U.S. patent application number 10/525780 was filed with the patent office on 2005-11-10 for gas turbine.
Invention is credited to Jeppel, Paul-Heinz, Schulten, Wilhelm.
Application Number | 20050247062 10/525780 |
Document ID | / |
Family ID | 31725437 |
Filed Date | 2005-11-10 |
United States Patent
Application |
20050247062 |
Kind Code |
A1 |
Jeppel, Paul-Heinz ; et
al. |
November 10, 2005 |
Gas turbine
Abstract
The invention relates to a gas turbine comprising a combustion
chamber, into which fuel and combustion air are fed and caused to
react, in order to produce a working fluid. The aim of the
invention is to provide a particularly simple construction, which
achieves a relatively high degree of efficiency for the
installation. To achieve this, the inventive combustion chamber can
be cooled and has a tubular structure, the combustion chamber wall
being composed of coolant pipes.
Inventors: |
Jeppel, Paul-Heinz;
(Waltrop, DE) ; Schulten, Wilhelm; (Essen,
DE) |
Correspondence
Address: |
Siemens Corporation
Intellectual Property Department
170 Wood avenue South
Iselin
NJ
08830
US
|
Family ID: |
31725437 |
Appl. No.: |
10/525780 |
Filed: |
February 28, 2005 |
PCT Filed: |
September 1, 2003 |
PCT NO: |
PCT/EP03/09703 |
Current U.S.
Class: |
60/752 ;
60/806 |
Current CPC
Class: |
F23R 2900/00012
20130101; F23R 3/005 20130101 |
Class at
Publication: |
060/752 ;
060/806 |
International
Class: |
F23R 003/42 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2002 |
EP |
02020694.2 |
Claims
1-9. (canceled)
10. A gas turbine, comprising: a combustion chamber having a
combustion chamber wall; and coolant tubes forming the combustion
chamber wall, wherein each coolant tube is comprised of a plurality
of tube segments with consecutive tube segments of a coolant tube
being interconnected via an assigned adapter piece and the adapter
pieces are implemented so that the tube segments can be connected
by a plug and socket connection.
11. The gas turbine according to claim 10, wherein the coolant
tubes are made of cast material.
12. The gas turbine according to claim 10, wherein the coolant
tubes have a trapezoidal cross-section.
13. The gas turbine according to claim 12, wherein the
cross-section of the adapter pieces transition to a circular
cross-section near a relevant joint.
14. The gas turbine according to claim 10, wherein the coolant
tubes are mounted on a plurality of common support rings.
15. The gas turbine according to claim 14, wherein the coolant
tubes are mounted on the support rings via coolable screws.
16. The gas turbine according to claim 14, wherein the support
rings are interconnected by a plurality of longitudinal fins to
form a supporting structure.
17. The gas turbine according to claim 10, wherein each coolant
tube is connected on an output side to a collecting chamber through
which an outflowing coolant is fed to a burner.
18. The gas turbine according to claim 17, wherein each burner is
assigned a collecting chamber and each collecting chamber is
connected to the same number of coolant tubes.
19. A gas turbine combustion chamber, comprising: a combustion
chamber wall; and coolant tubes forming the combustion chamber
wall, wherein each coolant tube is comprised of a plurality of tube
segments with consecutive tube segments of a coolant tube being
interconnected via an assigned adapter piece and the adapter pieces
are implemented so that the tube segments can be connected by a
plug and socket connection.
20. The gas turbine combustion chamber according to claim 19,
wherein the coolant tubes are mounted on a plurality of common
support rings.
21. The gas turbine combustion chamber according to claim 19,
wherein the coolant tubes are mounted on the support rings via
coolable screws.
22. The gas turbine combustion chamber according to claim 19,
wherein the support rings are interconnected by a plurality of
longitudinal fins to form a supporting structure.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is the US National Stage of International
Application No. PCT/EP2003/009703, filed Sep. 1, 2003 and claims
the benefit thereof. The International Application claims the
benefits of European Patent application No. 02020694.2 EP filed
Sep. 13, 2002, both of the applications are incorporated by
reference herein in their entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a gas turbine having a combustion
chamber in which a supplied fuel is brought into reaction with
supplied combustion air to produce a working fluid.
BACKGROUND OF THE INVENTION
[0003] Gas turbines are used in many fields to drive generators or
machines. In such applications the energy content of a fuel is used
to generate a rotational movement of a turbine shaft. For this
purpose the fuel is combusted in a number of burners, with
compressed air being supplied by an air compressor. Combustion of
the fuel produces a high-temperature working fluid which is subject
to high pressure. This working fluid is fed into a turbine unit
connected downstream from the relevant burner, where it expands in
a manner that provides work output. In this arrangement a separate
combustion chamber can be assigned to each burner, the working
fluid flowing out of the combustion chambers being combinable
before or in the turbine unit. Alternatively, however, the gas
turbine can also be designed as what is known as an annular
combustor type, in which most if not all of the burners open out
into a common, typically annular, combustion chamber.
[0004] In the design of gas turbines of this kind a particularly
high level of efficiency is normally one of the design objectives
in addition to the achievable performance. Here, increased
efficiency can basically be achieved for thermodynamic reasons by
increasing the temperature at which the working fluid flows out of
the combustion chamber and into the turbine unit. For this reason
temperatures of around 1200 to 1500.degree. C. are aimed at and
also attained for gas turbines of this kind.
[0005] With the working fluid reaching such high temperatures,
however, the components and parts exposed to this medium are
subject to high thermal stresses. In order nonetheless to ensure a
comparatively long useful life for the affected components, it is
usually necessary to provide a means of cooling the components in
question, in particular the combustion chamber. In order to prevent
thermal deformation of the material which limits the useful life of
the components, efforts are usually made to achieve as uniform a
cooling of the components as possible, cooling air generally being
used as the coolant. In this arrangement the cooling air is usually
fed to the exterior of the inner wall of the combustion chamber via
a cooling system consisting of tubes and partitions.
[0006] However, a cooling system constructed in this manner has the
disadvantage that the design of the combustion chamber and cooling
system is very complex. In particular, the actual combustion
chamber wall is assigned a separate cooling system on its exterior
which in turn has to be mounted from the outside. The process of
producing a combustion chamber of this kind can therefore be very
cost- and labor-intensive, as a large number of individual parts
and joining processes are necessary for manufacture. This
additionally results in increased fault proneness in the
manufacture and operation of the gas turbine. Maintenance and
repairs are likewise rendered more difficult by the complicated
construction of the combustion chamber wall.
SUMMARY OF THE INVENTION
[0007] The object of the invention is therefore to specify a gas
turbine having a particular high efficiency while being of simple
design.
[0008] This object is achieved according to the invention by the
wall of the combustion chamber being formed of coolant tubes.
[0009] The invention is based on the consideration that the gas
turbine must be suitably designed to ensure a particularly high
efficiency for particularly high media temperatures. In order to
minimize fault proneness, particularly reliable cooling of the
thermally stressed components, including the combustion chamber in
particular, must be ensured. This can be achieved with
comparatively little complexity by, on the one hand, making the
combustion chamber wall itself coolable, and, on the other hand,
constructing it from shaped parts that are kept comparatively
simple and flexible. These two aspects of the combustion chamber
embodiment can be adhered to by constructing the surrounding wall
of the combustion chamber or the combustion chamber wall in a
suitable manner from tubes, cooling air being specifically provided
as coolant which, after passing through the coolant tubes, can be
supplied to the combustion chamber as additional combustion air
that has been preheated as a result of combustion chamber
cooling.
[0010] In order to ensure particularly high strength of the
combustion chamber wall, the coolant tubes are advantageously made
of cast material, i.e. in other words each constituting a casting.
A further advantage of this material selection is that reliable
heat insulation can be provided in a particularly simple manner by
suitably coating the cast material with a ceramic protective
layer.
[0011] In order to keep the coolant tubes particularly immune to
thermal stresses and therefore particularly robust, these are
advantageously implemented with a trapezoidal cross-section. This
cross-sectional shape exhibits a particularly high thermal
elasticity resulting in only slight thermal stresses between cold
and warmer areas of the tube even in the event of markedly
differential heating of individual circumferential segments of the
relevant tube, thereby achieving a long service life of the coolant
tubes.
[0012] To form the combustion chamber wall and therefore also the
actual combustion chamber, the coolant tubes are expediently
mounted on support rings oriented in the circumferential direction
of the combustion chamber. Through their position and form, these
support rings dictate the shape of the combustion chamber annulus
to be implemented by the coolant tubes, thereby enabling a
mechanically stable combustion chamber structure to be produced in
the manner of a self-supporting structure using only a small number
of further components in addition to the actual tubes.
[0013] The coolant tubes are expediently mounted on the support
rings via cooled screws, the mounting of the coolant tubes via
screws allowing individual or even a plurality of coolant tubes to
be installed or dismantled in a particularly time-saving manner
from the hot gas side while maintaining high strength, i.e. without
having to disassemble the combustion chamber.
[0014] To ensure particularly high combustion chamber strength, the
support rings are advantageously interconnected by a number of
longitudinal fins in addition to the actual coolant tubes. The
longitudinal fins and the support rings mounted perpendicular to
them together form a supporting structure having a high degree of
rigidity and strength. To provide a supporting structure of
particularly high stability, the support rings and longitudinal
fins are preferably welded together so that the rings and fins form
a welded support frame.
[0015] A particularly high degree of flexibility in the shaping of
the combustion chamber, allowing in particular flow conditions in
the working fluid to be taken into account even in the combustion
chamber while at the same time enabling a sufficient length and
shape of the coolant tubes to be ensured, can be achieved in that
the coolant tubes expediently consist of two or more tube segments
interconnected in their longitudinal direction. The advantage of
tube segmentation can be specifically that manufacturing
difficulties in producing cast iron coolant tubes of sufficient
length and appropriate shape are avoided.
[0016] In order to interconnect two consecutive segments of a
coolant tube, each segment preferably has an assigned adapter piece
or fitting on its relevant end, the adapter pieces being
expediently designed for easy interconnectability particularly in
respect of their shaping. In a further advantageous embodiment, the
adapter pieces are specifically selected such that segments can be
interconnected by means of a plug and socket connection. If the
coolant tube cross-section is trapezoidal, the cross-section of the
adapter piece is expediently selected such that it changes to a
circular cross-section as it approaches the joint or the relevant
tube segment end. A circular end cross-section of this kind allows
particularly easy machiriability for precision-fit connection to
the next tube segment.
[0017] In order to ensure effective cooling of the coolant tubes
forming the combustion chamber wall, these are advantageously
impingement-cooled in an inlet area for the coolant. For this
purpose, holes through which the coolant can flow are drilled in
the outside of the coolant tubes. The coolant can therefore impinge
on the inside of the tube and ensure a particularly intensive
cooling effect in this area through intimate contact with the tube
material. In the adjacent region, the coolant flows through the
tubes in the longitudinal direction, cooling them by contact.
[0018] This cooling system has the advantage, on the one hand, that
it is incorporated in the design of the combustion chamber wall and
therefore only a small number of additional parts are required for
constructing the cooling system. On the other hand, only a small
coolant pressure loss occurs precisely due to the comparatively
straight-line outflow of the coolant. The advantage of this is that
it facilitates a high degree of turbine efficiency even on the
coolant side.
[0019] To ensure a particularly high overall efficiency of the gas
turbine, the heat input to the coolant is advantageously recovered
for the actual energy conversion process in the gas turbine. For
this purpose the cooling air used as coolant and which has been
heated during the cooling process is advantageously injected into
the combustion chamber, the pre-heated cooling air being able to be
used as the only combustion air or as additional combustion
air.
[0020] In order to feed the outflowing coolant to the combustion
process in the combustion chamber for this purpose, each coolant
tube is preferably connected on the output side to a collecting
chamber which for its part is disposed upstream of the combustion
chamber on the air side. Via this chamber, the coolant can be mixed
with the remaining compressor mass flow by a throttling device and
fed to the combustion process.
[0021] Compensation of the flow conditions is achievable to an
particular degree by assigning a collecting chamber of this kind to
each burner, the design basis being such that the same quantity of
cooling air or coolant is fed to each collecting chamber. To this
end each burner is preferably assigned a collecting chamber, each
connecting chamber being connected to the same number of coolant
tubes. The particular advantage of this arrangement is that each
burner is fed approximately the same amount of returned cooling
air. Just by implementing the combustion chamber as an annular
combustor ensures that a particularly homogenous combustion process
is thereby produced in the combustion chamber.
[0022] The advantages achieved with the invention are specifically
that particularly reliable combustion chamber cooling of simple
design is made possible by implementing the combustion chamber wall
as a plurality of interconnected coolant tubes provided for the
through-flow of coolant, specifically cooling air. The integration
of the coolant tubes in a self-supporting combustion chamber
structure, in particular by means of the support rings, allows
comparatively easy interchangeability of even individual
maintenance-requiring tubes, a simple means of replacing combustion
chamber structures in existing gas turbines also being provided,
however, because of the flexibility achievable via the tubular
design. Moreover, the tubular combustion chamber structure is
comparatively stable and immune to vibrations of the combustion
chamber wall, as the coolant tubes lend rigidity and strength to
the annulus. The basic flexibility in terms of shaping and
component selection achieved by constructing the combustion chamber
wall from tube elements additionally enables probes or monitoring
sensors for monitoring and/or diagnostics of the actual combustion
process in the combustion chamber to be mounted, particularly by
selectively using specifically modified tubes which allow, for
example, suitable probes to be fed through from the outside to the
inside of the combustion chamber.
BRIEF DESCDRIPTION OF THE DRAWINGS
[0023] An exemplary embodiment of the invention is now explained in
greater detail with reference to the accompanying drawings in
which:
[0024] FIG. 1 shows a half-section through a gas turbine,
[0025] FIG. 2 shows in longitudinal section a segment of the
combustion chamber of the gas turbine according to FIG. 1, and
[0026] FIG. 3a to c each show in cross-section a detail of the
combustion chamber wall according to FIG. 2.
[0027] The same parts are denoted by the same reference characters
in all the Figures.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The gas turbine 1 according to FIG. 1 has a compressor 2 for
combustion air, a combustion chamber 4 as well as a turbine 6 for
driving the compressor and a generator (not shown) or a machine.
For this purpose the turbine 6 and the compressor 2 are disposed on
a common turbine shaft 8, also referred to as a turbine rotor, to
which the generator or the driven machine are connected and which
is pivotally mounted about its central axis 9.
[0029] The combustion chamber 4 implemented in the form of an
annular combustor is equipped with a number of burners 10 for
combusting a liquid or gaseous fuel. It is additionally provided
with heat shield elements (not shown in greater detail) on its
inner wall.
[0030] The turbine 6 has a number of rotating blades 12 connected
to the turbine shaft 8. These rotor blades 12 are disposed in a
ring shaped manner on the turbine shaft 8, thereby forming a number
of rotor blade rows. The turbine 6 additionally comprises a number
of fixed guide vanes 14 which are likewise mounted in a ring shaped
manner on an inner casing 16 of the turbine 6, forming guide vane
rows. The rotor blades 12 are used to drive the turbine shaft 8 by
pulse transmission from the working fluid M flowing through the
turbine 6, whereas the guide vanes 14 serve to direct the flow of
the working fluid M between two consecutive rotor blades rows or
rotor blade rings viewed in the direction of flow of the working
fluid M, a consecutive pair from a ring of guide vanes 14 or guide
vane row and from a ring of rotor blades 12 or rotor blade row also
being referred to as a turbine stage.
[0031] Each guide vane 14 has a platform 18, also referred to as a
blade root, which is disposed as a wall element for fixing the
relevant guide vane 14 on the inner casing 16 of the turbine 6,
said platform 18 being a comparatively heavily thermally stressed
component forming the external boundary of a hot gas channel for
the working fluid M flowing through the turbine 6. Each rotor blade
12 is similarly mounted on the turbine shaft 8 via a platform 20
also referred to as a blade root.
[0032] A guide ring 21 is disposed on the inner casing 16 of the
turbine 6 between the spaced-apart platforms 18 of the rotor blades
14 of two adjacent rotor blade rows in each case, the outer surface
of each guide ring 21 likewise being exposed to the hot working
fluid M flowing through the turbine 6 and being separated from the
outer end 22 of the opposite rotor blade 12 by a gap in the radial
direction, the guide rings 21 disposed between adjacent rows of
guide vanes being used in particular as cover elements which
protect the inner wall 16 or other integral parts of the casing
from thermal overstressing by the hot working fluid M flowing
through the turbine 6.
[0033] To achieve a comparatively high level of efficiency, the gas
turbine 1 is designed for a comparatively high exit temperature of
the working fluid M leaving the combustion chamber 4 of around 1200
to 1500.degree. C. In order also to ensure a long lifetime or
operating life of the gas turbine 1, its main components such as
the combustion chamber 4 in particular are implemented in a
coolable manner whereby, in order to ensure a reliable and
sufficient supply of cooling air to the combustion chamber wall 23
of the combustion chamber 4 as coolant K, the combustion chamber
wall 23 is of tubular construction comprising a plurality of
coolant tubes 24 interconnected in a gas-tight manner to form said
combustion chamber wall 23.
[0034] In the exemplary embodiment the combustion chamber 4 is
designed as a so-called annular combustor, wherein a plurality of
burners 10 arranged in the circumferential direction around the
turbine shaft 8 open out into a common combustion chamber space.
For this purpose the combustion chamber 4 is implemented in its
totality as an annular structure which is positioned around the
turbine shaft 8. To further clarify the embodiment of the
combustion chamber wall 23, FIG. 2 shows in longitudinal section a
segment of the combustion chamber 4 which continues in a toroidal
manner around the turbine shaft 8 to form the combustion chamber
4.
[0035] As shown in the diagram according to FIG. 2, the combustion
chamber 4 has an initial or inflow section into which the outlet of
the respective assigned burner 10 opens at the end. Viewed in the
direction of flow of the working fluid M, the cross-section of the
combustion chamber 4 then narrows, with account being taken of the
resulting flow profile of the working fluid M in this area. On the
outlet side, the combustion chamber 4 exhibits in its longitudinal
cross-section a curvature which favors the outward flow of the
working fluid M from the combustion chamber 4 resulting in a
particularly high pulse and energy transmission to the following
first row of rotor blades seen from the flow side.
[0036] As shown in the diagram according to FIG. 2, the combustion
chamber wall 23 is formed, both in the external area of the
combustion chamber 4 and in its inner area, from coolant tubes 24
which are oriented with their longitudinal axis essentially
parallel to the flow direction of the working fluid M inside the
combustion chamber 4, the coolant tubes 24 being made of cast
material which has been suitably selected specifically with regard
to a particularly high mechanical and thermal strength of said
coolant tubes.
[0037] In order to provide particularly high flexibility in the
shaping of the combustion chamber 4 formed from the coolant tubes
24 to suit the required flow conditions of the working fluid M, in
the exemplary embodiment each coolant tube 24 is constituted by a
suitable combination of a plurality of consecutive tube segments
26, the type and number of said tube segments 26 being selected in
such a way that, on the one hand, a particularly high mechanical
strength of each individual tube segment 26 is ensured with regard
to the length and shaping of each tube segment 26 and with regard
to the cast material used, the shaping on the other hand being
suitably selected in each case taking into account the required
flow path for the working fluid M. The comparatively sharp local
curvature possibly required can be provided in a particularly
simple and reliable manner by the segmentation of the coolant tubes
24.
[0038] The coolant tubes 24 are additionally designed to be
particularly strong specifically with regard to locally varying
thermal loading and the resulting thermal stresses. For this
purpose, the coolant tubes 24 and in particular the tube segments
26 forming them are of essentially trapezoidal cross-section, as
shown for the central piece of a tube segment 26 in FIG. 3a, the
coolant tubes 24 having a comparatively longer inner side 28 and a
comparatively shorter outer side 30 in cross-section to form the
toroidal, intrinsically curved structure of the combustion chamber
4. To seal the interspaces between adjacent coolant tubes 24, a
suitable seal, e.g. a brush seal 32, is provided so as to produce a
gas-tight and enclosed combustion chamber 4 by means of a suitable
combination of coolant tubes 24.
[0039] The trapezoidal embodiment of the tube cross-sections favors
in particular an intrinsically planar embodiment of the structure
obtainable by joining together adjacent coolant tubes 24, so that
the enclosed implementation of the combustion chamber 4 can be
achieved in a comparatively simple manner.
[0040] For the segmented construction of the coolant tubes 24, the
connection of two consecutive tube segments 26 of each coolant tube
24 on the coolant side has been kept particularly simple,
particularly with regard to assembly and maintenance purposes. To
achieve this, consecutive tube segments 26 of a coolant tube 24 are
interconnected via an assigned adapter piece 34. To facilitate
assembly of consecutive tube segments 26, each tube segment 26 is
of essentially circular cross-section in its end areas to form the
relevant adapter piece 34, as shown in FIG. 3b. By producing the
coolant tubes 24 from cast material, the shaping of the relevant
adapter piece 34 to suit the relevant tube segment 26 is possible
in a comparatively simple manner, there being provided in the
adapter area a continuous transition from the actually trapezoidal
cross-section of the relevant tube segment 26 to the circular
cross-section provided at the end. As shown in FIG. 2, the relevant
adapter pieces 34 are displaced into the outer area of the
combustion chamber 4 with respect to their central line and in
comparison to the central pieces of the relevant tube segments 26,
so that an essentially continuous smooth surface can be provided
using suitable seal strips or plates in the inner walls of the
combustion chamber 4.
[0041] To form the combustion chamber 4 as an integral,
self-supporting structure, the coolant tubes 24 are mounted on a
plurality of common support rings 36 which enclose the combustion
chamber 4 formed from the actual coolant tubes 24 at a suitably
selected spacing viewed in the longitudinal direction or in the
flow direction of the working fluid M. The relevant coolant tubes
24 or the tube segments 26 forming them are mounted on the support
rings 36 via coolable screws 38, as shown in the embodiment
according to FIG. 3c. For further stiffening and mechanical fixing
of the self-supporting structure forming the combustion chamber 4,
the support rings 36 are interconnected by longitudinal fins
essentially oriented in the longitudinal direction or in the flow
direction of the working fluid M.
[0042] The tubular design of the combustion chamber 4 means that a
comparatively large amount of cooling air can be applied to the
combustion chamber wall 23 as coolant K with only comparatively low
pressure losses. In order enable the heating of the coolant K
flowing through the coolant tubes 24 for cooling the combustion
chamber wall 23 to be used for the actual combustion process in a
manner promoting thermodynamic efficiency, provision is made for
the coolant K issuing from the coolant tubes 24 to be injected into
the combustion chamber 4 as the sole or additional combustion air.
For this purpose provision is made for supplying the coolant K to
the coolant tubes 24 at their ends assigned to the outlet of the
combustion chamber 4, where the coolant K is supplied to the
coolant tubes 24 via suitable inflow ports 42, as shown in FIG. 2,
said inflow ports 42 being positioned in respect of their spatial
orientation in such a way that impingement cooling of the relevant
tube segment 26 initially takes place in the outlet area of the
combustion chamber 4 by means of the cooling air flowing in as
coolant K. Deflection of the coolant K then takes place inside the
relevant tube segment 26, and the coolant K then flows through the
relevant coolant tube 24 in its longitudinal direction, cooling
taking place through contact of the coolant K with the relevant
tube walls.
[0043] In the manner of a counter-flow to the actual working medium
M, the coolant K therefore flows inside the coolant tubes 24 from
the outlet area of the combustion chamber 4 to its inflow area in
which the relevant burner 10 is also disposed. In this area the
coolant K now heated or pre-heated by the continuous cooling of the
relevant coolant tube 24 flows out of the coolant tubes 24 and is
then assigned to a subordinate collecting chamber 46. The coolant
tubes 24 are connected via said collecting chamber 46 to the
assigned burner 10 on the output side so that the coolant K flowing
out of the coolant tubes 24 can be used as combustion air in the
relevant burner 10. Depending on the design of the gas turbine 1,
the feeding of the relevant burner 10 with combustion air can be
provided exclusively via the coolant K flowing out of the coolant
tubes 24 or also using in some cases additionally required further
combustion air supplied from an external source.
[0044] By the very embodiment of the combustion chamber 4 as an
annular combustor, a maximally symmetrical arrangement of the
burners 10 and consequently a maximally symmetrical adjustment of
the flow conditions within the combustion chamber 4 is ordinarily
advantageous. For the gas turbine 1, this basic principle is also
taken into account on the coolant side, specifically in that the
same number of coolant tubes 24 is assigned to each burner 10 on
the combustion air side.
* * * * *