Regenerative burner and metal melting furnace equipped with same

Abstract

To provide a regenerative burner enabling simplification of a configuration of the entire burner and simplification of a configuration related to flame detection while maintaining high combustion efficiency, and a metal melting furnace including the regenerative burner.SOLUTION: A regenerative burner includes a control device S. The control device executes alternate combustion control in a form of injecting high-pressure air Ah from one high-pressure air nozzle Na1 and stopping injection of the high-pressure air Ah from the other high-pressure air nozzle Na2 while fuel gas F is being injected from a fuel gas nozzle Nb in a first flowing state and stopping the injection of the high-pressure air Ah from one high-pressure air nozzle Na1 and injecting the high-pressure air Ah from the other high-pressure air nozzle Na2 while the fuel gas F is being injected from the fuel gas nozzle Nb in a second flowing state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a regenerative burner that has a pair of heat storage bodies and is capable of switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other heat storage body, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other heat storage body, and is capable of forming a flame by alternately burning the combustion air and fuel gas heated in the first flow state or the second flow state, and a metal melting furnace equipped with the regenerative burner. [Background technology]

[0002] Conventionally, as shown in Patent Document 1, a known regenerative burner is one that includes a heat storage body provided in a pair of heat storage chambers for recovering exhaust heat from the combustion exhaust gas, a burner including a pair of fuel gas nozzles to which heated combustion air is supplied via the pair of heat storage bodies, and a pair of fuel gas supply passages that supply fuel gas separately to each of the pair of fuel gas nozzles. In this regenerative burner, alternating combustion is performed by switching between a first combustion state in which heated combustion air is supplied to one of the paired fuel gas nozzles via one of the paired heat storage bodies and fuel gas is supplied via one of the paired fuel gas supply channels for combustion, and a second combustion state in which heated combustion air is supplied to the other of the paired fuel gas nozzles via the other of the paired heat storage bodies and fuel gas is supplied via the other of the paired fuel gas supply channels for combustion. In the above-described regenerative burner, alternating combustion is performed in such a way that the heat storage medium that recovers the exhaust heat of the combustion exhaust gas heats the combustion air, so that the space to be heated can be heated with high combustion efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-274432 Summary of the Invention [Problem to be solved by the invention]

[0004] The regenerative burner shown in Patent Document 1 has separate fuel gas supply passages for supplying fuel gas to each of the paired fuel gas nozzles, and also has separate auxiliary equipment such as on-off valves for opening and closing each of the fuel gas supply passages. Although not described in detail, a pilot nozzle is usually required in addition to the paired fuel gas nozzles, resulting in a problem of increased device size. Furthermore, a flame detection sensor for detecting a flame must be provided for each fuel gas nozzle, and control based on this detection must also be performed separately for each burner, complicating control and leaving room for improvement.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a regenerative burner that can maintain high combustion efficiency while simplifying the overall burner configuration and the configuration related to flame detection, and a metal melting furnace equipped with the same. [Means for solving the problem]

[0006] The regenerative burner to achieve the above purpose is as follows: A regenerative burner is provided with a pair of heat storage bodies, and is capable of forming a flame by alternately controlling the combustion air and fuel gas heated in the first flow state or the second flow state by switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other of the heat storage bodies, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other of the heat storage bodies, and characterized by: The combustion chamber includes only a single fuel gas nozzle provided at the tip of the fuel gas pipe as a nozzle for injecting fuel gas into the combustion space, a pair of high-pressure air nozzles for injecting high-pressure air having a pressure higher than atmospheric pressure into the combustion space in different directions from each other, a direction in which the high-pressure air is sprayed from the pair of high-pressure air nozzles is set in a direction in which the fuel gas sprayed from the fuel gas nozzle can be drawn into the flow of high-pressure air; a control device that executes the alternating combustion control by injecting high-pressure air from one of the high-pressure air nozzles while injecting fuel gas from the fuel gas nozzle in the first flow state and stopping the injection of high-pressure air from the other high-pressure air nozzle, and by stopping the injection of high-pressure air from one of the high-pressure air nozzles while injecting fuel gas from the fuel gas nozzle in the second flow state; 、 a pipe axis of the pair of high-pressure air nozzles is aligned with a pipe axis of the fuel gas nozzle, and the pair of high-pressure air nozzles are provided so as to sandwich the fuel gas nozzle; a fuel gas injection hole for injecting fuel gas from the fuel gas nozzle is formed only on a side circumferential surface of the fuel gas nozzle excluding a tip end thereof, High-pressure air injection holes for injecting high-pressure air from the high-pressure air nozzle are formed only on the side circumferential surface of the high-pressure air nozzle excluding the tip. It's at the point.

[0007] According to the above-mentioned characteristic configuration, firstly, a so-called self-pilot system is adopted in which fuel gas is supplied to the combustion space by a single fuel gas nozzle. Therefore, compared to the conventional configuration in which fuel gas is supplied to the combustion space by a pair of fuel gas nozzles via a pair of fuel gas flow passages and a pilot flow passage, the configuration related to the supply of fuel gas can be simplified and made smaller. Furthermore, with this configuration, it is only necessary to detect the flame formed by the fuel gas injected from a single fuel gas nozzle, and therefore the configuration for flame detection can be simplified compared to conventional configurations that detect the flame formed by the fuel gas injected from a pair of fuel gas nozzles. Typically, in a regenerative burner that performs alternating combustion, in order to separately realize a first flow state in which combustion exhaust gas is guided to one of a pair of regenerative heat storage bodies and a second flow state in which combustion exhaust gas is guided to the other, the flow direction of the combustion exhaust gas in the first flow state (direction in which flame is formed) is configured to be different from the flow direction of the combustion exhaust gas in the second flow state (direction in which flame is formed). However, in a configuration that has only a single fuel gas nozzle, as in the above-mentioned characteristic configuration, it is difficult to make the flow direction of the combustion exhaust gas in the first flow state different from the flow direction of the combustion exhaust gas in the second flow state. Therefore, according to the above characteristic configuration, a pair of high-pressure air nozzles are provided as combustion air nozzles that inject high-pressure air at a pressure higher than atmospheric pressure into the combustion space, and the direction of injection of the high-pressure air from the pair of high-pressure air nozzles is set in a direction that allows the fuel gas injected from the fuel gas nozzle to be drawn into the flow of high-pressure air, and the control device injects high-pressure air from one of the high-pressure air nozzles while injecting fuel gas from the fuel gas nozzle in the first flow state and stops injection of high-pressure air from the other high-pressure air nozzle, and injects fuel gas from the fuel gas nozzle in the second flow state and stops injection of high-pressure air from one of the high-pressure air nozzles while injecting high-pressure air from the other high-pressure air nozzle, so that alternating combustion control can be performed well even with a configuration that includes only a single fuel gas nozzle. This allows the combustion exhaust gas to flow through one of the pair of heat storage bodies in the first flow state, and the combustion exhaust gas to flow through the other of the pair of heat storage bodies in the second flow state, thereby enabling alternating combustion to be carried out effectively. Furthermore, according to the above characteristic configuration, the pipe axis of the paired high-pressure air nozzles is aligned with the pipe axis of the fuel gas nozzle, and the paired high-pressure air nozzles are arranged in a manner that sandwiches the fuel gas nozzle.Therefore, when fuel is being sprayed from a single fuel gas nozzle, combustion in the first flow state can be achieved, for example, by directing the spray direction of high-pressure gas from one high-pressure nozzle toward the other heat storage body, and combustion in the second flow state can be achieved by directing the spray direction of high-pressure gas from the other high-pressure nozzle toward the other heat storage body. Therefore, a regenerative burner capable of appropriately performing alternating combustion can be realized with a simple configuration in which a single fuel gas nozzle is shared in common between the first flow state and the second flow state. Furthermore, regenerative burners are usually arranged with the tube axis of the fuel gas nozzle facing the center of the furnace. However, when used in a metal melting furnace, for example, if a fuel gas outlet is provided at the tip of the fuel gas nozzle, the combustion flame is formed by colliding with the outer wall surface of the crucible or the like inside the metal melting furnace, and the part of the molten metal furnace that the flame collides with is easily damaged. According to the above-described characteristic configuration, the fuel gas injection holes for injecting fuel gas from the fuel gas nozzle are formed only on the circumferential side surface excluding the tip of the fuel gas nozzle, and the high-pressure air injection holes for injecting high-pressure air from the high-pressure air nozzle are formed only on the circumferential side surface excluding the tip of the high-pressure air nozzle. Therefore, even when the tube axes of the fuel gas nozzle and the high-pressure air nozzle are arranged toward the center of the furnace, the flame is formed in a direction intersecting the tube axis, thereby preventing damage caused by the flame locally impinging on part of the outer wall surface of the crucible or the like inside the metal melting furnace. Furthermore, by alternately injecting high-pressure air from high-pressure air injection holes formed only on the side circumferential surface of the paired high-pressure air nozzles excluding the tips thereof, the paired flames in the first flow state and the second flow state can be formed in relatively significantly different directions compared to when injection holes are provided at the tips of the high-pressure air nozzles, thereby achieving good alternating combustion.

[0012] The regenerative burner to achieve the above purpose is as follows: A regenerative burner is provided with a pair of heat storage bodies, and is capable of forming a flame by alternately controlling the combustion air and fuel gas heated in the first flow state or the second flow state by switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other of the heat storage bodies, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other of the heat storage bodies, and characterized by: The combustion chamber includes only a single fuel gas nozzle provided at the tip of the fuel gas pipe as a nozzle for injecting fuel gas into the combustion space, a pair of high-pressure air nozzles for injecting high-pressure air having a pressure higher than atmospheric pressure into the combustion space in different directions from each other, a direction in which the high-pressure air is sprayed from the pair of high-pressure air nozzles is set in a direction in which the fuel gas sprayed from the fuel gas nozzle can be drawn into the flow of high-pressure air; a control device that executes the alternating combustion control by injecting high-pressure air from one of the high-pressure air nozzles and stopping the injection of high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the first flow state, and by stopping the injection of high-pressure air from one of the high-pressure air nozzles and injecting high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the second flow state, a pipe axis of the pair of high-pressure air nozzles is aligned with a pipe axis of the fuel gas nozzle, and the pair of high-pressure air nozzles are provided so as to sandwich the fuel gas nozzle; The fuel gas nozzle has a fuel gas injection hole for injecting fuel gas from the fuel gas nozzle and a high-pressure air injection hole for injecting high-pressure air from the high-pressure air nozzle, and the fuel gas injection hole is provided at a different position in the pipe axis direction along the pipe axis of the fuel gas nozzle.

[0013] According to the above-mentioned characteristic configuration, firstly, a so-called self-pilot system is adopted in which fuel gas is supplied to the combustion space by a single fuel gas nozzle. Therefore, compared to the conventional configuration in which fuel gas is supplied to the combustion space by a pair of fuel gas nozzles via a pair of fuel gas flow passages and a pilot flow passage, the configuration related to the supply of fuel gas can be simplified and made smaller. Furthermore, with this configuration, it is only necessary to detect the flame formed by the fuel gas injected from a single fuel gas nozzle, and therefore the configuration for flame detection can be simplified compared to conventional configurations that detect the flame formed by the fuel gas injected from a pair of fuel gas nozzles. Typically, in a regenerative burner that performs alternating combustion, in order to separately realize a first flow state in which combustion exhaust gas is guided to one of a pair of regenerative heat storage bodies and a second flow state in which combustion exhaust gas is guided to the other, the flow direction of the combustion exhaust gas in the first flow state (direction in which flame is formed) is configured to be different from the flow direction of the combustion exhaust gas in the second flow state (direction in which flame is formed). However, in a configuration that has only a single fuel gas nozzle, as in the above-mentioned characteristic configuration, it is difficult to make the flow direction of the combustion exhaust gas in the first flow state different from the flow direction of the combustion exhaust gas in the second flow state. Therefore, according to the above characteristic configuration, a pair of high-pressure air nozzles are provided as combustion air nozzles that inject high-pressure air at a pressure higher than atmospheric pressure into the combustion space, and the direction of injection of the high-pressure air from the pair of high-pressure air nozzles is set in a direction that allows the fuel gas injected from the fuel gas nozzle to be drawn into the flow of high-pressure air, and the control device injects high-pressure air from one of the high-pressure air nozzles while injecting fuel gas from the fuel gas nozzle in the first flow state and stops injection of high-pressure air from the other high-pressure air nozzle, and injects fuel gas from the fuel gas nozzle in the second flow state and stops injection of high-pressure air from one of the high-pressure air nozzles while injecting high-pressure air from the other high-pressure air nozzle, so that alternating combustion control can be performed well even with a configuration that includes only a single fuel gas nozzle. This allows the combustion exhaust gas to flow through one of the pair of heat storage bodies in the first flow state, and the combustion exhaust gas to flow through the other of the pair of heat storage bodies in the second flow state, thereby enabling alternating combustion to be carried out effectively. Furthermore, according to the above characteristic configuration, the pipe axis of the paired high-pressure air nozzles is aligned with the pipe axis of the fuel gas nozzle, and the paired high-pressure air nozzles are arranged in a manner that sandwiches the fuel gas nozzle.Therefore, when fuel is being sprayed from a single fuel gas nozzle, combustion in the first flow state can be achieved, for example, by directing the spray direction of high-pressure gas from one high-pressure nozzle toward the other heat storage body, and combustion in the second flow state can be achieved by directing the spray direction of high-pressure gas from the other high-pressure nozzle toward the other heat storage body. Therefore, a regenerative burner capable of appropriately performing alternating combustion can be realized with a simple configuration in which a single fuel gas nozzle is shared in common between the first flow state and the second flow state. Furthermore, According to the above characteristic configuration, the fuel gas injection hole for injecting fuel gas from the fuel gas nozzle and the high-pressure air injection hole for injecting high-pressure air from the high-pressure air nozzle are located at different positions in the pipe axial direction along the pipe axis of the fuel gas nozzle, which makes it difficult for the high-pressure air flow to collide with the fuel gas flow, thereby effectively suppressing the flame from going out.

[0014] According to a further characteristic configuration of the regenerative burner, Each of the paired high-pressure air nozzles is provided with a high-pressure air injection direction adjustment mechanism that can adjust the injection direction of high-pressure air from the high-pressure air injection hole by rotating and fixing the high-pressure air nozzle around the pipe axis.

[0015] According to the above-described characteristic configuration, the high-pressure air injection direction adjustment mechanism can adjust the injection direction of the high-pressure air from the high-pressure air injection hole by rotating and fixing the high-pressure air nozzle around the pipe axis. Therefore, it is possible to fine-tune the state of entrainment of the fuel gas flow into the paired high-pressure air flow in accordance with, for example, the output and air ratio, thereby more effectively adjusting the state of flame formation.

[0016] According to a further characteristic configuration of the regenerative burner, the fuel gas is injected from the fuel gas nozzle through a fuel gas injection hole, the fuel gas being injected in a vertically upward direction; The fuel gas supply system is provided with a flame detection means for detecting a flame engulfed below the fuel gas nozzle.

[0017] After extensive research, the inventors have newly discovered that in the regenerative burner described above, when the injection direction of fuel gas from the fuel gas injection hole that injects fuel gas from the fuel gas nozzle is set vertically upward, as in the characteristic configuration described above, a stable flame is formed on the opposite side of the injection direction of the fuel gas relative to the fuel gas nozzle (below the fuel gas injection hole). Therefore, by installing the flame detection means so as to detect the flame engulfed below the fuel gas nozzle, as in this configuration, it is possible to improve the accuracy of flame detection.

[0018] The regenerative burner to achieve the above purpose is as follows: A regenerative burner is provided with a pair of heat storage bodies, and is capable of forming a flame by alternately controlling the combustion air and fuel gas heated in the first flow state or the second flow state by switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other of the heat storage bodies, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other of the heat storage bodies, and characterized by: The combustion chamber includes only a single fuel gas nozzle provided at the tip of the fuel gas pipe as a nozzle for injecting fuel gas into the combustion space, a pair of high-pressure air nozzles for injecting high-pressure air having a pressure higher than atmospheric pressure into the combustion space in different directions from each other, a direction in which the high-pressure air is sprayed from the pair of high-pressure air nozzles is set in a direction in which the fuel gas sprayed from the fuel gas nozzle can be drawn into the flow of high-pressure air; a control device that executes the alternating combustion control by injecting high-pressure air from one of the high-pressure air nozzles and stopping the injection of high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the first flow state, and by stopping the injection of high-pressure air from one of the high-pressure air nozzles and injecting high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the second flow state, the high-pressure air nozzle is made of ceramic containing alumina as a main component; a pressure detection means for detecting the pressure inside the high-pressure air nozzle; When the pressure detected by the pressure detection means falls below a predetermined lower limit pressure of high-pressure air, the control device determines that damage to the high-pressure air nozzle has occurred and executes an alternating combustion stop process to stop the alternating combustion control.

[0019] According to the above-mentioned characteristic configuration, firstly, a so-called self-pilot system is adopted in which fuel gas is supplied to the combustion space by a single fuel gas nozzle. Therefore, compared to the conventional configuration in which fuel gas is supplied to the combustion space by a pair of fuel gas nozzles via a pair of fuel gas flow passages and a pilot flow passage, the configuration related to the supply of fuel gas can be simplified and made smaller. Furthermore, with this configuration, it is only necessary to detect the flame formed by the fuel gas injected from a single fuel gas nozzle, and therefore the configuration for flame detection can be simplified compared to conventional configurations that detect the flame formed by the fuel gas injected from a pair of fuel gas nozzles. Typically, in a regenerative burner that performs alternating combustion, in order to separately realize a first flow state in which combustion exhaust gas is guided to one of a pair of regenerative heat storage bodies and a second flow state in which combustion exhaust gas is guided to the other, the flow direction of the combustion exhaust gas in the first flow state (direction in which flame is formed) is configured to be different from the flow direction of the combustion exhaust gas in the second flow state (direction in which flame is formed). However, in a configuration having only a single fuel gas nozzle, as in the above-mentioned characteristic configuration, it is difficult to make the flow direction of the combustion exhaust gas in the first flow state different from the flow direction of the combustion exhaust gas in the second flow state. Therefore, according to the above characteristic configuration, a pair of high-pressure air nozzles are provided as combustion air nozzles that inject high-pressure air at a pressure higher than atmospheric pressure into the combustion space, and the direction of injection of the high-pressure air from the pair of high-pressure air nozzles is set in a direction that allows the fuel gas injected from the fuel gas nozzle to be drawn into the flow of high-pressure air, and the control device injects high-pressure air from one of the high-pressure air nozzles while injecting fuel gas from the fuel gas nozzle in the first flow state and stops injection of high-pressure air from the other high-pressure air nozzle, and injects fuel gas from the fuel gas nozzle in the second flow state and stops injection of high-pressure air from one of the high-pressure air nozzles while injecting high-pressure air from the other high-pressure air nozzle, so that alternating combustion control can be performed well even with a configuration that includes only a single fuel gas nozzle. This allows the combustion exhaust gas to flow through one of the pair of heat storage bodies in the first flow state, and the combustion exhaust gas to flow through the other of the pair of heat storage bodies in the second flow state, thereby enabling alternating combustion to be carried out effectively. Furthermore, According to the above-mentioned characteristic configuration, firstly, by forming the high-pressure air nozzle from a ceramic containing alumina as its main component and having a relatively high heat resistance, it is possible to improve the fire resistance performance against high-temperature flames. However, even such high-pressure air nozzles with high fire resistance can be damaged, and if damaged, there is a risk that combustion air will be ejected into the furnace when the regenerative burner is applied to a metal melting furnace. Therefore, as in the above characteristic configuration, when the pressure detected by the pressure detection means falls below a predetermined lower limit pressure of high-pressure air, the control device determines that damage to the high-pressure air nozzle has occurred and executes an alternating combustion stop process to stop the alternating combustion control, thereby realizing a regenerative burner with even greater safety.

[0020] The metal melting furnace has the following features to achieve the above objective: The above-mentioned regenerative burner is installed through the furnace wall of a cylindrical furnace, and with a pot or crucible placed inside the cylindrical furnace, a flame is formed along the inner surface of the furnace wall by the alternating combustion control.

[0021] According to the above characteristic configuration, the effects of the regenerative burner described above can be effectively exhibited, good alternating combustion can be achieved while adopting a simple configuration, and a highly durable metal melting furnace can be realized.

[0022] In the metal melting furnace described above, by providing a pair of heat storage bodies sandwiching the regenerative burner, alternating combustion control can be performed well. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a partial cross-sectional plan view of a metal melting furnace equipped with a regenerative burner according to an embodiment. [Figure 2] 2(a) is a longitudinal cross-sectional view of the regenerative burner according to the embodiment, and FIG. 2(b) is a cross-sectional view taken along the line bb in FIG. 2(a). [Figure 3] FIG. 2 is a view of the regenerative burner according to the embodiment as viewed in the axial direction from the tip end side. DETAILED DESCRIPTION OF THE INVENTION

[0024] The regenerative burner 100 according to an embodiment of the present invention and the metal melting furnace 200 equipped with the same are capable of maintaining high combustion efficiency while simplifying the overall burner configuration and the configuration related to flame detection. A regenerative burner 100 according to an embodiment and a metal melting furnace 200 equipped with the same will be described below with reference to FIGS.

[0025] As shown in FIGS. 1 to 3, the regenerative burner 100 according to this embodiment includes a pair of regenerative heat storage bodies T1 and T2 (T), and switches between a first flow state (flow state shown in FIG. 1) in which combustion exhaust gas E flows through one regenerative heat storage body T2 and main air Am as combustion air flows through the other regenerative heat storage body T1, and a second flow state (not shown) in which main air Am flows through one regenerative heat storage body T2 and combustion exhaust gas E flows through the other regenerative heat storage body T1. The metal melting furnace 200 according to this embodiment is capable of forming a flame by alternate combustion control of heated main air Am and fuel gas F in a flowing state. As shown in FIG. 1, the metal melting furnace 200 according to this embodiment has the above-mentioned regenerative burner 100 penetrating a bottomed cylindrical furnace wall 200a, and with a crucible 210 disposed inside the furnace wall 200a, alternate combustion control is used to form a pair of flames, one rotating to one side in the circumferential direction and the other rotating to the other side, along the inner surface 200b of the furnace wall 200a. Here, each of the pair of regenerative heat storage bodies T1 and T2 is provided to penetrate the furnace wall 200a in the cylindrical circumferential direction of the furnace wall 200a, and the regenerative burner 100 is provided between them. In other words, the pair of regenerative heat storage bodies T are provided with the regenerative burner 100 sandwiched between them. 1, the combustion exhaust gas E of the flame FL, which uses main air Am from the other regenerator T1 as combustion air, circulates along the inner circumferential surface of the furnace wall 200a of the metal melting furnace 200 and passes through one regenerator T2. Although not shown in the figure, the combustion exhaust gas E of the flame FL, which uses main air Am from one regenerator T2 as combustion air, circulates along the inner circumferential surface of the furnace wall 200a of the metal melting furnace 200 and passes through the other regenerator T1.

[0026] The regenerative burner 100 according to this embodiment has the following configuration in order to simplify the overall configuration of the burner while maintaining high combustion efficiency. The regenerative burner 100 includes a single fuel gas nozzle Nb provided at the tip of a fuel gas flow pipe Lx as a nozzle for injecting fuel gas F into a combustion space N of a metal melting furnace 200, and also includes a pair of high-pressure air nozzles Na1 and Na2 (Na) for injecting high-pressure air Ah (which also functions as combustion air) compressed by a compressor (not shown) and having a pressure higher than atmospheric pressure into the combustion space N in different directions. The injection direction of the high-pressure air Ah from the pair of high-pressure air nozzles Na is determined by drawing the fuel gas F injected from the fuel gas nozzle Nb into the flow of the high-pressure air Ah. The control device S is provided with a control unit S that performs alternating combustion control by spraying high-pressure air Ah from one high-pressure air nozzle Na1 and stopping the spray of high-pressure air Ah from the other high-pressure air nozzle Na2 while spraying fuel gas F from the fuel gas nozzle Nb in a first flow state (the flow state shown in FIG. 1), and by stopping the spray of high-pressure air Ah from one high-pressure air nozzle Na1 and spraying high-pressure air Ah from the other high-pressure air nozzle Na2 while spraying fuel gas F from the fuel gas nozzle Nb in a second flow state (not shown). In this embodiment, the combustion space N is a space formed between the furnace wall 200 a of the metal melting furnace 200 and the crucible 210 .

[0027] Further, to further explain the detailed configuration of the regenerative burner 100, as shown in Figures 1 and 2, it is equipped with an outer envelope L5 that surrounds the pair of high-pressure air nozzles Na1 and Na2 mentioned above, a first high-pressure air flow pipe L1 that guides high-pressure air Ah to one of the high-pressure air nozzles Na1, a second high-pressure air flow pipe L2 that guides high-pressure air Ah to the other high-pressure air nozzle Na2, a single fuel gas nozzle Nb, a fuel gas flow pipe Lx that guides fuel gas F to the fuel gas nozzle Nb, and a spark rod Sr that ignites a flame between the ground electrode D1 and the center electrode D2 provided at the tip side of the regenerative burner 100 (the tip side of arrow X in Figures 1 and 2) and at the tip of the fuel gas nozzle Nb. Incidentally, inside the outer envelope L5, a support plate W is provided at the tip side of the fuel gas nozzle Nb, which is perpendicular to the pipe axis P3 of the fuel gas nozzle Nb and passes through and supports the pair of high-pressure air flow pipes L1 and L2, and its outer diameter is the same as the inner diameter of the outer envelope L5. Furthermore, the support plate W is provided with a plurality of through holes Wa through which pilot air Ap, serving as combustion air flowing inside the outer casing L5, passes. The through holes Wa are provided at intervals around the center of the pipe axis P3 when viewed in a direction along the pipe axis P3 of the fuel gas nozzle Nb. Here, an ultraviolet sensor Suv is provided on the base end side of the regenerative burner 100 as a flame detection means for detecting the flame FL that is drawn in vertically below the fuel gas nozzle Nb, and the ultraviolet sensor Suv is arranged so as to detect the flame FL through a through hole Wa formed below the tube axis P3 of the support plate W when viewed in the direction of the tube axis P3 of the fuel gas nozzle Nb. The pilot air Ap continues to be supplied at a constant flow rate in both the first flow state and the second flow state of the alternating combustion control.

[0028] One of the high-pressure air pipes L1 is provided with a sixth solenoid valve V6 that opens and closes the high-pressure air pipe L1, and the other high-pressure air pipe L2 is provided with a first solenoid valve V1 that opens and closes the high-pressure air pipe L2. In the above-mentioned alternating combustion control, the control device S controls the sixth solenoid valve V6 to be in an open state and the first solenoid valve V1 to be in a closed state in the first flow state, and controls the sixth solenoid valve V6 to be in a closed state and the first solenoid valve V1 to be in an open state in the second flow state.

[0029] Incidentally, the paired high-pressure air nozzles Na1 and Na2 are exposed to the flame FL during the alternating combustion, and are therefore made of a ceramic whose main component is highly heat-resistant alumina (high-purity alumina (PTO)). However, even a high-pressure air nozzle Na made of such a material may be damaged. Therefore, in this embodiment, one of the high-pressure air flow pipes L1 is provided with a first pressure sensor Sp1 (an example of a pressure detection sensor) that detects the internal pressure of the high-pressure air flow pipe L1, and the other high-pressure air flow pipe L2 is provided with a second pressure sensor Sp2 (an example of a pressure detection sensor) that detects the internal pressure of the high-pressure air flow pipe L2.When the pressure detected by the first pressure sensor SP1 and the second pressure sensor Sp2 falls below a high-pressure air lower limit pressure that is predetermined, for example, for each output or furnace, the control device S determines that damage has occurred to the high-pressure air nozzle Na and executes an alternating combustion stop process that stops the alternating combustion control.

[0030] The fuel gas flow pipe Lx is connected to a main fuel flow pipe L4 through which main fuel Fm flows as fuel gas F, and a pilot fuel flow pipe L3 through which pilot fuel Fp flows as fuel gas F. The main fuel flow pipe L4 is provided with a fourth solenoid valve V4 and a fifth solenoid valve V5 for opening and closing the main fuel flow pipe L4, and the pilot fuel flow pipe L3 is provided with a second solenoid valve V2 and a third solenoid valve V3 for opening and closing the pilot fuel flow pipe L3. In the above-described alternating combustion control, the control device S controls the second solenoid valve V2 and the third solenoid valve V3, which control the flow of pilot fuel Fp, to be open in both the first flow state and the second flow state, including when switching between the two. On the other hand, the control device S controls the fourth solenoid valve V4 and the fifth solenoid valve V5, which control the flow of main fuel Fm, to be closed when switching between the first flow state and the second flow state, and to be open in both the first flow state and the second flow state except when switching.

[0031] Now, the regenerative burner 100 according to this embodiment has the following configuration to form a pair of flames FL in alternating combustion by drawing in fuel gas F injected from the fuel gas nozzle Nb using high-pressure air Ah injected from the pair of high-pressure air nozzles Na1 and Na2. First, as shown in FIG. 1, the pipe axes P1, P2 of the pair of high-pressure air nozzles Na1, Na2 are aligned along the pipe axis P3 of the fuel gas nozzle Nb, and the pair of high-pressure air nozzles Na1, Na2 are arranged on either side of the fuel gas nozzle Nb. Here, the pair of high-pressure air nozzles Na1, Na2 sandwich the fuel gas nozzle Nb in such a manner that, as shown in FIG. 3, when viewed from the tip of the fuel gas nozzle Nb, the pipe axis P1 of one high-pressure air nozzle Na1, the pipe axis P2 of the other high-pressure air nozzle Na2, and the pipe axis P3 of the fuel gas nozzle Nb are aligned in a straight line.

[0032] Furthermore, the fuel gas injection holes Nbx that inject the fuel gas F from the fuel gas nozzle Nb are formed only on the side peripheral surface of the fuel gas nozzle Nb excluding the tip thereof, as shown in FIG. 1, and the high-pressure air injection holes Na1x, Na2x that inject high-pressure air from the high-pressure air nozzles Na1, Na2 are formed only on the side peripheral surface of the high-pressure air nozzles Na1, Na2 excluding the tip thereof, as shown in FIG. 3. To further explain, the multiple fuel gas injection holes Nbx (three in FIG. 1) are opened vertically upward (toward the arrow Z) as shown in FIG. 1, and the high-pressure air injection holes Na1x, Na2x are each provided facing between the direction toward the fuel gas nozzle Nb and the vertically upward direction (the direction along the arrow Z) as shown in FIG. 3.

[0033] The high-pressure air injection holes Na1x, Na2x are formed in the shape of slits along the circumferential direction of the side peripheral surfaces of the high-pressure air nozzles Na1, Na2. Furthermore, as shown in Fig. 3, when viewed in the direction along the pipe axis P2 of the fuel gas nozzle Nb, the angle α1 formed by a line connecting the pipe axis P1 of one high-pressure air nozzle Na1 to the slit center position of the high-pressure air injection hole Na1x formed in that one high-pressure air nozzle Na1 and a line connecting the pipe axis P1 of one high-pressure air nozzle Na1 to the pipe axis P2 of the fuel gas nozzle Nb is set to be equal to or greater than 0° and equal to 45°, more preferably set to be 30°. Similarly, the angle α2 formed by a line connecting the pipe axis P2 of the other high-pressure air nozzle Na2 to the slit center position of the high-pressure air injection hole Na2x formed in that other high-pressure air nozzle Na2 and a line connecting the pipe axis P2 of the other high-pressure air nozzle Na2 to the pipe axis P3 of the fuel gas nozzle Nb is set to be equal to or greater than 0° and equal to 45°, more preferably set to be 30°. Thus, it is preferable that the angle α1 and the angle α2 are equal.

[0034] Incidentally, the inventors of the present invention have experimentally confirmed that good combustion results can be obtained when the slit width of the high-pressure air injection holes Na1x and Na2x is 1 mm, the hole diameter of the fuel gas injection holes Nbx of the fuel gas nozzle Nb is 5.2 mm, the number of holes is 5, and city gas 13A is used as the fuel gas. The slit width of the high-pressure air injection holes Na1x and Na2x, and the hole diameter and number of the fuel gas injection holes Nbx of the fuel gas nozzle Nb are not limited to the above values.

[0035] In the above configuration, when the fuel gas nozzle Nbx and the high-pressure air nozzle Na are located relatively close to each other in the direction along the pipe axis P3 of the fuel gas nozzle Nb, the flow of fuel gas F and the flow of high-pressure air Ah are formed along each other's flows without colliding with each other, so that the high-pressure air Ah injected from the paired high-pressure air nozzles Na1, Na2 draws in the fuel gas F injected from the fuel gas nozzle Nb, thereby forming paired flames FL in alternating combustion.

[0036] Incidentally, as described above, the fuel gas injection holes Nbx for injecting the fuel gas F from the fuel gas nozzle Nb are formed only on the side peripheral surface excluding the tip of the fuel gas nozzle Nb, as shown in FIG. 1, and the high-pressure air injection holes Na1x, Na2x for injecting the high-pressure air from the high-pressure air nozzles Na1, Na2 are formed only on the side peripheral surface excluding the tip of the high-pressure air nozzles Na1, Na2, as shown in FIG. 3. Therefore, even if the regenerative burner 100 is installed with respect to the metal melting furnace 200 in a state in which the tube axis P3 of the fuel gas nozzle Nb intersects with the outer peripheral wall 210b of the crucible 210, as shown in FIG. 1, the formed flame FL is less likely to collide with a local portion 210a on the outer periphery of the crucible 210 of the metal melting furnace 200, and damage to the crucible 210 can be effectively suppressed.

[0037] 2(a), the regenerative burner 100 according to this embodiment is provided with a high-pressure air injection direction adjustment mechanism R that adjusts the injection direction of high-pressure air Ah from the high-pressure air injection orifices Na1x by rotating and fixing the high-pressure air nozzle Na1 about the pipe axis P1, and a fixing screw R1 that rotatably fixes the high-pressure air nozzle Na1 to the base end K1 of the high-pressure air pipe L1. Also, the high-pressure air nozzle Na2 is provided with a high-pressure air injection direction adjustment mechanism R that adjusts the injection direction of high-pressure air Ah from the high-pressure air injection orifices Na2x by rotating and fixing the high-pressure air nozzle Na2 about the pipe axis P2, and a fixing screw R2 that rotatably fixes the high-pressure air nozzle Na2 to the base end K2 of the high-pressure air pipe L2. This allows the angles α1 and α2 to be freely adjusted.

[0038] 1, the fuel gas injection holes Nbx for injecting fuel gas F from the fuel gas nozzle Nb and the high-pressure air injection holes Na1x, Na2x for injecting high-pressure air Ah from the high-pressure air nozzles Na1, Na2 are provided at different positions in the axial direction along the axial axis P3 of the fuel gas nozzle Nb. This effectively prevents the high-pressure air Ah from being injected near the fuel gas injection holes Nbx during alternating combustion, causing the flame to go out due to the influence of the high-pressure air Ah. Incidentally, in this embodiment, the fuel gas injection holes Nbx are provided closer to the base end than the high-pressure air injection holes Na1x, Na2x in the axial direction along the axial axis P3 of the fuel gas nozzle Nb.

[0039] Furthermore, in the regenerative burner 100 according to this embodiment, as shown in Figures 1 and 3, the injection direction of the fuel gas F from the fuel gas injection holes Nbx that inject the fuel gas F from the fuel gas nozzle Nb is set vertically upward, and in this configuration, an ultraviolet sensor Suv is provided as a flame detection means for detecting the flame FL that is engulfed below the fuel gas nozzle Nb. The inventors have confirmed that this configuration can achieve stable detection of flame FL.

[0040] Incidentally, in a hot state in which alternating combustion is being performed, the total head pressure of the pilot fuel Fp and the main fuel Fm is 3.6 kPaG, the head pressure of the pilot air Ap is 0.15 kPaG, and the pressure of the high-pressure air Ah entering the high-pressure air nozzle Na is set to approximately 60 kPaG or more and 68 kPaG or less.

[0041] [Another embodiment] (1) In the above embodiment, the regenerative burner 100 is shown as an example of a configuration in which it is provided in a metal melting furnace 200, but it can be provided in any furnace as long as it is capable of being provided with a paired regenerative heat storage body T.

[0042] (2) In the metal melting furnace 200 according to the above embodiment, a configuration including one regenerative burner 100 and a paired heat storage body T is shown, but a configuration including multiple regenerative burners 100 and a paired heat storage body T for each regenerative burner 100 may also be shown.

[0043] (3) In the above embodiment, a configuration example in which one pair of high-pressure air nozzles Na1 and Na2 is provided has been shown, but a configuration in which a plurality of such nozzles are provided may also be used.

[0044] (4) In the above embodiment, as an example of a configuration in which the pair of high-pressure air nozzles Na1 and Na2 sandwich the fuel gas nozzle Nb, as shown in FIG. 3, when viewed from the tip side of the fuel gas nozzle Nb, the pipe axis P1 of one high-pressure air nozzle Na1, the pipe axis P2 of the other high-pressure air nozzle Na1, and the pipe axis P3 of the fuel gas nozzle Nb are aligned in a straight line. The manner in which the pair of high-pressure air nozzles Na1 and Na2 sandwich the fuel gas nozzle Nb is not limited to the above configuration, and for example, a configuration can be adopted in which the fuel gas nozzle Nb is disposed at various positions that are appropriately changed so as to be equidistant from both the pipe axis P1 of one high-pressure air nozzle Na1 and the pipe axis P2 of the other high-pressure air nozzle Na1 when viewed from the tip side of the fuel gas nozzle Nb.

[0045] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0046] The regenerative burner of the present invention and a metal melting furnace equipped with the same can be effectively used as a regenerative burner and a metal melting furnace equipped with the same, which can maintain high combustion efficiency while simplifying the overall burner configuration and also simplifying the configuration related to flame detection. [Explanation of symbols]

[0047] 100: Regenerative Burner 200: Metal melting furnace 200a: Furnace wall Ah: High pressure air E: Combustion exhaust gas F: Fuel gas FL:Flame Na: High pressure air nozzle Na1x, Na2x: High-pressure air injection holes Nb: Fuel gas nozzle Nbx: Fuel gas injection hole P1: High pressure air nozzle pipe axis P2: High pressure air nozzle pipe axis P3: Fuel gas nozzle tube axis R: High-pressure air injection direction adjustment mechanism S: Control device Sp1: First pressure sensor Sp2: Second pressure sensor SUV: Ultraviolet sensor T: Heat storage body

Claims

1. A regenerative burner that includes a pair of heat storage bodies, and is capable of forming a flame by alternately controlling combustion air and fuel gas heated in the first flow state or the second flow state by switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other of the heat storage bodies, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other of the heat storage bodies, The combustion chamber includes only a single fuel gas nozzle provided at the tip of the fuel gas pipe as a nozzle for injecting fuel gas into the combustion space, a pair of high-pressure air nozzles for injecting high-pressure air having a pressure higher than atmospheric pressure into the combustion space in different directions from each other, a direction in which the high-pressure air is sprayed from the pair of high-pressure air nozzles is set in a direction in which the fuel gas sprayed from the fuel gas nozzle can be drawn into the flow of high-pressure air; a control device that executes the alternating combustion control by injecting high-pressure air from one of the high-pressure air nozzles and stopping the injection of high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the first flow state, and by stopping the injection of high-pressure air from one of the high-pressure air nozzles and injecting high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the second flow state, a pipe axis of the pair of high-pressure air nozzles is aligned with a pipe axis of the fuel gas nozzle, and the pair of high-pressure air nozzles are provided so as to sandwich the fuel gas nozzle; a fuel gas injection hole for injecting fuel gas from the fuel gas nozzle is formed only on a side circumferential surface of the fuel gas nozzle excluding a tip end thereof, A regenerative burner in which high-pressure air injection holes for injecting high-pressure air from the high-pressure air nozzle are formed only on the side peripheral surface of the high-pressure air nozzle excluding the tip thereof.

2. A regenerative burner that has a pair of heat storage bodies, and is capable of switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other heat storage body, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other heat storage body, and performing alternating combustion control of the combustion air and fuel gas heated in the first flow state or the second flow state to form a flame, The combustion chamber includes only a single fuel gas nozzle provided at the tip of the fuel gas pipe as a nozzle for injecting fuel gas into the combustion space, a pair of high-pressure air nozzles for injecting high-pressure air having a pressure higher than atmospheric pressure into the combustion space in different directions from each other, a direction in which the high-pressure air is sprayed from the pair of high-pressure air nozzles is set in a direction in which the fuel gas sprayed from the fuel gas nozzle can be drawn into the flow of high-pressure air; a control device that executes the alternating combustion control by injecting high-pressure air from one of the high-pressure air nozzles and stopping the injection of high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the first flow state, and by stopping the injection of high-pressure air from one of the high-pressure air nozzles and injecting high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the second flow state, a pipe axis of the pair of high-pressure air nozzles is aligned with a pipe axis of the fuel gas nozzle, and the pair of high-pressure air nozzles are provided so as to sandwich the fuel gas nozzle; A regenerative burner in which a fuel gas injection hole for injecting fuel gas from the fuel gas nozzle and a high-pressure air injection hole for injecting high-pressure air from the high-pressure air nozzle are provided at different positions in a pipe axis direction along the pipe axis of the fuel gas nozzle.

3. A regenerative burner as described in claim 1 or 2, in which each of the paired high-pressure air nozzles is provided with a high-pressure air injection direction adjustment mechanism that can adjust the injection direction of high-pressure air from the high-pressure air injection hole by rotating and fixing the high-pressure air nozzle around the pipe axis.

4. The injection direction of the fuel gas from the fuel gas injection hole that injects the fuel gas from the fuel gas nozzle is set vertically upward, 4. The regenerative burner according to claim 1, further comprising a flame detection means for detecting a flame engulfed below the fuel gas nozzle.

5. A regenerative burner that has a pair of heat storage bodies, and is capable of switching between a first flow state in which combustion exhaust gas flows through one of the heat storage bodies and combustion air flows through the other heat storage body, and a second flow state in which combustion air flows through one of the heat storage bodies and combustion exhaust gas flows through the other heat storage body, and performing alternating combustion control of the combustion air and fuel gas heated in the first flow state or the second flow state to form a flame, The combustion chamber includes only a single fuel gas nozzle provided at the tip of the fuel gas pipe as a nozzle for injecting fuel gas into the combustion space, a pair of high-pressure air nozzles for injecting high-pressure air having a pressure higher than atmospheric pressure into the combustion space in different directions from each other, a direction in which the high-pressure air is sprayed from the pair of high-pressure air nozzles is set in a direction in which the fuel gas sprayed from the fuel gas nozzle can be drawn into the flow of high-pressure air; a control device that executes the alternating combustion control by injecting high-pressure air from one of the high-pressure air nozzles and stopping the injection of high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the first flow state, and by stopping the injection of high-pressure air from one of the high-pressure air nozzles and injecting high-pressure air from the other high-pressure air nozzle while injecting fuel gas from the fuel gas nozzle in the second flow state, the high-pressure air nozzle is made of ceramic containing alumina as a main component; a pressure detection means for detecting the pressure inside the high-pressure air nozzle; When the pressure detected by the pressure detection means falls below a predetermined lower limit pressure of high-pressure air, the control device determines that damage to the high-pressure air nozzle has occurred and executes an alternating combustion stop process to stop the alternating combustion control.

6. A metal melting furnace in which a regenerative burner described in any one of claims 1 to 5 is installed through the furnace wall of a cylindrical furnace, and a pot or crucible is placed inside the cylindrical furnace, and a flame is formed along the inner surface of the furnace wall by the alternating combustion control.

7. A metal melting furnace as described in Claim 6, in which a pair of heat storage bodies are arranged on either side of the regenerative burner.

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