JPS60205128A - Combustor for gas-turbine - Google Patents

Abstract

PURPOSE:To restrict generation of high-temperature section locally which generates NOx and promote combustion to improve combustion efficiency by a method wheein a mixing means is provided between the rear end of catalyst and a position whereat the outflow product of the catalyst generates non-catalytic thermal combustion together with supplementary fuel. CONSTITUTION:Fuel from a fuel nozzle 1 is ignited by spark plugs 2 to effect precombustion and the fuel is supplied further through another fuel nozzle 9 there, the fuel becomes mixture whose tempeature is increased to a temperature whereat the catalyst is acting and the mixture is supplied to a catalyst loading section. The supplementary fuel, added into the downstream area of the catalyst, is injected through a small hole 13, bored on the blade 12 of a swirler, from inside of the swirler 11 provided as the mixing means. Acccording to this method, the concentration of generated NOx is reduced, the combustion efficiency is improved and, especially, the generated amount of NOx may be reduced extremely as compared with prior art in case the temperature of combustion gas, discharged into the turbine in order to improve the efficiency of the turbine, is increased within a predetermined range, i.e. an adiabatic flame temperature is high.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a gas turbine combustor used in a gas turbine power generation system, and more specifically, to a gas turbine combustor used in a gas turbine power generation system. The present invention relates to a catalytic combustion type gas turbine combustor that has low combustion efficiency and good combustion efficiency.

[Technical background of the invention and its problems]

In recent years, with the depletion of petroleum resources and the like, various alternative energies have been required, and at the same time, efficient use of energy resources has also been required. Examples of systems that can meet these demands include gas turbine/steam turbine combined cycle power generation systems that use natural gas as fuel or coal gasification gas turbine/steam turbine combined cycle power generation systems, which are currently being studied.

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. It is expected to be a power generation system that can effectively convert fuels such as coal and gasified gas into electricity.

Conventionally, in a gas turbine combustor used in a gas turbine power generation system, a mixture of fuel and air is ignited using a spark plug or the like to perform homogeneous combustion. An example of such a combustor is shown in the conceptual cross-sectional view of FIG. In the combustor shown in FIG. 1, fuel injected from a fuel nozzle 1 is mixed with combustion air 3, ignited by a spark plug 2, and combusted. and,
Cooling air 4 and dilution air 5 are added to the burned gas, that is, the combustion gas, and the air is cooled and diluted to a predetermined turbine inlet temperature, and then injected into the gas turbine from a turbine nozzle 6. 8 is a swirler. One of the serious problems with such conventional combustors is that a large amount of NOx gas is generated during fuel combustion, causing environmental pollution.

The reason why the above-mentioned NOx is generated is that during fuel combustion, there is a high-temperature part that exceeds 1500° C. in the combustor.

In order to solve these problems with gas turbine combustors, various combustion systems are being studied.

Recently, a heterogeneous combustion method using a solid phase catalyst (hereinafter referred to as a catalytic combustion method) has been proposed.

This catalytic combustion method uses a catalyst to combust lean fuel that would not be combusted in a normal combustor. Therefore, the combustion temperature does not reach a high enough temperature to generate NOx, and almost no NOx is generated. .

FIG. 2 is a conceptual cross-sectional view of an example of a combustor used in a catalytic combustion system. Each number in the figure represents the same element as in FIG. A structural feature of this combustor is that it includes a catalyst filling section 7. The catalyst filling section 7 is normally filled with a combustion catalyst having a honeycomb structure, and a mixture of fuel and air is combusted here. In the combustor shown in Fig. 2, fuel injected through a fuel nozzle 1 and combustion air 3 are mixed, ignited by a spark plug 2 to precombust and serve as a preheat source, and then fuel is injected from a fuel nozzle 1'. The mixture is heated to the temperature required to react with the catalyst.

However, this catalytic combustion method also has the following drawbacks. In other words, in the conventional catalytic combustion method, most or all of the fuel is combusted by both the catalytic reaction and the gas phase reaction in the catalyst that is completely filled in the catalyst filling section. Thermal deterioration is large and the lifespan is short. Furthermore, it is difficult to cope with high temperatures comparable to the gas turbine inlet temperature due to the heat resistance of the catalyst. Therefore, the present inventors decided that the catalyst filled in the catalyst filling part would only burn a part of the fuel through the catalytic reaction, and further added an auxiliary fuel mainly composed of fuel downstream of the catalyst, in which the gas Phase combustion (non-catalytic thermal combustion) allows the temperature of the catalyst during combustion to be lower than before, and a long-life catalytic combustion method has already been proposed. In addition, even in the conventional catalytic combustion system, if supplementary fuel is added downstream of the catalyst and a combustor is installed there, the load on the catalyst will be reduced by that amount, extending its life.
It can be easily inferred that increasing the gas turbine inlet temperature is advantageous. A new problem arose as to whether it is important to add auxiliary fuel downstream of the catalyst in this way. That is, when supplementary fuel is added to cause further combustion, NOx is generated and the total amount of NOx increases. This is because the added auxiliary fuel is burned before being sufficiently mixed with the effluent from the catalyst, resulting in local high temperature areas where NOx production rapidly increases. Furthermore, there are cases in which the additional supplementary fuel is not necessarily fully combusted and is discharged unburned. This is because the fluid flow in the space after supplementary fuel is added is not suitable for combustion.

[Object of the Invention] The present invention is directed to a gas turbine combustor using a catalytic combustion method, in which supplementary fuel is added downstream of the catalyst to perform non-catalytic thermal combustion. An object of the present invention is to provide a gas turbine combustor which suppresses the generation of NOx and promotes combustion to improve combustion efficiency.

[Summary of the invention]

As a result of intensive research to achieve the above object, the inventors of the present invention discovered that the effluent is located between the rear end of the catalyst and the area where the effluent from the catalyst causes non-catalytic thermal combustion together with supplementary fuel. This objective can be achieved by providing a stirring means to stir and mix the auxiliary fuel and at the same time give a swirling flow to the flow in order to efficiently cause non-catalytic combustion. I came to the conclusion that there is.

One structural example of the combustor of the present invention is shown in the conceptual cross-sectional view of FIG. Numbers in the figure that are the same as in FIG. 2 represent the same elements. 11 is a swirler used as a stirring means. Third
In the combustor shown in the figure, combustion air 3 and fuel supplied from a fuel nozzle 9 are mixed to form a mixture, which passes through a catalyst filling section 7. A part or most of the mixture burns with the catalyst filled in the catalyst filling part 7 and flows out from the catalyst filling part] 7 After forming an effluent, the auxiliary fuel flows out from the auxiliary fuel nozzle 10. added to things.

The added supplementary fuel is mixed with the effluent by the swirler 11, and a swirling flow is imparted to the flow. Then, it is ignited by the spark plug 2 to ignite the non-catalytic Funaki. Depending on the fuel and catalyst 119, it is also possible to ignite using the effluent from the catalyst as a heat source without using such an ignition means. In Figure 3, pre-combustion is not performed on the upstream side of the catalyst, but this is based on the assumption that a fuel and catalyst that can act as a catalyst even at low temperatures are used.If pre-combustion is necessary, the second It is also possible to provide means for pre-combustion as shown in the figure.

Further, the auxiliary fuel added to the downstream region of the catalyst may be mainly composed of fuel, or may contain steam or other gas.

Figure 4 shows an example of a swirler. This swirler has a structure with blades for controlling the flow.

In the present invention, the shape of the stirring means such as a swirler is not limited, and any shape normally used in gas turbine combustors can be applied.

The present invention is not limited to FIG. 3, but for example, FIG.
A gas turbine combustor as shown in the conceptual cross-section in the figure is also possible. In FIG. 5, fuel from fuel nozzle /I/1 is ignited by spark plug 2 and pre-combusted, and then fuel is further supplied from fuel nozzle 9 to form a mixture heated to a temperature at which the catalyst acts. This is supplied to the catalyst filling section. The auxiliary fuel added to the downstream region of the melting medium is inserted from the inside of the swirler 11 used as a stirring means through small holes 1 made in the surface of the blades 12 of one swirler, as shown in the partial view of FIG.
3 yoshi squirts.

[Example of the present invention]

Example-1 The schematic diagram in FIG. 7 shows a simulated combustor with an inner diameter of 100 mm for demonstrating the effects of the present invention. 450 from the combustor upstream side
A mixture t4 of fuel (natural gas) and air heated to 0.degree. C. was supplied to the catalyst filling section 7. Fuel (natural gas) was added from the lower fuel nozzle 10 of the catalyst, passed through a swirler 11 used as a stirring means, and burned. Spark plug 2 was used for ignition. The flow velocity immediately before the catalyst filling section 7 was 20 m/lax.

The auxiliary fuel nozzle 10 had an inner diameter of 5 mm, and the tip of the nozzle also had a hole of 5 mm. The experiment was conducted by setting the adiabatic flame temperature of the mixture at the catalytic converter to 1050° C. and changing the fuel flow rate from the auxiliary fuel nozzle 10 to adjust the adiabatic flame temperature of the combustion gas discharged to the final pheasant turbine. The experiment was conducted by measuring the combustion efficiency and NOx concentration with and without the swirler 11 installed. Gas sampling was performed at 30c+n downstream of the catalyst. The results of the experiment are shown in the characteristic diagram of FIG. In the figure, the horizontal axis is the adiabatic flame temperature after fuel addition. The curve ma is the combustion efficiency in the case of the present invention, the curve C is the combustion efficiency in the conventional example, the curve C is the NOx concentration in the present invention, and the curve d is the NOx concentration in the conventional example. In the figure, the NOx in the conventional example rises rapidly as the adiabatic flame temperature rises. This is because the added supplementary fuel burns before being sufficiently mixed with the effluent from the catalyst, resulting in local high temperatures. It is thought that this was due to a sudden increase in NOx. The NOx concentration in the present invention is lower than that of a conventional type combustor without Swan-11, and the combustion efficiency is also improved. The improvement in combustion efficiency is thought to be due to the generation of swirling flow by the swirler.

Example-2 Using the same device as in Example-1, a device that also serves as a swirler and a fuel nozzle as shown in Figs. 5 and 6 was used instead of the auxiliary fuel nozzle 10 and swirler 11 in Example-1. An experiment similar to that in Example 1 was conducted using the same. The results are shown in the characteristic diagram of FIG. In this example as well, good results were obtained in terms of combustion efficiency and NOx concentration, as in Example-1.

〔Effect of the invention〕

As is clear from the above explanation, the gas turbine combustor according to the present invention generates a lower concentration of NOx and has improved combustion efficiency compared to conventional ones. When the temperature of the emitted combustion gas is raised within a predetermined range, that is, when the adiabatic flame temperature is high, the amount of NOx generated can be significantly lower than in the conventional case.

[Brief explanation of the drawing]

Figure 1 is a conceptual cross-sectional view of a normal gas turbine combustor;
The figure is a conceptual cross-sectional view of a conventional catalytic combustion type gas turbine combustor, Figures 3 and 5 are conceptual cross-sectional views showing an example of the gas turbine combustor of the present invention, and Figure 4 is a conceptual cross-sectional view of a gas turbine combustor of the present invention. A conceptual diagram showing a swirler which is one example of the means, FIG. 6 is a partial diagram of another example of the stirring means according to the present invention, and FIG. 7 shows a simulated combustor used in Example-1. The schematic diagram, FIG. 8, and FIG. 9 are characteristic diagrams obtained in Example-1 and Example-2. 1.1', 9...Fuel nozzle, 2...Spark plug, 3
... Combustion air, 4. Cooling air, 5. Dilution air, 6.
... Turbine nozzle, 7. Catalyst filling section, 8.11.
・Swirler 110・Auxiliary fuel nozzle, 12・Swirler
Feather, 13 small holes. Agent Patent Attorney Kensuke Chika (and others) No. 1
Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure I Figure 8 Flexibility (b)

Claims (1)

Scope of Claims: (1) In a gas turbine combustor using a catalytic combustion method, a first means for mixing fuel and air to form a mixture; and a first means for forming a mixture by bringing the mixture into contact with a catalyst; a second means for partially combusting the effluent, and a third means for performing non-catalytic thermal combustion in the downstream region of the catalyst after adding supplementary fuel mainly consisting of fuel to the effluent from the second means. 1. A gas turbine combustor comprising: a stirring means installed between the rear end of the catalyst and a region where non-catalytic thermal combustion occurs. gas turbine combustor. (3) The gas turbine combustor according to claim 1, wherein the stirring means also serves as means for adding supplementary fuel.