Combustion device

Abstract

To prevent various problems from occurring by unifying a pressure distribution of air supplied to a combustion device.SOLUTION: An inner tube body 15 is disposed in a blasting tube 12. Fuel injection nozzles 27, 35 are provided in one end side of the inner tube body 15. An annular space between the blasting tube 12 and the inner tube body 15 is set as a supply route 37 of combustion air. An inflow port 45 of combustion air 18 to the supply route 37 of combustion air is formed between the other end side of the inner tube body 15 and the blasting tube 12. A part in which at least the inflow port 45 is formed in the blasting tube 12 is disposed in a wind box 11. A bell mouth 46 is provided in a part in which the inflow port 45 of combustion air in an edge 14 of the blasting tube 12 is formed. The bell mouth 46 is within a range of an inclination angle θ of 45 to 60 degrees relative to an axial center 50 of the blasting tube 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a combustion apparatus, and more particularly to a combustion apparatus that can be suitably used in a boiler or the like. [Background technology]

[0002] Patent Document 1 describes a combustion device in which a tubular fuel nozzle is disposed inside a blast tube provided in a wind box, the annular space between the blast tube and the fuel nozzle is used as a combustion air supply path, a fuel outlet is formed at one end of the fuel nozzle, a combustion air outlet is formed between one end of the fuel nozzle and one end of the blast tube, an annular combustion air inlet is formed between the other end of the fuel nozzle and the other end of the blast tube, and at least the part of the blast tube where the combustion air inlet is formed is disposed inside the wind box.

[0003] In the combustion device of Patent Document 1, the annular combustion air inlet formed between the other end of the tubular fuel nozzle and the other end of the blast tube is formed in an annular shape between the outer periphery of the tubular fuel nozzle and the end of the blast tube by forming the blast tube shorter than the fuel nozzle. The outer diameter of this annular combustion air inlet is equal to the inner diameter of the blast tube and is equal to the outer diameter of the tubular fuel nozzle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-294505 Summary of the Invention [Problem to be solved by the invention]

[0005] In the combustion device described in Patent Document 1, if the pressure distribution of the combustion air in the wind box becomes uneven, this can affect the combustion state and cause the generated flame to become eccentric. If the flame becomes eccentric, there is a risk of misfire or flame extinguishing, and if the eccentric flame collides with the wall of the combustion furnace in which the combustion device is installed, there is a risk of carbon monoxide (CO) being generated due to the overheating of the wall.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to prevent the occurrence of the above-mentioned various problems by making the pressure distribution of the air supplied to the combustion device uniform. [Means for solving the problem]

[0007] To achieve this object, the combustion device of the present invention comprises: An inner tube body is disposed inside the blast tube, a fuel ejection nozzle is provided on one end side of the inner tube body, and an annular space between the blast tube and the inner tube body serves as a supply path for combustion air, a combustion air inlet for the combustion air supply passage is formed between the other end of the inner tube body and an end of the blast tube opposite to the fuel ejection nozzle installation side, At least a portion of the blast tube in which an inlet for combustion air is formed is disposed inside the wind box; A bell mouth is provided at a portion where an inlet for combustion air is formed at an end of the blast tube, The bell mouth is characterized in that its inclination angle with respect to the axis of the blast tube is in the range of 45 to 60 degrees.

[0008] In this configuration, by providing a bellmouth and setting its inclination angle in the range of 45 to 60 degrees, the combustion air that flows through the inlet and then through the annular supply passage has a uniform pressure distribution along the circumferential direction of the supply passage, thereby solving various problems caused by non-uniform pressure distribution.

[0009] According to the combustion device of the present invention, The other end of the inner tube body is provided at a position farther from the one end of the inner tube body than the inlet of the combustion air of the blast tube, It is preferable that a straightening tube be provided on the outer periphery of the inner tube body at a position away from the one end of the inner tube body relative to the combustion air inlet of the blast tube, for guiding the combustion air in the wind box through the combustion air inlet of the blast tube to the combustion air supply path.

[0010] By providing a straightening tube that guides the combustion air in the wind box through the combustion air inlet of the blast tube and into the combustion air supply passage, the pressure distribution of the combustion air flowing through the supply passage along the circumferential direction of the supply passage becomes more uniform.

[0011] In the combustion apparatus of the present invention, it is preferable that the straightening tube is arranged with its axis aligned with the blast tube. In this case, it is even more preferable for the sake of uniform pressure distribution that one end of the straightening tube is arranged facing the combustion air inlet of the blast tube and the other end of the straightening tube is provided with an orifice for controlling the flow state of the combustion air sent to the supply passage between the inner tube body and the blast tube.

[0012] According to the combustion apparatus of the present invention, the orifice can specifically be configured to have a flange-shaped body provided on the flow straightening tube and a plurality of air passage openings provided along the circumferential direction of the flange-shaped body. Effect of the Invention

[0013] According to the present invention, by providing a bellmouth, the pressure distribution of the combustion air in the combustion device can be made uniform, and by providing a flow straightening tube, the pressure distribution of the combustion air in the combustion device can be made even more uniform. [Brief description of the drawings]

[0014] [Figure 1]1 is a vertical sectional view of a combustion apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an enlarged view showing the main part in FIG. 1 in detail. [Diagram 3] FIG. 3 is a view of the rectifier tube depicted in FIG. 2 as seen from the end face side. [Figure 4] FIG. 1 is a conceptual diagram showing the flow of air in a combustion device equipped with only a bellmouth. [Diagram 5] FIG. 2 is a conceptual diagram showing the flow of air in a combustion device equipped with a bellmouth and a flow straightener. [Figure 6] FIG. 13 is a diagram showing measurement positions of pressure distribution. [Figure 7] FIG. 7 is a diagram showing the measurement results of pressure distribution at the measurement positions in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A combustion device 10 according to an embodiment of the present invention shown in Fig. 1 is used in a boiler 1. The combustion device 10 is attached to the boiler 1 having a furnace wall 2, thereby performing necessary combustion in the combustion chamber 3 of the boiler 1. A wind box 11 is attached to the furnace wall 2 of the boiler 1. The combustion device 10 is disposed horizontally and installed in a state in which it penetrates the wind box 11 and the furnace wall 2.

[0016] The combustion device 10 has a blast tube 12. The blast tube 12 has a tip 13 disposed at the position of the furnace wall 2, and the other end 14 disposed inside the wind box 11.

[0017] An inner tube body 15 is concentrically disposed inside the blast tube 12. The inner tube body 15 has an outer tube 16 on the outside along the radial direction, and an inner tube 17 disposed inside the outer tube 16. The outer tube 16 and the inner tube 17 are concentrically disposed with each other.

[0018] The blast tube 12 is supported by the components constituting the wind box 11 , the outer tube 16 is supported by the blast tube 12 , and the inner tube 17 is supported by the outer tube 16 .

[0019] A duct 19 for supplying combustion air 18 to the wind box 11 is connected to the wind box 11. The duct 19 is connected to the wind box 11 at a position spaced apart from the furnace wall 2 along the axial direction of the blast tube 12.

[0020] Although not shown, the duct 19 is provided with a damper for adjusting the amount of combustion air 18 supplied to the wind box 11. The opening degree of the damper is adjusted by an actuator such as a motor (not shown).

[0021] A manifold chamber 20 is attached to the portion of the wind box 11 opposite to the furnace wall 2. The outer tube 16 and the inner tube 17 of the inner tube body 15 are formed to a length that reaches the inside of the manifold chamber 20 after passing through the furnace wall 2 and the wind box 11. In contrast, the blast tube 12 is only formed from the furnace wall 2 to the inside of the wind box 11, and does not reach the inside of the manifold chamber 20.

[0022] A flame funnel 21 is connected to the tip 13 of the blast tube 12 at the position of the furnace wall 2 of the boiler 1. An opening 22 is formed in the portion of the flame funnel 21 facing the combustion chamber 3 of the boiler 1. The opening 22 ejects combustion gas 30 generated in a combustion section 23 formed inside the flame funnel 21 in the vicinity of this opening 22 into the combustion chamber 3 of the boiler 1. The inner tube body 15, i.e., the outer tube 16 and the inner tube 17, are formed with a length that reaches the combustion section 23.

[0023] A supply pipe 25 for liquid fuel 24 enters the manifold chamber 20 from a position farther from the furnace wall 2 than the manifold chamber 20, enters the inside of the inner tube 17 from an opening 26 at the end of the inner tube 17 in the manifold chamber 20, and reaches the combustion section 23. The supply pipe 25 is supported by the inner tube 17. In the combustion section 23, a liquid fuel ejection nozzle 27, which is an ejection nozzle for the liquid fuel 24, is provided at the tip of the supply pipe 25. The liquid fuel ejection nozzle 27 ejects the liquid fuel 24 supplied by the supply pipe 25 into the combustion section 23.

[0024] An ignition electrode 28 is provided near the liquid fuel ejection nozzle 27 for igniting the liquid fuel 24 that is ejected from the liquid fuel ejection nozzle 27 and mixed with the combustion air 18. The ignition electrode 28 generates a discharge spark to ignite the liquid fuel 24 mixed with the combustion air 18. A conductor 29 for supplying high voltage electricity for discharge to the ignition electrode 28 is connected to the ignition electrode 28. The conductor 29 is inserted into the manifold chamber 20 from the outside, and is disposed inside the inner tube 17 along the supply pipe 25 for the liquid fuel 24, and is electrically connected to the ignition electrode 28.

[0025] An opening 31 that opens in the radial direction of the outer tube 16 is formed in the outer tube 16 at a position inside the manifold chamber 20 closer to the wind box 11 than the opening 26 of the inner tube 17. A connection port 32 is connected to the opening 31. The connection port 32 can feed gaseous fuel 33 from outside the manifold chamber 20 to the opening 31.

[0026] An annular gas fuel supply passage 34 is formed between the inner peripheral surface of the outer tube 16 and the outer peripheral surface of the inner tube 17 in the inner tube body 15. The gas fuel supply passage 34 communicates with the opening 31, and therefore the gas fuel 33 is led to the gas fuel supply passage 34 through the opening 31. In the outer tube 16, an ejection port is formed in the combustion section 23 for ejecting the gas fuel 33 from the gas fuel supply passage 34 into the inside of the blast tube 12 in the combustion section 23, thereby forming a gas fuel ejection nozzle 35.

[0027] An annular space is formed between the blast tube 12 and the outer tube 16 of the inner tube body 15, and this annular space forms an air supply passage 37 for supplying combustion air 18 toward the combustion section 23.

[0028] A pilot burner 39 is provided in the air supply passage 37 near the gas fuel outlet 35. The pilot burner 39 has a known configuration. A diffuser 40 is provided in the combustion section 23 at a position closer to the opening 22 of the flame funnel 21 than the liquid fuel outlet nozzle 27 and the gas fuel outlet 35.

[0029] In the illustrated combustion device 10, with the pilot burner 39 ignited, either or both of the gaseous fuel 33 and the liquid fuel 24 are ejected toward the combustion section 23 to operate the combustion device 10. Combustion air 18 required for combustion is supplied to the combustion section 23 from an air supply passage 37. Providing a diffuser 40 in the combustion section 23 ensures good combustion.

[0030] The introduction of the combustion air 18 from the wind box 11 to the air supply passage 37 will now be described.

[0031] As shown in FIG. 1 and FIG. 2, inside the wind box 11, an inlet 45 for the combustion air 18 to the air supply passage 37 is formed between the end of the blast tube 12 having a circular cross section and the end side of the inner tube body 15 (not shown in FIG. 2), i.e., the end side of the outer tube 16. A bell mouth 46 is provided at the portion of the blast tube 12 where the inlet 45 is formed. The bell mouth 46 has a small diameter portion 47 formed with a diameter corresponding to the diameter of the blast tube 12 and connected to the blast tube 12. The large diameter portion 48 of the bell mouth 46 is provided at a position farther from the combustion section 23 shown in FIG. 1 than the small diameter portion 47. Between the small diameter portion 47 and the large diameter portion 48 of the bell mouth 46, an inclined portion 49 is provided that is formed linearly in the longitudinal section of the bell mouth 46. As shown in FIG. 2, the inclined portion 49 has an inclination angle θ from the axis 50 of the blast tube 12. The small diameter portion 47 has a diameter D equal to the inner diameter of the blast tube 12. The large diameter portion 48 is formed to have a diameter d.

[0032] A rectifier tube 52 having a circular cross section and open at both ends is provided inside the wind box 11 between the bellmouth 46 and the manifold chamber 20. The rectifier tube 52 is arranged coaxially with the blast tube 12 and shares an axis 50 with the blast tube 12. The bore of the rectifier tube 52 is formed to be equal to the diameter of the blast tube 12. As a result, the rectifier tube 23 is provided on the outer periphery of the inner tube body 15 at a position farther from the combustion section 23 than the inlet 45 for the combustion air of the blast tube 12 as shown in FIG. 1. The rectifier tube 52 faces the bellmouth 46 at one end 53 and communicates with the manifold chamber 20 at the other end 54. As shown in FIG. 2, the end face of one end of the rectifier tube 52 is provided at a position distant by a distance h from the large diameter portion 48 of the bellmouth 46. In the illustrated example, h=0 as described later.

[0033] 1 and 2, an orifice 55 is provided on the outer periphery of the other end 54 of the rectifier tube 23. The orifice 55 has a plate-shaped flange 56 that is disposed along the outer periphery of the other end 54 of the rectifier tube 23 and is integrated with the rectifier tube 23, and a plurality of air passage holes 57 formed in a penetrating state along the circumferential direction of the flange 56. As shown in Fig. 3, the air passage holes 57 are formed in a circular shape, and a plurality of air passage holes 57 are formed at equal pitch along the circumferential direction of the flange 56.

[0034] 2, the flange-shaped body 56 is fastened together with the manifold chamber 20 to the wind box 11 by fastening elements 58 such as bolts and nuts. In this way, the rectifier tube 52 is installed in a predetermined position. At this time, an annular air passage portion 59 is formed in an open state between one end 53 of the rectifier tube 52 and the large diameter portion 48 of the bellmouth 46.

[0035] With this configuration, a portion 61 of the combustion air 18 flowing into the interior of the wind box 11 from the duct 19 shown in Figure 1 is introduced into the interior of the bellmouth 46 through the annular air passage 59 between one end 53 of the straightening tube 52 and the large diameter section 48 of the bellmouth 46, and is guided by the bellmouth 46 to be sent to the air supply passage 37.

[0036] The remaining portion 62 of the combustion air 18 that has flowed into the interior of the wind box 11 from the duct 19 passes through the air passage port 57 of the orifice 55 and flows from the wind box 11 into the manifold chamber 20. Most of the combustion air 18 that has flowed into the manifold chamber 20 immediately reverses its flow direction and enters the interior of the rectifier tube 52 from a portion of the opening of the other end 54 of the rectifier tube 52 that is on the outer circumferential side of the inner tube body 15. The combustion air 18 that has entered the interior of the rectifier tube 52 is guided by the rectifier tube 52 and introduced into the interior of the bellmouth 46 from the large diameter portion 48 of the bellmouth 46, and is guided by the bellmouth 46 and sent to the air supply passage 37 in the same manner as the combustion air 18 that has been introduced into the interior of the bellmouth 46 through the air passage portion 59.

[0037] A portion of the combustion air 18 that flows into the manifold chamber 20 is introduced into the interior of the inner tube 17 through an opening 26 of the inner tube 17, and then flows to the combustion section 23, where it is mixed with the liquid fuel 24 ejected from the liquid fuel ejection nozzle 27 and is used to combust the fuel.

[0038] The combustion air 18 that enters the air supply passage 37 from the bellmouth 46 is used for combustion by the pilot burner, and is mixed with the gaseous fuel 33 ejected from the gaseous fuel ejection nozzle 35 to be used for combustion of the gaseous fuel 33. The combustion air 18 in the air supply passage 37 is mixed with the liquid fuel 24 ejected from the liquid fuel ejection nozzle 27 separately from the combustion air 18 that has passed through the inside of the inner tube 17, and is used for combustion of the liquid fuel 24.

[0039] At this time, the combustion air 18 is guided by the bellmouth 46 and then introduced into the air supply passage 37, which effectively prevents the pressure distribution of the combustion air 18 in the air supply passage 37 from becoming uneven, particularly along the circumferential direction of the air supply passage 37. This prevents the flame from becoming eccentric in the combustion section 23 due to the uneven pressure distribution, and prevents the occurrence of situations such as misfire and extinguishing due to the eccentricity of the flame. In addition, it is effectively prevented that the flame will collide with the furnace wall of the combustion chamber 3 of the boiler 1 due to the eccentricity of the flame, thereby generating carbon monoxide (CO).

[0040] In the combustion apparatus 10 of the embodiment shown in Figures 1 to 3, in addition to the bellmouth 46, a straightening tube 52 is also provided. Therefore, due to the straightening effect of the straightening tube 52, the occurrence of uneven pressure distribution of the combustion air 18 in the air supply passage 37 is more reliably prevented.

[0041] 4 shows, with streamlines, the flow of the combustion air 18 in the combustion device 10 when only the bellmouth 46 is installed, without the flow straightener 52. It can be seen that by providing the bellmouth 46, it is possible to equalize the pressure distribution of the combustion air 18, and that in the combustion section 23 the combustion air 18 flows without turbulence.

[0042] 5 shows, with streamlines, the flow of the combustion air 18 in the combustion device 10 when both the bellmouth 46 and the rectifier tube 52 are installed. The rectifier tube 52 rectifies the combustion air 18 flowing inside the rectifier tube 52, so that the flow of the combustion air 18 entering the air supply passage 37 from the bellmouth 46 can be directed toward the combustion section 23, thereby making it possible to further uniform the pressure distribution of the combustion air 18.

[0043] In order to effectively realize such uniform pressure distribution, the inclination angle θ of the inclined portion of the bellmouth 46 shown in FIG. 2 must be 45° to 60°. The ratio of the diameter D of the small diameter portion 47 of the bellmouth 46 shown in FIG. 2 to the diameter d of the large diameter portion 48 is preferably d / D=1.6 to 2.0. The distance h between the end face of one end 53 of the rectifier tube 52 and the large diameter portion 48 of the bellmouth 46 is preferably h=0. In other words, it is preferable that the end face of one end 53 of the rectifier tube 52 and the large diameter portion 48 of the bellmouth 46 are present at the same position along the direction of the axis 50. Furthermore, it is preferable that the ratio of the opening area A of the annular air passage portion 59 between the one end 53 of the rectifier tube 52 and the large diameter portion 48 of the bellmouth 46 when viewed in the direction of the axis 50 to the total opening area A1 of the multiple air passage ports 57 is A / A1=5 to 10. By satisfying all of these conditions, the pressure distribution of the combustion air 18 can be reliably uniformed.

[0044] The pressure distribution of the combustion air 18 in the combustion section 23 of the combustion device 10 will now be described. According to the present invention, by providing the bellmouth 46, and in particular by providing both the rectifier tube 52 and the bellmouth 46, the pressure distribution of the combustion air 18 in the combustion section 23 shown in FIG. 1 can be made uniform along the circumferential direction of the combustion section 23.

[0045] The results of the pressure distribution measurements will now be described.

[0046] 6(a) and (b) show measurement positions a, b, c, and d for the pressure of the combustion air 18 in the combustion section 23. These measurement positions a, b, c, and d were set at 90° intervals along the circumferential direction of the combustion section 23. The pressure of the combustion air 18 was measured by a manometer.

[0047] Incidentally, the shape of the combustion section 23 is depicted differently in Fig. 6 and Fig. 1, etc., but this is for convenience of drawing, and there is no difference between the structures of the two in the actual machine. In general, Fig. 6 is depicted in some detail, whereas Fig. 1, etc. are depicted somewhat diagrammatically. Specifically, the pressure inlet to the manometer is formed in the combustion section 23 at a position immediately before the combustion air 18 is ejected.

[0048] Figure 7 shows the measurement results of the pressure distribution. As described above, measurement positions a, b, c, and d were at 90° intervals along the circumferential direction of the combustion section 23, so in Figure 7, measurement positions a and c are plotted on the vertical axis, and measurement positions b and d are plotted on the horizontal axis. The intersection of the vertical and horizontal axes is set as the origin, and the measured pressure values ​​are plotted so that they increase as the distance from the origin increases.

[0049] 7, the dotted line shows the measurement results when neither the rectifier tube 52 nor the bellmouth 46 was installed. The dashed line shows the measurement results when only the bellmouth 46 was installed, without the rectifier tube 52. The solid line shows the measurement results when both the rectifier tube 52 and the bellmouth 46 were installed.

[0050] 7, when neither the rectifier tube 52 nor the bellmouth 46 was provided, the measured pressure varied greatly at measurement positions a, b, c, and d, as shown by the dotted lines, and the pressure distribution was not uniform. Specifically, the pressure was high at measurement position d, but the pressure was lower at the other measurement positions a, b, and c than at measurement position d.

[0051] When the rectifier tube 52 was not provided and only the bellmouth 46 was provided, a significant improvement in the uniformity of the pressure distribution was observed, as shown by the dashed line, compared to the dotted line. In other words, compared to the dotted line, the measurement value at measurement position d decreased, and the measurement values ​​at measurement positions a and c increased toward the measurement value at measurement position d.

[0052] When both the rectifier tube 52 and the bellmouth 46 were provided, as shown by the solid line, the measured pressures at all measurement positions a, b, c, and d were nearly equal, and the pressure distribution was well-equalized. Moreover, as shown in the figure, the measured pressure value itself was significantly higher than in the cases of the dotted and dashed lines. From this, it can be seen that by providing both the rectifier tube 52 and the bellmouth 46, not only can the pressure distribution be made uniform, but also an increase in the amount of combustion air 18 due to the increase in pressure, i.e., an increase in the supply efficiency of the combustion air 18, can be realized.

[0053] This effect is particularly remarkable when the orifice 55 is provided in the flow straightening tube 52 and the orifice 55 has a plurality of air passage openings 57 at a constant pitch along the circumferential direction. [Explanation of symbols]

[0054] 12 Blast Tube 15 Inner tube body 18 Combustion air 27 Liquid fuel ejection nozzle 35 Gaseous fuel injection nozzle 37 Air supply line 45 Inlet 46 Bellmouth 50 axis θ Tilt angle 52 Rectifier tube 55 Orifice 56 Collar 57 Air passage

Claims

1. An inner tube body is disposed inside the blast tube, a fuel ejection nozzle is provided on one end side of the inner tube body, and an annular space between the blast tube and the inner tube body serves as a supply path for combustion air, a combustion air inlet for the combustion air supply passage is formed between the other end of the inner tube body and an end of the blast tube opposite to the fuel ejection nozzle installation side, At least a portion of the blast tube in which an inlet for combustion air is formed is disposed inside the wind box; A bell mouth is provided at a portion at the end of the blast tube where an inlet for combustion air is formed, A combustion apparatus characterized in that the inclination angle of the bell mouth with respect to the axis of the blast tube is in the range of 45 to 60 degrees.

2. The other end of the inner tube body is provided at a position farther from the one end of the inner tube body than the inlet of the combustion air of the blast tube, 2. The combustion apparatus according to claim 1, characterized in that a straightening tube is provided on the outer periphery of the inner tube body at a position away from the one end side of the inner tube body relative to the combustion air inlet of the blast tube, for guiding the combustion air in the wind box through the combustion air inlet of the blast tube to the combustion air supply passage.

3. 3. The combustion apparatus according to claim 2, wherein the rectifier tube is arranged with its axis aligned with that of the blast tube.

4. 4. A combustion apparatus according to claim 3, wherein one end of the straightening tube is arranged facing the combustion air inlet of the blast tube, and the other end of the straightening tube is provided with an orifice for controlling the flow state of the combustion air sent to the supply passage between the inner tube body and the blast tube.

5. 5. The combustion apparatus according to claim 4, wherein the orifice comprises a flange provided on the flow straightening pipe, and a plurality of air passage openings provided along the circumferential direction of the flange.

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