JPH04257607A - Combustion apparatus - Google Patents

Abstract

PURPOSE:To improve performance of evaporation and combustion in a combustion apparatus such as an oil fan heater, etc., with a decrease in NOx generation and an expansion in turn down ratio. CONSTITUTION:A combustion apparatus has such a constitution that a burner head 3 is mounted on an evaporation chamber 1 in which liquid fuel is evaporated, fine burner ports are provided on the upper part of the burner head 3, burner ports larger than the fine burner ports on the lower part (6a<6b<6c), and a wire mesh 7 is attached tight around the circumferential face of the burner head 3. Therefore, flames formed on the burner head 3 are small, resulting in a reduction in NOx generation and the temperature at the upper part of the wire mesh 7 is kept high even when combustion rate is lowered. In addition, the flame stability is good as the burner ports on the lower part of the burner head 3 are larger, and the temperature of the evaporation chamber 1 which is easily affected by the flames can be kept high, so that an excellent evaporation and combustion performance can be achieved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premix combustion device used in oil fan heaters and the like.

0002

2. Description of the Related Art Conventionally, as shown in FIG. 5, this type of combustion apparatus has a burner head 23 in the form of a canopied cylinder covering the upper opening of a vaporizing cylinder 22 in which a sheathed heater 21 is embedded. A mixed gas of vaporized fuel and combustion air supplied into the vaporization cylinder 22 is guided into the burner head 23 and then through the flame hole 2.
4 and forms a flame 26 through a wire mesh 25.

0003

[Problems to be Solved by the Invention] However, in the conventional combustion device described above, the flame hole 24 formed in the burner head 23
Since the single opening area of the fuel cell is large, the amount of nitrogen oxides (NOx) emitted is large, and the variable combustion range (TDR) is also narrow. That is, when the volume of the flame 26 formed in the flame hole 24 becomes larger than a certain level, the flame temperature becomes almost the same high temperature, resulting in an increase in flame temperature. Therefore, the emission amount of NOx, which largely depends on the flame atmosphere temperature, was high.

[0004] Furthermore, when the minimum combustion amount is decreased in order to expand the TDR (expanding the variable range of maximum combustion amount and minimum combustion amount), the flame adheres to the flame hole and the temperature of the upper wire gauze becomes extremely high. It was not possible to expand TDR because there was a problem with the issue and there was also the possibility of backfire. Therefore, we considered countermeasures by reducing the area of a single flame hole and increasing the flame hole load, but with this countermeasure, even a slight deviation in the air-fuel ratio at the time of minimum combustion would make it easier to lift, resulting in flame holding power. As the flame becomes weaker, the temperature of the vaporizer cylinder, which is greatly affected by this flame, decreases, which has a negative effect on fuel vaporization performance.

[0005] The present invention solves the above-mentioned problems.
The purpose is to increase R and obtain good vaporization and combustion performance while suppressing NOx emissions.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems of the prior art, the present invention has a first aspect of the present invention, in which small flame holes are provided all around the upper part of the peripheral wall of the burner head, and small flame holes larger than the small flame holes are provided all around the lower part of the peripheral wall of the burner head. A large number of flame holes are provided approximately equally and a wire mesh is tightly attached to the outer periphery of the flame holes.In the second invention, the burner head has a dual structure of inside and outside, and a large through hole is formed outside the burner head, and the burner head is Micro holes are made in the upper part of the peripheral wall inside the head.
Small through holes larger than micro through holes are provided in the lower part on the same axis as the large through holes outside the burner head to form flame holes, and a wire mesh is tightly attached to the outer periphery of the outside of the burner head. .

[0007]

[Function] According to the present invention, with the above structure, in the first invention, since the single opening area of the flame hole is small, the flame volume is also small, and the flame temperature is also lowered, and the amount of NOx discharged is suppressed. Further, by configuring the flame hole in the upper part of the burner head, where the temperature of the wire mesh becomes high, as a small flame hole, the ejection flow velocity of the mixed gas can be increased and the temperature of the wire mesh can be lowered. Furthermore, by making the lower flame hole of the burner head, where the flame holding power is weaker, larger than the upper flame hole, it is possible to reduce the jet flow velocity of the mixed gas and strengthen the flame holding power. This improves heat recovery, prevents a drop in the temperature of the vaporizer cylinder, and provides good vaporization and combustion performance.

Furthermore, in the second invention, since the single opening area of the flame hole provided in the burner head is restricted by the minute through hole formed in the burner head, the flame volume formed there is also reduced. The amount of NOx emissions will be further reduced. Furthermore, each of the above flame holes has a large hole outside the burner head outside of the small hole, so the flame formed in this small hole causes a flow velocity drop in the large hole, and The flame becomes strongly attached to the edges. Therefore, a flame with very strong flame holding power is formed, and the flame velocity is higher in the flame hole parts other than the hole edge than at the hole edge, so the temperature of the wire mesh does not rise as much, and backfire due to expansion of TDR is prevented. There will be no fear.

[0009] Also, since the lower flame hole of each flame hole inside and outside the burner head is larger than the upper flame hole, the flame stability of the flame formed in the lower flame hole located near the vaporizing cylinder is improved. increases, thereby promoting heat recovery from the burner head to the carburetor cylinder, suppressing a decrease in the carburetor temperature due to expansion of TDR (reduction in minimum combustion amount), and achieving good vaporization and combustion performance.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below, taking as an example the case where the burner head has a dual structure.

In FIGS. 1 to 3, reference numeral 1 denotes a bottomed cylindrical vaporizing cylinder with an open top, in which a sheathed heater 2 is embedded. Reference numeral 3 denotes a burner head in the form of a cylinder with a ceiling, in which the flange part of the lower peripheral edge is placed on the opening edge 1a of the vaporizing cylinder 1 and fixed with screws, and the burner head outer 3a and the burner head inner 3b are press-fitted into the upper inner side of the burner head. It is composed of. The outer burner head 3a has a diameter of 3 mm from the top to the bottom around the entire circumference of the peripheral wall.
, large through holes 4a, 4b, and 4c in the order of 3.5 mm and 4 mm, and small through holes in the burner head 3b in the order of diameters 1.5 mm, 1.8 mm, and 2.6 mm from the top to the bottom all around the peripheral wall. 5a, 5b, and 5c are formed, and these through holes are provided coaxially and set to face each other, thereby forming flame holes 6a, 6b, and 6c. Reference numeral 7 denotes a wire mesh stretched around the outer periphery of the burner head outer 3a and spot welded between the lower through holes around the entire circumference of the peripheral wall.

Reference numeral 8 denotes a vaporizing cylinder lid provided in the burner head 3 to cover the opening of the vaporizing cylinder 1, and the opening at the lower center thereof is narrowed to a small diameter to form a mixed gas inlet 8a. Reference numeral 9 denotes a resistance plate having a large number of small holes at a position opposite to the mixed gas inlet 8a of the vaporizer cylinder lid 8, and is fixed to the burner head 3 by pressure. 10 is an ignition electrode for igniting the mixed gas ejected from the flame holes 6a, 6b, and 6c; 11 is a flame; 1
2 is a flame rod as a flame detection sensor. Reference numeral 13 denotes a blower pipe that sends combustion air into the interior of the vaporization cylinder 1, and an air port 14 at the tip is provided on the wall surface of the vaporization cylinder 1.
The other side communicates with the blower 15. 16 is a nozzle connected to an oil supply pipe 18 from a fuel pump 17;
The inside of the vaporizer cylinder 1 is exposed through the inside of 3.

In the above configuration, when the sheathed heater 2 is energized and the vaporization tube 1 is heated to a predetermined temperature, the blower 15
starts and the combustion air passes through the air pipe 13 and enters the air port 14.
The fuel pump 17 is also started, and the fuel is sent from the nozzle 16 to the carburetor cylinder 1 through the oil supply pipe 18.
It is squirted inside. The liquid fuel injected into the vaporization tube 1 is vaporized on the heated side wall surface of the vaporization tube 1, mixed with combustion air, and then sent to the burner head 3, where it is sent to the burner head 3 and then through the flame holes 6a, 6.
It ejects from b and 6c. This mixed gas is then ignited by a spark discharge from the ignition electrode 10 to form a flame 11.

Here, the flame holes 6a, 6 of the burner head 3
The flame formed at points b and 6c has substantially the same flow rate and velocity as the small through holes 5a, 5b, and 5 in the burner head 3b located inside.
Since it is regulated by c, the flame volume is extremely small. Therefore, the flame temperature is lower and the flame length is shorter than that of conventional flames, so the ambient temperature around the burner can be lowered as much as possible. Therefore, a combustion state with a low flame atmosphere temperature can be obtained, and the generation of NOx whose emission amount largely depends on the flame temperature can be suppressed.

[0015] Furthermore, each of the above-mentioned flame holes has minute through holes 5a, 5b, 5
Large through holes 4a, 4b, 4 of burner head outside 3a on the outside of c.
c, the flames formed in the small holes 5a, 5b, and 5c caused a flow velocity drop in the large holes 4a, 4b, and 4c, and attached to the edges of the large holes 4a, 4b, and 4c. It becomes a flame state. Therefore, a flame with very strong flame holding power is formed, and the flame flow velocity is higher in the flame hole parts other than the hole edge compared to the hole edge, so the temperature of the wire mesh 7 does not rise as much, and the opposite effect occurs due to the expansion of TDR. Not only the fire but also the instability of the flame will be eliminated.

[0016] Also, each flame hole 6a, 6 inside and outside the burner head.
In case of b and 6c, the lower flame hole is larger than the upper flame hole (6a < 6b < 6c), so the flame stability of the flame formed in the lower flame hole located near the vaporizer tube 1 is lower. increase,
This promotes heat recovery from the burner head 3 to the vaporizer cylinder 1, suppresses the decrease in vaporizer cylinder temperature due to expansion of TDR (reduction in minimum combustion amount), and makes it possible to obtain good vaporization and combustion performance as well as durability. It is possible to improve tar properties. Furthermore, since the upper flame hole of the burner head 3 is smaller than the lower flame hole, which tends to cause the temperature of the wire mesh 7 to become high, the mixed gas flow rate is also high and the temperature of the wire mesh 7 decreases.
A burner with high heat resistance can be provided.

FIG. 4 shows a case where the burner head 3 is single, and the flame holes 6a, 6b, and 6c of this burner head 3 have small flame holes at the top and larger flame holes at the bottom (6a<6b).
<6c), and its functions and effects are the same as those of the previous example except for flame stabilization.

[0018]

As explained above, the combustion apparatus of the present invention can suppress the generation of nitrogen oxides, further improve the flame holding ability of the flame, and reduce backfire and wire mesh temperature due to expansion of TDR. It is possible to prevent the increase in temperature and the decrease in vaporizer cylinder temperature.
It is possible to provide a high-performance burner that is highly safe and provides good vaporization performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a combustion device in one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a flame hole portion of the combustion device.

FIG. 3 is a sectional view showing the overall configuration of the combustion device.

FIG. 4 is a sectional view of a main part showing another embodiment of the present invention.

FIG. 5 is a sectional view of a conventional combustion device.

[Explanation of symbols]

1. Vaporizer cylinder 3 Burner head 3a　Outside burner head 3b Inside the burner head 4a, 4b, 4c large through hole 5a, 5b, 5c microscopic holes 6a, 6b, 6c flame hole 7. Wire mesh

Claims (2)

[Claims] [Claim 1] A vaporizing cylinder having an opening, and a burner head in the form of a ceiling cylinder covering the opening of the vaporizing cylinder,
The above-mentioned burner head has small flame holes all around the upper part of the peripheral wall, a large number of flame holes larger than the small flame holes all around the lower part, and a wire mesh tightly attached to the outer periphery of the burner head. Device. 2. A vaporizing cylinder having an opening, and a burner head in the form of a ceiling cylinder covering the opening of the vaporizing cylinder,
The above-mentioned burner head has a double structure inside and outside, with a large through hole formed outside the burner head, a small through hole in the upper part of the peripheral wall inside the burner head, and a small through hole larger than the small through hole in the lower part. A combustion device in which holes are provided coaxially with large through holes outside the burner head to form flame holes, and a wire mesh is provided in close contact with the outer periphery of the outside of the burner head.