JPS6027888B2 - Low NOx combustion method for combustion chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a combustion chamber with a plurality of burners.
×Regarding combustion method.

When the N○× generated on the upstream side of the flame and combustion gas flow in the combustion chamber is introduced into the downstream flame, the N○× is reduced by reducing agents such as HC, HCN, and NH3 generated in the flame.
It was confirmed through experiments that N2 is reduced to N2.

Therefore, the present inventors made the upstream burner a normal burner, and made the downstream burner a long flame by blowing out fuel and combustion air (in whole or in part) from separate holes. We have developed a low-N○× combustion method in which a large amount of N○× generated in the upstream burner is passed through this long flame and reduced to N2. However, in a burner structure in which fuel and combustion air are blown out from separate holes, if there are a large number of burners, the walls of the combustion chamber will be full of holes, making it difficult to apply the low N○× combustion method to the existing combustion chamber. The major problem with this is that the walls of the combustion chamber would have to be extensively remodeled.

The present invention has been made to solve such problems,
While blowing out fuel and combustion air from the same hole, the flame of the burner is lengthened, and the N○× generated in the upstream burner is passed through the flame.
The present invention aims to provide a low N○k combustion method in a combustion chamber that reduces the amount of nitrogen through the combustion chamber. In a burner, one of the factors that causes the flame to be short is that the fuel and combustion air mix early and strongly. This means that in order to achieve a long flame, it is sufficient to prevent early mixing of fuel and combustion air. It is important to prevent mixing at an early stage, that is, near the burner; if the two do not mix even when moving away from the burner, unburned parts will increase. The present invention focuses on this point, and blows combustion gas concentrically between the fuel blown into the center of the burner on the downstream side and the combustion air blown outward. The flame of the burner is made longer by preventing air from mixing near the burner, and HC, HCN, and NH3 generated in the long flame pass through the NOk generated in the upstream burner into this long flame.
It is designed to reduce the production of N○× by reducing it to N2 using a reducing agent such as.

Below, the low-N open combustion method for combustion chambers according to the present invention will be explained using diagrams. Figure 1 shows an example of the structure of the downstream burner when this method is applied to an oil-fed combustion chamber; 2 is a sprayer provided at the tip of the gun, 3 is a combustion air blowing passage provided around the oil gun 1, 4 is a swirler provided at the tip of the blowing passage, and 5 is a blower of the blowing passage 3. A combustion gas blowing passage provided around the combustion gas blowing passage 6 is a combustion air blowing passage provided around the combustion gas blowing passage.

In a burner having such a structure, oil is sprayed from the atomizer 2 at the tip of the oil gun 1, and a part of the combustion air is swirled from the blowing passage 3 around the oil gun 1 by the swirler blade 4 at the tip. It is supplied to hair oil and burns to form a primary flame F.

If the part of the combustion air is small, the primary flame F will be small and weak, and will simply function as a flame-holding flame.
Most of the combustion air is supplied from the outermost blowing passage 6, and is blown into the combustion chamber while going straight or gently swirling. Combustion gas is supplied from the blowing passage 5 between the blowing passage 38'6 and separating the secondary flame F from most of the combustion air supplied from the outermost blowing passage 6. Thus, most of the combustion air cannot mix with the atomized oil or the primary flame F near the burner, but rather at a distance from the burner, so that the resulting secondary flame F' has a longer flame. This secondary flame F' has a large flame, and the center of the flame is surrounded by combustion gas and isolated from the air, and a large amount of HC, HCN,
Reducing agents such as NH3 are generated and form a reducing atmosphere over a wide area. At this time, by appropriately setting and adjusting the amount of combustion gas, axial velocity, swirling force, etc., a flame of a desired shape is produced. The above-mentioned reducing atmosphere envelops the flame (N water) passage on the upstream side and denitrates it. Figure 2 shows another example of the structure of the downstream burner when this method is applied to an oil-fired combustion chamber. 1 is an oil gun with a sprayer 2 at its tip, around which combustion gas is blown A passage 5' is provided, and a combustion air injection passage 6' is further provided around the injection passage 5'.

In a burner with such a structure, oil is sprayed from a sprayer at the tip of the oil gun 1, combustion gas is supplied from a blowing passage 5' around the oil gun, and combustion air is supplied to a blowing passage 6 outside the oil gun.
Supply the entire amount from '.

The mist oil thus burns far from the burner, producing a flame F'. At this time, by appropriately setting or appropriately adjusting the axial velocity and swirling force of the combustion air, the amount of combustion gas, the axial velocity, the swirling force, etc., a flame of a desired shape is generated. Since flame stabilization does not occur in this embodiment, in order to generate flame stabilization, a part of combustion air is mixed with the combustion gas and supplied, and a swirling blade is installed at the tip of the combustion gas blowing passage 5'. It is good to have one. In addition, in the low N○k combustion method of the present invention, exhaust gas recirculation that infiltrates combustion gas into the combustion air may be applied, or only a portion of the combustion air may be supplied to the burner. However, a two-stage combustion method in which the remaining combustion air is supplied to other holes other than the burner, such as near the exit of the combustion chamber, may also be applied to this method if necessary.Furthermore, in this method, A part of the combustion air may be mixed into the combustion gas used to separate the fuel and the combustion air.

As can be seen from the above explanation, the combustion chamber according to the present invention has a low N○×
In the combustion method, combustion gas is injected between the fuel that is blown into the center of the burner downstream of the combustion chamber and the combustion air that is blown outside the combustion chamber, and the combustion gas is separated to maximize the flame of the burner. Since NO gas generated in the upstream burner is passed through the longest flame, NOx is HC, HCN, and NH3 generated in the long flame.
It is reduced to N2 by a reducing agent such as, and the combustion of the fuel in the combustion chamber becomes a low NOx combustion.

Therefore, the present method can be easily applied to existing combustion chambers without any modification, and the excellent effect is that fuel can be burned with low NOx.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the structure of a burner on the downstream side of an oil-fired combustion chamber to which the present method is applied, and FIG. 2 is a sectional view showing another example. DESCRIPTION OF SYMBOLS 1...Oil gun, 2...Atomizer, 3...Combustion air blowing passage, 4...Swirl blade, 5, 5'...Combustion gas blowing passage. 6, 6'... Combustion air blowing passage, F
...Primary flame, F'...Secondary flame, F''...Flame. Figure 1 Figure 2

Claims (1)

[Claims] 1 In a combustion chamber with multiple burners, the upstream burner is a normal burner, and the downstream burner is used to blow combustion gas between the fuel blown into the center and the combustion air blown concentrically outside. The burner creates a reducing atmosphere in a wide area by separating the fuel and combustion air and making the flame longer, and passes NOx generated in the upstream burner into the reducing atmosphere and reduces it to N_2. A low NOx combustion method in the combustion chamber characterized by the following.