JPS6243088B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid fuel combustion device that gasifies liquid fuel such as kerosene and burns it with blue flame without using a preheater.

FIG. 1 shows the operating principle that is the premise of the present invention. A rectifier plate 3 having an opening 2 is provided in a cylinder 1 through which forced airflow flows, and a gap between the rectifier plate 3 and an air gap is provided on the leeward side of the opening of the rectifier plate 3. 4 is removed and a rectifying cylinder 5 is provided.

In this way, part of the airflow that has passed through the opening 2 becomes a negative pressure in the gap 4 due to the high-speed airflow.
Recirculation occurs as indicated by the arrows shown.

Conventionally, the one shown in FIG. 2 is known as a liquid fuel combustion device applying this principle. In the one shown in Fig. 2, a furnace tube 7 is provided coaxially with the blast tube 6, a nozzle 10 and a spark plug 11 are arranged on the windward side of a rectifying plate 9 having an opening 8, and a rectifying plate 9 and a gap 12 are arranged on the leeward side. A rectifying cylinder 13 is arranged in a leaning position.

Such a combustion device uses the principle shown in Figure 1 to reverse transport the combustion gas, thereby heating and vaporizing oil droplets (70 to 100 μm) as fuel sprayed from the nozzle 10 into fine particles (1 to 5 μm). (gasification) and burns with blue flame. However, the combustion flame 14 becomes a concentrated flame with a large flame density, and part of the flame is included in the strong reverse transport flow, resulting in pulsating combustion, and the combustion is accompanied by loud low-frequency noise. At the same time, there was a drawback that ignition occurred before sufficient gasification occurred, resulting in yellow flame, and complete blue flame combustion could not be expected.

The present invention is aimed at solving the problems of the prior art described above, and in a device that reversely transports (recirculates) the combustion gas to gasify the liquid and burn it with blue flame, the combustion flame is concentrated. The purpose of the present invention is to create a laminar flow without causing any turbulence, eliminate pulsating combustion by preventing flames from being included in the reverse transport flow, and achieve stable blue flame combustion with low low frequency noise.

The basic structure for achieving this purpose is as described in the claims, and uses a small eddy current generated on the surface of the flame stabilizing tube while dispersing the combustion air flow with a baffle plate. The laminar flame is stabilized on the surface of the flame-holding cylinder, and the combustion gas that is transported back by the straightening cylinder is detoured along the combustion furnace wall using a guide plate, so that the combustion flame is directly reversed. This prevents pulsating combustion from being transported and prevents ignition before the mixture of fuel and combustion air is sufficiently gasified.

Therefore, according to the present invention, the combustion flame becomes a laminar flow flame, stable blue flame combustion without pulsation is performed, low frequency noise can be significantly reduced, thermal efficiency is improved, fuel consumption is saved, and soot is reduced. Maintenance management can also be simplified because the occurrence of problems is reduced.

An embodiment of the present invention shown in the drawings will be described below.

Figure 3 shows the liquid fuel combustion device of the present invention in water heater 1.
5, the combustion furnace 16 is the inner cylinder 17
The outer periphery of the combustion furnace 16 is surrounded by an outer can 20 to form a water chamber 21. A chimney 22 for discharging combustion exhaust gas to the outside is connected to the top plate 19, and a rectifying plate 24 for rectifying the combustion air from the blower 23 is provided at the outlet of the bottom plate 18, and the combustion air is sent to the combustion furnace. An air supply pipe 25 discharging into the air supply pipe 16 is connected to the air supply pipe 25 . 26 is a rectifier plate 24 along with a spark plug 27
This is a fuel spraying nozzle introduced into the combustion furnace 16 through the nozzle, and a fuel supply pipe 29 into which a pressure pump 28 is inserted is connected. Reference numeral 30 indicates a combustion furnace 16 by removing a gap 31 from the bottom plate 18 forming the combustion furnace wall.
It is a straightening tube installed inside the nozzle 26 and oriented in the fuel spray direction of the nozzle 26, and has the function of transporting a part of the combustion gas back so as to mix it with the mixture of fuel and combustion air. Reference numeral 32 denotes a flange-shaped guide plate attached around the lower opening of the rectifier cylinder 30, which detours the reverse transport flow of combustion gas along the bottom plate 18 to prevent the combustion flame from being directly reverse transport. It is also used to adjust the combustion gas to a temperature suitable for fuel gasification.
Reference numeral 33 denotes a flame-holding cylinder made of wire mesh placed on the guide plate 32 so as to surround the sides and upper part of the straightening cylinder 30, and the combustion gas flow passing through the surface 34 generates a small vortex flow and prevents combustion. The mesh size (8 meshes in this example) is used to the extent that it does not impede the reverse gas transport flow.

Focusing on the fact that the flow velocity and distribution of combustion air can be changed by changing the diameter and arrangement of the small holes, the current plate 24 has a large number of small holes so as to obtain an appropriate flow velocity and a dispersed combustion air flow. , whose diameter and arrangement are determined, and the mixture of fuel and combustion air flows into the flame-holding tube 3.
It is made to spread toward the upper part of the surface of 3 in an inverted conical shape. The flame-holding cylinder 33 is not limited to one made of wire mesh, and may be formed using a porous plate, but it is convenient to use a commercially available and inexpensive one made of wire mesh. be.

Next, the operation of the above embodiment will be explained with reference to FIGS. 3 and 4. First, after pre-purging is performed by operating the blower 23, the pressurizing pump 28 is operated and the spark plug 27 is energized (for several seconds).
The mixture of combustion air discharged from the air supply pipe 25 passes through the rectifying tube 30, spreads into the flame stabilizing tube 33 in an inverted conical shape, and is instantaneously ignited. As shown in Figure 4, the combustion flame is formed at a position where the flow velocity of the mixture of fuel and combustion air, indicated by arrow A, and the flame propagation velocity (also referred to as combustion velocity), indicated by arrow B, are balanced. Since the oxygen concentration in the combustion furnace 16 is the same as that in the atmosphere, the combustion flame immediately after ignition is formed inside the flame stabilizing tube 33 and becomes a laminar yellow flame. Then, 2 to 3 seconds after ignition, a part of the combustion gas consisting of components such as CO ₂ , N ₂ , H ₂ O, etc. is transported back (see arrow C) due to the action of the rectifying tube 30 , and The mixture of fuel and combustion air is mixed within the combustion chamber. For this reason, the oxygen concentration within the flame stabilizing tube 33 decreases, and the combustion speed decreases, so that the combustion flame that was formed inside the flame stabilizing tube 33 immediately after ignition tries to move to the outside of the flame stabilizing tube 33. However,
Since the flame-holding tube 33 is made of wire mesh, a vortex 35 is generated on its surface 34, and the flame is held on the surface 34 (mainly at the top) of the flame-holding tube 33, as shown in FIG. At the same time, sprayed from nozzle 26
The fuel consisting of oil droplets of 70 to 100 μm receives the heat of the combustion gas that is transported back and becomes gasified fine particles of 1 to 5 μm, and the combustion flame changes to a blue flame.

Since the vortex 35 generated on the surface of the flame stabilizing cylinder 33 is small due to the mesh, the combustion flame is held at its base. Since the mixture of vaporized fuel and combustion air is widely distributed in the flame stabilizing tube 33, the flame as a whole becomes a laminar flame that flows upward from the surface 34 of the flame stabilizing tube 33, causing the combustion to occur like a concentrated flame. There is no gurgling sound.

Further, since a flange-shaped guide plate 32 is provided around the lower opening of the rectifying tube 30, the rectifying tube 3
The reverse transport flow of combustion gas due to the
0, the temperature is adjusted to a temperature suitable for vaporizing the fuel sprayed from the nozzle 26 (200 to 500°C), and the temperature does not reach the temperature (500°C or higher) that ignites the fuel before vaporizing. You can do it like this. Therefore, the combustion flame stabilized on the surface of the flame stabilizing tube 33 returns to the rectifying tube 30 and the flame stabilizing tube 33 again, and pulsating combustion can be prevented, resulting in stable blue flame combustion without yellow flame. You will be able to do it.

As described above, according to this embodiment, the flame-holding cylinder 33
Since a laminar flame can be formed on the surface 34 and pulsating combustion can be prevented by the action of the guide plate 32, low-frequency noise can be significantly reduced and stable blue flame combustion can be realized by gasification. Therefore, thermal efficiency is improved, fuel consumption can be saved, soot generation is reduced, maintenance and inspection can be simplified, and other excellent effects are achieved.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the operating principle that is the premise of the present invention, Fig. 2 is a cross-sectional view of a conventional device applying the principle of Fig. 1, and Fig. 3 is an example in which the device of the present invention is applied to a water heater. FIG. 4 is a sectional view of a main part for explaining the combustion state of the device shown in FIG. 3 immediately after ignition. 16... Combustion furnace, 24... Straightening plate, 25... Air supply pipe, 26... Nozzle, 30... Straightening cylinder, 3
2... Guide plate, 33... Flame-holding tube.

Claims (1)

[Scope of Claims] 1. A fuel atomization nozzle introduced into a combustion furnace, an air supply pipe that discharges combustion air into the combustion furnace from the outside of the nozzle, and an outlet portion of the air supply pipe. a baffle plate provided with a large number of small holes for distributing the combustion air flow; and a counter-transport plate provided in the fuel spray direction of the nozzle to mix the combustion gas with the mixture of fuel and combustion air. a porous flame-holding tube that surrounds the sides and upper part of the flow-straightening tube so as to hold the flame on its surface;
A liquid fuel combustion device characterized by comprising a guide plate that detours the combustion gas reverse transport flow of the straightening tube along a combustion furnace wall. 2. The liquid fuel combustion device according to claim 1, wherein the flame-holding tube is made of wire mesh.