JP2948509B2 - Burner mixer for liquid fuel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixer suitable for a liquid combustion burner for spraying and burning a liquid fuel such as petroleum.

[0002]

2. Description of the Related Art FIG. 6 shows an outline of a hot air generator for generating hot air using a liquid fuel such as petroleum. The hot air generator 1 has a combustion chamber 4 in which one surface is a panel 7 made of a heat-resistant porous metal plate and the other surface is covered with a heat insulating material 3. The liquid fuel such as kerosene sprayed from the burner nozzle 5 burns together with the combustion air supplied from the combustion fan 6. Then, the heat generated by the combustion is efficiently radiated from panel 7 to the outside as infrared rays. Liquid fuel is supplied from a fuel tank 8 to a burner nozzle 5 by a fuel pump 9. The fuel sprayed from the burner nozzle 5 is ignited by an ignition rod 10 provided near the burner nozzle 5, and combustion is started.

A mixer 20 for mixing the fuel sprayed from the burner nozzle 5 with the combustion air supplied from the combustion fan 6 is provided in front of the burner nozzle 5.

[0004] As shown in FIG.
Combustion air is supplied through a flame holding plate 13 attached to the rear end of the inner cylinder 12. The outer cylinder 11 and the inner cylinder 12 are formed by a tubular outer cylinder 11 and an inner cylinder 12.
The air for secondary combustion is supplied through the air passage 14 between the two. Further, the flame holding plate 13 is provided with a stabilizer 15 that introduces the combustion air into the inner cylinder 12 while swirling so that the liquid fuel and the combustion air are efficiently mixed and evenly burned.

[0005]

A hot air generator using a combustion device of the type which sprays and burns a liquid fuel from a burner as described above has a large combustion amount as compared with a vaporization type or a pot type. Therefore, a hot air generator having a large calorific value can be provided at low cost. On the other hand, the combustion noise is larger than that of a hot air generator of the vaporization type. In the above-described hot air generator, the combustion noise propagates directly or indirectly to the outside via a heat radiation screen or the like, so that the noise generated from the hot air generator increases. Therefore, for installation in a place requiring a relatively low noise level, such as a gymnasium or a waiting room, a hot air generator provided with a combustion device with lower noise is desirable. Then, in this invention, it aims at reducing the combustion noise in a spray-type liquid fuel combustion apparatus, and aims at providing the mixer suitable for this.

Further, it is difficult to improve the combustion efficiency of a spray type combustion apparatus as compared with a vaporization type. Therefore, an object of the present invention is to provide a mixer capable of improving the combustion efficiency in a spray type liquid fuel combustion device.

[0007]

One of the causes of the increase in combustion noise in the conventional liquid fuel combustion apparatus is that the combustion flame is swirling. In the conventional liquid fuel combustion device, as described above, the combustion flame is swirled because the combustion air is guided inside the inner cylinder in a swirled state by the stabilizer using the swirling blades. Accordingly, the air inside the mixer and the combustion chamber is easily vibrated, which causes an increase in combustion noise.

Further, since the combustion air is introduced in a swirled state, the fuel and air are mixed near the flame holding plate, and the combustion proceeds rapidly. Therefore, combustion is performed in a pressurized atmosphere having a high flow velocity immediately after being blown out from the nozzle, and this portion is a portion where the volume is rapidly expanded by the combustion and noise is generated. For this reason, combustion noise with large energy is generated, which is a factor that makes it difficult to reduce noise.

Therefore, in the present invention, there is provided a mixer installed in front of a burner nozzle for liquid fuel, in which a part of the combustion air is guided forward, and the combustion air is directed substantially in the direction of the central axis from the tip. And a substantially cylindrical frame cone that supplies a portion of the frame cone, and is arranged substantially coaxially inside the frame cone, the diameter of the front end is larger than the diameter of the rear end, and the front end is located behind the front end of the frame cone. A mixer for a liquid combustion burner, comprising: an inner cylinder; and a rectifying plate attached to a rear end of the inner cylinder and guiding a part of combustion air into the inner cylinder substantially parallel to a central axis. Is adopted.

[0010] In the mixer of the present invention, the liquid fuel sprayed from the burner nozzle moves substantially parallel by the combustion air guided from the straightening vane substantially parallel to the central axis,
It diffuses toward the front end of the inner cylinder. During this time, the liquid fuel is preheated by radiant heat or the like inside the inner cylinder and is easily vaporized. The introduced combustion air is also preheated. However, since the liquid fuel and the combustion air hardly mix inside the inner cylinder, combustion does not proceed inside the inner cylinder. On the other hand, from the front end of the inner cylinder, a part of the preheated combustion air flows through the space between the frame cone and the inner cylinder and is supplied from the front end of the frame cone substantially in the direction of the central axis. For this reason, the fuel easily vaporized by the preheating and the combustion air are rapidly mixed, and the combustion proceeds. That is, at the outlet of the mixer according to the present invention, very efficient combustion is performed by the liquid fuel which is easily vaporized and the preheated combustion air. Thus, in the mixer of the present invention, efficient combustion can be maintained without swirling the combustion flame. Further, the combustion proceeds at a low flow rate at the mixer outlet at a low flow rate in a low pressure region, so that generation of a loud energy noise can be avoided. Therefore, by using the mixer of the present invention, the combustion noise can be reduced, and the combustion efficiency can be improved.

By forming a plurality of small-diameter holes in the peripheral wall of the inner cylinder, combustion air is gradually added while passing through the inner cylinder, and the liquid fuel and the combustion air can be more efficiently mixed at the outlet of the mixer. It becomes possible.

The inner cylinder is provided with a first cylinder portion to which a current plate is attached, and a large-diameter second cylinder portion attached through a flange in front of the first cylinder portion to gradually supply liquid fuel. Environment that spreads to the public. Of course, the present invention is not limited to the two cylindrical portions, and it is also possible to use three or more cylindrical portions whose diameter gradually increases. Further, the inner cylinder may have a substantially truncated conical shape gradually expanding from the rear end to the front end. In this way, by making the rear end narrow and the front end wide, it is possible to prevent the occurrence of turbulence such as mixing of liquid fuel and combustion air inside the inner cylinder, and combustion proceeds rapidly inside the inner cylinder. Can be prevented.

Further, the flow of combustion air is changed in the direction of the central axis by extending the tip of the frame cone into a cylindrical shape having a slightly smaller diameter, and further bending the extended edge substantially at right angles toward the central axis. be able to. The diameter of the end of the frame cone may be reduced to a substantially truncated cone shape.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

[Embodiment 1] FIG. 1 shows a plan view and a cross section of a mixer according to Embodiment 1 of the present invention, and FIG. 2 shows a state where the mixer is developed into a frame cone and an inner cylinder. . FIG. 3 shows a schematic configuration of a burner using the mixer of this example.

As shown in FIGS. 1 and 2, the mixer 20 of the present embodiment includes a substantially cylindrical frame cone 21 and an inner cylinder 30 coaxially set therein. Inner cylinder 3
0 is a first cylindrical portion 31 having a small diameter located rearward, and a second cylindrical portion 32 having a larger diameter than the first cylindrical portion 31 located forward.
Which are connected by a flange 36. The first and second cylindrical portions 31 and 32 are made of stainless steel punching metal, and a plurality of small-diameter holes 35 are formed in surrounding walls 33 and 34. In addition, 3 around the first cylindrical portion 31
Metal fittings 37 for connecting to the frame cone 21 are attached at the places, and the first and second cylindrical portions 31 and 32 are connected by the connecting metal fittings 37 to the frame cone 2.
1 is coaxially fixed inside.

The frame cone 21 has a cylindrical main body 22.
The front (tip side) 23 of the second cylindrical portion 3
2 is a cylindrical portion 24 having an inner diameter slightly larger than the outer diameter. The edge 25 located at the tip of the cylindrical portion 24 is bent substantially at right angles toward the direction of the central axis. In the frame cone of this example, the inner diameter of the frame cone body 22 is larger than the inner diameter of the second cylindrical portion 32, and the inner diameter of the second cylindrical portion 32 is set to be larger than the inner diameter of the first cylindrical portion 31. . The inner diameter of the cylindrical portion 24 at the tip of the frame cone is set to be smaller than the inner diameter of the frame cone body 22 and larger than the inner diameter of the second cylindrical portion 32. And the edge 2 of the tip bent at the right angle
The inner diameter of 5 is set to be smaller than the inner diameter of the cylindrical portion 24 at the tip.

The inner cylinder 30 arranged inside the frame cone 21 is fixed so that its front end 38 is slightly behind the cylindrical portion 24 at the end of the frame cone. Therefore, the front end 38 of the inner cylinder and the cylindrical portion 2 at the tip of the frame cone
4, a narrow space 26 is secured, and combustion air is supplied to the end of the frame cone 21 through this space 26 as described later.

On the other hand, a disk-shaped current plate 40 is attached to the rear end 39 of the inner cylinder 30.

The flow regulating plate 40 is provided with a relatively large hole 41 for guiding the liquid fuel sprayed from the burner nozzle 5 to the inside of the inner cylinder 30 substantially at the center thereof. Combustion air supplied from the combustion fan at the same time as the liquid fuel is also guided from the hole 41 into the inner cylinder 30. Further, the current plate 40 of this example is provided with a plurality of small-diameter holes 42 in a row along the periphery thereof. The central hole 41 and the plurality of holes 42 formed around the hole are all provided with holes in a direction parallel to the central axis 30a of the inner cylinder, and the combustion air supplied from the combustion fan passes through the holes 41. And 42 are introduced into the inner cylinder 30 substantially in parallel with the central axis 30a.

A more detailed description will be given using the schematic configuration of a burner using the mixer of the present embodiment shown in FIG. The liquid fuel jetted forward from the burner nozzle 5 spreads substantially conically inside the inner cylinder 30 toward the front end 38 as shown by the solid line in FIG.

On the other hand, from the combustion fan 6 to the air duct 6a
The combustion air supplied to the rear side of the mixer 20 through the passage is guided to the mixer 20 as shown by a broken line in FIG.
That is, part of the combustion air is guided into the inner cylinder 30 through the central hole 41 of the current plate 40. A part of the combustion air is guided into the inner cylinder 30 through the hole 42 around the current plate 40. In addition, some of the combustion air
It is guided to the front of the frame cone 21 through a space 27 between the inner cylinder 30 and the frame cone 21. Part of the combustion air passing through the space 27 between the inner cylinder and the frame cone is also guided into the inner cylinder through a small-diameter hole 35 provided in the peripheral wall of the inner cylinder. In front of the frame cone 21, the combustion air flows along the inner surface of the cylindrical portion 24 through the space 26 between the front end 38 of the inner cylinder and the cylindrical portion 24 at the tip of the frame cone, and further, the edge of the tip Central axis 30 along 25
It changes its direction in the direction of a and flows. Due to the flow of the combustion air, mixing of the fuel and the combustion air proceeds as described later. At the same time, the flow of combustion air at the tip of the frame cone also serves to pressurize the inside of the inner cylinder.

In the mixer of this embodiment, the sprayed fuel and the combustion air flow as described above. Therefore, the fuel sprayed at a high speed from the burner nozzle 5 does not receive the swirling flow, and diffuses along the solid line in FIG. 3 while moving substantially parallel forward in the sprayed state. The combustion air supplied from the hole 42 near the circumference of the flow straightening plate and the hole 41 in the center is supplied to the central axis 3 along the directions of the holes 41 and 42.
Flows forward in parallel with 0a. Further, the combustion air guided into the inside from the holes 35 formed in the peripheral walls 33 and 34 of the inner cylinder is also swept forward by the combustion air flowing through the holes 42 near the circumference of the current plate 40. Therefore, the combustion air supplied from the hole 41 in the center of the current plate and the combustion air supplied from the hole 42 near the circumference of the current plate or the combustion air supplied from the hole 35 around the inner cylinder. Is
It flows forward inside the inner cylinder without being mixed. Since the sprayed liquid fuel is not mixed with the combustion air, the surrounding area has a low oxygen concentration. Therefore, combustion does not proceed. Further, the inner cylinder 30 of the present example is constituted by a first cylindrical portion 31 having a small diameter and a second cylindrical portion 32 having a large diameter, and the fuel spreads in a state of being inscribed therein. Therefore, turbulence does not occur along the inner surfaces of the cylindrical portions 31 and 32, and the mixing of fuel and combustion air inside the inner cylinder is prevented, so that combustion does not proceed.

Inside the inner cylinder 30, the sprayed fuel and the combustion air proceed forward without mixing.
On the other hand, the inner cylinder 3 receives radiant heat of combustion in the combustion chamber and the like.
0 and the frame cone 21 are heated. Therefore, the fuel sprayed inside the inner cylinder 30 is
Radiation heat from 0 and radiant heat from the combustion chamber are heated and easily vaporized. The combustion air is also preheated by receiving the radiant heat.

The same applies to the combustion air supplied through the space 27 between the inner cylinder 30 and the frame cone 21.

When the fuel which is easily vaporized and the preheated combustion air reach the front end 38 of the inner cylinder, the combustion is transformed into the direction of the central axis 30a through the gap 26 between the frame cone and the front end of the inner cylinder. Mixed by air. That is, near the tip of the frame cone, the fuel that is gradually diffused and preheated and the combustion air supplied to the vicinity thereof are reduced in pressure and mixed. Therefore, combustion proceeds rapidly and completely from the end of the frame cone toward the combustion chamber. Therefore,
A high combustion temperature can be obtained, and complete combustion can be obtained even if the excess air ratio is set low. It is desirable that the length of the inner cylinder 30 be set in accordance with the spray angle of the burner nozzle 5, and that the inner diameter of the edge 25 at the end of the frame cone be substantially in contact with the fuel diffused by the spray from the burner nozzle 5. desirable. If the inner cylinder 30 is too long, the front end 38
Soot is seen on the surface. Also, if the inner cylinder 30 is too short,
Combustion occurs inside the frame cone, and the effect of lowering noise is reduced.

As described above, by using the mixer of the present embodiment, highly efficient combustion can be obtained without generating a swirling flow inside the mixer. Therefore, an increase in combustion noise caused by the swirling flow can be prevented. Further, in the mixer of the present example, combustion proceeds rapidly in the decompressed region from the vicinity of the front end of the frame cone to the front. Therefore, generation of high-energy noise can be prevented, and combustion noise can be reduced. Also, since the excess air ratio can be reduced, the noise level can be reduced in this respect as well. When the noise at the heater outlet 1.5 m was measured by the experiment of the present inventors,
It has been confirmed that the use of the mixer of the present invention enables a reduction of about 5 to 8 dB as compared with the case where a mixer that causes a swirling flow is used in the related art.

Therefore, by using the mixer of the present invention, it is possible to realize a liquid fuel combustion apparatus which is suitable for a hot air generator or the like and has a large calorific value and low noise. Further, in the mixer of the present invention, the fuel and the combustion air are preheated in the frame cone, so that the combustion efficiency is improved and the burnout is improved.

Embodiment 2 FIG. 4 shows a plan view and a cross section of a mixer according to Embodiment 2 of the present invention, and FIG. 5 shows a schematic configuration of a burner using the mixer of this embodiment. is there.
As shown in FIG. 4, the mixer 20 of the present example includes a substantially cylindrical frame cone 21 and an inner cylinder 30 set coaxially inside the frame cone 21. The same reference numerals are given and the description is omitted.

The inner cylinder 50 of the present embodiment includes a rear end 52 and a front end 51
And a substantially frustoconical peripheral wall 53 that gradually widens toward. The peripheral wall 53 is made of stainless steel punched metal, and has a plurality of small-diameter holes 35 as in the first embodiment. This inner cylinder 50
At the rear end 52, a rectifying plate 40 similar to that of the first embodiment is mounted, and combustion air is introduced into the inner cylinder 50 substantially in parallel with the central axis 30a.

The distal end portion 28 of the frame cone 21 of this embodiment is substantially frustoconical with an inner diameter gradually narrowing.
Is located behind the tip portion 28. Further, a gap 26 is opened between the front end portion 28 and the front end 51, and the mixer 20 of this embodiment also has the frame cone 21.
The combustion air supplied forward through the space 27 between the inner cylinder 50 and the inner cylinder 50 is supplied from the front end portion 28 of the frame cone 21 in the direction of the central axis 30a.

As shown in FIG. 5, the mixer 2 of the present embodiment
In the burner using No. 0, the liquid fuel jetted forward from the burner nozzle 5 spreads substantially conically inside the inner cylinder 50 toward the edge of the frame cone tip as shown by the solid line. Further, the combustion air supplied from the combustion fan 6 to the rear side of the mixer 20 is supplied to the mixer 2 as indicated by a broken line.
It is led to 0. That is, a part of the combustion air passes through the central hole 41 of the current plate 40 and the peripheral hole 42,
Guided inside. A part of the combustion air is supplied to the inner cylinder 5.
In addition to being guided to the front of the frame cone 21 through the space 27 between the frame cone 21 and the inside of the inner cylinder, a part thereof is also guided to the inside of the inner cylinder through a small-diameter hole 35 provided in the peripheral wall of the inner cylinder. I will

Therefore, even inside the mixer 20 of this embodiment, the swirled fuel and combustion air are not swirled, and move substantially parallel forward. In the process, the fuel is preheated by radiant heat or the like, and the fuel is easily vaporized. Since these fuel and combustion air are abruptly mixed by the inwardly facing combustion air at the tip 28 of the flame cone, rapid and complete combustion takes place near the mixer outlet of the present example.

Therefore, by using the mixer 20 of this embodiment, highly efficient combustion can be achieved.

Further, since there is no swirling flow and combustion is performed in a portion where the flow velocity of the fuel is decreased in front of the flame cone, the combustion noise can be reduced. Therefore, by employing the mixer of the present embodiment, it is possible to realize a liquid fuel combustion apparatus having low noise and high combustion efficiency as in the first embodiment.

The above embodiments can be freely combined. For example, the inner cylinder shown in the first embodiment and the frame cone shown in the second embodiment may be combined. Further, the above embodiments are merely examples, and the present invention is not limited to the above embodiments. For example, the holes around the circumference provided on the current plate are not limited to one line and may be plural lines, and the shape is not limited to a circle but may be a square hole. Further, the inner cylinder may be configured without using punching metal. Further, the inner cylinder is not limited to the two stages in the first embodiment, but may be configured in three or more stages. In addition, the mixer of the present invention can be applied not only to the combustion device for the infrared radiation type hot air generator as described above, but also to a combustion device provided with a burner for burning liquid fuel.

[0037]

As described above, by using the mixer according to the present invention, since the combustion position is located ahead of the flame cone, the combustion and preheating of the combustion air are achieved in the flame cone, and the combustion efficiency is improved. improves. Further, the combustion air is not swirled when introduced into the mixer, and the combustion is performed in a region where the flow velocity of the fuel is low.
Therefore, combustion noise can be significantly reduced. Therefore, the mixer for a liquid fuel burner of the present invention is suitable for a combustion device used for a liquid fuel spray type hot air generator and the like, and provides a combustion device with low noise and high combustion efficiency. it can.

[Brief description of the drawings]

FIG. 1 (a) is a plan view of a mixer according to Embodiment 1 of the present invention, and FIG. 1 (b) is a side sectional view showing a part of the mixer.

FIG. 2 is an exploded perspective view showing the mixer shown in FIG. 1 in an unfolded state.

FIG. 3 is a sectional view showing an outline of a burner using the mixer shown in FIG.

FIG. 4 (a) is a plan view of a mixer according to Embodiment 2 of the present invention, and FIG. 4 (b) is a side cross-sectional view showing a part of the mixer.

FIG. 5 is a cross-sectional view schematically showing a burner using the mixer shown in FIG.

FIG. 6 is a diagram showing an example of a hot air generator.

FIG. 7 (a) is a plan view of a conventional mixer, and FIG. 1 (b) is a cross-sectional view thereof.

[Explanation of symbols]

 5 Burner nozzle 6 Combustion fan 10 Ignition rod 20 Mixer 21 Frame cone 22 Main body of frame cone 24 Cylindrical part at tip 25 Edge at tip 28 Frustoconical part of the inner cylinder 30, 50, the inner cylinder 31, the first cylindrical part 32, the second cylindrical part 35, the small-diameter holes 38, 51, provided in the peripheral wall of the cylindrical part Front end 39, 52 ... rear end of inner cylinder 40 ... current plate 41 ... center hole 42 ... hole around circumference

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-7-318010 (JP, A) JP-A 7-12706 (JP, U) JP-A 1-101023 (JP, U) JP-A 5-102 61607 (JP, U) Hikaru 1-169918 (JP, U) JP 5-51807 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F23D 11/24

Claims (6)

(57) [Claims] 1. A mixer installed in front of a burner nozzle for liquid fuel, which guides a part of the combustion air forward and supplies a part of the combustion air in a substantially central axis direction from a tip. A substantially cylindrical frame cone, and an inner cylinder which is disposed substantially coaxially inside the frame cone, the diameter of the front end is larger than the diameter of the rear end, and the front end is located behind the front end of the frame cone; A mixer for a liquid combustion burner, comprising: a rectifying plate attached to a rear end of the inner cylinder and guiding a part of combustion air into the inner cylinder substantially parallel to the central axis. 2. The mixer according to claim 1, wherein a plurality of small-diameter holes are formed in a peripheral wall of the inner cylinder. 3. The internal cylinder according to claim 1, wherein the inner cylinder has a first cylinder portion to which the rectifying plate is attached, and a large-diameter second cylinder attached to the front of the first cylinder portion via a flange. A liquid combustion burner mixer comprising: 4. The mixer according to claim 1, wherein the inner cylinder has a substantially truncated cone shape gradually expanding from the rear end to the front end. 5. The frame cone according to claim 1, wherein a tip of the frame cone extends in a cylindrical shape having a slightly smaller diameter, and an extended edge portion thereof is bent substantially at a right angle toward the central axis. Mixer of burner for liquid combustion. 6. The mixer for a burner for liquid combustion according to claim 1, wherein the end of the frame cone has a diameter reduced in a substantially truncated cone shape.