JPH0637968B2 - Burner - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial / commercial or household burner with a wide combustion heat variable range (hereinafter referred to as TDR).

Conventional technology Conventionally, a burner utilizing partial premixed combustion has been used as an industrial / commercial or household burner, and a premixed mixture of fuel and air is ignited in a flame hole to form a premixed flame. Secondary air was supplied from around the premixed flame to form a diffusion flame.

Further, a premixed counterflow burner has been proposed in which premixed flames are opposed to each other and flame holding is performed at a collision portion of the flames.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, when the burner that forms a diffusion flame around the premixed flame has a small amount of heat of combustion, or when the excess air ratio of the premixed gas approaches 1, the burner causes a rapid temperature rise. Flashback often occurs. When the excess air ratio was set to be greater than 1 or the premixed air velocity was increased, the flame became unstable, and gas was often exhausted or blown off due to incomplete combustion. Therefore, the TDR is narrow, which causes practical inconvenience.

On the other hand, in the premixed counterflow flame burner, when the combustion heat amount is increased, the speed of the premixed gas ejected from the flame hole is increased, but even in such a case, the flame has a merit that it is difficult to blow off, The flame became a turbulent flow at the collision part and the combustion noise became large, which was a problem in practical use. On the other hand, when the temperature inside the combustion chamber becomes high and the combustion heat amount is reduced to reduce the speed of the premixed gas ejected from the flame holes, flashback is likely to occur. Further, in this type of burner, when the speed of the premixed gas increases, the flame tip portions pass each other, so that the flame tip portions may not form opposed flames but may perform unstable combustion. Therefore, TDR could not be sufficiently secured.

The present invention provides a burner with a wide TDR.

Means for Solving the Problems In the first aspect of the invention, a plurality of flame holes provided in mutually facing primary combustion chamber walls forming a combustion chamber are opposed to each other and a fuel supply passage provided in an outer wall of the primary combustion chamber wall. The fuel supply passage is provided outside the combustion chamber, and the flame holes are formed into slits to form a row of flame holes in the longitudinal direction. Adjacent flame holes are separated from each other to form a combustion gas passage between them. To do. Several rows of flame holes are arranged so that the long sides of the slit flame holes face the exit of the combustion chamber. Further, each flame hole is located at the outlet of the fuel supply passage provided outside the wall of the temporary combustion chamber, and one end of the fuel supply passage communicates with the fuel branch pipe.

In the second aspect of the invention, the outer wall of the combustion chamber faces the cooling surface.

In the third aspect of the invention, the fuel supply passage is divided into small flame holes by dividing the fuel supply passage with a divider plate.

Effect According to the first aspect of the present invention, when the combustion heat amount is large, even if the flame separates from the flame hole, the flame front end approaches, so that an opposing flame is formed in the stagnation region, and stable combustion becomes possible. The premixed flame that forms in the flame hole near the exit of the combustion chamber is heated near the flame hole by the hot combustion gas generated by the premixed flame that is formed in the flame hole that is far from the exit of the combustion chamber, and the stability of the flame base Is especially good. At this time, the entire flame is not heated and the flame temperature does not rise. Furthermore, in the conventional premixed flame, it was divided into smaller flames for high-load combustion, but when the premixed air velocity is increased, it easily blows off,
TDR was small. However, in the burner of the present invention, even with a small flame, the opposing flame is stable, so that the TDR is large and high-load combustion is possible. Since the flame holes have a slit shape and the width of the flame is wide, the flame tips do not pass each other and form an opposing flame with the flame tips facing each other.

Even if the flame holes are heated, the fuel supply passage is provided outside the wall of the primary combustion chamber, so that the fuel supply passage is cooled and the premixture is not preheated.

According to the second aspect of the invention, the outer wall of the combustion chamber is the cooling surface.
The heat generated in the combustion chamber heats the wall of the combustion chamber, and the heat reaches the outer wall of the combustion chamber. At this time, if the premixed air exists on the outer wall of the combustion chamber like the conventional burner, the premixed air is preheated,
Again the heat recirculates into the combustion chamber. When the premixed air is preheated, the flame temperature becomes high, the combustion speed becomes fast, and the flashback easily occurs. In the present invention, since the combustion chamber wall is cooled,
Pre-mixture is not pre-heated and stable combustion is possible even with a small amount of combustion heat.

According to the third aspect, the flames on the divided small flame holes are combined to form a flame having a flat tip. As a result, the flat tips face each other, forming an opposing flame without passing each other. Further, if the facing portion is flat, the flame does not easily become a turbulent flow even if the premixed gas jet speed is high in the facing portion, and the laminar flow flame is maintained, and since the flame is small, there is no flashback.

Embodiment FIG. 1 is a perspective view of a partial sectional view of an embodiment of the present invention. Reference numeral 1 is a burner body, 2 is a primary combustion chamber, and 3 is a secondary fuel chamber. Reference numeral 4 is a combustion chamber composed of a primary combustion chamber 2 and a secondary combustion chamber 3. 5 is a flame hole, 6 is a burner header, 7 is a secondary air hole, 8 is a fuel supply passage, 9 is a fuel branch pipe, 10 is a header flange, 11 is a burner cover, 12 is a burner cooling passage, and 13 is secondary air. Passage, 14 bottom plate, 15 opposite flame, 16 secondary flame, 17
Is a premixed gas, 18 is secondary air, 19 is the wall of the primary combustion chamber, 20 is the wall of the secondary combustion chamber, and 21 is the outlet of the combustion chamber.

FIG. 2 is a sectional view of the embodiment of the present invention viewed from another direction. Reference numeral 22 is a slit-shaped flame hole 5, which is hereinafter referred to as a slit flame hole. Reference numeral 23 is a combustion gas passage. Reference numeral 24 is a partition plate, which divides the slit flame hole 22. 25 is a fuel header and 26 is a secondary air header. In FIG.
When the horizontal direction is the longitudinal direction of the burner, the slit flame holes 22 are arranged in the longitudinal direction of the burners, and the slit plate 14 is also in the longitudinal direction.

3 (a) and 3 (b) are characteristic flame shape diagrams of the first invention. 27 is combustion gas.

The burner header 6 includes a fuel branch pipe 9, a large number of fuel supply passages 8 communicating with the fuel branch pipe 9, and a header flange 10. The outlet of the fuel supply passage 8 serves as a flame hole 5. Primary combustion chamber 2 and secondary combustion chamber 3
The combustion chamber 4 is composed of a plurality of header flanges 10 arranged side by side to form a primary combustion chamber wall 19, which are opposed to each other to form the primary combustion chamber 2, and a rectangular bottom plate 14 is provided on the bottom thereof. . A large number of slit flame holes 22 are provided in the primary combustion chamber wall 19, and the slit flame holes 22 of the facing primary combustion chamber wall 19 are coaxially arranged so as to face each other. The secondary combustion chamber 3 comprises secondary combustion chamber walls 18 facing each other. A large number of secondary air holes 7 are provided in the secondary combustion chamber wall 18.

In the above embodiment, the fuel and the primary air are mixed to form the premixed gas 17, which is supplied to the fuel branch pipe 9 which communicates with the fuel header 25 through the fuel header 25 and the slit flame hole 22. Is ejected into the primary combustion chamber 2. Meanwhile, the secondary air
18 passes through the secondary air header 26 and is supplied to the burner cooling passage 12 that communicates therewith, and the primary combustion chamber wall 19 and the fuel supply passage 8
And is supplied to the secondary combustion chamber 3 through the secondary air holes 7 while increasing the temperature. The burner cooling passage 12 forms a part of the secondary air passage 13. The secondary air passage 13 includes a burner header 6 and a burner cover 11.

Premixture 17 ejected from the slit flame hole 22 into the primary combustion chamber 2
When the injection speed of the premixed gas 17 is high, the flame separates from the slit flame hole 22 and the opposing flames form the opposing flame 15 close to each other. Oncoming flame 15
Often burn away from the slit flame holes 22,
A part of the premixed gas is discharged from the vicinity of the slit flame holes 22 without being burnt, but since a plurality of rows of the slit flame holes 22 are separated and arranged toward the combustion chamber outlet 21, the unburned gas mixture is not burned. The air-fuel mixture is completely burned by the flame near the combustion chamber outlet 19. In addition,
If the excess air ratio of the premixed gas is 1 or less, the secondary air hole 7
A secondary flame is formed by the secondary air 18 supplied from the secondary air 18, and complete combustion occurs.

The feature of this embodiment is that the opposing flame is stably formed. For that reason, the slit flame holes 22 are adopted and the arrangement thereof is devised. 1 and 3 show detailed views of the opposing flame 15 near the outlet of the combustion chamber. The premixed gas 17 ejected from the slit flame hole 22 forms the opposing flame 15. When the jet speed of the premixed gas 17 is high, the flame tips collide. Combustion gas 27 is a combustion gas passage 23 provided between adjacent slit flame holes 22.
Through to the combustion chamber outlet 21. At this time, a slight change in the combustion gas flowing through the combustion gas passage 23 toward the combustion chamber outlet 21 causes the flame tip to move toward or away from the adjacent flame. If the shape of the flame hole is circular, the flame becomes a cone and the flame tip portions often pass each other. However, when the slit flame holes 22 are formed as in the embodiment, the flame tip portions can face each other.

Also, the opposing flame 15 is bent 15a toward the combustion chamber outlet 21. In particular, the flame after the collision faces the combustion chamber outlet 21. The combustion gas passage 23 reduces this bending. In the absence of the combustion gas passage 23, the combustion gas 27 flows between the opposing flame tips, so that the flame tips do not collide but face the exit of the combustion chamber, and the stability of the flame deteriorates.

Further, in this embodiment, the slit flame hole 22 is formed by the primary combustion chamber wall 19
Is located at the outlet of the fuel supply passage 8 provided on the outside. Even if the periphery of the slit flame hole 22 is heated, the fuel supply passage 8
The cooling does not raise the temperature and the premixed gas is not preheated. Therefore, there is no flashback due to preheating of the premixed gas.

The second invention of the present invention is characterized by cooling the outside of the primary combustion chamber wall 19. The high temperature combustion gas and flame generated in the primary combustion chamber 2 heat the primary combustion chamber wall 19, but the primary combustion chamber wall 19 is cooled, so that the temperature rise is prevented. If the outside of the primary combustion chamber wall 19 is not cooled,
As the temperature inside the combustion chamber rises, the temperature inside the combustion chamber wall rises, causing thermal deformation and thermal deterioration of the primary combustion chamber wall 19, or preheating the premixed gas to cause flashback. In particular, when the temperature in the combustion chamber rises, the combustion reaction of the flame becomes intense, the fires facing each other collide violently, and the combustion noise becomes loud. When the primary combustion chamber wall 19 is cooled, the flame base part floats up even when the premixed gas jet speed is small, but an opposing flame is formed at the flame tip part, and the flame is quietly and stably combusted in a laminar flow.

FIG. 4 is a characteristic flame form diagram of the embodiment in the third invention of the present invention. 28 is a small flame hole, 29 is a fuel supply path, 30 is a small flame hole flame, 31 is a combined flame, 32 is a twin flame, and 33 is a stagnation part. FIG. 4 (a), FIG. 4 (b), and FIG. 4 (c) show the case where the injection speed of the premixed gas 17 is low, the case where it is intermediate, and the case where it is high.

In FIG. 4 (a), the flame base is formed by adhering to the small flame holes 28. Each of the small flame holes 28 has a fuel supply passage 29, and has a Poiseuille flow. When the length of the fuel supply passage 29 is L and the hydrodynamic diameter of the slit is D, the flow velocity distribution of the premixed gas in the fuel supply passage 29 becomes Poiseuille flow when L / D is large.
When L / D ≧ 5, almost Poiseuille flow is obtained. When L / D is large, the base portion of the opposing flame 15 adheres to the flame hole even if the premixed gas ejection speed is high. A plate between the small flame holes 28 and the small flame holes 28
Although it is divided by 24, this structure has a simple structure and is easy to process. The heat from the flame is transferred to the divider plate 24 to prevent flashback.

Fig. 4 (b) shows a combined flame 3 in which two small flame holes are combined.
1 is shown. The flame tip of the premixed gas ejected from each small flame hole remains.

In FIG. 4 (c), the tip of the flame is flat with the tip of the flame approaching at the stagnation portion 33. This state is generally called twin flame 32 among the opposing flames. Since the flow velocity becomes zero in the stagnation part 33, this flame is stable even if the premixed air velocity is high. At this time, due to the two small flame holes,
The tip of the flame becomes flat, and the twin flame 32 can be easily formed.

EFFECTS OF THE INVENTION The present invention provides a burner that burns stably even when the heat of combustion is large and that produces quiet combustion noise. Slit flame hole
Twenty-two rows are arranged toward the exit of the combustion chamber, and the adjacent flame holes are used as combustion gas passages 23. Furthermore, by making each flame hole an outlet between the fuel supplies installed outside the combustion chamber wall, there is no rise in flame temperature, and even if the combustion heat amount is large, an opposing flame is formed in the stagnation region, and therefore stable. Moreover, combustion with low combustion noise can be performed, and TDR is large.

Further, the outer wall of the combustion chamber wall is cooled to prevent the temperature of the combustion chamber wall from rising, but the flame stability is ensured by the opposing flame. Also, the flame quietly and stably burns in the stagnation area.

By dividing the slit flame hole, the flame tip is flattened, the flame tips are easily opposed to each other, and flame stability is further enhanced.

[Brief description of drawings]

FIG. 1 is a perspective view of a partial cross section of a burner according to an embodiment of the present invention, FIG. 2 is a sectional view of the same embodiment, FIG. 3 is a flame form diagram of the same embodiment, and FIG. It is a flame form figure of a different Example. 1 ... Burner body, 2 ... Primary combustion chamber, 22 ... Slit flame hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Okamoto ▲ Ken ▼ ya 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kenkichi Hashido, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Stock In-house (56) References JP-A-52-23736 (JP, A) Actual development-Sho 54-71236 (JP, U) JP-B 59-7884 (JP, B2)

Claims (3)

[Claims] 1. A large number of slit-shaped flame holes provided on the walls of primary combustion chambers which face each other and constitute a combustion chamber are opposed to each other, and the slit-shaped flame holes are arranged in the longitudinal direction, and adjacent short sides are arranged. Combustion gas passages are formed by separating, the long sides of the slit-shaped flame holes are separated and arranged in several rows in the direction of the exit of the combustion chamber, and a large number of fuels are communicated from the outside of the primary combustion chamber wall. A burner in which the outlet of the supply passage is the slit-shaped flame hole. 2. The burner according to claim 1, wherein the outer wall of the combustion chamber serves as a cooling surface. 3. The burner according to claim 1, wherein a slit-shaped flame hole is divided by disposing a slit plate in the longitudinal direction of the flame hole.