JP2019509451A - Combined low NOx burner - Google Patents

Abstract

The present invention relates to a combined low-NOx burner that reduces the amount of NOx generated by implementing a gas staging combustion technique and an IFGR (Internal Free Gas Recycling) combustion technique in one burner. A composite low NOx burner according to the present invention is a composite low NOx burner installed in a burner mounting hole of a combustion chamber, and is inserted into the burner mounting hole so that a tip is exposed to the combustion chamber and air is supplied to the combustion chamber. A tube to be guided and provided at least one at an end portion of the tube, and has a pipe shape for injecting fuel into the combustion chamber to form a divided flame. A fuel spud in which a gas inlet is formed, and a second gas inlet for inflow of combustion gas mixed with air inside the tube from the first gas inlet to the rear of the combustion chamber in the outer direction Is formed on the outer periphery of the tube. According to the present invention, by combining the gas staging technology with the improved IFGR technology burner that effectively performs the self-recirculation of the combustion gas, the present invention is more effective than the low NOx burner to which the existing IFGR technology is applied. Has the effect of further reducing the amount of NOx generated.

Description

  The present invention relates to a low NOx burner, and more specifically, the amount of NOx generated by implementing a gas staging combustion technique and an IFGR (Internal Fluid Gas Recycling) combustion technique in one burner. The present invention relates to a composite-type low NOx burner that reduces the above.

Generally, nitrogen oxide (NOx) is fuel NOx produced by oxidation of a nitrogen component chemically bonded to fuel during the combustion process, and nitrogen contained in combustion air. Thermal NOx generated by liberation at high temperatures and Prompt NOx generated rapidly when hydrocarbon-based fossil fuels are exposed to high temperatures at high concentrations it can.
Nitrogen oxides (NOx) have a negative impact on the atmospheric environment and human life, so low NOx burner technology has been developed for some time. The generations are as follows.

  (1) First generation: The first generation low NOx technology is the air staging technology, which is representative of air staging. The rapid oxidation reaction by the fuel of the fuel is prevented and the flame temperature is lowered, thereby reducing the thermal NOx.

  (2) Second generation: The second generation low NOx technology is representative of gas staging technology, with a central part (about 5% to 25%) and an outer part (75% to 95%). ) In order to suppress the oxidation reaction of the outer part, which occupies most of the flame, so that the flame temperature does not increase Therefore, the generation of thermal NOx is reduced. Prompt NOx may be generated due to the air shortage of the outer flame, but the flame holding function and prompt NOx (Prompt NOx) can be generated by spraying to the periphery so that the flame temperature is 1000 ° C. or less. ) Can be implemented at the same time.

  (3) Third generation: The third generation low NOx technology is IFGR (Internal Free Gas Recirculation), and the combustion gas that has been primarily burned in the combustion chamber performs self-recirculation (Recirculation) in the combustion chamber. By doing so, the combustion gas is mixed with the flame so that the flame temperature can be lowered and thermal NOx can be reduced.

  In such third generation low NOx technology, the present applicant has proposed a high-efficiency low NOx type combustion head and a burner using the same of Korean Patent No. 10-1466809. Korean Registered Patent No. 10-1466809 introduces Knox (NOx) by inducing eddy currents from the combustion head, improving fuel and air mixing characteristics, burning the fuel, and allowing the combustion gas to self-recirculate. ) Is greatly reduced.

  In addition, by applying gas staging combustion technology to IFGR technology, a low NOx burner that can further reduce the amount of NOx generated by linking low NOx technology divided by generation is registered in Korea. It has been proposed in Japanese Patent No. 10-1569455.

Korean Registered Patent No. 10-1466809 (Registration Date: 2014.11.24.) Korean Registered Patent No. 10-1569455 (Registration Date: 2015.11.10.)

  It is an object of the present invention to improve a conventional combined low NOx burner, and to apply a gas staging combustion technique to the improved IFGR technique to further increase the amount of NOx generated. It is to provide a composite low NOx burner that reduces.

  In order to achieve the above object, a composite low NOx burner according to the present invention is a composite low NOx burner installed in a burner mounting hole of a combustion chamber, and is inserted into the burner mounting hole and the tip thereof is in the combustion chamber. A tube that is exposed and guides air to the combustion chamber, and at least one tube is provided at the end of the tube to form a split flame by injecting fuel into the combustion chamber. A fuel spud in which a first gas inlet for gas inflow is formed, and an inflow of combustion gas mixed with air inside the tube from the first gas inlet to the rear side of the combustion chamber A second gas inlet for is formed at the outer periphery of the tube.

  At the second gas inlet, a combustion gas guide is formed obliquely along the air flow direction.

  The fuel spud is branched from the fuel supply pipe and is arranged at a distance from the first spud pipe extending outside the tube, and forms a first gas inlet and is inserted inside the tube. And a second spud tube that is disposed and forms a split flame.

  The fuel spud is branched from the fuel supply pipe and is disposed outside the tube, and is spaced from the first spud pipe and forms a first gas inlet, and is disposed outside the tube. And a second spud tube that forms a split flame.

  An end of the first spud pipe is provided with an injection connecting portion having a reduced diameter in order to inject fuel toward the second spud pipe. In the second spud pipe, an end portion on the first gas inflow side is formed with a diameter expansion portion whose diameter is expanded toward the first spud pipe.

  According to the present invention, by combining the gas staging technology with the improved IFGR technology burner that effectively performs the self-recirculation of the combustion gas, the present invention is more effective than the low NOx burner to which the existing IFGR technology is applied. Has the effect of further reducing the amount of NOx generated.

It is a sectional side view which shows the state in which the composite type low NOx burner which concerns on 1st Example of this invention was installed in the combustion chamber. It is a perspective view which cut | disconnects and shows a part of edge part of the tube of FIG. FIG. 3 is an operational state diagram showing the flow of air, fuel gas, and combustion gas in the composite low NOx burner according to the first embodiment of the present invention. It is drawing which shows the flow of the gas between the fuel nozzle of FIG. 1, and a diffuser. It is drawing which shows the gas flow in case there exists a level | step difference between the fuel nozzle and diffuser of FIG. It is a flow conceptual diagram regarding the composite type low NOx burner which concerns on 1st Example of this invention. It is a sectional side view which shows the state by which the composite type low NOx burner which concerns on 2nd Example of this invention was installed in the combustion chamber. It is a perspective view which cut | disconnects and shows a part of edge part of the tube of FIG. It is a flow conceptual diagram regarding the composite type low NOx burner which concerns on 2nd Example of this invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, in the attached drawings, it should be noted that the same components are denoted by the same reference numerals as much as possible. Further, detailed descriptions of known functions and configurations that are determined to obscure the subject matter of the present invention are omitted. For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings.

  A tube is inserted on one side of the combustion chamber described in this specification, and is supplied with fuel and air, and an exhaust pipe is formed on the other side of the combustion chamber so that the burned combustion gas is discharged. can do. However, the exhaust pipe and its surrounding structures are not the core part of the present invention, and illustration and explanation thereof are omitted.

  The tube and the burner described in the present specification can be expressed by a conceptual cross-sectional view, omitting illustration and description of added components. However, it is omitted for the sake of explanation and understanding regarding the present invention, and is not limited to the drawings and explanations showing the structure and connection relationship of the tube and the burner according to the embodiment.

  FIG. 1 is a side sectional view showing a state in which a composite low NOx burner according to a first embodiment of the present invention is installed in a combustion chamber, and FIG. 2 is a partial cut of the end of the tube of FIG. It is a perspective view shown. As illustrated, the composite low NOx burner 100 according to the first embodiment of the present invention is inserted into the burner mounting hole (HL) of the combustion chamber (FR) and fixed by the mounting plate (MP), A tube 110 for guiding air to a combustion chamber (FR) surrounded by a wall (WL), a diameter smaller than the diameter of the tube 110, a side diameter portion 111 formed at the tip of the tube 110, and the inside of the tube 110 A fuel supply pipe 120 for supplying fuel, and a diffuser 130 for diffusing air guided by the tube 110, coupled to the tip of the fuel supply pipe 120 so that the outer periphery is arranged away from the inner wall of the tube 110, And the fuel supplied by the fuel supply pipe 120 to the tip of the fuel supply pipe 120 and the inner wall of the tube 110. It includes a plurality of fuel injection pipes 140 for injected toward the air passing between the Ifuyuza 130 periphery.

  In addition, at least one tube 110 is provided at the end of the tube 110 and has a pipe shape in which fuel is injected into the combustion chamber to form a divided flame, and a first gas flow for inflow of combustion gas is formed in a region of the outer periphery. A fuel spud 150 is provided in which an inlet 151 is formed. A second gas inlet 112 for inflow of combustion gas mixed with the air inside the tube 110 is formed at the outer peripheral edge of the tube at the rear side of the combustion chamber from the first gas inlet 151. Further, it further includes a blower 115 coupled to the tube 110 and forcibly supplying external air into the tube 110.

  The side diameter portion 111 is bent and formed with a gentle inclination toward the protruding portion 124 of the fuel supply pipe 120 protruding from the diffuser 130. As a result, the air flow rate from the air supply passage 161 formed at the interval (d1) between the outer peripheral edge of the diffuser 130 and the side diameter portion 111 toward the diffuser 130 becomes narrow, thereby increasing the air flow rate. be able to. Air is supplied to the diffuser 130 through the supply passage 161. At this time, fuel is injected through the fuel injection pipe 140 to form a flame.

  The end portion of the tube 110 forms a diameter expansion portion 116 having a diameter expanded from an intermediate portion 114 where a first spud pipe (described later) of the fuel spud 150 is disposed. A combustion gas guide 113 is formed at the second gas inlet 112 obliquely along the air flow direction, and the combustion gas in the combustion chamber is recirculated inside the intermediate portion 114 of the tube 110. The combustion gas guide portion 113 is preferably formed in a nozzle shape having a smaller diameter on the outlet side than on the inlet side, and the combustion gas preferably flows into the tube 110.

  Inside the fuel supply pipe 120, a central air injection pipe 121 that injects external air from the tip of the fuel supply pipe 120 in the axial direction (S) of the fuel supply pipe 120 is disposed. Such a central air injection pipe 121 prevents the flame from being concentrated at the center of the flame by increasing the diameter of the flame due to the injected air. As a result, the temperature at the center of the flame is prevented from rising excessively, and the amount of thermal NOx generated is reduced. The air that has passed through the central air injection pipe 121 is injected into the combustion chamber (FR) through an air injection port formed in the center of the diffuser 130, and the air injection port is smaller than the inner diameter of the central air injection pipe 121. Preferably it is formed. As shown in the flow conceptual diagram of FIG. 5, the central air injection pipe 121 can be removed.

  The diffuser 130 has a disk shape (disk type) and includes a plurality of air holes 131 for injecting air supplied through the air supply passage 161 to the combustion chamber (FR). The air hole 131 supplies air to the center of the flame, or when the diameter of the diffuser 130 increases as the burner capacity increases, the auxiliary flame for improving the flame holding property of the flame formed from the diffuser 130 Is provided. By arranging the air holes 131 and the nozzles of the fuel injection pipe 140 at a certain angle, the amount and pressure of air discharged from the air holes 131 are uniform with respect to the end of the entire plate of the diffuser 130. When mixing with the fuel injected from the nozzle, it can be expected that the mixing ratio of fuel and air is also uniform.

  The fuel injection pipe 140 is arranged radially from the end of the fuel supply pipe 120 and includes a fuel nozzle 141 for ejecting fuel in a direction orthogonal to the air supplied through the air supply passage 161. The fuel injected from the fuel nozzle 141 intersects with the air discharged through the air supply passage 161 at an angle close to approximately 90 degrees. As a result, the fuel is injected and rapidly mixed with the air supplied through the air supply passage 161, then forms a flame, and is guided by the air guided to the radial center of the combustion chamber FR through the side diameter portion 111. Can form a flame that concentrates in the center. At this time, after the flame is concentrated in the central part, it is dispersed to form a drum-shaped region, and the width of the region is narrow and the pressure is reduced, so that the combustion gas is guided to the drum-shaped region and the combustion gas is self-regenerated. Start to circulate.

  In the first embodiment, the end of the fuel injection pipe 140 in the radial direction and the outer peripheral edge of the diffuser 130 are at the same position as shown in FIG. 4a, but are injected from the fuel injection pipe 140 as shown in FIG. 4b. A gap (gap, d2) is formed between the end of the fuel injection pipe 140 and the edge of the diffuser 130 plate so that the fuel is rapidly mixed with the air supplied through the air supply passage 161. Can do. The length of the gap (gap, d2) can be set to 0.1% to 50% of the nozzle diameter of the fuel injection pipe 140.

  If the end of the fuel injection pipe 140 is formed to be smaller than the outer peripheral end of the diffuser 130, the air discharged through the air supply passage 161 can cause a vortex at the outer peripheral end of the diffuser 130. It becomes possible to mix rapidly. This will be described in more detail with reference to FIGS. 4a and 4b.

  FIG. 4 a shows a case where the length of the fuel injection pipe 140 is the same as the outer peripheral end of the diffuser 130, and FIG. 4 b shows a case where the length of the fuel injection pipe 140 does not reach the outer peripheral end of the diffuser 130. In FIG. 4a, since the air discharged from the air supply passage 161 to the combustion chamber has a straight traveling property, a vortex is not formed at the end of the fuel injection pipe 140, and a straight traveling air flow flows. On the other hand, referring to FIG. 4b, the outer peripheral end of the diffuser 130 and the end of the fuel injection pipe 140 form a step (d2), and the air from the supply passage 161 toward the combustion chamber diffuses into the region where the step occurs. Thus, a vortex can be formed. Thereby, the fuel injected from the fuel injection pipe 140 can be rapidly mixed with the air supplied through the air supply passage 161. The structure of the diffuser 130 of FIG. 4b improves fuel combustibility by using a vortex to rapidly mix fuel and air.

  Through the above-described process, the fuel and air are rapidly mixed and burned to form a drum-shaped flame, the combustion gas (S3) is induced in the drum-shaped region (S1), and the combustion gas (S3) is the first. By recirculation (P1, P2) through the gas inlet 151 and the second gas inlet 112, the temperature of the combustion gas is lowered, and at the same time, the fuel is supplied to the excessive fuel region (S2), and thermal NOx (Thermal NOx). ) And Prompt NOx (see FIG. 5).

  The fuel spud 150 is branched from the fuel supply pipe 120, and extends from the intermediate portion 114 of the tube 110 and extends outward. The fuel spud 150 is disposed at a distance from the first spud pipe 152. The gas inlet 151 is formed, and the second spud pipe 153 is formed by being inserted from the diameter expansion portion 116 through the inside of the tube 110 and forming a divided flame. An end of the first spud pipe 152 is provided with an injection connecting portion 154 having a reduced diameter in order to inject fuel toward the second spud pipe 153. In the second spud pipe 153, a diameter expansion part (153 a) whose diameter is expanded toward the first spud pipe 152 is formed at the end on the first gas inflow port 151 side.

  In the first embodiment of the present invention, the gas staging method is applied through the first gas inlet 151 and the second gas inlet 112 so that the temperature of the main flame generated from the combustion head is lowered. The thermal NOx can be controlled by lowering the temperature of the main flame and the split flame, that is, the temperature of the entire “flame group”. In the following, a description will be given of reducing the temperature of the flame group by combining the gas staging method with IFGR.

  FIG. 3 is an operational state diagram showing the flow of air, fuel gas, and combustion gas in the composite low NOx burner according to the first embodiment of the present invention, and FIG. 5 is a composite state according to the first embodiment of the present invention. As a flow conceptual diagram regarding the type low NOx burner, a flow conceptual diagram in the length direction from the portion where the fuel spud is located in the diffuser is shown.

  As shown in FIG. 3, an air flow (A1) is formed through the central air injection pipe 121, toward the center of the combustion chamber (FR), and a fuel gas flow (B1) is formed through the fuel supply pipe 120, This is injected from the fuel injection pipe 140 to form a main flame. On the other hand, a fuel gas flow (B2) is supplementarily formed through the fuel spud 150 branched from the fuel supply pipe 120, and this is injected to form a divided flame.

  At this time, an air flow (C1) is formed in the tube 110 by the operation of the blower 115, and the combustion gas flow (P2) formed by circulating the combustion gas in the combustion chamber (FR) is the second. The gas flows into the tube 110 through the gas inlet 112. The flow of air and the flow of combustion gas (C1 + P2) flowing into the tube 110 generate a main flame.

  A combustion gas flow (P1) formed by circulating the combustion gas in the combustion chamber (FR) flows into the second spud pipe 153 of the fuel spud 150 through the first gas inlet 151, and the combustion gas flow (P1). And the flow of fuel gas (B2) through the first spud tube 152 of the fuel spud 150 generates a split flame.

  The main flame formed through the diffuser 130 and the divided flame generated from the fuel spud 150 can form one “flame group”. The flame group formed by the diffuser 130 and the fuel spud 150 increases the surface area of the flame inside the combustion chamber (FR), and promotes the absorption of radiant heat on the heat transfer surface of the combustion chamber (FR). The temperature can be lowered. Further, the pressure around the split flame can be lowered by the fuel injected from the fuel spud 150 at a high speed. As a result, the combustion gas (S3) primarily combusted in the combustion chamber (FR) is attracted to the periphery of the low pressure diffuser 130 and the fuel spud 150, and this is caused by the self-combustion of the combustion gas (S3) inside the combustion chamber (FR). Recirculation can be induced. When the combustion gas (S3) self-recirculates in the direction of the fuel spud 150 in the combustion chamber (FR), the fuel spud 150 flows a part of the combustion gas (S3) into the fuel spud 150, and the fuel spud 150 The calorific value of the fuel injected from 150 can be reduced. This can be expected to lower the temperature of the entire flame group.

  The fuel spud 150 is divided into a first spud pipe 152 and a second spud pipe 153, and the first gas flow is caused by the injection pressure when fuel is injected from the first spud pipe 152 to the second spud pipe 153. The pressure around the inlet 151 decreases, and the combustion gas (S3) is attracted and flows into the first gas inlet 151 having a low pressure. That is, when high-pressure fuel is injected from the fuel injection port of the second spud pipe, the pressure around the fuel injection port, for example, the first gas inlet 151 and the periphery thereof, is lower than the injection pressure of the fuel injection port. Due to such a pressure difference, the combustion gas (S3) moves toward the first gas inlet 151 inside the combustion chamber (FR), and the combustion gas (S3) moves to cause the combustion gas. (S3) can perform self-recirculation inside the combustion chamber (FR).

  As the combustion gas (S3) is attracted to the first gas inlet 151, the fuel injected from the fuel injection port of the second spud pipe 153 becomes a mixture of “fuel + combustion gas (S3)”, and the air Instead, when the combustion gas flows into the second spud pipe 153, the combustibility of the fuel is lower than when the air and the fuel come into contact with each other, and this has the effect of lowering the temperature of the divided flame generated from the fuel spud 150. is there. When the temperature of the divided flame is lowered, the temperature of the flame group injected from the diffuser 130 and the fuel spud 150 is lowered, which can reduce the thermal NOx generated from the flame group.

  In addition, the fuel and air injected through the diffuser 130 increase the surface area of the flame inside the combustion chamber (FR) by the combustion gas flowing in through the second gas inlet 112, and the heat transfer surface of the combustion chamber (FR). By promoting absorption of radiant heat, the temperature of the flame group can be lowered. That is, the combustion gas (S3) primarily burned in the combustion chamber (FR) is attracted to the periphery of the low-pressure diffuser 130 and the fuel spud 150, and then flows into the tube 110 through the second gas inlet 112, and burns. Self-recirculation of gas (S3) can be induced. When the combustion gas (S3) self-recirculates in the combustion chamber (FR) in the direction of the fuel spud 150, a part of the combustion gas (S3) flows into the tube 110 through the second gas inlet 112, and the amount of air By lowering the relative value, the effect of lowering the temperature of the entire flame group can be expected.

  When the air supplied from the blower 115 flows to the combustion gas guide 113 of the tube 110, the pressure around the second gas inlet 112 decreases due to the fluid air pressure, and the combustion gas (S3) has a low pressure. The combustion gas (S3) is attracted to the inlet 112 and flows, and the combustion gas (S3) increases the self-recirculation force inside the combustion chamber (FR) due to the movement of the combustion gas (S3).

  When the combustion gas (S3) is attracted to the second gas inlet 112, the air in the tube 110 becomes a mixture of “air + combustion gas (S3)”, and the amount of air decreases and the combustibility of the fuel decreases. This has the effect of lowering the temperature of the main flame generated from the fuel spud 150. When the temperature of the main flame is lowered, the temperature of the flame group injected from the diffuser 130 and the fuel spud 150 is lowered, and this can further reduce the thermal NOx generated from the flame group.

  FIG. 6 is a side sectional view showing a state in which the composite low NOx burner 200 according to the second embodiment of the present invention is installed in the combustion chamber, and FIG. 7 is a partial cut of the end of the tube of FIG. FIG. 8 is a flow conceptual diagram relating to a composite low NOx burner according to a second embodiment of the present invention.

  In the composite low NOx burner 200 of the second embodiment, the fuel spud 250 is branched from the fuel supply pipe 220 and is spaced apart from the first spud pipe 252 and the first spud pipe 252 that extend outside the tube 210. A first gas inlet 251 forming a combustion gas flow (P1) disposed and recirculated, and a second spud tube 253 disposed outside the tube 210 and forming a split flame.

  From the first gas inlet 251 to the rear in the outer direction of the combustion chamber, a second flow that forms a combustion gas flow (P2) that is recirculated for the inflow of the combustion gas mixed with the air inside the tube 210 is formed. A gas inlet 212 is formed at the outer periphery of the tube.

  The remaining configurations, operations, and effects of the tube 210, the blower 215, the fuel supply pipe 220, the central air injection pipe 221, the diffuser 230, the fuel injection pipe 240, and the like of the second embodiment are the same as or similar to those of the first embodiment. Therefore, detailed description is omitted.

  On the other hand, the embodiments of the present invention disclosed in the present specification and the drawings merely explain specific examples in order to explain the technical contents of the present invention in an easy-to-understand manner and to help understand the present invention. It does not limit the range. It will be apparent to those skilled in the art to which the present invention pertains that other modified examples based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein. It is.

100, 200: Composite type low NOx burner 110: Tube 111: Side diameter portion 112: Second gas inlet 113: Combustion gas guide portion 120: Fuel supply pipe 121: Central air injection pipe 140: Fuel injection pipe 141: Fuel nozzle 150: fuel spud 151: first gas inlet 152: first spud pipe 153: second spud pipe 161: air supply passage FR: combustion chamber HL: burner mounting hole MP: mounting plate

Claims (6)

A combined low NOx burner installed in the burner mounting hole of the combustion chamber,
A tube that is inserted into the burner mounting hole and the tip is exposed to the combustion chamber, and guides air to the combustion chamber;
At least one end provided on the end of the tube is a pipe shape that injects fuel into the combustion chamber to form a divided flame, and a first gas inlet for inflow of combustion gas in a region of the outer periphery Formed with a fuel spud, and
A second gas inlet for inflow of combustion gas mixed with the air inside the tube is formed at the outer peripheral edge of the tube at the rear side of the combustion chamber from the first gas inlet. A combined low NOx burner characterized by the above.   2. The composite low NOx burner according to claim 1, wherein a combustion gas guide portion is formed obliquely along the air flow direction at the second gas inlet. The fuel spud is
A first spud pipe branched from the fuel supply pipe and extended outside the tube;
And a second spud tube disposed at a distance from the first spud tube, forming the first gas inlet, and being inserted and disposed inside the tube, and forming a divided flame. The composite low NOx burner according to claim 1. The fuel spud is
A first spud pipe branched from the fuel supply pipe and extended outside the tube;
And a second spud tube disposed at a distance from the first spud tube, forming the first gas inlet, and disposed outside the tube to form a divided flame. Item 4. A combined low NOx burner according to Item 1.   The end portion of the first spud pipe is provided with an injection connecting portion having a reduced diameter in order to inject fuel toward the second spud pipe. 2. A composite low NOx burner described in 1.   4. The diameter of the second spud pipe, wherein the end on the first gas inflow side is formed with a diameter expanding portion whose diameter is expanded toward the first spud pipe. Item 5. A combined low NOx burner according to Item 4.

Images