JP3132941B2 - Gas turbine premixed combustor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premixed combustor for a gas turbine, and more particularly, to a premixed combustor in which the mixing of fuel and air is made uniform to effectively reduce NOx. About the vessel.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a conventional premixed combustor of a gas turbine. In FIG. 2, a pilot nozzle 02 is disposed at the center of a premixed combustor 01 of a gas turbine. A plurality of cylindrical premix nozzles (main nozzles) 03 are arranged on the same circle around the pilot nozzle 02. In this case, the tip of each premix nozzle 03 is made substantially flush with the tip of the pilot nozzle 02. In addition, 04 is a combustion chamber, 0
Reference numeral 5 denotes a turning blade.

[0003]

Recently, the amount of NOx discharged into the atmosphere has been increasing with the rise of the gas turbine inlet temperature. In Japan, where environmental regulations are strict, achieving low NOx is indispensable. Therefore, there is a great demand for reducing NOx in exhaust gas, and various studies have been made. In this case, the mixture of fuel and air is an important factor because the rise in gas temperature increases the proportion of combustion air.

[0004] However, the conventional premixed combustor of the gas turbine shown in FIG. 2 is composed of only cylindrical premixed nozzles because of the necessity of making the structure compact. Is not always good, and N
There was a limit to the reduction of Ox.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems of the prior art, and premixed combustion of a gas turbine in which mixing of fuel and air is made uniform to effectively reduce NOx. The purpose is to provide a vessel.

[0006]

In order to solve the above-mentioned problems, the present invention provides a premixed combustor for a gas turbine, in which a plurality of cylindrical premixed nozzles having swirling blades are arranged on the same circumference. The first premixing nozzle is disposed inside the premixing nozzle, and an annular premixing nozzle is provided adjacent to the downstream side of the first mixing chamber. Further, the outlet end of the inner cylinder defining the inner peripheral side of the second mixing chamber is expanded radially outward toward the downstream combustion chamber so as to narrow the premixed gas flow path.

[0007]

According to the above-mentioned means, the first fuel and air first flow in each of a plurality of cylindrical premix nozzles having swirling vanes.
The mixing of the stages is performed, and then the fuel is mixed with the air in the second premixing nozzle in the annular premixing nozzle, so that the fuel and the air become a uniform mixture, and the combustion in the combustion chamber is improved. , NOx can be reduced.

Further, the flow rate of the air-fuel mixture is increased by flowing to the combustor through the narrowed pre-air-fuel gas flow path.
Flashback is prevented and flame holding is improved.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a premixed combustor for a gas turbine according to the present invention.

In FIG. 1, a pilot nozzle 2 is disposed at the center of a premixed combustor 1 of a gas turbine.
A plurality of cylindrical premix nozzles 3 are arranged on the same circle around the pilot nozzle 2. Each of these premix nozzles 3 is a conventional premix nozzle 0 shown in FIG.
3, and has a swirling blade 5 therein. An annular premix nozzle 6 is provided adjacent to the downstream side of the cylindrical premix nozzle 3. Therefore, the inside of each cylindrical premixing nozzle 3 is a first mixing chamber for fuel and air, and the inside of the annular premixing nozzle 6 is a second mixing chamber. Further, the outlet end 8 of the inner cylinder 7 defining the inner peripheral side of the second mixing chamber is expanded radially outward toward the downstream combustion chamber 4 to have a cone shape. Is narrowed.

Next, the operation will be described. The first-stage mixing of fuel and air is performed in each of the cylindrical pre-mixing nozzles 3 having the swirling blades 5, and thereafter, the fuel and air are merged and the second-stage mixing is performed in the annular pre-mixing nozzle 6. hand,
The fuel and the air become a uniform mixture, the combustion in the combustion chamber 4 becomes good, and the generation amount of NOx can be reduced.

The air-fuel mixture passes through the combustion chamber 4 through a pre-air mixture passage narrowed by a cone-shaped outlet end 8 of an inner cylinder 7 defining an inner peripheral side of an annular premix nozzle (second mixing chamber) 6.
As a result, the flashback is prevented, and a reliable circulating flow can be formed inside the cone-shaped outlet end 8 of the inner cylinder 7, thereby improving the flame holding property.

FIG. 3 shows the fuel concentration distribution at the nozzle outlet of the premixed combustor according to the present invention shown in FIG. 1, and FIG. 4 shows the fuel concentration at the nozzle outlet of the conventional premixed combustor shown in FIG. The respective concentration distributions are shown. 3 and 4, x indicates the distance from the point where the mixed gas from the pilot nozzle and the mixed gas from the main nozzle merge.
As can be seen by comparing these figures, in the conventional premixed combustor, the fuel concentration distribution varies at the nozzle outlet, whereas in the premixed combustor according to the present invention, the mixed gas from the main nozzle is observed. Has a substantially uniform fuel concentration distribution at the junction.

FIG. 5 shows the NOx concentration based on the combustion test result of the premixed combustor according to the present invention, and FIG. 6 shows the NOx concentration based on the combustion test result of the conventional premixed combustor. The solid lines in FIGS. 5 and 6 connect the points judged to be the best, including other results such as the CO concentration. As can be seen by comparing these figures, under the rated load condition of the actual machine indicated by point A, the present invention can reduce the NOx concentration to half compared with the conventional example.

[0015]

As described above, according to the present invention, in a premixed combustor for a gas turbine, mixing of fuel and air is performed by performing mixing of fuel and air in two stages. It is possible to provide a premixed combustor that can make uniform and improve combustion, reduce the amount of generated NOx, and thus contribute to improving the quality of a gas turbine and sufficiently cope with environmental regulations. .

Further, according to the present invention, the mixture of the fuel and the air, which are uniformly mixed, is caused to flow into the combustion chamber through the throttled premixing flow path, and the flow velocity is increased, thereby preventing and maintaining flashback. Flammability can also be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a premixed combustor for a gas turbine according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional premixed combustor of a gas turbine.

FIG. 3 is a diagram showing a fuel concentration distribution at a nozzle outlet of a premixed combustor according to the present invention.

FIG. 4 is a diagram showing a fuel concentration distribution at a nozzle outlet of a conventional premixed combustor.

FIG. 5 is a diagram showing NOx concentration based on a combustion test result of a premixed combustor according to the present invention.

FIG. 6 shows NO based on a combustion test result of a conventional premixed combustor.
It is a figure which shows x density.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Premixed combustor 2 Pilot nozzle 3 Cylindrical premixed nozzle (first mixing chamber) 4 Combustion chamber 5 Swirling blade 6 Annular premixed nozzle (second mixing chamber) 7 Inner cylinder 8 Exit end of inner cylinder

Continuation of the front page (72) Inventor Tetsuo Gora 2-1-1, Shinhama, Araimachi, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Inside Takasago Research Laboratory (56) References JP-A-4-227414 (JP, A) JP-A Heihei 1-137117 (JP, A) JP-A-59-101551 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23R 3/30 F23R 3/34

Claims (1)

(57) [Claims] In a premixed combustor for a gas turbine, a plurality of cylindrical premix nozzles having swirling blades are arranged on the same circumference, and each of these premix nozzles serves as a first mixing chamber. Further, an annular premix nozzle is provided adjacent to the downstream side of the first mixing chamber, an inside of the premix nozzle serves as a second mixing chamber, and an inner cylinder defining an inner peripheral side of the second mixing chamber. Of the outlet end of the radially outward toward the downstream combustion chamber,
A premixed combustor characterized in that the premixed gas flow path is narrowed.