JPS5924121A - Combustion in combustor for gas turbine - Google Patents

Abstract

PURPOSE:To reduce the amount of NOx and improve combustion efficiency by a method wherein a part of fuel is burnt previously by a burner with a specified air rate while the remaining fuel is injected to the flame of the precombustion or the vicinity thereof and, further, is mixed with air, thereafter, is introduced to a part filled with catalyst. CONSTITUTION:A part of the fuel 1 and air 3 are mixed previously in the upstream side of the combustor so as to obtain the air rate of 60-90% while the mixed gas is burnt by the burner. The remaining fuel 1' is injected to the flame under combustion or the vicinity thereof to effect the precombustion of the fuel itself as well as the quenching of the flame simultaneously. The mixture is further mixed with the remaining air 3'. When the air is mixed after the quenching of the flame, the temperature of the mixture is risen sufficiently to a temperature necessary for the catalytic combustion when it arrives at the part 7 filled with the catalyst while the mixture contains no NOx substantially. Accordingly, the characteristics of the catalytic combustion system is utilized effectively and the efficient combustion may be effected as the whole of the combustor.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a combustion method for a gas turbine combustor used in a gas turbine power generation system, and more specifically, to a method for burning nitrogen oxides (hereinafter referred to as NOx) generated during combustion. ) The present invention relates to a combustion method for a catalytic combustion type gas turbine combustor that has a small amount of carbon dioxide and has 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 sought, and on the other hand, efficient use of energy resources has been required. Among the systems that can meet these demands, for example, gas turbine/steam turbine combined cycle power generation systems that use natural gas as fuel are being developed and are being studied. These gas turbine/steam turbine combined cycle power generation systems are
Compared to conventional power generation systems using fossil fuels, steam turbines have higher power generation efficiency, so in the future,
It is expected to be a power generation system that can effectively convert fuels such as natural gas, whose production is expected to increase, into electricity.

Gas turbine combustors used in gas turbine power generation systems traditionally burn a mixture of fuel and air.
It is ignited using a spark plug or the like to achieve homogeneous combustion. An example of such a combustor is shown in FIG. The combustor in Figure 1 has fuel nozzle 1 to +I+! ! The injected fuel is mixed with the fuel air 3, and the spar air is
It is ignited by lug 2 and burns. Then, the combusted gas is cooled and diluted to a predetermined turbine inlet temperature by adding cooling air 4 and dilution air 5, and then injected into the gas turbine from a turbine nozzle 6.

One of the serious problems with such conventional combustors is that a large amount of NOx gas is produced during fuel combustion.

The reason why the above-mentioned NOx is generated is due to the existence of a high temperature section during combustion of fuel. NOx
id:, Normally, nitrogen components are present in the fuel (if they are not present, nitrogen and oxygen in the combustion air react with each other according to the formula shown below to produce nitrogen components.

N2 + Ot'; 12NO In the above reaction, the higher the temperature, the more the reaction shifts to the right side and the amount of nitrogen monoxide (NO) produced increases. A portion of No is further oxidized to produce nitrogen dioxide (N02).

FIG. 2 shows the temperature distribution in the fluid flow direction in a conventional gas turbine combustor. As shown in the figure,
The temperature distribution within the combustor has a maximum value, and after reaching the maximum temperature, it is cooled down to a predetermined turbine inlet temperature by cooling and dilution air. The maximum temperature inside the combustor is 2
Since the temperature may reach as high as 000'C, the amount of NOx produced increases rapidly in this vicinity. In this way 1. Conventional gas turbine combustors have a problem in that they produce a large amount of NOx because of the presence of high-temperature parts. Therefore, it is necessary to install a flue gas denitrification device, etc., which poses problems such as the device becoming complicated. In order to solve these problems with gas turbine combustors, various combustion methods have been proposed. It is being considered.

As one of these, a heterogeneous combustion method (hereinafter referred to as catalytic combustion method) using a solid phase catalyst has recently been proposed for homogeneous reactions in the gas phase. The catalytic combustion method is
It uses a catalyst to combust a mixture of fuel and air. According to this method, combustion can be started at a relatively low temperature, no cooling air is required, and as the amount of combustion air increases, the maximum temperature becomes lower, and therefore, the generated NOx4i1 is extremely reduced. Is possible.

Furthermore, the turbine inlet temperature remains the same as in the conventional case, and the fuel can be completely combusted. FIG. 3 is a conceptual diagram of such a catalytic combustion type combustor, in which the catalyst filling portion 7 is filled with a catalyst body having a honeycomb structure. still,
If it is the same device or material as in Figure 1, the same reference numeral will be used.

In the above-mentioned catalytic combustion method, however, in order to use a catalyst to start the combustion reaction of the mixture of fuel and air, the mixture must be preheated to the temperature required for the catalytic combustion reaction. There are problems. In particular, it is known that when methane is used as a fuel, the ignition temperature is higher than when other fuels are used, so the preheating temperature must be increased.

Therefore, in order to solve the above-mentioned problems, it is conceivable to normally combust a part of the fuel before the catalyst filling part in the combustor to increase the temperature of the mixed gas. However, when normal combustion is performed, the temperature of the combustion gas becomes high as described above, and 1) NOx is generated. This NOx has a problem in that it is not decomposed in the catalyst filling section and is emitted as it is.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide an improved combustion method for a gas turbine combustor in which the amount of NOx generated during combustion is extremely small and the combustion efficiency is good.

[Summary of the invention]

The combustion method of a gas turbine combustor of the present invention is a gas turbine combustor that burns a mixed gas of fuel and air using a catalytic combustion method, in which at least a part of the fuel is contained in a stage upstream of a combustion catalyst filling part, and an air ratio is A mixture of 60 to 90% fuel and fallen air is pre-combusted in a burner, then the remaining fuel is injected into or near the pre-combustion flame, and the remaining air is mixed. This is characterized in that a mixed gas is introduced into the catalyst filling section.

In the following, the invention will be explained in more detail.

As a result of extensive research, the present inventors have found that, for example, when using a fuel such as methane that needs to be preheated to a relatively high temperature in order to start a catalytic combustion reaction, the following (
By adopting a one-year combustion method, the N
It has been found that catalytic combustion with a small amount of Ox and good combustion efficiency is possible.

That is, first, part of the fuel and air are premixed at the most upstream side of the combustor so that the air ratio becomes 60 to 90tj6, and this mixed gas is combusted using a burner. The combustion heat generated at this time is used for preheating the remaining fuel.

If the air fraction is less than 60 inches, the preheating temperature will not be that high and unburned kerf (soot) may be produced, while if it exceeds 90 degrees, NO
The amount of x generated increases.

The combustion gas released in the above combustion reaction contains unburned hydrocarbons and carbon monoxide produced by combustion.

Next, the remaining fuel is injected into the burning flame or its passages, thereby preheating the fuel itself and simultaneously quenching the flame. At this time, if the flame is not quenched by fuel injection, the next time the remaining air is mixed, all the fuel will be burned, resulting in a rise in temperature and an increase in the amount of NOx produced. It turns out. If quenching is performed here, even if air is introduced next time, a flame will not be generated, but a heated mixture of fuel and air will be sent to the catalyst filling section.

The remaining air is mixed with the quenched air-fuel mixture by injecting the remaining υ of fuel into this flame. When air is mixed after the 0 flame is quenched, the air-fuel mixture reaches the catalyst filling part. Sometimes, this air-fuel mixture is sufficiently heated to the temperature required for catalytic combustion and contains almost no NOx.

Therefore, the characteristics of the insect medium combustion system are fully utilized in the catalyst filling section, and efficient combustion is possible in the combustor as a whole.

The combustion catalyst used in the present invention may be any catalyst that is normally used as a combustion catalyst, such as noble metal catalysts such as platinum, noradium, rhodium, ruthenium, and iridium; M
Base metal catalysts such as n0z, CO2O3, Co3Q4, CuO, etc. are praised, and one or more types selected from the group consisting of these are used.In addition, the catalyst body used in the present invention is The above-mentioned combustion catalyst is supported on a ceramic or a side-heating alloy formed into a honeycomb shape or the like. Gansho 56-187
No. 760 Mei&llIA1- or Patent Application No. 57-66275
It is preferable to form the structure as described in the specification of the above patent.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.

[Embodiments of the invention]

A simulating device for a power turbine combustor was fabricated using a nickel alloy cylinder with an inner diameter of 100 mm and a height of 50 CJmm. Ceramic was formed into a honeycomb structure at the most downstream part of the combustor in the fluid flow direction, and a catalyst body having a length of lO'o1+m and supporting a palladium catalyst was filled therein.

Methane is used as fuel, the amount of air supplied to the entire combustor is 160ONl/mI7+, and the amount of methane supplied is 48
Nl was set to 7 mm.

A burner was installed at the most upstream side of the combustor, a first gas inflow hole was provided 150 mm downstream from the burner, and several second gas inflow holes were further provided 100 mm downstream. During the experiment, air and methane were each preheated to 300°C and introduced into the combustor.

Under the above conditions, the air ratio of the burner at the most upstream is set to 7.
0q6, and after igniting the mixed gas of methane and air with an igniter, the remaining methane was introduced from the first gas inlet, and the remaining air was introduced from the second gas inlet. catalytic combustion.

Then, the concentration of unburned matter at the combustor outlet was measured, and the amount converted to methane and the NOx concentration at the outlet were measured. The results are shown as a in FIG. 4.

At the same time, as comparative examples, B: The entire amount of air and methane was introduced into the combustor as it was without being divided and was burned without ignition from the outside, C: The air heavy metal of the burner at the most upstream was set to 130φ. , ignited with an igniter, but burned in the same manner as in a, and d: The air rate of the burner at the most upstream was 70 degrees, and after ignited with an igniter, the first and second gas inflow holes were ignited. The unburned gas concentration and NOx concentration at the combustor outlet were measured in the same manner as in a for each case in which a Jf gas mixture of methane and air was introduced and combusted. The results are simultaneously shown in FIG.

As is clear from FIG. 4, it was confirmed that, according to the combustion method of the present invention, almost no unburned methane remained, and complete combustion was achieved. Furthermore, it was confirmed that there was almost no generation of NOx, and low NOx combustion was possible.

On the other hand, in the combustion method b, almost no methane is burned, and the catalytic combustion reaction by the catalyst does not start at a preheating temperature of about 300°C.

Also, with the combustion method of C, there is almost no unburned methane,
It was confirmed that a large amount of NOx was produced. This is considered to be because the air ratio in the burner is high, so a large amount of NOx is generated during preliminary combustion, and this is emitted as is.

Furthermore, the same results as C were obtained with the combustion method d. This is because the flame combusted in the burner is not sufficiently quenched, and the methane introduced from the first and second gas inflow holes burns before the catalyst filling section, causing the temperature to rise. it is conceivable that.

〔Effect of the invention〕

According to the combustion method of the present invention, it is possible to burn fuel extremely efficiently, and since the amount of NOx produced during combustion is small, problems such as environmental pollution do not occur. Furthermore, since part of the fuel is combusted to raise the temperature of the fuel/air mixture, the preheating temperature can be lowered, which is advantageous in terms of energy saving.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of a normal gas turbine combustor, Fig. 2 is a diagram showing the temperature distribution inside a normal gas turbine combustor, and Fig. 3 is a diagram showing the temperature distribution inside a normal gas turbine combustor.
The figure is a conceptual diagram of a catalytic combustion type gas turbine combustor, and Figure 4 shows changes over time in the concentration of generated NOx and unburned methane concentration due to differences in the combustion method of the catalytic combustion type combustor in the example. FIG. 1... Fuel nozzle, 2... Snoke plug, 3...
... Combustion air, 4... Cooling air, 5... Dilution air, 6... Turbine nozzle, 7... Honeycomb I
Ii formed catalyst.

Claims (1)

[Claims] In a gas turbine combustor that burns a gaseous mixture of fuel and air using a catalytic combustion method, the combustion catalyst light (ii) contains at least a part of the fuel and has an air ratio of 60 to 90 cm. The mixed gas of fuel and air is pre-combusted in a burner, the remaining fuel is injected into the pre-combustion flame or its vicinity, the remaining sharp air is mixed, and the mixed gas is sent to the catalyst filling section. A combustion method for a gas turbine combustor, characterized in that the combustion method is introduced into a gas turbine combustor.