JPS58187728A - Gas turbine combustor - Google Patents

Abstract

PURPOSE:To reduce NOX by injecting small amount of water by providing an inner cylinder formed of a premixture combustion chamber which has a combustion nozzle, a swirler and an air hole formed at the periphery and a water injection unit at the rear flow section and a rear combustion chamber in an outer cylinder. CONSTITUTION:An inner cylinder 29 formed of a premixture chamber 31 and a rear combustion chamber 32 of a diameter larger than that of the chamber 31 is provided in an outer cylinder 28. A fuel nozzle 36 is provided at the side inner end of the chamber 31, a swirler 33 and an air hole 34 are formed on the outer periphery, and a water injection nozzle 43 is provided at the rear flow section of the chamber 31. Fuel 24 introduced from the fuel nozzle 36 is mixed with air streams 25-27 from the swirler 33 and the air hole 34, and low temperature combustion is continued. Since NOX is produced due to main flame 42 in the step of burning, NOX reducing effect can be raised with less amount of water by performing the uniformly cooling of the flame with the water 44.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lean low-temperature combustor that uses natural gas or the like as fuel, and more particularly to a gas turbine combustor that aims to reduce nitrogen oxides (hereinafter referred to as NOx).

In gas turbines, NO contained in the exhaust gas
x , -Unburned components such as carbon oxide (hereinafter referred to as CO) and hydrocarbons (hereinafter referred to as HC) are air pollutants, and reducing these emissions is equivalent to or better than improving performance and reliability. This is important. Especially in areas near ants, NOx emission regulations are strict, and the current combustor emission concentration must be reduced to 1/10 or less. NOx is generated in the combustor, and it is conceivable to install an after-treatment device such as a denitrification device to remove it. However, the installation of a denitrification device has drawbacks such as an increase in operating costs due to the use of a large amount of denitrification catalyst and its deterioration, and an increase in exhaust pressure in the exhaust duct, which deteriorates the performance of the K-yield turbine. So N.O.
The best way is to reduce NOx in the combustor, which is the source of x+CO. To suppress the production of NOx, the temperature of the combustion flame must be effectively lowered).
The key to reducing NOx is how to effectively cool the high-temperature flame. As a specific example, it is common practice to directly cool a high-temperature flame by adding water, steam, etc. to the high-temperature combustion section. However, adding water and steam reduces turbine efficiency, requires a large amount of water and steam supply sources, and even if a large amount of water is added, it is not possible to uniformly cool a high-temperature flame, making it difficult to significantly reduce NOx. I can't. Moreover, it has the disadvantage that it cannot achieve a satisfactory NOx reduction in the recent severe environmental gLIIill values. Another specific method for cooling a high-temperature flame is to reduce NOx by supplying a large amount of dilution air, which is unique to gas turbines, to the combustion section to perform so-called lean low-temperature combustion to keep the flame temperature low.

However, because the air and fuel cannot be mixed uniformly and the high-temperature flame cannot be effectively cooled, the NO reduction is smaller than with water or steam injection, and even when water injection is used in combination, uniformly mixed combustion and its uniform cooling cannot be achieved. A wide N that requires rounding that cannot be done.
Ox reduction is not possible.

FIG. 1 shows nine conventional technologies that are combined with water injection technology.

The gas turbine includes a pressure m1a1, a turbine 2, a combustor 3, and a load section (such as a generator), although not shown. The combustor 3 has an inner cylinder 4 and Ij! , i15', a cover 7 is attached to the side closed end of the outer tube 6, and a fuel nozzle 8 and a water injection nozzle 9 are attached to the cover 7. A tip 10 of the fuel nozzle 8 is attached to a side end (liner cap) 11 of the inner cylinder 4 . Also, the tip of the water injection nozzle 9 is a liner cap 11.
The combustion air 12 is located in the space between the liner cap and the cover 7, and is injected into the combustion air 12 outside the liner cap and introduced into the inner cylinder 4. Compressor 1
The compressed air 13 flows to cover the transition piece 5, passes through the annular space 14 between the outer cylinder 6 and the inner cylinder 4, and enters the air hole 15 closed to the inner cylinder 4, the dilution air hole 16, and the inner cylinder 4. Air hole 17 for surface cooling, swath 9 attached to liner cap 11
18 into the inner cylinder 4. The fuel 19 supplied from the combustion nozzle 8 mixes with the combustion air 20m, 20b to form a high temperature flame 21. Since NOx is generated in this high temperature section, in order to suppress this, water is injected from the water injection nozzle 9 toward the swirler 18 and mixed with the air flow 20a, thereby cooling the high temperature flame section 21 and reducing NOx. There is. Combustion flame 21d is further mixed with air 20C, cooling air 20b, and dilution air 23 to become combustion gases 22M and 22b, which are guided to the turbine 2.

However, the fuel 19 is in the swirler 1 having multiple swirl grooves.
The combustion flame 21 that sustains combustion is formed while diffusing and mixing with the swirling air 201 from 8 and the combustion air 20b introduced from a plurality of air holes, but in the process of diffusion heating, the fuel 1
9 and air flowing in from the multiple groove swirler and multiple air holes 2
0m, 20b in the combustion flame because uniform mixing with 20b is not possible.
In No. 1, fuel-rich and air-rich areas are locally formed.

Because of this, a high temperature combustion part is created and NO! It is a major cause of generation. Therefore, in the conventional water injection technology that injects water or steam 50 into the combustion flame 21 to reduce NOx, the non-uniform combustion flame 21 is uniformly cooled, and NO
It is not possible to uniformly cool only the high temperature flame generated by x, making it impossible to efficiently reduce NOx. Furthermore, the action of supplying water 51 to the air-rich region has the disadvantage that unburned components such as CO and HC are generated which inhibit combustion. For this reason, approximately 5
The water injection flow rate to achieve a total NOx reduction of 0 to 60 - requires a weight ratio of approximately 1 or more to the total air flow rate to the combustor, and even if the water injection flow rate is increased beyond this, it will not be possible to achieve a large reduction in NOx. It cannot reduce NOx, and has the major drawbacks of rapidly increasing unburned phosphorus such as Co and HC, and reducing turbine efficiency.

An object of the present invention is to provide a gas turbine combustor that achieves a significant reduction in NOx with a small amount of water or steam injection.

The features of the gas turbine combustor that achieve the objectives of the present invention are:
An inner cylinder is provided inside the outer cylinder, and the inner cylinder is formed of a premix combustion chamber and a rear combustion chamber having a larger diameter than the premix combustion chamber,
A fuel nozzle is provided at the inner end of the premix combustion chamber, and a swirler and an air hole for uniformly mixing fuel and air are provided on the outer periphery of the fuel nozzle, and a fuel nozzle is provided near the wall flow section of the premix combustion chamber. The reason is that a device for injecting water or steam is provided inside the device.

An embodiment of the present invention will be explained in detail with reference to FIG.

First, in order to uniformly mix the fuel 24 and the air 25, 26, 27 and achieve uniform combustion,
The inner cylinder 29 is provided with a premix combustion chamber 311 at the head!
- The premix combustion chamber 31 is formed to have a smaller diameter than the rear combustion chamber 32 for promoting uniform mixing of the fuel 24' and air. A swirler 3B for introducing swirling air is provided around the nozzle 36, and a swirler 33, an air hole 34, and scoop air holes 34m and 34b are provided outside of the swirler 3B.

The amount of air introduced into the premix combustion chamber 31 is about 1.5 times that of a conventional combustor that does not perform low NOx, and is based on lean low-temperature combustion that achieves uniform mixing, and the flame is premixed combustion. It is formed from the chamber 31 to the rear combustion chamber 32. The fuel 24 introduced from the fuel nozzle 36 passes through the swirler 38
, swirler 33 and scoop 34a, 34bs air hole 3
It mixes with the air flow 25.37, 35, 26.27 from 4 and swirls 38 near the low temperature 36! Circulation induced by 33! j! The airflow from the flow 39 and the scoops 34a, 34b increases turbulence within the combustor, resulting in better mixing of fuel and air in the premixing chamber 31. There are a stable flame 40 formed by the circulation flow 39 at the axial center of the premix combustion chamber 31 and a main flame 42 formed from the downstream side 41 of the premix combustion chamber 31 to the rear combustion chamber 32. The flame 40 has a flame-holding function that affects the stability of the combustor, and the main flame 42 performs lean, low-temperature combustion of premixed fuel, resulting in a uniform combustion flame. The flame generated by this main flame 42 is dominant. Therefore, in order to further reduce NOx, effectively and uniformly cooling this flame is the best way to achieve a very large reduction in NOx. That is, unlike the prior art, in the present invention, the turbulent diffusion mixing of the fuel 24' and the air 37, 25, 26, 27 is improved in the premix combustion chamber 31, so there is less localized high-temperature combustion, and the system is Therefore, combustion that suppresses the generation of NOx can be performed. Furthermore, the premix combustion chamber downstream 41
A water injection nozzle 43 is located between the rear combustion chamber 32 and the rear combustion chamber 32.
By installing a main flame 42 and cooling the main flame 42 with water, it is possible to achieve very uniform cooling of the flame, which has not been seen with conventional technology.
Ox can be reduced. That is, a water injection nozzle 43 is installed to supply water into the combustion air flow 27 from a plurality of air ports 34b opened at the rear side of the premix combustion chamber 31, and water is not mixed into the combustion air flow 27. It is supplied to the rear side of the premix combustion chamber 31. The sprayed water 44 does not affect the stable flame 40 formed at the head of the premix combustion chamber 31, and can effectively cool the main flame 42 that controls the generation of NOx. It is possible to obtain a large NOx reduction effect with a small amount of water.

FIG. 3 shows an example of the results of a combustion test in which the water injection technology of the present invention was applied to a 70 MW class gas turbine combustor. In this figure, the horizontal axis shows the fuel-air ratio (the weight ratio between the fuel flow rate and the air flow rate, which corresponds to the turbine load), and the vertical axis shows the experimental values of the NOx concentration. These are the test results when the combustor pressure was 4 atmospheres. Turbine load 100
In terms of high-temperature equivalents, the conventional combustor No. 1 shown in Figure 1
In the water injection technology of a combustor that uses a premixed combustion chamber for xa degrees, the water injection flow rate can reduce NOx by approximately 801 at α51 in weight ratio to the total combustion air fi amount. It is possible to reduce NOx, which cannot be achieved with injection technology, and the amount of water injection is 1/1 compared to conventional technology.
This means that it can be reduced to 4 or less. However, 0
．． When the water injection technology of Section 5 is applied to gas turbine operation, when the turbine load is approximately 100 liters, a blowout phenomenon occurs in which combustion cannot continue due to overcooling of the flame by water. Therefore, as an example of one control during turbine operation, approximately 60-
By operating without water injection until the turbine is loaded, and then injecting water at a rate of 0.5 when the load reaches 60°, approximately 80-N is generated when the load is at 9100°.
This makes it possible to reduce Ox. Therefore, N O
The x concentration means that the NOx concentration changes from person to A1, then to A at a turbine load of 60 degrees, to B0, and then to B at a turbine load of 100 degrees.

FIG. 4 shows another embodiment of the water injection section.

The scoop hole 34b protrudes into the combustor, and the combustor inner cylinder 29
It has the effect of breaking the 45 layers of air flowing along the inner surface of the shaft and improving air penetration to the inside (axis center).
The inner surface protruding portion 34b' comes into contact with the flame and is heated to a high temperature. Although deterioration of this rounded scoop hole 34b occurs, the fourth
As shown in the figure, the water injection nozzle 43 is provided with a plurality of injection ports at its tip, and one portion of the water injection #146 is supplied so as to be along the inner surface 47 of the scoop hole 34b, thereby cooling the scoop hole 34b. Scoop hole 3 to contribute to lower NOx
It is a water injection structure that also improves the reliability of 4b.

As described above, according to the present invention, by combining a lean low-temperature combustor and an optimal water injection technology, it is possible to obtain a significant reduction in Not compared to a conventional combustor. The same level of NO! In order to achieve the reduction rate, the present invention has the great effect of reducing the water injection amount to about 1/4 or less.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a conventional gas turbine combustor, FIG. 2 is a longitudinal sectional view of a gas turbine combustor showing an embodiment of the present invention, and FIG. 3 is a longitudinal sectional view showing a combustor of the present invention and a conventional combustor. N with
Graph Comparing Ox Amounts FIG. 4 is a longitudinal sectional view showing another embodiment of the water injection part of the present invention. 24... Fuel, 25-27... Air, 28... Outer cylinder, 29... Inner cylinder, 31... Premix combustion chamber, 32...
...Rear combustion chamber, 33...Swirl device, 34...φ hole, 34a. 34 b...

Claims (1)

[Claims] 1. An inner cylinder is provided inside the outer cylinder, and the inner cylinder is formed of a premix combustion chamber and a rear combustion chamber having a larger diameter than the premix combustion chamber, and A fuel nozzle is provided at the side end of the #! A swirler and an air hole are provided for uniformly mixing the first fuel and air, and a device for injecting water or steam into the premix combustion chamber is provided near the downstream part of the premix combustion chamber. Gas turbine fuel i11ags02, in claim 1, a part of the air holes is formed as a scoop hole that projects inside, and a nozzle for injecting water or steam is provided in the scoop hole. A gas turbine combustor featuring: 3. The gas turbine combustor according to claim 2, characterized in that the nozzle is provided with a hole so that a portion of the water or steam injected from the nozzle collides with the inner wall surface of the scoop hole. .