JPH0774686B2 - Fuel nozzle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel nozzle for injecting fuel gas in a burner.

[0002]

2. Description of the Related Art Conventionally, a flame shape variable burner shown in FIGS. 4 and 5 is known. Of these burners, the burner 30 shown in FIG. 4 is composed of a cylindrical fuel nozzle 32 connected to a fuel supply pipe 31 and an air nozzle 33 surrounding the fuel nozzle 32. The air nozzle 33 is the inner first air. It is composed of a nozzle portion 34 and a second air nozzle portion 35 located outside the first air nozzle portion 34. These air nozzle portions 34, 35 are separated by a partition wall 36, and a first air nozzle portion is divided by a distribution valve 37. The amount of air supplied to the first air nozzle unit 34 and the second air nozzle unit 35 can be adjusted appropriately.

In the burner 30, the fuel gas 38 supplied from the fuel supply pipe 31 is injected from the fuel nozzle 32. Meanwhile, the combustion air 39 supplied to the air nozzle 33
Are distributed to the first air nozzle section 34 and the second air nozzle section 35 according to the opening degree of the distribution valve 37. Then, the fuel gas 38 injected from the fuel nozzle 32 is the combustion air (primary air) 391 first injected from the first air nozzle unit 34.
Is mixed and diffused and burned, and mixed and diffused and burned with combustion air (secondary air) 392 injected from the second air nozzle portion 35 on the tip side, that is, on the downstream side of the flame (not shown). Therefore, if the amount of the primary air 391 is increased by the distribution valve 37, the flame becomes a short flame, and if the amount of the secondary air 392 is increased, the flame becomes a long flame.

Next, the burner 40 shown in FIG.
1 has a double structure in which a first fuel nozzle portion 42 is formed inside and a second fuel nozzle portion 43 is formed outside, and the second fuel nozzle portion 4 is formed.
The injection holes 44 of No. 3 are oriented obliquely outward so that the amount of fuel supplied to these nozzles 42, 43 can be adjusted by the distribution valve 45. Further, the air nozzle 46 surrounds the fuel nozzle 41, and the first air nozzle portion 4 inside
7 and a second air nozzle portion 48 located outside the first air nozzle portion 47.

In the burner 40, the fuel gas 50 supplied to the fuel supply passage 49 is distributed to the first fuel nozzle portion 42 and the second fuel nozzle portion 43 according to the opening degree of the distribution valve 45, and the first fuel is supplied. Fuel gas 50 injected from the nozzle 42
1 is injected straight in the axial direction, and the second fuel nozzle portion 43
The injected fuel gas 502 is injected obliquely outward. On the other hand, the air 51 supplied to the air nozzle 46
Is ejected from the first air nozzle portion 47 and the second air nozzle portion 48. The fuel gas 502 injected from the second fuel nozzle section 43 is supplied to the first and second air nozzle sections 47 and 48.
The mixed and diffused combustion is performed near the air 51 and the burner 40, which are further injected, and the fuel gas 501 injected from the first fuel nozzle portion 42 is combusted on the tip side of the flame. Therefore, if the fuel gas 501 injected from the first fuel nozzle portion 42 is increased, a long flame having a small diameter is produced, and if the fuel gas 502 injected from the second fuel nozzle portion 43 is increased, a short flame having a large diameter is produced. Become.

[0006]

However, in the former burner 30, although the structure of the fuel nozzle 32 is simple, the inside of the air nozzle 33 is divided into the first air nozzle portion 34 and the second air nozzle portion 35. Since the partition wall 36 is required, there is a problem that the structure becomes complicated and the manufacturing cost becomes high. On the other hand, in the latter nozzle, a partition for dividing the air nozzle is not necessary, but one fuel nozzle portion is closed by the distribution valve 45 and the fuel gas 50 is supplied only from the other fuel nozzle portion.
Is injected, there is a problem that the preheating temperature of the combustion air 51 (500 ° C. or higher) or the radiant heat in the furnace causes carbonization of the fuel gas remaining in the closed fuel nozzle portion and burnout of the burner 40. .

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a fuel nozzle has an annular front wall formed by projecting inward the front and rear portions of a tubular body. An outer cylinder provided with a rear wall and a plurality of first fuel injection holes in the front wall, a fuel supply passage for supplying fuel gas to the outer cylinder, and an outer cylinder housed coaxially therewith. A plurality of inner shafts each having a rear end fixed to the rear wall and a fuel flow path formed between the front end and the front wall, and a shaft inserted into the inner cylinder through a seal member so as to move back and forth. A sleeve extending toward the front end portion of the inner cylinder via a flange having a second fuel injection hole, the sleeve protruding outward from the inner cylinder via the fuel flow path, and the first fuel injection And a switching valve provided with a seal portion facing the hole.

It is preferable that the first fuel injection hole is formed obliquely outward and the second fuel injection hole is formed in the axial direction of the shaft. Further, the diameter of the first fuel injection hole may be different from the diameter of the second fuel injection hole.

[0009]

In the fuel nozzle having the above structure, the sleeve and the seal portion move back and forth in the fuel flow passage by advancing and retracting the shaft. At the most advanced position of the shaft, the sleeve separates from the front end of the inner cylinder to open the fuel flow path, and the seal portion seals the first fuel injection hole on the front wall of the outer cylinder. Therefore, the fuel gas supplied from the fuel supply pipe is injected from the second combustion fuel injection hole through the fuel flow path. At the position where the shaft is most retracted, the sleeve contacts the front end portion of the inner cylinder to close the fuel flow path, and the seal portion opens the first fuel injection hole. Therefore, the fuel gas supplied from the fuel gas supply pipe is injected from the first fuel injection hole. When the shaft is located between the most advanced position and the most retracted position, both the fuel flow path and the first fuel injection hole are opened, and the amount of fuel corresponding to the opening degree of the fuel flow path is reduced to the first fuel injection hole and the first fuel injection hole. 2 Fuel is injected from the fuel injection hole.

When the first fuel injection hole is formed obliquely outward and the second fuel injection hole is formed in the axial direction of the shaft, the fuel gas injected from the first fuel injection hole is near the nozzle. And the fuel gas injected from the second fuel injection hole advances straight along the shaft axial direction. Therefore, if the combustion air nozzles are arranged around the fuel nozzles, the fuel and combustion air injected from these nozzles undergo mixed diffusion combustion in the vicinity of the nozzles. And the second
When the fuel injection hole is closed, the fuel gas obliquely injected from the first fuel injection hole is mixed and diffused with the fuel air in the vicinity of the nozzle, and the flame becomes a short flame having a large diameter. On the other hand, when the first fuel injection hole is closed, the fuel injected from the second fuel injection hole advances straight in the axial direction of the shaft and is mixed and diffused and burned at the tip end thereof, so that the flame is a long flame with a small diameter. Become.

If the diameters of the first fuel injection hole and the second fuel injection hole are different, a large diameter first fuel injection hole and a small diameter second fuel injection are used depending on the properties of the fuel, for example, the amount of heat generation and the pressure. The holes can be appropriately used.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show a fuel nozzle 1 according to the present invention, in which an outer peripheral wall 3 is protruded inwardly to form a ring-shaped front wall 4 and a rear wall 5 at a front portion and a rear portion of an outer cylinder 2 made of a cylindrical body. A front opening 6 and a rear opening 7
Is formed, and first fuel injection holes 8 that extend obliquely outward are formed in the front wall 4 at predetermined intervals. A fuel gas supply pipe 10 is connected to the outer peripheral portion of the outer cylinder 2.

The inner cylinder 11 is a cylindrical body having a ring-shaped stopper wall 12 projecting outward at the front end thereof, and is housed inside the outer cylinder 2 coaxially therewith, and the rear end thereof is at the rear wall. The fuel flow passage 13 is fixed to the inner wall 5 and has a predetermined length between the stopper wall 12 and the front wall 4.

The switching valve 14 includes a shaft 15, a ring-shaped flange portion 16 having a tip end portion of the shaft 15 protruding outwardly and having an outer diameter substantially the same as that of the opening portion 6, and the flange portion 16. 1 with the outer peripheral edge of the
7 and a ring-shaped seal portion 18 having an outer peripheral surface of the sleeve 17 protruding outwardly.
The second fuel injection hole 1 has a diameter larger than that of the first fuel injection hole 8.
9 are formed at predetermined intervals. This switching valve 14
Through the opening 7 in the rear wall 5 to the inner cylinder 11 through the shaft 14
, The rear end of the sleeve 17 is opposed to the stopper wall 12 provided at the front end of the inner cylinder 11, the seal portion 18 is positioned in the fuel flow path 13, and the rear end of the sleeve 17 is inserted as shown in FIG. Is abutted against the stopper wall 12, and as shown in FIG. 2, the seal portion 18 can move forward and backward between a forward position where the first fuel injection hole 8 is closed. A seal member 9 seals between the shaft 15 and the opening 7. Further, a seal member or a bearing member may be appropriately provided between the shaft 15 and the inner cylinder 11.

In the fuel nozzle 1 having the above structure, the switching valve 14
1 in the retracted position shown in FIG. 1, the seal portion 18 is separated from the front wall 4, and the rear end of the sleeve 17 contacts the stopper wall 12 to close the fuel flow path 13. Therefore, the fuel gas 20 supplied from the fuel gas supply pipe 10 moves forward in the annular space formed between the outer cylinder 2 and the inner cylinder 11, passes through the outside of the stopper wall 18, and the first fuel injection is performed. Hole 8
It is ejected more obliquely outward. Further, when the switching valve 14 is at the forward position shown in FIG.
2, the fuel flow path 13 is opened, and the seal portion 18 abuts the rear surface of the front wall 4 to close the first fuel injection hole 8. Therefore, the supplied fuel gas 20 is conveyed to the inner space of the sleeve 17 via the fuel flow path 13, and is injected straight in the axial direction via the second fuel injection hole 19. Further, when the switching valve 14 is located between the forward position and the rear end position, both the fuel passage 13 and the first fuel injection hole 8 are opened, and the first fuel injection hole is opened according to the opening degree of the fuel passage 13. 8 and the second fuel injection hole 19 inject fuel gas 20.

Next, a burner incorporating the fuel nozzle 1 will be described with reference to FIG. This burner 21
Has the fuel nozzle 1 in the center of the main body 22, and an air nozzle 23 is arranged around the fuel nozzle 1. A first air injection hole 24 is formed around the fuel nozzle 1 at the front of the air nozzle 23, and a second air injection hole 24 is formed outside the first air injection hole 24 along the circumferential direction.
Air injection holes 25 are provided at predetermined intervals, and the main body 22
An air supply pipe 26 is connected to the rear part of the rear part.

In the burner 21 having the above structure, the air supply pipe 2
The combustion air 27 supplied to the air nozzle 23 from No. 6 is the first
The fuel gas 20 injected from the air injection hole 24 and the second air injection hole 25 is mixed with the fuel gas 20 injected from the fuel nozzle 1 and burned. Then, when the switching valve 14 of the fuel nozzle 1 is at the forward position, the fuel gas 20 axially injected from the second fuel injection hole 19 of the fuel nozzle 1 is first injected from the first air injection hole 24 to be burned. The air 27 is diffusively mixed and burned with the combustion air 27, which is diffused and mixed with the combustion air 27 injected from the second air injection hole 25 on the flame tip side, and the flame becomes a long flame 28 having a small diameter. On the other hand, when the switching valve 14 is in the retracted position, the fuel gas 20 injected obliquely outward from the first fuel injection hole 8 of the fuel nozzle 1 receives the first air injection hole 24.
While being diffusively mixed with the combustion air 27 injected further, it spreads outward and is diffusively mixed with the air 27 injected from the second air injection holes 25 flowing around it and burned. Therefore, since the fuel gas 20 and the combustion air 27 are mixed and burned in the vicinity of the burner 21, the flame becomes a short flame 29 having a large diameter. Further, when the switching valve 14 is located between the forward position and the backward position, the fuel gas 20 is injected from the first fuel injection hole 8 and the second fuel injection hole 19, and the respective injection holes 8,
The flame shape is adjusted according to the amount of fuel gas 20 injected from 19.

In the above embodiment, the second fuel injection hole 1
Although 9 has a larger diameter than the first fuel injection hole 8, the present invention is not limited to this, and the first fuel injection hole 8 may have a larger diameter than the second fuel injection hole 19, or both may have the same diameter. Good. Further, depending on the type of fuel, the first fuel injection hole 8 and the second fuel injection hole 19
You may use differently. In this case, a large-diameter fuel injection hole and a small-diameter fuel injection hole are appropriately selected according to the properties of the fuel, such as the amount of heat generation and the pressure.

[0019]

As is apparent from the above description, according to the fuel nozzle of the present invention, the burner using this fuel nozzle can change the flame shape without dividing the air nozzle by the partition wall. , The structure of the burner itself becomes simple. Further, since the seal portion and the sleeve are provided in the front portion of the switching valve to open and close the first fuel injection hole and the fuel flow path, respectively, even when only one fuel injection hole is used, the other Fuel gas does not remain in the fuel flow path, and there is no problem due to carbonization of this residual fuel. Further, different kinds of fuel gas can be burned by making the diameters of the first fuel injection hole and the second fuel injection hole different.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fuel nozzle with a switching valve in an advanced position.

FIG. 2 is a cross-sectional view of a fuel nozzle with a switching valve in a retracted position.

FIG. 3 is a cross-sectional view of a burner including a fuel nozzle according to the present invention.

FIG. 4 is a sectional view of a conventional burner.

FIG. 5 is a cross-sectional view of another conventional burner.

[Explanation of symbols]

1 ... Fuel nozzle, 2 ... Outer cylinder, 4 ... Front wall, 5 ... Rear wall, 6,
7 ... Opening part, 8 ... First fuel injection hole, 10 ... Fuel supply pipe,
11 ... Inner cylinder, 12 ... Stopper wall, 13 ... Fuel flow path, 14
... Switching valve, 15 ... Shaft, 16 ... Flange section, 17 ...
Sleeve, 18 ... Sealing portion, 19 ... Second fuel injection hole, 2
0 ... Fuel gas.

Claims (3)

[Claims] 1. An outer cylinder in which a front portion and a rear portion of a tubular body are respectively provided to project inward to provide an annular front wall and a rear wall, and the front wall is provided with a plurality of first fuel injection holes. A fuel supply path for supplying a fuel gas to the outer cylinder, and a coaxially housed inside the outer cylinder, the rear end of which is fixed to the rear wall, and the fuel flow between the front end and the front wall. A sleeve that extends toward the front end portion of the inner cylinder through a flange having a plurality of second fuel injection holes is provided on the inner cylinder that forms the passage and the shaft that is inserted into the inner cylinder so as to move back and forth through a seal member. And a switching valve that is provided on the sleeve and that has a seal portion that protrudes outward from the inner cylinder through the fuel flow path and that faces the first fuel injection hole. 2. The fuel nozzle according to claim 1, wherein the first fuel injection hole is formed obliquely outward and the second fuel injection hole is formed in the axial direction of the shaft. 3. The fuel nozzle according to claim 1, wherein the diameter of the first fuel injection hole and the diameter of the second fuel injection hole are different.