JP2003172505A - Method of internal mixture type high pressure air flow spray combustion and oil burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the combustibility with a NOx value satisfying a reference value, to reduce the quantity of soot, to increase the quantity of spray steam while preventing a sharp increase of NOx, and also to increase the range of the turn-down. <P>SOLUTION: The burner has a swirler and a nozzle with a main spout 1 and a sub spout 2. Fuel is sprayed in tow stages of a main fuel jet 6 made of a cone-shaped thin film annular jet for shielding swirling combustion air and a sub fuel jet 7 made of a cone-shaped thin film annular jet flowing along the main fuel jet 6 inside the main fuel jet 6 without penetrating the main fuel jet 6, while combustion air from a burner tile is being blown out in a swirl. Thin film main flame is formed with the main fuel jet 6 and the swirling combustion air to burn the fuel in the super air excessive state, and the sub fuel is burned with the combustion air with a low oxygen concentration which has passed the main flame so that the oxygen is partly consumed. Then a sub flame made of reducing flame is formed and the NOx produced by the main flame is reduced. At the time, the sub flame is completely burned with the oxygen remaining in the combustion air penetrating the main flame in the downstream. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal mixing type high pressure air flow spray combustion method and an oil burner in which liquid fuel such as heavy oil is atomized using an atomizing medium and burned. More specifically, the present invention relates to an internal mixing type high pressure air flow atomization type combustion method and an improvement capable of suppressing NOx and dust in an oil burner.

[0002]

2. Description of the Related Art Generally, liquid fuel represented by heavy oil is
Since it burns after being vaporized or decomposed, it is atomized into a large number of small oil droplet groups by various atomizers to facilitate gasification, stabilize ignition, and improve mixing with air for combustion ( This combustion method is called spray combustion). In this combustion method, several processes such as evaporation of oil droplets during spraying, diffusion of steam, mixing with ambient air, and combustion of a mixed gas generated thereby are in progress at the same time with mutual influence. Therefore, in spray combustion, it is necessary to promote atomization of oil and mixing with combustion air. However, even if the oil is atomized, it is inevitable that the combustibility deteriorates unless the combustion air can be taken in successfully.

Therefore, conventionally, in oil burners, atomization of oil is performed by using atomization medium (steam or air). Among them, an internal mixing type high-pressure airflow (spray) type burner is generally used, which mixes oil and atomizing medium in a mixing chamber in the nozzle and then ejects from the nozzle. According to this burner, the mixed fluid of oil and atomizing medium is ejected from the nozzle and at the same time expands and self-explodes to be atomized, so that diffusion and mixing with combustion air is excellent and stable flame formation can be expected.

Therefore, in the conventional oil burner, for example, as shown in FIG. 6, fuel is radially injected from a large number of small injection holes, for example, about 36 small injection holes to form an annular jet, and the surrounding area is formed. It is made to collide so as to be orthogonal to the flow of the flowing combustion air and mixed to form a thin film bell-shaped flame. In the case of this burner, the fuel spreads in a thin bell-like shape due to the balance between the injection speed of the fuel injected as a radially thin layer and the injection speed of the combustion air that is orthogonal to it, forming a flame, which results in stable combustion. The amount of soot and dust is also small. Therefore, in order to meet the required regulation value of NOx, the amount of steam is reduced to the extent that soot and dust are not generated while NOx is lowered, and the mixing with air is controlled.

Further, as shown in FIG. 7, there is also a burner of a system in which combustion air is divided and supplied. This burner has a middle cylinder with a fuel injection nozzle arranged in the center and a swirler around it inside the burner tile, and the combustion air is swirled through the middle cylinder swirler to be injected and the middle cylinder and burner. It is divided into two streams, a stream directly injected into the furnace from between the tiles. In the case of this burner, the combustion air swirled by the swirler and the injected fuel are mixed immediately after the injection to ensure the stability of the flame, and after that, complete combustion is performed by the secondary air supplied from around the flame later. Two-stage combustion (delaying combustion)
Is achieved to reduce NOx.

As another example of the two-stage combustion of combustion air, there is a burner of the type in which secondary air is directly injected into the furnace and blown against the flame shell as shown in FIG. . This burner is often used in large boilers.

There is also a burner of the two-stage combustion type of fuel. As shown in FIG. 9, this burner arranges a primary fuel nozzle in a burner throat for injecting combustion air, and a secondary fuel nozzle around a burner tile to diffuse a part of fuel with combustion air. The fuel is injected while being mixed, and a part of the fuel is injected from around the flame.

Further, there is a divided flame type burner. As shown in FIG. 10, this burner has a large number of injection ports of the fuel injection nozzle to reduce the number of the fuel injection nozzles and to create several completely divided flames, thereby suppressing interference between the flames and making the flames more intense. NO of the flame temperature is suppressed by making the cooling and combustion delay of the
The generation of x is suppressed.

[0009]

However, the burner (1) has NOx when the amount of spray vapor is increased to improve combustion.
Has a problem of becoming high. Further, there is a problem that the amount of soot and dust increases when trying to reduce NOx. Further, if the speed is not properly controlled, a bell shape cannot be generated and combustion becomes unstable. Further, when the water pipe is used in a boiler or the like arranged around it, heat exchange with water flowing in the water pipe lowers the flame temperature at a relatively early stage to lower NOx, but the water pipes around In a combustion furnace or the like that is not arranged, there is a problem that the flame temperature does not decrease early and NOx increases. Further, according to the burner, since the flame tends to have a relatively narrow angle and the flame temperature tends to be high, NOx becomes high when the amount of atomized steam is increased to improve combustion.
There is a problem that the amount of soot and dust increases when the amount of atomized vapor is reduced to reduce NOx. Further, according to the burner (1), although the NOx reduction effect is small despite having a complicated structure, it has the same problem as the burner (1). Further, according to the burner, there is a problem that a large amount of soot dust is generated despite the NOx reduction effect. Further, according to the burner, although the flame is cooled by the air, the combustion air penetrates between the flames, so that the mixing property is deteriorated and the oxygen concentration is not lowered, so that the NOx reducing effect is small.

All of the burners have a relationship in which soot and dust increase when combustion is suppressed, and NOx is reduced at the expense of combustibility. Normally, when the amount of steam is reduced (atomization is delayed), atomization becomes worse, so NOx is reduced, but soot is increased. Therefore, in the conventional internal mixing type high-pressure airflow spray combustion method and oil burner, the amount of steam is reduced so as to be below the standard (150 ppm) and combustion is performed.

It is an object of the present invention to provide a burner which has good combustibility, satisfies the standard value of NOx value, and has a small amount of soot and dust. Another object of the present invention is to provide a burner that does not cause a rapid increase in NOx even if the amount of spray vapor is increased. A further object of the present invention is to increase the width of turndown.

[0012]

In order to achieve the above object, the invention according to claim 1 mixes fuel oil and atomized fluid in a mixing chamber and then ejects them from a nozzle to expand and self-explode the fuel oil. In a spray combustion method of atomizing and combusting air, the combustion air is swirled and ejected from the burner tile, while a main fuel jet consisting of a conical thin film annular jet that blocks the swirl combustion air and a downstream of the main fuel jet. Inside the main fuel jet, the fuel flows along the main fuel jet, and the fuel is sprayed in two stages, a sub fuel jet consisting of a conical thin film annular jet that does not penetrate the main fuel jet, and swirls with the main fuel jet. Combustion air and excess air are burnt in an excess of air to form a thin film main flame, and at the same time, a part of the combustion exhaust gas with low oxygen concentration that has passed through the main flame burns an auxiliary fuel to form a reducing atmosphere and form a main flame. Is generated And so as to further complete combustion of the auxiliary fuel in a combustion exhaust gas by burning of the main fuel in the downstream as well as reducing the NOx.

This internal mixing type high pressure airflow spraying type combustion method is realized by, for example, an internal mixing type high pressure airflow spraying oil burner according to the present invention. According to a second aspect of the present invention, in a high-pressure oil burner in which fuel oil and atomized fluid are mixed in a mixing chamber and then jetted from a nozzle to expand and atomize the fuel oil by self-explosion, the inside of a burner tile around the nozzle is A swirler that gives swirl to the flowing combustion air, a main nozzle that forms a main fuel jet consisting of a conical thin film annular jet at the nozzle, and a flow inside the main fuel jet along the main fuel jet and penetrating the main fuel jet. Initial combustion in super-air excess state with main fuel composed of thin film annular jet injected from the main nozzle and swirling combustion air The main flame is stably formed, and the supply of fresh air to the auxiliary fuel is cut off by the main flame to cause the reduction combustion of the auxiliary fuel with a part of the combustion exhaust gas having a low oxygen concentration to generate NOx generated in the main flame. Is reduced And so as to complete combustion further sub fuel in the combustion exhaust gas was of not burn the main fuel in the downstream.

Therefore, according to the internal mixing type high-pressure airflow spraying combustion method and the oil burner according to the first and second aspects, the flow of the swirling combustion air is blocked by the main fuel that spreads in a thin film, so that the swirling combustion air is mainly used. Since the fuel is well mixed and burned on the surface of the main fuel jet without penetrating the fuel membrane, the initial combustion is promoted, and the combustion state of the main flame can be made good and stable. That is, since the combustibility is very good, the width of turndown can be widened (for example, about 10: 1 or more).

Further, since the main flame blocks the flow of combustion air, it is difficult for the air of the main flame to enter the inside. Moreover, oxygen is consumed when the combustion air penetrates the main flame. For this reason,
Inside the main flame, the auxiliary fuel that contacts the inner surface of the main flame causes reduction combustion (generation of the reduction zone) when the residual oxygen amount is too small to reduce the NOx generated in the main flame and reduce it. On the other hand, the combustion of the sub-flame itself does not proceed, so it is difficult to generate thermal NOx in the sub-flame. Moreover, this reducing combustion prevents negative pressure in the main flame and prevents the flame from shrinking. As a result, the opening angle of the main flame can be maintained, so that it is possible to prevent the flame from shrinking and the flame temperature becoming high.

Further, the secondary flame is mixed downstream with the main flame with the combustion exhaust gas obtained by burning the main fuel to cause complete combustion. At this time, since the main flame is present as a type of flame, secondary combustion is stably generated, and the auxiliary fuel, which has not progressed in combustion, is combusted, and is completely combusted as a whole. As a result, complete combustion is achieved as a whole, and soot generation is small.

According to a third aspect of the present invention, in the internal mixing type high-pressure air flow atomizing oil burner according to the second aspect, an orifice is provided in the header portion of the auxiliary injection hole, and a mixed fluid of fuel oil and atomized fluid is provided. The injection pressure is less than that of the main injection hole. In this case, in addition to the area ratio of the main injection hole and the sub injection hole, the pressure of the fuel applied to the sub injection hole is reduced by the pressure reducing action of the orifice, and the penetration force is suppressed, so that the sub fuel can penetrate the main flame. There is no.

According to a fourth aspect of the present invention, in the internal mixing type high pressure gas spray type oil burner according to the second or third aspect, the adjoining angle of the main injection hole is in the range of 10 to 14 °. . In this case, a thin-film main fuel jet is reliably formed.

According to a fifth aspect of the present invention, in the internal mixing type high pressure air flow atomizing oil burner according to any one of the second to fourth aspects, the nozzle injection of the auxiliary injection hole with respect to the nozzle injection angle of the main injection hole is performed. The angle is slightly narrowed. In this case, even if the main fuel completes combustion and loses its injection momentum, the auxiliary fuel does not penetrate the main flame.
If the same angle or the nozzle injection angle of the auxiliary injection hole is wider, the injection momentum becomes larger in the unburned auxiliary fuel jet than in the main flame that completes combustion and loses injection momentum. Secondary fuel may penetrate the flame.

Further, the invention according to claim 6 is the internal mixing type high pressure air flow atomizing oil burner according to any one of claims 2 to 5, wherein the main fuel jet is between the opening of the burner tile and the swirling combustion air. It is formed at a position where a slight gap is formed so that the water can flow out. In this case, since it is mixed with air at the root portion of the main fuel jet that is formed in a thin film with a spread that blocks the flow of combustion air, the initial combustion at the root portion of the flame is promoted, and combustion of the main flame is promoted. It can be in good condition and stable.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described below in detail based on the embodiments shown in the drawings.

1 and 2 show an embodiment of the oil burner of the present invention. This oil burner burns liquid fuel, particularly oil fuel such as C heavy oil, and atomization fluid such as oil and steam or air (also called atomization medium).
Is an internal mixing type oil burner (internal mixing type high pressure spraying burner) which is sprayed after being mixed under uniform pressure. This burner pumps oil and atomizing fluid to the nozzle tip 8 at the tip of the nozzle 9 at a uniform pressure of, for example, 1 to 5 kg / cm ² ,
After being mixed in the mixing chamber 3 in the nozzle tip 8 and then ejected from the two types of injection holes 1 and 2, it is mixed with the combustion air flowing around the nozzle 9 and burned.

The combustion air is strongly swirled by a swirler 11 arranged around the nozzle 9, and when jetted from the burner tile 10, the main fuel jet consisting of a conical thin film annular jet that blocks the swirling combustion air. And a sub-fuel jet consisting of a conical thin-film annular jet that flows along the main fuel jet inside the main fuel jet downstream of the main fuel jet and does not penetrate the main fuel jet. It mixes with the fuel being formed to form a primary flame and a secondary flame. Here, the mixed fluid of the oil and the atomizing fluid is ejected from the internal mixing nozzle and at the same time expands and self-explodes to atomize, thereby forming a stable main flame that is well diffused and mixed with the combustion air. Moreover, it becomes difficult for the combustion air given the swirl to penetrate the thin-film-shaped main fuel jet that spreads in front of it, and the combustion air comes into contact with the main fuel to complete combustion on the surface. Further, the main fuel jet and the swirling combustion air form a thin film main flame and burn in an excessive air excess state, and the auxiliary fuel is burned by the combustion air having a low oxygen concentration that has passed through the main flame and partially consumed oxygen. A secondary flame composed of a reducing flame is formed to reduce NOx produced in the main flame, and the secondary flame is completely burned by oxygen remaining in the combustion air that has penetrated the main flame downstream.

In the present embodiment, the combustion air is introduced into the burner tile 10 through the wind box 14 into the first air register 15 and the second air register 16.
And give a turn in advance. The first air register 15 and the second air register 16 give mutually opposite swirl to the introduced combustion air. For example, the first air register 15 is provided so as to swirl the combustion air counterclockwise toward the opening 13 of the burner tile 10, and the second air register 16 is provided so as to swirl the combustion air clockwise. The first air register 15 is arranged inside (smaller in diameter) than the second air register 16, and
The reverse swirl flow of the combustion air is formed inside the swirl flow of the combustion air formed by the air register 16. Therefore, an annular vortex is formed at the boundary between the outer swirl flow and the inner swirl flow, and it is possible to uniformly contact the main fuel and generate a good air-fuel mixture. Here, if the swirling force is excessively applied to the combustion air only by the first and second air registers 15 and 16, the air is gathered on the outer side due to the influence of the centrifugal force, and the inner side is diluted, so that it is opened by 50%. Degree
The air is put inside and the turning force is given to the outside air. Then, the swirler 11 is arranged immediately in front of the main injection hole 1 so as to give a swirling force of a rotation reverse to that of the first air register 15 so as to give a rectified swirling flow without light and shade. Here, as the swirler 11, for example, an axial flow 50
%, A swirling flow of about 50% is used.

Further, the outlet spread angle of the burner tile 10 is set to about 18 °, which is narrower than usual, and the swirling combustion air is prevented from spreading and collected at the root of the burner (near the jet hole of the main jet hole 1). The initial combustion is done at the outlet. Reference numeral 12 in the drawing is a furnace body.

As shown in FIGS. 3 and 4, the internal mixing nozzle has two types of injection holes 1 and 2 in the mixing chamber 3 portion, that is, a main injection hole 1 group and a sub injection hole 2 group. Prepared by arranging them in the front-back direction. The group of main injection holes 1 and the group of auxiliary injection holes 2 are annularly arranged around the nozzle axis O ₁ and are forward of the group of main injection holes 1 (that is, ejected from the group of main injection holes 1). The sub-injection hole 2 is formed so that the sub-fuel is ejected inside the main flame 6 formed of the fuel.
The group of is arranged. The main injection holes 1 have a constant pitch so that the injection axis O ₂ intersects the nozzle axis O ₁ and injects a mixed fluid of thin-film fuel oil and atomizing fluid that spreads conically toward the front of the nozzle. It is perforated in an annular shape. For example, in the case of this embodiment, a large number of jets are included so that the nozzle jetting angle (also referred to as full angle) θ ₁ is about 90 to 100 ° and the adjacent angle (angle between adjacent nozzles) is 10 to 14 °. By forming the hole 1 in an annular shape, a conical thin film annular jet that blocks combustion air flowing around the nozzle is formed.

[0027] The next angle theta ₃ main nozzle hole 1, to form a wide flame thin, nozzle injection angle theta ₁ it is necessary to obtain a wide angle, while increasing the number of holes to reduce the nozzle hole diameter , 11 ° is preferable.

Further, a large number of sub injection holes 2 on the front side of the main injection hole 1 are slightly narrower than the main injection hole 1, and the nozzle injection angle θ _{2 is,} for example, 80 to 85 ° (may not be 95 °). The angle is preferably narrower than the full angle θ ₁ of the main injection hole 1 by about 5 °. At this time, the main injection hole 1 and the sub injection hole 2 in front of it have the same nozzle injection angle (θ ₁ =
θ ₂ ), or the nozzle injection angle θ ₂ of the auxiliary injection hole 2 is formed to be slightly smaller than the nozzle injection angle θ ₁ of the main injection hole 1 (θ ₁ > θ ₂ ). It is provided so that the auxiliary fuel does not penetrate the main flame. The main injection hole 1 is formed as a small hole because the synthetic jet becomes a thin film.

The nozzle injection angle θ ₁ of the main injection hole 1 at this time
Is appropriately changed according to the size and shape of the combustion chamber in which the burner is mounted, the nozzle arrangement position in the burner throat 10, and the like. In the case of a relatively elongated combustion chamber, the nozzle injection angle θ ₁ is When it becomes small, and the width is relatively wide and the depth is short, the nozzle injection angle θ ₁ becomes large, and the nozzle arrangement position differs depending on whether it is near the opening of the burner throat or at the back side. It is not preferable to move the position of the nozzle forward to bring it closer to the opening of the burner tile 10, because it may be greatly affected by radiation from the inside of the furnace or may be too far from the ignition burner to cause ignition problems. Therefore, as in the burner of the embodiment of FIG. 1, the main fuel jet injected at the opening 13 of the burner throat 10 has a main fuel jet opening 1 of the burner tile 10.
When it is formed at a position where a slight gap can be generated between the swirling combustion air and the nozzle 3, the nozzle injection angle θ ₁ is preferably in the range of 90 ° to 100 °. From the relationship between the nozzle injection angle θ ₁ and the flame length,
If it is less than 90 °, it causes the increase of soot and dust due to poor combustion due to poor mixing due to the decrease of the specific surface area, and if it exceeds 100 °, unburned oil directly hits the burner tile and causes carbon adhesion or oil dripping. It is because
It is preferable that the nozzle injection angle θ ₁ has a wide angle so that the fuel oil becomes a heavy oil that is difficult to atomize.

At least in the main fuel jet, a large number of small injection holes are arranged on the circumference in the range of adjacent angles of 10 to 14 °, preferably about 11 °, so that the jets interfere with each other immediately after the injection and have a conical shape. It is provided so as to form a film-like jet that opens to the open. The diameter ratio of the main injection hole 1 and the sub injection hole 2, that is, the flow rate ratio, is preferably determined in view of the conditions for achieving the two-stage fuel combustion within a range not exceeding 80 to 90:20 to 10. , For example, about 80:20. Since the influence of the injection angle θ on the combustibility cannot be ignored, it is desirable to set the respective diameters so that the combined jet forms a predetermined combined injection angle θ in the state where the jet collision effect is obtained. Therefore, as shown in FIG. 3, the header portion 5 of the sub injection hole 2 is provided with an orifice 4 to reduce the pressure so that the injection pressure of the mixed fluid of the fuel oil and the atomized fluid is made lower than that of the main injection hole 1. I have to. This prevents the sub fuel jet (sub flame) 7 from penetrating the main fuel jet (main flame) 6.

In the burner constructed as described above, the mixed fluid of oil and steam mixed in the mixing chamber 3 of the internal mixing type nozzle has a group of main injection holes 1 consisting of a large number of small holes. When it is injected from the group of the secondary injection holes 2 and is atomized by the expansion self-destruction, this jet flow is further interfered with the jet flows ejected from the adjacent injection holes to be expanded and it is easy to take in combustion air. The film jet is formed into a film jet having a much larger specific surface area than the circular jet. Therefore, even with oil fuel, a combustion state similar to the diffusion combustion state of gas fuel can be realized.

Combustion air forcibly swirled by a swirler or the like collides therewith to stably form a main flame. The main flame is mixed by interrupting the flow of the swirling combustion air with a thin-film fuel jet having a large specific surface area, thereby completing the initial combustion well. On the other hand, in the main flame, the auxiliary fuel injected from the auxiliary injection hole group undergoes reductive combustion with a part of the combustion exhaust gas that has passed through the main flame. The combustion exhaust gas, which has consumed oxygen and has a low oxygen concentration when passing through the main flame, burns a secondary fuel to form a reducing atmosphere to reduce NOx generated in the main flame and also to generate a negative atmosphere in the main flame. It is possible to prevent the flame from shrinking due to pressure, and to maintain the opening angle of the main flame. Further downstream, the unburned auxiliary fuel comes into contact with the combustion exhaust gas from which the main fuel has been burned, and is completely burned.

Here, the flow of the combustion air is cut off by a main fuel jet consisting of a thin film annular jet that spreads in a conical shape, and is mixed with the main fuel near the opening of the burner throat to form a main flame. Immediately after the injection, the auxiliary fuel injected inside does not contact. Even if a part of the combustion air penetrates the main flame and enters the inside of the main flame, oxygen is used to contact the auxiliary fuel in a low oxygen state while passing through the main flame. Therefore, the auxiliary fuel injected into the main flame produces a reducing flame to reduce NOx in the main flame on the inner surface of the main flame. That is, as a result of the primary combustion, the residual O ₂ concentration on the inner surface of the main flame is extremely reduced, and subsequently, the auxiliary fuel injected inside the main flame first comes into contact with the thin O ₂ thin film combustion gas. Therefore, a rapid oxidation reaction is suppressed, and at the same time, a partial NOx reduction reaction is promoted. After that, the unburned auxiliary fuel and the combustion air that has passed through the main flame spread into the furnace, contact and are mixed in the downstream of the main flame, and burn.

The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the swirling force is applied to the combustion air using the first and second air registers 15 and 16 and the swirler 11, but the swirling force is not particularly limited to this, and in some cases only the swirler 11 is used. You may make it obtain desired swirling combustion air. Further, in the present embodiment, the one in which oil fuel is mainly burned has been described, but the present invention is not particularly limited to this, and the invention can be applied to a gas burner. In this case, the jet of gas fuel is expanded by the jet collision and it is easy to take in the combustion air, and it is changed to a thin and wide film jet without a gap, and the specific surface area is dramatically increased. The injection speed can be prevented from decreasing and the effect of lowering the pressure inside the flame can be eliminated. Therefore, high load combustion in a narrow space is possible. In particular, when used in a gas turbine combustor, even if the swirler is not used to forcibly swirl the combustion air, the injected gas fuels collide with each other to form a thin-film synthetic jet with a large specific surface area. While taking in the surrounding combustion air into the flame,
This is advantageous because a large jet divergence angle can be formed by jet synthesizing and the synthetic jet angle can be maintained to prevent flame constriction. Further, when the oil burner of the present invention is applied as a combustor of a water tube boiler, the main flame, which completes the initial combustion and becomes high temperature, is absorbed by the water tubes around it at an early stage and the flame is cooled, so NOx Is small.

[0035]

[Examples] (Example burner) Burner tile 18 ° angle swirler 14 blades (opening angle 45 °) Nozzle main injection hole 24 holes, full angle (90 °) arrangement, adjacent angle 11 ° sub injection hole 20 holes, full angle ( 85 °) arrangement, adjacent angle 11 ° (nozzle hole area ratio of main injection hole and sub injection hole is 83: sub 1
7, the auxiliary nozzle hole header part is equipped with a fixed orifice, so that the auxiliary nozzle hole area is used in the range of 10 to 17%, and the area ratio between the main nozzle hole and the auxiliary nozzle hole is variably adjusted. It was made possible. The diameter of the orifice 4 is determined so that the fuel injected from the auxiliary injection hole does not penetrate the main flame. ) Made a burner.

[0036] I made a burner.

Use these burners with Mcr. (Maximum continuous load factor) 1
Equipped with a 7t / h natural circulation type water tube type boiler, C heavy oil
(FN (containing nitrogen content) 0.2 wt% or less, C.R.
(Containing carbon content: 10 wt% or less) was burned. That conclusion
As a result, the results shown in FIG. 5 were obtained. That is, 4% O_Two
Concentration converted NOx value is below the standard value (150ppm) 13
0 ppm level, almost flat against load
It was. In addition, since the pressure difference is increased to improve the combustibility,
It is possible to reduce the NOx value. Also, the dust concentration is the standard
Value (0.25 mg / Nm^Three) Much less than 0.08 mg /
Nm^Three(4% O _TwoConversion). Also, 1250 to 1
I was able to turn down in a wide range of 20 l / h. According to
, When the load factor in factories decreases,
On / off operation of the car (operation that repeats ignition and extinguishing) is reduced
It will be possible to operate a little more efficiently,
Can be operated by combustion. Heat loss due to heat release when burner combustion is stopped
Therefore, it is possible to prevent deterioration of combustion efficiency.

[0038]

As is apparent from the above description, according to the internal mixing type high pressure air flow spray combustion method and the oil burner of the first and second aspects, the excess air exceeding the proper air ratio of the main fuel is greatly exceeded. NO in this main flame after burning in the state
Since x can be reduced by the auxiliary fuel, and then the high temperature combustion air and the auxiliary fuel can be mixed in the furnace to cause secondary combustion, the main flame is burned in the super air excess state and NO x In addition to suppressing the generation, NOx is further reduced by the reducing action of the secondary fuel, and further downstream, the secondary fuel completes the combustion by the low-oxygen concentration flue gas that has burned the primary fuel, resulting in complete combustion as a whole. As a whole, the generation of NOx can be significantly reduced as compared with the conventional one. Further, even if the amount of spray vapor is increased (atomization is promoted and combustibility is improved), there is no rapid increase in NOx. Moreover, the combustion state of the main flame is as good and stable as a low NOx burner, so the turndown ratio can be increased. Further, since the whole is completely burned and the generation of soot and dust can be prevented, the amount of soot and dust is much smaller.

Therefore, in the conventional burner, the amount of soot tends to increase when the NOx is kept within the regulation value. However, according to the burner of the present invention, the amount of soot and dust is sufficiently low and the amount of soot is also different in each stage. Get lower.

According to the third aspect of the present invention, not only the area ratio of the main nozzle and the sub nozzle but also the orifice is limited, so that the fuel injected from the sub nozzle is reduced, the penetrating power is lost, and the main flame penetrates. And the auxiliary fuel can be reliably cut off from the fresh air. Therefore,
The secondary flame can be reliably reduced and burned.

Further, according to the invention described in claim 4, it is possible to form a thin-film main fuel jet.

Further, according to the invention of claim 5, even if the main fuel completes combustion and loses its injection momentum,
Since the auxiliary fuel does not penetrate the main flame, the flame is not disturbed, and the two-stage fuel combustion can be made good and stable.

Furthermore, according to the sixth aspect of the present invention, since the main fuel jet formed in a thin film with a spread that blocks the flow of the combustion air is mixed with air at the root portion, the initial portion of the flame root portion Combustion is promoted, and the combustion state of the main flame can be made good and stable.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an oil burner that realizes an internal mixing type high-pressure airflow spraying combustion method of the present invention.

FIG. 2 is a front view of the burner shown in FIG.

FIG. 3 is an enlarged vertical sectional view of a nozzle tip portion.

FIG. 4 is a front view showing a half of the nozzle tip of FIG.

FIG. 5 is a graph showing a NOx emission amount when an internal mixing type high pressure airflow atomizing oil burner according to an embodiment of the present invention is burned.

FIG. 6 is a principle view of a conventional bell-type low NOx type oil burner.

FIG. 7 is a principle diagram of a conventional low NOx type oil burner of a two-stage combustion air supply system.

FIG. 8 is a principle view showing another example of a conventional low-NOx type oil burner of a two-stage combustion air supply system.

FIG. 9 is a principle diagram of a conventional low NOx type oil burner of a two-stage fuel supply system.

FIG. 10 is a principle view of a conventional split flame type low NOx type oil burner.

[Explanation of symbols]

1 Main injection hole 2 Sub injection hole 3 Mixing chamber 4 Orifice 5 Header part of sub injection hole 6 Main fuel jet 7 Sub fuel jet 8 Nozzle tip 9 Fuel nozzle 10 Burner tile 11 Swirler 13 Burner tile outlet θ ₁ Nozzle of main injection hole Injection angle θ ₂ Nozzle of secondary injection hole θ ₃ Adjacent angle of main injection hole O ₁ Nozzle axis O ₂ Main injection hole axis O ₃ Sub injection hole axis

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiji Matsui             6th, Omiya-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture             Engineering Co., Ltd.             Service Business Headquarters (72) Inventor Norihiko Koizumi             6th, Omiya-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture             Engineering Co., Ltd.             Service Business Headquarters F-term (reference) 3K023 EA02 EA09                 3K052 GA06 GC01 GC03 GD03 GE05                 3K056 AA06 AB01 AC01 AC03 AD01                       CA00 CB03 CB07                 3K065 TA01 TA04 TA12 TB01 TB02                       TB04 TD04 TH04 TH06 TH14                       TJ03 TJ06 TJ10 TP02

Claims (6)

[Claims] 1. A spray combustion method in which fuel oil and atomized fluid are mixed in a mixing chamber, and then sprayed from a nozzle to expand and atomize and burn the fuel oil by self-explosion. A main fuel jet consisting of a conical thin-film annular jet that ejects from the tile while blocking the swirling combustion air, and flows along the main fuel jet inside the main fuel jet downstream of the main fuel jet. A thin film of a conical thin film that does not penetrate the jet, and a sub fuel jet consisting of an annular jet that sprays the fuel in two stages and burns the main fuel jet and the swirling combustion air in an excess air state to form a thin film. Along with forming the main flame, the auxiliary fuel is combusted with a part of the exhaust gas having a low oxygen concentration that has passed through the main flame to form a reducing atmosphere to reduce NOx generated in the main flame. An internal mixing type high-pressure airflow spray combustion method characterized in that the auxiliary fuel is completely combusted with combustion exhaust gas obtained by combusting the main fuel downstream. 2. A high pressure oil burner that mixes fuel oil and atomizing fluid in a mixing chamber, then ejects from a nozzle to expand and atomize the fuel oil by self-explosion, and flows in a burner tile around the nozzle. A swirler that swirls the combustion air, a main nozzle that forms a main fuel jet consisting of a conical thin film annular jet in the nozzle, and a flow along the main fuel jet inside the main fuel jet A sub-injection hole forming a sub-fuel jet consisting of a conical thin-film annular jet that does not penetrate, and a super-fuel excess of swirling combustion air and the main fuel consisting of a thin-film annular jet injected from the main nozzle In this state, initial combustion is performed to stably form the main flame, and the main flame cuts off the supply of fresh air to the sub-fuel to cause a reduction combustion of the sub-fuel with a part of the combustion exhaust gas having a low oxygen concentration, Main flame An internal-mixing high-pressure air-stream atomizing oil burner characterized by reducing the NOx produced in 1. and completely burning the auxiliary fuel with the combustion exhaust gas obtained by burning the main fuel further downstream. 3. The internal mixing according to claim 2, wherein an orifice is provided in the header portion of the auxiliary injection hole so that the injection pressure of the mixed fluid of fuel oil and atomizing fluid is weaker than that of the main injection hole. Type high pressure air flow spray oil burner. 4. The internal mixing high-pressure airflow atomizing oil burner according to claim 2, wherein the adjacent angle of the main injection hole is in the range of 10 to 14 °. 5. The internal mixing type high-pressure airflow atomization type according to claim 2, wherein the nozzle injection angle of the sub injection hole is slightly narrower than the nozzle injection angle of the main injection hole. Oil burner. 6. The main fuel jet flow is formed at a position where a small gap is formed between the main fuel jet flow and the opening of the burner tile so that swirling combustion air can flow out. Internal mixing type high pressure air flow spray oil burner.