JPH08240129A - Combustion apparatus for gas-turbine engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stability of a lean burn combustion process over a wide range of engine load conditions by composing a fuel injeciton means so as to injet the fuel to columnar air inside a combustor and outside a burner. SOLUTION: A pilot burner 114 injects air as a swirling column from a circular slot 302 in a burner head 214 to establish a divergent columnar shear layer 303. The fuel is injected toward the columnar shear layer 303 for mixing with the air in the shear layer 303. Main burners 120, 122 inject fuel-lean main air-fuel mixture toward the columnar shear layer for establishing a combustion region. It is thus possible to improve stability of lean combustion type combustion process in a wider range of a load condition of an engine, particularly to suppress generatin of pollution material under patial load condition of a gas turbine.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to gas turbine engine combustors (also referred to simply as "gas turbine combustors") including associated fuel burners and igniters.
In particular, the present invention relates to a combustor suitable for maintaining a lean burn type combustion (combustion in a state where the air-fuel mixture has a small fuel content).

[0002]

Gas turbines operate over a wide range of engine speed / load conditions from initial starting conditions through various engine speed / load combination conditions to maximum load.
In general, a combustion apparatus for a gas turbine must have members having functions of fuel injection, ignition, and at least maintenance of a pilot flame after the ignition. The present invention contemplates improvements in combustion devices with respect to such components.

Lean combustion type combustion (a combustion method in which a larger amount of air is mixed with fuel than in the case of a combustor using a diffusion combustion type combustion flame in the upstream of the combustion zone, that is, a combustion method in which a lean air-fuel mixture with less fuel is burned In the low power range, the combustion process has a lower limit of combustible concentration of the air / fuel mixture (also referred to as “air-fuel mixture” or “mixture”) (lower limit of combustible fuel concentration, That is, it is well known that it is difficult to ensure the stability of the flame, since it is performed at a temperature close to the lower limit concentration below which the fire disappears). Therefore, at high power, a main fuel injector or burner is used to produce a fuel lean air / fuel mixture (also referred to simply as "fuel lean mixture" or "lean mixture") for lean burn type combustion. When operated at low power, when the lean burn type combustion process is likely to become unstable, a fuel rich air / fuel mixture for diffusion combustion type combustion (simply “fuel rich mixture” or “rich mixture”) A combustion device adapted to operate a pilot fuel injector or burner is also employed to produce The pilot burner is used not only to initiate (ignite) combustion, but also to maintain lean burn type combustion during engine start-up and partial load (less than full load or less than 100% load) conditions. The fuel supply is gradually transferred from the pilot burner to the main burner as the stability increases. Unfortunately, however,
The use of such pilot burners causes undesired pollutants due to the rich mixture in the partial load conditions of the gas turbine.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a burner, especially a pilot burner, capable of increasing the stability of a lean burn combustion process over a wide range of engine load conditions. It is to suppress the generation of pollutants under the partial load condition of the turbine. An example of a lean burn combustor for a gas turbine is shown in British patent specification GB 2287312 A, in particular FIGS. This patent discloses a series stage multi-stage combustor, the first stage (first stage) of the combustor consisting of a small diameter combustion chamber with a pilot burner located on the longitudinal centerline. A premixing main burner for radially injecting the premixed vortex air-fuel mixture into the chamber is located downstream of the pilot burner and radially outward thereof. When the combustor is ignited, pilot fuel is injected from the central portion of the pilot burner and ignited by the igniter arranged at the center of the pilot burner. In parallel with this, a part of the pilot fuel is mixed with air in the pilot burner, ejected from the peripheral portion of the pilot burner as a premixed vortex air-fuel mixture, and is placed near the wall of the combustor. Is ignited by. The purpose of this combustor is to mix a premixed vortex air-fuel mixture with a fuel spray in a small combustion chamber in order to set up a diffusion-rich combustion flame that is stable and has a high fuel concentration during ignition. Then, as the amount of fuel supplied to the combustor is increased to increase the power of the turbine, the fuel flow to the pilot nozzle, starting from the supply to the central part of the pilot nozzle (pilot burner), is transferred to the main burner. Therefore, the complete lean burn combustion mode is started as soon as possible.

The structure of the above-mentioned British patent is claimed to allow low NOx (low emission of nitrogen oxides) combustion over the full load range of the gas turbine, but one drawback is stable. It appears to be due to the large number of ignition sources required to maintain combustion. In that patent, as shown in its FIGS. 3 and 4, four so-called "microburners" are provided as ignition sources for the first smallest diameter combustion zone of the combustor. This structure adds to the combustor design complexity and increases manufacturing costs. Further, it is well known that the igniter of a gas turbine combustor can suffer significant damage if continuously exposed to the heat generated in the operating combustor.

Accordingly, another object of the present invention is to provide at least a majority (50) of fuel supply under low load conditions of a gas turbine.
% Or more) can be transferred from the diffusion combustion type combustion process to the lean combustion type combustion process, and has sufficient memorandum stability to enable the use of a single simple ignition source,
A lean burn type combustion apparatus and a lean burn type combustion maintaining method.

In order to reduce cost and complexity, and to facilitate manufacturing and maintenance, it is desirable to minimize the required number of separate combustion stages incorporated in the combustor.
Therefore, another object of the invention is to work in concert with each other,
Maintaining stable lean burn type combustion over a wide range of engine power using a single pilot burner and a single main burner respectively injecting a rich fuel mixture and a lean fuel mixture into the combustor. It is to provide a lean burn type combustion device capable of achieving the above.

Also, to reduce cost and complexity, the separate components needed to maintain combustion in both diffusion and lean burn modes, such as burner components and It is desirable to minimize the number of associated fuel passages and pipes, etc.).
Accordingly, another object of the present invention is to provide a burner structure for a gas turbine combustor that conveniently and conveniently combines the components of the pilot burner and the main burner into a combustor head.

[0009]

In order to solve the above problems, according to a first aspect of the present invention, a combustor for a gas turbine having a burner head comprising separate fuel injection means and air injection means is provided. Of the fuel injection means enclosing the air injection means in a substantially concentric relationship therewith, the air injection means having an annular cross-section (hollow).
Is configured to eject an air column and the fuel injection means is configured to inject fuel towards it for mixing with the air column outside the burner within the combustor. A burner characterized by. In a practical embodiment, the air column is divergent from the burner.

In a preferred embodiment, the air injection means may comprise means defining a circular slot in the burner head. However, the circular slot does not excessively impair the circumferential continuity of the air column,
It may be divided into a plurality of closely spaced holes that assemble to define a near circular shape. Furthermore, in a particularly preferred embodiment, the air injection means comprises means for imparting a swirl component to the air column. Such vortices cause a plurality of supply passages to open obliquely through the bottom wall of the complete circular slot, preferably tangentially to the side wall of the slot, at the bottom of the slot to allow air to flow through the supply passages. It can be created by feeding to the bottom of the slot.

In a preferred embodiment of the fuel injection means, an annular hole is formed near the periphery of the burner head, and the fuel is ejected from the burner through the hole. This hole is
It can be defined by an annular lip spaced from and covering the outermost peripheral edge of the burner head, causing fuel to be ejected from the burner through between the burner head and the lip. The injection of fuel can also be carried out through a circular array of holes formed in the burner head below the lip, the lip being provided with an air column to mix the fuel injected from the holes with the air column. Works to direct the person. In this preferred embodiment, the burner is combined with an igniter, such as an electric igniter or a catalytic igniter, and the igniter is housed with the air injection means in the interior region of the burner head.

In a second aspect of the invention, a burner system for a lean burn combustor for a gas turbine engine is provided. The combustor is composed of a combustor head incorporating a burner device, a combustion prechamber, and a main combustion chamber in order viewed in the flow direction of the combustion gas, and the combustion prechamber has a cross-sectional area considerably smaller than that of the main combustion chamber. . The burner apparatus of the present invention for use in this type of combustor comprises (a) a pilot burner located in the combustor head to maintain diffusion combustion type combustion in the prechamber, and (b) fuel concentration. For injecting a lean air-fuel mixture into the pre-chamber, and for providing a fuel injection means and an inward swirling motion to the air-fuel mixture when injected into the pre-chamber. A main burner including a swirler disposed radially outward thereof downstream of the pilot burner, the main burner having a body portion contained in a combustor head, the body portion comprising a fuel injection means. Has a plurality of fuel supply passages for supplying fuel to the main burner, and the swirler is attached to the main body of the main burner to form a peripheral edge of the most upstream portion of the prechamber.
The pilot burner fits within the body portion of the main burner.

In a third aspect of the present invention, a lean burn combustor for a gas turbine engine is provided. This combustor has a pilot burner and a main burner surrounding the pilot burner downstream of the pilot burner and for injecting an air-fuel mixture for combustion in the combustor. The pilot burner is configured to separately inject pilot fuel and air into the combustor at the same time and mix them in the combustor, where the air has a cross-sectional annular shape of a fluid flow surrounding an area proximate to the pilot burner. Air injection means for injecting into the combustor as (hollow) columnar shear layers (hereinafter also simply referred to as "shear layers");
Fuel injection means is provided for injecting the pilot fuel toward the shear layer for mixing with the air in the shear layer. The main burner is configured to inject a lean fuel-rich main air-fuel mixture into the combustor towards a columnar shear layer, which sets up a protected combustion zone, It works to improve the stability of lean burn type combustion in the combustor. This column-shaped shear layer is advantageously in the form of diverging from a pilot burner (trumpet shape). The pilot fuel injection means preferably surrounds and is substantially concentric with the air injection means.

In the invention of the third aspect, it is advantageous that the air injection means of the pilot burner is configured to give a swirling flow component to the air column forming the columnar shear layer. It is very advantageous if the main burner is also configured to add a swirling flow component to the main air-fuel mixture. In that case, it is desirable that the directions of the vortexes provided by the pilot burner and the main burner are opposite to each other.

In a fourth aspect of the present invention, there is provided a method of maintaining a lean burn type combustion process within a gas turbine engine combustor over a wide range of load conditions of the engine. This method consists of the following operations cooperating in sequence with one another: (A) an operation of injecting air into the combustor to create a columnar shear layer having an annular cross section of the fluid flow in the combustor, (b) a region surrounding the columnar shear layer from the region surrounding the column A pilot fuel substantially uniformly into a cylindrical (conical or cylindrical) base portion and entrained by the shear layer into the combustor for mixing with air in the shear layer for pilot air-fuel mixing. An operation of producing air, (c) a lean fuel main air space for maintaining a lean burn type combustion process in the combustor over a wide load condition range of the engine (at least at start-up and at full load conditions). Injecting the fuel-air mixture substantially uniformly from the region surrounding the columnar shear layer downstream of the pilot fuel injection region toward the shear layer, the main air-fuel mixture in the shear layer Operation of mixing with the pilot air-fuel mixture, (d Within a protected area that is surrounded and protected by the shear layer near the circular base portion of the shear layer and that has a flow velocity that is significantly slower than the proximal region in the shear layer and the proximal region beyond the shear layer. An operation of recirculating a part of the air-fuel mixture from the shear layer, and (e) burning the recirculated air-fuel mixture in the protection area to set a protected combustion area. Burning the recycled air-fuel mixture in a stable manner within the protected combustion zone,
Thereby, the operation of stabilizing the entire lean burning combustion process.

As in the third aspect of the invention, the fourth aspect
Also in the aspect of the invention, the column-shaped shear layer should diverge in the jet direction of air, and preferably has a rotating vortex flow component of the fluid flow around the center of the annular cross section of the shear layer. The main air-fuel mixture also preferably has a rotating vortex flow component of the fluid flow around the center of the shear layer. In that case, it is preferable that the direction of the vortex flow of the column-shaped shear layer and the direction of the vortex flow of the main air-fuel mixture are opposite to each other.

The relative amounts of air, pilot fuel, and main fuel injected into the combustion chamber are such that the air-fuel mixture in the above-mentioned protective combustion region is the entire amount in the combustor during engine startup and partial load conditions. In the combustion process as described above, that is, in the entire combustion process in the combustor, the fuel concentration should be changed so as to maintain stable combustion. In order to minimize the generation of pollutants over a wide range of engine operating conditions that vary from start-up to partial load to full load (maximum load), the overall combustion process (hereinafter (Also referred to simply as "overall combustion process") should be changed from fuel rich combustion to lean fuel combustion and for that purpose the amount of pilot fuel injected as part of the total injected fuel is From a small percentage of time (ratio significantly lower than 50%) to a large percentage at full speed / minimum load (when speed is maximum and minimum load) (higher than 50% of total injected fuel) Further, it is changed up to a 0% ratio at full speed / full load (when both speed and load are maximum). By providing a protected combustion zone, the transition from fuel rich combustion to lean fuel combustion in the overall combustion process can be accelerated.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, a combustor 100 of a gas turbine engine is the applicant's UK patent application GB9500, which is the Paris Convention priority document of the present application.
627.6 (Japanese Patent Application No. 7- filed on Dec. 19, 1995), which is generally similar in construction. The combustor 100 has several combustor cans 102 (only one shown in the figure) arranged around the circumference of the gas turbine engine. Each combustor can (hereinafter also simply referred to as “can”) 102 has a main combustion having a relatively large inner diameter D over most of its axial length when viewed along the longitudinal axis or centerline CL of the can. A chamber 103 is defined. The main combustion chamber 103 sharply narrows to a small inner diameter d near the upstream end of the combustor, that is, the head end, and defines a so-called pre-chamber 141 of the can 102. Although the present invention is described herein as having a generally cylindrical combustor can, it is not necessarily so limited and may be applied to, for example, an annular type combustor.

Each combustor can 102 includes a gas fuel injector assembly or burner device 104 that includes the head of the combustor 100 and a portion of the prechamber 141. Within the fuel injector assembly 104, there is a main burner 118 and a pilot burner 114 fitted within a central bore 116 of the main burner 118. A cylindrical central igniter 110 is arranged in the central inner hole 112 of the pilot burner 114 on the center line CL of the can 102. Primary burner 118
Is a fuel introduction main body (hereinafter, also simply referred to as “main body”) 1
20 and a swirler 123 fixed to the rear surface (downstream surface) 124 of the main body 120. In the swirler 123,
A plurality of swirl passages 122 are formed by machining. The vortex flow passage 122 extends to the circumference of the pre-chamber 141 so that the flow ejected therefrom has both radial and tangential velocity components with respect to the pre-chamber 141. The swirler 123 is arranged radially outward of the pilot burner 114, in a concentric relationship therewith, and immediately downstream (rearward) thereof, and the prechamber 14
1 defines the outermost perimeter of the most upstream portion. For details of the swirler similar to the swirler 123, see the above-mentioned British Patent Application GB950062.
7.6.

In operation, the air-fuel mixture ejected from the burner is combusted in the combustion zone 106 indicated by the straight broken line. The longitudinal axis of the combustion zone 106 is approximately can 10.
It coincides with the center line CL of 2. In fact, the dashed line 106 is
It is close to the flame front portion in the can 102. The true shape of the flame front is probably bell-shaped, as indicated by dashed line 106 ', with the most widened portion of the bell extending downstream from the outlet of prechamber 141. The base region or sub-zone 107 of the combustion zone 106 is near the pilot burner 114 within the fuel injector assembly 104 as shown by the cross hatched prechamber 141.
It is located inside. The overall combustion process in the combustor can 102 is initiated and maintained by combustion of the fuel rich air-fuel mixture in the base region 107 at startup and at low engine load, as described below. The air-fuel mixture burned in the region 107 is a rich air-fuel mixture in order to ensure stable combustion under such an engine load.
However, at least under relatively high partial load and full load (maximum load) conditions of the engine, the entire combustion process is a lean burn type combustion, and most of it is a large region of the combustion zone in the main combustion chamber 103. (50 of the entire combustion zone
% Area larger than 100%).

A pilot fuel supply passage 126 and a main fuel supply passage 128 are provided in the pilot burner 114 and the main burner 118, respectively, and a pilot air supply passage for the pilot burner 114 is also provided. For simplicity of illustration, details of the fuel and air supply passages for the pilot burner 114 are shown in FIG.
Although not shown in FIG. 2, it will be described later with reference to FIGS.

The operation of the main burner 118 will be described. The main gas fuel supply passage 128 in the fuel introduction body 120.
Supplies fuel to the first manifold or communication passage 130. The first manifold 130 is connected to the second manifold 132 via a plurality of perforations 131, from which fuel passes through the plurality of perforations 134 to the rear surface 1 of the body 120.
24 directly to the inlet of the swirl passage 122 of the swirler 123,
Alternatively, it is injected from the injector bar 136 to the inlet of the swirl passage 122. Thus, the gas fuel is vortex passage 122.
Easily mixes with the compressed air 138 flowing inwardly toward the centerline CL of the can 102. The relative amount of air to fuel is such that it produces a lean mixture. The swirl passage 122 imparts a rotating or swirling motion to the air-fuel mixture 139 passing therethrough, and when the air-fuel mixture exits the swirl passage, it becomes a swirl in the axial and radial directions around the centerline CL of the can. It flows toward the combustion zone 106. The air 138 for the main burner 118 is located in the area 1 surrounding the combustor can 102.
40 and is fed in a conventional manner from a gas turbine compressor (not shown).

When fuel and air exit swirler 123,
Not fully mixed (especially if high engine power is required and the amount of fuel and air to be mixed is relatively large) and still not ready to burn in a lean burn process. Requires time for equilibration. As mentioned above, the combustor can has a small diameter pre-chamber 141 of diameter d, and the length L of the small diameter portion 141 is reduced due to the lean burn type combustion performed in the large region 108 downstream thereof. But gives the additional time needed for thorough mixing.

It is customary to prevent the combustion process from propagating to the flow of air-fuel mixture from the main burner 118 or causing a "flashback" and backflow to impinge on the swirler 123. This is because when the flashback occurs, the heat of combustion damages the swirler 123 and other parts of the burner. The small diameter prechamber portion 141 of the can acts as a “ventilator” by performing a Venturi-like function so that the downstream velocity of the mixture after exiting the swirl passage is faster than the upstream velocity of the combustion process. The phenomenon can be prevented. Furthermore, the high velocity swirl of the lean fuel mixture in the prechamber 141 serves to keep the combustion process in the base region 107 of the combustion zone away from the walls of the prechamber 141.

The support of the combustor can 102 in the engine is
The rear or downstream end (not shown) is fixed in a known manner through the jet nozzle of the combustor to a suitable stationary structure of the engine (eg, nozzle guide vanes at the inlet to the high pressure turbine). Fuel injector assembly 1 at the head end side
This can be conveniently done by fixing 04 to a portion of the combustor casing 142. Casing 142
Has an opening for receiving and securing the main burner body 120. The connection of the can 102 to the casing 142 is
This is done by fixing the upstream flange 144 of the can to the rear surface of the ring 145 attached to the swirler 123.
The components of the fuel injector assembly 104 can be fixed to each other and to the casing 142 in a conventional manner with setscrews, bolts, and the like.

FIG. 2 is a sectional view of a part of the igniter 110, the pilot burner 114 and the main burner 118.
The path followed by fuel 200 through pilot burner 114 is indicated by an arrow. For simplicity of illustration, the air flow path for the pilot burner 114 has been omitted in FIG. 2 and is shown separately in FIG. FIG. 3 shows a flow pattern of fuel and air injected from the pilot burner 114. As shown in FIG. 2, power is supplied to the igniter 110 via a threaded coaxial cable socket 146 provided at the front end of the igniter 110. The socket 146, when fully screwed into the threaded portion 148 of the central bore 112 of the pilot burner 114, serves to squeeze the compression collar 150 onto the end of the igniter 110, igniter 110 and pilot burner 1.
14 to prevent relative movement.

As seen in FIG. 2, the igniter 110 is
A rigid center wire electrode 202, an inner insulating ceramic layer 204 surrounding the center electrode 202, and an inner insulating layer 204
A rigid metal sheath 206 surrounding the metal sheath 206 and an outer insulating ceramic layer 208 surrounding the metal sheath 206 and in contact with the wall of the central bore 112 of the pilot burner 114. The metal sheath 206 comprises a small electrode 210 at its rear end, which defines a spark gap with the end of the center electrode 202 adjacent to it. The air-fuel mixture is circulated across this spark gap, as described below,
It is ignited when a spark occurs in the spark gap.

The pilot burner 114 is shown in FIGS.
As shown in FIG. 2, a burner that interacts cooperatively with the main burner 118 is constructed, and both cooperate to achieve a uniform fuel supply and good flame stability within the base region 107 of the combustion zone, Igniter 11 heated by the process
It also has the function of appropriately cooling 0. In the pilot burner 114, the pilot fuel 200 passes through the pilot fuel supply passage 126 and the annular manifold 21.
1 and from there through a plurality of fuel passages 212 into another manifold 213. Fuel 200 is jetted from the burner head or rear surface 214 of pilot burner 114 through a circular array of holes 215 drilled to communicate with manifold 213 near its perimeter. Fuel 200 is pilot burner 114
As soon as it is ejected from the head through the hole 215, it is deflected along the burner surface 214 by a deflection lip 216 provided on a sleeve 218 brazed to the end of the pilot burner 114. As shown in FIG. 3, after being deflected by the deflecting lip 216, the pilot fuel 200 is curtained of high pressure air 300 that is expelled rearward from a circular groove or slot 302 formed in the burner surface 214. Merge into an annular (hollow) column. At this point, the turbulent flow caused by the flow of the pilot fuel 200 crossing the air 300 starts the mixing of the pilot fuel 200 and the air 300. The air 300 first entrains the fuel 200 in a direction away from the pilot burner 114, and is a divergent (trumpet) columnar shear layer 303 that is hollow (that is, annular in cross section) around the centerline CL of the combustor can 102. (Fig. 3) is set. In order to create a good pilot fuel and air mixture, the pilot fuel 200 is configured to be injected substantially uniformly into the circumference of the column of air 300 that forms the base portion of the shear layer 303. Has been done.

The shear layer 303 can be identified as defining the boundary between the combustion zone 106 (FIG. 1) and the flame front 106 'within the combustion chamber, but over a wide range of engine load conditions within the combustor. It is important to achieve the purpose of maintaining lean burn type combustion. The fuel-lean main air-fuel mixture is injected substantially uniformly from the vortex passage 122 surrounding the shear layer 303 toward the shear layer 303, and within the shear layer 303, the main air-fuel mixture and the pilot air-fuel mixture are injected. It should be noted that some mixing of The next part of the process is to recirculate some of the air-fuel mixture from all parts of the shear layer 303 towards the igniter 110, as indicated by arrow 304.
Such recirculation occurs because the ejection of air from slot 302 creates a region of slightly lower pressure near igniter 110. When the engine is started, the recirculated air-fuel mixture has a high fuel concentration, and after ignition, it burns with a stable flame in the base region 107, and the flame seems to be "anchored" in the slot 302 at first sight. And is surrounded by the air column 300 / shear layer 303. Even as the amount of fuel-lean mixture injected from the main burner 118 into the can 102 increased as engine speed and load increased, the slot 302 or at least its radially inner edge was recirculated. It is considered to act to stabilize the combustion process in the air-fuel mixture. Air column 300 / shear layer 303
Proximal to the proximal portion of the shear layer 303 and surrounding it by the shear layer is a recirculating root region 107 having a significantly slower flow velocity than the proximal region in and above the shear layer. it is obvious. By setting a stable combustion in this protected combustion area 107, the combustor can 102 including lean combustion type combustion in the large area 108.
The entire combustion process therein is stabilized under partial and full load (maximum load) conditions of the gas turbine engine.

Although not considered essential in any design of the combustion chamber and burner according to the present invention, the air 300 ejected from the slots 302 of the pilot burner head causes the swirl passage 1 of the main burner 118 to
It is highly preferable to have a vortex (rotation) motion component having a vortex direction opposite to that of the vortex motion component of the air-fuel mixture created by 22. To impart a swirling motion to the air 300, the air 300 passes through an array of perforations 306 formed obliquely to the sidewalls of the slot 302 so as to be generally tangential to the circumference of the slot 302. Feed to the bottom of slot 302. (The diagonal orientation of the perforations 306 is not shown in FIG. 3 for simplicity of illustration.) The perforations 306 are shown in the sleeve 21.
8 and is connected to the manifold 308. Manifold 308 may be supplied with air from a number of air passages or perforations 310, which may take air from swirl passage 122 as shown, or may be provided on the outer circumference of swirler 123. The air introduced through the conduit through the opening may be taken in. In the latter case, the higher "stagnation" pressure present on the outer circumference of the swirler 123 can be utilized and also the inclusion of fuel from the swirl passage 122 can be avoided.

The manifold 308, which supplies air to the circular slot 302, also supplies additional air to directly cool and protect the igniter 110, as shown in FIG. The air from the manifold 308 is perforated 310.
Through an annular air feed slot 312 cut into the pilot burner bore 112. This air is delivered from the outlet end of a series of short axial air channels or grooves 314 that are evenly spaced or otherwise formed into the bore 112 of the pilot burner. Erupted. Air channel 31
4 directs air from the air supply slot 312 along the sidewall of the hot end of the igniter 110 as shown,
Heat is removed from the hot end of 10. Channel 314
Projecting slightly beyond the rear end of the electrode 202 of the igniter 110, cooling air is thus expelled from the outlet end of the channel 314 over the end of the igniter 110, thereby cooling the igniter, Protects the igniter from the heating effects of the pilot flame base. The igniter cooling air has a region 107
It may have a diluting effect on the air-fuel mixture within it and should be taken into account in calculating the optimum air-fuel ratio for various engine speeds and loads.

The igniter cooling structure described above is only one of several possible alternative structures for implementing igniter cooling. For example, instead of forming an air supply slot 312 and an air channel 314 in the wall of the pilot burner bore 112, the end of the igniter 110 may have an outer flange at each end and be within the widened portion of the bore 112. It can be held in a small attached sleeve. In this configuration, the annular space defined between the bore 112 and the flange of the sleeve replaces the air supply slot 312,
A plurality of holes drilled in the flange at the end of the sleeve near the pilot flame replaces the air channel 314. A suitable lip is preferably provided on the face of the pilot burner just above the hole in the flange to modify the air across the jet end of the igniter.

In summary of the above-mentioned combustor / burner structure, the combustor is divided into a downstream main combustion chamber and an upstream prechamber, and a prechamber using a premixing swirler of the main burner. The outermost portion of the outer circumference of the is defined. The swirler receives fuel from a fuel introduction body that forms part of the combustor head to which it is attached. The pilot burner 114 is fitted within the fuel introduction body of the main burner in the combustor head. The igniter 110 is located within the pilot burner 114 rather than elsewhere in the combustion system. This structure greatly simplifies the device,
The objectives of simplifying the manufacture of the device, improving efficiency and miniaturization are achieved.

The above-described main burner 118 / pilot burner 114 / igniter 110 combination is used in the combustion region 1
As it stabilizes the combustion at 07, the pilot burner and the main burner mutually cooperate to maintain a lean burn type combustion over a wider range of engine operating powers and velocities conventionally possible in this type of combustor. It can be operated in a complementary manner. The table below shows by way of example the manner in which the total fuel supply can be distributed between the pilot burner and the main burner over the entire operating range of the engine used for power generation.

[0035]

[Table 1]

As can be seen from this, the relative amounts of air, pilot fuel and main fuel injected into the can 102 are
At engine start-up and under partial load conditions, the air-fuel mixture in the protected combustion zone 107 is modified to have sufficient fuel concentration to maintain stable combustion throughout the combustion process. It Most of the combustion process is performed in the lean burn type combustion mode within the large region 108 of the combustion zone even under a partial load condition. As the engine operating conditions change from start-up to partial load to full load (maximum load), the combustion process in the combustor generally changes to fuel rich combustion and lean fuel combustion. . When the engine is at full speed, the amount of pilot fuel injected as part of the total injected fuel is large at full speed / minimum load (at full speed and minimum load) (70% of total injected fuel). ) To almost 0% at full speed / maximum load (at maximum load at full speed). The overall combustion process is a somewhat fuel rich combustion at low load, but it is only a transient condition for most industrial engines operating at high load or full load (maximum load) for most of the time. . Therefore, it is possible to easily comply with the environmental protection regulations. In a test, the burner / combustor configuration of the present invention described above was able to stop the transition of the fuel supply from the pilot burner to the main burner, and correspondingly from the fuel rich combustion type low load combustion of the overall combustion process to the fuel. It has been found that the transition to lean burn high partial load and full load combustion can be accelerated.

In the example shown, the pilot air supply slot 302 is located on the face 21 of the pilot burner 114.
4 is a continuous circular slot having a substantially rectangular cross section, but this is only one example. For example, the cross-section can be shaped to progressively expand or contract toward the surface 214 of the pilot burner 114. Further, instead of a single continuous slot, two or more concentric continuous slots may be used. Instead of a continuous slot, a plurality of circles formed on the surface 214 of the pilot burner 114 are arranged at equal intervals. Individual holes may be used. As yet another variation, the slots or equivalent holes project from the surface 214 of the pilot burner 114 to or near a protrusion or flange that serves to "anchor" and stabilize the combustion process. It can also be formed.

The igniter 110 is a pilot burner 114.
Although shown as being located at the center of the pilot burner 114, this is also provided only as an example, and the igniter 110 may be eccentric from the centerline CL of the pilot burner 114 to, for example, the slot 302 or its equivalent. It may be advantageous to place it at the same diameter as the circular array of holes.
This arrangement may reduce the heat transferred from the flame in region 107 to igniter 110.

The above-described arrangement of the invention for injecting pilot fuel and air has the following further advantages. (a) The annular fuel ejection gap below the deflection lip 216 provides coke anti-sticking action. This is because jetting the fuel inward in the radial direction has the effect of avoiding carbon deposition that directly impedes the flow of the fuel. (b) The arrangement of allowing fuel and air to flow through the pilot burner 114 close to the igniter 110 serves to keep the igniter cool by removing heat from the pilot burner. (c) Giving a swirling motion to the air 300 ejected from the slot 302 of the head of the pilot burner is particularly because the swirling direction of the air 300 is the swirl passage 122 of the main burner.
When the direction is opposite to the spiral direction of the air-fuel mixture ejected from, it serves to prevent the flame in the area 107 from actually adhering to the head 214 of the pilot burner. Therefore, the base of the flame is separated from the head 214 of the pilot burner, thus preventing overheating of the igniter 110. An example of a design made in accordance with the present invention was tested and found that when pilot air 300 was given a swirl component in the same direction as the swirl direction of the air-fuel mixture ejected from the main burner, it gave an opposite swirl component. It was found that the flame burns closer to the igniter than when.

For convenience, the attached drawing shows an example of injecting only one kind of fuel (gas fuel), but a two kinds of fuel combustion burner configuration can also be used. For example, in the body of a pilot burner having a larger diameter than the pilot burner 114, extending a liquid fuel supply passage parallel to the gas fuel supply passage and associated therewith a manifold and liquid fuel atomizer to surround the gas fuel injector. Can be placed.

[Brief description of drawings]

FIG. 1 is a so-called “dry, low NO” incorporating the ignition, fuel burner and combustion stabilization device according to the present invention.
FIG. 3 is a schematic side view with a partial cross-section of the distillation end of an “x” lean burn combustor can.

FIG. 2 is an enlarged cross-sectional view of a portion of FIG.

3 is a cross-sectional view similar to FIG. 2 but taken in a different cross-section to show details not shown in FIG. 2;

[Explanation of symbols]

 100: Combustor 102: Combustor can 103: Main combustion chamber 104: Gas fuel injector assembly (burner device) 106: Combustion zone 107: Base area or sub-zone of combustion zone 108: Large area of combustion zone 110: Ignition Device (ignition source) 114: Pilot burner 118: Main burner 120: Fuel introduction main body part 122: Vortex passage 123: Vortexer 126: Pilot fuel supply passage 128: Main fuel supply passage 130: Manifold 136: Fuel injection means 139: Empty Fuel mixture 200: Fuel 141: Prechamber 214: Burner head or rear surface 215: Hole 216: Deflection lip 300: Air column or curtain 302: Circular groove or slot 303: Hollow (annular) divergent column shear layer 306: Perforation (air supply passage) 314: Air channel Le or grooves

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eric Roy Noster UK 237 EB, Nottingham Sheer, Newark, Harvey, High Street, Peer Tree Cottage (No Address) (72) Inventor Simon Mario De Pietro United Kingdom Elnu 1 3 Dx, Lincoln, Newport 183 (72) Inventor Mahmud Koukaby United Kingdom Elnu 2 2 Jayeu, Linkern, Longdale's Road 38

Claims (27)

[Claims] 1. A burner head (21) comprising fuel injection means (215, 216) and air injection means (302).
A burner (114) for a gas turbine combustor having 4), wherein the fuel injection means surrounds the air injection means in a substantially concentric relationship therewith, the air injection means comprising: ,
Burner, characterized in that it is configured to eject a column of air (300) having an annular cross section, the fuel injection means being configured to inject fuel toward it for mixing with the air column. 2. The burner according to claim 1, wherein the air column is shaped to diverge from the burner. 3. A burner as claimed in claim 1 or 2, characterized in that the air injection means comprises means for defining a circular slot in the burner head. 4. The burner according to claim 1, wherein the air injection unit includes a unit for applying a vortex flow component to the air column. 5. The air injection means comprises a circular slot (302) formed in the burner head (214),
It comprises a plurality of supply passages (306) for supplying air to the bottom wall of the slot, which supply passages (30).
0) The burner according to claim 1 or 2, wherein the burner is opened obliquely to the side wall of the slot at the bottom of the slot so as to impart a vortex motion component to the column. 6. The burner according to claim 5, wherein the supply passage opens tangentially to the bottom of the slot. 7. The fuel injection means comprises means (216) defining an annular hole proximate the periphery of the burner head (214) such that the fuel is ejected from the burner through the hole. The burner according to any one of claims 1 to 6, which is made. 8. The fuel injection means includes an annular lip (216) spaced from and covering an outermost peripheral edge of the burner head (214), the fuel being between the burner and the burner head and lip. The burner according to claim 7, wherein the burner is designed to eject through the burner. 9. The fuel injection means further includes a circular array of holes (215) formed in the burner head below the lip (216), the lip extending from the holes. Burner according to claim 8, characterized in that it serves to direct the injected fuel towards the air column in order to mix it. 10. (a) an outer burner head region including said fuel injection means, (b) said air injection means, and an ignition source for igniting air and fuel injected by said burner into said combustion chamber. 2. Having an inner burner head region containing (110).
The burner according to any one of ~ 9. 11. A combustion pre-chamber (141), a main combustion chamber (103), and a combustion pre-chamber having a main cross-sectional area in the order of the combustion gas flow direction. A burner device (104) for use in a lean burn combustor for a gas turbine engine of a type having a cross section that is considerably smaller than that of a combustion chamber, the burner device (104) maintaining diffusion combustion type combustion in the prechamber A pilot burner (114) disposed in the combustor head for the purpose of: (b) injecting a lean fuel-air mixture (139) into the prechamber. Injecting means (136) and the pilot for imparting an inward swirling motion to the air-fuel mixture as it is injected into the prechamber. The main burner comprising a swirler that is disposed radially outwardly in the downstream of the burner (118)
And the main burner has a fuel introduction body portion (120) housed in the combustor head, the body portion comprising a plurality of fuel supply passages for supplying fuel to the fuel injection means. (128, 130, etc.), the swirler is attached to a body portion of the main burner to form a peripheral edge of an uppermost stream portion of the pre-chamber, and the pilot burner is provided in the body portion of the main burner. Burner device characterized by being fitted. 12. The burner device according to claim 11, wherein an ignition source for igniting the air-fuel mixture is contained in the pilot burner. 13. The pilot burner includes fuel injection means and air injection means, the fuel injection means surrounding the air injection means in a substantially concentric relationship therewith, the fuel injection means comprising: 13. The fuel injection device is configured to inject fuel toward the air injection means to generate a fuel-rich air-fuel mixture in the pre-chamber outside the pilot burner. Burner device according to. 14. The air injecting means is configured to inject an air column having an annular cross-section that diverges from the pilot burner into the pre-chamber. The burner device according to one. 15. A pilot burner (114) and a main burner (118) surrounding the pilot burner downstream of the pilot burner and for injecting an air-fuel mixture for combustion in a combustor. A lean burn combustor for a gas turbine engine, comprising: a pilot fuel (200)
And air (300) are separately and simultaneously injected into the combustor to mix in the combustor, the column having an annular cross section surrounding the area (107) adjacent to the pilot burner. Injecting means (302) for injecting into the combustor as a shear layer (303);
Fuel injection means (215, 216) for injecting the pilot fuel toward the shear layer for mixing with air in the column-shaped shear layer, the main burner having a lean fuel concentration. The main air-fuel mixture (139) is configured to be injected into the combustor toward the column-shaped shear layer, and the column-shaped shear layer stabilizes lean-burn combustion in the combustor. A lean-burn combustor characterized by setting a protected combustion zone to increase the degree of combustion. 16. The lean burn type combustor according to claim 15, wherein the columnar shear layer diverges from the pilot burner. 17. The lean burn combustor according to claim 16, wherein the pilot fuel injection means surrounds the air injection means and is substantially concentric with the air injection means. 18. The lean burn combustor according to claim 17, wherein the air injection means of the pilot burner is configured to impart a swirl flow component to the column of air. 19. The lean burn type according to claim 15, wherein the main burner is configured to impart a swirl flow component to the main air-fuel mixture. Combustor. 20. The pilot burner and the main burner are configured so as to respectively impart mutually opposite eddy flow components to the columnar shear layer and the main air-fuel mixture. Claims 15 to 17
The lean burn combustor according to any one of 1. 21. A gas turbine engine combustor (10)
0) is a method for maintaining a lean burn type combustion process over a wide load condition range of the engine, comprising: (a) injecting air (300) into the combustor to produce a fluid in the combustor. Column-shaped shear layer with flow cross section (303)
And (b) injecting pilot fuel substantially uniformly from a region surrounding the column-shaped shear layer to a circular base portion of the shear layer, and burning the pilot fuel by the shear layer. (C) a lean burn type in the combustor at least at start-up of the engine and at full load conditions, in which the pilot air-fuel mixture is mixed with the air in the shear layer and mixed with the air in the shear layer. A fuel-lean main air-fuel mixture (139) for maintaining a combustion process is injected substantially uniformly from a region surrounding the columnar shear layer downstream of the pilot fuel injection region toward the shear layer. And mixing the main air-fuel mixture with the pilot air-fuel mixture in the shear layer, and (d) being protected by being surrounded by the shear layer near the circular base portion of the shear layer. And the neighboring area in the shear layer And recirculating a portion (304) of the air-fuel mixture (139) from the shear layer into a protected area (107) having a significantly slower flow velocity than the neighboring area ahead of the shear layer; e) Combusting the recycled air-fuel mixture in the protection area to set a protected combustion area, and stabilizing the recycled air-fuel mixture in the protected combustion area. Burning in a controlled manner, thereby stabilizing the overall lean burn type combustion process. 22. The method of claim 21, wherein the columnar shear layer is divergent in the direction of air injection. 23. The method of claim 21 or 22, wherein the columnar shear layer has a rotating vortex flow component of fluid flow about the center of its annular cross section. 24. The fuel-lean main air-fuel mixture has a rotary vortex flow component of a fluid flow around a center of an annular cross section of the column-shaped shear layer.
The method according to any one of 3 above. 25. The column-shaped shear layer and the fuel-lean main air-fuel mixture are rotational vortex flow components of fluid flows in mutually opposite directions around a center (CL) of an annular cross section of the column-shaped shear layer. 23. The method according to claim 21 or 22, characterized by comprising: 26. The relative amounts of air, pilot fuel and main fuel injected into the combustion chamber are burned by the air-fuel mixture in the protected combustion zone at engine start-up and under partial load conditions. 26. A method according to any one of claims 21 to 25, characterized in that the two are modified such that they have sufficient fuel concentrations to maintain stable combustion throughout the process. 27. As the operating conditions of the engine change from start to partial load to full load, the amount of pilot fuel injected as part of the total injected fuel is reduced from a small percentage at start to full speed / minimum. The overall combustion process in the combustor is changed from combustion in a fuel-rich state to combustion in a fuel-lean state by changing from a high rate at a limited load to a 0% rate at full speed / full load. 27. The method of claim 26, wherein the method comprises: