Combustion Apparatus

Abstract

A combustion apparatus according to the present invention can positively control and generate burnt gas recirculation with a simple structure. The combustion apparatus has an annular container (12) having an inner cylindrical portion (15) forming an inner circumferential side surface, an outer cylindrical portion (13) forming an outer circumferential side surface, an open end (26), and a close end (10). A flow (28) of air is formed so as to have a velocity component in the direction of a central axis (J) from the open end (26) to the close end (10) and a velocity component to swirl in a circumferential direction of the annular container (12). Fuel (23) is injected so as to have a velocity component in the direction of the central axis (J) from the close end (10) to the open end (26) and a velocity component directed radially outward.

Description

TECHNICAL FIELD[0001]The present invention relates to a combustion apparatus, and more particularly to a combustion apparatus for supplying combustion air and fuel to a combustion chamber to mix and combust the combustion air and the fuel.BACKGROUND ART[0002]Regulation regarding air pollutants discharged from a combustion apparatus, particularly nitrogen oxide (NOx), becomes stricter and stricter. Thus, there has been demanded technology to reduce discharge of NOx.[0003]Nitrogen oxide (NOx) is generally classified according to its generation mechanism into three types: thermal NOx, prompt NOx, and fuel NOx. Thermal NOx is generated when nitrogen in air reacts with oxygen at a high temperature, and greatly depends on temperature. Prompt NOx is generated particularly in a flame of fuel-rich condition. Fuel NOx is generated while nitrogenous compounds contained in fuel are converted.[0004]Recently, clean fuel including no nitrogenous compounds has been used in many cases. In such cases...

AI Technical Summary

Benefits of technology

[0057]Further, in the gas turbine combustion apparatus to which the combustion apparatus of the present invention is applied, it is possible to enhance the stability and maximize effects of burnt gas recirculation. Accordingly, it is possible to suppress generation of thermal NOx in a case of liquid fuel, in which it has been difficult to reduce NOx with the conventional technology.

[0058]As described above, in the combustion apparatus of the present invention, since an inner wall of the combustion apparatus is suitably cooled by an air flow having a low temperature, it is possible to provide a gas turbine combustion apparatus having a high durability.

[0059]Further, in the combustion apparatus of the present invention, because of a simple structure, it is possible to provide a gas turbine combustion apparatus which can readily use a heat resista

Problems solved by technology

As compared to the aforementioned reduction of fuel NOx and prompt NOx, reduction of thermal NOx is most difficult and is becoming a key of NOx reduction technology in recent years.

However, premixed combustion has problems that a stable combustion range is so narrow that backfire or blow-off is likely to occur.

Further, there is a defect that liquid fuel cannot be premixed unless the fuel has previously been evaporated (pre-evaporated).

Thus, there is a limit to reduction of thermal NOx.

However, the size of the combustion apparatus problematically becomes large by the pre-evaporation portion.

However, such technology has been employed in many large-sized combustion furnaces but cannot be applied to small-sized combustion apparatuses because a supply system of fuel or air becomes complicated.

Further, it is difficult to find optimal supply locations of fuel or air and optimal division ratios, or to control these locations and division ratios according to loads.

However, a burnt gas recirculation flow centrally downstream of the flame holding plate does not reach a portion in which fuel is mixed with air before ignition.

Accordingly, this technology is not suited for purposes where the size of a combustion chamber of a combustion apparatus of a gas turbine or the like should be made as small as possible.

Further, it is difficult to apply this technology to liquid fuel.

However, a structure of a burner becomes complicated due to the divided flame.

Accordingly, the size of the burner problematically becomes large (a combustion load per volume is low).

Further, it is difficult to apply this technology to liquid fuel.

Accordingly, there is a problem that effect to make combustion slow is small.

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