JPS602827A - Combustor of gas turbine - Google Patents

Abstract

PURPOSE:To finely atomize and homogeneously blend the fuel for combustion for thereby lowering NOx emissions, by providing a primary air feeding swirler at the inlet of premixing channel in front of a combustion chamber and providing the front face of swirler with a fuel feeding pipe having its injection ports faced to respective blades of swirler. CONSTITUTION:A primary air A is caused a swirling movement by means of blade 16 in passing through a swirler 15. A liquid fuel is injected in an atomized state through fuel injection ports 18 defined in a fuel feeding pipe 17 arranged in front of a swirler 15. The fuel is then finely atomized in contact with a high- speed air stream passing through blades 16, an collides with blades 16 for further atomizing. Since the number of fuel injection ports 18 is equal to that of blades 16, the fuel is uniformly injected over the entire air stream which passes through the swirler 15, and can be thus homogeneously blended. The fuel is thus finely atomized and homogeneously blended at the inlet of premixing channel 10 and therefore can be evaporated and homogeneously blended inside the premixing channel in an extremely short period. In consequence, NOx emissions can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas turbine combustor, and more particularly to a combustor equipped with a fuel atomization device.

As is well known, in order to improve the performance of a gas turbine, the pressure ratio in the combustor is increased. However, if the secondary air is made to have a high pressure, the flame temperature within the combustor will increase, and the concentration of nitrogen oxides (NOx) in the exhaust gas will increase, causing pollution.

That is, N from gas turbines and jet engines
Ox emissions are highly dependent on the combustor flame temperature of those engines. The flame temperature also depends on the combustor inlet temperature. This indicates that the amount of NOx emissions increases as the compressor pressure ratio increases. Apart from this, even at low pressure ratios, N
Ox emissions increase.

For this reason, in the conventional method, water was injected into the combustor to lower the flame temperature and attempt to achieve low NOx. This method is currently the most reliable and quickest method and is widely used in industrial applications.

However, the water injection type is more expensive than the dry type in terms of incidental equipment such as a water purifier and running costs. In addition, it is difficult to employ it in mobile turbines for transportation systems and the like.

Note that the above NOx emissions do not depend on the average combustion temperature in the combustor, but are affected by the maximum temperature, and are determined by the conventional equivalence ratio (the ratio of the actual mixture ratio to the theoretical fuel-air mixture ratio). In a high-load combustor with a large
This maximum temperature resulted in an increase in NOx emissions.

With the above-mentioned conventional technology as a background, research has recently been underway to achieve low NOx in a dry manner by pre-evaporating liquid fuel, uniformly mixing it with air, and then combusting it. According to this, the current amount of NOx emissions during aircraft cruising is included. decrease to.

This combustion method is the pre-evaporation/premix combustion method (Lean).

Premixed, Prevaporized! u
el combustion) and is a lean burn method. In this combustion method, the amount that ultimately flows into the main combustion zone is approximately half of the stoichiometric mixture ratio of fuel and air < (0,55
~0.6), and aim to achieve a NOx level of 0.6%.

However, the above pre-evaporation/premix combustion method (L, P, P, )
In this case, the problem is how to evaporate the fuel in a short time and mix it uniformly with the combustion air.

That is, in the above LPP, as shown in Fig. 1 7), a preevaporation/premixing passage (2) is provided at the front of the combustion chamber (1), and ultra-lean mixing is performed within this passage (2). However, if the fuel is not evaporated in a short time and mixed uniformly in the passage (2), spontaneous ignition and backfire will occur in the passage (2), making it difficult to reduce NOx emissions. It cannot be done.

This is confirmed from the measured data and calculated data shown in FIGS. 2 to 5.

FIG. 2 shows the relationship between flame temperature and NOxOx emissions, and shows that the higher the flame temperature, the greater the NOx amount.

FIG. 3 shows the relationship between the residence time of the mixed fuel in the mixing passage (2) and the NOx emission amount, and shows that the longer the residence time or the larger the equivalence ratio, the greater the NOx amount.

Figure 4 shows the relationship between pressure, ignition delay time, and fuel evaporation time. When the pressure is constant, the ignition delay time is also constant, and it shows that the finer the fuel particles are, the better to quickly evaporate within this ignition delay time. ing. In other words, if the ignition delay time is exceeded, the fuel will spontaneously ignite, so if the evaporation is not completed within the ignition delay time, the fuel will not burn out. , indicating that the fuel particles must be fine.

Figure 5 shows the relationship between equivalence ratio and NOx,
In the case of homogeneous mixing, the amount of NOx decreases with dilute mixing, but with non-uniform mixing, the amount of NOx increases regardless of the mixing ratio.

To summarize the above, the combustion method that achieves homogeneous mixing in an ultra-dilute and short time and completes combustion in a short time is the best way to achieve low NO
This means that x can be achieved. By performing pre-evaporation and pre-mixing in a short time, spontaneous ignition and backfire can be prevented.

As detailed above, in LPP, it is recognized that the initial particle size of the fuel must be made small in order to mix the fuel and fuel air and evaporate the fuel in a short time. However, the means to achieve this goal is still unresolved. That is, conventionally, as shown in Fig. 1, fuel was injected from a single or a small number of nozzles (6) to the air after passing through the secondary air supply swirler (4). , atomization and homogeneous mixing of fuel were different.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a gas turbine combustor that can refine and homogeneously mix fuel with an extremely simple structure.

Therefore, its characteristics are that a premixing passage communicating with the combustion chamber is provided at the front part of the combustion chamber, a swirler for supplying primary air is provided at the entrance of the passage, and each blade of the swirler is provided with fuel. A fuel supply pipe having an ejection hole facing each blade is disposed on the front surface of the swirler so that the fuel directly collides with the swirler.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

What is shown in FIGS. 6 to 8 is an embodiment of the present invention.

In the figure, a gas turbine combustor (6) includes a cylindrical outer casing (8) whose opening at one end serves as a high-pressure air intake port (7) from a compressor (not shown), and an inner surface of the casing (8). A combustion chamber (9) is fitted concentrically within the combustion chamber (9) with a predetermined gap, and a combustion chamber (9) protrudes forward from the front wall of the combustion chamber (9) within the outer casing (8) concentrically with the combustion chamber (9). It has a cylindrical pre-evaporation and pre-mixing passageway (10).

The rear end of the combustion chamber (9) is a high-temperature, high-pressure combustion gas exhaust port (ol).
The outer peripheral surface of the exhaust port (11) is connected to the outer casing (
8) is internally fitted and fixed to the inner surface of the rear end. Combustion gas from the exhaust port (■l is introduced into the turbine (not shown). The combustion chamber (
A plurality of dilution ports 02) are provided on the rear peripheral wall surface of 9).

In the center of the front end surface of the combustion chamber (9), there is a premixing passage (lO).
A conical flame stabilizer Q3i protruding inward is provided concentrically with the passageway (lO). A premixing passage (lO
) and the combustion chamber (9) are provided with an annular inlet 04).

A primary air supply swirler (15) is provided at the front end entrance of the premixing passage (10). As shown in FIGS. 7 and 8, the swirler θ is provided with a large number of radial fixed vanes (16N) having a predetermined helix angle. θ6
), the air is given a swirling motion and introduced into the premixing passage +101.

A fuel supply pipe (Iη) is provided in front of this swirler (I5). This combustion supply pipe a″iI is connected to the swirler (1
The supply pipe Q71 is an annular pipe located approximately on the central circumference between the inner and outer circumferences of the supply pipe Q71, and a large number of small-diameter combustion ejection holes α8) are provided in the end face of the supply pipe Q71. The nozzle holes are provided facing each vane (16) so that the combustion of the nozzle shells directly collides with the blades 00.

According to the embodiment of the present invention, the high pressure air from the compressor passes through the high pressure air intake port (7), and a part of it passes through the swirler αm.
1 and enters the preevaporation/premixing passage (river).

In addition, a part of the high-pressure air passes through the gap between the outer circumferential surface of the premixing passage (10), the outer circumferential surface of the combustion chamber (9), and the inner circumferential surface of the outer casing (8), and passes through the dilution port at the rear of the combustion chamber (9). (Enter the combustion chamber (9) from +21.

The high-pressure air passing through the swirler (15) is given swirling motion by the blades (16) of the swirler (Iω).

The swirler (15)
(15) Liquid fuel is injected from the fuel injection hole θ of the fuel supply pipe (lη) arranged on the front side.The fuel injection method is pressure spray type, airplast type, or air assist type. You can.

The fuel injected from the fuel injection hole (I8) becomes a spray and is ejected from the injection hole 08), and is further atomized by the high-speed airflow passing between the blades (16) of the swirler-θ, and The fuel particles collide with the vanes (16), further promoting atomization and achieving homogeneous mixing.

The above-mentioned fuel sting ejection hole weights are provided in the same number corresponding to the number of swirler blades α6) of the swirler θω.
), and the injected fuel is uniformly injected over the entire air passing through the swirler (+51), contributing to homogeneous mixing.Furthermore, the fuel collides with the blade (I6). By doing so, atomization of the fuel is promoted.

The atomized fuel is then transferred to the pre-evaporation/pre-mixing passage (1
0), the mixture evaporates and is further homogeneously mixed.

Since the fuel is atomized and uniformly mixed at the inlet of the premixing passage (10), it evaporates and is homogeneously mixed within the premixing passage (10) in a very short time.

Therefore, there is no risk of spontaneous ignition within the premixing passage (lO). Further, there is no possibility that the flame in the combustion chamber (9) will backfire.

The pre-evaporated and pre-mixed fuel and air are transferred to the combustion chamber (9).
It enters the combustion chamber (9) from the front inlet port (04), burns in the combustion chamber (9), becomes high-temperature, high-pressure gas, and exits the exhaust port (11).
) is ejected at high speed.

The mixed gas passing through the introduction port (14) is
3) gives a swirling motion, and the gas mixture moves into the combustion chamber (
9) The flame will move in a swirling motion at the front.

This thin layer will hold the flame and prevent it from blowing out.

According to this embodiment, homogeneous pre-evaporation and pre-mixing can be achieved in a short period of time, and the low N
It is possible to achieve Ox conversion.

Note that the present invention is not limited to the above embodiments.

According to the present invention, since the fuel can be made fine and homogeneously mixed and then combusted, the number of NOx emissions can be reduced.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional combustor, Figure 2 is a graph showing the relationship between flame temperature and NOx amount, Figure 3 is a graph showing the relationship between residence time and NOx amount, and Figure 4 is a graph showing the relationship between pressure and NOx amount. FIG. 5 is a graph showing the relationship between spontaneous ignition time and evaporation time, FIG. 5 is a graph showing the relationship between equivalence ratio and NOx amount, and FIG.
FIG. 7 is a cross-sectional view of the swirler, and FIG. 8 is a front view of the swirler. (6)...Combustor, (9)...Combustion chamber, (10)...
...Premixing passage, 0 (to)...Swirler-106)...
- Vane, θ force...Fuel supply pipe, α8)...Blowout hole.

Claims (1)

[Claims] 1. A premixing passage communicating with the combustion chamber is provided at the front of the combustion chamber, and a swirler for supplying primary air is provided at the entrance of the passage, and each blade of the swirler is provided with a swirler to directly impinge fuel on each blade. A gas turbine combustor characterized in that a fuel supply pipe having facing jet holes is disposed in front of a swirler.