JPH10160162A - Nitrogen oxide reduction structure of gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the production of nitrogen oxides by supplying the combustor of a gas turbine with fuel and air through an inserted preevaporating and premixing pipe member of specified length. SOLUTION: In a gas turbine combustor 10, liquid fuel such as kerosene or the like injected from a fuel injection valve 31 is mixed with the swirling air current through a swirler 32 inside a preevaporating and premixing pipe 20, and is supplied into a liner 11 from the tip of the preevaporating and premixing pipe 20 and then combusted. Here, the flame turns about between the preevaporating and premixing pipe 20 and the inner face of the liner 11, and preheats the preevaporating and premixing pipe 20. Therefore, the evaporation of the liquid fuel is accelerated, and also the mixed gas is heated, and it is supplied to the liner 11 in condition that it is easy to combust. Moreover, a recirculating current which returns to the side of this mixing pipe 20 is made at the center in front of the preevaporating and premixing pipe 20, whereby the combustion gas circulates to the combustion region, and the combustion becomes stable. Hereby, eve if it is thin mixed gas, the stable combustion becomes possible, and the production of nitrogen oxides is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for reducing nitrogen oxides in a gas turbine combustor for reducing nitrogen oxides generated when burning fuel in a gas turbine combustor.

[0002]

2. Description of the Related Art In a gas turbine, a high-temperature, high-pressure combustion gas generated by burning fuel in a combustor drives the turbine to obtain a rotational force. Recently, however, nitrogen oxides have been used to prevent air pollution. Emission regulations are becoming stricter.

[0003] Nitrogen oxides can be reduced by lowering the flame temperature. For this purpose, various configurations such as a low NOx burner, multi-stage combustion, exhaust gas circulation combustion, and water injection have been considered.

[0004] One of the methods capable of reducing such nitrogen oxides is a so-called pre-evaporation premix combustion method.

As shown in FIG. 2, a pre-evaporation pre-mixing pipe 20 is provided upstream of the liner 11 as shown in FIG. 2, and kerosene injected from a fuel injection valve 31 in the pre-evaporation pre-mixing pipe 20. Such a liquid fuel is mixed with air and evaporated to form an air-excess air-fuel mixture, and this air-fuel mixture is supplied into the liner 11 and burned. As a result, combustion with a lean mixture (high fuel efficiency) becomes possible, and as a result, the flame temperature is reduced and the generation of nitrogen oxides can be suppressed. In addition, the emission amount of nitrogen oxides decreases as the mixture becomes leaner.

[0006]

However, even in the structure in which the pre-evaporation pre-mixing pipe is provided as described above, the combustion becomes unstable due to the lean air-fuel mixture, and the combustion becomes unstable. There is a limit to the reduction of nitrogen oxides by chemical conversion.

It is conceivable to stabilize the combustion by providing a pilot burner. However, the combustion by the pilot burner generates nitrogen oxides, so that the nitrogen oxide reduction effect is reduced. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to promote the evaporation of fuel by a pre-evaporation pre-mixing pipe and to enable stable combustion with a leaner air-fuel mixture. An object of the present invention is to provide a nitrogen oxide reduction structure of a gas turbine combustor capable of reducing the emission of nitrogen oxide.

[0009]

A gas turbine combustor according to the present invention, which achieves the above object, has a structure for reducing nitrogen oxides. A premixing pipe member is inserted at a predetermined length, and fuel and air are supplied through the preevaporation premixing pipe.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic longitudinal sectional view of a gas turbine combustor to which an example of a nitrogen oxide reducing structure of a gas turbine combustor according to the present invention is applied.

The illustrated gas turbine combustor 10 is configured such that a burner 30 is provided at the other end of a cylindrical liner 11 having one end open through a pre-evaporation premix pipe 20 as a pre-evaporation pre-mix pipe member. ing.

The pre-evaporation pre-mixing tube 20 is formed of a heat-resistant material such as a ceramic into a cylindrical shape having a predetermined diameter, and is provided with its tip inserted into the liner 11 by a predetermined amount.

The burner 30 has a fuel injection valve 31 provided at the center of the rear end of the pre-evaporation pre-mixing pipe 20, and a swirler 32 provided around the fuel injection valve 31. .

In the gas turbine combustor 10 configured as described above, the fuel injection valve 31 is used during combustion.
Liquid fuel such as kerosene injected from the pre-evaporation mixing pipe 20
And mixed with the swirling airflow through the swirler 32, supplied from the tip of the pre-evaporation pre-mixing pipe 20 into the liner 11 and burned. The ignition is performed by an ignition device (not shown).

Here, the flame caused by the combustion wraps around between the pre-evaporation pre-mixing tube 20 and the inner surface of the liner 11 to heat the pre-evaporation pre-mixing tube 20 as shown in the figure. Therefore, the evaporation of the liquid fuel is promoted, and the air-fuel mixture is heated (preheated) and supplied to the liner 11 in a state where it is easy to burn,
Therefore, stable combustion becomes possible.

Further, at the front center of the pre-evaporation premix pipe 20, a recirculation flow returning to the pre-evaporation pre-mix pipe 20 side is formed as shown by an arrow in the figure, whereby the combustion gas is circulated to the combustion area. Stabilizes combustion.

Further, the tip of the heated pre-evaporation pre-mixing tube 20 acts like a fire and holds the flame, contributing to the stabilization of combustion.

As a result, stable combustion can be performed even with a leaner mixture, and as a result, the generation of nitrogen oxides can be further suppressed.

[0020]

As described above, according to the structure for reducing nitrogen oxides of a gas turbine combustor according to the present invention, a pre-evaporation premix pipe inserted into a combustor of a gas turbine at a predetermined length. Since the fuel and the air are supplied through the members, the pre-evaporation pre-mixing pipe member is heated by the combustion to promote the evaporation of the liquid fuel, and the air-fuel mixture is heated, thereby facilitating the combustion. As a result, stable combustion becomes possible. Further, the tip of the heated pre-evaporation pre-mixing tube serves as a base of the flame and holds the flame, thereby contributing to stabilization of combustion.

Therefore, stable combustion is possible even with a leaner mixture, and as a result, the generation of nitrogen oxides can be further suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a gas turbine combustor to which an example of a nitrogen oxide reduction structure of a gas turbine combustor according to the present invention is applied.

FIG. 2 is a schematic longitudinal sectional view of a gas turbine combustor as a conventional example.

[Explanation of symbols]

 10 Combustor 20 Pre-evaporation pre-mixing pipe (pre-evaporation pre-mixing pipe member)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23R 3/54 F23R 3/54

Claims (1)

[Claims] 1. A pre-evaporation pre-mixing pipe member made of a heat-resistant material and having a cylindrical shape is inserted into a combustor of a gas turbine at a predetermined length, and fuel and air are passed through the pre-evaporation pre-mixing pipe. The nitrogen oxide reduction structure of the gas turbine combustor characterized by being supplied.