JPS6141810A - Burning flame formation gas turbine - Google Patents

Abstract

PURPOSE:To reduce effectively thermal NOx produced in burning time by a method wherein a fuel jetting nozzle is utilized for forming a low excess air ratio burning flame and plural fuel jetting nozzles are arranged in concentric circle manner on the outer periphery of the fuel jetting nozzle for forming a high excess air ratio burning flame. CONSTITUTION:Fuel is jetted through a nozzle 10, the air required for burning is jetted through an air port 30, a low excess air ratio burning flame 50 having the excess air ratio less than 1.0 is formed. Meantime, the fuel is jetted through nozzles 20, the air required for the burning is jetted through air ports 40, a high excess air ratio burning flame 60 having the excess air ratio more than 1.0 is formed. Thermal NOx produced by the high excess air ratio burning flame 60 and a material for reducing the NOx produced by the low excess air ratio burning flame 50 are mixed sufficiently in a mixing region 70. Thereby, the NOx is changed to a harmless nitrogen by the reaction between said NOx and the material. Accordingly, the burning can be performed under the less amount of NOx producing condition.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to the structure of a gas turbine combustor, and more particularly to a combustor suitable for reducing nitrogen oxide GLJ (hereinafter referred to as NOx) generated during combustion. .

[Background of the invention]

NOx generated during combustion in a gas turbine combustor is caused by nitrogen in the air called thermal NOx.

The generation mechanism of thermal NOx is explained by the Zeldovich mechanism. In other words, ``Due to the following three elementary reactions.

N! +0 → No + N (1) N+
0*→ NO+ 0 (2) N + O
H--NO+H (3) According to these reaction equations, it can be seen that the generation of nitrogen atoms by the dissociation reaction of nitrogen molecules represented by equation (1) is an initiation reaction. In formula (1), a nitrogen atom N is generated, and in formulas (2) and (3), that N is oxidized by an oxygen molecule and a water radical to become NO. In diatomic molecules such as
Nitrogen-nitrogen bonds, where the distance between them expands and contracts rapidly, are easily broken.

Therefore, as the temperature rises, the dissociation reaction of nitrogen molecules (N3) will occur violently! 0, the reaction equation (1) proceeds further.

As described above, it can be explained that the amount of thermal NOx produced increases as the temperature rises.

That is, in order to reduce the generation of thermal NOx, it is necessary to prevent the reaction of formula (1) from proceeding. And in order to do that, it is important not to raise the temperature. The current method for converting gas turbine combustors to tN Ox is to cool the flame with a large amount of air so as not to increase the temperature of the flame.

That is, the air ratio of the combustion flame is extremely high. The air ratio is the ratio between the minimum amount of air (theoretical air amount) required to completely burn the supplied fuel and the amount of air actually introduced. Even after such measures, NOx in exhaust gas
The concentration is preferably about 1100 ppm, and in view of recent environmental issues, a concentration of 60 ppm or less is desired.

A conventional low NOx combustion method for a gas turbine combustor will be explained with reference to FIG. That is, as mentioned above, this is a so-called lean combustion method in which the flame temperature is lowered with a large amount of air.Fuel is supplied from the nozzle 10 (b), and air is further injected from the nozzle 10 (b). Ru. At that time, the fuel and air are tt-controlled so that the air ratio becomes extremely large. That is, the flame 300 becomes a high air ratio combustion flame. To this end, various efforts were made. For example, in the method described in Japanese Utility Model Publication No. 57-154853, when the air pressure is low, air is supplied using the gas turbine casing pressure to achieve lean combustion as stable as possible. Further, Japanese Utility Model Application Publication No. 57-150373 relates to an air introduction device for a gas turbine combustor, which performs lean combustion for a low NOx ratio.

[Purpose of the invention]

An object of the present invention is to solve the above problems by using other NO.
By considering a low NOx combustion method from the viewpoint of X production reaction and improving the structure of the conventional gas turbine combustor, thermal NOx generated during combustion can be reduced! An object of the present invention is to provide a gas turbine combustor that can effectively reduce

[Summary of the invention]

That is, the feature of the present invention is that in a gas turbine combustor,
A fuel injection nozzle for forming a low air ratio combustion flame and a plurality of fuel injection nozzles for forming a high air ratio combustion flame are arranged concentrically around the outer circumference of the nozzle. Note that a low air ratio combustion flame is one in which the air ratio is 1.0.
A high air ratio combustion flame is one in which the air ratio is 1.0 or more.

In addition, in a low air ratio combustion flame, a reducing agent for nitrogen oxides is generated, and in a high air ratio combustion flame, nitrogen oxides (thermal NOx) are generated, and the reducing agent and nitrogen oxides are transferred into the gas turbine combustor. One of the features is that it can be mixed with.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is an example of a gas turbine combustor according to the present invention. The nozzle 10 is for forming a low air combustion flame, and a plurality of nozzles 20 for forming a high air ratio combustion flame are arranged concentrically around the nozzle.

Fuel for the gas turbine combustor (usually using methane or the like) is ejected from the nozzle 10, and air necessary for combustion is ejected from the air port 30. Airbow 430 is the first
As shown in the figure, there are concentric circles [4] around the outer periphery of the nozzle 10. Therefore, a low air ratio combustion flame 50 is formed. The amount of fuel and air is controlled so that the flame has an air ratio of less than 1.0.

Further, from the nozzle 20, fuel for the gas turbine combustor (
The air necessary for combustion is ejected from the air port 40. As shown in FIG. 1, the air port 40 is arranged in a plurality of boats around the outer periphery of the turbine combustor and extends to the flame trailing stream. Therefore, the high air ratio combustion flame 6
form 0.

The fuel and air 1 are controlled so that the flame has an air ratio of 1.0 or more.

Therefore, the thermal NOX generated by the high air ratio combustion flame 601/C and the N0 generated by the low air ratio combustion flame 50
By sufficiently mixing the xt-reducing substance in the mixing region 70, low NOx combustion is achieved.

The principle of the present invention is shown below.

FIG. 2 shows an experimental apparatus for verifying the principle of the present invention, and FIGS. 3 and 4 show the experimental results.

First, the experimental method will be explained. Conduit 80 supplies a premixed gas of methane gas and air, which is ejected from nozzle 81 to form flame 82 into combustor 90 . The exhaust gas of the flame is sampled from the probe 100 and analyzed using gas chromatography and a NOx meter. The air ratio is calculated from the exhaust gas analysis value. Regarding the influence of air ratio on thermal NOx generated by the flame,
Firstly, a certain amount of nitrogen monoxide (No. 2, methane gas and air is added to the premixed gas) into the conduit 80.
Form a flame. Regarding the flame, the relationship between N08 degrees in the exhaust gas and the air ratio is measured. Note that the air ratio was changed by changing the amount of methane gas supplied to the conduit.

Figure 3 shows the actual growth. Curve 1 based on circle plot
10 shows the relationship between the air ratio and the thermal Nox in the exhaust gas for a premixed flame of methane gas and air. That is, it was observed that thermal NOx was generated when the air ratio was 0.7 or higher, and it was found that the maximum amount generated was about 20 ppm. Next, a certain amount of nitric oxide g (No) is added to the premixed flame of methane gas and air, and the degree of NQxg in the exhaust gas is measured for the flame.
Here, 156 ppm ON O' was added. Therefore, the thermal NOX measured earlier and the 15
A total concentration of 6 ppm NO should be observed in the exhaust gas. That is, a curve 120 obtained by adding 156 ppm t to curve 110 should be obtained as a result of exhaust gas analysis. However, the measurement result was a curve 130 shown by a plot of square marks. In other words, this result shows that when the air ratio is 0.9 or less, the added 156pIXn
No indicates that it has been reduced to nitrogen. Therefore, it is considered that a substance that reacts with No and reduces it to nitrogen exists in a flame with an air ratio of 0.9 or less. Furthermore, the experimental results show that as the air ratio is lowered, the NOx concentration in the exhaust gas decreases more and more.

This means that the lower the air ratio of the combustion flame, the more substances that can be reduced to No. 1 are present. FIG. 4 shows the calculated value of the experimental results expressed as the ferrochemical oxide reduction rate (η) defined by the following formula. As a result of Figure 4, when the air ratio is 0.7 or less, the nitrogen oxide reduction rate η
is over 90%, and a flame with an air ratio of 0.7 or less produces a large amount of substances that reduce NO, resulting in low NO
It turns out to be very effective for X.

The present invention is based on the above experimental result 1. It is δ due to what was done in F. In other words, the generated thermal NOx is
It is a substance that reduces No, which exists in large amounts in low air ratio combustion flames, and embodies a combustion method that reduces it to harmless nitrogen.

In this experimental result, by forming a low air ratio combustion flame with an air ratio of 0.7 or less in the turbine combustor, approximately 90%
This shows that it is possible to reduce the amount of accumulated oxides on the lid. In fact, in a simulation experiment, 156 ppm of NO was added to a normal gas turbine combustor, which is almost the same as the NOx concentration in the exhaust gas without any treatment to reduce NOx. This means that the NOXIII level in the exhaust gas was reduced to 8 ppm.

[Effect between lights]

According to the present invention, the air ratio in the gas turbine combustor is 1.
It is possible to form a low air ratio combustion flame with an air ratio of less than 0 and a high air ratio combustion flame with an air ratio of 1.0 or more. generate,
Thermal NOX is generated from a high air ratio combustion flame, and the two react to form harmless nitrogen, NQxH.
It is possible to perform combustion with a small amount of .

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing an embodiment of a gas turbine combustor according to the present invention, Fig. 2 is an explanatory diagram of an experimental device for verifying the principle of the present invention, and Figs. 3 and 4 are the experimental results. FIG. 5 is a longitudinal sectional view of a conventional gas turbine combustor. 10... Low air ratio combustion flame formation nozzle, 20...
High air ratio combustion flame formation nozzle, 30.40... air bow), 50... low air ratio combustion flame, 60... high air ratio whistle 10 Kayaz'ffJ Mei 3 Prisoner 0, S O, 60 ,70,111),9/,
0 Sora Hachie Irime 4 Illustrated public notice extra inclusion

Claims (1)

[Claims] 1. A fuel injection nozzle that generates a low air ratio combustion flame is located in the center of the gas turbine combustor, and a plurality of fuel injection nozzles that generate a high air ratio combustion flame are arranged concentrically around the nozzle. a combustion flame formation method for a gas turbine, the method comprising: forming a low air ratio combustion flame and a high air ratio combustion flame in a gas turbine combustor;