U.S. patent application number 13/859002 was filed with the patent office on 2013-08-29 for method and burner arrangement for the production of hot gas, and use of said method.
This patent application is currently assigned to ALSTOM Technology Ltd. The applicant listed for this patent is Alstom Technology Ltd. Invention is credited to Richard CARRONI, Bettina PAIKERT.
Application Number | 20130224672 13/859002 |
Document ID | / |
Family ID | 39524181 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130224672 |
Kind Code |
A1 |
CARRONI; Richard ; et
al. |
August 29, 2013 |
METHOD AND BURNER ARRANGEMENT FOR THE PRODUCTION OF HOT GAS, AND
USE OF SAID METHOD
Abstract
A method for producing hot gas for operating a turbomachine
fired with at least one combustion chamber includes premixing a
fuel with a plurality of operating gases by introducing fuel into
the plurality of operating gases in a mixing chamber disposed
upstream of the combustion chamber using a burner arrangement,
wherein the fuel includes at least one of a combustible gas and a
H.sub.2-rich fuel; and introducing the premixed fuel into the
combustion chamber.
Inventors: |
CARRONI; Richard;
(Niederrohrdorf, CH) ; PAIKERT; Bettina;
(Oberrohrdorf, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Alstom Technology Ltd; |
|
|
US |
|
|
Assignee: |
ALSTOM Technology Ltd
Baden
CH
|
Family ID: |
39524181 |
Appl. No.: |
13/859002 |
Filed: |
April 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12876508 |
Sep 7, 2010 |
8459985 |
|
|
13859002 |
|
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|
PCT/EP2009/051764 |
Feb 16, 2009 |
|
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12876508 |
|
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Current U.S.
Class: |
431/354 |
Current CPC
Class: |
F23C 2900/07002
20130101; F23R 2900/00014 20130101; F23C 2900/9901 20130101; F23D
14/62 20130101; F23D 14/02 20130101; F23R 3/286 20130101; F23C
7/002 20130101 |
Class at
Publication: |
431/354 |
International
Class: |
F23D 14/02 20060101
F23D014/02; F23D 14/62 20060101 F23D014/62 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2008 |
CH |
00350/08 |
Claims
1. A burner arrangement disposed upstream of a combustion chamber
comprising: a mixing chamber configured to premix a fuel with a
plurality of operating gases; and a swirler having at least two
hollow partial conical shells nested one inside the other in a flow
direction and complementing one another to form a body with an
interior space, wherein a cross section of the interior space
increases in the flow direction, wherein the at least two conical
shells each have a wall and each have a longitudinal axis of
symmetry, wherein the longitudinal axes of symmetry of the hollow
shells run offset with respect to one another such that the walls
of each shell are adjacent to each other and form a tangential air
inlet slot extending longitudinally for an inflow of the air into
the interior space.
2. The burner arrangement as recited in claim 1, further comprising
a mixing tube and a transition region disposed between the swirler
and the mixing tube, the transition region containing transition
passages for a transfer of a flow formed in the swirler and into a
throughflow cross section of the mixer tube connected downstream of
the transfer passages.
3. The burner arrangement as recited in claim 2, wherein a number
of the transfer passages corresponds to a number of the at least
two shells.
4. A burner arrangement disposed upstream of a combustion chamber
comprising: a mixing chamber configured to premix a fuel with a
plurality of operating gases; and a swirler having at least two
hollow partial shells nested one inside the other in a direction of
flow and complementing one another to form a body with an interior
space, wherein a cross section of the interior space is
substantially cylindrical in a flow direction, and wherein the at
least two hollow shells each have a wall and each have a
longitudinal axis of symmetry, wherein the longitudinal axes of
symmetry of the hollow shells run offset with respect to one
another such that the walls of each shell are adjacent to each
other and form a tangential air inlet slot extending longitudinally
for an inflow of the air into the interior space, wherein the
interior space includes an internal body having a decreasing cross
section in the flow direction.
5. The burner arrangement as recited in claim 4, wherein a size of
the inner body decreases conically in the direction of flow.
6. The burner arrangement as recited in claim 4, further comprising
a mixing tube and a transition region disposed between the swirler
and the mixing tube, the transition region containing transition
passages for a transfer of a flow formed in the swirler and into a
throughflow cross section of the mixer tube connected downstream of
the transfer passages.
7. The burner arrangement as recited in claim 6, wherein a number
of the transfer passages corresponds to a number of the at least
two shells.
Description
CROSS REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/876,508, filed Sep. 7, 2010, which is a continuation of
International Patent Application No. PCT/EP2009/051764, filed Feb.
16, 2009, which claims priority to Swiss Patent Application No. CH
00350/08, filed Mar. 7, 2008. The entire disclosure of both
applications is incorporated by reference herein.
FIELD
[0002] The present invention relates to the field of combustion
technology. It refers to a method for combusting H.sub.2-rich
fuels. It also refers to a burner arrangement for implementing the
method and for its use.
BACKGROUND
[0003] From WO-A1-2006/069861, a premix burner with subsequent
mixing section or mixer tube (a so-called AEV burner) has been
known, in which in the premix burner, which is formed according to
EP-A1-704 657, a first fuel can be centrally injected and between
the air inlet slots or passages which are formed by the shells in
the swirler (shown clearly especially in EP-A1 321 809) at least
one second fuel can be introduced into the air which flows into the
inner space there. In the subsequent mixer tube, provision is made
for a further device for injecting a third fuel. All printed
publications which are referred to here or later, and their further
developments, form an integrating element of this application.
[0004] For combusting H.sub.2-rich fuels, as created for example in
the form of syngas during coal gasification, it has already been
proposed to inject at least some of the H.sub.2-rich fuel via the
mixer tube of such a premix burner. Also, such a premix burner has
already been tested with natural gas in lean premix operation,
during which under high pressure H.sub.2-rich fuels with
H.sub.2-to-N.sub.2 ratios of 70/30 and 60/40 have been injected in
an axially staged manner in the premix burner and in the mixer
tube.
[0005] During these tests, it has been shown that if a changeover
is made from natural gas entirely to the H.sub.2-rich fuel, the
flame migrates upstream into the mixer tube. Although the burner
was able to be operated in this way without damage and with
sufficiently low NOx emission, numerous disadvantages arose,
however, specifically: [0006] The pressure losses in the premix
burner are increased by the factor of 3. This is undesirable in the
case of gas turbines with regard to an associated gas turbine
cycle. [0007] The available mixing length, i.e. the distance
between the location of the injection of the fuel and the flame
front, is reduced, which leads to increased NOx-emission. [0008]
High-frequency pulsations gain in importance. In this context, it
may be mentioned that the thermoacoustic vibrations represent a
hazard for each type of combustion application. They lead to
high-amplitude pressure vibrations, to limitation of the operating
range, and they can increase pollutant emissions. This applies
especially to combustion systems with low acoustic damping, as is
the case for example in annular combustion chambers with
reverberant walls. In order to ensure a high performance conversion
over a wide operating range with regard to pulsations and pollutant
emissions, provisions against these pulsations must be made.
SUMMARY OF THE INVENTION
[0009] In an aspect of the invention, a method for combusting
H.sub.2-rich fuels is provided which reliably prevents migrating of
the flame back into the burner and also pulsations, even during a
changeover from natural gas to H.sub.2-rich fuels.
[0010] In an embodiment of the invention, in addition to the
H.sub.2-rich fuel, a small amount of natural gas is introduced into
the burner arrangement during premix operation and combusted
together with the H.sub.2-rich fuel.
[0011] One development of the method according to the invention is
characterized in that first of all an air/fuel mixture is created
from the air and the natural gas, and in that the H.sub.2-rich fuel
is then injected into the air/fuel mixture. In particular, a burner
arrangement, which comprises a premix burner and a mixer tube which
is connected to it, is used for this purpose, wherein the fuel/air
mixture is created in the premix burner. The H.sub.2-rich fuel can
be injected into the mixer tube and/or into the swirler. A swirler
can be advantageously used as the head stage of the premix burner,
as is described for example in EP-A1-321 809.
[0012] Another development of the method according to the invention
is characterized in that first of all the natural gas and the
H.sub.2-rich fuel are intermixed, and in that the resulting fuel
mixture is mixed and combusted with air in the burner arrangement.
As a result of this, the system of fuel feed and fuel distribution
can especially be simplified. Also in this case, a burner
arrangement can preferably be used which comprises a premix burner
and a mixer tube which is connected to it, wherein in the premix
burner the air/fuel mixture is created from the air and the fuel
mixture.
[0013] A burner arrangement can also be used, however, as is
disclosed for example in WO-A1-2007/113074, in which within the
scope of a sequential combustion a fuel lance projects into a hot
gas flow, and wherein the fuel mixture is injected via the fuel
lance, if necessary with additional air, into the hot gas flow. The
fuel lances which are shown in this printed publication (FIGS. 2-6)
are designed for use in the low-pressure combustion chamber (Pos.
14). Also, this last-named printed publication forms an integrating
element of this application. The operation of such a low-pressure
combustion chamber with the use of a fuel lance which is described
above in a sequentially fired gas turbine, results for example from
EP 620 362 A1, which printed publication also represents an
integrating element of this description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention shall subsequently be explained in more detail
based on exemplary embodiments in conjunction with the drawing. All
elements which are not necessary for the direct understanding of
the invention have been omitted. Like elements are provided with
the same designations in the various figures. The flow direction of
the media is indicated by arrows.
[0015] In the drawings:
[0016] FIG. 1 shows a simplified schematized view of a burner
arrangement of the AEV type, in which according to one exemplary
embodiment of the method according to the invention the additional
natural gas and the H.sub.2-rich fuel are injected one after the
other in the flow direction, wherein the H.sub.2-rich fuel can also
be selectively injected into the swirler;
[0017] FIG. 2 shows a view which is comparable to FIG. 1 of a
burner arrangement of the AEV type, in which according to another
exemplary embodiment of the method according to the invention the
additional natural gas and the H.sub.2-rich fuel are first of all
mixed and the resulting mixture is then injected;
[0018] FIG. 3 shows a simplified schematized view of a burner
arrangement with a fuel lance, which is provided for sequential
combustion, in which according to another exemplary embodiment of
the method according to the invention the additional natural gas
and the H.sub.2-rich fuel are first of all mixed and the resulting
mixture is then injected into a hot gas flow; and
[0019] FIG. 4 shows use of the fuel lance according to FIG. 3 in a
combustion chamber of a gas turbine with sequential combustion.
DETAILED DESCRIPTION
[0020] Reproduced in FIG. 1, in a simplified schematized view, is a
burner arrangement with a head stage, which is formed as a swirler,
and an adjoining mixer tube, in which according to one exemplary
embodiment of the method according to the invention the additional
natural gas and the H.sub.2-rich fuel are injected one after the
other in the flow direction. The burner arrangement 10 comprises a
swirler 11, which at times can also be used as a stand-alone premix
burner, wherein this is formed in a known manner per se in the
shape of a cone, as is described for example in EP-A1-321 809. In
this case, it is important that the swirl intensity in the swirler
is selected via its geometry so that the bursting of the vortex, or
vortices, does not take place in the mixer tube but further
downstream at the combustion chamber inlet, wherein the length of
the mixer tube 13 is to be dimensioned so that a satisfactory
mixture quality is established for all fuels which are in use. If
such a swirler is taken as a basis, then the swirl intensity
results from the design of the corresponding cone angle, of the air
inlet slots or passages, and their number. Combustion air flows
into the interior of the premix burner 11 through said air inlet
slots or passages, wherein in the region of these air inlet slots
or passages provision is made for means for injecting a fuel in
such a way that an air/fuel mixture 12 is formed in the inner space
which is formed by the partial cone shells. The air/fuel mixture 12
is given a swirl around the axis 15 of the burner arrangement 10
and enters a mixer tube 13 downstream, where the complete
mixing-through of air and fuel takes place. The mixer tube 13 opens
into a combustion chamber 14 in which a flame front is formed, with
which the air/fuel mixture is combusted. On the mixer tube 13,
provision is made for an injection device 16 of preferably annular
design, through which fuel can be additionally injected into the
mixer tube 13 and incorporated into the combustion. When required,
transfer passages, which are not shown in more detail in this
figure, are provided in a transition region between swirler 11 and
mixer tube 13 and undertake the transfer of air or air/fuel flow,
which is formed in the swirler 11, into the mixer tube 13. Such a
configuration results from EP-A1-704 657, wherein its disclosure
content forms an integrating element of this application.
Furthermore, the swirler can be designed so that this comprises at
least two hollow partial shells which are nested one inside the
other in the flow direction, making up a body, the cross section of
which in the flow direction, in contrast to the swirler 11 above,
does not extend conically but cylindrically or virtually
cylindrically, wherein in the inner space, preferably on the
symmetry axis of the body, an inner body is provided, the cross
section of which in the flow direction reduces conically or
virtually conically. Such a configuration has been known for
example from EP-A1-777 081, wherein this printed publication also
forms an integrating element of this application.
[0021] According to the exemplary embodiment which is shown in FIG.
1, a small quantity of natural gas F1 is injected into the premix
burner 11 during premix operation and mixed with air. The natural
gas F1 is fed via a first fuel feed line 17 and can be adjusted to
the required mass flow for example by means of a valve 19. The main
part of the output of the burner arrangement 10 is contested,
however, by an H.sub.2-rich fuel F2 which is directed to the
injection device 16 via a second fuel feed line 18 and injected
there into the air/fuel mixture 12 from the swirler 11 acting
upstream. A portion of this H.sub.2-rich fuel 18' can also be
selectively injected into the swirler 11, as results from FIG. 1,
wherein its portion typically constitutes up to 30%. This type of
burner operation has the following advantages: [0022] The pressure
loss coefficient Zeta is reduced from 2.8 to 1.5, which corresponds
to a sharp reduction of the pressure loss in the burner. [0023] The
high-frequency pulsations (of 2 to 4 kHz) are practically
eliminated. [0024] NOx-emissions are minimized, this based on the
fact that the flame is maintained by a maximized premixed air/fuel
mixture. [0025] The fuel feed lines 17 in the region of the swirler
11 are constantly purged for the natural gas so that changing over
to natural gas operation is possible within an extremely short
time. [0026] If the flame front actually migrates upstream into the
burner, it is anchored relatively far downstream in the mixer tube
and burns in a stable and reliable manner. If in a multi-burner
arrangement, as is customary in gas turbines, a flashback occurs in
a burner, this leads more easily to a stable state in the burner
and not to an operation-relevant negative development in which the
flame front migrates still further upstream until destruction of
the burner commences, as is immanently the case in normal burners.
If this state occurs, then the reason to be looked for is that the
burner in question is blocked and the throughflow of air is
reduced. This then also means that an individual burner can be
temporarily shut down and reignited. The operation of the other
burners in the gas turbine is consequently not affected. [0027] The
reason that the flame front in this case cannot flash back to the
premixed burner 11 which is used according to the invention, and
destruction cannot correspondingly occur, is to be seen as that of
the very same flame front assuming a fixed local anchoring inside
the mixer tube 13 in such a way that it also cannot creep upstream
either, the air flow hardly being impaired in the process.
[0028] Whereas in the exemplary embodiment of FIG. 1 the natural
gas F1 and the H.sub.2-rich fuel F2 are injected separately and in
axial staging in the burner arrangement 10, it is also conceivable
to premix the two fuels before injection according to FIG. 2. For
this purpose, the two fuel feed lines 17 and 18 for the fuels F1
and F2 are brought together and the resulting fuel mixture is then
injected on the one hand into the swirler 11 and on the other hand
into the injection device 16 on the mixer tube 13.
[0029] Stabilizing the flame position and limiting NOx-emissions
which is associated therewith, and avoiding pulsations by means of
a small addition of natural gas, can also be applied in a gas
turbine with sequential combustion, specifically in the second or
subsequent combustion stage. In FIG. 3, a fuel lance 20 is
reproduced, as is disclosed in WO-A1-2007/113074 which is referred
to in the introduction, wherein this printed publication also forms
an integrating element of this application. The fuel lance 20
projects into the hot gas flow 26 from a previous combustion stage
which can comprise for example the burner arrangement which is
shown in FIG. 1. In the fuel lance 20, an outer tube 21 and an
inner tube 22 are arranged one inside the other. The outer tube has
injection orifices 23. Air 25 is fed into the gap between inner
tube 22 and outer tube 21, while through the inner tube 22 a
mixture consisting of the H.sub.2-rich fuel F2 and the small
portion of natural gas F1 is introduced. The air/fuel mixture which
is formed discharges into the hot gas flow 26 and ignites there,
forming a flame.
[0030] FIG. 4 shows in schematic view a low-pressure combustion
chamber 27 in a gas turbine which is operated by means of
sequential combustion. Such a gas turbine results for example from
an article by Joos, F. et al., "Field Experience of the Sequential
Combustion System for the ABB GT24/GT26 Gas Turbine Family",
IGTI/ASME 98-GT-220, 1998 Stockholm, wherein FIG. 1 shows the
construction of such a gas turbine. Furthermore, reference is made
to a publication in ABB Review February 1997 (pages 4-14),
especially to FIG. 15 (page 13), in which the main components of
such a gas turbine are also shown. The low-pressure combustion
chamber is referred to here as a "SEV combustor". The operation of
this low-pressure combustion chamber 27 is designed for
self-ignition, i.e. the hot gas flow 26 which flows into the
combustion chamber 27 has a very high operating temperature in such
a way that combustion of the fuels F1 or F1+F2 or F2, which are
injected via at least one fuel lance 20, is carried out by means of
self-ignition. With this type of combustion, it is important that
the flame front in the combustion chamber 14 which is arranged
downstream remains stable as regards location. Also, for achieving
this aim, provision is made in this self-ignition combustion
chamber 27, preferably arranged on the inner or outer wall in the
circumferential direction, for a row of elements 28, so-called
vortex generators, which are positioned in the axial direction
preferably upstream of the fuel lance 20 which basically comprises
a vertical outer tube 21 and a horizontal outer tube 21'. The
purpose of these elements 28 is to generate vortices which induce a
backflow zone. The design of these vortex generators 28 and also
the arrangement in the combustion chamber 27 results from DE-44 46
611 A1, wherein this printed publication also forms an integrating
element of this description. With regard to the different injection
possibilities 29 of the fuels F1 or F1+F2 of F2 into the combustion
chamber 27, reference is made essentially to WO 2007/113074 A1. A
further possibility is apparent in FIG. 4 itself, in which the
symbolized fuel jets 29 flow from one or more injection orifices
which are arranged on the circumference of the axial outer tube 21'
of the fuel lance 20 and inject the fuel, or fuels, into the
flowing 26 of the combustion chamber 27 at a specific injection
angle .alpha.. This injection angle a preferably varies between
20.degree. and 120.degree. in relation to the surface of the
horizontal outer tube section 21' of the fuel lance 20, wherein
injection angles of less than 20.degree. and more than 120.degree.
are also possible, however. A further injection of the fuels F1 or
F1+F2 or F2 is provided downstream of the fuel lance 20 via the
injection device 16 which also has one or more injection orifices,
wherein the direction of the fuel jets 30 can assume a broad
spectrum, as results from FIG. 4, the injection preferably having
an angle .alpha.' of between 20.degree. and 120.degree. in relation
to the surface of the inner wall of the combustion chamber 27,
wherein injection angles of less than 20.degree. and more than
120.degree. are also possible. The type of operation of this
combustion chamber 27 concerning the fuels which are introduced
there and with regard to the injection angle of the fuel jets or of
the fuel orifices 29, 30, depends upon factors which are related to
the sequential combustion. Naturally, the introduction of the fuels
according to FIG. 4 can also be provided in the same or similar
manner in the case of the previously described combustion chambers
according to FIGS. 1 and 2. An additional introduction of a
quantity of air, as results from FIG. 3, is likewise possible and
also provided, when required, also during operation of the
combustion chamber 27 from FIG. 4.
[0031] The subject according to the invention can be used with
particular advantage in a gas turbine with at least one combustion
chamber stage, wherein the hot gas which is produced is expanded in
the gas turbine, performing work.
LIST OF DESIGNATIONS
[0032] 10 Burner arrangement [0033] 11 Swirler [0034] 12 Air/fuel
mixture [0035] 13 Mixer tube [0036] 14 Combustion chamber [0037] 15
Axis [0038] 16 Injection device [0039] 17, 18 Fuel feed line [0040]
19 Valve [0041] 20 Fuel lance [0042] 21 Vertical outer tube of the
fuel lance [0043] 21' Horizontal outer tube of the fuel lance
[0044] 22 Inner tube [0045] 23 Injection orifice [0046] 24 Fuel
[0047] 25 Air [0048] 26 Hot gas flow [0049] 27 Low-pressure
combustion chamber operated by means of self-ignition [0050] 28
Vortex generators [0051] 29 Fuel injection [0052] 30 Fuel injection
[0053] F1 Fuel (natural gas) [0054] F2 Fuel (H.sub.2-rich, for
example syngas) [0055] .alpha. Injection angle [0056] .alpha.'
Injection angle
* * * * *