U.S. patent application number 14/190902 was filed with the patent office on 2015-08-27 for exhaust plenum for radial diffuser.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is General Electric Company. Invention is credited to Chengappa Manjunath, Deepesh D. Nanda, Santhosh Kumar Vijayan.
Application Number | 20150240667 14/190902 |
Document ID | / |
Family ID | 53782622 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150240667 |
Kind Code |
A1 |
Nanda; Deepesh D. ; et
al. |
August 27, 2015 |
EXHAUST PLENUM FOR RADIAL DIFFUSER
Abstract
An exhaust gas diffuser for a turbomachine includes a diffuser
supported on a turbine rotor, aligned with an axis of said turbine
rotor. The diffuser is configured to re-direct turbine exhaust gas
substantially ninety degrees from a first direction of flow along
the rotor axis. A plenum chamber is in fluid communication with and
surrounds an outlet end of the diffuser. The plenum chamber is in
fluid communication with a transition duct adapted to supply the
exhaust gas to another turbomachine. The plenum chamber expands in
volume between the diffuser and the transition duct.
Inventors: |
Nanda; Deepesh D.;
(Bangalore, IN) ; Vijayan; Santhosh Kumar;
(Bangalore, IN) ; Manjunath; Chengappa;
(Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
53782622 |
Appl. No.: |
14/190902 |
Filed: |
February 26, 2014 |
Current U.S.
Class: |
60/39.182 ;
415/207 |
Current CPC
Class: |
F05D 2250/324 20130101;
F01K 23/10 20130101; Y02E 20/16 20130101; F01D 25/30 20130101 |
International
Class: |
F01K 23/10 20060101
F01K023/10; F01D 25/30 20060101 F01D025/30 |
Claims
1. An exhaust gas diffuser for a turbomachine comprising: a
diffuser supported in a turbine rotor, aligned with an axis of said
turbine rotor, said diffuser configured to re-direct turbine
exhaust gas substantially ninety degrees from a first direction of
flow along said axis; a plenum chamber in fluid communication with
and surrounding an outlet end of said diffuser, said plenum chamber
in fluid communication with a transition duct adapted to supply the
exhaust gas to another turbomachine; wherein said plenum chamber
expands in volume in a direction toward said transition duct.
2. The exhaust gas diffuser of claim 1 wherein said plenum chamber
is comprised in part of a pair of non-parallel side walls and a
peripheral edge wall connecting said pair of non-parallel side
walls.
3. The exhaust gas diffuser of claim 2 wherein one of said pair of
non-parallel side walls is substantially perpendicular to said
axis.
4. The exhaust gas diffuser of claim 3 wherein the other of said
pair of non-parallel side walls extends at an angle of
20-50.degree. relative to said one of said non-parallel side
walls.
5. The exhaust gas diffuser of claim 3 wherein the other of said
pair of non-parallel side walls extends at an angle of
35-45.degree. relative to said one of said non-parallel side
walls.
6. The exhaust gas diffuser of claim 2 wherein said peripheral edge
wall comprises a radiused end portion connecting to a pair of
straight, substantially parallel top and bottom wall portions.
7. The exhaust gas diffuser of claim 6 wherein said radiused end
portion lies on one side of said axis and said pair of straight,
substantially parallel top and bottom wall portions cross said
axis, connecting to said transition duct on an opposite side of
said axis.
8. The exhaust gas diffuser of claim 7 wherein the other of said
pair of non-parallel side walls extends at an angle of
20-50.degree. relative to said one of said non-parallel side
walls.
9. The exhaust gas diffuser of claim 7 wherein the other of said
pair of non-parallel side walls extends at an angle of
35-45.degree. relative to said one of said non-parallel side
walls.
10. A turbomachine comprising: a gas turbine section including a
turbine rotor; a radial diffuser disposed along a first axis of
said turbine rotor; an exhaust plenum comprising an inlet receiving
a portion of the radial diffuser, said exhaust plenum extending
along a second axis substantially perpendicular to said first axis,
said plenum chamber expanding in volume along said second axis.
11. The turbomachine of claim 1 wherein said plenum chamber is
comprised in part of a pair of non-parallel side walls an a
peripheral edge wall connecting said pair of non-parallel side
walls.
12. The turbomachine of claim 11 wherein one of said pair of
non-parallel side walls is substantially perpendicular to said
axis.
13. The turbomachine of claim 12 wherein the other of said pair of
non-parallel side walls extends at an angle of 20-50.degree.
relative to said one of said non-parallel side walls.
14. The turbomachine of claim 12 wherein the other of said pair of
non-parallel side walls extends at an angle of 35-45.degree.
relative to said one of said non-parallel side walls.
15. The turbomachine of claim 11 wherein said peripheral edge wall
comprises a radiused end portion connecting to a pair of straight,
substantially parallel top and bottom wall portions.
16. The turbomachine of claim 15 wherein said radiused end portion
lies on one side of said axis and said pair of straight,
substantially parallel top and bottom wall portions cross said
axis, connecting to said transition duct on an opposite side of
said axis.
17. A combined cycle system comprising: a gas turbine including a
turbine rotor extending along a first axis; a heat recovery steam
generator; a steam turbine adapted to receive steam from said heat
recovery steam generator; a radial diffuser disposed along said
first axis; and an exhaust plenum comprising an inlet receiving a
portion of the radial diffuser, said exhaust plenum extending along
a second axis substantially perpendicular to said first axis, said
plenum chamber expanding in volume along said second axis and
communicating with said heat recovery steam generator.
18. A combined cycle system of claim 17 wherein said plenum chamber
is comprised in part of a pair of non-parallel side walls an a
peripheral edge wall connecting said pair of non-parallel side
walls and wherein one of said pair of non-parallel side walls is
substantially perpendicular to said axis.
19. A combined cycle system of claim 18 wherein the other of said
pair of non-parallel side walls extends at an angle of
20-50.degree. relative to said one of said non-parallel side
walls.
20. A combined cycle system of claim 18 wherein the other of said
pair of non-parallel side walls extends at an angle of
35-45.degree. relative to said one of said non-parallel side walls.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to integrating heat
recovery steam generation (HRSG) systems with gas turbine exhaust
components, and more specifically, to a turbine exhaust gas plenum
designed to promote uniform flow of combustion gases into the
HRSG.
[0002] In combined cycle power generation systems, heated exhaust
gas discharged from gas turbines may be used by HRSG systems as a
source of heat which may be transferred to a water source to
generate superheated steam. In turn, the superheated steam may be
used within steam turbines as a source of power. The heated exhaust
gas from a gas turbine may be delivered to the HRSG system through,
among other things, an exhaust plenum and diffuser, which may help
convert the kinetic energy of the heated exhaust gas exiting the
last stage of the gas turbine into potential energy in the form of
increased static pressure. Once delivered to the HRSG system, the
heated exhaust gas may traverse a series of heat exchanger
elements, such as superheaters, re-heaters, evaporators,
economizers, and so forth. The heat exchanger elements may be used
to transfer heat from the heated exhaust gas to the water source to
generate superheated steam. It is a design objective to promote
uniform flow through the exhaust gas plenum without negatively
impacting diffuser performance, i.e., enabling flow diffusion
without appreciable total pressure loss.
BRIEF DESCRIPTION OF THE INVENTION
[0003] In one embodiment, there is provided an exhaust gas diffuser
for a turbomachine comprising a diffuser supported in a turbine
rotor, aligned with an axis of the turbine rotor, the diffuser
configured to re-direct turbine exhaust gas substantially ninety
degrees from a first direction of flow along the axis; a plenum
chamber in fluid communication with and surrounding an outlet end
of the diffuser, the plenum chamber in fluid communication with a
transition duct adapted to supply the exhaust gas to another
turbomachine; wherein the plenum chamber expands in volume in a
direction toward the transition duct.
[0004] In another embodiment, there is provided a turbomachine
comprising a gas turbine section including a turbine rotor; a
radial diffuser disposed along a first axis of the turbine rotor;
an exhaust plenum comprising an inlet receiving a portion of the
radial diffuser, the exhaust plenum extending along a second axis
substantially perpendicular to the first axis, the plenum chamber
expanding in volume along the second axis.
[0005] In still another embodiment, there is provided a combined
cycle system comprising: a gas turbine including a turbine rotor
extending along a first axis; a heat recovery steam generator; a
steam turbine adapted to receive steam from the heat recovery steam
generator; a radial diffuser disposed along the first axis; and an
exhaust plenum comprising an inlet receiving a portion of the
radial diffuser, the exhaust plenum extending along a second axis
substantially perpendicular to the first axis, the plenum chamber
expanding in volume along the second axis and communicating with
the heat recovery steam generator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0007] FIG. 1 is a schematic flow diagram of an embodiment of a
combined cycle power generation system having a gas turbine, a
steam turbine, and an HRSG;
[0008] FIG. 2 is a detailed but partial side section view of an
embodiment of the gas turbine of FIG. 1 having heat exchanger
elements of the HRSG of FIG. 1 integrated with components of an
exhaust diffuser of the gas turbine;
[0009] FIG. 3 is a cut-away perspective view of an exhaust gas
plenum of the type which could be employed in the gas turbine of
FIG. 2;
[0010] FIG. 4 is a partially cut-away top view of the exhaust
plenum shown in FIG. 3;
[0011] FIG. 5 is a perspective view of an exhaust gas diffuser and
plenum in accordance with an exemplary but nonlimiting embodiment
of the invention;
[0012] FIG. 6 is another perspective view of the exhaust gas
diffuser and plenum shown in FIG. 5; and
[0013] FIG. 7 is a top plan view of the exhaust gas diffuser and
plenum shown in FIGS. 5 and 6.
[0014] FIG. 8 illustrates HRSG inlet profiles at the plenum exit
and at the downstream edge of the transition section.
DETAILED DESCRIPTION OF THE INVENTION
[0015] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, all features of an actual
implementation may not be described in the specification. It should
be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0016] When introducing elements of various embodiments of the
present invention, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements. Any examples of operating parameters are not
exclusive of other parameters of the disclosed embodiments.
[0017] FIG. 1 is a schematic flow diagram of an embodiment of a
combined cycle power generation system 10 having a gas turbine, a
steam turbine, and an HRSG. Specifically, the system 10 may include
a gas turbine 12 for driving a first load 14. The first load 14 may
be, for instance, an electrical generator for producing electrical
power. The gas turbine 12 may include a turbine 16, a combustor 18,
and a compressor 20. The system 10 may also include a steam turbine
22 for driving a second load 24. The second load 24 may also be an
electrical generator for generating electrical power. It will be
understood, however, that both the first and second loads 14, 24
may be other types of loads capable of being driven by the gas
turbine 12 and steam turbine 22. In addition, although the gas
turbine 12 and steam turbine 22 may drive separate loads 14 and 24,
as shown in the illustrated embodiment, the gas turbine 12 and
steam turbine 22 may also be utilized in tandem to drive a single
load via a single shaft. In the illustrated embodiment, the steam
turbine 22 may include one low-pressure section 26 (LP ST), one
intermediate-pressure section 28 (IP ST), and one high-pressure
section 30 (HP ST). However, the specific configuration of the
steam turbine 22, as well as the gas turbine 12, may be
implementation-specific and may include any combination of sections
and/or stages.
[0018] The system 10 may also include a multi-stage HRSG 32. The
simplified depiction of the HRSG 32 and its components are not
intended to be limiting. Rather, the illustrated HRSG 32 is shown
to convey the general arrangement of such systems. Heated exhaust
gas 34 from the gas turbine 12 may be transported into the HRSG 32
and used to heat steam used to power the steam turbine 22. Exhaust
from the low-pressure section 26 of the steam turbine 22 may be
directed into a condenser 36. Condensate from the condenser 36 may,
in turn, be directed into a low-pressure section of the HRSG 32
with the aid of a condensate pump 38.
[0019] The condensate may then flow through a low-pressure
economizer 40 (LPECON), which is a device configured to heat
feedwater with gases, may be used to heat the condensate. From the
low-pressure economizer 40, the condensate may either be directed
into a low-pressure evaporator 42 (LPEVAP) or to an
intermediate-pressure economizer 44 (IPECON). Steam from the
low-pressure evaporator 42 may be returned to the low-pressure
section 26 of the steam turbine 22. Likewise, from the
intermediate-pressure economizer 44, the condensate may either be
directed into an intermediate-pressure evaporator 46 (IPEVAP) or to
a high-pressure economizer 48 (HPECON). In addition, steam from the
intermediate-pressure economizer 44 may be sent to a fuel gas
heater (not shown) where the steam may be used to heat fuel gas for
use in the combustor 18 of the gas turbine 12. Steam from the
intermediate-pressure evaporator 46 may be sent to the
intermediate-pressure section 28 of the steam turbine 22.
[0020] Finally, condensate from the high-pressure economizer 48 may
be directed into a high-pressure evaporator 50 (HPEVAP). Steam
exiting the high-pressure evaporator 50 may be directed into a
primary high-pressure superheater 52 and a finishing high-pressure
superheater 54, where the steam is superheated and eventually sent
to the high-pressure section 30 of the steam turbine 22. Exhaust
from the high-pressure section 30 of the steam turbine 22 may, in
turn, be directed into the intermediate-pressure section 28 of the
steam turbine 22, and exhaust from the intermediate-pressure
section 28 of the steam turbine 22 may be directed into the
low-pressure section 26 of the steam turbine 22.
[0021] An inter-stage attemperator 56 may be located in between the
primary high-pressure superheater 52 and the finishing
high-pressure superheater 54. The inter-stage attemperator 56 may
allow for more robust control of the exhaust temperature of steam
from the finishing high-pressure superheater 54.
[0022] In addition, exhaust from the high-pressure section 30 of
the steam turbine 22 may be directed into a primary re-heater 58
and a secondary re-heater 60 where it may be re-heated before being
directed into the intermediate-pressure section 28 of the steam
turbine 22. The primary re-heater 58 and secondary re-heater 60 may
also be associated with an inter-stage attemperator 62 for
controlling the exhaust steam temperature from the re-heaters.
[0023] In combined cycle systems such as system 10, hot exhaust may
flow from the gas turbine 12 and pass through the HRSG 32 and may
be used to generate high-pressure, high-temperature steam. The
steam produced by the HRSG 32 may then be passed through the steam
turbine 22 for power generation. In addition, the produced steam
may also be supplied to any other processes where superheated steam
may be used. The gas turbine 12 generation cycle is often referred
to as the "topping cycle," whereas the steam turbine 22 generation
cycle is often referred to as the "bottoming cycle." By combining
these two cycles as illustrated in FIG. 1, the combined cycle power
generation system 10 may lead to greater efficiencies in both
cycles. In particular, exhaust heat from the topping cycle may be
captured and used to generate steam for use in the bottoming
cycle.
[0024] Therefore, one aspect of the combined cycle power generation
system 10 is the ability to recapture heat from the heated exhaust
gas 34 using the HRSG 32. As illustrated in FIG. 1, components of
the gas turbine 12 and the HRSG 32 may be separated into discrete
functional units. In other words, the gas turbine 12 may generate
the heated exhaust gas 34 and direct the heated exhaust gas 34
toward the HRSG 32, which may be primarily responsible for
recapturing the heat from the heated exhaust gas 34 by generating
superheated steam. In turn, the superheated steam may be used by
the steam turbine 22 as a source of power. The heated exhaust gas
34 may be transferred to the HRSG 32 through ductwork, which may
vary based on the particular design of the combined cycle power
generation system 10.
[0025] A more detailed illustration of how the gas turbine 12
functions may help illustrate how the heated exhaust gas 34 may be
transferred to the HRSG 32 from the gas turbine 12. Accordingly,
FIG. 2 is a detailed side view of an embodiment of the gas turbine
12 of FIG. 1 having heat exchanger elements of the HRSG 32 of FIG.
1 integrated with components of an exhaust diffuser of the gas
turbine 12. As described with respect to FIG. 1, the gas turbine 12
may include the turbine 16, the combustor 18, and the compressor
20. Air may enter through an air intake 64 and be compressed by the
compressor 20. Next, the compressed air from the compressor 20 may
be directed into the combustor 18 where the compressed air may be
mixed with fuel gas. The fuel gas may be injected into the
combustor 18 through a plurality of fuel nozzles 66. The mixture of
compressed air and fuel gas is generally burned within the
combustion chamber of the combustor 18 to generate a
high-temperature, high-pressure combustion gas, which may be used
to generate torque within the turbine 16. A rotor of the turbine 16
may be coupled to a rotor of the compressor 20, such that rotation
of the turbine rotor may also cause rotation of the compressor 20.
In this manner, the turbine 16 drives the compressor 20 as well as
the load 14 (not shown in FIG. 2). Exhaust gas from the turbine 16
section of the gas turbine 12 may be directed into an exhaust
diffuser 68. In the embodiment of FIG. 2, the exhaust diffuser 68
may be a radial exhaust diffuser, whereby the exhaust gas may be
re-directed by exit guide vanes 70 to exit the exhaust diffuser 68
through a 90-degree turn outwardly (i.e., radially) through an
exhaust plenum (not shown) and a transition inlet to the HRSG
32.
[0026] Another aspect of certain components of the exhaust diffuser
68, in addition to directing the heated exhaust gas 34 to the HRSG
32, may be to ensure that certain aerodynamic properties of the
heated exhaust gas 34 are achieved. For instance, an exhaust frame
strut 72, illustrated in FIG. 2, may be cambered with an airfoil
wrapped around it. The exhaust frame strut 72 may also be rotated
such that swirling of the heated exhaust gas 34 may be minimized
and flow of the heated exhaust gas 34 may generally be more axial
in nature until flowing through the exit guide vanes 70. In
addition, the exit guide vanes 70 may also be designed in such a
way that, when the heated exhaust gas 34 is turned toward the
exhaust plenum at a 90-degree angle, the exit guide vanes 70
minimize the aerodynamic loss incurred in turning the flow 90
degrees radially. Therefore, proper aerodynamic design of the
exhaust frame strut 72, exit guide vanes 70, as well as other
components of the exhaust diffuser 68 within the flow path of the
heated exhaust gas 34, may be a design consideration.
[0027] FIG. 3 is a cut-away perspective view of an embodiment of a
diffuser that may be similar to the diffuser 68 in FIG. 2, but for
convenience, it will be appreciated that the diffuser is not shown
to the same scale as in FIG. 2. The diffuser 68 connects to a
plenum 74 which, along with guide vanes 46, redirects the exhaust
gas substantially ninety (90) degrees and into the transition duct
76 which connects to the HRSG inlet (not shown). The radial guide
vanes 46 may be circular (e.g., tapered annular or conical
structures) and disposed concentrically about the x-axis 31. The
plenum 74 then gradually guides the combustion gases along the
z-axis 35, into the expanding transition section 76 which is
connected to the inlet to the HRSG.
[0028] The plenum 74 in the known configuration shown in FIGS. 3
and 4 is generally square or rectangular in shape, but with a
slanted end wall portion 78 extending from the top wall 80 to a
side wall 82. Walls 80 and 82 are substantially perpendicular to
each other, while upstream and downstream sides 84, 86,
respectively, are parallel as best seen in FIG. 4. The bottom wall
88 is parallel to the top wall 80, but may have a slanted component
90 between the bottom wall 88 and the side wall 82.
[0029] FIGS. 5-7 illustrate a modified plenum 100 in accordance
with an exemplary but nonlimiting embodiment of the invention. The
radial diffuser 101 is received within the plenum inlet, concentric
to the turbine rotor axis 114 (FIG. 7). In this example, the plenum
100 is formed with a radiused end defined by a curved end wall 102
merging with top and bottom walls 104, 106. The curved end wall 102
and top and bottom walls 104, 106 collectively form a peripheral
edge wall upstream and downstream side walls 108, 110,
respectively, which extend from the radiused end wall 102 to the
expanding transition section 112. The curved end wall 102 is drawn
on the center axis 114 of the diffuser 101 (here again, not drawn
to scale), and the top and bottom walls 104, 106 extend
tangentially, in parallel, from opposite ends of the radiused end
wall. Note that the straight top and bottom walls 104, 106 cross
the axis 114 of the diffuser/turbine rotor.
[0030] It will be understood that the internal vane components of
the diffuser may be similar to the arrangement shown in FIG. 3.
[0031] Significantly, the upstream and downstream side walls 108
and 110 are not parallel. As best seen in FIG. 7, the downstream
side wall 110 is perpendicular to the center axis 114, but the
upstream side wall 108 extends at an angle of between 20 and 50
degrees (and preferably between 35 and 45 degrees) relative to the
downstream side wall 110. This expansion of the flow path from the
plenum 100 to the transition section 112 promotes a redistribution
to uniform flow of gases to the HRSG inlet without impact on
diffuser performance. In fact, the uniform flow not only benefits
HRSG performance, but also simplifies the design of the HRSG
silencer located in the HRSG inlet. The plenum design described
herein also enables relatively flat inlet profiles across operating
conditions, and across a range of last stage turbine bucket exit
profiles.
[0032] FIG. 8 illustrates HRSG inlet profiles at the plenum exit
plane 116 and at the downstream edge 118 of the transition section
112. The Y-axis "% Span" refers to the height of the plenum, from
bottom to top. It can be seen that the "total Velocity" of air flow
through the plenum is relatively uniform across the height of the
plenum.
[0033] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *