JPH0743137B2 - Gas turbine combustor - Google Patents

Description

The present invention relates to a gas turbine combustor, and more specifically, a catalyst for suppressing the generation of nitrogen oxide (NOx) which is a pollution source of the environment. The present invention relates to a gas turbine combustor designed to be used together.

(Prior Art) In recent years, various alternative energies have been demanded with the depletion of petroleum resources and the like, but at the same time, efficient use of energy resources has been demanded. Among those that meet these requirements are, for example, a gas turbine / steam turbine combined cycle power generation system that uses natural gas as a fuel, or a coal gasification gas turbine / steam turbine combined cycle power generation system, which is currently under study.

These gas turbine / steam turbine combined cycle power generation systems have higher power generation efficiency than conventional steam turbine power generation systems that use fossil fuels, so natural gas, coal gas, etc., whose production is expected to increase in the future, are expected. It is expected as a power generation system that can effectively convert the fuel of the above to electric power.

In a gas turbine combustor used in such a gas turbine power generation system, a mixed gas of a fuel and an oxidizing gas (generally referred to as air, hereinafter referred to as air) has been conventionally ignited by using a spark plug or the like to obtain a uniform gas. Burning. FIG. 8 shows an example of a conventional gas turbine combustor. In this gas turbine combustor, the fuel F injected from the fuel nozzle ₁ is mixed with the combustion air A ₁ pressure-fed from the air duct 3 and ignited by the spark plug 5 to burn. Then, the burned gas, that is, the combustion gas, after the cooling air A ₂ and the dilution air A ₃ are added to cool and dilute to a predetermined turbine inlet temperature,
It is injected from the turbine nozzle 7 into the gas turbine. 9
Is a swirler.

One of the serious problems in such a conventional gas turbine combustor is that a large amount of NOx is generated at the time of combustion of fuel, which adversely affects environmental pollution. And this NO
The reason why x is generated is that at the time of combustion of the fuel, there is a high-temperature part partially exceeding 2000 ° C. in the combustor.

In order to solve the problems of such a gas turbine combustor, various combustion methods have been studied, and recently, a catalytic combustion method using a solid-phase catalyst has been proposed. This catalytic combustion method uses a catalyst to burn a lean fuel that cannot be burned by an ordinary combustor. Therefore, the combustion temperature does not become high enough to generate NOx. Further, the turbine inlet temperature can be the same as the conventional one.

FIG. 9 is an example of a combustor used in the catalytic combustion system.
Among the reference numerals in the figure, the same elements as those shown in FIG. 8 represent the same elements. This combustor is structurally characterized in that it has a sub-nozzle 11 and a catalyst 13 on the gas flow path. The catalyst body 13 is usually loaded with a honeycomb structure combustion catalyst, and a mixed gas of fuel and air is burned therein.

However, such a gas turbine combustor also has the following problems. In other words, the temperature of the combustion gas injected into the turbine required for the gas turbine is approximately 1100 ° C (it will be even higher in the future with the aim of improving efficiency),
When the gas mixture is burned to that temperature by the catalyst body, the catalyst body itself is heated to a temperature higher than 1100 ° C. and the catalyst body is damaged. The experiments conducted by the inventors of the present invention have also confirmed that the temperature of the catalyst body 13 rises to 1100-1300 ° C. Despite such circumstances, there is currently no catalyst body that has excellent durability at high temperatures of 1100 to 1300 ° C.

Therefore, the present inventors have previously proposed a catalytic combustion method in which gas phase combustion in the downstream of the catalyst body 13 is effectively used to reduce the heat load of the catalyst body 13 (Japanese Patent Application No. 58-229967). . In this method, as shown in FIG. 10, first, fuel F ₁ and air A ₁ , A ₂
This is a method of burning a lean mixed gas of and with the catalyst 13.
Usually, when an oxidation reaction of a flame-retardant lean air-fuel mixture is carried out using a catalyst body, catalytic combustion (catalytic combustion) by reaction on the catalyst surface and gas phase combustion in the honeycomb structure and the like occur at the same time, In the above proposal, the fuel concentration, temperature, flow rate, etc. of the mixed gas are controlled so that only catalytic combustion occurs. Therefore, since no high temperature combustion occurs in the catalytic body, the temperature does not rise, and only part of the fuel burns, and the combustion gas containing unburned fuel is discharged from the catalytic body 13. This prevents the catalyst body from being damaged by heat.

In the above proposal, for the exhausted combustion gas,
Furthermore, by adding new fuel from a fuel supply pipe 15 provided downstream of the catalyst body 13 shown in FIG. 10, the fuel concentration in the gas is increased to cause gas phase combustion downstream of the catalyst body 13, This made it possible to raise the temperature of the combustion gas supplied to the gas turbine. That is, NOx usually shows the maximum generation amount near the theoretical mixing ratio of fuel and air,
In this proposal, by performing gas-phase combustion downstream of the catalyst body 13 on the lean mixing ratio side, the required combustion gas temperature can be obtained by achieving complete combustion of fuel while suppressing NOx generation. Is.

(Problems to be Solved by the Invention) However, the vapor phase combustion downstream of the catalyst body in the above proposal has the following problems. That is, the fuel concentration distribution is non-uniform due to the addition of a high concentration of unmixed air from the fuel supply pipe 15 to the flow of the combustion gas discharged from the catalyst body 13. That is, the catalyst body
Downstream of 13, there are partially high and low fuel concentrations. As a result, in places where the fuel concentration is partially high, the combustion temperature must be high,
Therefore, NOx is generated.

In order to solve such a problem, a fuel supply unit that makes the fuel concentration distribution uniform on the downstream side of the catalyst body 13 is desired. As such a fuel supply unit, there are a method of supplying fuel from the inside of the combustor and a method of ejecting fuel from the combustor shell wall 17 into the combustor.

It is easier to supply the fuel from the inside of the combustor to obtain a uniform fuel concentration distribution, but it is necessary to cool the fuel supply part because it is exposed to high temperature gas. However, due to the complexity of the structure and the reliability of the fuel supply unit at high temperatures, the above problems have not been solved yet.

On the other hand, the method of ejecting from the combustor shell wall 17 into the combustor is
Although there are few problems in heat resistance of the fuel supply section, it is necessary to obtain a predetermined fuel penetration distance in order to obtain uniform fuel concentration distribution. The fuel penetration distance largely depends on the fuel pressure. However, when the combustor becomes large, there is a problem that the fuel penetration distance cannot be sufficiently obtained at the prescribed fuel pressure.

The present invention has been made in view of the above-mentioned conventional problems, and the fuel can be sufficiently uniformly mixed with the combustion gas in the downstream of the catalyst body, and is damaged by exposing the catalyst body to a high temperature. It is an object of the present invention to provide a gas turbine combustor that is capable of suppressing the generation of NOx without causing any problems in terms of hardware.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, a gas turbine combustor according to the present invention includes a supply unit for a mixed gas containing an oxidizing gas and a lean fuel, and this supply unit. In a gas turbine combustor having a catalyst body for catalytic combustion installed downstream of the gas turbine and a gas phase combustor downstream of the catalyst body for generating combustion gas to a gas turbine. At the base end side, there is provided a divided flow passage structure for dividing the gas passing through the catalyst body into a plurality of flows, and the divided flow passage constitution body is provided with fuel supply means for supplying fuel to each of the divided flow passages. At least one of the upstream end and the downstream end of the passage structure is formed with a space portion that surrounds the divided flow passage, and a cooling air introduction passage that communicates with this space portion and a divided flow passage that also communicates with the space portion are formed. The discharge passage and the divided flow passage structure are provided. It is.

(Operation) In the gas turbine combustor according to the present invention, the fuel-lean mixed gas from the mixed gas supply portion is catalytically burned in the catalyst body and flows into the divided passages as combustion gas. Then, in this divided flow path, fuel is added from the fuel supply means for each flow path, mixed with the combustion gas, sent out to the gas phase combustion section, and gas phase combustion is performed there. Therefore, the catalytic combustion portion only catalytically burns at a relatively low temperature, and complete combustion is achieved in the downstream gas-phase combustion portion.

Moreover, the fuel supply means is provided in the divided flow path structure,
Since the fuel is injected into each of the divided flow paths, it is easy to make the fuel concentration distribution uniform, and it is possible to realize gas-phase combustion with less NOx generation.

In order to be established as a combustor, the combustibility as well as the reliability of the constituent members are required. In the combustor of this structure, the divided flow passage structure is exposed to the hot gas after catalytic combustion, but the cooling air flows into the space of the divided flow passage structure through the cooling air introduction passage, As a result, the end of the divided flow path structure is cooled, and then flows out to the divided flow path side through the discharge passage. For this reason, since the end portion of the divided flow path structure that is particularly exposed to high temperature is cooled, the heat resistance and durability thereof are improved.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows the overall construction of this embodiment, and the portions common to the conventional example shown in FIGS. 8 to 10 are designated by the same reference numerals.

The mixed gas supply unit 20 includes a fuel nozzle 1, a spark plug 5, a swirler 9, a sub nozzle 11, and the like, respectively. Then, the fuel F supplied from the fuel nozzle 1 is mixed with the combustion air A ₁ and ignited by the spark plug 5 to pre-combust. In this case, the swirler 9 stirs fuel and air to stabilize combustion, but pre-combustion is not always necessary depending on the type of fuel and catalyst used. The fuel gas pre-combusted in this manner is replenished with the fuel F ₁ from the sub nozzle 11 and the air A ₂ from the air duct 3 to generate a mixed gas, which is supplied to the catalyst body 13. In this case, the working temperature of the catalyst body 13 is stably maintained, and in order to generate a lean air-fuel mixture having an appropriate temperature such that the temperature is not high enough to cause damage,
Fuel F ₁ and air A ₂ together with the temperature and amount of the above pre-combustion gas
The amount of replenishment with is adjusted.

A gas-phase combustion section 21 is formed on the downstream side of the catalyst body 13,
A divided flow channel structure 25 is provided on the base side thereof. As shown in FIG. 2, a plurality of divided flow passages 25, in this example, seven divided flow passages 27, and the divided flow passages 27 are contained in the divided flow passages 27.
A fuel supply means 35 for separately supplying the fuel F ₂ into the inside, and a cooling means 51 for mainly cooling both end faces of the divided flow path constituting body 25 are integrally provided.

More specifically with reference to FIG. 3 and FIG.
27 is formed by partition walls 29, 31 fixed at the base end of the gas-phase combustion section 21 so as to face each other, and a short circular pipe 33 hung over and welded to these partition walls 29, 31. There is. Further, the fuel supply means 35 is provided with a fuel distribution chamber 39 formed inside a hollow disk-shaped jacket 37 surrounding these seven circular tubes 33.
And a fuel feed pipe 41 joined to the jacket 37 and a nozzle hole communicating from the fuel distribution chamber 39 to the divided flow passage 27 through the circular pipe 33.
43 and. An appropriate number of nozzle holes 43 are arranged in each divided channel 27 in equal angular relationship. Fuel supply pipe 41
The fuel F ₂ delivered from the fuel tank is a fuel gas alone or a mixture of fuel gas and air, and the divided flow passage 27 and the nozzle holes are provided.
The number and diameter of 43 are set according to basic conditions such as the flow rate and properties of the gas flowing through the catalyst body 13 and the fuel pressure and flow rate of the fuel F ₂ . At this time, it is desirable that the penetration distance of the fuel F ₂ from the nozzle hole 43 be equal to or larger than the radius of the divided passage 27, and this condition can be easily satisfied because the passage is divided and the passage diameter is small. it can.

Further, in order to uniformly supply the fuel F ₂ to each of the divided flow passages 27 through each of the plurality of nozzle holes 43, a region where the fuel gas is hard to flow between the circular pipes 33, a so-called dead space is generated as much as possible. It is necessary to prevent this, and for that purpose, it is possible to take measures such as adjusting the disposition position of the divided passage 27 or changing the cross-sectional shape. Further, in order to effectively mix the mixed gas having passed through the catalyst body 13 and the fuel from the nozzle hole 43, it is preferable to provide these nozzle holes as close to the catalyst body 13 as possible.

Next, the basic structure of the cooling means 51 is that air A ₄ is introduced from the transparent window 53 provided in the air duct 3 between the partition walls 29 and 31 to cool the divided flow passage structure 25 and then to introduce it into the divided flow passage 27. It is the one. In this case, the dead spaces of air are formed near the partition walls 29 and 31, and as a result, these partition walls are heated by receiving the radiant heat from the catalyst body 13 and the vapor phase combustion section 21, respectively. Therefore, in this embodiment, the disks 55 and 57 are joined to the insides of the partition walls 29 and 31, respectively, to form a double structure, thereby forming the air distribution chambers 59 and 61 as the space portions inside them. . Then, the air A ₄ taken in through the transparent window 53 is supplied to each disk 55, 5
Through-holes 63 and 65 formed in 7 as many cooling air introduction passages
After being made to flow into the air distribution chambers 59, 61 from the air supply chambers 59, 61, each circular pipe 33 is supplied to each divided flow passage 27 through a proper number of air nozzle holes 67, 69 which are opened in an equiangular relationship. There is.

The operation of the gas turbine combustor having the above structure will be described below.

The fuel F supplied from the fuel supply nozzle 1 is mixed with the combustion air A ₁ , ignited by the spark plug 5 and pre-combusted, and mixed with the fuel F ₁ supplied from the sub nozzle 11.
It becomes a mixed gas and flows into the catalyst body 13.

In the catalyst body 13, the mixed gas causes a catalytic reaction and catalytically burns. In this catalytic combustion, the temperature rise of the catalyst body 13 is suppressed by adjusting the fuel flow rate supplied from the sub nozzle 11. This catalytic combustion becomes incomplete combustion and the catalytic body
Combustion gas discharged from 13 contains unburned fuel,
It does not matter since it is completely combusted in the gas phase combustion part of the subsequent flow. Since the catalyst body 13 does not reach such a high temperature, its deterioration and damage are less likely to occur. The combustion gas discharged from the catalyst body 13 is mixed with the new fuel gas F ₂ supplied in the divided flow path 27 to become a mixed gas and is sent to the gas phase combustion unit 21. Then, in this divided flow channel structure 25, the air A ₄ flows into the air distribution chambers 59, 61 sequentially through the through holes 63, 65 while cooling the flow channel wall from outside by contacting the circular pipe 33, After cooling the partition walls 29, 31 with the air nozzle holes 67, 69
Flow out while being distributed to each of the divided flow paths 27 via the, and these participate in the combustion air. And again the air nozzle hole 67
Since the air flowing out from the film performs a film cooling action while advancing along the flow path wall of the divided flow path 27, this flow path wall is also cooled from the inside, and the heat resistance problem of the divided flow path structure 25 is not a problem. Will be resolved.

Further, in the portion of the divided flow path 27, new fuel F ₂ is mixed with the combustion gas from the catalyst body 13 in a narrow region in order to obtain a predetermined combustion temperature, so that the gas-phase combustion section 21 downstream thereof is provided. The fuel concentration of the mixed gas that enters is made uniform, and the generation of NOx can be suppressed more effectively.

In the gas-phase combustion unit 21, since the lean air-fuel mixture is originally burned, if the cooling air is too much, the combustibility is deteriorated. Therefore, this amount of air is preferably suppressed to an extent necessary for cooling. For example, forming a heat-resistant and heat-insulating layer such as a ceramic coating layer on the flow path wall helps to suppress the amount of cooling air. Further, the upstream side temperature and the downstream side temperature of the divided flow channel constituting body 25 cannot be said to be lower depending on the working temperature of the catalyst body 13, but the partition wall 29 or 31 on the low temperature side may be provided with the heat resistant heat insulating layer if necessary. Air distribution chamber 59
Alternatively, 61 can be omitted.

Here, the circular pipe 33 forming each divided flow path 27 is accompanied by thermal expansion, but by providing the bellows 34 in each flow path as shown in FIG. 5, the thermal expansion can be absorbed. Therefore, even if there is a temperature distribution in the cross section of the combustor and there is a difference in the thermal expansion of each divided flow passage 27, the divided flow passage constituent body 25 will not be deformed, and the reliability in terms of hardware will be great. .

In the gas-phase combustion section 21, for example, an expanded diameter section that delays or reverses the flow of gas as shown in FIG.
When 19 is formed on the shell wall 17, the gas flow circulates inside the expanded diameter portion 19 and a flame holding portion is formed there, so that gas phase combustion is stably performed.

Further, if an ignition source 23 such as an igniter is provided in a region downstream of the divided flow channel structure 25, for example, as shown in FIG. 7, vapor phase combustion can be easily started, which is effective.

(Experimental Example of the Invention) A gas turbine combustor having a structure as shown in FIG. 1 was manufactured and its combustion characteristics were investigated. The diameter of the flow path in the catalyst body area here is 30
0 mm, the diameter of each of the divided channels 27 is 81 mm, and the number of divided channels is 7
I thought The cooling structure of the divided flow paths was a double structure in which the air distribution chambers 59 and 61 were provided inside the partition walls 29 and 31, and the bellows 34 was provided to absorb the thermal expansion of each flow path. The amount of cooling air that flows into the divided flow path portion is equal to the catalyst inlet air amount of 2
The opening areas of the air nozzle holes 67 and 69 were set so as to be%. A noble metal honeycomb having a diameter of 300 mm and a length of 150 mm was used as the catalyst body.

In the supply unit 20, the mixed gas in which the natural gas (F ₁ ) and the air A ₂ ) are mixed in the volume ratio (F ₁ / A ₂ ) shown in the following table is heated up to 450 ° C by pre-combustion and then heated to 500 ° C. Combustion was carried out by supplying the catalyst at a flow rate of 30 m / sec based on actual equipment.

It should be noted that the nozzle hole 43 is provided in each divided flow path 27 through the fuel supply pipe 41.
Natural gas (F ₁ +) including natural gas (F ₂ ) supplied from
The ratio (F ₁ + F ₂ ) / A of F ₂ ) to air (A ₂ + A ₄ = A) is set as shown in the following table, and the ignition of gas phase combustion is performed by the igniter.
I went more.

Then, the NOx generation amount (ppm) in the exhaust gas generated by combustion was measured at a position 700 mm downstream of the catalyst body. The combustion efficiency was 99% or higher in all cases.

As a comparative example, a gas turbine combustor having the structure shown in FIG. 10 was used to perform combustion under the same conditions as in the example. In addition, 28 fuel supply pipes 15 are provided downstream of the catalyst body,
The fuel supplied from this fuel supply pipe was designated as F ₂ .

The metal temperature of the divided channels according to this example was 700 ° C. or lower. For comparison, when a combustion test was performed using a divided flow passage not provided with a cooling means, the characteristics of the exhaust gas were not much different from those of this example, but the metal temperature of the divided flow passage was 80%.
The temperature could be as high as 0 ° C or higher. Further, when the divided flow passage was inspected after several tests, cracks were found in a part of the divided flow passage where no cooling means was provided.

[Advantages of the Invention] As described above, according to the present invention, the divided flow passages are formed on the downstream side of the catalyst body, and the fuel supply means is provided in the divided flow passage constituents forming each divided flow passage. Since the combustion gas from the catalyst and the fuel supplied to the divided flow channel are mixed in a narrow area, the fuel concentration distribution can be made uniform in each part, and the NOx generation amount is effectively suppressed. can do. Furthermore, since a space is formed at either one of the upstream side and the downstream side of the divided flow channel structure and cooling air is introduced into this space, it is made to flow out to the divided flow channel side, so that it is exposed to particularly high temperatures. The temperature of the above-mentioned end portion is prevented from becoming high, and the reliability in terms of hardware becomes great.

[Brief description of drawings]

FIG. 1 is a side cross-sectional explanatory view of a combustor according to an embodiment of the present invention, FIG. 2 is a perspective view of the divided flow channel structure of FIG. 1, and FIG.
FIG. 4 is a side sectional view of FIG. 2, FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3, and FIG. 5 is a side sectional view of a split channel structure according to another embodiment. FIG. 7 is a side sectional explanatory view of a combustor according to another embodiment of the present invention, and FIGS. 8, 9 and 10 are side sectional explanatory views of a combustor according to a conventional example. 13 …… Catalyst body, 20 …… Mixed gas supply section 21 …… Gas phase combustion section, 25 …… Split channel structure 27 …… Split channel, 35 …… Fuel supply means 51 …… Cooling means 59, 61 …… Air distribution chamber (space) 63, 65 …… Through hole (cooling air introduction passage) 67,69 …… Air nozzle hole (exhaust passage)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Terunobu Hayata 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Research Institute Ltd. Inside the Technical Research Laboratory, Kyoden Electric Co., Ltd. (72) Noriyoshi Hara, 2-4-1 Nishitsujigaoka, Chofu-shi, Tokyo Inside the Technical Research Laboratory, Tokyo Electric Power Co., Inc. Tokyo Electric Power Company Technical Research Center

Claims (1)

[Claims] 1. A supply unit for a mixed gas containing an oxidizing gas and a lean fuel component, a catalytic combustion catalyst body installed downstream of the supply unit, and a gas turbine located downstream of the catalytic body. In a gas turbine combustor having a gas-phase combustor for generating combustion gas, a divided flow path structure is provided on the base end side of the gas-phase combustor for dividing the gas passing through the catalyst into a plurality of flows. A fuel supply means for supplying fuel to each of the divided flow passages is provided in the divided flow passage structure, and a space portion surrounding the divided flow passage is formed at at least one of an upstream end and a downstream end of the divided flow passage structure. The gas turbine combustor is characterized in that a cooling air introduction passage communicating with the space portion and a discharge passage to the division passage communicating with the space portion are provided in the divided passage structure.