JP4052640B2 - Burner to prevent unevenness of flame - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a burner that prevents unevenness of flame.
[0002]
[Prior art]
A combustion chamber provided in the center of the boiler is surrounded by a water pipe arranged in an annular shape, and a burner that switches the combustion amount in stages is provided in the upper center of the combustion chamber, and combustion control is performed according to the required amount of steam. Boilers are widely used. An outline of the boiler is shown in FIG. When performing three-position combustion control with an oil burner, a low combustion nozzle 4 and a high combustion nozzle 5 are provided in the burner, and fuel is sprayed only from the low combustion nozzle 4 during low combustion, and low during high combustion. The amount of combustion is adjusted by spraying fuel from both the combustion nozzle 4 and the high combustion nozzle 5. The amount of combustion air supplied is also adjusted according to the amount of combustion, and the amount of combustion air supplied from the combustion air outlet 7 provided at the peripheral portion of the burner 1 is reduced during low combustion and during high combustion. Do more. The low-combustion nozzle 4 and the high-combustion nozzle 5 spray fuel toward the combustion chamber 6 in a divergent manner, and the fuel in the form of fine particles is ejected from the combustion air outlet 7 directly downward. Combustion is mixed with the combustion air.
[0003]
In the burner having the low combustion nozzle 4 and the high combustion nozzle 5, the low combustion nozzle 4 and the high combustion nozzle 5 are installed side by side in one nozzle adapter 8, and the low combustion nozzle 4 and the high combustion nozzle 5 are arranged. 5 is arranged so that the midpoint of 5 overlaps the central axis of the combustion chamber 6. By arranging the central axis of the burner 1 so as to overlap the central axis of the combustion chamber, the low combustion nozzle and the high combustion nozzle are separated from the central axis of the combustion chamber by the same distance. In a burner in which the position where the fuel and the combustion air are mixed is shifted to the downstream side by widening the gap between the nozzle and the combustion air outlet 7, the fuel and the combustion air are not mixed until the fuel and the combustion air are mixed. The amount of NOx generated can be reduced by the effect of two-stage combustion that becomes combustion and complete combustion after mixing.
[0004]
However, in a burner in which the mixing position of fuel and combustion air is shifted to the downstream side, if the distance from the combustion air outlet to the mixing position of fuel and air differs depending on the location in the burner, There is a problem that the combustion is first performed on the side where the distance to the mixing position is short, and the flame is biased toward the side where the fuel and air are mixed first. When the combustion air jets 7 are arranged on a circumference with the burner central axis as the center, and the low combustion nozzle 4 is provided at a position away from the burner central axis by a certain distance, the combustion air jet 7 on the right side in FIG. The distance between the air outlet 7 and the low combustion nozzle 4 is such that the low combustion nozzle 4 is farther from the burner central axis than the distance between the left combustion air outlet 7 and the low combustion nozzle 4. It is shortened by 2 times. Since the low combustion nozzle 4 sprays fuel in a conical shape, in the case of low combustion, the fuel and combustion air are mixed on the right side of the combustion chamber and the fuel and combustion air are mixed on the left side of the combustion chamber. In the position where it does, a difference arises in the distance from the combustion air jet tip. Combustion progresses at an early stage on the right side of the combustion chamber, and combustion is delayed on the left side of the combustion chamber. Therefore, the amount of combustion increases on the right side of the combustion chamber with fast combustion, and the spread of the flame in the right direction increases. Since the amount of combustion at is less, the spread of the flame to the left is less. When the bias of the flame occurs in the combustion chamber, the flame comes into contact with the combustion chamber wall surface 10, and the combustion chamber wall surface 10 is overheated by the flame and the fuel that could not be burnt is generated, and further, the combustion is incomplete. It was supposed to have an adverse effect such as becoming.
[0005]
Therefore, as described in Japanese Patent Application No. 2002-104609, it has been considered to prevent the unevenness of the flame by bringing the low combustion nozzle closer to the central axis of the combustion chamber. However, even in this case, the difference in distance from the high combustion nozzle to the mixing position of the fuel sprayed and the combustion air could not be eliminated. Therefore, in the case of a burner with a large turndown and a large difference in the amount of fuel spray between the low combustion nozzle and the high combustion nozzle, there is a bias of the flame during high combustion and the flame may come into contact with the combustion chamber wall surface. there were.
[0006]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to eliminate the bias of the flame in the oil fuel spray type burner and prevent the flame from coming into contact with the wall surface of the combustion chamber.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a configuration in which a flame is generated in the combustion chamber by a burner provided at the upper portion of the substantially cylindrical combustion chamber, and the burner has a plurality of nozzles spraying liquid fuel toward the end of the combustion chamber. A burner air outlet is provided at the peripheral edge of the burner to blow combustion air into the combustion chamber. During low combustion, the fuel sprayed from only the low combustion nozzle and the combustion air are mixed and burned. was carried out, at the time of high fire a burner for performing combustion by mixing a combustion air spray fuel from a plurality of nozzles, the low combustion nozzle is provided to be inclined to the combustion chamber central axis, said nozzle The inclination angle is such that the mixing point of the fuel sprayed in a conical shape from the nozzle and the combustion air sprayed in the downward direction from the combustion air outlet provided on the peripheral edge of the burner is close to the nozzle. Combustion sky And spout in combustion air spout in the side away from the nozzle, a burner to prevent the deviation of the flame, wherein a distance from the combustion air spout tip is set to be substantially equal.
[0008]
According to a second aspect of the present invention, in the burner for preventing the bias of the flame, a plurality of nozzles are provided so as to be inclined in the direction of the center axis of the combustion chamber, respectively. It is a burner to prevent.
[0010]
According to the present invention, since the spray direction of the fuel sprayed from the nozzle is inclined toward the central axis side of the combustion chamber, the fuel entry angle with respect to the air flow ejected from the combustion air outlet on the side far from the nozzle is The angle is greater than the angle when the nozzle is provided vertically, and conversely, the fuel entry angle with respect to the air flow ejected from the combustion air outlet near the nozzle is shallower than when the nozzle is provided vertically. Become. In other words, the mixing position of the air flow and the sprayed fuel ejected from the combustion air outlet far from the nozzle changes in the direction approaching the burner tip, and the air flow ejected from the combustion air jet near the nozzle The mixing position of the atomized fuel changes in a direction away from the burner tip. By eliminating the difference in the distance from the burner tip to the position where the fuel and combustion air are mixed, the flame does not spread greatly to one side, and the flame does not contact the combustion chamber wall surface.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. 1 is a partial cross-sectional view of the boiler, FIG. 2 is a partial cross-sectional perspective view of the burner portion extracted from FIG. 1, and FIG. 3 is a bottom view of FIG. The boiler has a combustion chamber 6 in the center, and surrounds the periphery of the combustion chamber 6 with an annular combustion chamber wall surface 10 made up of a number of water tubes. The combustion chamber 6 has a substantially cylindrical shape, and the burner 1 is provided above the combustion chamber 6. The burner 1 generates a downward flame toward the combustion chamber 6. The burner 1 has a double cylinder composed of an inner cylinder 2 and an outer cylinder 3, a low combustion nozzle 4 and a high cylinder in the inner cylinder 2. A combustion nozzle 5 is provided. The inner cylinder 2 and the outer cylinder 3 are concentric cylinders, and a diffuser provided with a combustion air outlet 7 at the tips of the inner cylinder 2 and the outer cylinder 3 is provided. The combustion air jets 7 are arranged at equal intervals at positions on the circumference of the burner center axis having a circular center, and jet combustion air from the combustion air jets 7 downward.
[0012]
The burner 1 is provided in the center of the upper part of the combustion chamber, and is installed so that the central axis of the combustion chamber and the central axis of the burner overlap. A nozzle adapter 8 is provided in the inner cylinder 2, and the low combustion nozzle 4 and the high combustion nozzle 5 are installed side by side on the nozzle adapter 8. The bottom surface of the nozzle adapter 8 is inclined so that the center is concave, and the low combustion nozzle 4 and the high combustion nozzle 5 are arranged in the direction of the central axis of the combustion chamber by threading perpendicularly to the inclined surface. Inclined to.
[0013]
The burner controls combustion at three positions of high combustion, low combustion, and stop, and in the case of low combustion, fuel is sprayed only from the low combustion nozzle 4 by supplying fuel only to the low combustion nozzle 4. In the case of high combustion, fuel is sprayed from both the low combustion nozzle 4 and the high combustion nozzle 5 by supplying fuel to the low combustion nozzle 4 and the high combustion nozzle 5. Also, the supply amount of combustion air is adjusted according to the combustion amount.
[0014]
Since the low combustion nozzle 4 and the high combustion nozzle 5 are installed so as to be inclined from the vertical to the center axis of the combustion chamber, the fuel sprayed from the low combustion nozzle 4 and the high combustion nozzle 5 inclines the nozzle. The amount of spraying is sprayed toward the central axis. The fuel sprayed from the low combustion nozzle 4 spreads out from the low combustion nozzle 4 in a conical shape, but since the fuel spray direction is inclined, the fuel sprayed out from the combustion air outlet far from the low combustion nozzle 4 The angle at which the atomized fuel enters the air flow becomes deeper than when the nozzle is provided vertically, and conversely, the atomized fuel enters the air flow ejected from the combustion air outlet near the low combustion nozzle 4. The angle is shallower than when the nozzles are provided vertically. If the fuel approach angle toward the air flow becomes deeper, the mixing position of the fuel and air flow will change in a direction approaching the burner tip, and conversely if it becomes shallower, the mixing position of the fuel and air flow will move away from the burner tip. Will change direction. The difference in the distance from the burner tip to the position where the fuel and combustion air are mixed can be eliminated, and the flame does not spread greatly to one side, so that the flame does not contact the combustion chamber wall surface.
[0015]
The inclination angle of the low combustion nozzle 4 is injected directly downward from the fuel sprayed in a conical shape from the low combustion nozzle 4 and from the combustion air jet 7 provided around the low combustion nozzle 4. Combustion air mixing points are the combustion air outlet 7 on the side close to the low combustion nozzle 4 and the combustion air outlet 7 on the side far from the low combustion nozzle 4 from the front end of the combustion air outlet. By setting so that the distances of the fuel and air are substantially equal, the difference in distance to the fuel and air mixing position cannot be made depending on the location in the burner.
[0016]
Since the combustion air is ejected from the combustion air jet 7 at the peripheral edge of the burner directly downward, the fuel and the combustion air are below the combustion air jet 7 and slightly from the tip of the combustion air jet. Mix at a remote location. When the fuel is sprayed from the low combustion nozzle 4 in a conical shape in the direct downward direction, the fuel and air mixing location becomes farther from the burner tip as the distance between the low combustion nozzle 4 and the combustion air outlet 7 increases. For this reason, the difference in the distance from the burner tip to the position where the fuel and combustion air are mixed is increased, and the flame is greatly spread to one side. However, by tilting the nozzle, it is possible to reduce the difference in distance from the tip of each combustion air outlet 7 to the position where the fuel and combustion air are mixed. The fuel sprayed in a conical shape starts to combust at approximately the same time, and if it does not start combusting partly early, the flame 9 does not spread greatly to one side and the flame 9 combusts. There is no contact with the chamber wall surface 10.
[0017]
In the case of high combustion, the amount of combustion air supplied to the combustion chamber 6 is larger than that during low combustion, and the opening area of the combustion air outlet 7 is constant. Only the air flow rate increases. When the flow velocity of the combustion air is increased, the mixing property of the fuel and the combustion air is improved, and the time required for the completion of the combustion is shortened because the progress speed of the combustion is increased, so that the spread of the flame is reduced. Therefore, depending on the conditions, only the low combustion nozzle 4 can be inclined toward the center of the combustion chamber, and even if the high combustion nozzle 5 remains vertical, it is possible to prevent the flame from coming into contact with the wall surface of the combustion chamber.
[0018]
In this embodiment, the number of nozzles for spraying fuel is two, but the same is true for three or more nozzles. If there are two nozzles, it will incline toward the other nozzle, and if there are three nozzles, it will incline toward the middle point of the other nozzle, but in terms of inclining toward the central axis of the combustion chamber, It will be the same.
[0019]
【The invention's effect】
By implementing the present invention, the flame does not come into contact with the combustion chamber wall surface, the combustion chamber wall surface is not overheated, and the unburned portion of the fuel does not adhere to the combustion chamber wall surface, resulting in incomplete combustion. You can get rid of it.
[Brief description of the drawings]
1 is a partial cross-sectional view of a boiler in an embodiment of the present invention. FIG. 2 is a partial cross-sectional perspective view of the burner portion extracted from FIG. 1. FIG. 3 is a bottom view of FIG. Partial cross-sectional view of [Symbols]
DESCRIPTION OF SYMBOLS 1 Burner 2 Inner cylinder 3 Outer cylinder 4 Low combustion nozzle 5 High combustion nozzle 6 Combustion chamber 7 Combustion air outlet 8 Nozzle adapter 9 Flame 10 Combustion chamber wall surface

Claims (2)

A flame is generated in the combustion chamber by a burner provided at the upper part of the substantially cylindrical combustion chamber. The burner is provided with a plurality of nozzles for spraying liquid fuel in a divergent manner toward the combustion chamber. Is equipped with a combustion air outlet that ejects combustion air into the combustion chamber. During low combustion, the fuel sprayed from only the low combustion nozzle and combustion air are mixed and burned. A burner that mixes fuel sprayed from combustion with combustion air and burns, wherein the low combustion nozzle is inclined toward the central axis of the combustion chamber, and the inclination angle of the nozzle is conical from the nozzle. The mixing point of the fuel sprayed on the burner and the combustion air jetting in the direction directly below from the combustion air jet provided on the peripheral edge of the burner is from the combustion air jet on the side close to the nozzle and the nozzle. Distant Burner to prevent the combustion air spout in the side, the deviation of the flame, wherein a distance from the combustion air spout tip is set to be substantially equal. The burner according to claim 1, wherein a plurality of nozzles are provided so as to be inclined in the direction of the central axis of the combustion chamber.

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