Information
-
Patent Grant
-
6186775
-
Patent Number
6,186,775
-
Date Filed
Friday, January 22, 199925 years ago
-
Date Issued
Tuesday, February 13, 200123 years ago
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Inventors
-
Original Assignees
-
Examiners
- Lazarus; Ira S.
- Lee; David
Agents
- Burns, Doane, Swecker & Mathis, L.L.P.
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CPC
-
US Classifications
Field of Search
US
- 060 737
- 060 760
- 060 39826
- 060 39827
- 060 39828
- 431 8
- 431 10
- 431 9
- 431 284
- 431 285
- 431 254
- 431 258
- 431 263
- 431 264
- 431 265
- 431 351
- 431 352
- 431 353
- 431 354
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International Classifications
-
-
Disclaimer
Terminal disclaimer
Abstract
In a burner for operating a combustion chamber, which burner essentially comprises a swirl generator (100), a transition piece (200) arranged downstream of the swirl generator, and a mixing tube (20), transition piece (200) and mixing tube (20) forming the mixing section of the burner and being arranged upstream of a combustion space (30). A pilot-burner system (300) is arranged in the lower region of the mixing tube (20), which pilot-burner system (300), at minimized pollutant emissions, stabilizes the flame front, in particular in the transient load ranges. At least one ignition device (311) is integrated in the pilot-burner system (300).
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a burner for operating a heat generator.
2. Discussion of Background
EP-0 780 629 A2 has disclosed a burner which comprises a swirl generator on the incident-flow side, the flow formed herein being passed smoothly into a mixing section. This is done with the aid of a flow geometry, which is formed at the start of the mixing section for this purpose and consists of transition passages which cover sectors of the end face of the mixing section, in accordance with the number of acting sectional bodies of the swirl generator, and run helically in the direction of flow. On the outflow side of these transition passages, the mixing section has a number of prefilming bores, which ensure that the flow velocity along the tube wall is increased. This is then followed by a combustion chamber, the transition between the mixing section and the combustion chamber being formed by a jump in cross section, in the plane of which a backflow zone or backflow bubble forms.
The swirl intensity in the swirl generator is therefore selected in such a way that the breakdown of the vortex does not take place inside the mixing section but further downstream, as explained above, in the region of the jump in cross section. The length of the mixing section is dimensioned in such a way that an adequate mixture quality is ensured for all types of fuel.
Although this burner, compared with those from the prior art, guarantees a significant improvement with regard to intensification of the flame stability, lower pollutant emissions, lower pulsations, complete burn-out, large operating range, good cross-ignition between the various burners, compact type of construction, improved mixing, etc., it has been found that this burner has no autonomous measures in order to be able to reliably run the gas turbine in particular in its transient load ranges. For example, in the part-load range, the burner must be assisted with a back up flame. In this case, the integration of such measures in the burner must not lead to any additional pollutant emissions, which could jeopardize the operational and emissive advantages of the burner taken as a basis. There is also the fact that these burners, in gas turbines, are ignited in a conventional manner by means of a special igniter. These igniters usually operate at a high voltage, which delivers the ignition spark, which either serves directly as ignition source at high output or ignites an ignition torch. These igniters require a separate leadthrough and seal for the igniter and its conduits through the casing of the gas turbine right into the combustion chamber. However, the existing igniter systems have the following disadvantages:
a) costly separate leadthrough and seal for the igniter and its conduits through the casing of the gas turbine right into the combustion chamber;
b) cross-ignition inside the combustion chamber on account of the small number of igniters (usually only 1 igniter for reasons of cost);
c) thermal loading of the igniter due to the positioning in the combustion chamber, which, for example, requires cooling of the igniter, for which reason leakages occur due to seals which may be unsound;
d) highly susceptible to condensed water, in which case short circuits divert the ignition spark.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention, in a burner of the aforementioned type, is to propose novel measures which ensure intensification of the flame stability for a stable operation, in particular in the transient load ranges, always with the further proviso that the pollutant emissions remain low, and, at the same time, when these measures are taken, steps are to be taken which are able to remove the abovementioned disadvantages concerning ignition systems.
For this purpose, the burner is extended in such a way that an annular system which is intended for the provision of an air/fuel mixture and generally functions as a pilot stage is provided in the region of its transition to the combustion space arranged downstream. A number of outlet bores which are provided in the peripheral direction and lead into the combustion space create corresponding pilot burners, which for stability reasons are run by diffusion operation and act directly in the combustion space.
The essential advantages of the subject matter of the invention may be seen in the fact that these individual pilot burners are operated with a low proportion of gas, so that the gas introduced there mixes with a relatively small proportion of air and burns as premixed flame with minimized pollutant emissions.
This air quantity, with the aid of impingement cooling, first of all performs the task of cooling the side remote from the combustion chamber before it then mixes with the gas and subsequently, as premixed flame with minimized pollutant emissions, maintains the piloting of the combustion space.
Due to this impingement cooling, the surface of the pilot-gas ring is largely isolated from the hot gas and from the flame radiation from the combustion space, so that the thermal loading in this region is substantially reduced.
Even during 100% pilot operation, the individual pilot burners, for stability reasons, burn by diffusion operation, since here the proportion of cooling air compared with the gas is very small.
The subject matter of the invention also achieves the effect that the minimized cooling quantity can likewise be fed to the combustion process.
The directed introduction of said cooling air is at the same time used to provide an ignition device, integrated there, for the respective pilot burner, whereby this integrated ignition device for the pilot burner becomes a component part of the burner system, and this component part is interchangeably mounted in the gas turbine. Due to the integration of the ignition device in the burner, a plurality of pilot burners or all the pilot burners can be equipped with an igniter, as a result of which optimum cross-ignition properties are achieved. The pilot burner is preferably ignited by means of an incandescent ignition pin or by means of a spark plug.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1
shows a burner designed as a premix burner and having a mixing section downstream of a swirl generator and pilot burners,
FIG. 2
shows a schematic representation of the burner according to
FIG. 1
with the disposition of the additional fuel injectors,
FIG. 3
shows a perspective representation of a swirl generator consisting of a plurality of shells, in appropriate cut-away section,
FIG. 4
shows a cross section through a two-shell swirl generator,
FIG. 5
shows a cross section through a four-shell swirl generator,
FIG. 6
shows a view through a swirl generator whose shells are profiled in a blade shape,
FIG. 7
shows a configuration of the transition geometry between swirl generator and mixing section, and
FIG. 8
shows a breakaway edge for the spatial stabilization of the backflow zone.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, all features not essential for the direct understanding of the invention have been omitted, and the direction of flow of the media is indicated by arrows,
FIG. 1
shows the overall construction of a burner. Initially a swirl generator
100
is effective, the configuration of which is shown and described in more detail below in
FIGS. 3-6
. This swirl generator
100
is a conical structure to which a combustion-air flow
115
flowing in tangentially is repeatedly admitted tangentially. The flow forming herein, with the aid of a transition geometry provided downstream of the swirl generator
100
, is passed smoothly into a transition piece
200
in such a way that no separation regions can occur there. The configuration of this transition geometry is described in more detail with reference to FIG.
6
. This transition piece
200
is extended on the outflow side of the transition geometry by a mixing tube
20
, both parts forming the actual mixing section
220
. The mixing section
220
may of course be made in one piece; i.e. the transition piece
200
and the mixing tube
20
are then fused to form a single cohesive structure, the characteristics of each part being retained. If transition piece
200
and mixing tube
20
are constructed from two parts, these parts are connected by a sleeve ring
10
, the same sleeve ring
10
serving as an anchoring surface for the swirl generator
100
on the head side. In addition, such a sleeve ring
10
has the advantage that various mixing tubes can be used. Located on the outflow side of the mixing tube
20
is the actual combustion space
30
of a combustion chamber, which is symbolized here merely by a flame tube. The mixing section
220
largely fulfills the task of providing a defined section, in which perfect premixing of fuels of various types can be achieved, downstream of the swirl generator
100
. Furthermore, this mixing section, that is primarily the mixing tube
20
, enables the flow to be directed free of losses so that at first no backflow zone or backflow bubble can form even in interaction with the transition geometry, whereby the mixing quality for all types of fuel can be influenced over the length of the mixing section
220
. However, this mixing section
220
has another property, which consists in the fact that, in the mixing section
220
itself, the axial velocity profile has a pronounced maximum on the axis, so that a flashback of the flame from the combustion chamber is not possible. However, it is correct to say that this axial velocity decreases toward the wall in such a configuration. In order also to prevent flashback in this region, the mixing tube
20
is provided in the flow and peripheral directions with a number of regularly or irregularly distributed bores
21
having widely differing cross sections and directions, through which an air quantity flows into the interior of the mixing tube
20
and induces an increase in the rate of flow along the wall for the purposes of a prefilmer. These bores
21
may also be designed in such a way that effusion cooling also appears at least in addition at the inner wall of the mixing tube
20
. Another possibility of increasing the velocity of the mixture inside the mixing tube
20
is for the cross section of flow of the mixing tube
20
on the outflow side of the transition passages
201
, which form the transition geometry already mentioned, to undergo a convergence, as a result of which the entire velocity level inside the mixing tube
20
is raised. In the figure, these bores
21
run at an acute angle relative to the burner axis
60
. Furthermore, the outlet of the transition passages
201
corresponds to the narrowest cross section of flow of the mixing tube
20
. Said transition passages
201
accordingly bridge the respective difference in cross section without at the same time adversely affecting the flow formed. If the measure selected initiates an intolerable pressure loss when directing the tube flow
40
along the mixing tube
20
, this may be remedied by a diffuser (not shown in the figure) being provided at the end of this mixing tube. A combustion chamber
30
(combustion space) then adjoins the end of the mixing tube
20
, there being a jump in cross section, formed by a burner front
70
, between the two cross sections of flow. Not until here does a central flame front having a backflow zone
50
form, which backflow zone
50
has the properties of a bodiless flame retention baffle relative to the flame front. If a fluidic marginal zone, in which vortex separations arise due to the vacuum prevailing there, forms inside this jump in cross section during operation, this leads to intensified ring stabilization of the backflow zone
50
. In addition, it must not be left unmentioned that the generation of a stable backflow zone
50
also requires a sufficiently high swirl coefficient in a tube. If such a high swirl coefficient is undesirable at first, stable backflow zones may be generated by the feed of small, intensely swirled air flows at the tube end, for example through tangential openings. It is assumed here that the air quantity required for this is approximately 5-20% of the total air quantity. As far as the configuration of the burner front
70
at the end of the mixing tube
20
for stabilizing the backflow zone or backflow bubble
50
is concerned, reference is made to the description in connection with FIG.
8
.
A pilot-burner system
300
is provided concentrically to the mixing tube
20
, in the region of its outlet. This pilot-burner system
300
consists of an inner annular chamber
301
into which a fuel, preferably a gaseous fuel
303
, flows. Disposed in juxtaposition with this inner annular chamber
301
is a second annular chamber
302
into which an air quantity
304
flows. Both annular chambers
301
,
302
have individually configured through-openings in such a way that the individual media
303
,
304
, with respect to the function, flow into a common annular chamber
308
arranged downstream. The gaseous fuel
303
is passed from the annular chamber
301
into the downstream annular chamber
308
through a number of openings
309
arranged in the peripheral direction. The passage geometry of these openings
309
is configured in such a way that the gaseous fuel
303
flows with a large mixing potential into the annular chamber
308
arranged downstream. The other annular chamber
302
terminates with a perforated plate
305
, the bores
310
provided here being configured in such a way that the air quantity
304
flowing through there brings about impingement cooling on the base plate
307
of the annular chamber
308
arranged downstream. This base plate has the function of a heat-shield plate relative to the thermal loading from the combustion space
30
, so that this impingement cooling must turn out to be extremely efficient here. After the cooling has been carried out, this air mixes inside this annular chamber
308
with the gaseous fuel
303
flowing along from the openings
309
of the annular chamber
301
arranged upstream, before this mixture then flows off into the combustion space
30
through a number of bores
306
arranged on the combustion-space side. The mixture flowing out here burns as a premixed diffusion flame with minimized pollutant emissions and therefore forms for each bore
306
a pilot burner which acts in the combustion space
30
and ensures a stable operation.
An ignition device
311
is passed through the juxtaposed annular chamber
302
through which air flows, and this ignition device
311
, in the annular chamber
308
arranged downstream, ignites the mixture forming there. On the one hand, no further design measures are required in order to pass through the ignition device
311
, and, on the other hand, this ignition device
311
is constantly cooled by the air
304
flowing there in any case. This is very important, since, when using an incandescent ignition pin, temperatures of about 1000° C. are reached at the tip. However, since only a low voltage, and in return a high current, is required for the operation proposed here, the ignition device is not susceptible to condensed-water precipitation. By the arrangement of the incandescent ignition pin inside the burner, in which case the use of a spark plug is likewise possible, the respective ignition device
311
is subjected to low thermal loading, whereby it requires no additional cooling and leakages are thereby also avoided.
FIG. 2
shows a schematic view of the burner according to
FIG. 1
, reference being made here in particular to the purging around a centrally arranged fuel nozzle
103
and to the action of fuel injectors
170
. The mode of operation of the remaining main components of the burner, namely swirl generator
100
and transition piece
200
, are described in more detail with reference to the following figures. The fuel nozzle
103
is encased at a distance by a ring
190
in which a number of bores
161
disposed in the peripheral direction are placed, and an air quantity
160
flows through these bores
161
into an annular chamber
180
and performs the purging there around the fuel lance. These bores
161
are positioned so as to slant forward in such a way that an appropriate axial component is obtained on the burner axis
60
. Provided in interaction with these bores
161
are additional fuel injectors
170
which feed a certain quantity of preferably a gaseous fuel into the respective air quantity
160
in such a way that an even fuel concentration
150
appears in the mixing tube
20
over the cross section of flow, as the representation in the figure is intended to symbolize. It is precisely this even fuel concentration
150
, in particular the pronounced concentration on the burner axis
60
, which provides for stabilization of the flame front at the outlet of the burner to occur, whereby the occurrence of combustion-chamber pulsations is avoided.
In order to better understand the construction of the swirl generator
100
, it is of advantage if at least
FIG. 4
is used at the same time as FIG.
3
. In the description of
FIG. 3
below, the remaining figures are referred to when required.
The first part of the burner according to
FIG. 1
forms the swirl generator
100
shown according to FIG.
3
. The swirl generator
100
consists of two hollow conical sectional bodies
101
,
102
which are nested one inside the other in a mutually offset manner. The number of conical sectional bodies may of course be greater than two, as
FIGS. 5 and 6
show; this depends in each case on the mode of operation of the entire burner, as will be explained in more detail further below. It is not out of the question in certain operating configurations to provide a swirl generator consisting of a single spiral. The mutual offset of the respective center axis or longitudinal symmetry axes
101
b
,
102
b
(cf.
FIG. 4
) of the conical sectional bodies
101
,
102
provides at the adjacent wall, in mirror-image arrangement, one tangential duct each, i.e. an air-inlet slot
119
,
120
(cf.
FIG. 4
) through which the combustion air
115
flows into the interior space of the swirl generator
100
, i.e. into the conical hollow space
114
of the same. The conical shape of the sectional bodies
101
,
102
shown has a certain fixed angle in the direction of flow. Of course, depending on the operational use, the sectional bodies
101
,
102
may have increasing or decreasing conicity in the direction of flow, similar to a trumpet or tulip respectively. The two last-mentioned shapes are not shown graphically, since they can readily be visualized by a person skilled in the art. The two conical sectional bodies
101
,
102
each have a cylindrical annular initial part
101
a
. Accommodated in the region of this cylindrical initial part is the fuel nozzle
103
, which has already been mentioned with reference to FIG.
2
and is preferably operated with a liquid fuel
112
. The injection
104
of this fuel
112
coincides approximately with the narrowest cross section of the conical hollow space
114
formed by the conical sectional bodies
101
,
102
. The injection capacity of this fuel nozzle
103
and its type depend on the predetermined parameters of the respective burner. Furthermore, the conical sectional bodies
101
,
102
each have a fuel line
108
,
109
, and these fuel lines
108
,
109
are arranged along the tangential air-inlet slots
119
,
120
and are provided with injection openings
117
through which preferably a gaseous fuel
113
is injected into the combustion air
115
flowing through there, as the arrows
116
are intended to symbolize. These fuel lines
108
,
109
are preferably arranged at the latest at the end of the tangential inflow, before entering the conical hollow space
114
, in order to obtain optimum fuel/air mixing. As mentioned, the fuel
112
fed through the fuel nozzle
103
is normally a liquid fuel, a mixture formation with another medium, for example with a recycled flue gas, being readily possible. This fuel
112
is injected at a preferably very acute angle into the conical hollow space
114
. Thus, a conical fuel spray
105
, which is enclosed and reduced by the rotating combustion air
115
flowing in tangentially, forms from the fuel nozzle
103
. The concentration of the injected fuel
112
is then continuously reduced in the axial direction by the inflowing combustion air
115
to form a mixture in the direction of vaporization. If a gaseous fuel
113
is introduced via the opening nozzles
117
, the fuel/air mixture is formed directly at the end of the air-inlet slots
119
,
120
. If the combustion air
115
is additionally preheated or, for example, enriched with recycled flue gas or exhaust gas, this provides lasting assistance for the vaporization of the liquid fuel
112
, before this mixture flows into the downstream stage, here into the transition piece
200
(cf. FIGS.
1
and
7
). The same considerations also apply if liquid fuels are to be supplied via the lines
108
,
109
. Narrow limits per se are to be adhered to in the configuration of the conical sectional bodies
101
,
102
with regard to the cone angle and the width of the tangential air-inlet slots
119
,
120
so that the desired flow field of the combustion air
115
can develop at the outlet of the swirl generator
100
. In general it may be said that a reduction in the size of the tangential air-inlet slots
119
,
120
promotes the quicker formation of a backflow zone already in the region of the swirl generator. The axial velocity inside the swirl generator
100
can be increased or stabilized by a corresponding feed of an air quantity, this feed being described in more detail with reference to
FIG. 2
(item
160
). Corresponding swirl generation in interaction with the downstream transition piece
200
(cf.
FIGS. 1 and 7
) prevents the formation of flow separations inside the mixing tube arranged downstream of the swirl generator
100
. Furthermore, the design of the swirl generator
100
is especially suitable for changing the size of the tangential air-inlet slots
119
,
120
, whereby a relatively large operational range can be covered without changing the overall length of the swirl generator
100
. The sectional bodies
101
,
102
may of course be displaced relative to one another in another plane, as a result of which even an overlap of the same can be provided. Furthermore, it is possible to nest the sectional bodies
101
,
102
spirally one inside the other by a contra-rotating movement. It is thus possible to vary the shape, size and configuration of the tangential air-inlet slots
119
,
120
as desired, whereby the swirl generator
100
can be used universally without changing its overall length.
Inter alia, the geometric configuration of baffle plates
121
a
,
121
b
, which may be provided as desired, is now apparent from FIG.
4
. They have a flow-initiating function, in which case, in accordance with their length, they extend the respective end of the conical sectional bodies
101
,
102
in the incident-flow direction relative to the combustion air
115
. The ducting of the combustion air
115
into the conical hollow space
114
can be optimized by opening or closing the baffle plates
121
a
,
121
b
about a pivot
123
placed in the region of the inlet of this duct into the conical hollow space
114
, and this is especially necessary if the original gap size of the tangential air-inlet slots
119
,
120
is to be changed dynamically, for example in order to change the velocity of the combustion air
115
. These dynamic measures may of course also be provided statically by baffle plates forming as and when required a fixed integral part with the conical sectional bodies
101
,
102
.
FIG. 5
, in comparison with
FIG. 4
, shows that the swirl generator
100
is now composed of four sectional bodies
130
,
131
,
132
,
133
. The associated longitudinal symmetry axes for each sectional body are identified by the letter a. It may be said of this configuration that, on account of the smaller swirl intensity thus produced, and in interaction with a correspondingly increased slot width, it is best suited to prevent the breakdown of the vortex flow on the outflow side of the swirl generator in the mixing tube, whereby the mixing tube can best fulfill the role intended for it.
FIG. 6
differs from
FIG. 5
inasmuch as the sectional bodies
140
,
141
,
142
,
143
here have a blade-profile shape, which is provided for supplying a certain flow. Otherwise, the mode of operation of the swirl generator is the same. The admixing of the fuel
116
with the combustion-air flow
115
is effected from the interior of the blade profiles, i.e. the fuel line
108
is now integrated in the individual blades. Here, too, the longitudinal symmetry axes for the individual sectional bodies are identified by the letter a.
FIG. 7
shows the transition piece
200
in a three-dimensional view. The transition geometry is constructed for a swirl generator
100
having four sectional bodies in accordance with
FIG. 5
or
6
. Accordingly, the transition geometry has four transition passages
201
as a natural extension of the sectional bodies acting upstream, as a result of which the cone quadrant of said sectional bodies is extended until it intersects the wall of the mixing tube. The same considerations also apply when the swirl generator is constructed from a principle other than that described with reference to FIG.
3
. The surface of the individual transition passages
201
which runs downward in the direction of flow has a form which runs spirally in the direction of flow and describes a crescent-shaped path, in accordance with the fact that in the present case the cross section of flow of the transition piece
200
widens conically in the direction of flow. The swirl angle of the transition passages
201
in the direction of flow is selected in such a way that a sufficiently large section subsequently remains for the tube flow up to the jump in cross section at the combustion-chamber inlet in order to effect perfect premixing with the injected fuel. Furthermore, the axial velocity at the mixing-tube wall downstream of the swirl generator is also increased by the abovementioned measures. The transition geometry and the measures in the region of the mixing tube produce a distinct increase in the axial-velocity profile toward the center of the mixing tube, so that the risk of premature ignition is decisively counteracted.
FIG. 8
shows the breakaway edge already discussed, which is formed at the burner outlet. The cross section of flow of the tube
20
in this region is given a transition radius R, the size of which in principle depends on the flow inside the tube
20
. This radius R is selected in such a way that the flow comes into contact with the wall and thus causes the swirl coefficient to increase considerably. Quantitatively, the size of the radius R can be defined in such a way that it is >10% of the inside diameter d of the tube
20
. Compared with a flow without a radius, the backflow bubble
50
is now hugely enlarged. This radius R runs up to the outlet plane of the tube
20
, the angle β between the start and end of the curvature being <90°. The breakaway edge A runs along one leg of the angle β into the interior of the tube
20
and thus forms a breakaway step S relative to the front point of the breakaway edge A, the depth of which is >3 mm. Of course, the edge running parallel here to the outlet plane of the tube
20
can be brought back to the outlet-plane step again by means of a curved path. The angle β′ which extends between the tangent of the breakaway edge A and the perpendicular to the outlet plane of the tube
20
is the same size as angle β. The advantages of this design of this breakaway edge can be seen from EP-0 780 629 A2 under the section “SUMMARY OF THE INVENTION”. A further configuration of the breakaway edge for the same purpose can be achieved with torus-like notches on the combustion-chamber side. As far as the breakaway edge is concerned, this publication, including the scope of protection there, is an integral part of the present description.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
Claims
- 1. A burner useful for operating a heat generator comprising:a swirl generator having an upstream end, a downstream end, and defining a flow axis between the upstream and downstream ends, the swirl generator conducting a combustion-air flow therethrough at least partially downstream; means for injecting at least one fuel into the combustion-air flow; a mixing section positioned downstream of the swirl generator and including a upstream part and a mixing tube downstream of the upstream part, the upstream part including at least one transition passage passing the swirl generator flow into the mixing tube, the mixing tube including a downstream part; an annular pilot-burner system arranged around the mixing tube downstream part, the pilot-burner system comprising at least a first annular chamber, a second annular chamber, and a third annular chamber, wherein said second chamber is positioned at least in part concentrically around said first annular chamber, and at least a part of said third annular chamber is positioned downstream and adjacent said first and second annular chambers; wherein the pilot-burner system includes a downstream wall adjacent to the third annular chamber, the downstream wall comprising a heat shield plate; wherein the pilot-burner system includes a plate having axially oriented perforations, the second annular chamber being divided from the third annular chamber by the plate, the plate causing air flow entering the second annular chamber to form jets of air to provide impingement cooling for the heat shield when air flows through the second annular chamber; wherein the pilot-burner system includes at least one throughflow opening fluidly communicating the first annular chamber with the third annular, the at least one throughflow opening causing a gaseous fuel flow entering the first annular chamber to flow into the third annular chamber and form an air/fuel mixture with the air when air flows through the second annular chamber and fuel flows through the first annular chamber; wherein the heat shield plate includes at least one circumferentially arranged opening which causes the air/fuel mixture to flow from the third annular chamber downstream and to burn as pilot flames when air flows through the second annular chamber, fuel flows through the first annular chamber, and the air/fuel mixture is ignited.
- 2. The burner in accordance with claim 1, further comprising at least one igniter positioned in said third annular chamber.
- 3. The burner in accordance with claim 2, wherein the igniter comprises a spark plug.
- 4. The burner in accordance with claim 2, wherein the igniter comprises an incandescent ignition pin.
- 5. The burner in accordance with claim 2, wherein the igniter extends through the second annular chamber.
- 6. The burner in accordance with claim 1, further comprising a fuel nozzle and a ring, the ring being arranged upstream of the swirl generator, wherein the ring includes at least one bore, and further comprising means for injecting a fuel into an air quantity flowing through the at least one bore.
- 7. The burner in accordance with claim 6, wherein the at least one bore is directed so as to slant at least in part downstream.
- 8. The burner in accordance with claim 6, further comprising an annular air chamber surrounding the fuel nozzle.
- 9. The burner in accordance with claim 1, wherein the mixing tube includes a burner front at a downstream end of the mixing tube, the burner front including a separation edge.
- 10. The burner in accordance with claim 1, wherein the swirl generator forms at least one partial flow, and wherein the number of the at least one transition passage is the same as the number of the at least one partial flow.
- 11. The burner in accordance with claim 1, wherein the mixing tube includes an interior and openings oriented axially at least in part and in a direction orthogonal to the axial direction for injecting an air flow into the interior of the mixing tube.
- 12. The burner in accordance with claim 11, wherein the mixing tube openings extend at an acute angle relative to the flow axis.
- 13. The burner in accordance with claim 1, wherein the mixing section has a cross-sectional area of flow, and further comprising a combustion chamber having a cross-sectional area of flow and positioned downstream of the mixing section, wherein there is a jump in cross-sectional area of flow between the mixing section and the combustion chamber, which jump in cross-sectional area of flow permits backflow zone to form in the region of the jump.
- 14. The burner in accordance with claim 1, wherein the swirl generator comprises at least two hollow, conical sectional bodies which are nested one inside the other in the direction of flow, each of the at least two hollow, conical sectional bodies having walls and symmetry axes, the symmetry axes being offset to each other so that the adjacent walls of the sectional bodies form ducts, tangential in their longitudinal extent, for a combustion-air flow, the at least two hollow, conical sectional bodies together defining an interior space, and further comprising at least one fuel nozzle oriented to inject fuel into the interior space formed by the at least two hollow, conical sectional bodies.
- 15. The burner in accordance with claim 14, further comprising fuel nozzles arranged adjacent to the tangential ducts in their longitudinal extent.
- 16. The burner in accordance with claim 14, wherein the at least two hollow, conical sectional bodies each have a blade-shaped profile in cross section.
- 17. The burner in accordance with claim 14, wherein the at least two hollow, conical sectional bodies each have increasing conicity in the direction of flow.
- 18. The burner in accordance with claim 14, wherein the at least two hollow, conical sectional bodies are nested spirally one inside the other.
Priority Claims (1)
Number |
Date |
Country |
Kind |
98810037 |
Jan 1998 |
EP |
|
US Referenced Citations (12)
Foreign Referenced Citations (6)
Number |
Date |
Country |
0543323A2 |
May 1993 |
EP |
0670456A1 |
Sep 1995 |
EP |
0710797A2 |
May 1996 |
EP |
0728989A2 |
Aug 1996 |
EP |
0780629A2 |
Jun 1997 |
EP |
0797051A2 |
Sep 1997 |
EP |