JPS5875610A - Combustion apparatus for liquid fuel - Google Patents

Abstract

PURPOSE:To perform good combustion without noise in the titled apparatus, by stably evaporating liquid fuel, as well as to inhibit formation of tar, by making the botttom of a combustion chamber of a material having a heat conductivity and a heat-resistant property. CONSTITUTION:Fine particles of kerosene, collided against an inner cylinder 12, are evaporated by transferred heat from a flame stabilizer formed in the inner cylinder 12. While, kerosene dropped to the bottom 13 of a combustion chamber can immediately be evaporated because a metal material 16, out of which the bottom 13 of a combustion chamber is made, is heightened up to about 320 deg.C or thereabout by heat exchange conducted between transferred heat from the inner cylinder 12 and combustion air. With such an arrangement, tar is inhibited from being formed, and fine particles of kerosene are nearly uniformly evaporated between the inner cylinder 12 and an auxiliary combustion cylinder 15. In addition, combustion noise can be lowered, along with well stabilized flames can be formed on air injection ports 14 in the upper part of an inner cylinder 12, since the balance of air/fuel ratio is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid fuel combustion device used in a boiler or instantaneous water heater of a small domestic hot water supply or heating device.

Conventionally, this type of liquid fuel combustion apparatus includes an atomizing means 6 for atomizing and injecting liquid fuel into a combustion chamber 6, as shown in FIG.
At the time of ignition, it burns with a bright flame, and then the subsequent particulates are vaporized by the combustion heat, promoting diffusion and mixing. The vaporization-diffusion type combustion equipment, which produces a flame and performs flame-holding combustion, has the following drawbacks.

1. Since vaporization and diffusion takes place in the flame stabilizing flame hole portion of the air jet hole 14, if the mixing balance between fuel and air is disrupted even slightly, unburnt components are discharged and an odor is generated.

2. At the part where the fuel particles collide at a position away from the flame forming part, the fuel adheres and becomes droplets, forms a film-like liquid stream on the side wall of the middle cylinder 12, flows downwind, and accumulates in the bottom part 13 of the combustion chamber. Then, soot is generated during ignition, and during steady combustion, it is vaporized by convection heat in the combustion chamber 5 and heat transferred from the middle cylinder 12 to generate tar, which clogs the air jet hole 14 on the side wall of the middle cylinder 12. There are disadvantages in that flame holding becomes unstable due to unevenness in the amount of vaporization and fluctuations in the air-fuel mixture ratio, leading to factors such as combustion noise and failure to obtain good combustion characteristics.

The present invention provides liquid fuel atomization means facing into the combustion chamber from an opening provided in a bottomed cylindrical wall of the combustion chamber, and a large number of air injection holes in the side wall in the center of the combustion chamber. An auxiliary combustion cylinder having an opening facing the atomizing means is provided between the middle cylinder and the combustion chamber wall, and the bottom of the combustion chamber has thermal conductivity and heat resistance. The above-mentioned drawbacks of the prior art are overcome by constructing the device using a metal material having the following characteristics.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

Note that the same members as in the conventional example will be described with the same reference numerals.

In FIGS. 1 and 2, reference numeral 1 denotes an oil pipe for sending kerosene used as an example of liquid fuel, one end of which is connected to a fuel tank (not shown), and a fuel pump 2 for sending kerosene under pressure installed in the middle. Furthermore, an atomizer 6 used as an example of atomization means is provided at the other end, and faces into the combustion chamber 5 through an opening 4 provided in the combustion chamber wall 3. Reference numeral 7 designates a support 1 that constitutes a part of the combustion chamber wall 3 and holds the atomizer 6 and the ignition device 8 shown in FIG. Reference numeral 9 denotes a can body composed of an inner body 1o and an outer body 11, and forms a part of the combustion chamber 5.

12 is a middle cylinder provided almost in the center of the bottom part 13 of the combustion chamber;
A large number of air ejection holes 14 are provided along the outer peripheral wall in a tangential direction. Reference numeral 15 denotes an auxiliary combustion tube provided between the middle tube 12 and the combustion chamber wall 3 and the inner body 10 that constitutes the combustion chamber 6. The auxiliary combustion tube 15 and the middle tube 12 forcefully mix kerosene particles and vaporized gas. Premixing region [air-fuel ratio <o,
4]. A metal material 16 is provided at the bottom 13 of the combustion chamber, and is made of a material with excellent thermal conductivity and heat resistance, such as aluminum alloy (ADC12).

17 is an opening provided in the auxiliary combustion tube 15 facing the atomizer 6, through which the spray injected from the atomizer 6 flows into the auxiliary combustion tube 1.
5, and a large number of holes 18 are provided around the bottom 13 of the combustion chamber.

19 is a motor 20. Fan 21. This is a blower device composed of a fan case 22, which supplies combustion air to the middle cylinder 12 via the wind cylinder 23. 24 is a combustion ring that controls the pressure within the combustion chamber 6, the flow of combustion gas, and the amount of recirculation of combustion gas.

In the liquid fuel combustion device configured in this way, when the motor 2o, which is the blower device 19, is energized, combustion air is supplied to the middle cylinder 12 through the wind cylinder 23, and is ejected from the air jet hole 14 into the combustion chamber 6. be done. After the blower device 19 operates, the ignition device 8 is energized to generate sparks after a certain time delay, and then pressurized kerosene is pumped from the atomizer 6 into the premixing region in the combustion chamber 5 by the operation of the fuel pump 2. is sprayed on.

Combustion air of a certain amount or less (air-fuel ratio (0, 4) with respect to this spray amount is ejected from the lower air injection hole 14 of the middle cylinder 12,
Particulates and combustion air mix in the middle cylinder 12, the auxiliary combustion cylinder 16, and the combustion chamber 5 at the bottom, and when a certain mixing ratio is reached, the ignition device 8 ignites the mixture. After ignition, the vaporization of the subsequent fine particles is further promoted by receiving radiant heat etc. from the bright flame, and they move to the upper part of the middle cylinder 12 in a highly concentrated premixed state. The premixture that has moved to the upper part of the middle cylinder 12 is
Combustion air is taken in from the air blow-off holes 14 provided at the upper part of the middle cylinder 12 and changes into a non-bright flame (blue flame), forming a swirling flame in each air blow-out hole 14 at the upper part of the middle cylinder 12. This is middle tube 12
The air jet holes 14 are arranged tangentially along the outer peripheral wall of the
This is because it is provided. Thereafter, as the temperature within the combustion chamber 6 rises, the particles in the premixed gas are rapidly vaporized and mixed.

The fine particles of kerosene that collided with the middle cylinder 12 are vaporized by heat transfer from the flame holding part formed in the middle cylinder 12, and the kerosene that has flowed to the bottom 13 of the combustion chamber is caused by the metal material 16 of the bottom 13 of the combustion chamber. The temperature is about 320° C. due to heat transfer from the middle cylinder 12 and heat exchange with the combustion air, so it can be vaporized quickly. Therefore, generation of tar is suppressed.

, and the air-fuel ratio balance is stable.
Good flame stability is formed in the air injection holes 14 of the middle cylinder 12-F portion, and combustion noise can be reduced.

Furthermore, if the surface roughness of the metal material 16 provided at the bottom 13 of the combustion chamber is set to Rmax = 100 to 30 microns, the maximum evaporation temperature Ta of kerosene is determined as shown by curve a in Figure 3.
is 320° C., which is the minimum evaporation time of kerosene (1), and the temperature of the metal material 16 necessary for this evaporation can be obtained by heat transfer from the middle cylinder 12 and heat exchange with combustion air.

In addition, the curved line is the surface roughness of the metal material Rmax-300
~400 microns, Curve C shows the evaporation characteristics of kerosene with the surface of the metal material polished. .

Therefore, liquefied kerosene does not accumulate at the bottom 13 of the combustion chamber and tar is not generated, and better combustion characteristics can be obtained.

Furthermore, if a composite oxide containing alumina is welded to the surface of the metal material 16 provided at the bottom 13 of the combustion chamber, a heat exchange section is formed together with the heat transfer by the air, and the temperature becomes about 320.degree.

On the other hand, as shown by curve d in FIG. 4, the evaporation time (1) near the maximum evaporation point Td of kerosene forms a gentle curve over a wide range of temperatures.

Note that curve a is the surface roughness of the metal material Rmax = 100
The evaporation characteristics of kerosene in a state of ~3oO microns are shown.

Therefore, characteristics close to the minimum evaporation time of kerosene can be obtained without being greatly affected by temperature changes at the bottom 13 of the combustion chamber.Moreover, since the contact area between kerosene and the bottom 13 of the combustion chamber is increased, nuclear film boiling allows the kerosene to evaporate faster. evaporates.

Since it is vaporized, good combustion can be achieved without generating tar.

As is clear from the above description, the liquid fuel combustion device of the present invention has the bottom part of the combustion chamber made of a metal material having thermal conductivity and heat resistance, so that generation of tar is suppressed and stable liquid fuel can be vaporized, resulting in extremely good combustion with no noise during combustion.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a liquid fuel combustion device showing an embodiment of the present invention, Fig. 2 is a plan sectional view taken along the line AA' in Fig. 1, and Figs. 3 and 4 show liquid fuel combustion equipment. FIG. 6 is a side sectional view of a conventional liquid fuel combustion device. 4...Opening, 6...Combustion chamber, 6...
... Atomizer (atomization means), 12 ... Middle cylinder,
15... auxiliary combustion tube, 16... metal material. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 12 Fig. 3 Fig. 14 Fig. 7 L/1 S Figure Procedure Amendment I Incident Display 1982 Patent Application No. 173603 2 Name of Invention Liquid Fuel Combustion Apparatus 3 Supplementary JF Person A'1. ! : Relationship Patent Application Address 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture
Address Name (582) Representative of Matsushita Electric Industrial Co., Ltd.
Toshihiko Yamashita 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture - Matsushita Electric Industrial Co., Ltd. Specification 1 Name of the invention Liquid fuel combustion device 2 Claims (1) Bottomed cylinder a combustion chamber having a shape, an opening provided in the wall of the combustion chamber, an atomizing means for atomizing and atomizing liquid fuel by exposing the opening into the combustion chamber, and a bottom part of the combustion chamber located approximately in the center of the combustion chamber. an auxiliary combustion cylinder that stands upright and has a large number of air ejection holes on its side wall; and an auxiliary combustion cylinder that is provided between the middle cylinder and the AiJ combustion chamber wall and has an opening at a position facing the atomization means. A liquid fuel combustion device comprising: a bottom portion of the combustion chamber made of a metal material having thermal conductivity and heat resistance. (2) The liquid fuel combustion device according to claim 1, wherein the surface of the metal material is roughened. (3) The liquid fuel combustion device according to claim 1, wherein a composite acid oxide containing alumina is welded to the surface of the metal material. 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a liquid fuel combustion device used in boilers or instantaneous water heaters for small domestic hot water supply and heating systems. Structure of conventional example and its problems Conventionally, this type of liquid fuel combustion apparatus has an atomizing means 6 for atomizing and injecting liquid fuel into a combustion chamber 5, as shown in FIG.
At the time of ignition, it burns with a bright flame, and then the subsequent particulates are vaporized by the heat of combustion, promoting diffusion and mixing. The vaporization-diffusion type combustion equipment, which produces a bright flame and performs flame-holding combustion, has the following drawbacks. 1. Since combustion occurs while promoting further diffusion and mixing in the flame-holding flame hole portion of the air jet hole 14, if the mixing balance between fuel and air is disrupted even slightly, unburned components are discharged and generate odor. 2. At the part where the fuel particles collide at a position away from the flame forming part, the fuel adheres and becomes droplets, forms a film-like liquid stream on the side wall of the middle cylinder 12, flows downwind, and accumulates in the bottom part 13 of the combustion chamber. Then, soot is generated during ignition, or tar is generated by convection heat in the combustion chamber 5 or heat transfer from the middle cylinder 12 during steady combustion, and the soot is blown into the air jet hole 14 on the side wall of the middle cylinder 12. This causes unevenness in the amount of vaporization and fluctuations in the air-fuel mixture ratio, making flame holding unstable, leading to factors such as combustion noise, and having the disadvantage that good combustion characteristics cannot be obtained. OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional art, and provides a liquid fuel combustion device that can always achieve stable vaporization of liquid fuel, generate very little noise even during combustion, and achieve good combustion conditions. The purpose is to SUMMARY OF THE INVENTION In order to achieve the above object, the liquid fuel combustion device of the present invention has a liquid fuel combustion apparatus that injects liquid fuel into the combustion chamber from an opening provided in a bottomed cylindrical combustion chamber wall. In addition to facing the atomization means, a middle cylinder having a large number of air injection holes on the side wall is provided in the center of the combustion chamber, and an opening facing the atomization means is provided between the middle cylinder and the combustion chamber wall. The present invention solves the above-mentioned drawbacks of the conventional combustion chamber by providing a combustion auxiliary cylinder having a section, and by constructing the bottom of the combustion chamber from a metal material having thermal conductivity and heat resistance. DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. Note that the same members as in the conventional example will be described with the same reference numerals. In FIGS. 1 and 2, reference numeral 1 denotes an oil pipe for sending kerosene used as an example of liquid fuel. One end is connected to a fuel tank (not shown), and a fuel pump 2 for pumping kerosene is provided in the middle. Further, at the other end, an atomizer 6 used as an example of atomization means is provided, which faces into the combustion chamber 6 through an opening 4 provided in the combustion chamber wall 3. Reference numeral 7 denotes a support cylinder that constitutes a part of the combustion chamber wall 3 and holds the atomizer 6 and the ignition device 8 shown in FIG. Reference numeral 9 denotes a can body composed of an inner body of 1Ω and an outer body 11, which forms a part of the combustion chamber 5, and the inner body 10 forms the combustion chamber wall 3. 12 is a middle cylinder provided almost in the center of the bottom part 13 of the combustion chamber;
A large number of air ejection holes 14 are provided along the outer peripheral wall in a tangential direction. Reference numeral 15 denotes an auxiliary combustion tube provided between the middle tube 12 and the combustion chamber wall 3 and the inner body 1o constituting the combustion chamber 5. The auxiliary combustion tube 15 and the middle tube 12 forcefully mix kerosene particles and vaporized gas. Premixing area where air holes < 0
．． 4] is formed. Reference numeral 16 denotes a metal material provided at the bottom 13 of the combustion chamber, such as aluminum alloy (ADCl 2
) and other materials with excellent thermal conductivity and heat resistance. 17 is an opening provided in the auxiliary combustion tube 15 facing the atomizer 6, through which the spray injected from the atomizer 6 flows into the auxiliary combustion tube 1.
5, and a large number of holes 18 are provided around the bottom 13 of the combustion chamber. 19 is a motor 20. A fan 21.7' is a blowing device composed of an anchor 22, which supplies combustion air to the middle cylinder 12 via the wind cylinder 23. 24 is a combustion ring that controls the pressure within the combustion chamber 5, the flow of combustion gas, and the amount of recirculation of combustion gas. In the liquid fuel combustion device configured in this manner, when the motor 2o, which is the blower device 19, is energized, combustion air is supplied to the middle cylinder 12 through the wind cylinder 23, and is ejected from the air jet hole 14 into the combustion chamber 5. be done. After the blower device 19 operates, the ignition device 8 is energized to generate sparks after a certain time delay, and then pressurized kerosene is pumped from the atomizer 6 into the premixing region in the combustion chamber 5 by the operation of the fuel pump 2. is sprayed on. Combustion air of a certain amount or less (air ratio <0.4) with respect to this spray amount is ejected from the lower air injection hole 14 of the middle cylinder 12,
Kerosene particles and combustion air are mixed in the middle cylinder 12, the auxiliary combustion cylinder 15, and the lower part of the combustion chamber 5, and when a certain mixing ratio is reached, the ignition device 8 ignites the mixture. After ignition, the vaporization of the subsequent kerosene particles is further promoted by receiving radiant heat from the bright flame, and the particles move to the upper part of the middle cylinder 12 in a highly concentrated premixed state. The premixture that has moved to the upper part of the middle cylinder 12 takes in combustion air from the air jet hole 14 provided at the upper part of the middle cylinder 12 and changes into a non-bright flame (blue flame). A swirling flame is formed at each air outlet 14. This is because the air vent holes 14 are provided along the outer peripheral wall of the middle cylinder 12 in a tangential direction. Thereafter, as the temperature within the combustion chamber 5 rises, the particles in the premixed gas are rapidly vaporized and mixed. The particulates of kerosene that collided with the middle cylinder 12 are vaporized by heat transfer from the flame holding part formed in the middle cylinder 12, and the kerosene that has flowed down to the bottom part 13 of the combustion chamber that has broken off is The metal material 16 reaches a temperature of about 320'C due to heat transfer from the middle cylinder 12 and heat exchange with the combustion air, so it can be quickly vaporized. Therefore, generation of tar is suppressed. Furthermore, fine particles of kerosene are vaporized almost uniformly between the middle cylinder 12 and the auxiliary combustion cylinder 16, and the air-fuel ratio balance is stable, so that good flame stability is formed in the air nozzle hole 14 in the top part of the middle cylinder 12. If the surface roughness of the metal material 16 provided on the bottom 13 of the combustion chamber is set to Fknax = 100 to 30 microns, the sum of 81, the curve a in Figure 3 can be achieved. As shown in the figure, the evaporation temperature Ta at the maximum evaporation point of kerosene is 320'C, which is the minimum evaporation time of kerosene.The temperature of the metal material 16 required for this evaporation is determined by the heat transfer from the middle cylinder 12 and the heat generated by the combustion air. It can be obtained by exchanging the curve with the surface phase of the metal material Rmax -30
0 to 400 microns, curve C shows the evaporation characteristics of kerosene when the surface of the metal material is polished. Therefore, liquefied kerosene does not accumulate at the bottom 13 of the combustion chamber and tar is not generated, and better combustion characteristics can be obtained. Furthermore, if a composite oxide containing alumina is welded to the surface of the metal material 16 provided at the bottom 13 of the combustion chamber, heat transfer from the flame holding part formed in the middle cylinder 12 and heat transfer by combustion air can be achieved. At the same time as forming the exchange part, the temperature is about 320'
It is maintained around C. - As shown in curve d in Figure 4, the evaporation time t near the maximum evaporation point Td of kerosene forms a gentle curve over a wide range of temperatures. Note that the curve a is the sum of the surface of the metal material Rmax = 1
to○1iffaH58-75610(7) Shows the evaporation characteristics of kerosene in a state of ~300 microns. Therefore, characteristics near the minimum evaporation time of kerosene can be obtained without being affected by temperature changes at the bottom 13 of the combustion chamber. Moreover, since the contact area between the kerosene and the bottom 13 of the combustion chamber is increased, the kerosene evaporates and vaporizes more quickly due to double boiling of the core or film, so that good combustion can be achieved without generating tar. Effects of the Invention As is clear from the above explanation, the liquid fuel combustion device of the present invention has the bottom part of the combustion chamber made of a metal material having thermal conductivity and tetrathermal properties, so that generation of tar is suppressed and stable. The liquid fuel can be vaporized, resulting in extremely good combustion without noise during combustion. 4. Brief description of the drawings Fig. 1 is a vertical sectional view of a liquid fuel combustion device showing one embodiment of the present invention, Fig. 2 is a plan sectional view at A, A/pure of Fig. 1, and Fig. 3 , Fig. 4 is a diagram showing the evaporation characteristics of liquid fuel and kerosene used in (7), and Fig. 5 is a side sectional view of a conventional example of a liquid fuel combustion device with 7J<0. , 5... Combustion chamber, 6...
... Atomizer (atomization means), 12 ... Middle cylinder, 15 ... auxiliary combustion cylinder, 16 ... Metal material.

Claims (1)

[Scope of Claims] (1) A cylindrical combustion chamber with a bottom, an opening provided in the wall of the combustion chamber, and atomization in which liquid fuel is atomized and atomized by facing into the combustion chamber from this opening. means, a middle cylinder that stands upright at the bottom of the combustion chamber and has a number of air injection holes on its side wall; and a middle cylinder that is provided between the middle cylinder and the wall of the combustion chamber;
A liquid fuel combustion device comprising an auxiliary combustion tube having an opening at a position facing the atomization means, and a bottom of the combustion chamber made of a metal material having thermal conductivity and heat resistance.゛(2)
The liquid fuel combustion device according to claim 1, wherein the surface of the metal material is roughened. (3) The liquid fuel combustion device according to claim 1, wherein a composite acid substitute containing alumina is welded to the surface of the metal material.