JP2768902B2 - Zonal flame burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip flame burner used for an industrial heating furnace and the like, and more particularly to a strip flame burner (hereinafter, referred to as a slit burner) having a built-in recuperator and having a low NOx function. Things.

[0002]

2. Description of the Related Art Conventionally, a slit burner is often used in place of a circular flame burner in order to make a combustion chamber in a furnace compact and to make the temperature distribution in the room uniform. And
FIG. 4 shows a conventional slit burner, and the burner body 1 of this slit burner generally includes a burner tile 2 and a burner case 3 provided on a side portion of the burner tile 2. On the front side surface 4 of the burner tile 2 facing the inside of the furnace, an elongated rectangular opening 5 is provided. A space having the same width as the opening 5 and gradually decreasing in width in the height direction toward the inside is formed inside the burner tile from the opening 5. A combustion chamber 6, a throat portion 7, and a mixing zone 8 are sequentially formed.

On the other hand, a combustion air chamber 9 formed of a rectangular parallelepiped space is formed inside the burner case 3, and an air nozzle having substantially the same width as the opening 5 is provided on a side wall of the combustion air chamber 9. 10 is provided projecting forward. The air nozzle 10 is fitted into an air nozzle insertion portion 15 formed on the rear side surface of the burner tile 2, and an opening formed at the tip of the air nozzle 10 is connected to the rear of the mixing zone 8. I have. The air nozzle 10
At a position corresponding to the opening of the tip of the air nozzle 10, a fuel nozzle 11 having a plurality of fuel gas injection ports arranged linearly in the horizontal direction along the opening at the tip thereof. And a fuel pipe 12 inserted through the fuel nozzle 11 through the rear wall of the burner case 3 and inserted into the combustion air chamber 9.
Is connected. A combustion air supply port 13 is provided below the combustion air chamber 9, and an air pipe 14 is connected to the combustion air supply port 13.

In the conventional slit burner having the above structure, the fuel gas 20 sent from the fuel gas supply source 19 is supplied to the fuel nozzle 11 through the fuel pipe 12 and injected from the fuel gas injection port at the tip. You. on the other hand,
Combustion air 22 sent from combustion air supply source 21
Is preheated by high-temperature exhaust gas 24 generated by combustion in the recuperator 23, and then supplied to the combustion air chamber 9 via the air pipe 14. Then, the combustion air 2
2 is injected into the mixing zone 8 from an opening at the tip of the air nozzle 10 through a combustion air passage formed between the air nozzle 10 and the fuel nozzle 11. Then, the fuel gas 20 and the combustion air 22 are rapidly mixed in the mixing zone 8 and then burnt in the combustion chamber 6 to form a strip flame in the furnace from the opening 5 of the burner tile 2.

[0005]

As described above, in the conventional slit burner, when preheated air is used due to its structure, the combustion air is sent to the burner after passing through a separately provided recuperator. That is, the combustion air 22
Is preheated by a recuperator 23 provided outside the burner main body 1, and then supplied to the burner main body 1 through the air pipe 14.
There is a problem that the heat efficiency is lowered and the equipment cost is increased because the air pipe 14 needs to be a high-temperature air pipe. The conventional slit burner is N
There was also a problem that no Ox reduction measures were taken.

In order to solve the above-mentioned problems, the present invention provides a slit burner having a built-in recuperator for preheating combustion air in a burner body and having an exhaust gas circulating mechanism for reducing NOx. For the purpose of providing.

[0007]

In order to achieve the above object, a slit burner according to the present invention comprises a burner main body, a fuel gas nozzle having a plurality of linearly arranged injection ports, A combustion air nozzle having a slit-shaped nozzle portion is provided, and a band-shaped flame burner that mixes and burns fuel gas and combustion air respectively injected from the fuel gas nozzle and the combustion air nozzle, wherein the burner body is A fuel gas supply port communicating with the fuel gas nozzle, a combustion air supply port, a plurality of combustion air passages connecting the combustion air supply port with the combustion air nozzle, an exhaust gas suction port, and an exhaust gas discharge port. A plurality of exhaust gas passages that connect the exhaust gas suction port and the exhaust gas exhaust port and that are in contact with the combustion air passage; An exhaust gas circulation passage communicating with the injection port near the use air nozzles, and exhaust gas circulation amount control valve for adjusting the amount of exhaust gas flowing through the exhaust gas circulation passage, in which the provided.

[0008]

The combustion air supplied from the combustion air supply port into the burner body passes through the plurality of combustion air passages, and flows through a plurality of exhaust gas passages provided in contact with the combustion air passages. Exhaust heat is efficiently recovered from the exhaust gas and preheated. Then, the combustion air is injected from the tip of the combustion air nozzle, rapidly mixed with the fuel gas injected from the fuel gas nozzle, and then burns in a region near the injection port of the combustion air nozzle. Further, a part of the exhaust gas is injected into the region near the injection port of the combustion air nozzle through the exhaust gas circulation passage, whereby the temperature of the burning flame is reduced and the generation of thermal NOx is suppressed. Further, by controlling the amount of exhaust gas to be injected into the region near the injection port of the combustion air nozzle by the exhaust gas circulation amount control valve, the combustion stability as well as the low NOx property are ensured.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a vertical section of the slit burner of this embodiment, and FIG. 2 shows a II-II section in the slit burner vertical section shown in FIG.

The burner body 1 of the slit burner shown in FIG.
Is composed of a burner tile 2 and a burner case 3 fixed to the side of the burner tile 2. At the center of the front side surface 4 of the burner tile 2 facing the inside of the furnace, a horizontally long opening 5 is formed, and a combustion chamber 6 having a rectangular cross section is formed inside the burner tile 2 from the opening 5. Have been. Behind the combustion chamber 6, a mixing zone 8 formed of a space whose height in the height direction is smaller than that of the combustion chamber 6 is provided in communication with the combustion chamber 6. On the other hand, the lower part of the front side face 4 of the burner tile 2 has an exhaust gas suction port 3.
0 is formed, and an exhaust gas suction passage 31 is formed inside the burner tile 2 from the exhaust gas suction port 30.

The burner case 3 is formed of a box having an open front, and a combustion air supply port 13 is provided at a lower portion of the rear side wall 7 of the burner case 3. An exhaust duct 32 is connected to the upper surface of the burner case 3.
Inside the exhaust duct 32, an ejector nozzle 35 for ejecting ejector air 33 for sucking and exhausting exhaust gas from the furnace is provided upward.

A fuel pipe 12 is provided horizontally at the center of the inside of the burner case 3. This fuel pipe 12
As shown in FIG. 3, it is composed of two pipes formed in an L shape, and one end thereof is connected to the fuel supply port 15.
The other end of the fuel pipe 12 is connected to a hollow manifold portion 16 having both ends sealed, and a fuel gas in which a plurality of fuel gas injection ports 18 are linearly arranged at the front end of the manifold portion. A nozzle 11 is provided. The fuel supply port 15 has a rear end projecting from the rear wall 7 of the burner case 3 and connected to a fuel gas supply source 19.

The recuperator 23 built in the burner case 3 includes a partition wall 40, upper and lower bulging portions 41 and 42,
The fuel pipe 1 comprises upper and lower partition plates 43 and 44.
The air nozzle 10 which forms a combustion air passage outside of 2 also forms part of the recuperator 23. The partition wall 40 is provided at a predetermined distance from the rear wall 7 of the burner case 3, and a combustion air chamber 9 is formed between the partition wall 40 and the rear wall 7.

The air nozzle 10 is provided so as to surround the fuel pipe 12 and the manifold section 16, and the rear end thereof is connected to the combustion air chamber 9 to form a combustion air passage 63 around the fuel pipe 12. doing. A tip of the air nozzle 10 surrounding the manifold 16 is formed with a slit-shaped nozzle 14 narrowed down in a tapered shape, and is located in the mixing zone 8 in front of the fuel nozzle 11. The upper and lower bulging portions 41 and 42
Are provided at positions vertically symmetrical with respect to the air nozzle 10 so as to protrude from the partition wall 40. The above-mentioned partition plates 43 and 44 are inserted respectively. These partition plates 43, 44 are provided at a predetermined interval between the front ends thereof and the inner peripheral tips of the upper and lower bulging portions 41, 42, and the side ends of the partition plates 43, 44 are provided. Has a substantially oval cross section, as shown in FIG.
The inner peripheral surfaces of the lower bulging portions 41 and 42 are in contact without any gap. As a result, the U-shaped combustion air passages 60, 6 are formed inside the upper and lower bulging portions 41, 42 by the partition plates 43, 44.
1, 64, 65 are formed.

On the other hand, exhaust gas passages 66, 67, 68, 69, 70, 71 are formed between the air nozzle 10 and the inner surfaces of the burner tiles 2 outside the upper and lower bulging portions 41, 42. I have. As shown in FIG. 2, the outer passage 68 of the lower bulging portion 42 and the upper bulging portion 4
A passage 45 communicating with the first outer passage 69 is formed, and the passage 45 connects the exhaust gas suction port 30 and the exhaust duct 32.

Exhaust gas circulation passages 50 and 51 are formed between the nozzle portion 14 at the tip of the air nozzle 10 and the burner tile 2, and exhaust gas passages 68 and 69 located above and below the air nozzle 10 communicate with the mixing zone 8. Have been. The exhaust gas passages 68, 6 of the exhaust gas circulation passages 50, 51
Exhaust gas circulating flow control valves 52, 53 having a sufficient area to close the exhaust gas circulating passages 50, 51 are provided at the inlet on the 9th side, and rod members 54, 55 connected to the exhaust gas circulating flow control valves 52, 53 are provided. Is extended to the rear of the burner case 3 through the partition wall 40 and the rear wall 7, and ring-shaped handles 56, 57 are provided at the end thereof. These handles 56, 57
Forward or backward, the exhaust gas circulation amount control valve 52,
By opening and closing the inlets of the exhaust gas circulation passages 50 and 51 at 53, the amount of exhaust gas circulated to the combustion chamber 6 can be adjusted.

Next, the combustion operation of the slit burner having the above configuration will be described. The fuel gas 20 sent from the fuel gas supply source 19 is injected from the fuel gas injection port 18 at the tip of the fuel nozzle 11 through the fuel pipe 12 and the manifold 16. Further, a combustion air supply source 2
1 is supplied from the combustion air supply port 13 and the combustion air 22 is supplied from the combustion air chamber 9 to the lower bulging portion 42.
Inner passages 60 and 61 and the inner passage 6 of the air nozzle 10
3 and is ejected from the tip of the nozzle portion 14. on the other hand,
Upper part 9 'of combustion air chamber 9 via a bypass (not shown)
The same applies to the combustion air 22 circulated to the air nozzle 10, after passing through the internal passages 64 and 65 of the upper bulging portion 41 and joining the combustion air 22 having passed through the lower bulging portion 42 at the rear inside the air nozzle 10. , From the nozzle portion 14. Therefore, the fuel gas 2 injected from the fuel nozzle 11
0 is the combustion air 22 in the mixing zone 8.
After rapid mixing with the burner tile 2
A belt-like flame is formed in the furnace from the opening 5.

On the other hand, high-temperature exhaust gas generated by combustion is supplied to the suction air 33 sent from the suction air supply source 34.
Is sucked from the exhaust gas suction port 30 by a suction effect generated by being ejected upward from the ejector nozzle 35. After that, the exhaust gas is discharged into the exhaust gas suction passage 31 and the lower bulging portion 4.
2 outer passages 66, 67, 68, passage 45, upper bulging portion 41
The air is discharged from the exhaust duct 32 through the outer passages 69, 70, 71. In the process, high-temperature exhaust gas is supplied to the air nozzle 10 functioning as a recuperator and the upper and lower bulging portions 4.
1,42, the combustion air 22 passing inside these
Is heated and exhausted as low-temperature exhaust gas.

As described above, in the slit burner of the present embodiment, the recuperator 23 for preheating the combustion air 22 is built in the burner main body 1, so that it is necessary for the conventional slit burner separately provided with a recuperator. External high-temperature air piping is not required, and equipment costs can be reduced. In addition, since heat radiation loss from the high-temperature air pipe as in the related art is eliminated, the thermal efficiency can be improved.

Further, the recuperator 23 built in the burner main body 1 has a plurality of passages capable of exchanging heat between the combustion air 22 as the heat receiving fluid and the exhaust gas as the heat radiating fluid, so that a high efficiency is achieved. Heat exchange becomes possible.

Further, since the exhaust gas passage and the exhaust duct 32 are provided inside the burner main body 1, there is no need to provide a high temperature exhaust flue (chimney) in the furnace main body, and the structure of the furnace can be simplified. it can.

On the other hand, a part of the exhaust gas flowing through the exhaust gas passages 68 and 69 formed between the air nozzle 10 and the upper and lower bulging portions 41 and 42 is partially discharged from the nozzle portion 14 at the tip of the air nozzle 10.
The fuel gas 20 and the combustion air 22 are injected into the combustion chamber 8 through the exhaust gas circulation passages 50 and 51. As a result, the exhaust gas can be mixed with the burning flame to lower the flame temperature and suppress the generation of thermal NOx. The amount of exhaust gas circulating in the combustion chamber 8 changes the opening degree of the inlet of the exhaust gas circulation passages 50 and 51 by moving the handles 56 and 57 connected to the exhaust gas circulation amount control valves 52 and 53 in the front-back direction. Accordingly, the low NOx property and the combustion stability can be easily ensured even when the exhaust gas circulation amount changes due to another condition change.

[0023]

As is apparent from the above description, according to the belt-shaped flame burner of the present invention, the high-temperature air piping required for the conventional band-shaped flame burner separately provided with a recuperator becomes unnecessary and the equipment cost is reduced. At the same time, since the heat loss from the high-temperature air pipe as in the related art is eliminated, the thermal efficiency can be improved.

The recuperator built in the burner main body is formed with a combustion air passage and an exhaust gas passage composed of a plurality of passages, respectively, so that high-efficiency heat exchange is possible.

Further, the exhaust gas circulation passage and the exhaust gas circulation amount control valve are provided, so that the amount of exhaust gas circulating in the combustion chamber can be adjusted arbitrarily. Low NOx property and combustion stability can be easily ensured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a strip-shaped flame burner of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.
It is sectional drawing.

FIG. 3 is an enlarged perspective view of a fuel pipe, a fuel nozzle, and an air nozzle portion.

FIG. 4 is a longitudinal sectional view of a conventional strip flame burner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Burner main body, 2 ... Burner tile, 3 ... Burner case, 6 ... Combustion chamber, 8 ... Mixing zone, 10 ... Air nozzle, 11 ... Fuel nozzle, 12 ... Fuel pipe, 13 ... Combustion air supply port, 15 ... Fuel gas supply port, 30: Exhaust gas suction port, 32: Exhaust duct, 50, 51: Exhaust gas circulation passage, 52, 53: Exhaust gas circulation amount control valve

Claims (1)

(57) [Claims] 1. A fuel gas nozzle having a plurality of injection ports arranged linearly in a burner main body, and a combustion air nozzle provided on the fuel gas nozzle and having a slit-shaped nozzle portion at a tip thereof. And a band-shaped flame burner that mixes and burns fuel gas and combustion air injected from a combustion air nozzle, respectively, wherein the burner body has a fuel gas supply port communicating with the fuel gas nozzle, a combustion air supply port, A plurality of combustion air passages connecting the combustion air supply port and the combustion air nozzle; an exhaust gas suction port; an exhaust gas discharge port; and the combustion air passage connecting the exhaust gas suction port and the exhaust gas discharge port. A plurality of exhaust gas passages in contact with the exhaust gas passage; an exhaust gas circulation passage branched from the exhaust gas passage and leading to the vicinity of the injection port of the combustion air nozzle; Strip flame burner, characterized by comprising the exhaust gas circulation amount control valve for adjusting the amount of exhaust gas flowing through the passage, the.