JPS58182019A - Burner for liquid fuel - Google Patents

Abstract

PURPOSE:To suppress the production of soot and tar and to sharply improve a combustion property, by a method wherein a flying direction and a jet position of fuel are adjusted by a means for controlling the quantity atomized for a given time of starting and through switching of a flow path switching valve. CONSTITUTION:With a motor 16 energized and a blowing mechanism operated, the air for combustion is fed to an intermediate cylinder 11, and is jetted in a specified ratio through each air jet hole 15 in the intermediate cylinder 11 to a premixing range (b) and then to a combustion range (a) in a combustion chamber 5. In this case, a flow path switching valve 3 for fuel interconnects a first vortex system jet valve 4 and a fuel pump 2. After the operation of the blowing mechanism delays by a specified time, an igniter 6 is energized to generate sparks. Simultaneously, a voltage applied to a fuel pump 2 is inputted for a given period of time as it is gradually adjusted, and as a result, liquid fuel, of which a voltage is gradually regulated, is atomized into the combustion chamber 5 from the vortex system jet valve 4 corresponding to a first atomizing means.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid fuel combustion device used as a heat source device of a small domestic hot water supply/heating device.

Conventionally, an atomization means is installed in the combustion chamber to cause diffusion combustion with a bright flame in the early stages of startup, and then the subsequent fuel particles are immediately vaporized at high speed by combustion heat, promoting diffusion mixing and achieving a partially premixed state. In a liquid fuel combustion device that performs flame-holding combustion in the air nozzle part, a stable flame is formed in the nozzle at the upper part of the middle cylinder by the amount of 1-tal air supplied from each nozzle on the middle cylinder. The following operations are performed. In other words, during the transient combustion period from ignition to steady combustion, there is a shortage of combustion air ejected from each nozzle in the middle and lower part of the middle cylinder, and there is a lack of fuel atomized by the atomization means. While diffusive combustion is being performed in a sufficiently mixed state, new air is supplied and swirls upward within the combustion chamber. As a result, the flame producing soot comes into contact with the surface of the inner cylinder, which is the center of the swirling flow within the combustion chamber, causing soot to adhere. By repeating such a transient combustion period, the attached soot grows and becomes layered. ! In addition, among the collision parts of flying fuel particles, at positions far from the flame formation part, fuel particles adhere and re-liquefy, and are evaporated and vaporized by the heat of combustion, so tar is generated on the collision part surface. , stick. In this way, the adhesion and growth of soot and tar near the air nozzle on the middle cylinder causes unevenness in the vaporization/diffusion mixture amount and mixture ratio during steady combustion, and increases combustion noise due to unstable flame holding. 1 Components of exhaust gas during ignition and extinguishing (especially Go
, He, etc.).

In view of the two drawbacks, the present invention aims to: (1) optimize the mixing ratio during the transient combustion period in the premixing region configured within the combustion chamber;
Promotion of mixing, ■ main components of fuel ejected particulates inside the vessel (%
(in the middle cylinder) and in steady combustion.■
The purpose is to ensure proper mixing.

In order to achieve the above object, the present invention reduces the amount of material atomized to less than the rated amount for a predetermined period of time during startup combustion.

In addition, the direction in which the atomized fuel particles are ejected is made to follow the flow direction (swirling flow) formed by the air ejected from the middle cylinder of the combustion chamber, and after that time, the rated atomization amount is achieved, and the atomization means is Specifically, a plurality of atomization means are used to deviate the injection direction or injection position of the fuel.
A fuel flow path switching valve is provided, and at least one of the fuel injection direction and the fuel injection position of each atomization means is made different.

- By using the structural acid mentioned above, it is possible to optimize the mixture ratio and promote mixing during the transient combustion period in the premixing region, and at the same time reduce the amount of fuel impingement on the main components in the combustion chamber (especially the middle cylinder). Since the area can be reduced, adhesion and growth of soot and tar can be suppressed.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, a fuel pump 2 and a fuel flow path switching valve 3 are connected to a fuel tank (not shown) via an oil feed vibrator 1. As shown in FIG. At the branched end downstream of the fuel flow switching valve 3, an atomization means and two spiral injection valves 4 are installed.
4' are connected to each other, and each fuel injection direction is provided at a constant angle of displacement θ□ and has an injection position x0.

Among these, the direction and position of fuel injection by the spiral injection valve 4 are arranged so as to roughly follow the flow of gas in the combustion chamber 5. The ignition device 6 is provided adjacent to the spiral injection valve 4, and the spiral injection valves 4, 4' and the ignition device 6 are included in the support tube γ and are exposed to the combustion chamber 5. ing. The can body 8 is formed of a cylindrical inner shell 9 and an outer shell 9', and the cylindrical combustion chamber 5 is formed inside.

Further, a middle cylinder 11 is provided at the center of the bottom 10 of the combustion chamber 5, and an auxiliary combustion pipe 12 is provided on the outer periphery thereof.

The tips of the spiral injection valves 4, 4' and the ignition device 6 are exposed to the combustion chamber 5 through the wall opening 13 of the combustion chamber 5.
A sufficiently large hole 12A is provided in the auxiliary combustion tube 12 at a position opposite to the auxiliary combustion tube 12 to prevent the atomized fuel particles from colliding with each other. A circulation hole 14 is provided. The spiral injection valves 4° and 4' are provided as an example of a first atomizing means and a second atomizing means, respectively. With such a configuration, there are combustion areas b in the upper part of the combustion chamber 5 and the middle cylinder 11,
The bottom part 10 of the combustion chamber is formed by the middle cylinder 11 and the auxiliary combustion cylinder 12.
A premixing region for forcibly mixing fuel particles and vaporized fuel is formed nearby, and a recirculation flow region C is formed between the combustion chamber 5 and the auxiliary combustion tube 12. Further, a large number of air jet holes 15 are provided around the side wall of the middle cylinder 11 so as to be arranged gradually from the bottom to the top from the tangential direction to the right angle direction, or only in the tangential direction.

Combustion air motor 16, fan 17, fan case 1
The air is supplied to the middle cylinder 12 from the air blowing mechanism composed of the air blowing mechanism 8 . A combustion ring 19 controls the flow of combustion gas in the combustion chamber 5, the amount of recirculation, and the internal pressure.

In the above configuration, when the motor 16 is first energized and the blower mechanism is activated, combustion air is supplied to the middle cylinder 11.
Air is ejected from each air ejection hole 16 on the combustion chamber 5 to the premixing area in the combustion chamber 5 and then to the combustion area a at a constant ratio. At this time, the fuel flow path switching valve 3 connects the first spiral injection valve 4 and the fuel pump 2. After a certain time delay in the operation of the blower mechanism, the ignition device 6 is energized and a spark is generated. As shown in the pump characteristics in FIGS. 3A and 3B, at the same time as a spark is generated, the voltage applied to the fuel pump 2 is gradually adjusted and input for a certain period of time, and as a result, the gradually regulated liquid fuel is transferred to the first fine particles. The fuel is sprayed into the combustion chamber 6 from the spiral injection valve 4 which corresponds to the oxidation means.

When the fuel is in a trench, the fuel flow path switching valve 3 is instantly switched in conjunction with the fuel pressure regulation state to the first spiral injection valve 4, and the flow path is switched to the second spiral injection valve 4'. Switch. At this time, a certain amount of air (less than 215 m of excess air ratio m at steady state) relative to the rated fuel spray amount is ejected from the lower air ejection hole 15 of the middle cylinder 11 into the premixing area. , forming a swirling upward flow in the combustion chamber 5. Therefore, during startup combustion, a fraction of the rated spray amount of fuel is injected roughly along this swirling flow, and the fuel spray amount is gradually increased while performing diffusion mixing, and after the mixture ratio reaches a certain amount. Ignites and burns.

As a result, the amount and area of collision between the fuel particles and the middle cylinder 11 during starting combustion are reduced.

The initial flame in this starting combustion period has an excess air ratio I in the premixing region of approximately 0.9 m (1.5 m), forms a flame with high brightness, and swirls around the middle cylinder 11. As it rises, new combustion air is supplied and diffusion combustion takes place. However, some of the flame remains at the bottom 10 of the combustion chamber 6 and becomes an ignition source for the subsequent fuel. The evaporation and vaporization of the subsequent fuel is further accelerated by the heat of the circulating combustion gas, and combustion occurs while new air is supplied to the fuel line.After this, the concentration of the premixture becomes even higher and combustion occurs. In other words, the bright flame immediately moves to the air nozzle 16 above the middle cylinder 11, takes in air from this nozzle 15, and produces non-bright flame combustion. Multi-stage combustion is performed by forming a large number of single-hole flames while changing.The flow path switching valve 3 switches to the first spiral injection valve 4, and during this time, the fuel injection direction changes by θi, and the fuel injection position changes. However, as the temperature inside the combustion chamber increases, the evaporation and vaporization of fuel particles in the air is rapidly promoted, and the fuel injection direction changes to an angle of θ1, and the position shifts to xil.
However, it does not reach the surface of the inner cylinder 11, and during flight, it completes evaporation and vaporization in the air and mixes with the air. In this way, even if some of the fuel particles are not reliquefied in the initial stage, they are evaporated and vaporized by heat transfer and radiation, forming a stable flame and each air injection hole 15 at the top of the middle cylinder 11, resulting in multi-stage combustion. Perform steady combustion. Therefore, there is no contact area between fuel particles during steady combustion. Unfortunately, due to the change in the direction and position of the fuel injection, it crosses or almost opposes the swirling flow in the combustion chamber 5.

Steam/vaporization of the atomized fuel particles and mixing with air are promoted.

As described above, according to the liquid fuel combustion device of this embodiment, the means for controlling the spray amount during the predetermined starting time, the fuel flight direction θi, and the injection position X are adjusted by switching the flow path switching valve 3. At the initial stage of startup, ■ the mixture ratio of fuel and air can be optimized.

■ Mixing of fuel and air can be promoted.

(2) The collision area and amount of collision between the fine particles of the sprayed fuel and the middle cylinder 11 can be reduced.

1, during the steady combustion period.

■ Mixing can be promoted.

As a result, it is possible to suppress the generation of soot during the transient combustion period from starting combustion, and at the same time, it is possible to suppress the generation of soot particles due to large fuel particles during the steady combustion period. It's a trench, the fuel collision area is reduced and the tar generation area is reduced. Therefore, stable evaporation and vaporization are maintained repeatedly,
Stable vaporized fuel concentration and air-fuel mixture are obtained, resulting in stable combustion. Furthermore, clean combustion and extinguishing are maintained.

Next, another embodiment will be explained using FIGS. 4 and 5. In this embodiment, a valve (relief valve) is inserted between the flow path switching valve 3 and the first spiral injection valve 4 via an orifice 20 as a means for controlling the spray amount during a predetermined period of time during startup. valve) 21 is provided, and the capacity (rated atomization amount) of the first spiral injection valve 4 is set to the second spiral injection valve 4.
The capacity (rated atomization amount) of ' is 215 to 315, and the other essential configurations are the same as those of the above embodiment, and the same numbers indicate the same components. However, after one branch, a return oil vibe 22 is connected to a fuel tank (not shown) via the orifice 20 and the valve 21. Although the operation is exactly the same, the rated spray amount of the first spiral injection valve 4 is set to 215 to 3/3 of the rated spray amount of the second spiral injection valve 4'.
6 and branched midway between the flow rate switching valve 3 and the first spiral injection valve 4 to form the orifice 2o and the valve 21.
By providing this, the spray amount can be controlled without changing the fuel supply pressure, and the fuel injection direction θ
i or the ejection position x1 can be changed, and the same effects as in the above embodiment can be obtained. Note that FIG. 6 shows the pump characteristics in the embodiments shown in FIGS. 3 and 4.

As described above, according to the present invention, the generation of soot and tar can be suppressed, and the combustion characteristics can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the liquid fuel combustion device of the present invention, FIG. 2 is a sectional view taken along line h-A' in FIG. FIG. 4 is a vertical sectional view showing another embodiment of the present invention, and FIG. 5 is A in FIG. 4.
-p: Line sectional view, FIG. 6A. B is a pump characteristic diagram. DESCRIPTION OF SYMBOLS 1...Oil sending pipe, 3...Flow path switching valve, 4...First spiral injection valve (first atomization means), A...First 2-volume injection valve (second atomization means),
5... Combustion chamber, 10... Combustion chamber bottom, 1
1...Middle cylinder, 12...Auxiliary combustion cylinder, 15.
...Air blowout hole, 2o...Orifice,
21... Valve (relief valve), a... Combustion area,
b... Premixing area, C... Recirculation area. Name of agent: Patent attorney Toshio Nakao Haga 1 person No. 5
Diagram 6 diagrams

Claims (4)

[Claims] (1) A cylindrical combustion chamber with a bottom, a middle cylinder with a medium flame erected at the bottom of the combustion chamber and a number of air injection holes on its side wall, and a middle cylinder erected on a concentric circle around the outer periphery of the middle cylinder. a plurality of liquid fuel atomization means in the combustion chamber, a means for controlling the amount of atomization during a predetermined period of time during startup, and a flow path switching of the fuel supply pipe. A liquid fuel combustion device equipped with a valve. (2) The liquid fuel combustion device according to claim 1, wherein at least one of the fuel injection direction and injection position of the plurality of atomization means is made different. (3) First. A second atomization means is provided, and the atomization amount of the fuel of the first atomization means is set to 215 to 215 of the atomization amount of the second atomization means.
315. The liquid fuel combustion device according to claim 1. (4) The liquid fuel combustion device according to claim 1, wherein a valve is connected via an orifice in the middle of the fuel supply pipe between the atomization means and the flow path switching valve as means for controlling the amount of atomization.