JP2000314526A - Pre-evaporation/premixing burner and premixing burner for gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a strong recirculation flow by providing a tubular pipe outlet with a throttling part and an enlarged part continuous thereto, thereby spreading mixture gas delivered from a pre-evaporating/premixing burner or a premixing burner. SOLUTION: A tubular pre-evaporating pipe L1 is provided, at the outlet thereof, with a throttling part 4b and an enlarged part 4c continuous thereto. With the assistance of action from a swirling air flow from a swirler 3, a mixture gas exhausted from the pipe L1 into a combustor 6 is spread into skirt shape and a recirculation flow 8 returning toward the center is formed. The flame is thereby held in the recirculation flow 8 and mixed well with combustion gas of a pilot burner, thus completing combustion within a short distance. Consequently, high combustion efficiency can be attained, even if firing performance is deteriorated due to high air/fuel ratio resulting in low NOx combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a combustor of a gas turbine, in particular order to lean pre-vaporization Hatsu予mixing or stabilizing the combustion efficiency of the flame of the premixed combustion method for reducing NO _x reduction combustion A pre-evaporation pre-mix burner or a pre-mix burner for a gas turbine combustor.

[0002]

2. Description of the Related Art Gas turbine combustors are roughly classified into a can type and an annular type. The can type includes a type in which a plurality of independent cylindrical combustors are arranged at equal intervals on the same circumference, and a type in which a single cylinder combustor is used. The annular type is a donut-shaped integral combustor having a combustor outer case, a combustion chamber, and a combustor inner case.

[0003] The gas turbine combustor must have high combustion efficiency, low pressure loss, high combustion load factor, small size and light weight, and stable combustion without blow-out. it, it exit temperature distribution is uniform, it is like emission of air pollutants such as NO _X is small. The annular type is excellent in that the structure of the combustor is simple and small, and the outlet temperature distribution is uniform.

When kerosene is used as gas turbine fuel, the stoichiometric air-fuel ratio (weight ratio) required for burning kerosene is about 1%.
5: 1. When the primary combustion is performed at this air-fuel ratio, the flame temperature reaches 2000 ° C., and a large amount of NO _X is generated. In recent years, lean combustion methods have been adopted in land-based gas turbines and the like in order to reduce the amount of NO _X generated by lowering the flame temperature.

When a liquid fuel such as kerosene is used as a fuel, a lean pre-evaporation premix combustion method is used, and when a gaseous fuel such as methane is used, a lean premix combustion method is used.

FIG. 3 is a sectional view of an annular type combustor provided with a pre-evaporation pre-mix burner, FIG. 4 is a cross-sectional view of the pre-evaporation pre-mix burner, and FIG. 5 is a cross-sectional view of the pre-mix burner. In these figures, L is a pre-evaporation premix burner or a premix burner. L ₁ is a pre-vaporization Hatsu予mixing burner, L ₂ is a premixing burner. Pre-evaporation pre-mix burner L
₁ has a liquid fuel nozzle 1. 1a is an outer cylinder of the nozzle, 1b is an inner cylinder of the nozzle, 1c is a space formed between the outer cylinder and the inner cylinder, and is connected to a fuel supply pipe 1f. Reference numeral 1d denotes a slit formed at the tip of the outer cylinder 1a and the inner cylinder 1b, and ejects liquid fuel into an annular thin film. 1e is an air passage formed inside the inner cylinder 1b. Reference numeral 3 denotes a swirler surrounding the liquid fuel nozzle 1, which swirls the passing air to cause an appropriate turbulence in the air flow,
The inflow velocity is reduced and the flame propagation velocity is increased. 4
Is a cylindrical body in which the swirler 3 is fitted, and the downstream side is connected to the annular type combustor 6. 5 is a flange. The thin-film liquid fuel ejected from the nozzle 1 is subjected to a shearing force due to the difference between the flow velocity of the swirling air flow from the swirler 3 and the flow velocity of the inner air flow, becomes mist-like fine particles, and evaporates quickly. The annular type combustor 6 has an annular outer liner 6a and an inner liner 6b.
And the outer liner 6a
A combustion chamber 6c is formed between the fuel cell and the inner liner 6b. The upstream side of the combustion chamber 1c is closed by an annular disc 6d, and a pre-evaporation premix burner or a premix burner L is connected to the disc 6d. Outer liner 6a, inner liner 6b
Is formed of a thin plate having a number of holes, and the outside air flows into the combustion chamber and flows along the inner surface of the liner to cool the wall surface. Reference numeral 7 denotes a flame formed on the downstream side of the pre-evaporation tube.

[0007] premixed burner L ₂ has a gaseous fuel nozzle 2 as shown in FIG. The gaseous fuel nozzle 2 has a cylindrical shape having a space 2a, and a fuel supply pipe 2c is connected to the space 2a. Reference numeral 2b denotes a fine hole connected to the downstream end of the space 2a and a fine hole opening on the circumferential surface, and a large number of fine holes are formed in the circumferential direction.

FIG. 6 is a diagram showing a mounting arrangement of a pre-evaporation pre-mix burner or a pre-mix burner L to the annular type combustor 6.
FIG. 7 is a mounting layout of the pre-evaporation pre-mix burner or the pre-mix burner L to the can-type combustor 7. In the figure, P is a pilot burner for holding a flame. In the annular type combustor 6, one pilot burner P may be arranged for two pre-evaporation pre-mixing burners or two pre-mixing burners L as shown in FIG. May be. In the can type combustor 7, a plurality of pre-evaporation premix burners or premix burners L are arranged around one pilot burner P.

The lean pre-evaporation premix combustion method or the lean pre-mix combustion method has a pre-evaporation pre-mix burner or pre-mix burner L having such a structure, and burns the air-fuel ratio to 45 or more in a lean fuel state. This is a combustion method in which the amount of generated NO _X is reduced to about 1/10 of a normal level by keeping the fire temperature at 1600 ° C. or lower.

[0010]

As described above, the lean pre-evaporation premixed combustion method or the lean pre-mixed combustion method requires a pilot burner in order for the lean pre-evaporation pre-mixed gas or the lean pre-mixed gas to ignite and burn. , A pre-evaporation pre-mixing burner or a pre-mixing burner must be arranged in order to mix well with the combustion gas of the pilot burner, and the progress of combustion is limited by the mixing speed. However, since the conventional pre-evaporation pre-mix burner or pre-mix burner has a cylindrical shape, even if there is a swirling flow due to the swirler, the air-fuel mixture from the pre-evaporation pre-mix burner or pre-mix burner is discharged after leaving the pipe. Since the spread is small and the recirculation flow is weak, the flame becomes a substantially cylindrical flame as shown in FIG. Therefore, mixing with the combustion gas of the pilot burner is not good, and a long combustion distance is required. If the air-fuel ratio is increased, ignition is difficult to occur, and the combustion efficiency is reduced.

The present invention has been devised in view of such a problem of a conventional pre-evaporation premix burner or a premix burner.
It is an object of the present invention to provide a pre-evaporation pre-mix burner or a pre-mix burner for a gas turbine combustor in which the spread of the air-fuel mixture exiting the pre-evaporation pre-mix burner or the pre-mix burner is increased to generate a strong recirculation flow. I do.

[0012]

According to a first aspect of the present invention, there is provided a pre-evaporation premix burner for a gas turbine combustor having a swirler surrounding a fuel nozzle on an upstream side and a combustion chamber on a downstream side. A pre-evaporation pre-mixing burner having a cylindrical tube connected to a vessel, pre-evaporating liquid fuel, pre-mixing with air, and blowing into a combustor, wherein the pre-evaporation pre-mixing burner is connected to the outlet of the cylindrical tube and connected thereto. A divergent portion is provided.

According to a second aspect of the present invention, there is provided a premix burner for a gas turbine combustor having a swirler surrounding a fuel nozzle on an upstream side and a downstream side connected to a combustor for premixing gaseous fuel with air for combustion. What is claimed is: 1. A premixing burner having a cylindrical tube blown into a vessel, wherein a narrowed portion and a divergent portion connected to the narrowed portion are provided at an outlet of the cylindrical tube.

It is preferable that the reduction rate of the diameter of the narrowed portion is 15 to 30%, and the spread angle of the divergent portion is 20 to 45 °. In particular, it is most preferable that the reduction rate of the diameter of the narrowed portion is 20% and the spread angle is 25 °.

Next, the operation of the present invention will be described. Since a narrowed portion and a divergent portion connected to it are provided at the outlet of the cylindrical tube, the air-fuel mixture discharged into the combustor from the tube spreads in a skirt shape with the help of the swirling air flow from the swirler,
The divergent stream forms a recirculating stream returning back to the center. The flame is held in the recirculation flow, and the mixing with the combustion gas of the pilot burner becomes good, and the combustion is completed in a short distance. Thus, high to the air-fuel ratio ignitability is deteriorated can be obtained even higher combustion efficiency, it is possible to achieve low NO _X combustion.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a pre-evaporation pre-mixing burner of a gas turbine combustor according to the first aspect of the present invention. In this drawing, the same reference numerals are given to the same parts as those described with reference to FIGS. 3 to 5 as the related art, and the overlapping description will be omitted.

The cylindrical pre-evaporation pre-mixing burner L ₁ has a liquid fuel nozzle 1 on the upstream side.
And a swirler 3 is provided. Downstream of the pre-vaporization Hatsu予mixed burners L ₁ is connected to the combustor 6, the liquid fuel issuing pre-vaporization, is blown into the combustor 6 are mixed air and pre. The fuel ejected from the slit 1d of the liquid fuel nozzle 1 as an annular thin film is subjected to a shearing force by the air flow from the air passage 1e of the nozzle 1 and the swirling air flow from the swirler 3, and rapidly becomes mist-like fine particles. Evaporate. Pre-evaporation pre-mix burner L
The downstream side of the cylindrical body 4a is connected to the combustor 6, and a narrowed portion 4b and a divergent portion 4c connected to the narrowed portion 4b are provided inside the outlet of the cylindrical body 4a. The reduction rate β of the diameter of the narrowed portion is expressed by the following equation. β = (D ₁ −D ₂ ) / D _{1 The} reduction rate can be set to 15 to 30%.
% Is preferable.

The divergent angle α of the divergent portion 4c is 20 to 45.
The angle can be ゜, but about 25 特 に is particularly preferable.

The air-fuel mixture discharged from the pre-evaporation pre-mixing burner L1 spreads in a skirt shape while maintaining the spread angle α as shown in FIG. 1, and the spread flow forms a recirculating flow 8 returning to the center again. Form.

Next, the operation of the present embodiment will be described. A cylindrical pre-vaporization Hatsukan L ₁ of the outlet to the throttle portion 4b, is provided with the flared portion 4c which is connected to it, also helped by the action of revolving airflow from swirler 3, the combustor 6 from the pipe L ₁ The discharged air-fuel mixture spreads in a skirt, and the expanded flow forms a recirculating flow 8 returning to the center again. The flame is held in the recirculating flow 8 and is mixed with the combustion gas of the pilot burner P. And the combustion is completed in a short distance. Thus, high to the air-fuel ratio ignitability is deteriorated can be obtained even higher combustion efficiency, it is possible to achieve low NO _X combustion.

In order to confirm the effectiveness of the present invention, a comparative test was conducted between a conventional pre-evaporation / pre-mixing tube and the pre-evaporation / pre-mix burner of the present invention. FIG. 2 is a comparison graph of the test results. In the figure, a straight type is a conventional pre-evaporation pre-mixing burner, and a throttle widening type is a pre-evaporation pre-mixing burner of the present invention. The combustion efficiency is a ratio between an increase in the enthalpy (or temperature) of the inflow air and the amount of supplied heat. The combustion efficiency η is given by the following equation. _{η = {(W a + W} f) i b - (W a · i a + W f · i
_f)} / W _f · H where H: lower heating value of the fuel (kcal / kg) W _a: inlet air flow rate (kg / s) W _f: fuel flow (kg / s) i _b: enthalpy of the combustion gas (kcal / kg) i _a: enthalpy of the incoming air (kcal / kg) i _f: fuel enthalpy (kcal / kg) also, the air-fuel ratio [delta] is δ = W _a / W _f.

Generally, the combustion efficiency is required to be 99% or more in practical use. Therefore, it is difficult for the conventional pre-evaporation pre-mixing burner to have an air-fuel ratio of more than 45, but in the present invention, it is up to about 65. It is possible to rise.

The present invention is not limited to the embodiment described above, and various changes can be made without departing from the gist of the invention. In the description of the embodiment, claim 1
The pre-evaporation pre-mixing burner of the gas turbine combustor according to the described invention has been described. However, the pre-mixing burner is different only in the shape of the fuel nozzle, and the gas fuel nozzle has already been described with reference to FIG. Therefore, description of the premix burner of the gas turbine combustor according to the second aspect of the present invention will be omitted.

[0024]

As described above, the pre-evaporation pre-mixing burner or pre-mixing burner of the gas turbine combustor according to the present invention comprises:
Since the outlet of the pipe has a constricted part and a divergent part connected to it, the air-fuel mixture discharged from the pipe is helped by the swirling air flow from the swirler and spreads in a skirt shape. To form a strong recirculating flow returning to The flame is held in the recirculation flow, and the mixing with the combustion gas of the pilot burner becomes good, and the combustion is completed in a short distance. Therefore, an excellent effect, such as high in the air-fuel ratio ignitability is deteriorated can be obtained even with high combustion efficiency, it is possible to achieve low NO _x combustion.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pre-evaporation pre-mix burner of a gas turbine combustor according to the present invention.

FIG. 2 is a graph of a performance comparison between a pre-evaporation pre-mixing burner of the present invention and a prior art, showing a relationship between an air-fuel ratio and combustion efficiency.

FIG. 3 is a sectional view of a conventional annular type combustor equipped with a pre-evaporation pre-mixing burner.

FIG. 4 is a cross-sectional view of a conventional pre-evaporation pre-mix burner.

FIG. 5 is a sectional view of a conventional premix burner.

FIG. 6 is an installation layout of a pre-evaporation pre-mix burner or a pre-mix burner to an annular type combustor.

FIG. 7 is a mounting layout of a pre-evaporation pre-mixing burner or a pre-mixing burner to a can-type combustor.

Claims (4)

[Claims] An upstream side has a swirler surrounding a fuel nozzle, and a downstream side is connected to a combustor, and has a cylindrical pipe for pre-evaporating liquid fuel, premixing with air and blowing into a combustor. A pre-evaporation premix burner for a gas turbine combustor, wherein a pre-evaporation burner is provided with a throttle portion and a flared portion connected to the throttle portion at the cylindrical pipe outlet. 2. A premixing pipe having a swirler surrounding the fuel nozzle on an upstream side and a cylindrical pipe connected to a combustor on the downstream side and premixing gaseous fuel with air and blowing the gaseous fuel into the combustor. A premix burner for a gas turbine combustor, wherein a narrowed portion and a divergent portion connected to the narrowed portion are provided at the cylindrical pipe outlet. 3. The pre-evaporation premix burner for a gas turbine combustor according to claim 1, wherein the reduction rate of the diameter of the throttle portion is 15 to 30%, and the spread angle of the divergent portion is 20 to 45 °. 4. The premix burner for a gas turbine combustor according to claim 2, wherein the reduction rate of the diameter of the throttle portion is 15 to 30%, and the divergent angle of the divergent portion is 20 to 45 °.