JP2004085123A - Combustor for gas turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustor for a gas turbine capable of securing positive ignition startability and stability of a firm premixed flame, operating in a wide operating range with low NOx and high combustion efficiency (low CO / low HC) and realizing this easily at a low cost. <P>SOLUTION: The combustor 10 is provided with a swirling apparatus 36 at the outlet of a swirling air current passage 38 to apply swirling speed to supplied air. Fuel is injected toward a combustion chamber 16 from a diffusion fuel injection nozzle 28, and fuel for a premixture is injected into a premixing passage 22 from a premixed fuel injection nozzle 24. The premixture formed in the premixing passage 22 is supplied to the combustion chamber 16. At this time, the swirling air current is further blasted toward the combustion chamber 16 by the swirling apparatus 36. A diffusion flame formed at a center region in the combustion chamber 16 by the diffusion fuel injection nozzle 28, and a premixed flame formed at the outer peripheral region, can be turbulently mixed by the swirling air current. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas turbine combustor for burning gaseous fuel or liquid fuel.
[0002]
[Prior art]
2. Description of the Related Art A combustor for a gas turbine that burns a gaseous fuel or a liquid fuel is known. Here, in such a combustor, in recent years, emission of nitrogen oxides (NOx) and unburned fuels such as carbon monoxide (CO) and hydrocarbons (HC) generated during combustion have been reduced due to environmental considerations. It is a big problem.
[0003]
In this type of combustor, diffusion combustion for obtaining stable combustion is usually used. However, in such diffusion combustion, since the adiabatic flame temperature reaches about 2000 ° C., carbon monoxide (CO 2) ) And hydrocarbons (HC), the emission of unburned fuel is relatively small, but there is a disadvantage that a large amount of so-called "thermal NOx" is generated in which nitrogen in the air is oxidized by the high temperature.
[0004]
On the other hand, it is known that this “thermal NOx” can be reduced by lowering the flame temperature. Instead of the conventional diffusion combustion, lean premixed combustion is adopted, and the fuel and combustion air are premixed to reduce the fuel. Means of suppressing the generation of NOx by making a lean gas mixture and burning it at a relatively low temperature have already been attempted.
[0005]
However, in the premixed combustion, for example, when a lean premixed gas having an equivalent ratio of about 0.5 is used, not only the emission of unburned fuel such as carbon monoxide (CO) and hydrocarbon (HC) increases, but also the combustion stability range is reduced. There is a problem that it becomes difficult to reliably start ignition and stable gas turbine operation.
[0006]
Therefore, three fuel supply systems are constituted by the ignition gas ejection holes and the primary and secondary combustion premixed gas ejection holes provided therearound, and the fuel supply control of these three systems is performed. There have been proposed techniques for reducing the NOx by preventing the equivalence ratio of the premixed gas from becoming too lean under relatively wide operating conditions (for example, Patent Documents 1 and 2).
[0007]
However, in the case of a combustor having a large number of fuel supply systems as disclosed in the patent document, there is a merit that the space equivalent ratio in the combustion chamber can be controlled and controlled to an ideal equivalent ratio distribution. However, the device configuration becomes complicated and the fuel control becomes complicated, and the problems remain in the reliability and cost of the component devices.
[0008]
Therefore, the present applicant has already proposed a gas turbine combustor in which the fuel supply system of the combustor is composed of two systems and the fuel supply control of the two systems performs lean premix combustion (Japanese Patent Application No. 2001-394615). ).
[0009]
However, in the combustor of the proposed structure, although the structure is simple and inexpensive, it is still an improvement in ensuring the ignitability and securing the stability of the lean premixed flame under a wide range of operating conditions. There was room.
[0010]
In the combustor having the proposed structure, the fuel injection nozzle faces the space of the combustion air passage or the combustion chamber. Problems such as lack of durability, adhesion of carbon, or poor mixing of the injected fuel and air due to an increase in the viscosity of the heated air may occur.
[0011]
In particular, for example, in a regenerative micro gas turbine in which the thermal efficiency of a simple cycle gas turbine has been improved, the air at the compressor outlet is heated by a heat exchanger for exhaust heat recovery of exhaust gas from the turbine outlet, and is heated to, for example, about 600 ° C. or more. The fuel injection nozzle incorporated in the premixed combustor is always exposed to air at 600 ° C or higher and is also heated by combustion heat from the combustion chamber. become. For this reason, it is necessary to improve the thermal durability of the fuel injection nozzle or to take measures and devices for preventing carbonization of fuel and adhesion of deposits.
[0012]
Furthermore, the air heated at about 600 ° C. or higher heated by the heat exchanger for exhaust heat recovery has a viscosity three times as large as the air at the compressor outlet (eg, about 200 ° C.), and the mixing of the heated air and the fuel is difficult. It gets worse relatively. For this reason, it is difficult to form a uniform lean premixed gas in a limited space in the passage, and a device is required to obtain a sufficiently uniform premixed gas with the same spatial dimensions as in the past. On the other hand, while the heated air may suppress the emission of unburned hydrocarbons (HC) and carbon monoxide (CO), "thermal NOx" Emissions are more likely to be encouraged. In reality, for example, in the case of a micro gas turbine used for a distributed power source, it is required to reduce NOx and CO / HC to less than 10 ppm simultaneously.
[0013]
In this case, it is conceivable to cool the fuel injection nozzle of the premixed combustor with the compressor outlet air at about 200 ° C., but simply using the air for cooling adversely affects the lean premixed flame or diffusion flame. It is difficult to secure both ignition startability and flame stability while simultaneously reducing NOx and CO / HC and improving durability.
[0014]
[Patent Document 1]
JP-A-5-340273
[Patent Document 2]
JP-A-8-128636
[0015]
[Problems to be solved by the invention]
The present invention has been devised for the above contradictory problems, and can ensure a reliable ignition startability and a stable stability of a premixed flame, as well as a low NOx and a wide operating range (operating conditions). An object of the present invention is to provide a gas turbine combustor that can be operated with high combustion efficiency (low CO and low HC) and that can be realized simply and at low cost.
[0016]
[Means for Solving the Problems]
The gas turbine combustor according to the first aspect of the present invention is a diffusion fuel injection nozzle located at an axial portion of a combustion chamber and injecting diffusion fuel toward the combustion chamber, and communicating with the combustion chamber. A pre-mixing passage for supplying a pre-mixed gas, a pre-mixed fuel injection nozzle for injecting pre-mixed fuel into the pre-mixed passage, the diffusion fuel injection nozzle, A swirling device disposed between the premixing passages for injecting a swirling airflow toward the combustion chamber.
[0017]
In the gas turbine combustor according to the first aspect, the fuel for diffusion combustion is injected from the diffusion fuel injection nozzle toward the combustion chamber, and the premixed fuel is injected into the premixing passage from the premixed fuel injection nozzle. Fuel is injected, and the premixed gas formed in the premixing passage is supplied to the combustion chamber. Further, at this time, the swirling device jets the swirling airflow toward the combustion chamber. Thus, the diffusion flame formed in the central region in the combustion chamber by the diffusion fuel injection nozzle and the premixed flame formed in the peripheral region thereof can be turbulently mixed by the swirling airflow.
[0018]
Therefore, the combustion of the diffusion flame by the fuel from the diffusion fuel injection nozzle and the premixed flame by the fuel from the premix passage (premix fuel injection nozzle) are promoted, thereby increasing the combustion efficiency and the temperature in the combustion chamber. Can be made relatively uniform. As a result, the emission of "thermal NOx" can be reduced, and the emission of CO and HC can also be kept low.
[0019]
A gas turbine combustor according to a second aspect of the present invention is the gas turbine combustor according to the first aspect, wherein the diffusion fuel passage communicates with the diffusion fuel injection nozzle and supplies fuel to the diffusion fuel injection nozzle. And a swirling airflow passage, which communicates with the swirling device, is provided in an annular shape around the diffusion fuel passage on the axial center side of the premixing passage, and supplies air to the swirling device. The air supplied through the swirling airflow path is provided with a swirling speed by the swirling device and is ejected to form a swirling airflow in the combustion chamber.
[0020]
Generally, the fuel injected from the premix fuel injection nozzle is premixed with the fuel and air within a relatively short space dimension of the premix passage (average transit time, within about 1 msec), and the outlet of the premix passage (combustion chamber) Since there is no spatial distribution in the circumferential direction and the radial direction at the inlet, and since the air flow rate and the fuel flow rate fluctuate with time, it is actually quite difficult to form a uniform premixed gas.
[0021]
In this respect, in the gas turbine combustor according to the second aspect, the swirling air flow passage is provided annularly around the diffusion fuel passage, and the air supplied through the swirling air flow passage is swirled by the swirling device to reduce the swirling speed. The swirling airflow is applied and ejected to form a swirling airflow in the combustion chamber, and the swirling airflow is ejected to the axial center side (inward side) of the premixing passage. The premixed flame formed by the premixed gas flow having the unevenness is extended downstream in the combustion chamber by the swirling airflow formed therein (the premixed flame is spread to the downstream side of the combustion chamber by the swirling airflow) be able to). Therefore, generation of “thermal NOx” in the combustion chamber is suppressed, and low NOx combustion of, for example, 5 ppm or less can be performed.
[0022]
A gas turbine combustor according to a third aspect of the present invention is the gas turbine combustor according to the first or second aspect, wherein the combustor is located between an outlet of the premix passage and the swirl device. And a flame stabilizer having an annular end face provided to face the.
[0023]
When the premixed flame is extended into the combustion chamber by the swirling airflow as described above, the flame starting portion holding the flame becomes unstable, and the probability of blowing out may increase.
[0024]
In this regard, in the gas turbine combustor according to the third aspect, the flame stabilizer is disposed between the outlet of the premix passage and the swirl device, and the annular end face is provided to face the combustion chamber. The vicinity of the end surface forms a water-stop region, and a flame starting portion is formed in an annular shape downstream of the end surface, so that the holding power of the flame starting portion can be enhanced even when the flame is extended.
[0025]
A gas turbine combustor according to a fourth aspect of the present invention is the gas turbine combustor according to any one of the first to third aspects, wherein the diffusion fuel injection nozzle is configured to shift the diffusion fuel from 80 degrees. It is characterized by having a plurality of injection holes for injecting toward the combustion chamber at a sandwiching angle of 100 degrees.
[0026]
In the gas turbine combustor according to the fourth aspect, fuel is injected from the injection hole of the diffusion fuel injection nozzle into the combustion chamber at an angle of 80 to 100 degrees, so that the swirling airflow formed in the combustion chamber is, for example, burned. Assuming that the fuel is swirling at an angle of 45 degrees with respect to the chamber axis, the injected fuel jet and the swirling air flow relatively collide from the side. As a result, the diffusion fuel and the air are quickly mixed, so that the generation of soot due to the shortage of air in the vicinity of the diffusion fuel injection nozzle is suppressed and the combustion is promoted. For this reason, the flame holding power is increased, and as a result, the flame can be held with a small amount of fuel. Therefore, it is possible to burn with low NOx and high combustion efficiency (low CO and low HC). Further, since the equivalence ratio in the region near the end face of the flame stabilizer is relatively lean, it is possible to prevent the problem of the diffusion fuel injection nozzle due to the adhesion of soot.
[0027]
At the start of ignition of the gas turbine, the amount of air supplied is low due to the low rotational speed of the engine.Therefore, the fuel injected from the injection hole of the diffusion fuel injection nozzle must be directly supplied to the tip of the spark plug installed on the side wall of the combustion chamber. Can be reached and the ignition takes place quickly. Thereafter, in a situation where a large amount of air is supplied as the gas turbine accelerates, the fuel injected from the diffusion fuel injection nozzle mixes well with the swirling airflow, so that the diffusion fuel no longer reaches the combustion chamber side wall surface. Therefore, the wall surface of the combustion chamber is not heated and heated, and the durability of the liner of the combustion chamber is improved.
[0028]
A gas turbine combustor according to a fifth aspect of the present invention is the gas turbine combustor according to any one of the first to fourth aspects, wherein a plurality of injection holes of the diffusion fuel injection nozzle are configured to perform the combustion. The swirling device is provided at a position equally spaced on the circumference of the tip of the nozzle facing the chamber, and the swirling device is disposed in the immediate vicinity of the injection hole.
[0029]
In the gas turbine combustor according to the fifth aspect, the injection holes are provided at equal positions on the circumference of the nozzle tip facing the combustion chamber, so that the fuel injected from these injection holes effectively reduces the flame. Since the swirl device can be held and the swirl device is arranged in the immediate vicinity of each injection hole, the dispersion and mixing of the fuel from each injection hole is improved, and low NOx and low CO / low HC combustion can be achieved. .
[0030]
A gas turbine combustor according to a sixth aspect of the present invention is the gas turbine combustor according to any one of the second to fifth aspects, wherein the swirling airflow path is connected to the combustion chamber and the premixing path. The diffusion fuel injection nozzle or the premixed fuel injection nozzle may be provided separately by a partition wall, and may be disposed in the swirling airflow passage.
[0031]
In the gas turbine combustor according to the sixth aspect, since the diffusion fuel injection nozzle or the premixed fuel injection nozzle is disposed in the swirling airflow passage separated from the combustion chamber and the premixed passage by the partition wall, for example, the air heated to 600 ° C. No exposure. For this reason, the diffusion fuel injection nozzle or the premixed fuel injection nozzle itself can be effectively shielded from heat, and problems such as carbonization or deposition of fuel can be prevented.
[0032]
A gas turbine combustor according to a seventh aspect of the present invention is the gas turbine combustor according to any one of the second to sixth aspects, wherein the premixed fuel injection nozzle has a plurality of injection holes. And injecting fuel into the premixing passage and injecting airflow from the periphery thereof into the premixing passage.
[0033]
In the gas turbine combustor according to the seventh aspect, the premixed fuel injection nozzle is constituted by a plurality of injection holes, and furthermore, the fuel flow to the premix passage is effected by jetting an airflow from around each injection hole. The gaseous fuel can be premixed or the liquid fuel can be prevaporized and premixed.
[0034]
According to an eighth aspect of the present invention, in the gas turbine combustor according to any one of the second to seventh aspects, an airflow is supplied directly from a high-pressure source to the swirling airflow passage. It is characterized by:
[0035]
For example, in a regenerative gas turbine in which the exhaust heat of a gas turbine can be recovered to increase the thermal efficiency, the air at the compressor outlet recovers the exhaust heat with a heat exchanger and is heated to, for example, 600 ° C. and supplied to a combustor. Therefore, for example, the injection nozzle for liquid fuel may not have thermal durability, or carbonization or deposition of fuel may be a problem.
[0036]
In this regard, in the gas turbine combustor according to the eighth aspect, even when the gas turbine combustor is applied to a regenerative gas turbine, for example, heat exchange is performed because the gas flow is directly supplied from the high-pressure source to the swirling air flow passage. By supplying the previous compressor outlet air (air having a relatively low temperature: for example, 200 ° C.) to the swirling airflow path and jetting the swirling airflow into the combustion chamber, the air and the fuel can be effectively mixed (low temperature). Air is easier to mix because of its lower viscosity). Therefore, the premixed flame is easily formed uniformly, and the temperature in the combustion chamber can be made substantially uniform.
[0037]
Note that a boiler may be used as the high-pressure source. In this case, the airflow is steam (for example, about 180 ° C.), and the same effect can be expected.
[0038]
Further, since air is supplied to the swirling air flow passage (that is, around the diffusion fuel passage communicating with the diffusion fuel injection nozzle), the diffusion fuel injection nozzle itself can be effectively shielded and cooled, and the fuel carbon can be cooled. This makes it possible to prevent problems such as conversion or deposition. Further, the air cools the diffusion fuel passage, so that it is possible to suppress a rise in the temperature of, for example, the flame stabilizer wall around the diffusion fuel injection nozzle, and prevent burning of the injection nozzle and the flame stabilizer. .
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a sectional view showing the overall configuration of a gas turbine combustor 10 according to a first embodiment of the present invention.
[0040]
The combustor 10 is a so-called can-type combustor including an outer cylinder 12 having a substantially cylindrical shape and an inner cylinder 14 arranged in the outer cylinder 12. The inner cylinder 14 forms a combustion chamber 16. It is a combustion chamber liner. The combustion chamber 16 (the inner cylinder 14) is provided with a dilution hole 18 for introducing air into the interior and diluting the combustion gas.
[0041]
An air inflow path 20 is formed between the outer cylinder 12 and the inner cylinder 14 to allow combustion air compressed by a compressor 56 described later to flow from the end (the right end in FIG. 1) of the outer cylinder 12. Further, a premixing passage 22 is formed continuously in the air inflow passage 20. The premixing passage 22 is formed in an annular shape inside the end of the inner cylinder 14 and communicates with the combustion chamber 16. The premixing passage 22 guides fuel from a premixed fuel injection nozzle 24 described later and air from the air inflow passage 20. The flow is reversed so as to be supplied to the combustion chamber 16. The premixed gas supplied to the combustion chamber 16 from the premix passage 22 is burned in the combustion chamber 16, then flows out from the rear end side (the right end in FIG. 1) of the combustion chamber 16 and is supplied to a turbine 52 described later. It has become.
[0042]
A premix fuel injection nozzle 24 is arranged in the premix passage 22, and a swirler blade 26 is provided further downstream thereof. The premixed fuel injection nozzle 24 is capable of injecting fuel (premixed fuel) into the premixed passage 22, whereby the premixed fuel is mixed with air from the air inflow passage 20 to form a premixed air, and the swirler blades The swirling speed is given to the premixed gas by 26 and supplied to the combustion chamber 16.
[0043]
On the other hand, a diffusion fuel injection nozzle 28 and a diffusion fuel passage 30 communicating with the diffusion fuel injection nozzle 28 are arranged at the axial center of the combustion chamber 16 at one end (the left end in FIG. 1) of the apparatus. As shown in detail in FIGS. 2A to 2C, the diffusion fuel injection nozzle 28 includes a plurality of injection holes 32A and 32B. These injection holes 32A and 32B are respectively provided at equal positions on the circumference of the nozzle tip facing the combustion chamber 16, and are supplied from the diffusion fuel passage 30 from the injection holes 32A and 32B. The fuel (diffused fuel) can be injected into the combustion chamber 16 at a sandwiching angle of 80 to 100 degrees (in the first embodiment, at a sandwiching angle of 90 degrees). Further, the fuel injected from the diffusion fuel injection nozzle 28 is set so as to reach the tip of the ignition plug 34 arranged on the side of the combustion chamber 16.
[0044]
A swirling device 36 and a swirling airflow passage 38 are provided between the diffusion fuel injection nozzle 28 (diffusion fuel passage 30) and the premix passage 22. As shown in detail in FIGS. 2 (A) to 2 (C), the swirl device 36 is located in the immediate vicinity of the injection holes 32A and 32B of the diffusion fuel injection nozzle 28, and is formed by forming a member into a concave groove shape. It is provided so that a turning speed can be given to the supplied air. In this case, the swirling airflow is set to be ejected to the injection holes 32A and 32B at substantially 30 degrees to 45 degrees. On the other hand, the swirl air flow passage 38 is located upstream of the swirl device 36 and communicates with the swirl device 36, and is provided in an annular shape around the diffusion fuel passage 30 on the axial center side of the premix passage 22. . The swirling airflow passage 38 is connected to a compressor 56 described later, and is configured to supply air. Thereby, the air supplied through the swirling air flow passage 38 is given a swirling speed by the swirling device 36 and directed toward the combustion chamber 16 in a direction intersecting with the fuel injected into the combustion chamber 16 from the injection holes 32A and 32B. The fuel is ejected to form a swirling airflow in the combustion chamber 16 and is configured to collide with the fuel.
[0045]
Further, a flame stabilizer 40 is provided between the outlet of the premixing passage 22 and the swirl device 36 (around the tip of the diffusion fuel injection nozzle 28 and the swirl device 36). The flame stabilizer 40 has an annular end face 42 provided facing the combustion chamber 16, and has a role of forming a water blocking area and forming an annular flame starting portion downstream of the end face 42. Have.
[0046]
As shown in FIG. 3, the combustor 10 having the above-described configuration is applied to, for example, a regenerative micro gas turbine 50 that can recover exhaust heat of a turbine 52 and increase thermal efficiency.
[0047]
That is, in this regenerative micro gas turbine 50, the exhaust gas at the outlet of the turbine 52 is configured to be supplied to the heat exchanger for exhaust heat recovery 54, and the air at the outlet of the compressor 56 is used as the heat for exhaust heat recovery. After being sent to the exchanger 54 and heated (for example, at about 600 ° C. or higher), it is supplied to the air inlet 20 of the combustor 10. Further, a part of the outlet air of the compressor 56, that is, a part of the outlet air of the compressor 56 before the heat exchange (air having a relatively low temperature: for example, 200 ° C.) is transferred to the exhaust heat recovery heat exchanger 54. It is configured to be directly supplied to the swirling air flow passage 38 of the combustor 10 without being supplied.
[0048]
Next, the operation of the first embodiment will be described.
[0049]
When the regenerative micro gas turbine 50 to which the combustor 10 having the above configuration is applied is started, fuel is injected from the diffusion fuel injection nozzle 28 of the combustor 10 into the combustion chamber 16 and the combustion speed is still low. The flow rate of the working air is very small, and the fuel reaches the tip of the spark plug 34 on the side wall of the combustion chamber 16 with little influence of the swirling airflow.
[0050]
Then, when spark ignition is performed, the flame nucleus formed at the tip of the spark plug 34 spreads in the combustion chamber 16 and reaches the recirculation region near the flame stabilizer 40 so that the flame is held. During this time, the rotation speed of the gas turbine increases, the flow rate of combustion air increases, and a swirling airflow is also formed. Therefore, the fuel is no longer mixed with the swirling airflow before reaching the tip of the spark plug 34 to complete combustion. I will do it.
[0051]
Further, when the rotation speed of the gas turbine increases and the load region where the turbine 52 generates an output is reached, the fuel is injected from the premixed fuel injection nozzle 24 and the fuel from the diffusion fuel injection nozzle 28 is reduced, so that almost the entire fuel is reduced. Only a small flow rate of 1/10 to 1/20 or less of the supply amount is directly injected from the diffusion fuel injection nozzle 28 to form a pilot flame in the combustion chamber 16. Further, for example, in a high-load operation of 50% load or more, the fuel injection from the diffusion fuel injection nozzle 28 is stopped, all the fuel is injected from the premixed fuel injection nozzle 24, and the operation is performed with complete premixed combustion. .
[0052]
Here, in the combustor 10 according to the first embodiment, as described above, the fuel for diffusion combustion is injected from the diffusion fuel injection nozzle 28 toward the combustion chamber 16 and the premixed fuel injection nozzle 24 The fuel for the premixed gas is injected into the premixing passage 22 from the premixing passage 22, and the premixed gas formed in the premixing passage 22 is supplied to the combustion chamber 16. Further, at this time, the swirling airflow is jetted toward the combustion chamber 16 by the swirling device 36. Accordingly, the diffusion flame formed in the central region in the combustion chamber 16 by the diffusion fuel injection nozzle 28 and the premixed flame formed in the peripheral region thereof can be turbulently mixed by the swirling airflow.
[0053]
Therefore, the combustion of the diffusion flame by the fuel from the diffusion fuel injection nozzle 28 and the premixed flame by the fuel from the premix passage 22 (the premix fuel injection nozzle 24) are promoted. The spatial distribution of the temperature in the combustion chamber 16 can be made relatively uniform. As a result, the emission of "thermal NOx" can be reduced, and the emission of CO and HC can also be kept low.
[0054]
Further, generally, the fuel injected from the premixed fuel injection nozzle 24 is premixed with the fuel and air within a relatively short space dimension of the premix passage 22, and the outlet of the premix passage 22 (the inlet of the combustion chamber 16). In practice, it is practically very difficult to form a premixed gas that has no spatial distribution in the circumferential direction and the radial direction and that is uniform in time.
[0055]
In this regard, the present combustor 10 includes a swirling airflow passage 38 provided annularly around the diffusion fuel passage 30, and the air supplied through the swirling airflow passage 38 is given a swirling speed by the swirling device 36. To form a swirling airflow in the combustion chamber 16, and since the swirling airflow is formed to be ejected to the axial center side (inward side) of the premixing passage 22, the swirling airflow is present at the outlet of the premixing passage 22, The premixed flame formed by the premixed gas stream having a non-uniform concentration is extended downstream in the combustion chamber 16 by the swirling airflow formed inside the premixed flame (the premixed flame is swept by the swirling airflow into the combustion chamber 16). Can be extended to near the right center). Therefore, generation of “thermal NOx” in the combustion chamber 16 is suppressed, and low NOx combustion of, for example, 5 ppm or less can be performed.
[0056]
Further, when the premixed flame is extended into the combustion chamber 16 by the swirling airflow as described above, the flame starting portion holding the flame becomes unstable, and the probability of blowing out may increase.
[0057]
In this regard, in the present combustor 10, the flame stabilizer 40 is disposed between the outlet of the premixing passage 22 and the swirl device 36, and the annular end face 42 is provided so as to face the combustion chamber 16. The vicinity of 42 forms a water stopping area, and a flame starting portion is formed in an annular shape downstream of the end surface 42. Even when the flame is extended, the holding power of the flame starting portion can be enhanced.
[0058]
Further, in the combustor 10, the fuel is injected from the injection holes 32A and 32B of the diffusion fuel injection nozzle 28 at an angle of 80 to 100 degrees (in the first embodiment, at an angle of 90 degrees). Since the swirling airflow formed in the combustion chamber 16 is swirling at an angle of, for example, 45 degrees with respect to the axis of the combustion chamber 16, the injected fuel jet and the swirling airflow are relatively injected. The vehicle is in a positional relationship of colliding almost from the side. As a result, the diffusion fuel and the air are quickly mixed, so that the generation of soot due to the shortage of air in the vicinity of the diffusion fuel injection nozzle 28 is suppressed, and the combustion is promoted. For this reason, the flame holding power is increased, and as a result, the flame can be held with a small amount of fuel. Therefore, it is possible to burn with low NOx and high combustion efficiency (low CO and low HC). In addition, it is possible to prevent the problem of the diffusion fuel injection nozzle due to the adhesion of soot.
[0059]
Here, FIG. 4 is a diagram comparing the effects of the injection angle (sandwich angle) of the diffusion fuel injected from the diffusion fuel injection nozzle 28 (the plurality of injection holes 32A and 32B) toward the combustion chamber 16 on the combustion efficiency. It is shown. As is apparent from FIG. 4, the fuel is injected into the combustion chamber 16 at an angle of 80 or 90 degrees as compared with the case where the fuel is injected into the combustion chamber 16 at an angle of 45 or 60 degrees, for example. If so, it can be seen that the combustion efficiency is greatly improved.
[0060]
When the ignition of the gas turbine 50 is started, the amount of air supplied is small. Therefore, the fuel injected from the injection holes 32A and 32B of the diffusion fuel injection nozzle 28 can be directly and reliably supplied to the tip of the ignition plug 34 installed on the side wall of the combustion chamber 16. Can be reached and the ignition takes place quickly. Thereafter, in a situation where a large amount of air is supplied as the gas turbine 50 accelerates, the fuel injected from the diffusion fuel injection nozzle 28 is sufficiently mixed with the swirling airflow, so that the diffusion fuel is no longer in the combustion chamber 16 side. It does not reach the wall surface, so that the wall surface of the combustion chamber 16 is not heated and heated, and the durability of the combustion chamber 16 (combustion chamber liner) is improved.
[0061]
Further, in the present combustor 10, the injection holes 32A and 32B are provided at equal positions on the circumference of the nozzle tip facing the combustion chamber 16, so that the fuel ejected from these injection holes 32A and 32B causes a flame. And the swirl device 36 is disposed in the immediate vicinity of each of the injection holes 32A, 32B, so that the dispersion and mixing of the fuel from each of the injection holes 32A, 32B is improved, and the NOx is reduced. In addition, low CO and low HC combustion can be performed.
[0062]
Further, here, as in the first embodiment, for example, in the regenerative micro gas turbine 50 that can improve the thermal efficiency by recovering the exhaust heat of the turbine 52, the air at the outlet of the compressor 56 uses the waste heat recovery. Since the exhaust heat is recovered by the heat exchanger 54 for heating and heated to, for example, 600 ° C. and supplied to the combustor 10, for example, the injection nozzle for liquid fuel has no thermal durability, or carbonization or deposition of fuel is performed. Can be a problem.
[0063]
In this regard, even when the present combustor 10 is applied to the regenerative micro gas turbine 50, since the air is directly supplied from the compressor 56 (high-pressure air source) to the swirling air passage 38, the heat is By supplying the outlet air of the compressor 56 before replacement (air having a relatively low temperature: for example, 200 ° C.) to the swirling air flow passage 38 and injecting the swirling air flow into the combustion chamber 16, the air and fuel are effectively mixed. Yes (air with lower temperature is easier to mix due to lower viscosity). Therefore, the premixed flame is easily formed uniformly, and the temperature in the combustion chamber 16 can be made substantially uniform.
[0064]
In addition, since air is supplied to the swirling air flow passage 38 (that is, around the diffusion fuel passage 30 communicating with the diffusion fuel injection nozzle 28), the diffusion fuel injection nozzle 28 itself can be effectively shielded from heat and cooled. In addition, problems such as carbonization or depositing of fuel can be prevented. Further, the air cools the diffusion fuel passage 30, so that the temperature rise around the diffusion fuel injection nozzle 28, for example, on the wall surface of the flame stabilizer 40 can be suppressed, and burning of the flame stabilizer 40 can be prevented. You can also.
[0065]
Here, according to the result of observation of the diffusion combustion flame during the operation of the combustor 10 by the present applicant, the fuel injected from the diffusion fuel injection nozzle 28 (the central part of the flame stabilizer 40) has a flame near the injection. Is not formed (there is no flame in the central region of the combustion chamber 16), and a ring-shaped flame is formed on the annular end surface 42 of the flame stabilizer 40 provided inside the premix passage 22. It has been found. In the conventional combustor, it has been found that a bell-shaped (or tulip-shaped) flame column is formed from the end face 42 of the flame stabilizer 40 in the central region of the combustion chamber 16 as yellowish. On the other hand, in the combustor 10 according to the first embodiment, there is no yellow flame, and a hollow blue flame formed in the outer peripheral region is formed, which indicates that the combustion is good. This is because air is ejected from the swirling airflow passage 38 near the end face 42 of the flame stabilizer 40 as a swirling airflow having an inclination of about 45 degrees, so that the air is ejected from the injection holes 32A and 32B at a sandwiching angle of 90 degrees and radially emitted. This is because the swirling airflow collides with the spread fuel from substantially the lateral direction and the mixing is promoted in a short time, and the combustion is completed in a relatively short space. In other words, in the conventional combustor, a solid bell-shaped flame is formed, and the downstream portion of the combustion chamber 16 is narrowed down. Therefore, the inside of the flame column is rich in fuel and rich in soot generation. In the present combustor 10, by promoting the mixing with the swirling airflow spouting from the end face 42 (the swirling airflow passage 38) of the flame stabilizer 40, the flame starting portion is formed in a ring shape on the end face 42 of the flame stabilizer 40. The flame surface is expanded and formed into a hollow skirt, and the length of the diffusion flame is reduced. As a result, the gas temperature at the inlet of the turbine 52 becomes uniform both spatially and temporally, the factors contributing to temporal fluctuations in the engine speed are reduced, the fluctuations in fuel control are reduced, and the flame stability is further improved. The property becomes good.
[0066]
Further, when observing the complete premixed combustion in which all the fuel is injected only from the premixed fuel injection nozzle 24, the conventional combustor supplies combustion air exceeding 600 ° C. from the premixed passage 22 to the combustion chamber. Further, since the high-temperature gas in the recirculation region in the combustion chamber 16 collides with the end face 42 of the flame stabilizer 40 from the downstream side, the diffusion fuel injection nozzle 28 and the flame stabilizer 40 themselves are red-heated. On the other hand, in the present combustor 10, the relatively low temperature (about 200 ° C.) air at the outlet of the compressor 56 is supplied through the swirling air passage 38 to cool the flame stabilizer 40 itself. The swirling airflow spouting from the swirling device 36 is prevented from quickly mixing with the high-temperature gas in the recirculation region to heat the wall surface. At this time, the premixed flame forms a ring-shaped flame starting portion on the annular end face 42 of the flame stabilizer 40 provided between the swirling device 36 and the outlet of the premixing passage 22, and the stability of the flame is impaired. Not. Further, in the conventional combustor, the brightness of the premixed flame has shading. On the other hand, in the present combustor 10, the swirling airflow stretches the inside of the combustion chamber 16 from the inside of the combustion chamber 16 by the shearing airflow to promote the mixing. Is not observed and forms a uniform bright blue flame. As a result, the exhausted NOx concentration is halved to about 5 ppm in the present combustor 10 from about 10 ppm (converted value of oxygen 16%) in the conventional combustor.
[0067]
Further, in the conventional combustor, the end face 42 of the flame stabilizer 40 has a large heat rise, so that the combustor 10 is not particularly durable when there is frequent up-down operation. However, in the present combustor 10, the temperature rise is suppressed. Therefore, durability is improved.
[0068]
As described above, the combustor 10 according to the first embodiment can ensure reliable ignition startability and strong premixed flame stability, as well as low NOx and high combustion in a wide operating range (operating condition). It can be operated with high efficiency (low CO and low HC), and can be realized simply and at low cost.
[0069]
Next, a second embodiment of the present invention will be described.
[0070]
Note that components that are basically the same as those in the first embodiment are given the same reference numerals as in the first embodiment, and descriptions thereof are omitted.
[0071]
FIG. 5 is a cross-sectional view showing the overall configuration of a gas turbine combustor 60 according to a second embodiment of the present invention.
[0072]
The combustor 60 is configured to perform premixing of gaseous fuel or pre-evaporation of liquid fuel to perform lean combustion, and a pre-evaporation pre-mixed fuel injection nozzle 62 is disposed in the swirling air passage 38. . The pre-evaporated pre-mixed fuel injection nozzle 62 has a plurality of injection holes, and is disposed to face a through-hole 66 formed in a partition wall 64 on the upstream side of the pre-mixing passage 22 (downstream of the swirler blade 26). Have been. Thus, the pre-evaporated pre-mixed fuel injection nozzle 62 is configured to be able to eject the pre-evaporated pre-mixed fuel together with the air into the pre-mix passage 22 through the through hole 66.
[0073]
On the other hand, the diffusion fuel injection nozzle 68 disposed at the center of the combustor is disposed to face the through hole 72 formed in the end face partition wall 70 of the flame stabilizer 40, and further, around the diffusion fuel injection nozzle 68 An annular turning device 74 is arranged. As shown in detail in FIGS. 6 (A) and 6 (B), the swirling device 74 is located around the diffusion fuel injection nozzle 68 and is provided by forming a member in a concave groove shape. It is configured so that the swirling speed can be given to the air that has been blown. Further, as shown in FIG. 7, a plurality of air holes 76 are formed around the through hole 72 in the end wall 70 of the flame stabilizer 40. As a result, the air supplied through the swirling airflow passage 38 is given a swirling speed by the swirling device 74, and the sprayed fuel injected from the diffusion fuel injection nozzle 68 and the swirling airflow are combined together with the through-hole 72 and the air hole. In this configuration, the fuel can be injected into the combustion chamber 16 via the valve 76.
[0074]
In this case as well, each air hole 76 is provided at an even position on the circumference of the end wall 70 of the flame stabilizer 40 facing the combustion chamber 16, and is further injected from the through hole 72. Can be injected into the combustion chamber 16 at an angle of 80 to 100 degrees (in the second embodiment, at an angle of 80 degrees), and the injected fuel is It is set so as to reach the tip of the spark plug 34 arranged on the side of the combustion chamber 16.
[0075]
In the combustor 60 having the above-described configuration, the pre-evaporated pre-mixed fuel injection nozzle 62 is disposed in the swirling airflow passage 38 separated from the pre-mixing passage 22 by the partition 64, and is burned by the flame stabilizer 40 (the end wall 70 thereof). Since the diffusion fuel injection nozzles 68 are arranged separately from the chamber 16, these injection nozzles are not exposed to air heated to, for example, 600 ° C. For this reason, the diffusion fuel injection nozzle 68 or the pre-evaporation pre-mixed fuel injection nozzle 62 itself can be effectively shielded from heat, and problems such as carbonization or deposition of fuel can be prevented. Further, the diffusion fuel injection nozzle 68 and the pre-evaporated premixed fuel injection nozzle 62 are cooled by the relatively low-temperature (about 200 ° C.) air supplied to the swirling air flow passage 38 and the swirling air flow is formed and injected. In addition, the radiation from the spray flame formed in the combustion chamber 16 can be reduced, whereby the heat rise can be suppressed, and the clogging of the fuel and the problem of deposit adhesion can be more reliably avoided.
[0076]
Further, in this combustor 60, the pre-evaporated pre-mixed fuel injection nozzle 62 is composed of a plurality of injection holes, and furthermore, the air in the swirling air flow passage 38 is discharged around each of the injection holes of the pre-evaporation pre-mixed fuel injection nozzle 62. Of the fuel in the premix passage 22 and mixing with the air is facilitated (the fuel is effectively dispersed in the premix passage 22). Gas fuel can be effectively premixed, or liquid fuel can be effectively pre-evaporated premixed.
[0077]
Further, the spray fuel and the swirling airflow injected from the diffusion fuel injection nozzle 68 are injected together into the combustion chamber 16 through the through hole 72 and the air hole 76, or are injected from the pre-evaporation premix fuel injection nozzle 62. Since the sprayed fuel is ejected to the premixing passage 22 through the through hole 66 together with the air, the atomization of the liquid fuel is also promoted, and the dispersion and mixing of the fuel are more quickly and uniformly performed.
[0078]
【The invention's effect】
As described above, the gas turbine combustor according to the present invention can ensure reliable ignition startability and robust premixed flame stability, and can achieve low NOx and high combustion efficiency (low combustion efficiency) over a wide operating range (operating conditions). (CO / low HC), and has an excellent effect that this can be realized simply and at low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an entire configuration of a combustor according to a first embodiment of the present invention.
FIGS. 2A and 2B show details of a diffusion fuel injection nozzle and a swirl device of a combustor according to a first embodiment of the present invention, wherein FIG. 2A is a side view, FIG. 2B is a front view, and FIG. () Is a sectional view.
FIG. 3 is a schematic block diagram illustrating an entire configuration of a regenerative micro gas turbine to which the combustor according to the first embodiment of the present invention is applied.
FIG. 4 is a diagram comparing the effects of the injection angle (sandwich angle) of the diffusion fuel injected from the diffusion fuel injection nozzle toward the combustion chamber on the combustion efficiency in the combustor according to the first embodiment of the present invention. is there.
FIG. 5 is a cross-sectional view illustrating an entire configuration of a combustor according to a second embodiment of the present invention.
FIG. 6 shows details of a swirl device of a combustor according to a second embodiment of the present invention, where (A) is a side view and (B) is a front view.
FIG. 7 is a front view showing details of a through hole and a plurality of air holes provided in a flame stabilizer of a combustor according to a second embodiment of the present invention.
[Explanation of symbols]
10 Combustor
16 Combustion chamber
20 Air inflow path
22 Premix passage
24 Premix fuel injection nozzle
26 swirler feather
28 Diffusion fuel injection nozzle
30 Diffusion fuel passage
32A orifice
32B orifice
34 spark plug
36 Swivel device
38 Swirling airflow passage
40 flame stabilizer
42 end face

Claims (8)

A diffusion fuel injection nozzle that is located at the axial center of the combustion chamber and injects diffusion fuel toward the combustion chamber;
A premixing passage that is provided in an annular shape around the diffusion fuel injection nozzle in communication with the combustion chamber and that supplies a premixed air;
A premix fuel injection nozzle that injects premix fuel into the premix passage,
A swirling device disposed between the diffusion fuel injection nozzle and the premix passage, for injecting a swirling airflow toward the combustion chamber;
A combustor for a gas turbine, comprising: A diffusion fuel passage communicating with the diffusion fuel injection nozzle and supplying fuel to the diffusion fuel injection nozzle;
A swirling airflow passage that communicates with the swirling device, is provided in an annular shape around the diffusion fuel passage on the axial center side of the premixing passage, and supplies air to the swirling device;
Wherein the air supplied through the swirling airflow path is given a swirling speed by the swirling device and ejects to form a swirling airflow in the combustion chamber.
The gas turbine combustor according to claim 1, wherein: The flame stabilizer having an annular end face provided between the outlet of the premixing passage and the swirl device and facing the combustion chamber is provided. 3. The gas turbine combustor according to 2. The diffusion fuel injection nozzle has a plurality of injection holes for injecting the diffusion fuel toward the combustion chamber at an angle of 80 to 100 degrees.
The gas turbine combustor according to any one of claims 1 to 3, wherein: The plurality of injection holes of the diffusion fuel injection nozzle are provided at equally spaced positions on a circumference of a nozzle tip facing the combustion chamber, and the swirl device is disposed immediately adjacent to the injection hole.
The combustor for a gas turbine according to any one of claims 1 to 4, wherein: The swirling airflow passage is provided separately from the combustion chamber and the premixing passage by a partition, and the diffusion fuel injection nozzle or the premixed fuel injection nozzle is disposed at the swirling airflow passage.
The gas turbine combustor according to any one of claims 2 to 5, wherein: 7. The premix fuel injection nozzle has a plurality of injection holes, injects fuel into the premix passage, and discharges an airflow from the periphery to the premix passage. The gas turbine combustor according to any one of claims 1 to 4. The gas turbine combustor according to any one of claims 2 to 7, wherein an airflow is supplied directly to the swirling airflow path from a high-pressure source.

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