JPH08285223A - Method and device for nitrogen oxide low generating combustion - Google Patents

Abstract

PURPOSE: To recirculate own exhaust gas effectively before starting combustion to improve the reducing effect of NOx by a method wherein side fuel injection pipes are provided at both sides of slot type air injection units formed on a shielding plate, provided at the tip end of a fuel pipe, while auxiliary fuel injecting ports are provided in the axial direction of the fuel pipe. CONSTITUTION: A combustion device, employing own exhaust gas recirculating method, is provided with a fuel pipe 1, inserted into an air pipe 2, and a shielding plate 4, provided at the tip end of the fuel pipe 1 and provided with a plurality of slot type air injection units 3. A side fuel injection pipe 5, communicated with the fuel pipe 1, is provided at both sides of respective air injection units 3 while a side fuel injection unit 6 is provided at the side of the injection pipes 5. Further, fuel injection ports 14, injecting auxiliary fuel into the axial direction of the fuel pipe 1, are provided at the tip end of the fuel pipe 1 and a disc plate 7, having a large diameter, is provide at the upstream side of the injection ports 14 while fuel of 10-20% of total fuel is injected from the fuel injection ports 14 as auxiliary fuel. On the other hand, the ratio of the flow speed of air to the flow speed of fuel is specified to be 0.2 or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for low-nitrogen oxide generation combustion.

[0002]

2. Description of the Related Art Emission regulations for NOx generated by combustion are becoming stricter year by year, and technological development for reducing NOx is being actively conducted. NOx generated during combustion includes fuel NOx, prompt NOx, and thermal NOx.
It is said that among these, thermal NOx is generated by the oxidation of nitrogen molecular components in combustion air in a high temperature atmosphere, and has high temperature dependence,
The production amount rapidly increases as the combustion temperature increases.
Thermal NOx is always generated when a nitrogen molecule component is present in the combustion gas, and especially when the fuel is a hydrocarbon-based gaseous fuel, most of the NOx discharged is said to be thermal NOx, and many reductions are made. A method has been devised. For the purpose of reducing thermal NOx, combustion methods such as a multi-stage combustion method, an exhaust gas recirculation method and a lean combustion method have been devised, and many combustion methods combining several methods have been devised.

[0003]

The multi-stage combustion method is characterized in that fuel or combustion air is divided into two or more stages and burned, and low NOx is caused by a decrease in flame temperature or a decrease in oxygen concentration. It realizes combustion. In such a combustion method, there is a problem that the combustor becomes complicated because the combustion is performed in multiple stages. The exhaust gas recirculation method aims to lower the flame temperature and oxygen concentration by mixing a part of the combustion gas with the combustion air or fuel.The forced exhaust gas recirculation method and the self-exhaust gas recirculation method are used. It is roughly divided into. The forced exhaust gas recirculation method is the most general method in which a part of combustion gas is forcibly mixed with combustion air or fuel by using a recirculation duct and a blower. In the self-exhaust gas recirculation method, by devising a combustor and using the phenomenon that the surrounding gas is sucked into the jet flow, it is possible to mix the combustion gas with the combustion air flow and fuel flow to have the effect of exhaust gas recirculation As a feature, there is an advantage that the effect of exhaust gas recirculation can be obtained without forcibly recirculating the combustion gas. Further, there is no complexity of dividing fuel or combustion air into a plurality of systems unlike the multi-stage combustion method. As a combustor characterized by utilizing self-exhaust gas recirculation, there is, for example, JP-A-62-17506, and many other combustors use the self-exhaust gas recirculation method, but NOx reduction Has a limit, and further technological development is needed to comply with the recent severe NOx regulations. Therefore, as a combustion method making the most of the merit of the self-exhaust gas recirculation method, Japanese Patent Laid-Open No. 1-3010
3, Japanese Patent Laid-Open No. 3-91601 and Japanese Utility Model Laid-Open No. 52-61545. In these combustion methods, in order to maximize the effect of self-exhaust gas recirculation, the burner does not have a flame holding mechanism, and the combustion air flow and the fuel flow are separated and injected into the furnace independently. It is characterized by that. As a result, the flame is lifted and formed without being fixed to the burner, and a portion of the combustion gas in the furnace is sufficiently sucked into the fuel flow and the combustion air flow before combustion starts. In such a combustion method, the flame becomes a slow diffusion flame, but since it does not have a flame holding mechanism, it may not be able to be used unless the temperature of the combustion region is high in order to obtain stable ignition, a heating furnace, It is suitable for high-temperature furnaces such as melting furnaces, but when used for boilers and low-temperature heating furnaces, the problem is that the amount of unburned components increases and the furnace body must be enlarged for complete combustion. was there. There is also a method of using a premixed flame as a method of reducing thermal NOx. In premixed combustion, burning NOx with a high air ratio can significantly reduce NOx, but in high air ratio burning, excess air increases, resulting in a large decrease in combustion and heat transfer efficiency and stability of the premixed flame. There was a problem that it was inferior to. Then, as a method of reducing the thermal NOx by giving the effect of self-exhaust gas recirculation to premixed combustion, Japanese Patent Laid-Open No. 3-17
There is 5211. In such a combustion method, by adding a device to the flame stabilizer, before the premixed gas burns,
NOx is reduced by mixing a part of the low-temperature combustion gas with a premixed gas to reduce the flame temperature or reduce the oxygen concentration. In such a combustion method and combustion apparatus, since the premixed combustion is used, a mixer for producing the premixed gas is required, and since the premixed gas within the flammability limit is used, the flame is burned in the burner or mixed. There are problems common to premixed combustors, such as the danger of so-called backing when returning to the interior of the reactor. Also, since a part of the combustion gas is mixed with the combustible premixed gas, if the combustion gas to be mixed is at a high temperature, it will ignite as soon as the premixed gas mixes with the combustion gas, and the effect of self-exhaust gas recirculation will be improved. There is a problem that the flame stabilizer needs to be specially devised in order to mix the premixed air and a part of the combustion gas so that the premixed air does not ignite. As described above, the self-exhaust gas recirculation method has a merit that the combustion device is simple and low NOx combustion is possible as compared with other low NOx combustion methods such as the multi-stage combustion method and the lean premixed combustion method. have. Thermal N using self exhaust gas recirculation
In the combustion method aiming at the reduction of Ox, the problem that the furnace temperature range that can be used is limited and the usable combustion equipment is limited in the method that makes maximum use of the self-exhaust gas recirculation for the diffusion flame. There was a point. In addition, in the case of applying self-exhaust gas recirculation to the premixed flame, there is a problem of flame stability peculiar to the premixed combustor such as back combustion, and a special device is required for the flame stabilizer. was there.
Combustion technology that uses the self-exhaust gas recirculation method more effectively is desired in order to meet the increasingly stringent NOx regulations of the combustor and realize even lower NOx combustion. The object of the present invention has been made by paying attention to such a point, and while using diffusion combustion, self-exhaust gas recirculation is effectively performed before combustion starts, and even in a low temperature atmosphere. Provided are a nitrogen oxide low generation combustion method and a combustion apparatus which are excellent in flame stability.

[0004]

In order to solve the above-mentioned problems, the present invention provides a shield plate provided with a plurality of long-hole-shaped air jets on the outer periphery of the tip of a fuel pipe inserted in an air pipe, Cylindrical air flow forming air jets are formed on the edge of the shielding plate, and side fuel jets communicating with the fuel pipes are installed on both sides of the plurality of long hole air jets. The side portion of the pipe is provided with a side fuel jet portion for jetting fuel in the circumferential direction of the shield plate, the tip of the fuel pipe is projected from the shield plate, and the fuel is attached to the tip portion of the fuel pipe. A central axial fuel injection hole for ejecting auxiliary fuel is provided in the central axis direction of the pipe, and a disk plate larger than the fuel pipe is installed upstream of the central axial fuel injection hole to form the cylindrical air flow. The air is ejected from the elongated air ejector while the air is ejected from the air ejector. 10 to 2 of all the fuel from the fuel injection hole in the central axis direction while jetting fuel from both sides of the side fuel jetting portion at right angles to the air flow to mix and burn.
0% is injected as an auxiliary fuel in the direction of the central axis, and the combustion energy is burned with the combustion energy accompanied by the injection energy, and the air flow velocity at the elongated hole air ejection portion and the side fuel ejection portion The present invention provides a low-nitrogen oxide generation combustion method characterized in that a ratio of fuel flow rates is 0.2 or more.

Further, in order to solve the above-mentioned problems, the present invention installs a shield plate provided with a plurality of elongated hole-like air jetting portions on the outer periphery of the tip of the fuel pipe inserted into the air pipe, and shields the shield. Cylindrical air flow forming air jets are formed on the edge side of the plate, and side fuel jets communicating with the fuel pipes are installed on both sides of the plurality of long hole air jets. The side portion is provided with a side fuel jetting portion for jetting fuel in the circumferential direction of the shield plate, the tip of the fuel pipe is projected from the shield plate, and the fuel pipe is attached to the tip portion of the fuel pipe. A nitrogen oxide low characterized in that a central axial fuel ejection hole for ejecting auxiliary fuel is provided in the central axial direction, and a disc plate larger than the fuel pipe is installed upstream of the central axial fuel ejection hole. A generative combustion device is provided.

In order to solve the above-mentioned problems, according to the present invention, the shape of the central axial fuel injection hole is formed as a slit circular hole, and the ring-shaped fuel is ejected from the central axial fuel injection hole. The present invention provides a method for low-nitrogen oxide generation combustion, which is characterized in that the gas in the furnace is combusted while being mixed by wake mixing.

Further, in order to solve the above-mentioned problems, the present invention provides a low-nitrogen oxide combustion apparatus characterized in that the shape of the central axial fuel injection hole is a slit hole. .

In order to solve the above-mentioned problems, the present invention provides a swirl vane in a slit circular hole, ejects a swirling ring-shaped fuel from the slit circular hole, and circulates the gas in the furnace. The present invention provides a method for low-nitrogen oxide generation combustion, which is characterized by performing mixed combustion.

Further, in order to solve the above-mentioned problems, the present invention provides a low-nitrogen-oxide generation combustion apparatus characterized in that a swirl vane is provided in a slit circular hole.

In order to solve the above-mentioned problems, according to the present invention, a cylindrical air flow forming air jetting portion is constituted by providing an annular slit between an air pipe and a shield plate, and the annular slit is provided. The invention provides a nitrogen oxide low generation combustion method, characterized in that air is ejected in a cylindrical shape to burn.

Further, in order to solve the above-mentioned problems, the present invention is characterized in that the cylindrical air flow forming air jetting portion is constituted by providing an annular slit between the air pipe and the shield plate. The present invention provides a low-nitrogen oxide combustion device.

In order to solve the above-mentioned problems, according to the present invention, the cylindrical air flow forming air jetting portion is constituted by arranging a large number of small holes in a ring shape inside the edge of the shield plate. It is intended to provide a nitrogen oxide low generation combustion method, characterized in that air is jetted from a large number of small holes and burned.

Further, in order to solve the above-mentioned problems, the present invention is configured such that the cylindrical air flow forming air jetting portion is formed by arranging a large number of small holes annularly inside the edge of the shield plate. The present invention provides a low-nitrogen oxide generation combustion device characterized by the above.

In order to solve the above-mentioned problems, according to the present invention, the area of the air ejecting portion for forming a cylindrical air flow is set to 20% or less of the total air introduction area for combustion. The present invention provides a method for low-nitrogen oxide generation combustion characterized by the above.

In order to solve the above-mentioned problems, the present invention is characterized in that the area of the air jet portion for forming a cylindrical air flow is 20% or less of the total air introduction area. The present invention provides a low-nitrogen-oxide-generating combustor.

Further, in order to solve the above-mentioned problems, according to the present invention, the combustion air introduced into the air pipe has a volume concentration of oxygen of 21.
% Of oxygen-enriched air is used to provide a nitrogen oxide low generation combustion method.

[0019]

[Function] With respect to a diffusion flame formed by jetting fuel from a direction perpendicular to the air stream jetted from the long-hole-shaped air jetting part and separating the fuel from the diffusion flame, a part of the fuel is separated and jetted as an auxiliary fuel. And burning the diffusion flame without fixing it to the air ejection portion or the fuel ejection portion, and before forming the diffusion flame, a part of the combustion gas contains a supplementary fuel flow, an air flow and As it is caught in the fuel flow, it effectively realizes self-exhaust gas recirculation, and at the time of its combustion, the air ejected from the cylindrical air flow forming air ejecting section is tubular air on the downstream side of the shield plate. Flow is formed, and a strong negative pressure portion is formed inside the tubular air flow, further promoting internal recirculation by increasing the reverse flow and recirculation flow of the combustion gas flow in the furnace. With the further promotion of this internal recirculation, a strong ignition source is created by the recirculation of high temperature combustion gas in the furnace, which provides excellent flame holding performance and combustion stability, and the self-exhaust gas recirculation combustion described above is performed. It is intended to effectively promote and significantly reduce NOx.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, in FIGS. 1 and 2, reference numeral 1 is a fuel tube loaded in an air tube 2, and a plurality of long air holes are formed on the outer periphery of the tip of the fuel tube 1. A shield plate 4 provided with a jet portion 3 is installed, a cylindrical air flow forming air jet portion 18 is formed on the edge side of the shield plate 4, and the both sides of the plurality of long hole-shaped air jet portions 3 are A side fuel jet pipe 5 communicating with the fuel pipe 1 is installed, and a side portion of the side fuel jet pipe 5 is
A side fuel jet portion 6 that jets fuel in the circumferential direction is provided. A central axial fuel ejection hole 14 for ejecting auxiliary fuel in the central axial direction of the fuel pipe 1 is provided at the tip of the fuel pipe 1, and the central axial fuel ejection hole 14 is provided.
A disk plate 7 larger than the fuel pipe 1 is provided on the upstream side of the. The shape of the fuel injection hole 14 in the central axis direction may be a slit circular hole 15 as shown in the drawing. The cylindrical air flow forming air ejection portion 18 may be configured by providing an annular slit 19 between the air tube 2 and the shield plate 4 as shown in the drawing, or the shield plate 4 may be provided. It may be configured by arranging the small holes 20 annularly inside the edge.

Air is ejected from the long hole-shaped air ejecting portion 3, and the fuel gas is ejected from the side fuel ejecting portion 6 into the air flow from a direction perpendicular to the air flow. At this time, the ratio of the air flow velocity in the long hole-shaped air jet portion 3 and the fuel gas flow velocity in the side fuel jet portion 6 is set to 0.2 or more, and in actual operation, it is set to about 0.2 to 5. . When the ratio is set to 0.2 or less, the fuel gas penetrates the air flow, collides with the inner wall of the air tube 2 and diffuses to form a flame fixed on the air tube 2, so the ratio is 0. It cannot be less than or equal to 2. However, when the ratio is set as described above, not only does the diffusion flame fixed in the long hole-shaped air ejection portion 3 not occur, but the fuel gas flow 9 ejected from the right angle direction is the air flow as shown in FIG. The flow is in the state of being wrapped in 10. At this time, when the auxiliary fuel is ejected from the central axial fuel ejection hole 14 toward the fuel gas flow 9, the air flow 10, the in-furnace combustion gas flow 11, the internal recirculation region 12, etc.,
Since the auxiliary fuel 17 entrains the combustion gas before it burns, the self-exhaust gas recirculation in the internal recirculation region 12 is further promoted to form the internal recirculation promotion region 8 to further reduce the NOx. realizable. That is, a fuel gas flow 9 is formed in the center, a donut-shaped air flow 10 is formed around it, and a wake indicated by an arrow is formed on the outer periphery thereof. Stream 17 is formed. Thus, the air flow 10 has a high-temperature furnace gas flow 11 from the outside, and at the same time from the inside,
The fuel gas stream 9 and the auxiliary fuel stream 17 are diffusively mixed.
In a normal diffusion flame, a flame is settled in the air ejection hole or the fuel gas ejection hole, so that the fuel starts burning before the air flow accompanies the gas in the surrounding furnace. Has the above-mentioned flow velocity ratio, so that the flame is not attached to the long hole-shaped air ejection portion 3 and the side fuel ejection portion 6. That is, in the present invention, the air flow 10 is the gas flow 1 in the furnace surrounding it.
As the temperature rises while mixing with 1, the fuel gas flow 9 and the auxiliary fuel flow 17 inside thereof gradually form a mixed state. Then, the four members develop a good mixed state, and combustion is started when the ignition conditions are satisfied at various points of temperature, fuel concentration, and oxygen concentration, and a diffusion flame is formed. In such a diffusion flame, a part of the combustion gas is sufficiently mixed with the combustion air, that is, the auxiliary fuel flow before the combustion starts, so that the effect of self-exhaust gas recirculation is maximized and the flame temperature NOx decreases remarkably due to the decrease in the oxygen concentration. In the above, the internal recirculation region 12 and the external recirculation region 13 are defined as the furnace gas flow 11
It greatly contributes to the large amount of wakes.

During the above combustion, the air ejected from the air ejecting portion 18 for forming a cylindrical air flow forms a cylindrical air flow 21 on the downstream side of the shielding plate 4, and the air inside the cylindrical air flow 21 is strongly compressed. Negative pressure part is formed, the back flow of combustion gas in the furnace,
Increased recirculation flow further facilitates self-exhaust gas recirculation within the internal recirculation zone 12. By further promoting this internal recirculation, a strong ignition source is created by the recirculation of high temperature combustion gas in the furnace, resulting in excellent flame holding performance and combustion stability, and the self-exhaust gas recirculation combustion described above is performed. It effectively promotes and promotes the NOx reduction effect (see FIGS. 6 and 7). Even if the cylindrical airflow forming air jetting portion 18 is composed of the annular slit 19 or the small hole 20, the same operational effect is brought about. Further, the area of the above-mentioned cylindrical air flow forming air ejection portion 18 is 2 with respect to the total front air introduction area.
If the area is 0% or less, the above-mentioned effects are promoted.
(See FIG. 7). Further, in the above combustion, the cylindrical air flow forming air ejection portion 18 makes a great contribution to the expansion of the combustion range. That is, FIG. 8 shows the measurement results of the upper limit and the lower limit of the CO limit air ratio with and without the cylindrical air flow forming air jetting portion 18. It can be clearly understood that the cylindrical air flow forming air jetting portion 18 of the present invention has a remarkably large CO upper limit air ratio.

In the case of the present invention in which the side fuel ejection pipes 5 are provided on both sides of the long hole-shaped air ejection portion 3, a plurality of side fuel ejection portions 6 are provided and the shield plate is divided from the plurality of portions. Since the fuel can be jetted in the circumferential direction of 4 and in the direction perpendicular to the air flow 10 of the long hole-shaped air jetting portion 3,
Diffusion mixing with the above-described pre-combustion air stream 10, fuel gas stream 9 and part of the in-furnace combustion gas stream 11 is well performed,
Maintain low NOx combustion more effectively.

Further, since the disc plate 7 is provided, the internal recirculation promoting region 8 is formed on the downstream side of the disc plate 7, the internal recirculation region 12 is expanded, and the recirculation amount of exhaust gas is remarkably increased. However, it further increases the effect of reducing NOx. That is, due to the existence of the disc plate 7, the air flow 1
The expansion of 0 to the high temperature internal recirculation region 12 side is prevented, and the amount of self exhaust gas recirculation increases. Such an increase in the accompanying flow rate remarkably promotes the NOx reduction effect.

Further, by forming the shape of the fuel injection hole 14 in the direction of the central axis into the slit circular hole 15, the ring-shaped fuel is wake-mixed while being expanded, so that the contact area with the in-reactor gas 11 is increased. It increases the amount and further contributes to the NOx reduction effect.

Further, the swirl vane 1 is provided in the slit circular hole 15.
In the case of No. 6, since the fuel is ejected in a ring shape while swirling, the gas entrainment in the furnace is increased, and the wake effect is further improved to promote the NOx reduction effect.

Further, a shield plate 4 provided in contact with the outer periphery of the tip of the fuel tube 1 provided in the air tube 2 and the inner wall of the air tube 2.
Is provided with a long hole-shaped air ejecting portion 3, and the combustion air is ejected from the long hole-shaped air ejecting portion 3, so that the surface area of the jet flow can be increased and the surrounding combustion gas can be efficiently emitted. Can be waked. In addition, the long hole-shaped air ejection portion 3
Is formed in plural, the air flow 10 is divided and ejected, and each jet is accompanied by the in-furnace gas flow 11. Therefore, compared with a combustor having a single air jet, The surrounding combustion gas can be efficiently circulated, and the effect of self-exhaust gas recirculation can be enhanced. An internal recirculation region 12 is formed in a portion surrounded by a plurality of combustion air jets, and an external recirculation region 13 is formed in the periphery, so that a part of the combustion gas is recirculated in both recirculation regions. And is accompanied by the jet of combustion air. In particular, since the high temperature combustion gas circulates in the internal recirculation region 12, a diffusion flame having no fixing portion is ignited stably to form a flame.

By jetting the fuel at right angles to the air flow and adjusting the ratio of the air flow velocity to the fuel flow velocity as described above, the fuel jet can be jetted to the center of the combustion air jet. . In this case, as shown in FIGS. 4 and 5, the fuel jet forms a so-called twin vortex. As the fuel and the air are mixed, the vortices develop as they move away from the side fuel jet portion 6 and further from the long hole-shaped air jet portion 3. Not only the fuel and air are mixed in this vortex, but also a part of the combustion gas entrained in the air is gradually entrained, and a sufficient amount of combustion gas for fuel ignition is entrained. Then, the fuel starts to burn. Due to this vortex, the flame is stably ignited without being fixed to the long hole-shaped air ejection portion 3 and further to the side fuel ejection portion 6. When the fuel is jetted in a direction perpendicular to the direction of the air flow 10 passing through the long hole-shaped air jet portion 3, if the ratio of the flow velocity of the combustion air jet to the fuel jet is set to 0.2 or more, the flame As described above, is formed without fixing to the ejection holes, resulting in a significantly low NOx flame.

During the above combustion, the auxiliary fuel is ejected from the fuel injection hole 14 in the central axis direction of the fuel pipe 1, so that the auxiliary fuel and the gas in the furnace are mixed before combustion as described above. The NOx reduction effect is further promoted by synergistically promoting the above-mentioned combustion. During such self-exhaust gas recirculation combustion, the cylindrical air flow 21 formed by the above-mentioned cylindrical air flow forming air jetting portion 18 forms an effective continuous ignition source therein, and the self-exhaust gas recirculation combustion is effective. It is as described above that it is to be stabilized.

In the above combustion, when the shape of the fuel injection hole 14 in the central axis direction is formed as the slit circular hole 15,
Since the auxiliary fuel is jetted in a ring shape, the contact area with the gas in the furnace is increased and the wake effect is remarkably improved, so that N
Promotes Ox reduction effect.

Further, the swirl vane 1 is provided in the slit circular hole 15.
In the case of No. 6, since the fuel is ejected in a ring shape while swirling, the gas entrainment in the furnace is increased, and the wake effect is further improved to promote the NOx reduction effect.

By using oxygen-enriched air having a volume concentration of oxygen of 21% or more as the combustion air to be introduced into the air pipe 2 in the above combustion, low NOx combustion can be continued and the combustion amount can be increased. Can be increased.

FIG. 6 shows the NOx reduction effect according to the present invention. According to FIG. 6 comparing with the conventional example, air /
Fuel flow velocity ratio is 0.2 or more and 10-20 of all fuels
% As auxiliary fuel, and if the area of the cylindrical air flow forming air ejection portion 18 is 20% or less of the total air introduction portion area, NOx is significantly reduced over a wide practical air ratio. Can understand.

[0034]

The present invention solves the conventional problems all at once by using the low NOx combustion method and its apparatus as described above, and as shown in FIG. 7, a cylindrical air flow forming air ejecting portion. By configuring the area of 20% or less of the total air introduction portion area, the generation of NOx can be remarkably suppressed as compared with the conventional burner. that time,
The internal circulation flow formed inside the cylindrical air flow serves as a strong continuous ignition source for the flame and stably promotes the self-exhaust gas recirculation combustion. In addition, FIG.
The results of measuring the upper and lower limits of the CO limit air ratio in the case where there is an air jet for forming a cylindrical air flow and in the case where it is not provided are shown in FIG. It can be understood that the forming air jetting portion has the effect of significantly increasing the CO upper limit air ratio.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

FIG. 3 is a schematic diagram showing a fluid flow and a wake state.

FIG. 4 is a schematic diagram showing a fuel flow in an air flow.

FIG. 5 is a schematic diagram showing a fuel flow in an air flow.

FIG. 6 is a NOx performance diagram comparing the present invention with a conventional method.

FIG. 7 is a NOx performance chart comparing the effect of the ratio of the area of the air ejecting portion for forming a cylindrical air flow of the present invention with respect to the total air introduction area, compared with a conventional burner.

FIG. 8 is a performance comparison diagram showing the results of measurement of the upper limit and the lower limit of the CO limit air ratio with and without the cylindrical air flow forming air ejection portion.

[Explanation of symbols] [Explanation of symbols]

 1 Fuel Pipe 2 Air Pipe 3 Long Hole Air Jet 4 Shield 5 Side Fuel Jet 6 Side Fuel Jet 7 Disc Plate 8 Internal Recirculation Promotion Area 9 Fuel Gas Flow 10 Air Flow 11 Reactor Gas Flow 12 Internal recirculation area 13 External recirculation area 14 Central axial fuel injection hole 15 Slit circular hole 16 Swirl vane 17 Auxiliary fuel flow 18 Cylindrical air flow forming air injection part 19 Annular slit 20 Small hole 21 Cylindrical air flow

Claims (13)

[Claims] 1. A shield plate provided with a plurality of elongated hole-like air jets is installed on the outer periphery of the tip end of a fuel pipe charged in an air pipe, and a cylindrical air flow forming air jet is provided on the edge side of the shield plate. And a side fuel ejection pipe communicating with the fuel pipe is installed on both sides of the plurality of long hole-shaped air ejection portions, and the side surface of the fuel ejection pipe has a circumferential direction of the shield plate. A side fuel jetting portion for jetting fuel is provided, the tip end portion of the fuel pipe is projected from the shield plate, and the auxiliary fuel is jetted to the tip end portion of the fuel pipe in the central axis direction of the fuel pipe. A fuel ejection hole is provided, a disk plate larger than the fuel pipe is installed upstream of the fuel ejection hole in the central axis direction, and the elongated hole is formed while ejecting air from the cylindrical airflow forming air ejection portion. The air flow ejected from the air jets from both sides of the side fuel jets. While the fuel is jetted at right angles to cause mixed combustion, 10% to 20% of the total fuel is jetted in the central axis direction as auxiliary fuel from the central axial fuel jet holes,
It is characterized in that combustion energy is burnt in the furnace by the jetting energy while being accompanied, and the ratio of the air flow velocity at the elongated hole air jetting portion to the fuel flow velocity at the side fuel jetting portion is 0.2 or more. A method for low-nitrogen oxide combustion. 2. A shield plate provided with a plurality of elongated hole-like air jetting portions is provided on the outer periphery of the tip end of the fuel pipe charged in the air pipe, and a cylindrical air flow forming air jet is provided on the edge side of the shield plate. And a side fuel ejection pipe communicating with the fuel pipe is installed on both sides of the plurality of long hole-shaped air ejection portions, and the side surface of the fuel ejection pipe has a circumferential direction of the shield plate. A side fuel jetting portion for jetting fuel is provided, the tip end portion of the fuel pipe is projected from the shield plate, and the auxiliary fuel is jetted to the tip end portion of the fuel pipe in the central axis direction of the fuel pipe. A low-nitrogen oxide generation combustion apparatus, characterized in that a fuel injection hole is provided, and a disk plate larger than the fuel tube is installed upstream of the fuel injection hole in the central axis direction. 3. The shape of the central axial fuel injection hole is formed as a slit circular hole, and a ring-shaped fuel is ejected from the central axial fuel injection hole, and burns while wake mixing the in-reactor gas. The method for low-nitrogen oxide generation combustion according to claim 1, wherein the method is as described above. 4. The low-nitrogen oxide combustion device according to claim 2, wherein the shape of the fuel injection hole in the central axis direction is a slit circular hole. 5. A swirl vane is provided in the slit circular hole, and a swirling ring-shaped fuel is ejected from the slit circular hole to carry out mixed combustion with the gas in the furnace accompanied. 4. A method for low-nitrogen oxide combustion according to 1. 6. The low-nitrogen oxide combustion apparatus according to claim 4, wherein a swirl vane is provided in the slit circular hole. 7. The cylindrical air flow forming air jetting portion is configured by providing an annular slit between the air tube and the shield plate,
6. The low-nitrogen-oxide generation combustion method according to claim 1, wherein combustion is performed while ejecting air in a cylindrical shape from the annular slit. 8. The cylindrical air flow forming air jetting portion is configured by providing an annular slit between the air tube and the shield plate, as set forth in claim 2, 4, or 6. Nitrogen oxide low generation combustor. 9. The cylindrical air flow forming air jetting portion is constituted by arranging a large number of small holes annularly inside the edge of a shield plate, and air is jetted and burned from the large number of small holes. 6. The low-nitrogen-oxide generation combustion method according to claim 1, 3 or 5, wherein. 10. The cylindrical air flow forming air jetting portion is constituted by arranging a large number of small holes annularly inside the edge of the shield plate. 6. A low-nitrogen oxide combustion device according to item 6. 11. The cylindrical air flow forming air jetting portion is configured to have an area of 20% or less with respect to the total air introduction area for combustion. 7
And a method for low-nitrogen oxide combustion according to item 9 above. 12. The area of the air ejecting portion for forming a cylindrical air flow is set to be 20% or less of the total air introduction area, as claimed in claim 2, 4, 6, 8 and 10
A low-nitrogen oxide generation combustion device as described. 13. The oxygen-enriched air having a volume concentration of oxygen of 21% or more is used as the combustion air to be introduced into the air pipe, according to any one of claims 1, 3, 5, 7, 9 and 11. Method of low-nitrogen oxide generation combustion of.