Regenerative burner

Abstract

To provide a heat storage type burner forming a short flame length by direct fire combustion, a long flame length by normal diffusion combustion, and an intermediate flame length.SOLUTION: A heat storage type burner includes: air supplying / exhausting parts 11a, 11b which supply combustion-supporting gas and discharge exhaust gas via heat reservoirs 12a, 12b disposed inside; first nozzles 21a, 21b disposed inside the air supplying / exhausting parts 11a, 11b and discharging fuel; second nozzles 22a, 22b which are separately arranged from the air supplying / exhausting parts 11a, 11b and discharge fuel along a flow direction of the combustion-supporting gas to be supplied by the air supplying / exhausting parts 11a, 11b; and third nozzles 23a, 23b which are disposed between the air supplying / exhausting parts 11a, 11b and the second nozzles 22a, 22b, and discharge fuel to the combustion-supporting gas supplied by the air supplying / exhausting parts 11a, 11b.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a regenerative burner. [Background technology]

[0002] Conventionally, a pair of regenerative burners alternately supply oxidizing gas and discharge exhaust gas, recovering the heat of the exhaust gas and using it to preheat the oxidizing gas, thereby achieving high thermal efficiency.

[0003] Patent Document 1 discloses a burner that makes it possible to change the flame length by changing the flow rate ratio between the inner and outer flows of fuel gas. Patent Documents 2 and 3 disclose a regenerative burner that, when a furnace is started up or when the temperature inside the furnace is below the ignition temperature, ejects pre-mixed air and fuel from a central nozzle to create a straight flame, and when the atmosphere inside the furnace rises above the ignition temperature of the fuel, diffuses and burns the fuel ejected directly into the furnace.

[0004] Patent Document 4 discloses a regenerative burner device that arranges a pair of auxiliary fuel pipes, an intake and exhaust section, and a main fuel pipe side by side, and adjusts the flame length and temperature distribution within the furnace by shifting the combustion timing of the auxiliary fuel pipes and the combustion timing of the main fuel pipes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 60-11018 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-74834 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-232475 [Patent Document 4] Patent No. 6448679 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, regenerative burners have selectively used direct combustion, which has a short flame length, and diffusion combustion, which has a long flame length, and adjusted the combustion volume of each to adjust the flame length and thereby the temperature distribution within the furnace. However, in diffusion combustion, even if an attempt is made to shorten the flame length by reducing the combustion volume, in order to maintain stable diffusion combustion, the flame length can only be shortened to, for example, approximately 30% of the normal flame length in diffusion combustion. Furthermore, in direct combustion, even if an attempt is made to maximize the flame length by maximizing the combustion volume, the flame length can only be extended to approximately 20% of the normal flame length in diffusion combustion. Increasing the direct combustion nozzle would increase the flame length in direct combustion, but the high-temperature flame would increase nitrogen oxide (NOx) emissions. Therefore, in conventional regenerative burners, there is a gap in the flame length between the flame length in normal diffusion combustion and the flame length in direct combustion.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a regenerative burner that produces a flame length intermediate between the short flame length produced by direct combustion and the long flame length produced by ordinary diffusion combustion. [Means for solving the problem]

[0008] In order to solve the above problems, a regenerative burner according to one aspect of the present invention comprises: an intake / exhaust section that supplies combustion-supporting gas and exhausts exhaust gas through a heat storage body disposed inside; a first nozzle disposed inside the intake and exhaust unit and configured to discharge fuel; a second nozzle disposed apart from the intake and exhaust unit and configured to discharge fuel along a flow direction of the combustion-supporting gas supplied from the intake and exhaust unit; The combustion control system is characterized by comprising a third nozzle disposed between the intake and exhaust unit and the second nozzle, for discharging the fuel into the combustion-supporting gas supplied from the intake and exhaust unit. [Effects of the Invention]

[0009] According to this invention, a novel diffusion combustion method using a third nozzle can be used to form a flame length intermediate between the short flame length produced by direct combustion using the first nozzle and the long flame length produced by normal diffusion combustion using the second nozzle, thereby making it possible to adjust the temperature distribution within the furnace while suppressing nitrogen oxide (NOx) emissions without enlarging the size of the first nozzle. [Brief explanation of the drawings]

[0010] [Figure 1] 1A and 1B are diagrams illustrating direct-flame combustion using the intake and exhaust sections of a regenerative burner. (A) shows direct-flame combustion using one first nozzle, and (B) shows direct-flame combustion using the other first nozzle. [Figure 2] 1 is a diagram illustrating typical diffusion combustion in a regenerative burner. (A) shows typical diffusion combustion using one secondary nozzle, and (B) shows typical diffusion combustion using the other secondary nozzle. [Figure 3] 1A and 1B are diagrams illustrating a regenerative burner according to a first embodiment, in which (A) shows a new diffusion combustion using one third nozzle, and (B) shows a new diffusion combustion using the other third nozzle. [Figure 4] 10A and 10B are diagrams illustrating a regenerative burner according to a second embodiment, in which (A) shows a new diffusion combustion using one third nozzle, and (B) shows a new diffusion combustion using the other third nozzle. [Figure 5] 1 is a diagram illustrating the characteristics of the regenerative burner of the present invention. (A) shows the maximum flame length during direct flame combustion using the first nozzle, (B) shows the maximum flame length during normal diffusion combustion using the second nozzle, (C) shows the minimum flame length during normal diffusion combustion using the second nozzle, and (D) shows the flame length during the novel diffusion combustion using the third nozzle. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of regenerative burners 10a, 10b according to the present invention will be described with reference to the drawings. For convenience, in Fig. 1 and other figures, the left side is referred to as one side and the right side is referred to as the other side across the center of the width of the furnace 1. In Fig. 1 and other figures, the open state of the valve is indicated by an outline, and the closed state of the valve is indicated by a solid black.

[0012] [First embodiment] The regenerative burners 10a and 10b according to the first embodiment will be described with reference to FIGS. 1 to 3 and 5. FIG. 1 is a diagram illustrating direct-flame combustion using the intake and exhaust sections 11a and 11b in the regenerative burners 10a and 10b. (A) shows direct-flame combustion using one first nozzle 21a, and (B) shows direct-flame combustion using the other first nozzle 21b. FIG. 2 is a diagram illustrating normal diffusion combustion in the regenerative burners 10a and 10b. (A) shows normal diffusion combustion using one second nozzle 22a, and (B) shows normal diffusion combustion using the other second nozzle 22b. FIG. 3 is a diagram illustrating the regenerative burners 10a and 10b according to the first embodiment. (A) shows novel diffusion combustion using one third nozzle 23a, and (B) shows novel diffusion combustion using the other third nozzle 23b. 5 is a diagram illustrating the characteristics of the regenerative burners 10a and 10b of the present invention. (A) shows the maximum flame length L1 during direct combustion using the first nozzles 21a and 21b, (B) shows the maximum flame length L2-1 during normal diffusion combustion using the second nozzles 22a and 22b, (C) shows the minimum flame length L2-2 during normal diffusion combustion using the second nozzles 22a and 22b, and (D) shows the flame length L3 during the novel diffusion combustion using the third nozzles 23a and 23b.

[0013] As shown in FIG. 1, for example, a pair of regenerative burners 10a, 10b are arranged facing each other on the furnace wall 2 of the furnace 1. One regenerative burner 10a has an air intake and exhaust section 11a with an air intake and exhaust port 14a, a first nozzle 21a, a second nozzle 22a, and a third nozzle 23a. For example, one of the pair of second nozzles 22a, 22a is spaced apart to sandwich the air intake and exhaust section 11a, and one of the pair of third nozzles 23a, 23a is arranged between the one of the air intake and exhaust section 11a and the one of the second nozzles 22a. The one of the air intake and exhaust port 14a, the outlet of the one of the second nozzles 22a, and the outlet of the one of the third nozzles 23a are arranged flush with the wall surface 2 located on one side, for example.

[0014] The other regenerative burner 10b also has a second intake and exhaust section 11b with a second intake and exhaust port 14b, a first nozzle 21b, a second nozzle 22b, and a third nozzle 23b. For example, the pair of second nozzles 22b, 22b are spaced apart to sandwich the other intake and exhaust section 11b, and the pair of third nozzles 23b, 23b are disposed between the other intake and exhaust section 11b and the second nozzle 22b. The other intake and exhaust port 14b, the outlet of the second nozzle 22b, and the outlet of the third nozzle 23b are disposed flush with the wall surface 2 located on the other side, for example.

[0015] In one supply / exhaust section 11a, one heat storage body 12a is disposed therein, and one first nozzle 21a is disposed on the side closer to the furnace interior 3 than the one heat storage body 12a. In the other supply / exhaust section 11b, the other heat storage body 12b is disposed therein, and the other first nozzle 21b is disposed on the side closer to the furnace interior 3 than the other heat storage body 12b.

[0016] Each of the first nozzle 21a, the second nozzle 22a, and the third nozzle 23a is connected to a fuel supply pipe 41 that supplies fuel. A first valve 31a corresponding to the first nozzle 21a, a second valve 32a corresponding to the second nozzle 22a, and a third valve 33a corresponding to the third nozzle 23a are disposed in the fuel supply pipe 41. The first valve 31a, the second valve 32a, and the third valve 33a adjust the amount of fuel supplied from the fuel supply pipe 41, respectively.

[0017] Similarly, the other first nozzle 21b, the other second nozzle 22b, and the other third nozzle 23b are each connected to a fuel supply pipe 41 that supplies fuel. The fuel supply pipe 41 is provided with the other first valve 31b corresponding to the other first nozzle 21b, the other second valve 32b corresponding to the other second nozzle 22b, and the other third valve 33b corresponding to the other third nozzle 23b. The first valve 31b, the second valve 32b, and the third valve 33b each adjust the amount of fuel supplied from the fuel supply pipe 41. For example, a fuel gas such as natural gas (city gas), propane, butane, hydrogen, or ammonia is used as the fuel.

[0018] One second nozzle 22a and the other second nozzle 22b are configured to discharge fuel along the flow direction of the combustion-supporting gas discharged from one intake and exhaust section 11a and the other intake and exhaust section 11b, respectively.

[0019] One third nozzle 23a and the other third nozzle 23b are configured to discharge fuel obliquely toward the flow of the oxidizing gas discharged from one intake and exhaust section 11a and the other intake and exhaust section 11b, respectively. As a result, the discharged fuel diffuses in the furnace interior 3 over a narrower range than in normal diffusion combustion and burns in a well-mixed state, so that a flame due to new diffusion combustion (shown as F3 in FIG. 5(D)) is formed over a narrow range, and the flame length due to new diffusion combustion (shown as L3 in FIG. 5(D)) is shorter than the flame length due to normal diffusion combustion.

[0020] An oxidizing gas supply pipe 45 and an exhaust gas discharge pipe 46 are connected to one intake and exhaust section 11a and the other intake and exhaust section 11b. One oxidizing gas valve 35a corresponding to one intake and exhaust section 11a and the other oxidizing gas valve 35b corresponding to the other intake and exhaust section 11b are disposed in the oxidizing gas supply pipe 45. An air supply fan 51 is disposed upstream of the oxidizing gas supply pipe 45, and the oxidizing gas is supplied to the intake and exhaust sections 11a and 11b through the oxidizing gas supply pipe 45. As the oxidizing gas, for example, air is used, but oxygen alone or a mixed gas containing oxygen can also be used.

[0021] An exhaust fan 53 and a chimney 55 are disposed downstream of exhaust gas exhaust pipe 46, and the exhaust gas flows through exhaust gas exhaust pipe 46 and is then discharged from chimney 55. Exhaust gas exhaust pipe 46 is provided with one exhaust gas valve 36a corresponding to one intake and exhaust section 11a, and the other exhaust gas valve 36b corresponding to the other intake and exhaust section 11b.

[0022] Next, the operation of the pair of regenerative burners 10a, 10b configured as described above will be described.

[0023] Although not shown, when the furnace 1 starts operating, both regenerative burners 10a and 10b are used simultaneously to perform combustion using fuel discharged from the first nozzles 21a and 21b and oxidizing gas supplied from the oxidizing gas supply pipe 45, thereby raising the temperature inside the furnace 3. Exhaust gas generated by the combustion is discharged through an exhaust port (not shown) provided in the furnace wall 2.

[0024] When the temperature inside the furnace 3 reaches or exceeds the ignition temperature of the fuel (e.g., 800°C), the system switches to regenerative combustion, in which the operation of one regenerative burner 10a and the operation of the other regenerative burner 10b alternate. That is, in regenerative combustion, one regenerative burner 10a performs combustion while the other regenerative burner 10b performs heat storage to store the heat of the exhaust gas, and one regenerative burner 10a performs heat storage to store the heat of the exhaust gas while the other regenerative burner 10b performs combustion, alternately. As will be explained below, in regenerative combustion, diffusion combustion using the second nozzles 22a, 22b is usually performed (for simplicity, this will be referred to as "normal diffusion combustion").

[0025] With reference to FIG. 2, normal diffusion combustion in one regenerative burner 10a and the other regenerative burner 10b will be described.

[0026] 2(A), opening one second valve 32a discharges fuel from one second nozzle 22a, and the discharged fuel diffuses over a wide area within the furnace 3. The fuel that has diffused within the furnace 3 encounters the oxidizing gas supplied from one intake and exhaust section 11a by opening one oxidizing gas valve 35a, and the regenerative burner 10a performs normal diffusion combustion. Therefore, one second nozzle 22a causes normal diffusion combustion at a position away from one intake and exhaust section 11a.

[0027] 2(B), by opening the other second valve 32b, fuel is discharged from the other second nozzle 22b, and the discharged fuel diffuses over a wide area within the furnace 3. By opening the other combustion-supporting gas valve 35b, the fuel that has diffused within the furnace 3 encounters the combustion-supporting gas supplied from the other intake and exhaust section 11b, and the other regenerative burner 10b performs normal diffusion combustion. Therefore, the other second nozzle 22b causes normal diffusion combustion at a position away from the other intake and exhaust section 11b.

[0028] In normal diffusion combustion, the temperature inside the furnace 3 is equal to or higher than the ignition temperature of the fuel, so the fuel discharged from the second nozzles 22a, 22b spontaneously combusts when it encounters the oxidizing gas supplied from the intake and exhaust sections 11a, 11b.

[0029] Therefore, in normal diffusion combustion using the second nozzles 22a and 22b, the fuel supplied to the furnace interior 3 burns while diffusing over a wide range within the furnace interior 3, forming a second flame F2 by diffusion combustion in various locations within the furnace interior 3. The second flame F2 shown in FIG. 2 is also formed in areas that cannot be reached by the first flame F1 by direct combustion shown in FIG. 1, and heats the workpiece (not shown) in the furnace interior 3. Therefore, heating by normal diffusion combustion can heat a wide range within the furnace interior 3. With normal diffusion combustion, the flame temperature is low, which can reduce nitrogen oxide (NOx) emissions.

[0030] As shown in Figure 2(A), while one regenerative burner 10a is performing normal diffusion combustion, the other regenerative burner 10b is performing heat storage operation, and as shown in Figure 2(B), while one regenerative burner 10a is performing heat storage operation, the other regenerative burner 10b is performing normal diffusion combustion.

[0031] The heat storage operation of the regenerative burners 10a and 10b will now be described. In the heat storage operation, the heat of the exhaust gas generated by combustion in the regenerative burners 10a and 10b is stored. For example, in FIG. 2(A), the exhaust gas generated by normal diffusion combustion in one regenerative burner 10a is taken into the other intake and exhaust section 11b when the other exhaust gas valve 36b in the other regenerative burner 10b is opened and the exhaust gas is sucked in by the exhaust fan 53. As the exhaust gas passes through the other intake and exhaust section 11b, the other regenerative heat storage body 12b disposed in the other intake and exhaust section 11b absorbs heat from the exhaust gas, thereby storing heat in the other regenerative heat storage body 12b. The heat stored in the other regenerative heat storage body 12b preheats the oxidizing gas when it passes through the other regenerative heat storage body 12b the next time the other regenerative burner 10b burns.

[0032] Similarly, in FIG. 2(B), exhaust gas generated by normal diffusion combustion in the other regenerative burner 10b is drawn into one of the intake and exhaust sections 11a by opening one of the exhaust gas valves 36a in one of the regenerative burners 10a and being sucked in by the exhaust fan 53. As the exhaust gas passes through one of the intake and exhaust sections 11a, one of the regenerative heat storage bodies 12a disposed in one of the intake and exhaust sections 11a absorbs heat from the exhaust gas, thereby storing heat in one of the regenerative heat storage bodies 12a. The heat stored in one of the regenerative heat storage bodies 12a preheats the oxidizing gas when it passes through one of the regenerative heat storage bodies 12a the next time the one of the regenerative burners 10a burns. The opening and closing operations of the various valves 31a, 31b, 32a, 32b, 33a, 33b, 35a, 35b, 36a, and 36b are controlled by a control unit (not shown).

[0033] Direct flame combustion is used when a flame length shorter than the minimum flame length (shown as L2-2 in FIG. 5(C)) required in regenerative combustion is required. Direct flame combustion in one regenerative burner 10a and the other regenerative burner 10b will be described with reference to FIG. 1.

[0034] 1(A), one first valve 31a and one combustion-supporting gas valve 35a are opened, and the other valves 31b, 32a, 32b, 33a, and 33b and the other combustion-supporting gas valve 35b are closed. This causes the fuel discharged from one first nozzle 21a to be premixed with the combustion-supporting gas supplied to one intake / exhaust section 11a. In premixed direct-flame combustion, one first flame F1 is generated, which has high combustion efficiency and linearity.

[0035] 1(B), the other first valve 31b and the other combustion-supporting gas valve 35b are opened, and the other valves 31a, 32a, 32b, 33a, and 33b and the one combustion-supporting gas valve 35a are closed. This causes the fuel discharged from the other first nozzle 21b to be premixed with the combustion-supporting gas supplied to the other intake / exhaust section 11b. In premixed direct-flame combustion, the other first flame F1 is formed, which has high combustion efficiency and linearity.

[0036] In regenerative combustion, when a gap in flame length between the minimum flame length in normal diffusion combustion (shown as L2-2 in FIG. 5(C)) and the maximum flame length in direct flame combustion (shown as L1 in FIG. 5(A)) is required, new diffusion combustion is performed. The new diffusion combustion in one regenerative burner 10a and the other regenerative burner 10b will be described with reference to FIG. 3.

[0037] In Fig. 3(A), opening one third valve 33a discharges fuel from one third nozzle 23a, and the discharged fuel diffuses within the furnace 3 over a narrower range than in the case of the above-described normal diffusion combustion. By opening one combustion-supporting gas valve 35a, the diffused fuel encounters the combustion-supporting gas supplied from one intake and exhaust section 11a, causing one regenerative burner 10a to form a new diffusion combustion flame (shown as F3 in Fig. 5(D)) over a narrow range. Therefore, one third nozzle 23a generates new diffusion combustion at a position closer to one intake and exhaust section 11a than in normal diffusion combustion, forming a flame length (shown as L3 in Fig. 5(D)) shorter than the flame length in normal diffusion combustion.

[0038] In Fig. 3(B), opening the other third valve 33b discharges fuel from the other third nozzle 23b, and the discharged fuel diffuses within the furnace 3 over a narrower range than in the case of normal diffusion combustion described above. By opening the other combustion-supporting gas valve 35b, the diffused fuel encounters the combustion-supporting gas supplied from the other intake and exhaust section 11b, causing the other regenerative burner 10b to form a new diffusion combustion flame (shown as F3 in Fig. 5(D)) over a narrower range. Therefore, the other third nozzle 23b generates new diffusion combustion, which forms a flame length (shown as L3 in Fig. 5(D)) shorter than that of normal diffusion combustion, at a position closer to the other intake and exhaust section 11b than in normal diffusion combustion.

[0039] Furthermore, in the new diffusion combustion, since the temperature inside the furnace 3 is equal to or higher than the ignition temperature of the fuel, the fuel discharged from the third nozzles 23a, 23b spontaneously combusts when it encounters the oxidizing gas supplied from the intake and exhaust sections 11a, 11b.

[0040] Therefore, in the novel diffusion combustion using the third nozzles 23a, 23b, the fuel supplied to the furnace interior 3 is burned in a well-mixed state while diffusing within the furnace interior 3 over a narrower range than in the case of normal diffusion combustion, and a third flame F3 is formed by the novel diffusion combustion at various points within the furnace interior 3. In the novel diffusion combustion, as in the case of normal diffusion combustion, the flame temperature is low, which makes it possible to suppress emissions of nitrogen oxides (NOx).

[0041] As in the case of normal diffusion combustion, as shown in Figure 3(A), while one regenerative burner 10a is performing a new diffusion combustion, the other regenerative burner 10b is performing a heat storage operation using the other regenerative body 12b, and the heat stored in the other regenerative body 12b preheats the oxidizing gas when it passes through the other regenerative body 12b the next time the other regenerative burner 10b burns. Also, as shown in Figure 3(B), while the other regenerative burner 10b is performing a new diffusion combustion, one regenerative burner 10a is performing a heat storage operation using the one regenerative body 12a, and the heat stored in the one regenerative body 12a preheats the oxidizing gas when it passes through the one regenerative body 12a the next time the other regenerative burner 10a burns.

[0042] The difference in flame length between the regenerative burners 10a and 10b of the present invention will be explained with reference to FIG.

[0043] As shown in Figure 5(A), the first flame F1 during direct combustion using the first nozzles 21a and 21b has a maximum flame length L1. As shown in Figure 5(B), the second flame F2 during normal diffusion combustion using the second nozzles 22a and 22b has a maximum flame length L2-1. As shown in Figure 5(C), the second flame F2 during normal diffusion combustion using the second nozzles 22a and 22b has a minimum flame length L2-2. As shown in Figure 5(D), the third flame F3 during novel diffusion combustion using the third nozzles 23a and 23b has a flame length L3.

[0044] In the first flame F1 generated by direct combustion shown in Figure 5(A), the flame length can be changed by adjusting the combustion amount, but the range of variation of the flame length is small, remaining at a maximum of L1. The second flame F2 generated by conventional diffusion combustion can vary the flame length more widely than the first flame F1 shown in Figure 5(A), and has a flame length range from the maximum flame length L2-1 shown in Figure 5(B) to the minimum flame length L2-2 shown in Figure 5(C). There is a gap in the flame length between the maximum flame length L1 of direct combustion shown in Figure 5(A) and the minimum flame length L2-2 of conventional diffusion combustion shown in Figure 5(C).

[0045] In the novel diffusion combustion, the discharged fuel diffuses within the furnace interior 3 over a narrower range than in the case of normal diffusion combustion and burns in a well-mixed state, resulting in a flame length L3 that is shorter than the flame length achieved by normal diffusion combustion. The flame length L3 of the third flame F3 achieved by the novel diffusion combustion is configured to include the minimum flame length L2-2 of the second flame F2 achieved by normal diffusion combustion. Furthermore, the flame length L3 is configured to include the maximum flame length L1 of the first flame F1 achieved by direct combustion. In other words, the adjustment range of the fuel flow rate achieved by the third valves 33a and 33b is configured so that the flame length L3 of the third flame F3 achieved by the third nozzles 23a and 23b includes the maximum flame length L1 of the first flame F1 achieved by the first nozzles 21a and 21b and the minimum flame length L2-2 of the second flame F2 achieved by the second nozzles 22a and 22b. Therefore, the third flame F3 by the new diffusion combustion forms an intermediate flame length L3 that fills the gap between the maximum flame length L1 of the first flame F1 by direct combustion and the minimum flame length L2-2 of the second flame F2 by normal diffusion combustion. As a result, the new diffusion combustion can fill the gap in flame length with the intermediate flame length L3 between the maximum flame length L1 by direct combustion and the minimum flame length L2-2 by normal diffusion combustion.

[0046] Therefore, the novel diffusion combustion using the third nozzles 23a, 23b can form a flame length L3 that is intermediate between the short flame length resulting from direct flame combustion using the first nozzles 21a, 21b and the long flame length resulting from normal diffusion combustion using the second nozzles 22a, 22b, and can adjust the temperature distribution within the furnace while suppressing emissions of nitrogen oxides (NOx) without enlarging the size of the first nozzles 21a, 21b.

[0047] Second Embodiment The regenerative burners 10a and 10b according to the second embodiment will be described with reference to Figure 4. Figure 4(A) is a cross-sectional view of the regenerative burners 10a and 10b according to the second embodiment, schematically illustrating new diffusion combustion using one third nozzle 23a. Figure 4(B) is a cross-sectional view of the regenerative burners 10a and 10b according to the second embodiment, schematically illustrating new diffusion combustion using the other third nozzle 23b.

[0048] 4, one third nozzle 23a and the other third nozzle 23b are located near one intake and exhaust section 11a and the other intake and exhaust section 11b, respectively. At the same time, one third nozzle 23a and the other third nozzle 23b are configured to discharge fuel along the flow direction of the combustion-supporting gas discharged from one intake and exhaust section 11a and the other intake and exhaust section 11b, respectively.

[0049] In Figure 4(A), by opening one third valve 33a, the fuel discharged from one third nozzle 23a flows in the direction of the oxidizing gas, and the discharged fuel diffuses within the furnace 3 over a narrower area than in the case of the normal diffusion combustion described above. By opening one oxidizing gas valve 35a, the diffused fuel encounters the oxidizing gas supplied from one intake and exhaust section 11a, and one regenerative burner 10a performs new diffusion combustion. Therefore, one third nozzle 23a generates new diffusion combustion at a position closer to one intake and exhaust section 11a than in the case of normal diffusion combustion.

[0050] In Figure 4(B), by opening the other third valve 33b, the fuel discharged from the other third nozzle 23b flows in the direction of the oxidizing gas, and the discharged fuel diffuses within the furnace 3 over a narrower area than in the case of the normal diffusion combustion described above. By opening the other oxidizing gas valve 35b, the diffused fuel encounters the oxidizing gas supplied from the other intake and exhaust section 11b, and the other regenerative burner 10b performs new diffusion combustion. Therefore, the other third nozzle 23b generates new diffusion combustion at a position closer to the other intake and exhaust section 11b than in the case of normal diffusion combustion.

[0051] As in the first embodiment described above, since the temperature inside the furnace 3 is equal to or higher than the ignition temperature of the fuel, the fuel discharged from the third nozzles 23a, 23b spontaneously combusts when it encounters the oxidizing gas supplied from the intake and exhaust sections 11a, 11b.

[0052] In the novel diffusion combustion according to the second embodiment, the fuel supplied to the furnace interior 3 diffuses within the furnace interior 3 over a narrower range than in conventional diffusion combustion, burning with good mixing characteristics. This results in the formation of a third flame F3 at various locations within the furnace interior 3. Therefore, the novel diffusion combustion using the third nozzles 23a and 23b allows the formation of a flame length L3 intermediate between the short flame length achieved by direct combustion using the first nozzles 21a and 21b and the long flame length achieved by conventional diffusion combustion using the second nozzles 22a and 22b. This allows the temperature distribution within the furnace to be adjusted while suppressing nitrogen oxide (NOx) emissions without increasing the size of the first nozzles 21a and 21b. Furthermore, compared to the first embodiment (shown in FIG. 3 ), in which the fuel is discharged obliquely with respect to the flow direction of the oxidizing gas, the fuel diffuses farther, resulting in a flame length longer than that shown in FIG. 3 . This allows the flame length adjustment range to be shifted to the longer side, expanding the range of application.

[0053] Although specific embodiments and numerical values ​​of the present invention have been described, the present invention is not limited to the above-described embodiments and can be practiced with various modifications within the scope of the present invention.

[0054] In the above embodiment, one of the first valves 31a, 31b, the second valves 32a, 32b, and the third valves 33a, 33b, which function as on-off valves, is opened (while the remaining valves are closed) to perform one of direct flame combustion, normal diffusion combustion, and novel diffusion combustion. However, the first valves 31a, 31b, the second valves 32a, 32b, and the third valves 33a, 33b can each be an adjustment valve whose valve opening is adjustable to change the ratio of the discharge flow rate from the first nozzles 21a, 21b, the discharge flow rate from the second nozzles 22a, 22b, and the discharge flow rate from the third nozzles 23a, 23b. This allows the third flame F3 generated by novel diffusion combustion to form an appropriate intermediate flame length L3 between the maximum flame length L1 generated by direct flame combustion and the minimum flame length L2-2 generated by normal diffusion combustion. This allows the formation of an intermediate flame length L3 through a new diffusion combustion method using the third nozzles 23a, 23b, and the temperature distribution within the furnace can be adjusted while suppressing emissions of nitrogen oxides (NOx) without enlarging the size of the first nozzles 21a, 21b.

[0055] In the novel diffusion combustion described above, only the third valve 33a or 33b is opened to perform novel diffusion combustion using the third nozzle 23a or 23b. However, it is also possible to open both the first valve 31a or 31b and the third valve 33a or 33b and discharge fuel from the first nozzle 21a or 21b and the third nozzle 23a or 23b. This creates a novel combustion that combines novel diffusion combustion and direct combustion, forming a flame that is hotter than the novel diffusion combustion described above. Note that the fuel discharge from the first nozzles 21a and 21b and the third nozzles 23a and 23b can be performed simultaneously or with a slight delay.

[0056] In the above embodiment, the regenerative burners 10a, 10b are provided with the intake and exhaust sections 11a, 11b, the first nozzles 21a, 21b, the second nozzles 22a, 22b, and the third nozzles 23a, 23b. However, existing regenerative burners 10a, 10b equipped with the intake and exhaust sections 11a, 11b, the first nozzles 21a, 21b, and the second nozzles 22a, 22b can also be retrofitted with a new diffusion combustion system including the third nozzles 23a, 23b. This allows the above-described new diffusion combustion system to be easily added to existing regenerative burners 10a, 10b.

[0057] The present invention and its embodiments can be summarized as follows.

[0058] The regenerative burners 10a and 10b according to one embodiment of the present invention are: Intake and exhaust sections 11a and 11b supply combustion-supporting gas and exhaust exhaust gas through heat storage bodies 12a and 12b disposed therein; First nozzles 21a, 21b are disposed inside the intake and exhaust sections 11a, 11b and discharge fuel; second nozzles 22a, 22b that are disposed apart from the intake and exhaust sections 11a, 11b and discharge the fuel along the flow direction of the combustion-supporting gas supplied from the intake and exhaust sections 11a, 11b; and third nozzles 23a, 23b, which are arranged between the intake and exhaust sections 11a, 11b and the second nozzles 22a, 22b and which discharge the fuel into the combustion-supporting gas supplied from the intake and exhaust sections 11a, 11b.

[0059] According to the above configuration, a new diffusion combustion method using the third nozzles 23a, 23b can be used to form a flame length L3 that is intermediate between the short flame length achieved by direct flame combustion using the first nozzles 21a, 21b and the long flame length achieved by normal diffusion combustion using the second nozzles 22a, 22b, and the temperature distribution within the furnace can be adjusted while suppressing emissions of nitrogen oxides (NOx) without enlarging the size of the first nozzles 21a, 21b.

[0060] In addition, in one embodiment of the regenerative burners 10a and 10b, The third nozzles 23a and 23b are configured to inject the fuel obliquely toward the flow of the combustion-supporting gas.

[0061] According to the above embodiment, the discharged fuel diffuses within the furnace 3 over a narrower range than normal diffusion combustion and burns in a well-mixed state, so the flame due to the new diffusion combustion is formed over a narrow range, and the flame length L3 due to the new diffusion combustion is shorter than the flame length due to normal diffusion combustion.

[0062] In addition, in one embodiment of the regenerative burners 10a and 10b, A fuel supply pipe 41 that supplies fuel to the first nozzles 21a, 21b, the second nozzles 22a, 22b, and the third nozzles 23a, 23b is provided with first valves 31a, 31b, second valves 32a, 32b, and third valves 33a, 33b that adjust the amount of fuel supplied to each nozzle, so that the flame length L3 of the third flame F3 generated by the third nozzles 23a, 23b can be adjusted to include the maximum flame length L1 of the first flame F1 generated by the first nozzles 21a, 21b and the minimum flame length L2-2 of the second flame F2 generated by the second nozzles 22a, 22b.

[0063] According to the above embodiment, the blank flame length can be filled with a flame length L3 intermediate between the maximum flame length L1 due to direct combustion and the minimum flame length L2-2 due to normal diffusion combustion.

[0064] In addition, in one embodiment of the regenerative burners 10a and 10b, The fuel is discharged from the first nozzles 21a, 21b and the third nozzles 23a, 23b.

[0065] According to the above embodiment, by ejecting fuel from the first nozzle 21a or 21b and the third nozzle 23a or 23b together, a further new combustion is formed that mixes the new diffusion combustion and the direct flame combustion, and a flame with a higher temperature than the above-mentioned new diffusion combustion can be formed.

[0066] In another aspect, a method for modifying the regenerative burners 10a, 10b includes: Intake and exhaust sections 11a and 11b supply combustion-supporting gas and exhaust exhaust gas through heat storage bodies 12a and 12b disposed therein; First nozzles 21a, 21b are disposed inside the intake and exhaust sections 11a, 11b and discharge fuel; and second nozzles 22a, 22b that are disposed apart from the intake and exhaust sections 11a, 11b and discharge fuel along the flow direction of the oxidizing gas supplied from the intake and exhaust sections 11a, 11b. The present invention is characterized in that third nozzles 23a, 23b are added, which are arranged between the intake and exhaust sections 11a, 11b and the second nozzles 22a, 22b and discharge the fuel into the combustion-supporting gas supplied from the intake and exhaust sections 11a, 11b.

[0067] According to the above method, the above-mentioned new diffusion combustion can be easily added to the existing regenerative burners 10a and 10b. [Explanation of symbols]

[0068] 1...Furnace 2…Furnace wall 3…Inside the furnace 10a, 10b...Regenerative burner 11a, 11b...Supply / exhaust section 12a, 12b...heat storage body 14a, 14b...Air intake and exhaust ports 21a, 21b...First nozzle 22a, 22b...Second nozzle 23a, 23b...Third nozzle 31a, 31b...First valve 32a, 32b...Second valve 33a, 33b...Third valve 35a, 35b...Combustion support gas valve 36a, 36b...Exhaust gas valve 41…Fuel supply pipe 45...Combustion-supporting gas supply pipe 46...Exhaust gas discharge pipe 51...Air supply fan 53...Exhaust fan 55...Chimney F1...First Flame F2...Second flame F3…Third flame L1: Maximum flame length of the first flame L2-1: Maximum flame length of the second flame L2-2: Minimum flame length of the second flame L3: Flame length of the third flame

Claims

1. an intake / exhaust section that supplies combustion-supporting gas and exhausts exhaust gas through a heat storage body disposed inside; a first nozzle disposed inside the intake and exhaust unit and configured to discharge fuel; a second nozzle disposed apart from the intake and exhaust unit and configured to discharge the fuel along a flow direction of the combustion-supporting gas supplied from the intake and exhaust unit; a third nozzle disposed between the intake and exhaust unit and the second nozzle, and configured to discharge the fuel into the combustion-supporting gas supplied from the intake and exhaust unit, A regenerative burner characterized in that a first valve, a second valve, and a third valve are provided in a fuel supply pipe that supplies fuel to the first nozzle, the second nozzle, and the third nozzle, respectively, to adjust the amount of fuel supplied to each nozzle, and the flame length of the third flame produced by the third nozzle is adjustable to include the maximum flame length of the first flame produced by the first nozzle and the minimum flame length of the second flame produced by the second nozzle.

2. 2. The regenerative burner according to claim 1, wherein the third nozzle is configured to inject the fuel obliquely toward the flow of the combustion-supporting gas.

3. 2. The regenerative burner according to claim 1, wherein the fuel is discharged from the first nozzle and the third nozzle.

4. an intake / exhaust section that supplies combustion-supporting gas and exhausts exhaust gas through a heat storage body disposed inside; a first nozzle disposed inside the intake and exhaust unit and configured to discharge fuel; a second nozzle disposed apart from the intake and exhaust section and configured to discharge fuel along the flow direction of the combustion-supporting gas supplied from the intake and exhaust section, a third nozzle is added, the third nozzle being disposed between the intake and exhaust unit and the second nozzle and discharging the fuel into the combustion-supporting gas supplied from the intake and exhaust unit; A method for modifying a regenerative burner, characterized in that a first valve, a second valve, and a third valve are provided in fuel supply pipes that supply fuel to the first nozzle, the second nozzle, and the third nozzle, respectively, to adjust the amount of fuel supplied to each nozzle, and the flame length of the third flame produced by the third nozzle is adjustable to include the maximum flame length of the first flame produced by the first nozzle and the minimum flame length of the second flame produced by the second nozzle.

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