JP3942466B2 - Single-ended radiant tube combustion device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-ended radiant tube combustion apparatus.
[0002]
[Prior art]
Such a single-ended radiant tube combustion apparatus is used as a heat source for industrial furnaces such as metal melting and heat treatment, and indirectly burns gaseous fuel in a radiant tube with a closed end to indirectly heat an object to be heated. Heating.
Conventionally, as shown in FIG. 6, a combustion cylinder 40 having both ends opened is provided in the radiant tube 1 with the tip thereof facing the closed tip side of the radiant tube 1 and with a gap between the closed tip. It was.
Then, from the base end side of the radiant tube 1 toward the tip end side, a fuel supply part 41 that supplies the gas fuel G to the center of the combustion cylinder 40 and an outer peripheral side of the gas fuel G supplied from the fuel supply part 41 From the front end side of the radiant tube 1 through an oxygen-containing gas supply section 42 that supplies the combustion oxygen-containing gas A into the combustion cylinder 40 in a state of flowing in a cylindrical shape, and an annular space between the combustion cylinder 40 and the radiant tube 1. An exhaust part 43 for exhausting the combustion gas E flowing toward the base end side is provided, a flame F is formed in the combustion cylinder 40 so as to extend toward the tip of the radiant tube 1, and the combustion gas E is supplied to the radiant tube. 1 is inverted at the tip of 1 to flow through the annular space between the combustion cylinder 40 and the radiant tube 1 and discharge from the exhaust part 43.
[0003]
[Problems to be solved by the invention]
By the way, in such a single end type radiant tube combustion apparatus, heating is performed via the radiant tube.
However, in the conventional single-ended radiant tube combustion device, the combustion cylinder contributes slightly to the improvement of the radiation rate, but does not directly contribute to heating, but completes the combustion of gas fuel. Although indispensable, there were various problems due to the combustion cylinder as described below.
That is, since the number of parts is increased, the material cost is increased, and the configuration is complicated and the manufacturing operation is complicated, which causes an increase in cost and is difficult to reduce the cost.
Also, if the combustion cylinder deforms and contacts the radiant tube, the radiant tube may become abnormal, or if the combustion cylinder burns out, the combustion becomes unstable, so not only the inspection of the radiant tube but also the combustion Although inspection of the cylinder is necessary, since the combustion cylinder is located in the radiant tube, the inspection operation of the combustion cylinder is complicated, and further maintenance is complicated.
[0004]
The present invention has been made in view of such circumstances, and an object thereof is to reduce the cost and simplify the maintenance of a single-ended radiant tube combustion apparatus.
[0005]
[Means for Solving the Problems]
[Invention of Claim 1]
The characteristic configuration according to claim 1 is a fuel supply unit that supplies gas fuel in a cylindrical shape along the inner peripheral surface of the radiant tube from the proximal end side of the radiant tube with the distal end closed toward the distal end side;
An annular air outlet serving as an oxygen-containing gas supply unit that supplies the combustion-containing oxygen-containing gas in a swirling state to the inner side of the gas fuel supplied in a cylindrical shape from the fuel supply unit;
An exhaust part for exhausting the combustion gas flowing from the distal end side to the proximal end side of the radiant tube through the central part of the radiant tube is provided,
A flame is formed so as to extend along the inner peripheral surface of the radiant tube toward the tip side of the radiant tube, the combustion gas is reversed at the tip of the radiant tube, and the inner side of the flame is caused to flow. It exists in being comprised so that it may exhaust from an exhaust part.
According to the characteristic configuration of the first aspect, the gas fuel is supplied in a cylindrical shape along the inner peripheral surface of the radiant tube at the fuel supply unit, and the combustion oxygen-containing gas swirls at the oxygen-containing gas supply unit. In this state, the fuel gas is supplied to the inner side of the gas fuel supplied in a cylindrical shape from the fuel supply unit, and the flame is formed to extend to the tip side of the radiant tube along the inner peripheral surface of the radiant tube. However, it reverses at the front end in the radiant tube, flows inward from the flame toward the base end side of the radiant tube, and is discharged at the exhaust section.
That is, the gas fuel is supplied in a cylindrical shape along the inner peripheral surface of the radiant tube, and the combustion oxygen-containing gas is supplied in a swirling state to the inner side of the gas fuel supplied in such a cylindrical shape. Therefore, the gas fuel flows along the inner peripheral surface of the radiant tube by the centrifugal force of the combustion oxygen-containing gas and is mixed with the combustion oxygen-containing gas, so that the flame is formed on the inner peripheral surface of the radiant tube. It is formed so as to extend along the distal end side of the radiant tube.
The combustion gas is reversed at the distal end in the radiant tube, flows on the inner side of the flame toward the proximal end side of the radiant tube, and is discharged at the exhaust section.
Combustion airflow that flows in a cylindrical shape along the inner peripheral surface of the radiant tube toward the distal end side of the radiant tube (hereinafter sometimes referred to as an external flow) and the inner side of the cylindrical external flow is the proximal end of the radiant tube The boundary of the combustion airflow that flows toward the side (hereinafter sometimes referred to as the internal flow) is likely to disturb the combustion airflow, and the mixing of the gas fuel and the oxygen-containing gas for combustion is influenced by this boundary. Although the combustion oxygen-containing gas flows in a swirling state on the inner side of the gas fuel that flows in a cylindrical shape, the gas fuel is separated from the internal flow by the centrifugal force of the combustion oxygen-containing gas. Since it becomes easy to flow, it is possible to generate a layer having a high oxygen concentration at the boundary between the external flow and the internal flow, and to suppress the influence of the internal flow on the flame formation in the layer having the high oxygen concentration. To ensure stable combustion But they can.
In other words, since it becomes possible to stably complete the combustion in the radiant tube without using a conventional combustion cylinder, the material cost is reduced and the configuration is simplified because the combustion cylinder is not used. Since the manufacturing work is simplified, it is possible to reduce the cost and the conventional inspection of the combustion cylinder becomes unnecessary.
Therefore, in the single-end type radiant tube combustion apparatus, it has become possible to reduce the cost and simplify the maintenance.
[0006]
[Invention of Claim 2]
According to a second aspect of the present invention, the oxygen-containing gas path that guides the combustion oxygen-containing gas to the oxygen-containing gas supply unit is as viewed in the direction of supply of the combustion oxygen-containing gas from the oxygen-containing gas supply unit. An annular shape that surrounds the outer periphery of the exhaust path that guides the combustion gas discharged from the exhaust part, and is configured so that the oxygen-containing gas for combustion is supplied from the outlet side in the exhaust path,
The oxygen-containing gas passage and the exhaust passage are configured to exchange heat between the combustion oxygen-containing gas flowing through the oxygen-containing gas passage and the combustion gas flowing through the exhaust passage.
According to the characteristic configuration of the second aspect, the combustion gas flows in the exhaust passage in the direction from the distal end side to the proximal end side of the radiant tube toward the outlet, and contains the annular oxygen containing the outer periphery of the exhaust passage. The combustion oxygen-containing gas flows in the gas path in the direction from the proximal end side to the distal end side of the radiant tube, and heat is exchanged between the combustion oxygen-containing gas flowing in the oxygen-containing gas path and the combustion gas flowing in the exhaust path. Thus, the oxygen-containing gas is preheated with the combustion gas.
The fuel supply unit, the oxygen-containing gas supply unit, and the exhaust unit are arranged from the outside to the inside in the order of description, and the fuel supply unit is located on the outermost periphery, so that the gas fuel is guided to the fuel supply unit. Since the fuel passage is also located at the outer periphery of the annular oxygen-containing gas passage surrounding the outer periphery of the exhaust passage, that is, the outermost periphery, in order to increase the length of the oxygen-containing gas passage and the exhaust passage in order to increase the exhaust heat recovery efficiency. Can be made longer without being limited to the outermost fuel path. That is, it is possible to increase the exhaust heat recovery efficiency by lengthening the oxygen-containing gas path and the exhaust path without lengthening the fuel path.
On the other hand, conventionally, as shown in FIG. 6, the fuel supply unit 41, the oxygen-containing gas supply unit 42, and the exhaust unit 43 are arranged from the inside to the outside in the order of description, and the fuel supply unit 41 is located on the innermost periphery. Therefore, the oxygen-containing gas passage 44 that leads the combustion oxygen-containing gas A to the oxygen-containing gas supply unit 42 in the direction of supplying the combustion oxygen-containing gas from the oxygen-containing gas supply unit 42 is connected to the fuel supply unit 41. The exhaust passage 46 that guides the combustion gas E discharged from the exhaust part 43 is configured in an annular shape that surrounds the outer periphery of the oxygen-containing gas passage 44. Since the fuel passage 45 is located on the innermost periphery, when the lengths of the oxygen-containing gas passage 44 and the exhaust passage 46 are increased in order to increase the exhaust heat recovery efficiency, the fuel passage 45 located on the inner side of the fuel passage 45 is disposed. It will be regulated. In other words, in order to increase the length of the oxygen-containing gas path 44 and the exhaust path 46 in order to increase the exhaust heat recovery efficiency, it is necessary to lengthen the fuel path 45 correspondingly, and the configuration becomes complicated.
Therefore, according to the characteristic configuration of the second aspect, it is possible to lengthen the oxygen-containing gas path and the exhaust path without increasing the length of the fuel path, thereby increasing the exhaust heat recovery efficiency. While simplifying and reducing the cost, it has become possible to increase the heat recovery efficiency and improve the heat efficiency.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 and 3, the flow of the gas fuel G is indicated by a solid arrow, the flow of the combustion air A as the combustion oxygen-containing gas is indicated by a one-dot chain arrow, and the flow of the combustion gas E is indicated by a broken arrow. Is shown.
As shown in FIGS. 1 to 3, the single-ended radiant tube combustion apparatus combusts a radiant tube 1 whose tip is closed, and gas fuel G in the radiant tube 1 at the proximal end side of the radiant tube 1. And a burner B provided as described above.
[0008]
The burner B includes a plurality of fuel ejection holes 2 serving as fuel supply portions that supply the gaseous fuel G in a cylindrical shape along the inner peripheral surface of the radiant tube 1 from the proximal end side to the distal end side of the radiant tube 1. The air discharge port 3 serving as an oxygen-containing gas supply unit that supplies the combustion air A in a swirling state to the inner side of the gas fuel G supplied in a cylindrical shape from the fuel injection hole 2, and the central portion of the radiant tube 1 And an exhaust port 4 as an exhaust part for exhausting the combustion gas E flowing from the distal end side to the proximal end side of the radiant tube 1 through the radiant tube 1, and the flame F along the inner peripheral surface of the radiant tube 1. It is formed so as to extend to the front end side, and the combustion gas E is reversed at the front end in the radiant tube 1 so that the inner side of the flame F flows and is discharged from the exhaust port 4.
[0009]
The burner B will be described based on FIGS.
The inner cylinder 5, the intermediate cylinder 6 and the outer cylinder 7, which are each cylindrical and have a large diameter in the order of description, are arranged on the same axis in a triple manner. The outer diameter of the outer cylinder 7 is substantially the same as the inner diameter of the radiant tube 1 so that the outer cylinder 7 can be fitted into the proximal end of the radiant tube 1. The distal end of the intermediate cylinder 6 protrudes beyond the distal end of the outer cylinder 7, the distal end of the inner cylinder 5 protrudes beyond the distal end of the intermediate cylinder 6, and the proximal end of the intermediate cylinder 6 protrudes beyond the proximal end of the outer cylinder 7. The base end of the inner cylinder 5 is protruded from the base end of the intermediate cylinder 6.
[0010]
An annular body 8 having a plurality (eight in this embodiment) of fuel injection holes 2 formed at equal intervals in the circumferential direction is formed by an annular opening formed by the tip edge of the outer cylinder 7 and the outer peripheral surface of the intermediate cylinder 6. And the base end of the outer cylinder 7 is closed, and an annular space formed between the intermediate cylinder 6 and the outer cylinder 7 is used as a fuel passage 9 for guiding the gas fuel G to the plurality of fuel injection holes 2. A fuel receiving port 10 for receiving the gas fuel G into the fuel passage 9 is provided on the base end side of the outer cylinder 7 so as to function.
[0011]
An annular opening formed by the distal end edge of the intermediate cylinder 6 and the outer peripheral surface of the inner cylinder 5 is made to function as the air discharge port 3, the proximal end of the intermediate cylinder 6 is closed, and the inner cylinder 5 and the intermediate cylinder 6 are An annular space formed between them is caused to function as an air passage 11 as an oxygen-containing gas passage that guides combustion air A to the air discharge port 3, and swirl vanes 12 are disposed in the air passage 11. The combustion air A flowing in the air passage 11 is swirled by passing through the swirl vanes 12, and an air receiving port 13 for receiving the combustion air A is provided on the proximal end side of the intermediate cylinder 6. It is.
[0012]
The circular opening at the tip of the inner cylinder 5 is made to function as the exhaust port 4, and the inside of the inner cylinder 5 is made to function as the exhaust path 14 that guides the combustion gas E discharged from the exhaust port 4. The opening is configured to function as the outlet 15 of the exhaust passage 14.
[0013]
That is, the air passage 11 that guides the combustion air A to the air discharge port 3 from the exhaust port 4 as viewed from the combustion air discharge direction from the air discharge port 3 (corresponding to the combustion oxygen-containing gas supply direction view). Combustion air A is supplied from the outlet 15 side in the exhaust passage 14 in an annular shape that surrounds the outer periphery of the exhaust passage 14 that guides the exhausted combustion gas E.
[0014]
The burner B configured as described above is assembled to the radiant tube 1 with the distal end side of the outer cylinder 7 fitted into the proximal end of the radiant tube 1.
A fuel supply path 16 that leads a gas fuel G such as city gas is connected to the fuel inlet 10, and an air supply path 18 that leads the combustion air A from the air supply fan 17 is connected to the air inlet 13, In addition, a combustion gas lead-out path 20 that guides the combustion gas E sucked by the exhaust fan 19 is connected to the outlet 15 of the exhaust path 4. However, the exhaust fan 19 is used only when it is necessary to keep the internal pressure of the radiant tube 1 at a negative pressure.
[0015]
Then, the gas fuel G supplied through the fuel supply path 16 is guided through the fuel path 9, ejected from the plurality of fuel ejection holes 2 into a cylindrical shape along the inner peripheral surface of the radiant tube 1, and supplied through the air supply path 18. The combustion air A is guided through the air passage 11 and swirled by the swirl vanes 12 so that the combustion air A is ejected from the annular air discharge port 3 into a cylindrical shape from the plurality of fuel ejection holes 2. The fuel G is discharged while swirling inward, and the flame F is formed so as to extend along the inner peripheral surface of the radiant tube 1 toward the distal end side of the radiant tube 1, and the combustion gas E is formed in the radiant tube 1. Inverted at the tip, the inner side of the flame F is caused to flow and discharged from the exhaust port 4 to the exhaust path 14, guided through the exhaust path 14, and discharged through the combustion gas outlet path 20.
[0016]
For example, when the single-ended radiant tube combustion apparatus configured as described above is used for heating the inside of the furnace, the radiant tube 1 is inserted into the tube insertion hole 31 formed in the furnace wall 30 as shown in FIG. Is provided so as to protrude from the front end side into the furnace 32, and the furnace 32 is indirectly heated through the radiant tube 1.
[0017]
Hereinafter, the second embodiment of the present invention will be described. In the second embodiment, the same constituent elements as those in the first embodiment and the constituent elements having the same actions are denoted by the same reference numerals in order to avoid redundant description. The description is omitted, and a configuration different from the first embodiment will be mainly described.
[0018]
As shown in FIGS. 4 and 5, in the second embodiment, the inner cylinder 5 is surrounded by a plurality of strip-shaped fins 21 in a posture along the longitudinal direction of the inner cylinder 5 in a state of projecting inward and outward. As in the first embodiment, the air passage 11 that leads the combustion air A to the air discharge port 3 is exhausted as viewed from the combustion air discharge direction from the air discharge port 3. Combustion air A is supplied from an annular shape surrounding the outer periphery of the exhaust passage 14 that guides the combustion gas E discharged from the port 4 and from the outlet 15 side of the exhaust passage 14.
Then, the air passage 11 and the exhaust passage 14 are configured to exchange heat between the combustion air A flowing through the air passage 11 and the combustion gas E flowing through the exhaust passage 14, and the exhaust heat of the combustion gas E is recovered. Thus, a heat exchanger 22 for preheating the combustion air A is provided.
[0019]
And in providing the heat exchanger 22 as mentioned above, the outer cylinder 7 is made into the state close | similar to the base end side of the radiant tube 1 like 1st Embodiment, However, The intermediate | middle cylinder 6 and the outer cylinder 7 are Compared to the first embodiment, the radiant tube 1 is extended in the direction from the distal end to the proximal end, and the air passage 11 and the exhaust passage 14 are lengthened to increase the exhaust heat recovery efficiency.
[0020]
Then, in order to increase the length of the air passage 11 and the exhaust passage 14 so as to increase the exhaust heat recovery efficiency, the fuel passage 9 is arranged on the outermost periphery in the arrangement form of the air passage 11, the exhaust passage 14 and the fuel passage 9. Therefore, the air passage 11 and the exhaust passage 14 can be made long without being limited to the outermost fuel passage 9. That is, it is possible to lengthen the air path 11 and the exhaust path 14 without increasing the length of the fuel path 9 and increase the exhaust heat recovery efficiency.
[0021]
[Another embodiment]
Next, another embodiment will be described.
(A) The fuel supply unit is not limited to the case where the fuel supply unit is constituted by a plurality of fuel injection holes 2 drilled in the annular body 8 as exemplified in the above embodiment. For example, a plurality of cylindrical nozzles are attached to the annular body 8 at intervals in the circumferential direction, and the plurality of cylindrical nozzles are configured, or an annular slit is formed in the annular body 8 and the annular slit is formed. You may comprise.
Further, when the fuel supply unit is constituted by a plurality of fuel injection holes 2 as in the above embodiment, the number of fuel injection holes 2 can be changed.
[0022]
(B) Combustion oxygen-containing gas supplied from the oxygen-containing gas supply unit into the radiant tube 1 is a mixture of air and the combustion gas E discharged from the radiant tube 1 in addition to the air exemplified in the above embodiment. In addition, various things such as oxygen-enriched air having a high oxygen content can be used.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a single-end radiant tube combustion apparatus according to a first embodiment, taken along a longitudinal direction of the radiant tube. FIG. FIG. 3 is a cross-sectional view taken along the longitudinal direction of the radiant tube. FIG. 3 is a view taken along the line II in FIG. 2. FIG. 4 is a longitudinal view of the main part of the single-ended radiant tube combustion apparatus according to the second embodiment FIG. 5 is a cross-sectional view taken along the line in FIG. 4. FIG. 6 is a cross-sectional view taken along the longitudinal direction of the radiant tube of a conventional single-ended radiant tube combustion apparatus.
DESCRIPTION OF SYMBOLS 1 Radiant tube 2 Fuel supply part 3 Oxygen containing gas supply part 4 Exhaust part 11 Oxygen containing gas path 14 Exhaust path A Combustion oxygen containing gas E Combustion gas F Flame G Gas fuel

Claims (2)

A fuel supply section that supplies gas fuel in a cylindrical shape along the inner peripheral surface of the radiant tube from the proximal end side of the radiant tube with the distal end closed toward the distal end side;
An annular air outlet serving as an oxygen-containing gas supply unit that supplies the combustion-containing oxygen-containing gas in a swirling state to the inner side of the gas fuel supplied in a cylindrical shape from the fuel supply unit;
An exhaust part for exhausting the combustion gas flowing from the distal end side to the proximal end side of the radiant tube through the central part of the radiant tube is provided,
A flame is formed so as to extend along the inner peripheral surface of the radiant tube toward the tip side of the radiant tube, the combustion gas is reversed at the tip of the radiant tube, and the inner side of the flame is caused to flow. A single-ended radiant tube combustion apparatus configured to discharge from an exhaust section. An oxygen-containing gas path that guides the combustion-containing oxygen-containing gas to the oxygen-containing gas supply unit guides the combustion gas discharged from the exhaust unit as viewed from the direction of supply of the combustion-containing oxygen-containing gas from the oxygen-containing gas supply unit An annular shape that surrounds the outer periphery of the exhaust passage, and is configured such that the oxygen-containing gas for combustion is supplied from the outlet side in the exhaust passage,
The single according to claim 1, wherein the oxygen-containing gas passage and the exhaust passage are configured to exchange heat between a combustion oxygen-containing gas flowing through the oxygen-containing gas passage and a combustion gas flowing through the exhaust passage. End type radiant tube combustion device.

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