JPS5833444B2 - combustion device - Google Patents

Description

Detailed Description of the Invention The present invention mixes air with atomized particles supplied to a combustion chamber from an atomization nozzle such as an atomization nozzle that atomizes fuel using ultrasonic vibrations or a pressure-type atomization nozzle. Regarding the combustion equipment that performs combustion, in detail, it is related to the mixing mechanism of atomized particles and air, which aims to completely mix the particles scattered at low speed with the combustion air, and prevents pulsating combustion flames and flying flames. To provide a combustion device that produces stable combustion with no combustion noise and low combustion noise.

The technology of atomizing liquid using the energy of ultrasonic vibrations is well known, and most of them involve applying vibrations to an excitation surface with a certain area that is excited by ultrasonic waves in a very high frequency range.
The liquid to be atomized is supplied, the surface tension of the liquid forms a very thin liquid film, and the liquid film develops into very thin atomized particles under the influence of vibration.

However, when fuel is atomized using ultrasonic vibration, the kinetic energy of the particles themselves is extremely small, and the atomized particles scatter forward from the vibrating surface, making it extremely difficult to achieve with conventional pressure-type atomizing burners. Unlike particles sprayed from a small-diameter nozzle hole, which have a fixed spray pattern, the particles do not exhibit a fixed spray pattern at all.

Moreover, since the atomized particles settle immediately from the excitation surface, the area near the excitation surface becomes a fuel-rich region, and when the area leaves the vicinity of the excitation surface, the fuel becomes an extremely lean region.

For this reason, it is difficult to achieve uniform permeability of combustion air into the particle group, resulting in unstable ignition mixing region and uneven mixing within the entire particle group, resulting in poor ignition characteristics and flame formation. The combustion noise was increased due to pulsation and flying sparks, which led to incomplete combustion.

Furthermore, even with conventional pressure-type atomizing nozzles, which have a much larger initial ejection velocity than ultrasonic atomization and exhibit a constant atomization pattern, the velocity is too high and there is a problem with the air. As a means of ensuring the degree of mixing, it was necessary to extremely agitate the combustion air, which resulted in high combustion noise.

The present invention solves the above problems regardless of the properties of atomized particles obtained by various atomization methods, and provides a highly reliable combustion device.

Embodiments of the present invention will be described below with reference to the drawings.

A cylindrical bottom plate 3 has a refractory material 1 disposed at the inner bottom and a drain pipe 2 penetrating through the refractory material 1 at the center of the bottom. At the top of the cylindrical bottom plate 3, air holes 4 are arranged radially on the peripheral wall and adjacent to the air holes 4. A rotating cylinder 6 having a rotating blade 5 formed by cutting and raising the rotating cylinder 6 is provided.

Furthermore, an intermediate ring 7 having a diameter larger than the diameter of the rotating tube 6 is provided on the rotating tube 6 via a partition plate 8, and the uppermost portion of the intermediate ring 7 has a diameter equal to the diameter of the rotating tube 6. Alternatively, a cylindrical combustion tube 9 narrowed to a small diameter is provided.

The above-mentioned members are attached to a burner pace 11 with a cylindrical burner casing 10.

On the other hand, the ultrasonic atomizer 12 is provided at the intermediate ring 7, and the small diameter end 12a side, that is, the nozzle side penetrates the cylindrical burner casing 10 and the intermediate ring 7, and the atomizing surface 13 thereof are arranged so as to face the inner wall surface of the intermediate ring 7.

Reference numeral 14 denotes a fuel supply pipe, which is connected to a fuel supply passage 14a passing through the central axis of the atomizer 12.

15 is a blower tube, as shown in Fig. 2, the burner casing 1
The opening is provided so as to face in the tangential direction inside the casing 10 with respect to the casing 10.

Note that 16 is a flame stabilizing plate installed on the upstream side of the swirling flow of combustion air with respect to the atomization surface 13 facing the inner surface of the intermediate ring 7.

Reference numeral 17 denotes a communication hole bored near the periphery of the atomization surface 13 of the intermediate ring 7.

In the above configuration, the operation will be explained next.

A fuel supply device (not shown) is activated to supply fuel to the atomization surface 13 via the fuel supply pipe 14 and the fuel supply path 14a.

The fuel forms a thin liquid film on the atomization surface 13;
Since the is vibrating ultrasonically, the liquid film becomes fine atomized particles and scatters forward under the influence of the vibration.

On the other hand, combustion air is sucked in from the outside by a blower (not shown) and guided into the burner casing 10 through a blower tube 15 .

Thereafter, it passes through the air port 4 of the rotating cylinder 6 and is rotated by the rotating blade 5.

Accordingly, the atomized particles mix with the swirling air and are ignited by an ignition means (not shown) to form a combustion flame.

The features of the above configuration are as follows.

(1) When a forced swirling flow is formed along the inner circumferential wall surface of the swirling tube 6, particles with extremely low particle speeds, such as the ultrasonic atomizer 12, can completely rotate the particle group depending on the swirling flow. do.

Therefore, by the time the atomized particles reach the upper part of the combustion tube 9, the atomized particles are uniformly mixed into the air due to the swirling action.

In other words, since particles have a long residence time in the air until they are combusted, they are completely mixed and can achieve complete combustion.

(2) The combustion tube 9, the intermediate ring 7, the swirl tube 6, and the center portion C of the bottom plate 3 are all in a negative pressure region due to the forced swirl flow along the wall surface.

Therefore, a phenomenon of reverse flow is observed in the stagnation area, and particularly high-temperature combustion heat circulates, improving combustion characteristics and stabilizing the combustion flame.

(3) Since the diameter of the intermediate ring 7 is made larger in steps than the diameter of the rotating tube 6, the flow stagnates at the edge portion a where the diameter changes, creating a negative pressure region, which acts to attract combustion flames. This will improve flame stability.

(4) If it is necessary to increase the atomization flow rate and increase the rotation angle of combustion air, it is necessary to increase the axial component airflow from the air port 4 near the blade 5 toward the combustion tube 9 side. There is a risk that the flame will become stronger and blow out from the upper part of the rotating cylinder 6.

Therefore, if necessary, a partition plate 8 forming a diaphragm having a diameter equal to or smaller than the diameter of the end face of the blade 5 on the central axis side is interposed between the intermediate ring 7 and the rotating airflow.

This promoted stagnation, flow circulation, and circularity on the downstream side of the air flow near the partition plate 8, and ensured flame stability.

(5) If it is necessary to reduce the atomization flow rate and restrict the amount of air, the degree of rotation of the air will inevitably decrease, and the concentration of particles in the air will also become diluted, slowing down the flame propagation. It exhibits the phenomenon of blowing out.

Therefore, a flame stabilizing plate 16 was provided on the upstream side of the airflow with respect to the atomization surface 13 facing the intermediate ring 7, and flame stabilization was completed in the negative pressure region generated downstream of the flame stabilizing plate 16.

(6) As mentioned in (4) and (5) above, by providing the partition plate 12 and the flame stabilizing plate 17 regardless of the atomization flow rate, a wide range of fuel flow rates can be handled, and the intermediate ring 7 It is possible to provide multiple atomization nozzles.

In addition, the reason why the atomized particles are scattered almost perpendicularly to the overall flow direction of the air flow is that it is expected that the mixing of the particles of the combustion air will be promoted by the hole action, and this effect is expected. is difficult to obtain with a mixing method that scatters atomized particles in the same direction as the air flow.

(7) The size of the negative pressure region at c is determined by the rotation angle and the combustion tube 9.
This is due to the size of the orifice, and by constricting the combustion tube 9 to at least the same diameter as or smaller than the diameter of the swirl tube 6, a vortex of the flow is generated at the edge portion in the figure to improve flame stability.

Further, the negative pressure region changes in proportion to the size of the throttle of the combustion tube 9, and forms a columnar negative pressure zone exactly at the center C.

Therefore, the combustion flame forms a columnar flame with a hollow center and close to the diameter of the orifice of the combustion tube.

However, since the columnar flame is surrounded by an annular air layer due to swirling, the wall surface of each cylindrical body is thermally shielded and there is no problem in terms of heat resistance.

(8) Even with a high-pressure spray nozzle that exhibits an atomization pattern, the atomization angle changes depending on the amount of fuel supplied, and the particle velocity may vary depending on the vibration amplitude and pressure. By arbitrarily changing the angle at which the atomization nozzle is attached to the wall surface, the atomized particle group can be appropriately sheared with air to promote mixing.

(9) As mentioned above (there is no problem because the wall surface of each cylindrical body is thermally isolated by the annular air layer, but such an effect cannot be expected for the bottom plate 3, so as mentioned above, the bottom plate 3 A refractory material 1 is placed on the top surface to isolate the bottom plate 3 from heat.

That is, each mechanism should be completely thermally shut off, so its lifespan will be significantly extended.

(10 A drain pipe 2 is provided in the center of the bottom plate 3 to drain the condensate of particles that have become uncombustible due to excessive fuel delivery and unignited fuel from the combustion device to the outside. Safety is ensured by releasing it.

In addition, in the embodiment, the case where an ultrasonic atomizer is used and the fuel particles atomized and scattered from the atomization surface are combusted is described, but the case where the fuel particles atomized from a pressure-type atomizer are combusted is also described. Also, it is possible to obtain almost the same effect as this embodiment.

As described above, the combustion apparatus of the present invention has the advantage that the atomized particles and air can be mixed in an optimal state for combustion, and the combustion is extremely stable.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a combustion device in an embodiment of the present invention;
FIG. 2 is a sectional view taken along the line XX in FIG. 1. 1... Fireproof material, 2... Drain pipe,
3...Bottom plate, 4...Air vent, 5...
...Swivel vane, 6...Swivel tube, 7...
・Intermediate ring, 8...Partition plate, 9...
Combustion tube, 12... Ultrasonic atomizer, 13...
...Atomization surface, 14...Fuel supply amount, 15...
...Blower tube, 16...Flame holding plate.

Claims (1)

[Scope of Claims] 1. A cylindrical combustion chamber having air swirling means at its lower part, with one or more fuel atomizing nozzles facing downstream of said swirling means, and said swirling nozzle on the open side of said combustion chamber. A combustion device characterized in that a combustion tube is provided with a diameter equal to or smaller than the diameter of the means forming part. 2. The combustion device according to claim 1, wherein the diameter of the swirl cylinder that forms the lower part of the cylindrical combustion chamber is smaller than the diameter of the cylinder that forms the upper part of the combustion chamber, and the fuel atomization nozzle faces the inner surface. . 3. The combustion device according to claim 2, wherein a partition member having a diameter smaller than the diameter of the rotating tube is provided between the rotating tube and the cylindrical body. 4. The combustion device according to claim 2 or 3, wherein a flame-holding plate is provided on the inner wall of the cylinder facing the fuel atomizing nozzle on the upstream side of the swirling air and close to the nozzle. . 5 The mounting angle of the nozzle facing the inner surface of the cylindrical combustion chamber is
The combustion apparatus according to any one of claims 1 to 4, which is configured to be arbitrarily set in accordance with the swirling strength of air. 6. The combustion device according to any one of claims 1 to 5, wherein a bottom plate having a drain pipe is provided at the center of the bottom of the combustion chamber, and a refractory material is provided on the top of the bottom plate.