JPS594632B2 - aluminum melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum melting furnace that can prevent the formation of aluminum oxide in an oxygen-free state and has significantly improved thermal efficiency.

Conventional aluminum melting furnaces inject and burn heavy oil into the furnace using a combustion device, and use the radiant heat to melt the aluminum base metal.Then, as the molten aluminum is taken out from the sprue, the aluminum base metal is intermittently supplied into the furnace. It has a structure in which gold is melted by radiant heat from the combustion of heavy oil and heat transfer from molten aluminum, and since the combustion flame comes into direct contact with molten aluminum, aluminum oxide of approximately 2.5% is produced. Therefore, for example, in a furnace with a monthly production capacity of 1,000 tons, 25 tons of aluminum oxide are produced, which must be disposed of, resulting in a huge loss of costs.

On the other hand, recently developed aluminum melting furnaces include electric furnaces that have heat transfer wires installed in the furnace and use the radiant heat of the heat transfer wires and the heat transfer of molten aluminum to melt the aluminum base metal. After the gold has been oxidized by the amount of oxygen in the initial air in the furnace, it is possible to melt one piece of aluminum in an oxygen-free state, so the amount of aluminum oxide produced is extremely small and can be suppressed to about 0.3%. Although it is attracting attention in the industry, it has the disadvantage of extremely high power consumption.
There are some difficulties in installing the equipment in terms of running costs.

Further, since conventional aluminum melting furnaces are generally not configured to use exhaust gas for preheating, the thermal efficiency is only about 20 factors.

Even in furnaces for other uses, if exhaust gas is used for preheating, the thermal efficiency can be increased to about 40 coefficients and fuel consumption can be halved.

Therefore, there is a strong demand for a preheating structure in aluminum melting furnaces as well.

In the present invention, a heat dissipation tube is provided in the furnace, and the aluminum ingot supplied to the furnace is melted in an oxygen-free state by combustion within the tube, and the amount of aluminum oxide produced is approximately 2.5 that of the conventional furnace.
The purpose of the present invention is to provide an aluminum melting furnace that is of a gas combustion type that can significantly reduce the heat dissipation rate to approach that of an electric furnace at 0.3, and has a high thermal efficiency using an aluminum feed tube as a preheating chamber.

Embodiments of the aluminum melting furnace of the present invention will be described below with reference to the drawings.

A furnace body 3 is formed by lining a casing 1 with heat-resistant fibers or ceramic fibers 2.

In this furnace body 3, the hearth 4 is set high on the aluminum supply cylinder 5 side at the rear of the furnace and low on the sprue 6 side at the front of the furnace, and also blocks radiant heat in the furnace 7 from escaping to the aluminum supply cylinder 5'. A descending wall 8 is provided, and the rear wall of the furnace body 3 and the hearth 4 are connected by a smooth curved surface with a large radius of curvature, and the sprue 6 is provided with a hot water tap 9.

In order to melt the aluminum ingot dropped into the hearth 4 from the aluminum supply tube 5 in an oxygen-free state, the combustion device 10 injects gas into the tube and uses the radiant heat of the combustion to melt the aluminum ingot fed into the furnace. A heat dissipation pipe 11 is provided which can be melted and through which exhaust gas is guided to the aluminum feed tube 5.

The heat dissipation tube 11 is made of a high-humidity and heat-resistant material that can withstand temperatures of about 1000°C, and is made of a straight tube as shown in the figure or a curved tube in a U-shape or meandering shape, and may be one or two depending on the required heat capacity. The above are provided.

The combustion device 10 is attached to one end of each heat radiation pipe 11 outside the furnace, and is connected to the cylinder 13 through a gas pipe 12A and a main plug 12B.
It is connected to a gas supply source such as a gas tank or a tank room.

The other end of each heat radiation tube 11 also protrudes outside the furnace, and this end is connected to the exhaust gas header 14, and the end of this exhaust gas header 14 is connected to the aluminum supply tube 5. The exhaust gas from the pipe 11 is guided to the aluminum supply cylinder 5.

The exhaust gas header 14 is not an essential component of the present invention.

For example, if the heat dissipation pipes 11 are arranged in different directions so that the combustion device 10 is on the same side as the illustrated sprue 6, and a hole is provided in the descending wall 8 of the furnace body 3, a modified configuration is adopted. The exhaust gas header 14 is not necessary because the exhaust gas from each heat dissipation tube 11 can be directly guided to the aluminum supply cylinder 5 through this hole.

Insulating material 1 is installed on the exhaust gas header 14 etc. outside the furnace to prevent heat radiation.
5 is coated.

The combustion device 10 has a heat dissipation tube 11 made of aluminum with a melting point of 6
It has a capacity that can adjustably heat the temperature in the range of 700°C to 1000°C, which is higher than 60°C.

In this way, the heat dissipation tube 11 is provided in the furnace 7, and when gas is injected and burned within this tube, the furnace interior 7 becomes anoxic.

This is because the oxygen content in the air that initially exists in the furnace 7 is soon exhausted by the formation of aluminum oxide, and the oxygen content in the exhaust gas from the aluminum supply tube 5 is reduced because the furnace interior 7 is on the high pressure side. This is because it is difficult to diffuse into.

An exhaust gas header 14 is used to guide the exhaust gas from the heat dissipation pipe 11 to the aluminum supply tube 5 and use the aluminum supply tube 5 as a preheating chamber.
Since the exhaust gas from the exhaust gas is much higher than the melting point of aluminum, 660°C, and cannot be used for preheating as it is, an exhaust gas cooling device 16 is provided that can cool the exhaust gas to about 550°C.

This device 16 may have any configuration as long as it does not adversely affect the aluminum base metal and molten aluminum, but it is convenient to use a blower that blows cold air as shown in the figure.

The blower 16 may be installed at any position as long as the cold air can be sufficiently mixed with the exhaust gas. For example, the blower 16 may be blown into the aluminum supply cylinder 5, but as shown in the figure, the blower 16 may be installed at a bend portion of the exhaust gas header 14. Sufficient mixing of the cold air and the exhaust gas is achieved by blowing air from the provided cold air outlet 16A while ensuring prevention of noise generation.

A shelf device 18 capable of stocking metal in order to use the aluminum supply cylinder 5 as a preheating chamber and dropping the metal into the hearth 4 when desired.
is provided.

This shelf device 18 is provided above the exhaust gas population 11 in the aluminum supply cylinder 5, and includes, for example, an opening/closing bar 21 in which a shelf board 20 is attached to the shaft 19 and the shelf board 20 is fixed to the end of the shaft 19 outside the furnace. By releasing the lock of the stopper 22 and turning it half way, it is possible to open the base metal AA from the solid line position where it is placed as shown by the arrow 23 and drop the base metal into it.

In addition, this shelf device 18 distributes the exhaust gas in a lattice, net, or porous shape on the shelf 20 in order to sufficiently circulate the exhaust gas at about 550°C around the metal placed on the shelf 20. It is formed into a shape that can be used.

If the ventilation resistance caused by the shelf board 20 is too large, it will be extremely difficult for the exhaust gas to rise inside the cylinder, resulting in abnormally high pressure inside the furnace and incomplete gas combustion. It is preferable to use a lattice shape or the like with as many gaps as possible so that it can be placed thereon.

From the point of view of increasing thermal efficiency, there is no problem with the shelf device 18 having one stage, but in order to make the use of the exhaust gas for preheating in the aluminum supply pipe 5 more efficient, the above-mentioned shelf device 18 is designed as shown in the figure, taking into account ventilation resistance. Provide as many tiers as possible.

It is also assumed that a packet conveyor is installed to supply the required amount of metal to the top shelf device 18.

Next, the operation of the aluminum melting furnace configured as described above will be explained.

First, a predetermined amount of aluminum ingots and other aluminum scraps (hereinafter referred to as aluminum ingots) are placed in the furnace 7.

). This supply is performed by supplying the metal to the uppermost shelf device 18 using a packet conveyor (not shown) and dropping the metal into the lower shelf devices one after another.

When the initial supply of metal into the furnace 7 is completed, metal is also stocked in the shelf devices 18 of each stage.

Next, or prior to this, gas is injected and burned within the heat dissipation tube 11 by the combustion device ``0''.

Then, inside the furnace 7, the temperature of the heat dissipation tube 11 changes from 700°C to 1000°C.
The metal is heated in a controlled manner within a range of approximately ℃, and the metal is melted by the heat radiation.

Initially, the furnace interior 7 contains oxygen in the air and produces aluminum oxide, but after the oxygen content is oxidized, the furnace interior 7 becomes the high pressure side, so the oxygen content in the exhaust gas, that is, CO and C
It is extremely difficult for O2 to diffuse into the furnace interior 7, so that the furnace interior 7 becomes anoxic and the production of aluminum oxide is significantly reduced by 2.5 times the amount of conventional furnaces.

It has been demonstrated in an electric furnace that heats with radiant heat from heat transfer wires that the coefficient can be suppressed to about 0.3 in an oxygen-free state.

Exhaust gas from the heat dissipation pipe 11 is led to the aluminum supply pipe 5 via the exhaust gas header 14. The metal stocked in the multi-stage shelf device 18 is preheated, and the thermal efficiency is increased to nearly twice that of the case without preheating. It is discharged at a lower temperature.

The oxygen content in the exhaust gas is CO2CO2, and the exhaust gas temperature is about 50°C, so the metal stocked in the aluminum supply tube 5 is not very active in producing aluminum oxide, so preheating is necessary. conduct.

In this way, the metal that is initially supplied into the furnace 7 is melted in an oxygen-free state by the radiant heat of the heat radiation tube 11.

The radiant heat of the heat dissipation pipe 11 is prevented from escaping into the aluminum supply cylinder 5 by the descending wall 8 and contributes to melting of the metal.

When it is detected through a viewing window (not shown) that the entire amount of aluminum in the furnace 7 is in a molten state, the hot water tap 9 is removed and the required amount of molten aluminum is taken out from the sprue 6 using a ladle or the like.

After wrapping: Lowermost shelf device 18 with preheated stock
of bullion is dropped into the hearth 4, and when the lowest shelf device 18 is restored, the bullion stocked on the shelf device above it is dropped, and in this way, the bullion stocked on the upper shelf is transferred to the lower shelf one after another. fall into it.

The ingot dropped into the hearth 4 is melted by the radiant heat of the heat radiation pipe 11 and the heat transfer of the molten aluminum, but the ingot falls into the hearth 4.
Since it is preheated to about 50°C, it is quickly raised to the melting point of 660°C and melted, and the melting ability is increased by the preheating efficiency.

As described above, aluminum is continuously melted.

As explained above, the aluminum melting furnace of the present invention has
In order to melt the aluminum ingot in an oxygen-free state, a heat dissipation tube is installed in the furnace as a combustion chamber where the flame and molten aluminum do not come into contact. Because the structure is equipped with a device and a shelf device, the metal supplied to the furnace can be continuously melted in an oxygen-free state using the radiant heat from the heat sink and the heat transfer from the molten aluminum, and unlike conventional methods, the heavy oil flame directly melts the aluminum Amount of aluminum oxide produced in an aluminum melting furnace in contact with
．． 5 ratio can be significantly reduced, a large amount of loss can be avoided, and the thermal efficiency can be increased to nearly double that without preheating, fuel costs can be cut by nearly half, and the furnace can be made much smaller than conventional furnaces.

[Brief explanation of the drawing]

The drawings relate to an embodiment of the aluminum melting furnace of the present invention, and FIG. 1 is a vertical side view, FIG. 2 is a cross-sectional view taken along ■-■ in FIG. 1, and FIG. 3 is a cross-sectional view taken along ■-■ in FIG. be. 4...Aluminum supply cylinder, 7...Furnace interior, 1
0... Combustion device, 11... Heat radiation pipe, 1
6...Exhaust gas cooling device, 18...Shelf device.

Claims (1)

[Claims] 1. Gas is injected into the pipe by the combustion device and the radiant heat of combustion can melt the aluminum ingot supplied into the furnace, and one or more heat dissipation pipes are provided to guide the exhaust gas to the aluminum supply pipe, and the aluminum supply pipe is An exhaust gas cooling device capable of cooling the exhaust gas introduced into the cylinder to a temperature lower than the melting point of aluminum is provided, and a shelf device is provided through which the cooled exhaust gas can flow and on which aluminum ingots can be placed and dropped. An aluminum melting furnace featuring: