JPS5849810A - Combustion apparatus for liquid fuel - Google Patents

Abstract

PURPOSE:To completely burn liquid fuel in a combustor, and to enable to change the rate of combustion over a wide range, by burning a part of liquid fuel sprayed into a vaporizing chamber, and by vaporizing the sprayed liquid fuel by heat produced by burning fuel. CONSTITUTION:A nozzle 2, opened to the other end of a vaporizing chamber 3, and a diffusion plate 9, faced to the nozzle 2, are provided to one end of a vaporizing chamber 3, of which one end is closed, while the other end is opened. The primary air feed holes 7 are provided in the neighborhood of a nozzle 2 in the vaporizing chamber 3, on the other hand, the secondary air feed holes 12 are provided to the downstream side against the other open end of a vaporizing chamber 3. With such an arrangement, a liquid fuel combustor with low noise, in which soot, carbon monoxide, and the like, are scarcely produced, complete combustion can be taken place with blue flames from the time immediately after ignition, in addition, the rate of combustion can be changed over a wide range, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid fuel combustion device that sprays liquid fuel through a nozzle, vaporizes the sprayed liquid fuel in advance, and then performs combustion.

As a method for burning liquid fuel, a spray combustion method is widely used in which liquid fuel is atomized and burned in order to improve mixing with air and promote vaporization.

However, it is difficult to quickly mix air with atomized liquid fuel, which has an extremely large momentum compared to gaseous fuel, and is usually forced to mix with air that is swirled or disturbed. Therefore, considerable noise is generated due to the turbulence of this air flow and the difference in evaporation rate of the sprayed liquid fuel, and if it is not properly mixed with air, it generates soot and carbon monoxide. There are drawbacks that can easily occur. In order to overcome this drawback, liquid fuel may be vaporized, mixed with air, and then premixed and combusted, and this method has been known as the gunpot method. In this method, sprayed liquid fuel is vaporized by colliding with a solid wall that is heated by combustion heat, and the heating source for the solid wall is a pore flame held by a large number of small air supply holes.

However, this method has the drawback that the temperature of the solid wall does not rise sufficiently immediately after ignition, so complete combustion cannot be achieved, and soot and odor are generated within the start-up time.

Furthermore, when the combustion amount is varied, it is difficult to hold the pore flame in a small combustion amount region, so there is also a drawback that the range of change in the combustion amount cannot be widened.

The present invention has been made in order to improve such drawbacks, by burning a part of the sprayed/atomized liquid fuel in the vaporization chamber, and using the resulting heat to vaporize the sprayed liquid fuel. Premix combustion is achieved by supplying secondary air in multiple stages to the flow, and complete combustion with blue flame can be achieved in a short period of time after ignition, making it possible to provide a low-noise liquid fuel combustion device in which the combustion amount can be varied over a wide range. It is something.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. In the figure, liquid fuel is pressurized by a pump 1, supplied to a nozzle 2, and sprayed into a cylindrical vaporization chamber 3. The nozzle 2 is a return type variable spray amount nozzle, and by adjusting the return flow rate flowing into the return pipe 4, the amount of spray can be changed and the combustion amount can be varied. Combustion air is supplied by a blower fan 6 via an air amount regulator 6. - Secondary air is ejected from a plurality of primary air supply holes 7 provided at the bottom of the vaporization chamber 3 and is supplied into the vaporization chamber 3. -Next air is nozzle 2
This is supplied to perform primary combustion, which serves as a heat source to vaporize the liquid fuel sprayed from the fuel tank.In the secondary combustion, only the amount of heat required to vaporize the liquid fuel sprayed from the fuel tank is generated, and the loss due to heat radiation is Even if this is included, the amount of air in the fire may be about 101 of the total amount of combustion air. At the time of ignition, the nozzle 2 sprays at the minimum amount, and the ignition electrode 8 ignites. Immediately after ignition, diffusion combustion occurs in the primary air, and a diffusion flame is formed at the bottom of a disc-shaped diffusion plate 9 formed of punched metal held in a position facing the nozzle 2 in the vaporization chamber 3. Within a short time after ignition, the diffuser plate 9 becomes red hot, and the adhering unburned liquid fuel droplets begin to vaporize, and when the vaporization chamber 3 is filled with high-temperature fuel vapor, a pore flame is formed in the secondary air supply hole 7. be done. Once the pore flame is stabilized, all of the secondary air is consumed by the pore flame, so that the diffusion flame burning in the center of the vaporization chamber 3 is extinguished. After that, the combustion exhaust gas generated by the pore flame becomes the heat source for vaporization, and the combustion exhaust gas is transferred to nozzle 2.
At the base of the spray, it is drawn into the spray by the attraction effect and rises while mixing with the spray, heats the diffuser plate 9, passes through the small holes of the diffuser plate 9, and generates turbulence, thereby promoting mixing. On the other hand, because the opening 10 at the other end of the vaporization chamber a is narrowed and the static pressure at the lower part of the vaporization chamber 3 decreases due to the attraction effect at the base of the spray, the area near the wall of the vaporization chamber 3 is lowered from the upper part. A circulating flow is generated which is directed to the bottom, sucked into the spray at the bottom, and directed back to the top. Most of the vaporization of the liquid fuel occurs when the spray collides with the heated diffusion plate 9, but the spray that is not collected by the diffusion plate 9 is mixed with the combustion exhaust gas and circulated within the vaporization chamber 3 by the above-mentioned circulation flow. As the vaporization progresses, the vaporization chamber 3 is eventually filled with a homogeneous mixture of vaporized fuel vapor and combustion exhaust gas.1. After that, fuel vapor can be obtained according to the amount of spray.

A disk-shaped deflector 11 is provided above the opening 10 of the vaporization chamber 3, and the fuel vapor flowing out from the opening 10 is regulated in its flow direction and ejected. Since the flame port plate 13 is provided with a plurality of secondary air supply holes 12 in multiple stages approximately parallel to this flow direction, secondary air is supplied approximately perpendicular to the ejected fuel vapor and combustion occurs. Since the fuel and air are premixed by colliding violently within the extinguishing distance on the flame port plate 13, the secondary flame formed is a blue premixed flame. Further, a flame control plate 14 is provided protruding from the outside of the flame port plate 13 to prevent unburned fuel vapor from being discharged. In this way, in secondary combustion, combustion is performed by premixing, so in addition to low noise, the flame length is short and it is possible to take a large combustion load per unit volume, and the combustion chamber facing the secondary air supply hole 12 The volume can be reduced.

In addition, it is possible to improve the disadvantage that, as in conventional liquid fuel combustion devices, liquid fuel in the form of droplets is present in the flame, which increases the local equivalence ratio and makes it easier to generate soot and carbon monoxide. It is possible to completely burn it easily. In addition, when configured as in this embodiment, only the diffusion plate 9 needs to be heated in order to vaporize the liquid fuel, so the rise after ignition is extremely short compared to conventional pot-type combustion devices. We sometimes perform ignition start-up with the minimum amount of spray,
No odor or soot is generated immediately after ignition.

Therefore, plate-fin type heat exchangers, etc., which could not be used in the past due to blockage, are fully applicable.

Furthermore, when the combustion amount is varied in the conventional pot-type combustion device, it is difficult to reliably hold the pore flame in the small combustion amount region, and the flame is easily extinguished. This reduces the size of the pore flame that forms in the air supply source to prevent the fuel from becoming too hot and causing red flames and soot, thereby suppressing the amount of heat generated. Therefore, if the combustion amount is reduced, the stomatal flame approaches the wall, increasing heat loss from the flame to the wall and extinguishing the flame. However, unlike the conventional pot-type combustion apparatus, in this embodiment, the amount of phosphorus vaporized is not changed too much to prevent the primary flame from extinguishing, and the amount of combustion is changed by secondary combustion. This is done by changing the number after the second order, rather than changing the size of everything after the second order. In other words, when the amount of spray is reduced, the amount of fuel vapor ejected from the vaporization chamber 3 is reduced, and the fuel vapor is combusted by the air supplied from the inner secondary air supply hole 12. The liquid fuel does not reach this point and gradually goes out through the secondary air supply holes 12 on the outside, and the number of secondary air sources decreases. Therefore, the size itself after secondary does not become so small that flame holding becomes difficult, and as is clear from the above explanation, the present invention can burn soot, carbon monoxide, etc. over a wide range. It is possible to provide a liquid fuel combustion device that generates extremely little amount, allows ignition to be varied over a wide range, and has low noise.

[Brief explanation of drawings]

The figure is a sectional view of a liquid fuel combustion device according to an embodiment of the present invention. 2...Nozzle, 3...e@e, vaporization chamber, 6...-
...Blower fan, 7.--Next air supply hole,
9・φ... Diffuser, 10... Opening, 11
...Deflection body, 12..Secondary air supply hole, 13.Fist...flame mouth plate.

Claims (1)

[Claims] A vaporization chamber with one end closed and the other end open, a nozzle opened toward the other end of the vaporization chamber in the vaporization chamber, and a diffuser plate provided opposite the nozzle in the vaporization chamber. A liquid fuel combustion device comprising: a primary air supply hole provided in the vicinity of the nozzle of the upper string vaporization chamber, and a secondary air supply hole provided downstream of the opening at the other end of the vaporization chamber.