JPS641952Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aluminum melting furnace that melts aluminum at high speed and with high thermal efficiency by burning heavy oil or the like.

[Conventional technology]

Aluminum is described in the literature “Light Metals” (Vo1.30, No.
3, 1980), it is known that emisivity is very small, and in particular, molten aluminum becomes a metal mirror and is difficult to absorb heat.

Conventionally, aluminum melting furnaces were reverberatory furnaces that mainly used radiation heat transfer, but in recent years, with the aim of improving the melting rate, so-called convection has been used to promote heat transfer by applying high-temperature combustion gas from the burner directly to the cool material. Heating is attracting attention.

In this case, in order to increase the combustion rate, it is common to swirl the air and increase the jetting rate from the burner tile. However, the life of the tile, _NO
Due to concentration issues, the ejected gas velocity is 60 to 80 m/
sec or less is normal.

An example of attenuation of the gas ejected from the burner tile section in this case is shown in FIG. As shown in FIG. 1, the velocity of the ejected gas decreases rapidly as it leaves the tile section.

In the case of recent large-scale melting furnaces, the distance from the burner to the molten metal surface is 3 m or more, and convection heat transfer effects cannot be expected unless the ejection speed is as high as described above. On the other hand, an example of the temperature pattern and control of the melting furnace and the amount of fuel input at that time is shown in FIG. As is clear from the figure, when switching from furnace temperature control to molten aluminum temperature control during cycle time, the burner firing rate (fuel input rate) becomes a fraction of the starting rate, and the so-called turndown rate of the burner is large. Become something.

When the burner is turned down, the gas speed ejected from the burner decreases approximately in proportion to the turndown rate, causing the combustion flame to become shorter and the flame to rise, resulting in a significant decrease in heating efficiency and uneven furnace temperature. .

This is schematically shown in FIG. (In the figure b
indicates the burner, and F indicates the frame shape. The upper row represents full combustion, and the lower row represents turndown. ) [Purpose of the invention] The present invention is an attempt to solve the above-mentioned problems, and its purpose is to prevent a decrease in heating efficiency and unevenness of the furnace temperature during the latter half of melting and while maintaining the temperature of the molten metal in an aluminum high-speed melting furnace. shall be.

[Structure of the idea]

The above-mentioned object of the present invention is to form a fuel supply passage and its jet hole in the central axis of the burner, while an air supply passage is formed on the outer periphery of the fuel supply passage and has two streams, an inner flow and an outer flow, which are shifted in phase in the radial direction of the burner body. The melting burner is constructed of layers, and the internal air jet holes are formed in the vicinity of the fuel jet holes, and the external air jet holes are formed at a position separated from the internal air jet holes,
This is achieved by an aluminum melting furnace characterized in that the melting burner is arranged so as to point directly at the material to be heated.

Next, the present invention will be explained based on embodiments shown in the drawings.

First, the structure of the melting burner B itself will be explained with reference to FIG. 4. A fuel supply passage 4 and its ejection holes 4' are formed in the axis of the burner body 1. 8 is an inlet for fuel oil, and 9 is an inlet for an atomizing medium for atomizing the fuel.

In the present invention, the combustion air supply path includes an inner flow pipe 3 and an outer flow pipe 2 on the outer periphery of the fuel supply path 4.
It is made up of two layers that are out of phase. At this time, the ejection hole 3' of the inner flow pipe 3 is located near the fuel ejection hole 4', and the ejection hole 2' of the outer flow pipe 2 is located at a position further away from the above-mentioned inner flow pipe ejection hole 3'. is formed. Note that 5 is a viewing window, 6 is an ignition hole, and 7 is a damper for external air.

Next, in the present invention, as shown in FIG. 5, the melting burner B having the above-described structure is attached to the side wall of the circular furnace body 10 facing the charge material (material to be melted) 11. Note that 12 indicates a molten metal, 13 an exhaust flue, 14 a door, and 15 a ceiling cover.

[Functions and effects of the invention]

The operation of the melting furnace of the present invention will now be described. First, the material to be melted is charged by removing the ceiling cover 15 and using a crane or the like to load the material in a bucket or other means.

After charging the materials, the cover 15 is attached again and the burner B is ignited to start the melting operation. The flame of the ignited burner B is the charging material 11
Then, preheating begins and melting begins. From the start of melting to the latter half of melting, the burner combustion amount reaches a maximum value or a value close to it, and the flame hits the charged material 11, resulting in high-speed melting due to the synergistic effect of convection heat transfer and flame radiation.

However, in the latter half of melting, complete melting, and further in the molten metal temperature control range, the burner combustion amount turns down, and the burner flame becomes shorter than during maximum combustion. On the other hand, the charge material 11 also melts, falls down, and becomes smaller, making it difficult for the burner frame to reach the charge material. At that time, air damper 7
, cut off the outside air and use only the internal air to form a flame that moves in a straight line, as if it were the maximum combustion of a small-capacity burner (see Figure 6, a) to b )fart). By doing so, it is possible to improve the problems of conventional burners, such as the decrease in heating efficiency during turndown and the non-uniformity of the furnace temperature.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the attenuation state of ejected gas in the atmosphere, Figure 2 is a diagram showing the relationship between melting furnace temperature control and fuel input rate, and Figure 3 is a diagram showing the relationship between melting furnace temperature control and fuel input rate. Explanatory diagram of frame shape, 4th
The figure is an explanatory diagram showing the burner structure according to the present invention,
Figure 5 is an explanatory diagram of the melting furnace of the present invention, where a is a plan view;
b is a side view, and FIG. 6 is an explanatory view of the frame shape of the burner according to the present invention at the time of maximum use a and at the time of turndown b. 1: burner body, 2: outer flow pipe, 3: inner flow pipe,
4: Fuel supply path, 5: Peephole, 6: Ignition hole, 7:
Air damper, 8: Fuel oil inlet, 9: Spray medium inlet, 10: Circular furnace body, 11: Charge material, 12: Molten metal, 13: Exhaust flue, 14: Door, 1
5: Ceiling cover.

Claims (1)

[Scope of utility model registration request] A fuel supply passage and its jet holes are formed on the central axis of the burner, while the air supply passage consists of two layers, an inner flow and an outer flow, which are located on the outer periphery of the fuel supply passage and whose phases are shifted in the radial direction of the burner body. A melting burner is formed by forming a blowing hole for the flowing air near the fuel blowing hole and a blowing hole for the external air at a position separated from the blowing hole for the internal air. An aluminum melting furnace characterized by being arranged so as to be oriented.