JPS6129037Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a small melting furnace for non-ferrous metal materials (aluminum, aluminum alloy, copper, etc.), and in particular to a crucible for the purpose of improving thermal efficiency. This relates to mold melting furnaces.

[Prior art]

Conventionally, crucible-type melting furnaces have been widely used as small melting furnaces for melting non-ferrous metal materials, but their thermal efficiency has been extremely low. That is, as shown in FIG. 2, the conventional crucible-type melting furnace 10 has a crucible 12 surrounded by a furnace wall 11 made of a heat insulating material, fixed by a support member 13, and disposed at a lower burner port 11a. Opening 1 is heated by a combustion burner (not shown).
The non-ferrous metal materials introduced from 4 were being melted.
Since most of the heat escaped from the exhaust pipe 15 as exhaust gas, the thermal efficiency was extremely low.

However, since the first oil shock in 1971, fuel costs have increased, and energy-saving reactors have been required even for small reactors, and various studies have been conducted.

As such, there is a melting furnace that has a metal heat exchanger installed in the exhaust gas passage and an air preheating chamber for preheating the combustion air of the furnace.If the combustion air is preheated with the exhaust gas, It has been confirmed through experiments that fuel efficiency is improved to some extent.

However, in crucible-type melting furnaces that use non-ferrous metal materials as raw materials, solvents are used to separate oxides from the melted non-ferrous metal materials, and these solvents generate chlorine-based or fluorine-based corrosive gases. Therefore, when the heat exchanger is provided in the exhaust gas passage, there is a problem that the heat exchanger is corroded and has a short lifespan.

Furthermore, there was also the problem that improvement in thermal efficiency to a certain extent (usually within 10%) was unsatisfactory.

Therefore, in order to improve thermal efficiency, it is considered most appropriate to preheat the molten material (referring to unmelted non-ferrous metal material) by bringing it into direct contact with the exhaust gas, as is used in large furnaces. Therefore, the preheating device employed in this large furnace will be explained below.

As shown in FIG. 3, a conventional melting furnace 16 with a preheating device includes a melting furnace main body 17 (in the figure, it is in the form of a reverberating furnace) and a preheating tower 18. The preheating tower 18 has multiple shelves (trays) 1
9 is built in, and a shelf 19 is adapted to load a melting material 20. This shelf 19 has a mechanism that can be opened and closed freely, and by opening and closing, it is possible to drop and move the raw material molten material 20 to the lower shelf.

A burner 21 (also located at a position not shown) is provided at the bottom of the preheating tower 18 to melt the melting material 20 and keep it warm.

With this configuration, the melting material 20 introduced from the input port 23 is gradually preheated in the preheating tower 18,
It is put into the melting furnace main body 17 and melted.

Therefore, although a certain degree of improvement in thermal efficiency can be expected, due to the uneven flow caused by the blow-through of the exhaust gas in the preheating tower 18, the melting material cannot be uniformly preheated. was difficult.

Furthermore, since the preheating tower is composed of multiple stages, when applied to the crucible-type melting furnace, which is a small furnace as described above, the preheating device becomes large, and as a result, heat is also taken up by the preheating device, resulting in a decrease in thermal efficiency. There was a problem that not only was there no significant improvement, but the crucible-type melting furnace as a whole became large and could not be applied in reality. Therefore, there has never been an example of a small crucible type melting furnace in which a preheating tower as used in the above-mentioned large furnace is activated.

The present invention was developed in view of the above circumstances, and it not only dramatically increases the thermal efficiency of small furnaces, which was previously difficult, but also provides a crucible-type melting furnace that can melt non-ferrous metal materials with a small size, simple structure, and long life. The purpose is to provide

[Means to solve problems]

The crucible-type melting furnace according to the present invention, which meets the above objectives,
In a crucible-type melting furnace that heats a crucible by burning fuel and melts the nonferrous metal material in the crucible, a packed bed type preheating chamber having a ventilation tube inside is provided in the flue gas passage. It is constructed by directly preheating the non-ferrous metal material with exhaust gas in a layered preheating chamber.

Here, packed bed type preheating chamber (hereinafter referred to as preheating chamber)
In order to ensure a passage for exhaust gas and a certain heat transfer area, non-ferrous metal material, which is a molten material, is cut or formed into a certain size and length to a certain extent, and then molded.
A preheating chamber whose structure is such that it is filled with material with a certain gap so that hot air, which is exhaust gas, can pass through.

[Effect]

To explain its operation, the crucible-type melting furnace according to the present invention is provided with a preheating chamber in the exhaust gas passage. The preheating chamber is a packed bed preheating furnace in which the exhaust gas directly contacts the molten material, and a ventilation tube is disposed inside the preheating chamber. Of course, the melting material is introduced with a gap provided, but the presence of the ventilation pipe reduces pressure loss and
Since the temperature in the preheating chamber is uniform, the temperature of the melting material located at the bottom does not become high only, and the temperature of all the melting materials is raised uniformly, and the melting material is preheated in a short time. Therefore, within the time it takes to melt a predetermined amount of the melted material in the crucible furnace, which is a small furnace, it becomes possible to preheat the melted material to be introduced into the crucible in the next step. For this reason, as a result, only a single input amount of melting material is required, so the preheating chamber only needs to be in one stage, which means that the size of the crucible-type melting furnace can be reduced as a whole.

The melting material is preheated to near the melting temperature, at which point a significant amount of waste heat is recovered.

〔Example〕

Next, an embodiment embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention. Here, FIG. 1 is a side sectional view of a crucible-type melting furnace according to an embodiment of the present invention.

As shown in the figure, a crucible-type melting furnace 24 according to an embodiment of the present invention includes a crucible furnace 25, a packed bed preheating chamber (hereinafter referred to as a preheating chamber) 26 provided in its exhaust gas passage, and other auxiliary equipment. It is composed of. These will be explained in detail below.

The crucible furnace 25 is a crucible 2 fixed with a support member 27.
8, an air-permeable radiator 29 surrounding the crucible 28, and a furnace wall 30 surrounding the outside of the crucible 28 and insulating the heat. The crucible 28 is adapted to be heated. A space 32 communicating with an exhaust gas duct 31 lined with a refractory is formed on the side of the crucible furnace 25, and a breathable radiator 29 is formed inside the space 32.
is arranged so that the exhaust gas exiting to the exhaust gas duct 31 passes through this breathable radiator 29.

Here, to explain the reason why the breathable radiator 29 is provided, since the breathable radiator 29 is arranged in the exhaust gas passage, it is heated by the high-temperature exhaust gas immediately after heating the crucible 28, and heat radiation is generated. However, this heat radiation is actively utilized to heat the crucible 28, thereby increasing the thermal efficiency of the crucible-type melting furnace 24.

On the other hand, the exhaust gas duct 31 is bent at a right angle outside the crucible furnace 25 so that the exhaust gas flows upward, and a support member 33 is attached to the exhaust gas duct 31 to support the weight of the exhaust gas duct 31. The exhaust gas duct 31 is also provided with a cold air intake 34 for adjusting the temperature of the exhaust gas and a furnace pressure adjustment damper 35 (shown in a closed state in the figure) for adjusting the furnace pressure in the crucible furnace 25. ing. A preheating chamber 26 is provided above the exhaust gas duct 31.

The preheating chamber 26 includes a furnace wall 36 that forms the outer cylinder of the preheating chamber 26 and is lined with a refractory material, and a furnace wall 36 that is disposed below the furnace wall 36 to distribute exhaust gas and prevent the melting material 40 located above from falling. A hot gas distribution grate 37 in the form of a lattice is disposed approximately in the center. It has a ventilation pipe 38 and an outlet 39 for discharging the preheated melting material 40.

The ventilation pipe 38 has a space inside and an opening 38a formed in the lower part of the hot gas distribution grate 3.
7, and is made of a cylinder with many small holes 38b formed around the side so that exhaust gas can freely pass through the inside of the packed bed. Therefore, the ventilation pipe 38 makes the temperature of the preheating chamber 26 uniform, rapidly heating the melting material 40 to a uniform temperature, and also serves to reduce the pressure loss in the exhaust gas passage.

Note that the melting material 40 is preferably filled into the preheating chamber 26 with a gap of about 60% in order to increase the heat transfer area and ensure a passage for exhaust gas. For this reason,
Appropriate protrusions are provided inside the preheating chamber 26 and on the outside of the ventilation pipe 38, and the melted material 4 is fed through the material input port 45, which will be described later.
Even if 0 is freely added, melting material 40 is added at a predetermined interval.
The preheating chamber 26
It is also possible to configure

Further, the discharge port 39 is provided at the lower part of the preheating chamber 26, and when the lid 41 is opened by a handle-type opening/closing mechanism (not shown), the discharge port 39 is heated so that the melted material 40 inside the preheating chamber 26 slides out. The angle of the gas distribution grating 37 and the location of the outlet 39 are determined.

A take-out chute 42 is connected to this discharge port 39.
is disposed, and the melted material 40 is discharged from the discharge port 39.
is put into the crucible 28.

On the other hand, a discharge protrusion 43 is provided at the upper part of the preheating chamber 26 to discharge the exhaust gas after preheating, and a material input port 45 having a lid 44 that can be opened and closed is provided.

Next, how to use the crucible-type melting furnace 24 according to the above embodiment will be explained.

A burner (not shown) at the bottom of the crucible furnace 25 is ignited to heat the crucible 28, and while the non-ferrous metal material placed in the crucible 28 is melting approximately half of the rated capacity of the crucible, the material input port 45 is heated. melting material 40
Insert. Here, the molten material 40 must be formed into a predetermined size by cutting or agglomeration, and furthermore, it must be introduced into the packed bed type preheating chamber 26 with a certain gap. .

After a certain period of time, the melted material 40 is preheated uniformly, so the lid 41 of the discharge port 39 is opened using an opening/closing mechanism (not shown), the preheated melted material 40 is discharged, and the melted material 40 is taken out and put into the crucible furnace 28 through the chute 42. . Thereafter, the preheating chamber 26 is filled with a predetermined amount of the melting material 40 again.

As a result, the preheated molten material 40 is added to the molten nonferrous metal material in the crucible 28, and after a certain period of time,
The melting material 40 will be melted. Thereafter, about half of the molten non-ferrous metal is pumped out using a ladle or the like, and the preheated molten material 40 is put into the crucible 28 again.

The melting material 40 is melted through the above steps, but by preheating the melting material 40 to near the melting temperature, it will be melted in a short time. Therefore, when melting the same amount of melting material 40, This means that a smaller crucible-type melting furnace than conventional ones is sufficient.

In addition, in the above embodiment, the exhaust gas duct 3
1 and the take-out chute 42 are provided separately, but a movable exhaust gas duct is connected to the opening 46 at the top of the crucible, and the preheating chamber is provided in the exhaust gas duct,
The heat distribution grate of the preheating chamber can be opened and closed, and by opening the heat distribution grate, preheated molten material is introduced into the crucible 28, and the structure serves as both an exhaust gas duct and a take-out chute. The present invention is also applicable to a crucible type melting furnace.

[Effect of idea]

The present invention is configured as described above, and it is possible to significantly improve thermal efficiency in a crucible-type melting furnace for non-ferrous metal materials, and to shorten the melting time. Moreover, from this, when melting the same amount of non-ferrous metal material, a smaller crucible-type melting furnace is required than in the past.

In addition, since the preheating chamber is simple and compact, the equipment is cheaper than a conventional crucible-type melting furnace equipped with a preheating device (combustion air preheating device) when melting the same amount of nonferrous metal materials. Since the thermal efficiency is improved and the life of the preheating chamber is long, the operating cost of the crucible-type melting furnace, which is a small furnace, is significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a side view of a crucible-type melting furnace according to an embodiment of the present invention, Fig. 2 is a side sectional view of a conventional crucible-type melting furnace, and Fig. 3 is a side view of a conventional melting furnace with a preheating device. It is a schematic side sectional view. Explanation of symbols, 24... Crucible type melting furnace, 25...
Crucible furnace, 26... Packed bed preheating chamber, 28... Crucible, 29... Breathable radiator, 31... Exhaust gas duct, 38... Ventilation tube, 39... Outlet, 40...
Melting material (non-ferrous metal material), 45...Material input port.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a crucible-type melting furnace that heats a crucible by burning fuel and melts non-ferrous metal materials in the crucible, a ventilation tube is provided inside the flue gas passage. A crucible-type melting furnace characterized in that a packed bed type preheating chamber is provided, and the nonferrous metal material is directly preheated in the packed bed type preheating chamber. (2) The crucible-type melting furnace according to claim 1, which preheats a nonferrous metal material to near the melting temperature in a filling preheating chamber.