JP2008014581A - Radiant tube burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiant tube burner which is composed of the periphery of an attachment part of a gas burner by using metal or the like, is reduced in the size of the gas burner, and also reduced in an NOx generation amount. <P>SOLUTION: The radiant tube burner 1 has: a radiant tube 2; and a pair of gas burners 3, and the gas burner 3 has: a burner body 4; a burning tube; and a burner gun 6. A outer side passage 51 is formed between the radiant tube 2 and the burning tube 5, and an inner side passage 52 is formed between the burning tube 5 and the burner gun 6. The gas burner 3 is composed such that first stage combustion is carried out by using main air A1 contacting a first heat storage body 71 in the inner side passage 52 after its contact of fuel gas F jetted out from the burner gun 6 to a second heat storage body 72 in the burner body 4, and second stage combustion is carried out by using sub air A2 having passed through the outer side passage 51 after its contact to the second heat storage body 72 in the burner body 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiant tube burner configured to alternately burn in a pair of gas burners and to heat the inside of a heat treatment furnace by radiant heat from the radiant tube.

  In a radiant tube burner that alternately burns in a pair of gas burners, there is a radiant tube burner that burns in a radiant tube in order to prevent the burned combustion gas from coming into direct contact with the atmospheric gas in the heat treatment furnace. In this radiant tube burner, in order to utilize the exhaust heat of the exhaust gas after combustion, the heat storage body is disposed in the passage in the gas burner. And exhaust heat of exhaust gas is collect | recovered by the thermal storage body, the air for making it burn with fuel gas is made to contact with this thermal storage body, and the heated air is utilized for combustion.

As such a radiant tube burner, for example, there is a regenerative radiant tube combustion device disclosed in Patent Document 1.
In this heat storage type radiant tube combustion apparatus, a W-shaped radiant tube is disposed in a combustion furnace, and burners are disposed at both ends of the radiant tube fixed to the furnace wall. In this burner, a heat storage case (outer cylinder) comprising a fuel supply unit and a supply / exhaust passage for housing the heat storage member is provided on the outer surface of the furnace wall, Combustion cylinders that form a flame by burning the ejected gas fuel are connected.

However, in the said patent document 1, the thermal storage body is only arrange | positioned outside the furnace wall. As a result, the high-temperature exhaust gas that has passed through the radiant tube directly contacts the periphery of the burner mounting portion with respect to the furnace wall, and then the exhaust heat is recovered by the heat storage body. Therefore, the temperature around the burner mounting portion becomes high, and the material of the member used for this portion is restricted.
Moreover, in the said patent document 1, in order to increase the thermal storage capacity | capacitance by a thermal storage body, it is necessary to increase the capacity | capacitance of the case for thermal storage bodies arrange | positioned on the outer surface of the said furnace wall, and the size of an apparatus becomes large. End up.

JP 2003-279002 A

  The present invention has been made in view of such conventional problems, and the periphery of the gas burner mounting portion can be configured using metal or the like, and the heat storage capacity by the heat storage body without increasing the size of the gas burner. It is an object of the present invention to provide a radiant tube burner capable of increasing the amount of NOx and reducing the amount of NOx produced by combustion.

The present invention comprises a radiant tube disposed in a heat treatment furnace, and a pair of gas burners disposed at both ends of the radiant tube and alternately forming a combustion flame in the radiant tube. In the radiant tube burner configured to heat the inside of the heat treatment furnace by radiant heat,
The gas burner includes a burner body disposed on an outer surface of the furnace wall of the heat treatment furnace, a combustion cylinder inserted and disposed in the radiant tube from an opening on the furnace wall inner surface side of the burner body, and the combustion cylinder from the burner body. With a burner gun inserted and placed inside,
An outer passage communicating with the burner body is formed between the radiant tube and the combustion cylinder, and an inner passage communicating with the burner body is formed between the combustion cylinder and the burner gun. Formed,
A first heat storage body for recovering exhaust heat is disposed in the inner passage, and a second heat storage body for recovering exhaust heat is disposed in the burner body,
After the fuel gas ejected from the burner gun comes into contact with the second heat storage body in the burner body, the first stage combustion is performed using the main air in contact with the first heat storage body in the inner passage. In addition, a radiant tube burner configured to perform second-stage combustion using sub air that has passed through the outer passage after contacting the second heat storage body in the burner body. (Claim 1).

  In the radiant tube burner of the present invention, the passage in the burner body disposed on the outer wall surface of the heat treatment furnace is formed between the outer passage formed between the radiant tube and the combustion cylinder, and the combustion cylinder and the burner gun. Communicated with the inner passage. And the 1st heat storage body is arrange | positioned in an inner side channel | path, and the 2nd heat storage body is arrange | positioned in the burner body.

  Then, combustion is performed by one gas burner, and exhaust heat of exhaust gas after passing through the radiant tube is recovered by the first heat storage body and the second heat storage body in the other gas burner. At this time, exhaust gas comes into contact with the first heat storage body in the inner passage, whereby first-stage exhaust heat recovery is performed, and the temperature of the exhaust gas decreases. Further, at this time, the exhaust gas passing through the outer passage is removed by contact with the radiant tube and the combustion cylinder, and the temperature decreases. Thereby, the exhaust gas in a state where the temperature is lowered can be passed around the attachment portion of the gas burner to the outer surface of the furnace wall. Therefore, the structure around the gas burner mounting portion does not need to be configured using a refractory material such as ceramics, and can be configured using metal.

Further, the exhaust gas after the first stage exhaust heat recovery is brought into contact with the second heat storage body in the burner body, the second stage exhaust heat recovery is performed, and the temperature of the exhaust gas is further increased. descend. Thereby, exhaust gas exhaust heat recovery can be sufficiently performed.
Further, in the present invention, the heat storage capacity of the heat storage body is increased without increasing the size of the gas burner by arranging the first heat storage body using the inner passage between the combustion cylinder and the burner gun. Can be made.

  Further, when combustion is performed in the gas burner on the side where the exhaust heat recovery is performed, after contacting the second heat storage body in the burner body, the main air contacting the first heat storage body in the inner passage and the jet from the burner gun The first stage of combustion is performed by burning with the fuel gas. Thereby, a flame due to incomplete combustion rich in fuel at the first stage is formed from the inside of the combustion cylinder to the inside of the radiant tube.

And after contacting the 2nd thermal storage body in a burner body, the 2nd stage combustion is performed by supplying the sub air which passed the inside of an outside channel | path to the said flame. Thereby, in the radiant tube, the unburned part in the first stage combustion can be burned completely.
Thus, the amount of NOx generated can be reduced by performing two-stage combustion to suppress rapid combustion.

  Therefore, according to the radiant tube burner of the present invention, the periphery of the gas burner mounting portion can be configured using metal or the like, and the heat storage capacity of the heat storage body can be increased without increasing the size of the gas burner. And the amount of NOx produced by combustion can be reduced.

A preferred embodiment of the present invention described above will be described.
In the present invention, the burner gun is configured such that a fuel pipe for allowing the fuel gas to pass through is inserted into a cooling air pipe for allowing the cooling air to pass through and the fuel gas is ejected from the fuel pipe. It is preferable that flame holding is performed by burning a part of the cooling air and the cooling air ejected from the cooling air pipe.

In this case, the temperature of the gas nozzle at the tip of the combustion tube can be suppressed from being increased by the cooling air, and the gas nozzle can be protected from heat.
Further, by holding a part of the fuel gas using the cooling air, flame holding in the gas nozzle portion can be performed stably. Thereby, combustion in the gas burner can be further stabilized.

The combustion cylinder includes a first combustion cylinder portion that forms the inner passage with the burner gun, and a second combustion cylinder portion that is connected to a distal end portion of the first combustion cylinder portion. A combustion cylinder part can be comprised from a metal, and the said 2nd combustion cylinder part can be comprised from ceramics (Claim 3).
In this case, since the first combustion cylinder part is made of metal, it is easy to form a flange part projecting radially outward at the end part of the combustion cylinder or perform processing. In addition, by configuring the second combustion cylinder portion from ceramics, it is possible to improve the heat resistance of the portion on the tip end side that contacts the higher temperature exhaust gas or the combustion flame in the combustion cylinder.

Hereinafter, embodiments of the radiant tube burner of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the radiant tube burner 1 of the present example is provided with a radiant tube 2 disposed in the heat treatment furnace 8 and both ends of the radiant tube 2, and alternately forms a combustion flame in the radiant tube 2. And a pair of gas burners 3 configured to heat the inside of the heat treatment furnace 8 by radiant heat from the radiant tube 2.

  As shown in the figure, the gas burner 3 is inserted into the radiant tube 2 from the burner body 4 disposed on the furnace wall outer surface 801 of the heat treatment furnace 8 and the opening 401 on the furnace wall inner surface 802 side of the burner body 4. A combustion cylinder 5 and a burner gun 6 inserted from the burner body 4 into the combustion cylinder 5 are provided. Further, an outer passage 51 that communicates with the burner body 4 is formed between the radiant tube 2 and the combustion cylinder 5, and the combustion cylinder 5 and the burner gun 6 communicate with each other within the burner body 4. An inner passage 52 is formed.

  Further, a first heat storage body 71 that recovers exhaust heat is disposed in the inner passage 52, and a second heat storage body 72 that recovers exhaust heat is disposed in the body passage 41 of the burner body 4. is there. The gas burner 3 of the present example uses the fuel gas F ejected from the burner gun 6 to contact the second heat storage body 72 in the burner body 4 and then the main air A1 in contact with the first heat storage body 71 in the inner passage 52. The first stage combustion is performed, and the second stage combustion is performed using the sub air A2 that has passed through the outer passage 51 after contacting the second heat storage body 72 in the burner body 4. It is.

Hereinafter, the radiant tube burner 1 of this example will be described in detail with reference to FIGS.
In this example, the front end portion refers to the end portion on the furnace wall inner surface 802 side of the heat treatment furnace 8, and the rear end portion refers to the end portion on the furnace wall outer surface 801 side of the heat treatment furnace 8. Further, the front end side refers to the furnace wall inner surface 802 side, and the rear end side refers to the furnace wall outer surface 801 side.
In the present example, one gas burner 3 of the pair of gas burners 3 is illustrated, but the other gas burner 3 has the same structure.

As shown in FIG. 1, the radiant tube 2 of this example is made of heat-resistant cast steel having excellent heat resistance. At both ends of the radiant tube 2, radiant tube flanges 21 for fixing the end of the radiant tube 2 to the outer wall 801 of the furnace wall are formed.
The burner body 4 of this example has a cross-sectional outline larger than the cross-sectional outline of the combustion cylinder 5. The burner body 4 has an insertion hole 411 for inserting and arranging the burner gun 6, and an annular body passage 41 through which air (fresh air) passes is formed around the insertion hole 411. The burner body 4 is formed with an air inlet 412 for allowing air to flow into the body passage 41.

  Further, as shown in the figure, a body mounting flange 42 for mounting on the furnace wall outer surface 801 is formed at the end of the burner body 4 facing the furnace wall outer surface 801 so as to face the radiant tube flange 21. . The burner body 4 is fixed to the furnace wall outer surface 801 with a packing 422 sandwiched between the burner body 4 and the radiant tube flange 21.

  As shown in FIGS. 1 and 2, a flange hole 421 having an inner diameter larger than the outer diameter of the radiant tube 2 is formed in the body mounting flange 42 of the burner body 4. In addition, a partition plate 43 that protrudes radially outward is formed at an end portion of the cylindrical wall portion 410 that forms the periphery of the insertion hole 411 in the burner body 4 and that faces the furnace wall outer surface 801. The plate 43 is formed with a communication port 431 that allows the body passage 41 in the burner body 4 and the inner passage 52 in the combustion cylinder 5 to communicate with each other. The communication ports 431 are formed at a plurality of locations in the circumferential direction of the partition plate 43.

As shown in FIGS. 1 to 3, an air passage gap 54 is formed between the outer periphery of the combustion cylinder 5 and the outer periphery of the outer surface 801 of the combustion cylinder 5 of the present example. A combustion cylinder support flange 53 having a shape is arranged.
The combustion cylinder support flange 53 is formed with a gap forming hole 531 having an inner diameter larger than the outer diameter of the combustion cylinder 5. In addition, pin arrangement holes 532 that penetrate the combustion cylinder support flange 53 in the radial direction are formed at a plurality of positions in the circumferential direction of the combustion cylinder support flange 53 (four positions in the circumferential direction in this example). .

  As shown in the figure, the combustion cylinder 5 forms an air passage gap 54 between the combustion cylinder 5 and the gap formation hole 531 by the pin 533 inserted into the pin arrangement hole 532 of the combustion cylinder support flange 53. And fixed to the combustion cylinder support flange 53. Further, the outer periphery of the combustion cylinder support flange 53 is formed in a circular shape, and the combustion cylinder support flange 53 is inserted and disposed in a flange hole 421 formed in the body attachment flange 42. Thereby, the combustion cylinder 5 can be supported by the burner body 4 via the combustion cylinder support flange 53.

Thus, by supporting the combustion cylinder 5 by using the combustion cylinder support flange 53, it is not necessary to perform complicated processing on the combustion cylinder 5, and the entire combustion cylinder 5 is superior in heat resistance to metal or the like. It is also easy to construct from ceramics.
As shown in FIG. 2, the air passage gap 54 communicates the outer passage 51 between the radiant tube 2 and the combustion cylinder 5 and the body passage 41 in the burner body 4.

  As shown in FIGS. 1 and 2, a part (front end side portion) of the burner gun 6 of this example is inserted and arranged up to the rear end side portion of the combustion cylinder 5 on the furnace wall outer surface 801 side. The first heat storage body 71 of this example is arranged so as to fill a space between the rear end side portion of the combustion cylinder 5 and the front end side portion of the burner gun 6. The first heat storage body 71 is held between the partition plate 43 and a slip-out preventing protrusion 55 formed to protrude from the inner periphery of the combustion cylinder 5. The escape prevention protrusion 55 was welded to a hole formed in the combustion cylinder 5, and a ring-shaped support 551 was disposed between the escape prevention protrusion 55 and the first heat storage body 71.

  Further, the first heat storage body 71 of this example has a cylindrical shape along the shape between the inner periphery of the combustion cylinder 5 and the outer periphery of the burner gun 6. In addition, as the first heat storage body 71 of this example, a ceramic foam made of a porous body having a large number of holes was used. In addition, as the 1st thermal storage body 71, the ceramic honeycomb formed by forming many grid | lattice-like cells can also be used. In addition, it is preferable to use the first heat storage body 71 having a large surface area per unit volume and a low pressure loss.

  As shown in FIG. 1, the second heat storage body 72 of this example is configured by arranging a large number of ceramic balls, which are ball-shaped ceramics. The second heat storage body 72 is disposed so as to fill a space in the body passage 41 of the burner body 4. In addition, as the 2nd thermal storage body 72, a ceramic foam or a ceramic honeycomb can also be used. Moreover, since the temperature of the exhaust gas which contacts the 2nd thermal storage body 72 is not so high, a metal thing can also be used.

As shown in FIG. 4, the burner gun 6 of this example is configured by inserting a fuel pipe 62 through which the fuel gas F is ejected into a cooling air pipe 61 through which the cooling air A <b> 3 is ejected. The gas burner 3 of this example is configured to perform flame holding by burning a part of the fuel gas F ejected from the fuel pipe 62 and the cooling air A3 ejected from the cooling air pipe 61. A spark rod 65 for igniting combustion is inserted and disposed in the cooling air pipe 61.
A gas nozzle 63 is formed at the tip of the fuel pipe 62, and a fuel injection hole 631 for injecting the fuel gas F into the combustion cylinder 5 is formed in the gas nozzle 63.

  In the radiant tube burner 1 of the present example, an outer passage 51 formed between the radiant tube 2 and the combustion cylinder 5 with a body passage 41 in the burner body 4 disposed on the furnace wall outer surface 801 of the heat treatment furnace 8; It communicates with an inner passage 52 formed between the combustion cylinder 5 and the burner gun 6. The first heat storage body 71 is disposed in the inner passage 52 and the second heat storage body 72 is disposed in the body passage 41.

  Then, combustion is performed by one gas burner 3, and exhaust heat of exhaust gas after passing through the radiant tube 2 is recovered by the first heat storage body 71 and the second heat storage body 72 in the other gas burner 3. At this time, the exhaust gas comes into contact with the first heat storage body 71 in the inner passage 52, whereby first-stage exhaust heat recovery is performed, and the temperature of the exhaust gas decreases. As a result, the temperature decreases around the attachment portion 31 of the gas burner 3 to the furnace wall outer surface 801 (radiant tube flange 21, rear end of the combustion cylinder 5, combustion cylinder support flange 53, partition plate 43, etc.). The exhaust gas in the state can be passed. Therefore, the structure around the mounting portion 31 of the gas burner 3 does not need to be configured using a refractory material such as ceramics, and can be configured using metal.

Further, the exhaust gas after the first stage exhaust heat recovery is brought into contact with the second heat storage body 72 in the burner body 4 allows the second stage exhaust heat recovery to be performed, and the temperature of the exhaust gas. Is further reduced. Thereby, exhaust gas exhaust heat recovery can be sufficiently performed.
Further, in this example, the heat storage capacity is increased without increasing the size of the gas burner 3 by arranging the first heat storage body 71 using the inner passage 52 between the combustion cylinder 5 and the burner gun 6. Can be increased.

  Further, when combustion is performed in the gas burner 3 on the side where the exhaust heat is recovered, the fuel gas F ejected from the fuel ejection hole 631 in the gas nozzle 63 and the cooling gas ejected through the cooling air pipe 61 are used. The air A3 is combusted to form a flame holding flame. At this time, the cooling air A3 can suppress the gas nozzle 63 and the tip of the cooling air pipe 61 from becoming high temperature, and these can be protected from heat.

Further, the air flowing into the body passage 41 of the burner body 4 from the air inlet 412 comes into contact with the second heat storage body 72 and is heated. A part of the heated air passes through the plurality of communication ports 431 formed in the partition plate 43 and comes into contact with the first heat storage body 71 in the inner passage 52 to be further heated. Air A1.
The main air A1 is mixed with the fuel gas F ejected from the fuel ejection hole 631 of the gas nozzle 63, and the air-fuel mixture is ignited by the flame holding flame, whereby the first stage combustion is performed. As a result, a flame is formed from the combustion cylinder 5 toward the radiant tube 2 due to the first stage fuel-rich incomplete combustion.

The remaining air heated in contact with the second heat storage body 72 passes through the air passage gap 54 formed between the combustion cylinder 5 and the combustion cylinder support flange 51 and then the outer passage 51. It passes through the inside and becomes sub air A2. The sub-air A2 is supplied to the flame, whereby the second stage combustion is performed. Thereby, in the radiant tube 2, the unburned part in the first stage combustion can be burned completely.
Thus, the amount of NOx generated can be reduced by performing two-stage combustion to suppress rapid combustion.

  Therefore, according to the radiant tube burner 1 of this example, the periphery of the attachment portion 31 of the gas burner 3 can be configured using metal or the like, and the heat storage bodies 71 and 72 are not increased without increasing the size of the gas burner 3. It is possible to increase the heat storage capacity due to, and to reduce the amount of NOx produced by combustion.

  In this example, it is considered that the temperature of the sub air A2 used for the second stage combustion is heated to the same or higher temperature than the temperature of the main air A1 used for the first stage combustion. More specifically, the sub air A <b> 2 used for the second stage combustion is heated by the combustion cylinder 5 and the radiant tube 2 when passing through the outer passage 51, so that the temperature is higher than the temperature in the heat treatment furnace 8. It is considered that the temperature is higher by 30 to 50 ° C. and is 60 to 80 ° C. higher than the temperature of the main air A1 used for the first stage combustion.

(Example 2)
In this example, as shown in FIG. 5, a first combustion cylinder portion 56 that forms the inner passage 52 between the burner gun 6 and a second combustion cylinder portion that is connected to the tip of the first combustion cylinder portion 56. 57 is an example in which the above-described combustion cylinder 5 is configured. The first heat storage body 71 is disposed between the first combustion cylinder portion 56 and the burner gun 6. Moreover, the 1st combustion cylinder part 56 is comprised from the metal, and the 2nd combustion cylinder part 57 is comprised from the ceramics.

  In addition, a flange portion 571 protruding outward in the radial direction is formed at the rear end portion of the second combustion cylinder portion 57. The second combustion cylinder portion 57 is inserted into the front end opening 561 of the first combustion cylinder portion 56 and the first combustion cylinder portion 57 is prevented from coming off by a pin (such as a screw) 572. The cylinder portion 56 is connected. Further, the first heat storage body 71 is prevented from coming off by the flange portion 571 of the second combustion cylinder portion 57.

In this example, since the first combustion cylinder portion 56 is made of metal, it is easy to form or process a flange portion protruding radially outward at the rear end portion of the combustion cylinder 5. become. In addition, by configuring the second combustion cylinder portion 57 from ceramics, it is possible to improve the heat resistance of the tip side portion of the combustion cylinder 5 that comes into contact with the higher temperature exhaust gas or the combustion flame.
Also in this example, other configurations are the same as those of the first embodiment, and the same effects as those of the first embodiment can be obtained.

Cross-sectional explanatory drawing which shows the periphery of the gas burner of a radiant tube burner in an Example. Sectional explanatory drawing which shows the periphery of the attachment part of a gas burner in an Example. Cross-sectional explanatory drawing which shows the periphery of the attachment part of a gas burner in the Example seen from the axial direction. Cross-sectional explanatory drawing which shows the periphery of the gas nozzle of a burner gun in an Example. Cross-sectional explanatory drawing which shows the periphery of a gas burner in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiant tube burner 2 Radiant tube 3 Gas burner 31 Mounting part 4 Burner body 401 Opening part 41 Body passage 42 Body mounting flange 5 Combustion cylinder 51 Outer passage 52 Inner passage 56 First combustion cylinder part 57 Second combustion cylinder part 6 Burner gun 61 Cooling Air pipe 62 Fuel pipe 63 Gas nozzle 71 First heat accumulator 72 Second heat accumulator 8 Heat treatment furnace 801 Furnace wall outer surface 802 Furnace wall inner surface F Fuel gas A1 Main air A2 Sub air A3 Cooling air

Claims (3)

A radiant tube disposed in a heat treatment furnace, and a pair of gas burners disposed at both ends of the radiant tube and alternately forming a combustion flame in the radiant tube, the heat treatment by radiant heat from the radiant tube In a radiant tube burner configured to heat the furnace interior,
The gas burner includes a burner body disposed on an outer surface of the furnace wall of the heat treatment furnace, a combustion cylinder inserted and disposed in the radiant tube from an opening on the furnace wall inner surface side of the burner body, and the combustion cylinder from the burner body. With a burner gun inserted and placed inside,
An outer passage communicating with the burner body is formed between the radiant tube and the combustion cylinder, and an inner passage communicating with the burner body is formed between the combustion cylinder and the burner gun. Formed,
A first heat storage body for recovering exhaust heat is disposed in the inner passage, and a second heat storage body for recovering exhaust heat is disposed in the burner body,
After the fuel gas ejected from the burner gun comes into contact with the second heat storage body in the burner body, the first stage combustion is performed using the main air in contact with the first heat storage body in the inner passage. In addition, the radiant tube burner is configured to perform second-stage combustion using the sub air that has passed through the outer passage after contacting the second heat storage body in the burner body. The burner gun according to claim 1, wherein the burner gun is configured by inserting a fuel pipe through which the fuel gas is ejected and inserted into a cooling air pipe through which the cooling air is ejected.
A radiant tube burner configured to perform flame holding by burning a part of the fuel gas ejected from the fuel tube and the cooling air ejected from the cooling air tube. 3. The combustion cylinder according to claim 1, wherein the combustion cylinder includes a first combustion cylinder part that forms the inner passage with the burner gun, and a second combustion cylinder part that is connected to a tip part of the first combustion cylinder part. Become
The radiant tube burner is characterized in that the first combustion cylinder part is made of metal, and the second combustion cylinder part is made of ceramics.

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