JP2672510B2 - Catalytic combustion type gas turbine combustor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas turbine combustor, and more particularly to a catalytic combustion type gas turbine combustion in which the amount of nitrogen oxides (NO _X ) generated is small. Regarding vessels. (Technical background of the invention and its problems) In recent years, various alternative energies have been required along with depletion of petroleum resources and the like, but at the same time, efficient use of energy resources is also required. Among those that meet these demands are, for example, a gas turbine / steam turbine combined cycle power generation system or a coal gasification gas turbine / steam turbine combined cycle power generation system that uses natural gas as a fuel, 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, and therefore natural gas whose production is expected to increase in the future. It is expected as a power generation system that can effectively exchange fuels such as coal and gasification gas into electric power. By the way, in the gas turbine combustor used in the gas turbine power generation system, a mixture of fuel and air is ignited by using a sparse plug or the like to perform homogeneous combustion from the future. An example of such a combustor is shown in FIG. In the combustor shown in FIG. 2, the fuel injected from the combustion nozzle 1 is mixed with the combustion air 3, ignited by the spark plug 2 and burned. And
Cooling air 4 and dilution air 5 are added to the burned gas, that is, combustion gas, and after being cooled and diluted to a predetermined turbine inlet temperature, they are injected into the gas turbine from a turbine nozzle 6. 8 is a swirler. One of the serious problems in such a conventional combustor is that a large amount of NO _X gas is generated during combustion of fuel to cause environmental pollution. The reason why the above NO _X is generated is that when the fuel is burned, it is partially 2000
This is because there is a high temperature part that exceeds ℃. In order to solve such problems of the gas turbine combustor, various combustion methods have been studied. Recently, a heterogeneous combustion method using a solid-phase catalyst (hereinafter referred to as a catalyst combustion method) has been proposed. In this catalytic combustion method, a lean fuel that is not burned in an ordinary combustor can be burned by using a catalyst, so that the fuel temperature does not become high enough to generate NO _X. Further, the turbine inlet temperature can be made the same as the conventional one. FIG. 3 is a conceptual diagram of an example of a combustor used in this catalytic combustion method. The numbers in the figure represent the same elements as in FIG. This combustor is structurally characterized in that it is provided with a catalyst filling section 7. The catalyst filling portion 7 is usually filled with a combustion catalyst having a honeycomb structure, in which a mixed gas of fuel and air is burned. Reference numeral 1'denotes a fuel nozzle for supplying fuel for catalytic combustion. However, in such a catalytic combustion system, since most of the fuel is burned in the catalyst filling portion, there is a problem that the temperature of the catalyst becomes high, the thermal deterioration is remarkable, and the life is short. Further, it was difficult to cope with the high temperature of the gas turbine inlet because of the heat resistance of the catalyst. Therefore, the inventors of the present invention only burn a part of the required fuel in the catalyst-filled portion, further add fuel downstream of the catalyst, and cause vapor-phase combustion (non-catalytic thermal combustion) in that portion. Has already proposed a catalyst combustion method in which the temperature of the catalyst is lower than before and the life is long. Although it is important to add the fuel downstream of the catalyst as described above, a new problem arises here. That is, the gas phase combustion downstream of the catalyst is NO _x.
Since the combustion is lean in terms of suppression, local misfire or the like occurs in the combustion section, and the combustion becomes unstable. (Problems to be Solved by the Invention) As described above, in the conventional catalytic combustion type gas turbine combustor, when most of the fuel is burned in the catalyst filling portion, the life of the catalyst is shortened, while When a part of the gas is burned in the catalyst-filled portion and the rest is gas-phase burned downstream of the catalyst, the gas-phase combustion becomes unstable. The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas turbine combustor of a catalytic combustion type, which has long-term durability and can perform stable gas-phase combustion downstream of the catalyst body. To do. [Structure of the Invention] (Means for Solving Problems) The inventors of the present invention have a structure in which a swirl generating unit is provided between a catalytic combustion unit and a gas-phase combustion unit, and the flow path is narrowed and then rapidly expanded. As a result, it was found that the gas phase combustion can be stabilized, and the present invention was completed. That is, the catalytic combustion type gas turbine combustor of the present invention is provided with a mixing section that mixes fuel and air into a fuel mixture, and is provided on the downstream side of the mixing section, and burns the fuel mixture with a catalyst. Of the catalytic combustion part to be made, and a gas phase combustion part which is provided on the downstream side of the catalytic combustion part and which causes the fuel mixture which remains unburned in the catalytic combustion part to undergo gas phase combustion, and the catalytic combustion part and the gas phase combustion part. And a vortex flow generating part for generating a vortex flow of the fuel mixture in the gas phase combustion part, and the upstream side of the vortex flow generating part is formed into a bellmouth-shaped curved surface, and the downstream side. Is formed with an end surface portion that is substantially perpendicular to the flow direction of the fuel mixture. (Operation) In the catalytic combustion type gas turbine combustor of the present invention, after the flow velocity is increased in the bellmouth-shaped curved surface portion on the upstream side, a stable vortex flow is generated in the gas phase combustion portion on the downstream side. As a result, the flame holding effect is brought about and the gas phase combustion is stabilized. Embodiment An embodiment of the present invention will be described below with reference to FIG. Here, the members designated by the same reference numerals as in FIGS. 1 and 2 represent the same members as in the conventional example. Referring to FIG. 1, a fuel such as methane which is heated to 300 ° C. to 500 ° C. by a separately provided compressor or the like (not shown) 9
Are injected from the fuel nozzle 10. The fuel 9 is mixed with the combustion air 3 in the mixing section 11 formed in the combustor to form a fuel mixture. This fuel mixture flows into the catalyst body 7 and ignites and burns. At this time, if the mixing ratio / flow rate of the fuel mixture and the size (surface area) of the catalyst are set to predetermined values,
In the catalyst body, only a part of the supplied fuel mixture is burned, and the remaining portion is heated, and is discharged downstream from the catalyst body 7. The mixing ratio and the like are particularly determined so that the temperature of the catalyst body 7 does not become too high. If necessary, an auxiliary nozzle (auxiliary fuel mixture supplying section) for supplying an auxiliary fuel mixture may be provided on the downstream side of the catalyst body 7. The supplemental fuel mixture typically consists of fuel only, but it may also consist of fuel and supplemental fuel air. Further, this fuel mixture is set to be a relatively lean gas because it does not raise the combustion temperature in the gas-phase combustion section described later. This is because, as described above, increasing the temperature of gas phase combustion leads to the generation of NO _X. In this example, such an auxiliary nozzle was provided downstream of the catalyst body. The fuel mixture from the catalyst body 7 and the auxiliary fuel mixture from the auxiliary fuel nozzle 12 are mixed, and a desired mixed fuel flow is sent downstream. Then, on the downstream side of the auxiliary fuel flow nozzle 12, a throat portion (vortex flow generating portion) 13 for generating a swirl in the mixed fuel flow, and a gas phase for combusting the mixed fuel flow in a gas phase. A combustion section 14 is provided. The upstream side of the throat portion 13 is formed into a bellmouth-shaped curved surface, and the downstream side is formed to have an end face portion perpendicular to the flow direction of the lean fuel flow. Further, the minimum inner diameter d ₁ of the throat portion is almost equal to the inner diameter d ₂ of the gas phase combustion portion 14.
It is formed from 1 / 1.2 to 1 / 1.5. A more specific shape of the throat portion 13 is, for example, the ISA1932 nozzle (JISZ 8762
-1969). By doing so, the pressure loss due to the throat portion 13 can be minimized. Therefore, the lean fuel flow that has flowed in from the upstream side is gradually contracted by the throat portion 13, and then the gas-phase combustion portion 14
Is rapidly expanded by and forms a stable vortex flow (circulation flow) 15 along the periphery of the gas phase combustion section behind the throat section 13. The vortex 15 is a stable vortex because it is not so much affected by the turbulence of the mixed fuel flow passing through the center of the flow path of the throat portion 13, if any. A spark plug 2 for igniting the lean fuel flow is provided on a side wall of the combustor near the swirl flow 15 and surrounding the gas phase combustion section 14. The ignition plug 2 is drawn out from the post-ignition gas phase combustion section 14 in order to avoid a high temperature during gas combustion. Therefore, the mixed fuel flow is ignited by the spark plug 2 and the gas phase combustion is started. Here, since the mixed fuel flow is lean as described above, there is a tendency for local misfire and unstable combustion. Further, the fact that the flow velocity of the mixed fuel flow is as high as several tens of meters per second also contributes to the combustion instability. However, in the combustor of the present embodiment, since a vortex flow is generated along the periphery of the gas-phase combustion portion, a flame holding effect occurs in this portion, and even if the local misfire or the like occurs, it does not expand. Instead, the original homogeneous combustion state is immediately restored. Therefore, according to the present embodiment, stable and uniform vapor phase combustion can be easily performed in the vapor phase combustion section. Further, since the throat portion 13 has the bell mouth structure as described above, the pressure loss due to the throat portion 13 can be minimized. It should be noted that in the above-mentioned embodiment, pre-combustion is not performed on the upstream side of the catalyst, but this is based on the assumption that a fuel and a catalyst that can act even at low temperatures are used, and if pre-combustion is required. For example, it is possible to provide a pre-burning section as shown in FIG. Further, although a part of the inflowing fuel mixture is burned in the catalyst body 7, almost all of it may be burned. Further, the fuel added downstream of the catalyst may be mainly fuel, and steam or other gas may be mixed. The diameter of the gas phase combustion section downstream of the throat section may be required to be smaller than the diameter of the throat section upstream depending on the space where the combustor is installed. It is possible to make the ratio of the diameter d ₂ of the gas phase combustion section to the diameter d ₁ 1.0 or more. However, it goes without saying that the flow path diameter ratio d ₂ / d ₁ can be variously selected depending on the type of fuel. Hereinafter, the experimental results using the above-mentioned examples and comparative examples will be described in detail. Experimental Example A Using a simulated combustor with an expansion ratio of 1.5 (the diameter of the gas phase combustion section is 100 mm, which is the same as the catalyst body) as shown in Fig. 1, the fuel is natural gas, the catalyst body has a diameter of 100 mm, and a length of 100 mm. Combustion was carried out using the above noble metal honeycomb catalyst body. A mixed gas consisting of natural gas and combustion air is heated to 450 ° C and heated to 500 ° C.
Adiabatic flame temperature of 1100 at a flow velocity of 20 m / s to 50 m / s in conversion
A mixed gas having a temperature of ℃ was flown into the catalyst body. In addition, the supply port from the auxiliary fuel supply section was installed 30 mm downstream of the catalyst body, the throat section was installed 50 mm downstream of the catalyst body, and the combustion gas sampling was installed 500 mm downstream of the catalyst body. The fuel from the auxiliary fuel supply unit is 30
It was supplied at 0 ° C. The results when the flow rate was changed are shown in Table 1 below. As a comparative example, the case where the throat part is not installed under the same conditions is also shown. Note that NO _X at the time of combustion was 5 ppm or less. Experimental Example B Using a simulated combustor with an expansion ratio of 1.2 (the diameter of the gas-phase combustion section was reduced to 80 mm for the catalyst body diameter of 100 mm) as shown in FIG. 1, combustion was performed under the same conditions as in Experimental Example A. The results when the flow rate was changed are shown in Table 2. As a comparative example, the case where the throat part is not installed is also shown (same as Table 1). Note that NO _X at the time of combustion was 5 ppm or less. The catalytic combustor according to the present invention stably exhibits a very high combustion efficiency without misfire even at a high flow rate required for a gas turbine, whereas in the comparative example, a misfire occurs as the mixed gas flow rate stops. It was Furthermore, the pressure loss due to the throat was a negligible value. [Effects of the Invention] As can be understood from the above-described embodiments of the invention, according to the present invention, the configuration of the vortex flow generating portion is such that the upstream side is formed into a bellmouth-shaped curved surface, and the downstream side is the fuel mixture. Since the structure is formed with end faces that are substantially perpendicular to the flow direction, the lean fuel flow that has flowed into the vortex flow generation part is gradually and gradually contracted to increase the flow velocity, and then the gas phase combustion part. It expands rapidly and a stable vortex is generated on the downstream side of the end face, and the flame holding effect is improved by the generation of this vortex, and even if a local misfire occurs, the original uniform combustion state is immediately generated. It will be recovered to. Further, since the upstream side of the vortex flow generating portion is formed into a bell-mouth-shaped curved surface, there is no discontinuous structure up to the end face portion, and it is possible to reduce pressure loss,
A stable vortex flow can be generated. Therefore, stable gas combustion can be performed without increasing the temperature of the catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional explanatory view of a catalytic combustion type gas turbine combustor according to an embodiment of the present invention, and FIG. 2 is a sectional explanatory view of a conventional gas phase combustion type gas turbine combustor. FIG. 3 is a cross-sectional explanatory view of a conventional catalytic combustion type gas turbine combustor. 7 ... Catalyst 13 ... Throat 14 ... Gas-phase combustion 15 ... Eddy current

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kenjiro Igawa               2-4-1 Nishiazajigaoka, Chofu-shi, Tokyo               TEPCO Technical Research Institute (72) Inventor Terunobu Hayata               1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa               Toshiba Research Institute, Ltd. (72) Inventor Tomiaki Furuya               1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa               Toshiba Research Institute, Ltd. (72) Inventor, Yamanaka               1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa               Toshiba Research Institute, Ltd. (72) Inventor Junji Kozuka               1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa               Toshiba Research Institute, Ltd.                (56) References JP-A-60-202205 (JP, A)                 JP-A-60-122807 (JP, A)                 63-126766 (JP, U)

Claims (1)

(57) [Claims] A mixing section that mixes fuel and air into a fuel mixture, a catalytic combustion section that is provided on the downstream side of the mixing section and burns the fuel mixture with a catalyst, and a catalytic combustion section that is provided on the downstream side of the catalytic combustion section. And a gas-phase combustor for combusting the fuel mixture that remains unburned in the catalyst-combustion part in a gas-phase, and the fuel mixture provided in the gas-phase combustor and between the catalyst-combustion part and the gas-phase combustor. And a vortex flow generating part for generating a vortex flow, the upstream side of the vortex flow generating part is formed into a bellmouth-shaped curved surface, and the downstream side has an end face portion substantially perpendicular to the flow direction of the fuel mixture. A gas turbine combustor of a catalytic combustion type, which is characterized in that it is formed. 2. The catalytic combustion according to claim 1, further comprising an auxiliary fuel mixture supply unit for supplying an auxiliary fuel mixture between the catalytic combustion unit and the circulation flow generation unit. Type gas turbine combustor.