similar parts of the disclosure.
[0018] As used herein, the terms "first", "second", and "third" may
be used interchangeably to distinguish one component from another
and are not intended to signify location or importance of the
individual components. The terms "upstream" and "downstream" refer
to the relative direction with respect to fluid flow in a fluid
pathway. For example, "upstream" refers to the direction from which
the fluid flows, and "downstream" refers to the direction to which
the fluid flows. The term "radially" refers to the relative
direction that is substantially perpendicular to an axial
centerline of a particular component, the term "axially" refers to
the relative direction that is substantially parallel and/or
coaxially aligned to an axial centerline of a particular component
and the term "circumferentially" refers to the relative direction
that extends around the axial centerline of a particular
component.
[0019] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting. As
used herein, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises" and/or "comprising," when used in this specification,
specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0020] Each example is provided by way of explanation, not
limitation. In fact, it will be apparent to those skilled in the
art that modifications and variations can be made without departing
from the scope or spirit thereof. For instance, features
illustrated or described as part of one embodiment may be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present disclosure covers such modifications and
variations as come within the scope of the appended claims and
their equivalents. Although exemplary embodiments of the present
disclosure will be described generally in the context of a
combustor for a land based power generating gas turbine combustor
for purposes of illustration, one of ordinary skill in the art will
readily appreciate that embodiments of the present disclosure may
be applied to any style or type of combustor for a turbomachine and
are not limited to combustors or combustion systems for land based
power generating gas turbines unless specifically recited in the
claims.
[0021] Referring now to the drawings, FIG. 1 illustrates a
schematic diagram of an exemplary gas turbine 10. The gas turbine
10 generally includes an inlet section 12, a compressor 14 disposed
downstream of the inlet section 12, at least one combustor 16
disposed downstream of the compressor 14, a turbine 18 disposed
downstream of the combustor 16 and an exhaust section 20 disposed
downstream of the turbine 18. Additionally, the gas turbine 10 may
include one or more shafts 22 that couple the compressor 14 to the
turbine 18.
[0022] During operation, air 24 flows through the inlet section 12
and into the compressor 14 where the air 24 is progressively
compressed, thus providing compressed air 26 to the combustor 16.
At least a portion of the compressed air 26 is mixed with a fuel 28
within the combustor 16 and burned to produce combustion gases 30.
The combustion gases 30 flow from the combustor 16 into the turbine
18, wherein energy (kinetic and/or thermal) is transferred from the
combustion gases 30 to rotor blades (not shown), thus causing shaft
22 to rotate. The mechanical rotational energy may then be used for
various purposes such as to power the compressor 14 and/or to
generate electricity. The combustion gases 30 exiting the turbine
18 may then be exhausted from the gas turbine 10 via the exhaust
section 20.
[0023] As shown in FIG. 2, the combustor 16 may be at least
partially surrounded an outer casing 32 such as a compressor
discharge casing. The outer casing 32 may at least partially define
a high pressure plenum 34 that at least partially surrounds various
components of the combustor 16. The high pressure plenum 34 may be
in fluid communication with the compressor 14 (FIG. 1) so as to
receive the compressed air 26 therefrom. An end cover 36 may be
coupled to the outer casing 32. In particular embodiments, the
outer casing 32 and the end cover 36 may at least partially define
a head end volume or portion 38 of the combustor 16. In particular
embodiments, the head end portion 38 is in fluid communication with
the high pressure plenum 34 and/or the compressor 14.
[0024] Fuel nozzles 40 extend axially downstream from the end cover
36. One or more annularly shaped liners or ducts 42 may at least
partially define a primary or first combustion or reaction zone 44
for combusting the first fuel-air mixture and/or may at least
partially define a secondary combustion or reaction zone 46 formed
axially downstream from the first combustion zone 44 with respect
to an axial centerline 48 of the combustor 16. The liner 42 at
least partially defines a hot gas path 50 from the primary fuel
nozzle(s) 40 to an inlet 52 of the turbine 18 (FIG. 1). In at least
one embodiment, the liner 42 may be formed so as to include a
tapering or transition portion. In particular embodiments, the
liner 42 may be formed from a singular or continuous body. A flow
sleeve 54 circumferentially surrounds at least a portion of the
liner 42. The flow sleeve 54 is radially spaced from the liner 42
to form a cooling flow annulus 56 therebetween.
[0025] In at least one embodiment, the combustor 16 includes an
axially staged fuel injection system 58. The axially staged fuel
injection system 58 includes at least one fuel injector or fuel
injector assembly 60 axially staged or spaced from the primary fuel
nozzle(s) 40 with respect to axial centerline 48. The fuel injector
60 is disposed downstream of the primary fuel nozzle(s) 40 and
upstream of the inlet 52 to the turbine 18. It is contemplated that
a number of fuel injectors 60 (including two, three, four, five, or
more fuel injector assemblies 60) may be used in a single combustor
16.
[0026] In various embodiments, a system for mounting the axially
staged fuel injector(s) 60, herein referred to as "system" is
provided. FIG. 3 provides an exploded perspective view of a portion
of the combustor 16 including the system 100 according to at least
one embodiment of the present disclosure. FIG. 4 provides an
assembled cross sectional upstream view of the system 100 as shown
in FIG. 3, according to at least one embodiment of the present
disclosure. FIG. 5 provides a top view of a portion of the system
100 as shown in FIGS. 3 and 4 according to at least one embodiment
of the present disclosure.
[0027] In at least one embodiment, as shown in FIGS. 3 and 4
collectively, the system 100 includes the annularly shaped liner
42. As shown in FIG. 4, the liner 42 defines an injector opening
102 that extends radially through the liner 42. The flow sleeve 54
circumferentially surrounds at least a portion of the liner 42 and
the cooling flow annulus 56 is formed radially therebetween. As
shown in FIGS. 3 and 4, an annular injector boss 104 extends
radially from the liner 42 through the flow sleeve 54. The injector
boss 104 is formed to receive a portion of the fuel injector 60.
The injector boss 104 has a first end portion 106 (FIG. 4) that
extends circumferentially about the injector opening 102. The first
end portion 106 may partially define the hot gas path 50 (FIG. 2).
As shown in FIGS. 3 and 4, the injector boss 104 includes a second
end portion 108 that is disposed radially outwardly from an outer
surface 62 of the flow sleeve 54.
[0028] In particular embodiments, as shown in FIGS. 3 and 4 the
injector boss 104 at least partially defines a slot or groove 110.
In at least one embodiment, the slot 110 may be defined along a
side wall 112 of the injector boss 104 proximate to the second end
portion 108. The slot 110 may extend circumferentially about the
injector boss 104 within and/or along the side wall 112. In various
embodiments, the slot 110 is positioned radially outward from the
outer surface 62 of the flow sleeve 54.
[0029] In at least one embodiment, as shown in FIGS. 3 and 4
collectively, the system 100 includes a support plate 114 disposed
radially outwardly from the outer surface 62 of the flow sleeve 54.
The support plate 114 extends circumferentially at least partially
around the injector boss 104. As shown in FIG. 4, the support plate
114 includes an inner portion or surface 116 that extends into the
slot 110 defined by the injector boss 104.
[0030] In at least one embodiment, as shown in FIG. 3, the support
plate 114 is made up of multiple plates formed to wrap around the
injector boss and/or extend into the slot 110. For example, as
shown in FIG. 3, the support plate 114 may comprise a first plate
114(a) and a second plate 114(b). Each of the first plate 114(a)
and the second plate 114(b) may include a respective inner surface
or portion 116(a), 116(b) which extends within the slot 110. The
inner surface 116(a), 116(b) may be generally arcuate.
[0031] In at least one embodiment, as shown in FIGS. 3 and 4, one
or more of the support plate 114 or support plates 114(a), 114(b)
define one or more fastener openings 118 along a top side 120 of
the respective support plate 114, 114(a), 114(b). In particular
embodiments, one or more fastener openings 118 may be threaded or
may include a threaded insert 122 (FIG. 4) for receiving a threaded
fastener.
[0032] In at least one embodiment, as shown in FIGS. 3 and 4
collectively, the system 100 may include a support plate cap 124.
As shown in FIG. 4, the support plate cap 124 includes an inner
side 126, an outer side 128 and a pocket or void 130 defined along
the inner side 126. At least a portion of the support plate 104 may
be seated or disposed within the pocket 130.
[0033] In particular embodiments, the support plate cap 124 is
fixedly connected to the flow sleeve 54. For example, as shown in
FIG. 5, the support plate cap 124 may be bolted or otherwise
fastened or attached to the flow sleeve 54 via one or more
fasteners 132. In particular embodiments, the support plate cap 124
is sealed against the outer surface 62 of the flow sleeve 54.
[0034] In particular embodiments, as shown in FIGS. 3 and 4, the
support plate cap 124 defines a plurality of fastener holes 134
coaxially aligned with a respective fastener opening 118 defined by
the support plate 114 and a respective mounting hole 136 defined by
the axially staged fuel injector 60. In at least one embodiment, as
shown in FIGS. 3, 4 and 5 collectively, at least one doubled ended
stud 138 may be used to secure or attach the support plate cap 124
to the support plate 114. As shown in FIG. 4, a first end portion
140 of the double ended stud 138 is threadingly engaged with the
support plate 114 for example via the threaded insert 122 and a
second end portion 142 of the doubled ended stud 138 extends
radially through a respective mounting hole 136 defined by the fuel
injector 60.
[0035] In particular embodiments, as shown in FIGS. 3, 4 and 5
collectively, at least one doubled ended stud 138 extends from the
support plate 114 through a respective fastener hole 134 of the
support plate cap 124 and through a respective mounting hole 136
defined by the fuel injector 60. The first end 140 of the double
ended stud 138 is threadingly engaged with the support plate 114
and the second end 142 of the doubled ended stud 138 is threadingly
engaged with a nut 144.
[0036] The various embodiments described and illustrated herein
provide a method 200 for mounting an axially staged fuel injector
60. FIG. 6 provides a block diagram of method 200 according to one
embodiment of the present disclosure. As shown in FIG. 6 at step
202, method 200 includes inserting the support plate 114 and/or
supports plates 114(a), 114(b) into the slot 110 defined along the
side wall 112 of the second end portion 108 of the injector boss
104 where the second end portion 108 is disposed radially outwardly
from the outer surface 62 of the flow sleeve 54. At step 204,
method 200 includes placing the support plate cap 124 over the
support plate 114. At step 206, method 200 includes threading the
first end 140 of a respective double ended stud 138 into a
respective fastener opening 118 defined by the support plate 114
where the double ended stud 138 extends through the support plate
cap 124. At step 208, method 200 includes inserting the fuel
injector 60 into the injector boss 104 where the second end 142 of
the double ended stud 138 extends through a respective mounting
hole 136 defined by the fuel injector 62. At step 210, method 200
includes securing or attaching the fuel injector 60 to the support
plate cap 124 via a nut 144 threadingly engaged with the second end
142 of the double ended stud 138.
[0037] The various embodiment of the system for mounting axially
staged fuel injectors 100 described and illustrated herein provide
various technical benefits over existing mounting configurations.
For example, by positioning the various mounting components such as
the support plate 114, the support plate cap 124, the double ended
studs 138 and the portion of the injector boss 104 that engages
with these components flow obstructions within the cooling flow
annulus are reduced, thereby enhancing cooling of the liner during
operation of the combustor 16. In addition, the system 100 may
reduce assembly and disassembly time for installing and removing
the fuel injectors 60.
[0038] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal language of the claims.
* * * * *