JPH04126904A - Low-nox burner - Google Patents

Abstract

PURPOSE:To reduce the generation of NOx without interfering with the combustion efficiency and stabilize the combustion by setting the relative positions of a header and an air cone in such a manner that either fuel jets or air jets are rotationally asymmetrical in relation to the axis of the air cone. CONSTITUTION:A header 1 and an air cone 2 are fitted together not coaxially but with the header 1 displaced by a distance of (d) upward from the axis of the air cone 2. The air supplied through an air outlet 5 is adjusted to a quantity necessary and sufficient as a whole for complete combustion and is delivered evenly therefrom. The air comes short of the average in the upper half of the flaming region, whereas air is oversupplied in the lower half. Therefore, downstream from the burner, the combustion produces a flame which is asymmetric in relation to the center of the air cone with a portion forming a flaming region oversupplied with fuel and the other portion, a flaming region oversupplied with air, that is, formation of a flame produced in part by concentrated combustion and in part by thin combustion. This decreases the average temperature of the flame and hence restrains the generation of NOx.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a burner that burns fuel such as gas, oil, or pulverized coal, and particularly relates to a burner that suppresses the generation of nitrogen oxides NOx without reducing combustion efficiency. About the burner you get.

[Conventional technology]

Burners for burning gas, heavy oil, or pulverized coal are widely used, but conventional burners inject fuel and air coaxially and rotationally symmetrically to mix them as uniformly as possible. This type of burner is designed to burn, and when trying to increase the combustion efficiency of this type of burner, there is a problem in that a high concentration of NOx is generated.

This NOx has recently become a problem from the viewpoint of environmental conservation, and there is a strong demand to suppress its generation.

[Problem to be solved by the invention]

The present invention has been made to solve the above problems, and its purpose is to provide a burner that can reduce NOx generation and provide stable combustion without impairing combustion efficiency. be.

[Means for Solving the Problems and Their Effects] The above object is to make the jet flow of fuel and air inside the burner non-uniform in the circumferential direction around the central axis of the air cone,
This is achieved by means of a burner that generates a relatively excess of air and a relatively excess of fuel in the above-mentioned directions, thereby burning the fuel in a concentrated manner.

More specifically, the above purpose is to arrange the axes of the header that injects fuel and the air cone surrounding the header so that they are not coaxial, but are spaced apart from each other by a certain distance, or in parallel. This is achieved by arranging the central axes so that they intersect.

The present invention can be applied to gas burners, oil burners, and pulverized coal burners.

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a burner according to the present invention;
FIG. 2 is a front view thereof, FIG. 3 is a sectional view showing another embodiment, and FIG. 4 is a graph showing the NOx reduction effect of the gas burner according to the present invention.

It should be noted that these drawings are simplified to illustrate the principles of the present invention, which can actually be applied to all types of known gas burners, oil burners, and pulverized coal burners.

In Fig. 1, ■ is a header equipped with a nozzle 1a for injecting fuel, 2 is an air cone, 3 is a fuel supply pipe,
Reference numeral 4 designates an air plate provided to form an air outlet between the inner wall surface of the air cone l and stably burn the fuel, and 5 an air outlet.

In the embodiment shown in FIGS. 1 and 2, the header 1 and the air cone 2 are not coaxial, but are parallel to each other with a certain distance d between their central axes. 1 is shifted upward from the center of the air cone 2 by a distance d.

The amount of air supplied from this air outlet is adjusted to be necessary and sufficient for complete combustion as a whole, and is uniformly blown out from the air outlet 5.

However, since the header that injects the fuel is shifted above the center of the air cone by a distance d, the upper half of the flame area in Figure 2 has less air than average, and conversely It becomes excessive in the lower half.

For this reason, the flame generated by combustion becomes asymmetrical with respect to the center of the air cone, resulting in either concentrated or light combustion.

That is, in front of the flame emitting port, a flame region with excess fuel and a flame region with excess air coexist, and concentrated combustion is performed, thereby reducing the average temperature of the flame and suppressing the generation of NOx.

Although the distance d between the two central axes depends on the burner diameter and combustion load, it is generally 2% or more of the air cone diameter.
% or less, preferably 5% or more or more 1 Distance d between the two central axes
If it is less than the above lower limit, the NOx suppression effect will be reduced, and if it is more than the above upper limit, combustion will become unstable, vibrations will occur, and hydrocarbons in the combustion exhaust gas will increase.

An example of the NOx reduction effect of the gas burner according to the present invention is shown in the fourth example.
As shown in the figure. From this figure, it is clear that when the present invention is used, the amount of NOx generated can be halved compared to the conventionally known burner.

Next, FIG. 3 will be explained.

In the embodiment shown in FIG. 3, the central axis of the header 1 and the central axis of the air cone 2 are not parallel but intersect with each other at a slight angle θ.

For this reason, this burner is also configured so that in front of it there is an area in which there is excess air and an area in which there is excess fuel, respectively, compared to the overall average, so that concentrated combustion is performed and a reduction in NOx is achieved.

As explained above, in the present invention, in front of the flame emission port, a flame region where air is somewhat scarce and has a relatively high concentration of fuel is mixed with an excessive flame region where air is relatively low in fuel. However, this reduces the average temperature of the flame and reduces the generation of NOx.

However, according to the present invention, the fuel combustion efficiency is maintained the same as in conventional burners.

The configuration of the present invention is not limited to the embodiments in progress, but includes all embodiments that can be easily conceived by a person skilled in the art from the description in the progress, such as using an auxiliary header or nozzle together with the main header. It is something to do.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a burner according to the present invention;
FIG. 2 is a front view thereof, FIG. 3 is a sectional view showing another embodiment, and FIG. 4 is a graph showing the NOx reduction effect of the gas burner according to the present invention. 1------1--Header 2-------1--Air cone-Fuel supply pipe--Air play 1--

Claims (6)

[Claims] (1) In a burner equipped with a header (1) having a fuel injection nozzle and an air cone (2) having a flame emitting port and provided so as to surround the header, a jet of fuel and air is generated at least The above-mentioned burner is characterized in that the relative positions of the header and the air cone are determined such that either one is rotationally asymmetric with respect to the central axis of the air cone. (2) The burner according to claim 1, wherein the center axes of the header and the air cone are parallel to each other with a certain distance d between them. (3) The burner according to claim 1, wherein the central axis of the header and the central axis of the air cone are arranged to intersect. (4) The burner according to any one of claims 1 to 3, wherein the fuel is gas. (5) The burner according to any one of claims 1 to 3, wherein the fuel is oil. (6) The burner according to any one of claims 1 to 3, wherein the fuel is pulverized coal.