JPH11294722A - Oxygen burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress NOx concentration at a low level in the case where an oxygen usage is saved, by comprising an oxygen nozzle for ejecting a high oxygen gas around a fuel nozzle, and comprising air nozzles further outer periphery of the oxygen nozzle. SOLUTION: A fuel nozzle 1 for ejecting fuel is provided at the central portion of an oxygen nozzle 2 to which a high oxygen gas, i.e., pure oxygen or high concentration oxygen is supplied. A plurality of air nozzles 3 are arranged at the outer periphery of the oxygen nozzle 2 in a row with an equal angular interval therebetween. Alternatively, the air nozzle 3 may be arranged around the fuel nozzle 1, and a plurality of the oxygen nozzle 2 may be arranged in a row at the outer periphery thereof. In this case, the high oxygen gas and a combustion air are not mixed in advance but separately ejected. In such a system a nitrogen concentration becomes low in a high oxygen gas for conducting high-temperature combustion, resulting in lowering of an NOx generation rate, which, however, falls short of the NOx effect of the former structure since the surrounding air is in contact with the high-temperature portion. Nonetheless, temperature rise of the fuel nozzle 1 and the inner wall of a combustion cylinder can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low NOx oxygen burner.
It is about the conversion.

[0002]

2. Description of the Related Art FIG. 4 shows the structure of a conventional oxygen burner in which pure oxygen or high-concentration oxygen (hereinafter referred to as high oxygen gas) is used instead of combustion air. FIG.
(A) shows the relationship between the oxygen concentration in the oxygen burner and the flame temperature. Generally, the higher the oxygen concentration, the higher the flame temperature. High-concentration oxygen having an appropriate oxygen concentration is used depending on the flame temperature. Also, as is clear from this graph, the flame temperature tends to be saturated as the oxygen concentration increases, and for example, the oxygen concentration is 6%.
When used at around 0%, the flame temperature is relatively high, the amount of oxygen used can be reduced, and the efficiency is high. Therefore, usually, as shown in FIG. 5, air is mixed with high oxygen gas to obtain a desired oxygen concentration. I'm using

[0003]

However, the above-described conventional configuration has the following problems. Curve A in FIG. 7 (b) is obtained by measuring the relationship between the oxygen concentration in the combustion air and the NOx concentration in the exhaust when the oxygen burner in FIG. 4 or 5 is used. The NOx concentration is highest around 60% oxygen concentration. That is, when the amount of nitrogen gas is abundant, the amount of NOx increases with an increase in the temperature, but when the amount of nitrogen gas decreases, the amount of NOx tends to decrease in proportion to the nitrogen concentration. Therefore, as shown in FIG. If an appropriate amount of air is mixed with the high oxygen gas supplied to the oxygen burner to reduce the fuel cost of the oxygen burner, the amount of NOx generated in the exhaust gas increases.

FIG. 6 shows an application of a two-stage air combustion system known as a method for reducing NOx to an oxygen burner operated with a reduced amount of oxygen as described above.
Curve B in (b) is obtained by measuring the NOx concentration by the oxygen burner in FIG. According to this method, the first stage causes a shortage of oxygen and slows combustion, so that although a slight NOx reduction effect is recognized, it was not completely satisfactory. Therefore, an object of the present invention is to provide an oxygen burner of this type which can solve the above-mentioned problems and can suppress the NOx concentration which becomes a problem when the oxygen consumption is reduced. It is.

[0005]

As shown in FIG. 1 (a) or (b), an oxygen burner according to the present invention has a high oxygen gas (pure oxygen or high concentration) around a fuel nozzle 1 for ejecting fuel. An oxygen nozzle 2 for ejecting oxygen) and an air nozzle 3 on the outside thereof, or FIG.
As shown in FIG. 1, an air nozzle 3 is provided around a fuel nozzle 1 and an oxygen nozzle 2 for jetting high oxygen gas outside the air nozzle 3.
By making a relatively high temperature part with high oxygen concentration in the flame and a relatively low temperature part with low oxygen concentration and high nitrogen concentration in the flame, the nitrogen component is kept as high as possible in the flame. The feature is that the amount of NOx generated is suppressed by preventing the contact.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows an embodiment of an oxygen burner according to the present invention. As the fuel, a gaseous fuel such as natural gas or propane gas may be used. Or other liquid fuels. A fuel nozzle 1 for ejecting fuel is provided at a central portion of an oxygen nozzle 2 to which high oxygen gas, that is, pure oxygen or high concentration oxygen is supplied, and a plurality of air nozzles 3 at equal angular intervals outside the oxygen nozzle 2. Are lined up. FIG. 3 shows the NOx reduction effect of the present invention in comparison with the conventional example.
7A and 7B show the measurement results according to the embodiment of the present invention, and curves A and B are again obtained by reprinting the conventional example shown in FIG. 7B. FIG. 1 (b) shows another embodiment of the present invention, in which a flame is formed outside the burner to improve the durability of the fuel nozzle 1. This is almost the same as the case of FIG.

FIG. 2 shows another embodiment of the present invention, in which an air nozzle 3 is provided around a fuel nozzle 1 and a plurality of oxygen nozzles 2 are further arranged outside the air nozzle 3. The NOx reduction effect is shown by curve D in FIG. Also in this case, similarly to the case of FIG. 1, the high oxygen gas and the combustion air are separately injected without premixing. Also in this method, the nitrogen concentration becomes lower in the high oxygen gas which performs high-temperature combustion, so that the NOx generation rate is lower than that of the conventional example. It does not reach the NOx effect. However, since the temperature rise of the fuel nozzle 1 and the inner wall of the combustion cylinder in FIG. 1 can be suppressed, there is an advantage that the durability of the burner is improved.

[0008]

According to the present invention, as described above, in an oxygen burner of the type in which air is mixed with oxygen to reduce fuel costs, the problem of NOx generation occurring for cost saving can be solved by a very simple structure. It has the advantage that it can be eliminated, and because it is supplied to the burner without mixing oxygen and air in advance, it does not require the mixer 5 as shown in FIG. Although there was a problem that high oxygen gas could not be preheated by heat, this method has an advantage that air can be preheated.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a longitudinal sectional view and (b) is a front view.

FIG. 2 shows another embodiment of the present invention, wherein (a) is a longitudinal sectional view and (b) is a front view.

FIG. 3 is a graph showing the effect of the present invention.

FIG. 4 is a longitudinal sectional view showing a conventional example.

FIG. 5 is a longitudinal sectional view showing another conventional example.

6A and 6B show still another conventional example, in which FIG. 6A is a longitudinal sectional view, and FIG. 6B is a front view.

FIGS. 7A and 7B are graphs showing the operation of an oxygen burner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel nozzle 2 Oxygen nozzle 3 Air nozzle 4 Burner body 5 Mixer

Claims (3)

[Claims] 1. A gaseous fuel such as natural gas or propane gas;
Alternatively, an oxygen burner including an oxygen nozzle for ejecting pure oxygen or high-concentration oxygen around a fuel nozzle for ejecting liquid fuel such as heavy oil or kerosene, and further including an air nozzle on the outside thereof. 2. A gaseous fuel such as natural gas or propane gas;
Alternatively, an oxygen burner including an air nozzle around a fuel nozzle for ejecting a liquid fuel such as heavy oil or kerosene, and an oxygen nozzle for ejecting pure oxygen or high-concentration oxygen outside the fuel nozzle. 3. The oxygen burner according to claim 1, wherein air supplied to the air nozzle is preheated by exhaust gas.