KR102509551B1 - Low NOx Burner - Google Patents

Abstract

The present invention relates to an industrial low NOx burner capable of equalizing a combustion reaction area and temperature distribution in a combustion furnace and remarkably reducing a generation amount of NOx by enabling flameless combustion in which a boundary of flame disappears so that the flame is invisible to a naked eye. According to the present invention, the industrial low NOx burner includes: a barrel-shaped burner housing having an open front surface and an air inlet which air for combustion flows in, wherein the burner housing is connected to one end of the combustion furnace; a diffuser connected to a front end of the burner housing and spraying the air for combustion supplied into the burner housing while diffusing the air for combustion into the combustion furnace in the front; a first fuel nozzle installed for a front end to be inserted into a nozzle accommodation hole of the diffuser through the center of the burner housing, wherein the first fuel nozzle firstly sprays fuel gas into a diffusion space until the temperature in the combustion furnace reaches a predetermined temperature; and multiple second fuel nozzles installed to penetrate a position separated at a fixed distance in a radial direction from the center of the diffuser through a periphery unit of the burner housing, and spraying the fuel gas into the combustion furnace when the first fuel nozzle completes the spray of the fuel gas.

Description

Industrial Low NOx Burner {Low NOx Burner}

The present invention relates to an industrial burner, and more particularly, to configure a diffuser having a multi-stage diffusion space at the end of a fuel nozzle to spread and evenly distribute combustion air, and to a primary fuel nozzle disposed in the center of the diffuser and to the peripheral area. By sequentially supplying and burning fuel gas according to the temperature in the combustion furnace through a plurality of secondary fuel nozzles arranged, the temperature distribution and combustion reaction area in the combustion furnace become uniform and the boundary of the flame disappears, making the flame invisible to the naked eye. It relates to an industrial low NOx burner capable of reducing the amount of NOx generated by enabling flameless combustion.

In general, nitrogen oxides mean NO and NO ₂ and are usually expressed as NOx (nox), which is generated in large quantities when fossil fuels are burned.

The generation of rust is affected by flame temperature, oxygen concentration and nitrogen content in fuel, but these can be changed by changing operating conditions and combustion methods to reduce rust.

NOx is fuel rust (NOx in fuel), which is produced by oxidation of components that are chemically bound to fuel during combustion, and thermal rust, which is produced by oxidizing nitrogen molecules in the combustion air when nitrogen in the combustion air is oxidized at high temperatures. (NOx at temperature), and Prompt NOx furnace, which is rapidly generated when hydrocarbon-based fossil fuel is oxidized at high temperature in a high-concentration state to generate nitrogen molecules in the combustion air, or when hydrocarbon-based fossil fuel is exposed to a high-temperature region in a high-concentration state. can be distinguished.

Among the rusts, fuel rust, which is rust in fuel, cannot be controlled by combustion technology, so the industry is concentrating on developing burners that can control thermal rust and prompt rust.

NOX is produced by the reaction of oxygen and nitrogen in the air. Oxygen and nitrogen have very low mutual reactivity at room temperature, but react with each other at high temperature (1500 ℃ or higher) to generate NO.

Therefore, since the flame surface area, which is the highest temperature area in most furnaces, usually reaches a temperature of 1200 to 1750 ° C, this reaction (N ₂ + O ₂ = 2NO) becomes an important source of NO production.

When NO is produced in this way, the decomposition reaction rate is slow, so it does not decompose again into N ₂ and O ₂ , but reacts with oxygen again to produce NO ₂ (2NO + O ₂ = 2NO ₂ ).

This reaction is a reaction in which the rate of reaction slows down as the temperature increases.

Therefore, NO production is active at high temperatures, and when the temperature of the gas gradually decreases, the high-temperature NO is decomposed into N ₂ and O ₂ .

Therefore, in order to reduce the generation of rust, it is desirable to more uniformly supply combustion air throughout the furnace and at the same time lower the flame temperature of the burner as much as possible.

To this end, Korean Patent Registration No. 10-0784880 (Low NOx burner) is capable of simultaneously reducing the generation of Thermal NOx and Prompt NOx by implementing high-speed flame generation, rapid mixing of fuel and air, and self-recirculation of combustion gas. Korean Patent Registration No. 10-0855719 discloses that rust can be reduced by adjusting the diameter of the fuel diffusion part by installing a fuel diffusion part that is detachable at the tip of the fuel supply pipe and has a larger diameter than the diameter of the fuel supply pipe. made it possible

However, the low NOx type burner of the above registered patents has a problem in that the device is complicated and troublesome.

In addition, Korean Patent Registration No. 10-1022722 (low NOx burner) discloses an air supply pipe supplying air into a combustion furnace and having an inclined cross section formed at the tip thereof, a fuel supply pipe installed inside the air supply pipe and supplying fuel, the A head located on the outer circumferential surface of the front end of the fuel supply pipe, a plurality of fuel nozzles installed on the outer circumferential surface of the head, and a low NOx burner having an air supply passage for supplying air into the combustion furnace between the inclined end surface of the air supply pipe and the head, wherein the An air control pipe is installed between the air supply pipe and the fuel supply pipe so that the air supply amount can be adjusted by adjusting the width of the air supply passage.

This registered patent can adjust the amount of combustion air supplied into the combustion furnace by adjusting the width of the air supply passage, but there is a problem in that the air is not evenly distributed in the air supply pipe and thus the combustion air is not evenly supplied to the positions of each head. .

In addition, in the conventional low-NOx burner, fuel gas is injected from the central injection port and combusted through a process of mixing with combustion air, so that a high combustion temperature is maintained as a large amount of energy is released in a relatively narrow area, and thus the amount of rust is relatively increased. do.

Republic of Korea Patent No. 10-0784880 Republic of Korea Patent No. 10-0855719 Republic of Korea Patent Registration No. 10-1022722

The present invention is to solve the above problems, and an object of the present invention is to uniformly distribute the air supplied into the combustion furnace, to make the temperature distribution and combustion reaction area in the furnace uniform, and to disappear the boundary of the flame to visually see. An object of the present invention is to provide an industrial low NOx burner capable of significantly reducing the amount of NOx generated by enabling flameless combustion in which the flame is not visible.

Industrial low NOx burner according to the present invention for achieving the above object, the front surface is formed to be open, the air inlet into which air for combustion is introduced is formed is coupled to one end of the combustion furnace burner housing in the form of a cylinder; a diffuser that is coupled to the front end of the burner housing and spreads and injects combustion air supplied into the burner housing into a front combustion furnace; The first fuel is installed so that the front end is inserted into the nozzle receiving hole of the diffuser through the center of the burner housing to primarily inject fuel gas into the diffusion space until the temperature in the furnace reaches a predetermined temperature. Nozzle; and a plurality of nozzles installed so as to pass through a periphery of the burner housing at a location spaced apart from the center of the diffuser by a predetermined distance in a radial direction, and injecting fuel gas into the combustion furnace when the fuel gas injection of the first fuel nozzle is finished. A second fuel nozzle; may be included.

An industrial low-NOx burner according to a preferred embodiment of the present invention includes a cylindrical burner housing having an open front surface and having an air inlet into which air for combustion is introduced and coupled to one end of a combustion furnace; It is coupled to the front end of the burner housing, a nozzle receiving hole is formed at the rear of the center, and has a larger diameter than the nozzle receiving hole in front of the nozzle receiving hole, and the rear surface communicates with the nozzle receiving hole and the front surface communicates into the combustion furnace. A diffusion space is formed, and a plurality of inner air supply holes penetrating from the rear end of the nozzle receiving hole to the rear end of the multi-stage diffusion space are arranged at regular intervals along the circumferential direction at the radially outer side of the diffusion space. a diffuser in which a plurality of external air supply holes communicating with the inside of the burner housing and the combustion passage are formed to penetrate in the forward and backward directions; The first fuel is installed so that the front end is inserted into the nozzle receiving hole of the diffuser through the center of the burner housing to primarily inject fuel gas into the diffusion space until the temperature in the furnace reaches a predetermined temperature. Nozzle; and a plurality of nozzles installed so as to pass through a periphery of the burner housing at a location spaced apart from the center of the diffuser by a predetermined distance in a radial direction, and injecting fuel gas into the combustion furnace when the fuel gas injection of the first fuel nozzle is finished. A second fuel nozzle; may be included.

The second fuel nozzle may be installed at a position further away from the outer air supply hole of the diffuser in a radial direction.

The inner diameter of the second fuel nozzle is preferably smaller than the inner diameter of the first fuel nozzle.

Arranged at regular intervals along the circumferential direction on the outer circumferential surface of the front end of the first fuel nozzle inserted into the nozzle accommodating hole, extending spirally along the front-back direction or twisted at a certain angle with respect to the axial direction, the inner circumferential surface of the nozzle accommodating hole and a plurality of swirl blades for swirling combustion air flowing between the outer circumferential surface of the front end of the first fuel nozzle.

The swirl blade may be integrally formed on an outer surface of a ring-shaped blade head detachably coupled to an outer circumferential surface of an end of the first fuel nozzle.

The inner air supply hole and the outer air supply hole may obliquely extend radially inward from the rear toward the front.

The diffusion space of the diffuser may form a multi-stage diffusion space when a plurality of diffusion spaces having a larger inner diameter are continuously arranged toward the front.

The individual diffusion spaces constituting the multi-stage diffusion space of the diffuser may be formed in a cone shape with an inner diameter gradually increasing from the rear to the front.

According to the present invention, the fuel gas is injected through the first fuel nozzle in the center to primarily generate a flame, and the fuel gas is injected through a plurality of second fuel nozzles in the periphery above a certain temperature, so that the combustion area is widely distributed. As the combustion rate decreases, the combustion temperature can be lowered, and the concentration of rust proportional to the combustion temperature can be reduced.

In addition, since combustion air can be uniformly diffused through the multi-stage diffusion space formed at the center of the diffuser and reacted with the fuel gas to generate a flame, the amount of rust generation can be further reduced.

1 is a perspective view of an industrial low NOx burner according to an embodiment of the present invention.
2 is a longitudinal cross-sectional view of an industrial low NOx burner according to an embodiment of the present invention.
3 is a cross-sectional view of an industrial low NOx burner according to an embodiment of the present invention.
4 is a front view of a diffuser constituting an industrial low NOx burner according to an embodiment of the present invention.
5 is a longitudinal cross-sectional view showing a modified example of an industrial low NOx burner according to an embodiment of the present invention.
6 is a view showing the principle of flameless operation of an industrial low NOx burner according to an embodiment of the present invention.
7 is a diagram showing a comparison of flame temperature changes of a flameless low NOx burner and a general flame generating low NOx burner according to the present invention.
Figure 8a is a graph showing the amount of rust (NOx) generation according to the temperature change in the combustion furnace of a general flame-generating low NOx burner.
Figure 8b is a graph showing the amount of NOx generated according to the temperature change in the combustion furnace of the flameless low NOx burner according to the present invention.
9 is a cross-sectional view showing another embodiment of a diffuser constituting an industrial low NOx burner according to the present invention.

An industrial low NOx burner according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. Since the present invention can have various changes and various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

In addition, unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

1 to 4, the industrial low NOx burner 100 according to an embodiment of the present invention includes a cylindrical burner housing 110 coupled to one end of the combustion furnace 10, the burner housing ( 110) coupled to the front end of the diffuser 120, the first fuel nozzle 130 coupled to the center of the rear portion of the diffuser 120 through the center of the burner housing 110, and the periphery of the burner housing 110 A plurality of second fuel nozzles 140 coupled to the periphery of the diffuser 120 and a swirl member 150 coupled to the outer circumferential surface of the front end of the first fuel nozzle 130 to swirl combustion air through include

The burner housing 110 has a cylindrical shape with an open front end and is attached to the outside of the rear end of the combustion furnace 10 . At one side of the burner housing 110, an air inlet 112 through which combustion air is introduced into the internal space is formed to be open. The air inlet 112 is connected to an air supply device (not shown) to supply room temperature or preheated air for combustion to the internal space of the burner housing 110 .

At the rear end of the burner housing 110, a fuel supply unit 160 is installed that is connected to the rear ends of the first fuel nozzle 130 and the second fuel nozzle 140 to supply fuel gas. The fuel gas may be landfill gas (LFG, land fill gas) or a mixed gas in which LFG and biogas are mixed. In addition, as a fuel gas, LNG or a mixed gas obtained by mixing LNG and biogas may be used. The fuel supply unit 160 is connected to a fuel gas supply source to receive fuel gas, and the fuel gas is supplied to the first fuel nozzle 130 and the second fuel nozzle 140 as the flow path is switched by a control unit (not shown) of the combustion system. A flow control valve 161 supplying one of the first fuel supply pipe 162 and the second fuel supply pipe 162 connecting the flow control valve 161 to the first fuel nozzle 130 and the second fuel nozzle 140, respectively. A fuel supply pipe 163 may be included.

The diffuser 120 forms a flame ignition area in the front center so that fuel gas and combustion air react to facilitate the formation of flame, and has a function of guiding the flame generated as the fuel gas and combustion air are combusted forward. do.

The diffuser 120 may be made of high-temperature refractory cement. A nozzle accommodating hole 121 into which the front end of the first fuel nozzle 130 is inserted is formed at the rear of the center of the diffuser 120, and a plurality of diffusers having larger inner diameters are formed in front of the nozzle accommodating hole 121. A multi-stage diffusion space 122 in which spaces 122a and 122b are continuously arranged is formed to open forward. In addition, a plurality of inner air supply holes 123 penetrating from the rear end of the nozzle accommodating hole 121 to the rear end of the multi-stage diffusion space 122 may be arranged at regular intervals along the circumferential direction. Further, a plurality of external air supply holes 124 communicating with the inside of the burner housing 110 and the combustion furnace 10 are formed radially outside the multi-stage diffusion space 122 to pass through in the forward and backward directions.

Therefore, part of the air introduced into the burner housing 110 through the air inlet 112 of the burner housing 110 is transferred to the space between the inner circumferential surface of the nozzle receiving hole 121 and the outer circumferential surface of the first fuel nozzle 130 and the above The air is supplied to the inside of the multi-stage diffusion space 122 through the inner air supply hole 123, and the remaining part of the air is supplied into the combustion furnace 10 through the outer air supply hole 124.

The individual diffusion spaces 122a and 122b constituting the multi-stage diffusion space 122 of the diffuser 120 may each have a constant diameter, but as shown in FIGS. 2 and 3, each individual diffusion space ( 122a, 122b) may have a cone shape with an inner diameter gradually increasing from the rear to the front.

As described above, when the multi-stage diffusion space 122 of the diffuser 120 has a cone shape, combustion air supplied to the inside of the multi-stage diffusion space 122 through the swirl member 150 and the inner air supply hole 123 Uniform diffusion can be achieved by flowing forward while turning smoothly.

In addition, the inner air supply hole 123 and the outer air supply hole 124 may extend parallel to the axial direction, but as shown in FIG. 5, the inner air supply hole 123 and the outer air supply hole 124 are It may have a structure that obliquely extends radially inward from the rear toward the front.

In addition, the diffuser 120 has a plurality of holes 125 for accommodating an ignition device 171 such as a pilot burner installed through the burner housing 110 and a flame detection device 172 such as an ultraviolet detector in a multi-stage diffusion space. (122) and may be formed in communication.

The first fuel nozzle 130 is made of metal having excellent heat resistance, and is installed so that the front end is inserted into the nozzle receiving hole 121 of the diffuser 120 through the center of the rear surface of the burner housing 110 . The first fuel nozzle 130 generates a flame by primarily injecting fuel gas into the multi-stage diffusion space 122 of the diffuser 120 until the temperature in the furnace 10 reaches a predetermined temperature. .

The outer diameter of the front end of the first fuel nozzle 130 is smaller than the inner diameter of the nozzle receiving hole 121 so that combustion air flows between the outer circumferential surface of the front end of the first fuel nozzle 130 and the inner circumferential surface of the nozzle receiving hole 121. space is created.

As the combustion air flowing through the space between the inner circumferential surface of the nozzle accommodating hole 121 and the outer circumferential surface of the front end of the first fuel nozzle 130 is introduced into the multi-stage diffusion space 122, the fuel gas and combustion air are further supplied. In order to ensure uniform mixing, a swirl member 150 is installed between the inner circumferential surface of the nozzle receiving hole 121 and the outer circumferential surface of the front end of the first fuel nozzle 130 .

The swirl member 150 includes a ring-shaped blade head 151 detachably coupled to the outer circumferential surface of the front end of the first fuel nozzle 130, and a plurality of swirls integrally formed on the outer surface of the blade head 151. A blade 152 may be included. The swirl blade 152 spirally extends along the front-back direction or is formed to be twisted at a certain angle with respect to the axial direction, and the combustion flows between the inner circumferential surface of the nozzle receiving hole 121 and the outer circumferential surface of the front end of the first fuel nozzle 130. It functions to spread the air uniformly while turning it.

At this time, in order to stabilize the air flow by generating a Coanda effect in which combustion air guided along the swirl blade 152 flows along the surface of the swirl blade 152, the swirl blade 152 has a rear portion It may have a convex airfoil shape. That is, each of the plurality of swirl blades 152 may have an airfoil shape in which a leading edge is formed at the rear end and a trailing edge is formed at the front end.

When the swirl blade 152 is formed on the ring-shaped blade head 151 that can be attached to and detached from the outer circumferential surface of the first fuel nozzle 130, the first fuel nozzle 130 itself is not processed, and a separate swirl member ( 150), the swirl member 150 can be attached and detached from the first fuel nozzle 130 as needed, so it is very easy to manufacture and use.

The second fuel nozzle 140 is installed to penetrate the periphery of the diffuser 120 through the periphery of the burner housing 110, that is, a position spaced apart from the center of the diffuser 120 by a predetermined distance in the radial direction, so that the first fuel nozzle When the supply of the fuel gas in 130 is finished, the fuel gas is injected into the combustion furnace 10 . The second fuel nozzle 140 is preferably disposed further away from the outer air supply hole 124 of the diffuser 120 in the radial direction. In addition, the second fuel nozzle 140 preferably has a diameter smaller than that of the first fuel nozzle 130 so that the fuel gas jet can be injected into the furnace 10 .

In this embodiment, two second fuel nozzles 140 are installed close to both side edges of the diffuser 120, so that the oxygen concentration in the furnace 10 is low (approximately 3% or less) and the concentration of the incombustible diluent is high. By injecting fuel gas directly into the combustion gas recirculation zone as a high-speed jet, flameless operation is possible. Flameless operation is an operation state in which the temperature distribution and combustion reaction area in the combustion furnace 10 become uniform and the flame boundary disappears, making the flame invisible to the naked eye. Phosphorus flames are not visible.

Referring to FIG. 6, since the fuel gas injected as a high-speed jet by the second fuel nozzles 140 on both sides is mixed with combustion air and recirculation combustion gas at a temperature lower than the ignition point of the fuel gas, the fuel gas and combustion air forms a reaction zone and is sufficiently mixed before flame is generated. The fuel gas injected from the second fuel nozzle 140 consumes oxygen in the combustion furnace 10 while reacting with oxygen (concentration less than 3%) of the recirculating combustion gas.

Under these flameless operating conditions, NOx (Nox) production is significantly reduced (see the graphs of FIGS. 7 and 8A and 8B), which is due to the mixture of reactants and non-combustible diluents, resulting in a small flame, low combustion temperature, and a high combustion area. because it expands In addition, since the fuel gas is not concentrated in the center but dispersed in multiple locations around the periphery, there is no flame front, which is a major area for NOx formation, and the reaction rate of nitrogen can be relatively reduced by lowering the concentration of oxygen in the flame.

The low NOx burner with this configuration operates as follows.

Combustion air introduced through the air inlet 112 of the burner housing 110 is transferred to the space between the inner circumferential surface of the nozzle receiving hole 121 at the center of the diffuser 120 and the outer circumferential surface of the first fuel nozzle 130 and the inner air supply hole ( 123) is supplied to the inside of the multi-stage diffusion space 122. At this time, the combustion air introduced into the space between the inner circumferential surface of the nozzle receiving hole 121 and the outer circumferential surface of the first fuel nozzle 130 turns while passing through the swirl blade 152, and a swirling flow is generated inside the multi-stage diffusion space 122. Thus, it can be uniformly mixed with the fuel gas supplied through the first fuel nozzle 130. In addition, the multi-stage diffusion space 122 has a larger diameter when the individual diffusion spaces 122a and 122b are disposed in the front, so that the combustion air flows forward and diffuses more smoothly, so that the mixture with the fuel gas is uniform. As this is done, flames may be generated, which has a beneficial effect on reducing rust.

At this time, a flame is generated while a predetermined amount of combustion air is injected through the external air supply hole 124 of the diffuser 120 .

As fuel gas is supplied through the first fuel nozzle 130 and air for combustion is supplied through the diffuser 120, a flame is generated. (For example, 500 ~ 700 ℃), the control unit switches the flow control valve 161 of the fuel supply unit 160 to cut off the supply of fuel gas to the first fuel nozzle 130, and a plurality of second fuel A flow path is controlled to supply fuel gas to the nozzle 140 . The temperature at which the fuel gas is supplied through the second fuel nozzle 140 is slightly lower than the ignition temperature of the fuel gas, which is a combustion furnace before the fuel gas creates a flame, that is, before the fuel gas and combustion air react. This is to sufficiently mix oxygen (O ₂ ) in the combustion gas inside, air for combustion, and fuel gas.

The fuel gas supplied through the plurality of second fuel nozzles 140 is injected into the combustion gas recirculation zone in the periphery of the combustion furnace 10, so that flameless operation is performed. At this time, in the course of combustion of the fuel gas injected through the second fuel nozzle 140, residual oxygen in the combustion gas circulating around the combustion furnace 10 reacts and consumes oxygen, so flameless combustion can proceed. there is. The amount of rust generated can be remarkably reduced by the flameless operation as described above.

As described above, in the low NOx burner of the present invention, fuel gas is injected through the first fuel nozzle 130 in the center to primarily generate a flame, and a plurality of second fuel nozzles 140 in the periphery above a certain temperature Through the fuel gas is injected, the combustion area is widely distributed, and the combustion speed is reduced, thereby lowering the combustion temperature and reducing the concentration of NOx in proportion to the combustion temperature.

In addition, since combustion air can be uniformly diffused through the multi-stage diffusion space 122 formed in the center of the diffuser 120 and reacted with the fuel gas to generate flame, the amount of rust can be further reduced.

9 shows a diffuser 120 of an industrial low NOx burner according to another embodiment of the present invention, and the industrial low NOx burner of this embodiment has a cylindrical shape attached to the inner circumferential surface of the multi-stage diffusion space 122 of the diffuser 120. It further includes a mesh member 180 made of a mesh.

The mesh member 180 is made of a cylindrical mesh made of a heat-resistant metal material, and additionally generates a vortex in the swirling flow of the combustion air flowing into the multi-stage diffusion space 122 to further increase the combustion air. In addition to enabling uniform mixing, it acts to further reduce the occurrence of rust by absorbing thermal energy.

The mesh member 180 may have a mesh structure in which hollow tubes are woven horizontally and vertically, and may be configured to absorb heat energy more effectively by filling the hollow tube with a phase change material that absorbs heat and changes phase.

Although the detailed description of the present invention described above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those having ordinary knowledge in the art will find the spirit of the present invention described in the claims to be described later. And it will be understood that the present invention can be variously modified and changed without departing from the technical scope.

10: combustion furnace 100: low NOx burner
110: burner housing 112: air inlet
120: diffuser 121: nozzle receiving hole
122: multi-stage diffusion space 123: inner air supply hole
124: external air supply hole 130: first fuel nozzle
140: second fuel nozzle 150: swirl member
160: fuel supply unit 171: ignition device
172: flame detection device 180: mesh member

Claims (9)

a cylindrical burner housing having an open front surface, an air inlet through which air for combustion is introduced, and coupled to one end of the combustion furnace;
It is coupled to the front end of the burner housing, a nozzle receiving hole is formed at the rear of the center, and has a larger diameter than the nozzle receiving hole in front of the nozzle receiving hole, and the rear surface communicates with the nozzle receiving hole and the front surface communicates into the combustion furnace. A diffusion space is formed, and a plurality of inner air supply holes penetrating from the rear end of the nozzle receiving hole to the rear end of the diffusion space are arranged at regular intervals along the circumferential direction, radially outside of the diffusion space. a diffuser in which a plurality of external air supply holes communicating with the inside of the burner housing and the combustion passage are formed to pass through;
The front end is installed to be inserted into the nozzle receiving hole of the diffuser through the center of the burner housing, and the fuel gas is primarily injected into the diffusion space in the axial direction until the temperature in the furnace reaches a predetermined temperature a first fuel nozzle; and,
It is installed to penetrate a position spaced apart from the center of the diffuser by a predetermined distance in the radial direction through the periphery of the burner housing, and injects fuel gas axially into the combustion furnace when the fuel gas injection of the first fuel nozzle is finished. of the second fuel nozzle; and,
a fuel supply unit connected to the rear ends of the first fuel nozzle and the second fuel nozzle to supply fuel gas to the rear end of the burner housing;
including,
The fuel supply unit is connected to a fuel gas supply source to receive fuel gas, and a flow control valve for supplying fuel gas to one of the first fuel nozzle and the second fuel nozzle while the flow path is switched by the control unit, and the flow control valve Including a first fuel supply pipe and a second fuel supply pipe respectively connected to the first fuel nozzle and the second fuel nozzle,
The diffusion space of the diffuser is an industrial low NOx burner in which a plurality of diffusion spaces having a larger inner diameter are continuously arranged to form a multi-stage diffusion space toward the front. The industrial low NOx burner of claim 1, wherein the second fuel nozzle is installed at a position further away from the outer air supply hole of the diffuser in a radial direction. The low NOx industrial burner according to claim 1 or 2, wherein an inner diameter of the second fuel nozzle is smaller than an inner diameter of the first fuel nozzle. The method of claim 1, wherein the first fuel nozzle is arranged at regular intervals along the circumferential direction on the outer circumferential surface of the front end of the first fuel nozzle inserted into the nozzle receiving hole, and is spirally extended along the front-back direction or twisted at a certain angle with respect to the axial direction. a plurality of swirl blades formed to swirl combustion air flowing between the inner circumferential surface of the nozzle receiving hole and the outer circumferential surface of the front end of the first fuel nozzle;
An industrial low-NOx burner further comprising a. The industrial low NOx burner of claim 4, wherein the swirl blade is integrally formed on an outer surface of a ring-shaped blade head detachably coupled to an outer circumferential surface of an end of the first fuel nozzle. The industrial low NOx burner according to claim 1, wherein the inner air supply hole and the outer air supply hole obliquely extend radially inward from the rear toward the front. delete The industrial low NOx burner according to claim 1, wherein the individual diffusion spaces constituting the multi-stage diffusion space of the diffuser have a cone shape with inner diameters gradually increasing from the rear to the front. The industrial low NOx burner according to claim 1, wherein a cylindrical mesh member made of a heat-resistant material is installed on the inner circumferential surface of the diffusion space of the diffuser.

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