JP2843175B2 - Liquid fuel combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The invention of claims 1 and 2
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fuel combustion apparatus for preliminarily mixing vaporized liquid fuel with combustion air for combustion.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a combustor of a conventional liquid fuel combustion apparatus disclosed in Japanese Utility Model Publication No. 58-21378, for example. In the figure, 1 is a vaporization chamber for vaporizing liquid fuel, 2 is an electric heater buried in the side wall of the vaporization chamber 1 and heats the vaporization chamber 1, and 3 is a throttle fitted and fixed to the upper part of the vaporization chamber 1. Reference numeral 4 denotes a burner head provided on the throttle unit 3 and a plurality of flame holes 5 provided on a side wall. Reference numeral 6 denotes a wire mesh closely wound around the outer peripheral surface of the burner head 4. Reference numeral 7 denotes a burner head. 4 is a cap which covers the upper part, 8 is a special screw for fixing the burner head 4 and the cap 7 to the throttle unit 3, one end of which is embedded in the throttle unit 3, 9 is a burner head 4.
A mixing plate having a plurality of holes in its bottom surface,
Is an annular flame holding ring attached to the upper part of the vaporizing chamber 1 so as to surround the burner head 4.

[0003] Reference numeral 11 denotes a nozzle fixed to the side wall of the vaporization chamber 1 and opening into the vaporization chamber 1. This nozzle 11 is connected to an air supply pipe (not shown) communicating with a blower (not shown). Have been. The nozzle 11 has an inlet 11a, a tapered portion.
11b and a throat 11c. Reference numeral 12 denotes a fuel supply pipe for supplying liquid fuel from a fuel tank (not shown) to the vaporization chamber 1.
12a is arranged coaxially with the nozzle 11 so as to protrude from the throat portion 11c.

Next, the operation will be described. By energizing the electric heater 2, the vaporization chamber 1 is preheated to a temperature (200 to 300 ° C.) necessary for vaporizing the liquid fuel. After the completion of the preheating, the combustion air sent from the blower to the air supply pipe is supplied from the nozzle 11 to the vaporization chamber 1. Further, from the fuel supply pipe 12, liquid fuel is supplied to the vaporization chamber 1 in such an amount that the air ratio (= supply air amount / theoretical air amount) becomes about 0.8.

[0005] The supplied liquid fuel is atomized by the shear force of the combustion air, and is vaporized on a preheated vaporized surface.
The vaporized liquid fuel (combustion gas) is supplied to the throttle section 3, the mixing plate 9
When passing through the air, it is further premixed with the combustion air to make the concentration distribution uniform. Thereafter, the combustion gas is ignited by the ignition device (not shown) on the flame hole 5 of the burner head 4,
A primary flame 14 and a secondary flame 15 are formed. After the start of combustion,
Since the vaporization chamber 1 is heated by the heat recovery from the flame by the flame holding ring 10 or the like, the input to the electric heater 2 becomes unnecessary.

FIG. 5 shows, for example, Japanese Patent Publication No. 58-3869.
FIG. 2 is a configuration diagram showing another conventional liquid fuel combustion device disclosed in Japanese Patent Publication No. 0-0. In the figure, reference numeral 21 denotes a first air supply pipe to which the nozzle 11 is connected at the tip, and 22 denotes a first air supply pipe.
A second air supply pipe branched from 21 and having a tip inserted into the vaporization chamber 1 from the bottom is provided at a branch of the first and second air supply pipes 21 and 22 to provide combustion air. Is diverted to the second air supply pipe 22 at a predetermined ratio, and the cock 23 also serves as an input control cock.

[0007] Reference numeral 24 denotes a constant oil level gauge connected to a fuel tank (not shown) via a pipe 25.
A base end of the fuel supply pipe 12 is provided in the oil level of the fuel supply pipe. Reference numeral 26 denotes a constant oil level gauge 24 for controlling the static air pressure at the inlet 11a of the nozzle 11.
It is a static pressure pipe introduced into the upper space inside. The other parts are the same as those in FIG.

In the liquid fuel combustion device shown in FIG.
Combustion air is blown to the first air supply pipe 21 by a blower (not shown). The blown combustion air is distributed to the first air supply pipe 21, the second air supply pipe 22, and the static pressure pipe 26. This input is adjusted by the cock 23. Thus, in addition to the first air supply pipe 21, the second air supply pipe 22
Is provided, the air ratio is always constant with respect to fluctuations in environmental conditions, and an appropriate combustion state is maintained.

FIG. 6 is a graph showing the flow rate characteristics of the cock 23 shown in FIG. As shown in this figure, by turning the knob, the input changes substantially in proportion to the angle of the knob, and the primary air ratio μ becomes substantially constant within the use range. For this reason,
By turning the knob of the cock 23, it is possible to easily adjust the heating power without changing the air ratio.

[0010]

In the conventional liquid fuel combustion apparatus constructed as described above, the one shown in FIG. 4 uses the nozzle 11 to atomize the liquid fuel at the tip of the nozzle 11. Must be increased, which causes jet noise (Air-Jet sound). The combustion noise is obtained by amplifying the jet noise at the nozzle 11 by the flame. If the jet noise is reduced, the combustion noise can be reduced.

In order to reduce the jet noise, the flow rate or flow velocity of the combustion air passing through the nozzle 11 may be reduced. However, since the amount of primary air required for combustion is determined, the amount of air passing through the nozzle 11 is determined. Can not be reduced. Also,
If the flow rate is reduced by increasing the diameter of the nozzle 11 without changing the flow rate, the blowing pressure to the nozzle 11 decreases, so that particles having a large particle diameter intermittently fly out, and the atomization characteristics of the liquid fuel Gets worse. In particular, when the power is low, the fuel is not sufficiently mixed with the combustion air, or the flame generates a strong pulsation, so that the combustion variable range is narrowed. Thus, the apparatus of FIG. 4 has a problem that the combustion noise cannot be reduced without impairing the atomization characteristics of the liquid fuel.

On the other hand, also in the apparatus shown in FIG. 5, since the second air supply pipe 22 is not provided for the purpose of noise reduction, the jet noise at the nozzle 11 is the same as that shown in FIG. There is a problem that noise is generated in the same manner as in FIG.

SUMMARY OF THE INVENTION The first and second aspects of the present invention have been made to solve the above problems, and reduce jet noise during air supply without narrowing a variable range of a combustion amount. It is an object of the present invention to obtain a liquid fuel combustion device which can reduce combustion noise by this.

[0014]

According to a first aspect of the present invention, there is provided a liquid fuel combustion apparatus, comprising:
The diameter is larger than the diameter of the tip of the first air supply pipe for atomizing the liquid fuel.

In the liquid fuel combustion apparatus according to the present invention, the diameter of the tip of the second air supply pipe is made larger than the diameter of the tip of the first air supply pipe for atomizing the liquid fuel. In addition, the first and second air supply pipes are opened tangentially to the side wall of the vaporization chamber so that the supplied combustion air turns in the same direction in the vaporization chamber.

[0016]

According to the first aspect of the present invention, the diameter of the tip of the first air supply pipe is reduced by increasing the diameter of the tip of the second air supply pipe. Reduce air flow while maintaining air flow velocity.

In the second aspect of the invention, the diameter of the tip of the first air supply pipe is reduced by increasing the diameter of the tip of the second air supply pipe. By reducing the air flow rate while maintaining the air flow velocity and swirling the combustion air in the vaporization chamber, the residence time of the combustion air is lengthened, and the concentration distribution of the mixed gas of the combustion air and the vaporized liquid fuel is improved. Make uniform.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; FIG. 1 is a block diagram showing a liquid fuel combustion apparatus according to an embodiment of the present invention. The same or corresponding parts as those in FIGS. 4 and 5 are denoted by the same reference numerals, and description thereof will be omitted. In the figure, 31 is provided between the vaporization chamber 1 and a blower (not shown) to supply combustion air to the vaporization chamber 1 and to atomize the liquid fuel discharged from the fuel supply pipe 12. The first air supply pipe 31 has a first end which is opened at a side wall of the vaporization chamber 1.
Nozzle 32 is provided. In addition, the first nozzle 32
Has a first inlet portion 32a, a first tapered portion 32b, and a first throat portion 32c having a smaller diameter than that of the conventional example. Further, the fuel supply port 12a at the tip of the fuel supply pipe 12 is
The nozzle 32 is coaxially arranged so as to protrude from the throat portion 32c.

Reference numeral 33 denotes a second air supply pipe which is branched from the first air supply pipe 31 and supplies combustion air to the vaporization chamber 1. A second nozzle 34 is provided on the side wall of the vaporizing chamber 1.
The second nozzle 34 includes a second inlet portion 34a, a second tapered portion 34b, and a second throat portion 34c. Further, the diameter of the second throat portion 34c is larger than the diameter of the first throat portion 32c.

Reference numeral 35 denotes a constant oil level gauge connected to a fuel tank (not shown) through a pipe 36.
A base end of the fuel supply pipe 12 is provided in the oil level of the fuel supply pipe. Further, a static pressure pipe 26 is connected between the constant oil level unit 35 and the first nozzle 32. 37 is a pump for sending liquid fuel into the constant oil level unit 35.

Next, the operation will be described. When the temperature of the vaporizing chamber 1 reaches a predetermined temperature, the same amount of combustion air as in the conventional case is blown from the blower. The blown combustion air is distributed to the first air supply pipe 31 and the second air supply pipe 33. First
When the combustion air in the air supply pipe 31 is supplied from the first nozzle 32 to the vaporization chamber 1, the combustion fuel atomizes the liquid fuel.

The combustion air in the first air supply pipe 31 is
The amount of air flow in the first throat portion 32c is the same as that of the conventional one because the diameter of the first throat portion 32c is smaller than that of the conventional one. Therefore, the shearing force of the combustion air is the same as before, and the atomization characteristics of the liquid fuel do not deteriorate. On the other hand, the combustion air in the second air supply pipe 33 is ejected from the second nozzle 34 having a larger diameter than the first nozzle 32 into the vaporization chamber 1.
The flow velocity of the combustion air passing through the throat portion 34c is small.

As for the supplied liquid fuel, the static pressure of the blast generated in the first nozzle 32 is applied through the static pressure pipe 26, so that the pressure difference between the static pressure of the blast and the internal pressure of the vaporization chamber 1 is reduced. The corresponding fuel amount is supplied to the vaporization chamber 1 from the fuel supply port 12a. The liquid fuel injected into the vaporization chamber 1 is vaporized on the preheated vaporization surface, and is mixed with the combustion air in the vaporization chamber 1 to become a premixed gas. The premixed gas is supplied to the throttle unit 3 and the mixing plate 9.
And a primary flame 14 and a secondary flame 15 are formed on the flame hole 5 of the burner head 4.

In such a liquid fuel combustion apparatus, the flow rate of air in the first air supply pipe 31 is reduced by the amount branched into the second air supply pipe 33. Noise is reduced. Further, since the diameter of the second nozzle 34 is increased to reduce the air flow velocity of the second air supply pipe 33, the jet noise of the second air supply pipe 33 is considerably reduced. Therefore, the overall combustion noise is reduced. In addition, since the air flow velocity of the first air supply pipe 31 is the same as the conventional one, the atomization characteristics of the liquid fuel are not impaired.

FIG. 2 is a sectional view of a main part of a liquid fuel combustion apparatus according to an embodiment of the present invention. In the figure, the first and second nozzles 32 and 34 are tangential to the side wall of the vaporization chamber 1 so that the supplied combustion air turns in the same direction along the inner wall surface in the vaporization chamber 1. It is open towards. The other parts are the same as in FIG.

In the apparatus shown in FIG. 2, a first air supply pipe is provided.
The combustion air from 31 is supplied to the vaporization chamber 1 via the first nozzle 32. Further, a shortage of combustion air is supplied from the second air supply pipe 33 to the vaporization chamber 1 through the second nozzle 34. At this time, the first and second air supply pipes 31,
33 are provided on the side wall of the vaporization chamber 1, so that the concentration distribution of the premixing of the combustion air and the combustion gas is lower than that in the case where both are provided on the bottom of the vaporization chamber 1 as shown in FIG. Is kept uniform, and the flame distribution is improved.

Further, since each combustion air is ejected in the same direction along the inner wall surface of the vaporization chamber 1 to form a swirling flow, the residence time in the vaporization chamber 1 becomes longer, and the concentration distribution of the premixing increases. Becomes even more uniform. In addition, the blowing from the second nozzle 34 does not weaken the shearing force of the first nozzle 32, the liquid fuel is finely atomized, and a stable flame is formed.

FIG. 3 is a graph showing an example of the results of an experiment conducted by the inventors and showing the relationship between the amount of combustion and the combustion noise. In this experiment,
The nozzle diameter of the conventional apparatus was φ8.8 mm, the nozzle diameter of the first nozzle 32 of the apparatus of the embodiment was φ5.0 mm, and the nozzle diameter of the second nozzle 34 was φ15.0 mm. In this experiment, the nozzle cross-sectional area of the first nozzle 32 was set to 1/3 of the conventional device.
Then, the remaining 2/3 is supplied from the second nozzle 34. In the apparatus of the embodiment, since the air flow velocity of the first nozzle 32 is the same as that of the conventional apparatus, the atomization characteristics and combustion distribution are not deteriorated, and the noise reduction of about 4 dB can be achieved.

When it is desired to change the amount of combustion during combustion, the first and second air supply pipes are controlled by the rotation speed of the blower.
What is necessary is just to change the air volume sent to 31,33. Then, with this, the pressure transmitted from the static pressure pipe 26 to the constant oil level unit 35 also changes, so that the ratio (air ratio) between the liquid fuel and the combustion air becomes almost constant irrespective of the combustion amount. The combustion state is maintained.

In each of the above embodiments, the second air supply pipe is used.
Although the one provided with the second nozzle 34 at the tip of 33 is shown,
It is also possible to provide a cylindrical tip portion whose diameter does not change without providing a throttle such as a nozzle. In each of the above embodiments, the combustion air from one blower is supplied to the first and second air supply pipes 31,
Although distributed to 33, a blower may be connected to each of the first and second air supply pipes 31 and 33 to control the amount of air respectively. Further, the arrangement positions of the first and second supply pipes 31 and 33 are not limited to the above embodiment, and may be, for example, positions as shown in FIG.

[0031]

As described above, in the liquid fuel combustion apparatus according to the first aspect of the present invention, the diameter of the tip of the second air supply pipe is reduced by changing the diameter of the first air supply pipe for atomizing the liquid fuel. Since the diameter of the first air supply pipe is larger than the diameter of the first air supply pipe, the diameter of the tip of the first air supply pipe can be made smaller than that of the conventional air supply pipe. In addition, the air flow velocity of the second air supply pipe can be reduced, and as a result, the jet noise during air supply can be reduced without narrowing the variable range of the combustion amount, thereby reducing the combustion noise. This has the effect.

Further, in the liquid fuel combustion apparatus according to the present invention, the diameter of the tip of the second air supply pipe is larger than the diameter of the tip of the first air supply pipe for atomizing the liquid fuel. At the same time, the first and second air supply pipes are opened tangentially to the side wall of the vaporization chamber so that the supplied combustion air turns in the same direction in the vaporization chamber.
In addition to the effect of the first aspect of the present invention, the residence time of the combustion air is lengthened, the concentration distribution of the mixed gas of the combustion air and the vaporized liquid fuel can be made uniform, and the liquid fuel is atomized. There is an effect that a stable flame can be formed without impairing the characteristics.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a liquid fuel combustion apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a liquid fuel combustion apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a combustion amount and a combustion noise showing noise characteristics in the conventional apparatus and the apparatus of the embodiment.

FIG. 4 is a sectional view of a combustor as an example of a conventional liquid fuel combustion device.

FIG. 5 is a configuration diagram showing another example of a conventional liquid fuel combustion device.

6 is a diagram showing the relationship between the amount of air, the amount of kerosene, the primary air ratio, and the knob angle of the cock showing the flow rate characteristics of the cock shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vaporization chamber 12 Fuel supply pipe 31 First air supply pipe 33 Second air supply pipe

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-55-53609 (JP, A) JP-A-4-332305 (JP, A) JP-A-2-45319 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) F23D 11/10

Claims (2)

(57) [Claims] 1. A vaporization chamber for vaporizing a liquid fuel, a fuel supply pipe for supplying the liquid fuel to the vaporization chamber, and a tip portion surrounding the fuel supply pipe, and supplying combustion air to the vaporization chamber. A first air supply pipe for atomizing liquid fuel discharged from the fuel supply pipe, and a diameter of a tip end part is larger than a diameter of a tip end part of the first air supply pipe; A second air supply pipe for supplying combustion air to the chamber. 2. A vaporization chamber for vaporizing a liquid fuel, a fuel supply pipe for supplying the liquid fuel to the vaporization chamber, and a tip portion surrounding the fuel supply pipe, and supplying combustion air to the vaporization chamber. A first air supply pipe for atomizing liquid fuel discharged from the fuel supply pipe, and a diameter of a tip end part is larger than a diameter of a tip end part of the first air supply pipe; A second air supply pipe for supplying combustion air to the chamber, wherein the first and second air supply pipes are configured such that the supplied combustion air turns in the same direction in the vaporization chamber. A liquid fuel combustion device, which is open to a tangential direction on a side wall of the vaporization chamber.