Patent Grant
6871503
The present invention relates to a premixer for gas turbine combustors, a premixing method for gas turbine combustors, a gas turbine combustor and a combustion method for gas turbine.
In a gas turbine combustor and a combustion method for gas turbines, in order to reduce exhaust amount of NOx which is an air pollution material, an application of premixing combustion method is now progressing in which fuel and air premixed before the fuel is introduced into a combustion chamber. For example, as disclosed in JP-A-3-175211 (1991), a diffusive combustion showing excellent stability is assigned at the center portion of the combustion chamber and a premixing combustion showing excellent low NOx property is assigned at the outer circumferential side thereof, thereby, NOx reduction is achieved. In this disclosure, air sent from a compressor passes between a combustor outer cylinder and a combustor liner and flows in respectively such as a combustion chamber and a pre-mixer.
Diffusive combustion use fuel is injected from a diffusion fuel nozzle into the combustion chamber to form stable diffusive flame and premixing use fuel is injected from a premixing fuel nozzle into an annular premixer to mix air and to from premixed gas.
The above premixed gas flows out into the combustion chamber to form premixing flame. The generated high temperature combustion gas is introduced into a turbine to perform works and thereafter is exhausted.
In a low NOx combustor making use of such premixing combustion, formation of uniform premixed gas greatly affects the low NOx performance. In particular, in the above conventional example which is structured in such a manner that the air flow makes a U turn at the inlet of the premixer, a drift with regard to air flow is likely caused which makes difficult to form a uniform mixing gas. Namely, for such measure it requires great attention of advancing the mixing in the premixer.
With regard to air flow in such premixer, JP-A-60-223578 (1985) and JP-A-2-267419 (1990), for example, disclose technical measures therefor.
JP-A-2-267419 (1990) discloses such a technique that a partition wall is provided for every nozzles so as to separate the same in the circumferential direction in the premixer, inlet windows of which opening is deviated are provided so that premixing combustion use air flows in an deviated manner, thereby a swirl component is caused in the premixing combustion use air and the mixing with fuel is advanced. However, the disclosure does not fully takes into account the relationship between the window configuration and the fuel nozzles.
An object of the present invention is to provide a premixer for gas turbine combustor, a premixing method for gas turbine combustors, a gas turbine combustor and a combustion method for gas turbines which uniformalize the premixing and show an excellent low NOx performance.
A gas turbine combustor according to the present invention comprising diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame, outer and inner walls which from an annular premixing flow passage and premixing nozzles which are disposed in the premixing flow passage and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber, is characterized in that a plurality of the premixing nozzles are arranged in the premixing flow passage; opening portions permitting air to flow in are provided at the outer wall so that the air flowed into the premixing flow passage forms swirling flow with respect to the premixing nozzles; and the opening portions are disposed in circumferential direction and are provided one for every adjacent two premixing nozzles.
A gas turbine combustor according to another aspect of the present invention comprising diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame, outer and inner walls which form an annular premixing flow passage and a premixing nozzles which are disposed in the premixing flow passage and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber, is characterized in that a plurality of the premixing nozzles are arranged in the premixing flow passage; opening portions permitting air to flow in are provided at the outer wall so that the air flowed into the premixing flow passage forms swirling flow with respect to the premixing nozzles; and the opening portions are disposed in circumferential direction and are provided one for every adjacent two premixing nozzles and the rotating directions of the swirling flows for the respective two premixing nozzles are caused to direct opposite direction each other.
A gas turbine combustor according to still another aspect of the present invention comprises: diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame; an inner cylinder arranged outside the diffusive combustion nozzles; a plurality of premixing nozzles which are arranged outside the inner cylinder circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber; and means for forming respective swirling flows of different rotating direction for the adjacent two premixing nozzles in circumferential direction.
A gas turbine combustor according to a further aspect of the present invention comprising diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame, outer and inner walls which form an annular premixing flow passage and premixing nozzles which are disposed in the premixing flow passages and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber, is characterized in that a plurality of the premixing nozzles are arranged in the premixing flow passage; and opening portions permitting air to flow in are provided at the outer wall so that the air flowed into the premixing flow passage forms swirling flows for the adjacent two premixing nozzles.
A gas turbine combustor according to a still further aspect of the present invention comprising diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame, outer and inner walls which form an annular premixing flow passage and premixing nozzles which are disposed in the premixing flow passage and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber, is characterized in that a plurality of the premixing nozzles are arranged in the premixing flow passage; opening portions permitting air to flow in into the premixing flow passage are provided at the outer wall and at portions between adjacent two premixing nozzles in the circumferential direction; and isolation wall members which are provided respectively at both sides of the adjacent two premixing nozzles in the circumferential direction.
A gas turbine combustor according to a still further aspect of the present invention comprises: diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame; an inner cylinder arranged outside the diffusive combustion nozzles; a plurality of premixing nozzles arranged outside the inner cylinder in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber; means for forming respective swirling flows of different rotating direction for the adjacent two premixing nozzles in circumferential direction; and a member which surrounds the adjacent two premixing nozzles in the circumferential direction along the axial direction thereof.
A gas turbine combustor according to a still further aspect of the present invention comprising diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame, outer and inner walls which form an annular premixing flow passage and premixing nozzles which are disposed in the premixing flow passage and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber, is characterized in that a plurality of the premixing nozzles are arranged in the premixing flow passage; and opening portions permitting air to flow in are provided at the outer wall so that the air flowed into the premixing flow passage forms swirling flows with respect to the premixing nozzles, thereby, the rotating directions of the swirling flows for the respective two premixing nozzles are caused to direct opposite directions each other.
A gas turbine combustor according to a still further aspect of the present invention comprises diffusive combustion nozzles which inject fuel and air into a combustion chamber and form a diffusive combustion flame, outer and inner walls which form an annular premixing flow passage and premixing nozzles which are disposed in the premixing flow passage and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into the combustion chamber, wherein a plurality of the premixing nozzles are arranged in the premixing flow passage; opening portions permitting air to flow in are provided at the outer wall so that the air flowed into the premixing flow passage forms swirling flow with respect to the premixing nozzles; and each of the opening portions is configured in nearly a triangular shape in such a manner either that the opening broadens in the main air stream direction prior to flowing into the premixer or that the opening decreases in the main air stream direction prior to flowing into the premixer; and the rotating directions of the swirling flows for the respective two premixing nozzles are caused to direct opposite directions each other.
A gas turbine combustor use premixing device according to one aspect of the present invention comprising a plurality of premixing nozzles which are arranged in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into a combustion chamber, is characterized in that one air flow inlet for every adjacent two premixing nozzles is provided so that a swirling flow is formed for the respective adjacent two premixing nozzles in the circumferential direction.
A gas turbine combustor use premixing device according to another aspect of the present invention comprising a plurality of premixing nozzles which are arranged in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into a combustion chamber, is characterized in that one air flow inlet for every adjacent two premixing nozzles is provided so that swirling flows of which rotating directions are opposite each other are formed for the respective adjacent two premixing nozzles in the circumferential direction.
A gas turbine combustor use premixing device according to still another aspect of the present invention comprising a plurality of premixing nozzles which are arranged in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into a combustion chamber, is characterized in that means is provided which forms swirling flows of which rotating directions are different for the respective adjacent two premixing nozzles in the circumferential direction.
A premixing method for a gas turbine combustor according to one aspect of the present invention comprising a plurality of premixing nozzles which are arranged in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into a combustion chamber, is characterized in that air is flown from air flow inlets each being provided for every adjacent two premixing nozzles in the circumferential direction, and swirling flows are formed around the respective adjacent two premixing nozzles.
A premixing method for a gas turbine combustor according to another aspect of the present invention comprising a plurality of premixing nozzles which are arranged in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into a combustion chamber, is characterized in that air is flown from air flow inlets each being provided for every adjacent two premixing nozzles, and swirling flows of which rotating directions are opposite each other are formed around the respective adjacent two premixing nozzles.
A premixing method for a gas turbine combustor according to still another aspect of the present invention comprising a plurality of premixing nozzles which are arranged in circumferential direction and form a premixing combustion flame by injecting premixed gas formed by premixing fuel and air into a combustion chamber, is characterized in that one air flow inlet for every adjacent two premixing nozzles is provided so that swirling flows of which rotating directions are different each other are formed around the respective adjacent two premixing nozzles in the circumferential direction.
Hereinbelow, embodiments of the present invention will be explained.
In the embodiments of the present invention, a measure is taken that an inlet window is configured in such a manner that the width in circumferential direction of the inlet window varies along the axial direction of a combustor and thereby, such as strength and size of swirls can be controlled so as to obtain the maximum effect.
Further, for the fuel nozzles arranged along the circumferential direction in a premixer one inlet window is assigned for two pieces of the fuel nozzles to form one set so that each set thereof causes to generate a pair of two swirls, thereby number of inlet windows is relatively reduced as well as partition walls in the premixer is also reduced which prevent attenuation of the swirls and further advances the mixing.
Through the reduction of the inlet windows and the partition walls in the premixer the manufacturing cost thereof can be reduced as well as through strengthening and optimizing the swirl further highly uniform premixing gas can be obtained and a combustor showing an excellent low NOx performance can be provided.
(Embodiment 1)
Hereinbelow, a first embodiment of the present invention will be explained with reference to FIG. 1 through FIG. 6.
As shown in
Further, diffusive combustion use fuel 16 is injected into the combustion chamber 1 from diffusion fuel nozzles 13 to from a stable diffusive flame 4. Premixing use fuel 21 is injected from premixing fuel nozzles 8 into an annular shaped premixer 12 to form premixed gas 22 by mixing with air. The premixed gas 22 flows out into the combustor 1 to form a premixing flame 5. Then, the generated high temperature combustion gas is introduced into a turbine 18 to perform work and thereafter exhausted.
In a low NOx combustor making use of such premixing combustion, formation of uniform premixed gas greatly affects the low NOx performance. In particular, in the above conventional example which is structured in such a manner that the air flow makes a U turn at the inlet of the premixer, a drift with regard to air flow is likely caused which makes difficult to form a uniform mixing gas. Namely, for such measure it requires great attention of advancing the mixing in the premixer.
A partial vertical view of a combustor to which the present invention is applied is shown in
The combustor outer cylinder 2 is for preventing the high temperature and high pressure air 50 from leaking to the outer atmosphere and for securing combustor members to a gas turbine main body. The combustor liner 3 forms the combustor 1, and of which inner portion combustion reaction between fuel and air is performed to generate high temperature combustion gas and which introduces the high temperature combustion gas to the turbine.
The premixer 12 forms an annular passage, forms the premixed gas 22 in the passage by mixing the fuel and air, flows out the same into the combustor 1, and causes to perform premixing combustion with limited amount of NOx exhaustion.
The air passage 203 is an annular passage for passing the high temperature and high pressure air to the premixer 12.
A plurality of premixing fuel nozzles 8 are arranged in the annular passage near the inlet of the premixer 12 along the circumferential direction thereof so as to properly distribute the fuel, and each of the fuel nozzles 8 is provided with not less than one fuel injection port 81 through which fuel is injected into the premixer 12.
The partitions 31 serving as isolation walls mechanically support the inner and outer circumferential walls of the premixer 12 as well as partition the annular passage of the premixer 12 into a plurality of chambers in circumferential direction thereof.
Now, the present invention will be explained with reference to FIG. 1 through FIG. 3.
In the present embodiment, an air inlet opening portions 30 serving as an air inlet windows form inlet ports through which air flows in from the air passage 203 to the premixer 12, the opening portions are distributedly arranged along the circumferential direction in a rate of for every one opening portion two pieces of fuel nozzles 8 and each of the main opening area is arranged so as to locate at the intermediate position in circumferential direction of the two pieces of fuel nozzles.
The width of the opening portion is configured to gradually decrease in the main air flow direction flowing through the air passage 203, thereby, the opening portions are configured a planform trapezoid shape.
Now, an operation of the embodiment of the present invention will be explained. As shown in
As shown in
In the combustor 1, premixing flame is formed by making use of the high temperature gas in the diffusive combustor at the upstream side as an ignition source or by making use of a proper flame holder (such as a bluff body), and a premixing combustion reaction with limited NOx generation is performed to generate high temperature combustion gas.
Herein, the higher the uniformity of the fuel density in the premixed gas 21, the more the uniformity of temperature of the combustion gas is achieved, thereby a low NOx combustion can be realized while eliminating a high temperature portion which operates as NOx generation source.
Now, processes of mixing fuel and air in the present embodiment will be explained in detail with reference to FIG. 7 through FIG. 24.
At first, configuration of the air inlet window and air flow caused in the premixer will be explained with reference to FIG. 7 through FIG. 12.
As shown in FIG. 7 through
On the other hand, as shown in FIG. 10 through
Now, with reference to
The embodiment as shown in
Further,
The embodiment as shown in
In a case when the configuration of the air inlet window is not varied in the flow direction which corresponds to the example as shown in
As has been explained above, through distribution of the premixer air inlet windows 30 in circumferential direction and formation in the premixer of a pair of vortexes of which swirling directions are opposing each other, the mixing between fuel and air in the premixer can be advanced.
Further, through configuring the air inlet opening portions 30 serving as the premixer air inlet window nearly a triangular shape in such a manner the width thereof gradually decreases in the flow direction of the air 50, the size and strength of the vortexes 301 can be increased, thereby, the agitating and mixing action thereof is further strengthened.
Now, a relationship between position of the air inlet window 30 and premixing fuel nozzles 18 and mixing process will be explained with reference to
In
On the other hand,
In the present embodiment, for each of the premixing inlet air windows since a pair of vortexes of which swirling directions are opposing are formed, the swirling directions of the vortexes for adjacent premixer inlet air windows are also directing oppositely each other, thereby, interference therebetween hardly occurs. Therefore, different from the conventional structure which necessitates partitions 31 serving as the isolation walls partitioning the premixer flow passage for every window along the circumferential direction, however, in the present embodiment it is sufficient if the minimum number of isolation walls is provided which maintains mechanical strength required for the premixer. Namely, the partition can be omitted to take an easy structure or the partitions 31 can be simplified. Generally, a major cause of attenuation of the vortexes 301 which advance the mixing is an attenuation due to friction loss with the premixer walls, with the premixer inlet air windows according to the present embodiment the attenuation of the formed vortexes can be extremely limited, thereby, further uniform premixed gas can be formed.
To put this differently, the length of the premixer necessary for obtaining the premixed gas having the same uniformity can be shortened and effect of cost reduction and freedom for designing can be enhanced.
Further, the unstable break away vortexes in the circumferential direction are hardly formed which possibly contributes to reduce negative potentials such as back fire.
At the same time, as in the present embodiment, the number of isolation walls can be minimized, which also contributes manufacturing cost reduction.
(Embodiment 2)
A second embodiment of the present invention will be explained with reference to FIG. 25. Although the basic structure of the present invention is the same as that of the first embodiment, a different point thereof is that the width of the air inlet opening portions 30 is kept unchanged in the main flow direction of air. Through thus constituting, although the agitating and mixing performance thereof somewhat reduces as has been explained above, easiness of parts manufacturing and assembling the same can be enhanced.
(Embodiment 3)
A third embodiment of the present invention will be explained with reference to FIG. 26. Although the basic structure of the present invention is the same as that of the first embodiment, a different point thereof is that the air inlet opening portions 30 are configured into nearly a triangular shape in such a manner that the width thereof is broadened in the main flow direction of the air. Through thus constituting, the swirling vortex generation sources at the downstream side of the windows are limited in a narrow range in comparison with other embodiments as has been explained above and comparatively gentle mixing can be realized and the present embodiment is effective in a case where the mixing degree at the inner circumferential side is required to be gentle in view of interference with the diffusive combustion at the upstream side.
Now, comparison result of swirling intensity of vortexes with regard to the above embodiments 1 through 3 will be explained with reference to FIG. 30.
These swirling intensities are higher than conventional ones and the attenuation of the swirling intensity in the axial direction is low in comparison with conventional ones.
Among these, it is observed that the swirling intensity of the embodiment 1 is generally high. Namely, in the case of nearly triangular shaped opening portion wherein the width thereof gradually decreases in the main air flow direction, it is observed that the swirling intensity thereof is extremely high.
Further, with regard to the embodiments 1 through 3, comparison on attenuation of the vortex swirling intensities will be explained with reference to FIG. 31.
Among the embodiments 1 through 3, the swirling intensity of embodiment 1 is generally high and when comparing with the embodiment 2, even if the axial direction distance is prolonged, it is observed that the swirling intensity is hardly attenuated. Namely, in the case of nearly triangular shaped opening portion wherein the width thereof gradually decreases in the main air flow direction (directing in opposite direction from the premixed gas flow direction), it is observed that the swirling intensity thereof is hardly reduced.
As has been explained above, with the present embodiment the attenuation of vortexes formed by the premixer inlet air windows can be minimized and further uniform mixed gas can be formed, thereby, the present embodiment contributes to enhance low NOx performance. The length of the premixer necessary for obtaining the premixed gas having the same uniformity can be shortened and effect of cost reduction and freedom for designing can be enhanced. Further, the unstable break away vortexes in the circumferential direction are hardly formed which possibly contributes to reduce negative potentials such as back fire. At the same time, as in the present embodiment, the number of isolation walls can be minimized, which also contributes to manufacturing cost reduction.
(Embodiment 4)
A fourth embodiment of the present invention will be explained with reference to
(Embodiment 5)
The premixing device includes the combustor outer cylinder 2, the cylindrical shaped combustor liner 3 and a plurality of premixing fuel nozzles 8 including the flow passages leading to the combustion chamber 1 and disposed in each of the premixer passages in the circumferential direction thereof.
The combustor outer cylinder 2 is for preventing the high temperature and high pressure air 50 from leaking to the outer atmosphere and for securing combustor members to a gas turbine main body. The combustor liner 3 forms the combustor 1, and of which inner portion combustion reaction between fuel and air is performed to generate high temperature combustion gas and which introduces the high temperature combustion gas to the turbine. In the premixer 12 a part of the air 14 and 50 sent in the main flow direction flows into the premixer flow passage as the premixing air and, in the passage premixed gas 22 is formed by mixing the fuel and air to flow out the same into the combustor 1, and thereby to cause to perform premixing combustion with limited amount of NOx exhaustion. Further, the air 14, the other part of the air 50, is sent to the diffusion side.
A plurality of sets of premixing fuel nozzles 8, each set includes a plurality of premixing fuel nozzles 8, are arranged in the passage near the inlet of the premixer 12 along the circumferential direction thereof so as to properly distribute the fuel. The flow passages are formed for every set so as to surround the respective sets. In the present embodiment, as shown in
In the present embodiment as shown in
(Embodiment 6)
Namely, for the respective adjacent two premixing fuel nozzles 8 a corresponding inlet window is formed and the opening area of the respective inlet windows is gradually reduced toward outside near from the centers of the respective premixing fuel nozzles 8. Further, each of the opening portion areas is gradually reduced in the main stream direction. With this structure, the swirling directions formed around the adjacent two premixing fuel nozzles 8 are directed in opposite directions each other and a swirling flow having high swirling intensity can be formed.
Further, when put this differently, a nearly triangular shaped inlet portion of which opening portion area is gradually decreased toward the main stream direction is provided for every adjacent two premixing fuel nozzles 8, thereby, an interrupting portion which prevents air flow is formed near the center of the nearly rectangular shaped inlet portion. Through thus constituting, the swirling directions formed around the adjacent two premixing fuel nozzles 8 are directed in opposite directions each other and a swirling flow having high swirling intensity can be formed.
Further, the gradually reducing opening portion area toward the main stream direction of the nearly rectangular shaped inlet portion can be formed in a curved shape as shown in FIG. 39.
According to the present invention a premixer for gas turbine combustors, a premixing method for gas turbine combustors, a gas turbine combustor and a combustion method for gas turbines which uniformalize the premixing and show an excellent low NOx performance can be provided.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCTJP99/05779 | 10/20/1999 | WO | 00 | 7/18/2002 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO0129484 | 4/26/2001 | WO | A |
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