JPH0211807B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gun-type liquid fuel vaporizing burner used in domestic water heater boilers and the like.

(Prior Art) Various structures are conventionally known as this liquid fuel vaporization burner, and as an example, the applicant of the present application has filed a burner shown in FIG. 5 as Utility Model Application No. 12466/1983.

To explain the burner shown in Fig. 5 above, a straight cylindrical air outlet 2 is provided coaxially with the nozzle surrounding a fuel spray nozzle 1 facing into the combustion chamber, and a straight cylindrical air outlet 2 is provided in front of the air outlet 2. A burner cone 4 made of porous ceramic and formed into a cylindrical shape comprising a cylindrical part with a combustion gas suction port 3 provided between the opening and the expanding part that continuously expands forward at the front end of the cylindrical part. is provided coaxially with the nozzle 1 surrounding the fuel spray area of the nozzle 1, and is formed at the outlet of the burner cone 4 in the shape of a hollow cone or hemisphere with an open bottom and made of porous semiconductor similar to the burner cone 4. A burner cup 6 with a small hole 5 bored in its circumferential surface is arranged coaxially with the burner cone 4 with its convex surface facing inside the burner cone 4, and the front of the burner cup 6 has a substantially U-shaped or nine-shaped cross section. By providing an annular flame stabilizing ring 7 coaxially with the burner cup 6, unburned oil droplets that are ejected from the fuel spray nozzle and collide with the burner cone and burner cup are temporarily kept inside the burner cone and burner cup. This is evaporated using the heat of the cone heated by the combustion heat and released as steam, and the suction force generated by blowing air from the air outlet causes high-temperature combustion from the combustion gas intake port. Gas is sucked into the burner cone to promote gasification of the fuel, and this gasified fuel is mixed with air blown out from the air outlet and flowing through the center of the burner at the burner cone outlet, and the gas is mixed with the air that flows behind the burner cup and flame holding. A stable blue flame is formed around the small holes of the burner cup and the flame-holding ring using the high-temperature combustion gas that stays behind the ring as the ignition source.

That is, as shown in Figure 5, this burner has a nozzle area (a), a combustion air area (b), a fuel vaporization area (c), and a mixing area.
By completely separating (d), combustion zone (e), and high-temperature combustion gas circulation zone (f), the oil droplets sprayed from the nozzle in the nozzle zone are first ignited in the form of oil droplets in the fuel vaporization zone. The gaseous fuel is thermally vaporized by high-temperature combustion gas sucked through the circulation zone without heating, and then the gaseous fuel is mixed with air in the mixing zone, and then stabilized in the combustion zone. It is designed to ignite.

However, according to subsequent research by the applicant, the air outlet of the burner described above is formed in a straight cylindrical shape, and the blown air flows linearly in the direction of the outlet. The fuel gas, which is gasified by the drawn-in high-temperature combustion gas and the heat of the cone and flows near the inner wall of the cone and does not reach the flammable limit due to lack of oxygen, and the air flowing through the center of the cone are separated and released from the cone outlet. It was found that the gasified fuel and air were not completely mixed at the cone outlet.

Therefore, a plurality of air outlets 2 are arranged at equal intervals in the circumferential direction around the fuel spray nozzle 1, as shown in JP-A-59-145442 shown in FIG. It is also possible to mix fuel and air by creating a swirling flow in the blown air by tilting each at a predetermined angle in the circumferential direction, but since the swirling flow has the property of spreading outward, it is difficult to There is a possibility that suction of combustion gas may be obstructed.

Further, if the gasified fuel and air are mixed inside the burner cone, a flame will be generated inside the burner cone, preventing complete blue flame combustion and causing a problem of loud combustion noise.

(Problems to be Solved by the Invention) The problems to be solved by the present invention are to create a flow in which the blown air is swirled but not spread outward, and the gasified fuel and air are mixed inside the burner cone. However, the goal is to ensure that it does not burn inside the cone.

(Means for Solving the Problems) The technical means taken by the present invention to solve the above problems include a fuel spray nozzle, an air outlet provided around the fuel spray nozzle, surrounding the nozzle, and coaxially with the fuel spray nozzle. The rear part is formed into a generally cylindrical shape, and a conical widening part is formed at the front end of the cylindrical part and continuously widens forward at an angle slightly narrower than the spray angle of the fuel spray nozzle. a burner cone that surrounds the spray area and is provided coaxially with the nozzle and air outlet, and forms a combustion gas suction port between the rear end opening and the air outlet; and a burner cone that is formed in a hollow conical shape with an open bottom. A suitable number of small holes are bored at suitable positions other than the pointed head, and a convex surface is provided inside the burner cone at the outlet opening at the front end of the burner cone, and the outlet part of the burner cone is arranged coaxially with the burner cone. A burner cup having an appropriate gap between the burner cone and the burner cup, and a flame stabilizing ring coaxially provided in front of the burner cup with an appropriate interval therebetween, are provided to make the burner cone and burner cup water absorbent. In a liquid fuel vaporizing burner made of porous ceramic, the air outlet has blades arranged at equal intervals in the circumferential direction at the front end of the air outlet and inclined at a predetermined angle in the circumferential direction, and a contractile flow inclined forward and diagonally inward. The burner cup is provided with a swirler having a forming part, the apex angle of the burner cup is made slightly larger than the spread angle of the burner cone, and the burner cup is located in front of the swirler within the burner cone.

(Function) According to the present invention, the air blown out from the air outlet is blown out as a spiral flow by the blades of the swirler blades, and is converged inward by the contracting flow forming part. guided and prevented from spreading outward.

On the other hand, fuel is sprayed from the fuel spray nozzle, hits the burner cone and baffle plate, and is gasified by its heat and by the high-temperature combustion gas sucked into the cone from the combustion gas suction port, and is agitated by the swirling air flow. The gas is thoroughly mixed with air and discharged from the burner cone outlet.

The gasified fuel and air are mixed inside the burner cone, but the shape and position of the burner cup prevent the air-fuel mixture from stagnation inside the burner cone. Since the flow velocity of the air-fuel mixture is faster than the propagation velocity of the flame, flashback does not occur and no flames form inside the burner cone.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

The burner indicated by the symbol A in the drawing has a fuel spray nozzle 1, an air outlet 2 provided around the fuel spray nozzle 1 surrounding the nozzle 1, a swirler 10 provided in front of the air outlet 2, and a fuel sprayer. It includes a burner cone 4 provided surrounding the fuel spray area of the nozzle 1, a burner cup 6 inserted into the outlet of the burner cone 4, and a flame-holding ring 7 provided in front of the burner cup 6.

The air outlet 2 is formed by a straight cylinder 12 provided through the center of a mounting flange 11 attached to a flange pipe (not shown) of the combustion chamber, and the rear part is connected to the air passage 14 of the blower 13. At the same time, a swirling wing 10 is provided at the front end.

Further, a nozzle holder 13 is provided coaxially within the air outlet 2, and the tip of the fuel spray nozzle 1 held by the nozzle holder 13 faces the center of the burner cone 4 from the front end opening of the air outlet 2. There is.

The fuel spray nozzle 1 is a nozzle with a spray angle of 60° and has a conventionally well-known structural form, and has a rear end formed by penetrating the nozzle holder 13 in the axial direction and an oil supply hole 14 and a feed line connected to the oil supply hole 14. Oil pipe 15
Contact the refueling source via.

The oil pipe 15 is equipped with an electromagnetic pump 16 and a strainer 17 in the middle.

The electromagnetic pump 16 and the strainer 17 are attached to a backing plate 18 attached to the back surface of the mounting flange 11, and are integrally installed in the burner A.

The backing plate 18 attaches the air passage component 19 to the flange 1.
1 to form an air passage 14 that connects the blower 13 and the air outlet 2, and is integrally provided with an air passage forming member 19 on the back side.

Furthermore, recesses 20 and 21 for inserting the oil pipe and the igniter are formed on the side of the contact plate 18 that contacts the mounting flange 11 so as to have a gap between the oil pipe 15 and the igniter. Igniters 22 are provided through the recesses 20 and 21, respectively.

A pair of igniters 22 are provided between the fuel spray nozzle 1 and the swirler 10 at positions approximately 120 degrees from above with respect to a perpendicular line passing through the center of the fuel spray nozzle 1, and extend from below to above, with their tips close to the nozzle 1. Compatible.

In addition, in FIG. 3, reference numeral 23 indicates a butterfly bolt for fixing the contact plate 18 to the mounting flange 11.

The swirling blade 10 includes a tapered tube-shaped contracted flow forming part 9 whose diameter gradually decreases toward the front, and a plurality of contracted flow forming parts 9 formed by cutting and raising the contracted flow forming part 9 at equal intervals in the circumferential direction, each inclined at a predetermined angle in the circumferential direction. In the illustrated example, a straight cylindrical part 24 extends from the rear end of the contraction forming part 9, and a flange 25 is provided at the rear end of the cylindrical part 24, and the cylindrical part 24 is connected to the air outlet 2. It is provided so as to cover the air outlet 2 by fitting into the front end of the cylinder 12 and screwing the flange 25 to the mounting flange 11.

Further, in the swirling blade 10, a part of the blade 8 and the contracted flow forming part 9 are cut out and a fire transfer plate 27 is provided in the part 26, which is located in the vicinity of a position of 120 degrees with respect to a perpendicular line passing through the center. That is, the fire transfer plate 27 is provided at the back of the igniter 22.

The fire transfer plate 27 is provided along the outside of the swirler blade 10, and its front half is inclined inward and diagonally forward like the contracted flow forming part 9 of the swirler blade 10, and extends beyond the tip of the blade piece 8. The front end is formed wide and has an inclined angle so as to block the flow of air blown out from the air outlet 2 and a part of the oil mist sprayed from the fuel spray nozzle 1, and to cause the air-fuel mixture to stagnate behind it. It is loosely formed. That is, this fire transfer plate 27 forms a retention point for the air-fuel mixture behind it, thereby improving ignition performance and ensuring ignition.

The burner cone 4 has the shape shown in the figure, that is, a straight or slightly tapered cylindrical portion 4a is formed at the rear, and a tapered tubular shape that extends continuously from the front end of the cylindrical portion 4a and expands forward. 4b is formed, and the mounting flange 11
The fuel spray nozzle 1 is held in front of the swirler 10 by a suitable holding member 28 screwed and fixed to the
The nozzle 1 is provided coaxially with the nozzle 1, surrounding the fuel spray area.

A gap 3 is provided between the opening at the rear end of the burner cone 4 and the air outlet 2, and the gap 3 is
It constitutes a suction port 3 that sucks high-temperature combustion gas within the combustion chamber into the burner cone 4 by utilizing the negative pressure generated around it due to high-speed air blowing from the air blowout port 2 .

The burner cup 6 is formed into a roughly conical shape with an open bottom, and a large number of small holes 5 are formed on the circumferential wall thereof, with the center of the pointed head shaped like a circle and the middle part of the axial direction shaped like a ring. Open in parallel.

Then, the burner cup 6 has its convex surface facing the burner cone 4 side, and most of it is attached to the burner cone 4 side.
It is provided coaxially with the burner cone 4 in a state inserted therein, and an annular gap 29 is formed between its outer periphery and the inner periphery of the burner cone 4.

When the burner cup 6 is inserted into the burner cone 4, the change in cross-sectional area between the burner cup 6 and the burner cone 4 is small, making it difficult for the mixture of air and gasified fuel to stagnate in the burner cone 4. Moreover, the cross-sectional area of the annular gap 29 is formed to be narrow enough to make the flow velocity of the air-fuel mixture faster than the propagation velocity of the flame.

That is, the burner cup 6 has a pointed angle slightly larger than the spread angle of the burner cone 4, and the pointed end penetrates deeper into the burner cone 4 compared to the conventional one shown in FIG.
It is formed in such a length that it can be brought close to the nozzle 1.

In addition, from the viewpoint of eliminating stagnation of the air-fuel mixture in the burner cone 4 and preventing backfire, it is desirable that the tip of the burner cup 6 be as close to the nozzle 1 as possible; however, if it is too close to the nozzle 1, the atomization may occur. Since most of the fuel hits the burner cup 6, it becomes liquid and drips, reducing the vaporization efficiency.
The cusp angle and length must be determined by taking into account the balance between the above two aspects.

The burner cone 4 and burner cup 6 mentioned above are made of ceramic made of 42% silicon, 18% silicon nitride, and 40% clay, and are formed to have a porosity of 50 to 20%.

Further, the burner cone 4 and the burner cup 6 are connected and fixed by a plurality of bolts and nuts 30 and 34 while maintaining the distance between them.

The bolt 30 has a threaded portion 30a formed only in a portion extending over an appropriate length at the tip end of the shaft.
The shaft portion 30b other than 0a is formed into a round bar with a diameter of 3 mm or less and a smooth surface. The threaded portion 30a is formed to have a slightly larger diameter than other portions.

The bolt 30 is inserted from the outside of the burner cone 4 through the cone retaining sleeve 33 through the bolt insertion holes 31 and 32 formed in the protection tube 38 and the burner cone 4, and the threaded portion 30a is inserted into the mounting hole formed in the burner cup 6. 39, and a nut 34 is screwed into the threaded portion 30a from inside the burner cup 6.

The cone retaining sleeve 33 and the nut 34 have flanges 33a and 34a, respectively.
The burner cone 4 and burner cup 6 are held between them by 34a.

A bolt insertion hole 32 of the burner cone 4;
The burner cup 6 has three mounting holes 39 provided at equal intervals in the circumferential direction.

Therefore, burner cone 4 and burner cup 6
means bolts 30 at three equally spaced locations in the circumferential direction,
They are connected and fixed by a nut 34, and held coaxially with a circumferential gap 29 maintained between them by mutual tension between the bolts 30.

In addition, the bolt insertion hole 31 of the protection tube 38 has a diameter comparable to that of the collar 33a of the cone stopper sleeve 33,
Inside is a ring-shaped heat-expandable ceramic 4.
0 is fitted.

Therefore, the heat-expandable ceramic 40 is heated by the burner A and expands in the thickness direction, thereby firmly fixing the bolt 30 and nut 34 without rattling.

On the other hand, the heat-expandable ceramic 40 has its outer circumferential surface covered by the protective tube 38, its inner circumferential surface and upper surface covered by the cone stopper sleeve 33, and its lower surface covered by the burner cone 4, so that only a few exposed parts are covered. , will not weather or wear out due to contact with combustion gas, etc.

By having the bolt/nuts 30 and 34 in this structure, it is possible to prevent the air-fuel mixture from stagnation behind the bolt 30 and to prevent a flame from starting inside the burner cone 4.

The flame-holding ring 7 is welded and fixed to a column 35 extending from the mounting flange 11, and is provided coaxially with the column in front of the burner cup 6.

The flame stabilizing ring 7 includes an annular side wall portion 7a and a rear eave portion 7 extending diagonally forward inward from the rear end of the side wall portion 7a.
b, and a front eave part 7c which is longer than the rear eave part 7b and extends diagonally inward and forward from the middle of the side wall part 7a at a gentler angle than the rear eave part 7b. A small hole 36 is bored and an uneven notch 37 is formed along the inner peripheral edge.

In addition, 38 in the figure is a protective cylinder made of ceramic fiber fitted to the outer periphery of the burner cone 4, and this protective cylinder 38 is inserted in order to allow the bolt 30 to pass through.
The hole 39 is made slightly larger, and a heat-expanded ceramic ring 40 is inserted between the inner periphery of the hole 39 and the bolt 30 to prevent the bolt 30 from rattling.

Further, in the figure, 41 is a red flame detection rod, and 42 is a flame rod.

Therefore, in such burner A, the blower 13
When the electromagnetic pump 16 is operated and the igniter 22 is ignited, the spark from the igniter 22 ignites the air-fuel mixture remaining behind the spark transfer plate 27 provided in front of the igniter 22.

Subsequently, the flame behind the fire transfer plate 27 is swept downward by the vortex of air, and ignites the oil droplets that are not completely vaporized in the early stages of combustion and flows down along the inner surface of the burner cone 4 from below. The flame spreads upward along the flow and forms a yellow flame inside the burner cone 4.

Therefore, the falling oil droplets are reliably burned, and problems such as dripping of the oil droplets do not occur.

On the other hand, the air blown out from the air outlet 2 is given a swirl by the blades 8 of the swirler blades 10, but at the same time, it is prevented from expanding outward by the action of the contraction flow forming part 9 and converges inward. Since the flow is condensed, it produces a suction effect and draws in high-temperature combustion gas.

As a result, a circulating flow is generated from the outlet of the burner cone 4 to the inside of the cone 4 through the gap between the inlet of the burner cone 4 and the air outlet 2, that is, the combustion gas suction port 3.

After ignition, hot combustion gas is sucked into the burner cone 4 by the above-mentioned circulation action, and the atomized fuel is instantaneously vaporized by the heat. The vaporized fuel is cone 4
Forms an oxygen-deficient layer along the inner surface with the circulating gas.

In addition, oil droplets that are sprayed from the spray nozzle 1 and not vaporized by the suctioned combustion gas collide with the inner circumferential surface of the burner cone 4, especially the inner circumferential surface of the expanded portion.
Since the cone 4 is made of water-absorbing porous ceramic, it is once sucked into and held within the ceramic. Since the cone 4 is heated to a high temperature due to convective heat transfer by the high-temperature combustion gas, the inhaled fuel quickly evaporates and vaporizes.

That is, a vaporized region (c) is formed on the inner surface of the cone 4.

Combustion air flows inside the vaporization zone (c), and since this air is a swirling flow, the fuel gasified in the vaporization zone (c) flows inside the vaporization zone (c). The mixture is sufficiently mixed with the mixture, and is discharged from the cone 4 outlet as an air-fuel mixture.

That is, a mixing zone (d) is formed adjacent to the inside of the vaporization zone (c). Note that, as described above, since the air is in a swirling flow, the flow is uniform at the outlet of the burner cone 4.

On the other hand, the yellow flame inside the burner cone 4 moves to the downstream part of the burner cup 6 at the same time as the combustion gas is sucked in, where the mixture ignites and becomes a blue flame.

The recess behind the burner cup 6 serves as a retention point for the airflow, and the high-temperature combustion gas is retained in this area.
It serves as an ignition source for the fuel gas released from the cone 4 outlet. Therefore, a blue flame will come out from the small hole 36 made in the burner cup 6.

In addition, the burner cup 6 is made of porous ceramic that has the same water absorbing properties as the burner cone 4 as in the above embodiment, so that in addition to rectifying the airflow and ignition source, the burner cup 6 also serves as a fuel vaporizer like the burner cone 4. Although it is possible to perform the function as a surface, it is also optional to construct it with a metal plate having a large number of small holes.

Further, the unburned gas that is not ignited at the end of the burner cup 6 flows along the inner and outer peripheral surfaces of the flame-holding ring 7 and is ignited in the recessed portion behind the flame-holding ring 7.

Similar to the recess behind the burner cup 6, the recess behind the flame-holding ring 7 serves as a retention point for airflow, and high-temperature combustion gas remains in this area, which becomes a source of ignition for unburned gas that is not ignited in the burner cup 6. becomes.
Therefore, a stable blue flame will stand at the end of the flame-holding ring 7 and the small holes 36.

That is, a combustion zone (e) is formed in the flame stabilizing ring 7 portion.

Since the present invention has the above configuration, it has the following advantages.

(1) Since a swirling blade is provided at the front end of the air outlet, the swirling blade includes blades that are arranged at equal intervals in the circumferential direction and are inclined at a predetermined angle in the circumferential direction, and a contracted flow forming part that is inclined forward and diagonally inward. The air blown out from the air outlet swirls in a vortex shape, promoting mixing with the vaporized gasified fuel. In addition, the air is guided diagonally inward by the contracted flow forming part, so it does not spread outward despite being in a vortex state, and the suction of combustion gas from the combustion gas suction port is prevented. Does not interfere.

(2) The point angle of the burner cup was made slightly larger than the spread angle of the burner cone, and the position of the burner cup within the burner cone was placed in front of the swirler, so the cross-sectional area between the burner cup and the burner cone changed. is small, so that the mixture does not stagnate inside the burner cone, and the cross-sectional area is narrow enough to make the flow rate of the mixture faster than the flame propagation speed, so that the gasified fuel and air are separated inside the burner cone. Even though the mixture is mixed, there is no flame inside the burner cone.

(3) Due to (1) and (2) above, the nozzle region, combustion air region, fuel vaporization region, mixing region, combustion region, and high temperature combustion gas circulation region are more completely separated, and combustion efficiency is improved.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view of a liquid fuel vaporizing burner showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line - - of Fig. 1, and Fig. 3 is a rear view partially cut away. Shown cut away. Figure 4 is a perspective view of the swirler;
FIG. 6 is a sectional view showing an example of a conventional liquid fuel vaporization burner. 1...Fuel spray nozzle, 2...Air outlet, 3
... Combustion gas suction port, 4 ... Burner cone, 5
... Small hole, 6 ... Burner cup, 7 ... Flame holding ring, 8 ... Wing piece, 9 ... Contraction forming part, 10 ...
swirl wing.

Claims (1)

[Claims] 1. A fuel spray nozzle, an air outlet provided around the fuel spray nozzle surrounding the nozzle and coaxial with the nozzle, and a rear portion formed into a generally cylindrical shape, continuous with the front end of the cylindrical portion and extending forward of the nozzle. A tapered tubular widening part is formed that widens at an angle slightly narrower than the spray angle, and is provided coaxially with the nozzle and the air outlet, surrounding the fuel spray area of the fuel spray nozzle, and connecting the rear end opening and the air outlet. The burner cone forms a combustion gas suction port between the burner cone and the outlet, and the burner cone is formed into a hollow cone shape with an open bottom and an appropriate number of small holes are drilled at appropriate positions other than the pointed end. A burner cup is provided with a convex surface inside the burner cone and arranged coaxially with the burner cone, and has an appropriate gap between it and the rim of the burner cone outlet. In a liquid fuel vaporizing burner, the burner cone is made of water-absorbing porous ceramic, and the burner cone is made of water-absorbing porous ceramic. A swirling blade is provided, which includes a blade piece that is tilted at a predetermined angle in the circumferential direction, and a contracted flow forming portion that is tilted forward and diagonally inward. A liquid fuel vaporizing burner characterized in that the cup is located in front of the swirling blade in the burner cone.