CN1322153C - Energy-saving continuous aluminum alloy melting-refining furnace - Google Patents

Abstract

The present invention relates to an energy-saving continuous aluminum alloy melting-refining furnace which comprises a furnace material premelting zone comprising a shaft furnace, an aluminum liquid overheating zone comprising a reverberatory furnace, and a degassing pool and an insulation pool comprising a crucible furnace, and the furnace material premelting zone, the aluminum liquid overheating zone, the degassing pool and the insulation pool are integrated. The energy-saving continuous aluminum alloy melting-refining furnace is characterized in that an oil material or gas burner is installed only in the overheating zone, the outer furnace wall of the reverberatory furnace is circular, one side of the crucible furnace extends into the outer furnace wall of the reverberatory furnace so as to form a public furnace wall separated from the aluminum liquid overheating zone, the degassing pool and the insulation pool in the crucible furnace are separated by the separating wall, an airflow channel communicated with the aluminum liquid overheating zone is arranged above the degassing pool, an aluminum liquid flow inlet communicated with the bottom of a melting pool in the aluminum liquid overheating zone is positioned on the middle part of the degassing pool, and an aluminum liquid channel through which the degassing pool is communicated with the insulation pool is positioned at the bottom of the separating wall. The energy-saving continuous aluminum alloy melting-refining furnace solves the technical problems of the integration of melting and denitrification refining, improvement in heat efficiency, consumption saving, and the assurance of the quality of aluminum liquid.

Description

Energy-saving continuous aluminum alloy melting-refining furnace

Technical field:

The invention relates to a continuous aluminum alloy melting-refining device, in particular to a shaft furnace-type preheating and melting zone, a reverberatory furnace-type molten aluminum superheating zone, and a crucible furnace-type degassing and refining, heat preservation pouring zone. In addition to installing fuel oil or gas burners in the overheating area of the reverberatory furnace type aluminum liquid to heat each area, no fuel or electric energy is used to melt or heat the aluminum liquid, thus saving the heat energy required for preheating and melting of the charge and the removal of the aluminum liquid An energy-saving continuous aluminum alloy melting-refining furnace for the electric energy required for gas refining and heat preservation and the heat loss during the transportation and distribution of aluminum liquid.

Background technique:

With the rapid development of my country's economy, the application of aluminum products is increasing day by day. Melting aluminum, degassing refining, and pouring are the first production steps of many aluminum castings. In general workshops, the electric furnace or reverberatory furnace for melting aluminum and the degassing and holding electric furnace are often arranged in different areas. The molten aluminum flows into the crucible-type degassing furnace from the reverberatory furnace/electric furnace or through the launder or is first filled in the aluminum water ladle, then poured into the electric furnace to adjust the temperature and chemical composition, and then poured after degassing and refining treatment. In such a staged and dispersed melting system, the liquid aluminum is transferred and distributed several times, the temperature rises and falls many times, the heat loss is very large, and the thermal efficiency is very low. Usually, 0.2-0.4 degrees of electricity is needed per kilogram of aluminum liquid to ensure smooth degassing and refining of pouring and other processes. In addition, the molten aluminum is easily oxidized during the transfer process, and inclusions are formed, which reduces the quality of the alloy. At present, my country's power supply is tight. How to improve the thermal efficiency of the aluminum melting system, save electricity, and ensure the quality of castings has always been one of the hot spots in the metallurgical industry.

In the 1980s, someone used the waste heat of the reverberatory furnace to preheat the charge to improve thermal efficiency (R. Strassman: Aluminum furnace and preheat therefore USP04 439 145 March 27, 1984). However, it is still necessary to use an electric furnace to adjust the temperature of the molten aluminum to ensure the smooth progress of degassing and refining, which cannot save electric energy. In order to solve this shortcoming, the inventor of the present application integrated the dry-type reverberatory furnace with the degassing and heat-retaining furnace, canceled the degassing and heat-retaining resistance furnace, simplified the melting process, and saved electric energy. However, the temperature difference between the upper and lower layers of the molten aluminum in the reverberatory furnace pool is very large, sometimes as high as 60-70°C, which is likely to cause intense oxidation and gas absorption of the molten aluminum, resulting in a decline in the quality of aluminum castings. In addition, adding the cold charge directly into the reverberatory furnace is also likely to cause fluctuations in the temperature of the molten aluminum, which brings many difficulties to the process operation. (Energy-saving aluminum alloy continuous melting-degassing furnace, "Special Casting and Nonferrous Alloys", No. 2, 1996, p. 13/17).

At the end of the 1980s, there was a patent in the world to melt aluminum alloy in a shaft furnace to greatly improve the thermal efficiency of molten aluminum (D.Barnes, J.Bass, J.Butler, R.Mckenzie: Vertical shaft furnacemelting aluminum. USP 04844426, 1986 December 10). This type of melting device still needs to use an electric furnace to overheat molten aluminum for degassing and refining operations, which cannot achieve the purpose of saving electricity.

Almost at the same time, a continuous aluminum melting and holding furnace appeared in the world. It integrates a shaft furnace, a reverberatory furnace and a refining and holding furnace, which greatly simplifies the melting process, makes full use of the heat of the gas, and improves the thermal efficiency. (Mitsuhim Nakajima: Metal Melting Holding Furnace. Taiwan Patent Publication No. 134093, May 11, 1990 and 145219, November 1, 1990.) The inner diameter of the shaft furnace of this melting device is cylindrical, and it is easy to shed materials . The temperature of the molten aluminum in the heat preservation pool is maintained by increasing the temperature of the molten aluminum in the superheated zone. The two liquid aluminum outlets/inlets between the superheated area/degassing pool or the degassing pool/insulation pool are almost at the same level. Although the aluminum liquid can flow unimpeded and transfer heat, there is not enough standing time to remove inclusions. Therefore, the quality of castings is difficult to guarantee. Zhan Bingcai proposed an improved structure for these shortcomings. (Taiwan patent announcement No. 275822 on May 11, 1996, the improved structure of the gas continuous melting and holding furnace for aluminum materials (1); ZL patent No. 95224445.4, used on September 27, 1997 for the gas continuous melting and heat preservation of aluminum materials furnace). A static pool is set between the degassing pool/insulation pool, and a honeycomb ceramic filter plate is placed between the static pool/insulation pool to prevent inclusions from mixing into the insulation pool. The temperature of the molten aluminum in these improved degassing and holding furnaces is still maintained by increasing the temperature of the molten aluminum in the overheating zone, and the filter plates must be replaced frequently to filter the molten aluminum and ensure the quality of the alloy. These measures bring many difficulties to the process operation, and cannot guarantee the casting quality and the smooth progress of the melting process. Therefore, in recent years, new continuous aluminum melting furnaces have adopted external (electric or gas) heating degassing and holding furnaces to adjust the temperature of the molten aluminum, and no longer use filter plates to remove inclusions in the molten aluminum (T.Okada, H.Yoshikawa, M.Matsuura, T.Sano, T.Hatanaka: Melting/retaining furnace for aluninum ingot. EP1136778A1, September 26, 2001 and Noh.H.H: Composite melting furnace for aluminum hasa Rostolcasing coupled to the lower part of the melting tower to support theraw material and flow down molten metal. KR2003003299-A January 10, 2003, Derwent No. 2004-312071). But none of these furnace types can save electric energy.

Invention content:

The purpose of the present invention is to provide an energy-saving continuous aluminum alloy melting-refining furnace, which solves the technical problems of integrating preheating, melting, degassing and refining, improving thermal efficiency, saving energy consumption and ensuring the quality of molten aluminum.

The above-mentioned technical problem that the present invention solves is achieved in the following manner:

An energy-saving continuous aluminum alloy melting-refining furnace, which consists of three components: a charge pre-melting zone formed by a shaft furnace, an aluminum liquid overheating zone formed by a reverberatory furnace, and a degassing pool and a holding pool formed by a crucible furnace. Part, which is characterized in that: oil or gas burners are only installed in the superheated area of molten aluminum, and the outer furnace wall of the reverberatory furnace is circular; one side of the semicircular crucible furnace extends into the outer furnace wall of the reverberatory furnace, forming a The common furnace wall separated by the liquid superheating area; the degassing pool and the holding pool in the crucible furnace are separated by a partition wall; above the degassing pool, there is an air flow channel that communicates with the aluminum liquid superheating area, and communicates with the bottom of the melting pool in the aluminum liquid superheating area. The liquid aluminum flow inlet is located in the middle of the degassing pool, and the aluminum liquid channel communicating the degassing pool and the heat preservation pool is located at the bottom of the partition wall.

It is characterized in that it is provided with a nitrogen degassing device that feeds nitrogen into the melting pool of the superheated area of the aluminum liquid and the degassing pool.

It is characterized in that: the common furnace wall between the crucible furnace and the reverberatory furnace and the partition wall in the crucible furnace are heat-conducting refractory materials.

It is characterized in that: the furnace wall of the reverberatory furnace is provided with an air channel connecting the superheated area of molten aluminum to the pre-melted area of charge in the shaft furnace.

The present invention has the following advantages:

1. It can save the power consumption of degassing and refining in the prior art.

2. The temperature of the upper and lower layers of the molten aluminum in the molten pool is uniform, and there is no need to increase the temperature of the molten aluminum in the overheating zone to avoid intense oxidation and air absorption of the molten aluminum.

3. The heat-conducting refractory material partition wall ensures that the heat is transferred from the overheating area to the degassing pool and the heat preservation pool, so that the temperature of the aluminum liquid meets the requirements of degassing and pouring.

4. The aluminum liquid has enough residence time in the degassing tank and moisturizing tank to fully degas and inclusions.

5. Easy to operate, less manpower and equipment investment and high efficiency.

Description of drawings

Figure 1 is a top view of the energy-saving continuous melting-refining furnace body of the present invention.

Fig. 2 is a sectional view of Fig. 1A-A.

Fig. 3 is a sectional view of Fig. 1B-B.

Detailed ways:

The present invention integrates shaft furnace 3, reverberatory furnace 7 and crucible furnace 16, referring to Fig. 1 and 2, constitutes preheating melting zone 2, aluminum liquid overheating zone 8, and degassing pool 12 and holding pool 15, fuel ( Oil or gas) burner (not marked in the figure) is only installed in the aluminum liquid overheating zone 8 of reverberatory furnace 7. The reverberatory furnace 7 is circular to reduce the heat loss from the furnace wall to the surrounding environment. The preheating and melting zone 2 located in the shaft furnace 3 is in the shape of a waist drum, which can prevent shed materials and ensure that the furnace materials fall evenly. The cold metal charge includes aluminum ingots, returned charge and swarf briquettes are put into the furnace from the upper charging port 1 of the shaft furnace 3, and exchange heat with the rising furnace gas during the falling process, the temperature rises gradually, some melt into drops, and some In the semi-molten state, it enters the molten aluminum superheating zone 8 of the reverberatory furnace 7 through the channel 19 at the bottom of the shaft furnace 3, and accumulates at the bottom of the reverberatory furnace 8 through the inclined hearth 20 to form a molten pool 14, and the high-temperature furnace gas burned by the burner is removed In addition to heating the molten aluminum in the molten pool 14, it also escapes in three directions through the furnace cavity of the reverberatory furnace 7, and most of the high-temperature furnace gas enters the bottom of the shaft furnace 3 through the channel 19, and then passes through the preheating melting zone 2 from the gas outlet 4 into the atmosphere. During the rising process of the furnace gas, part of the heat is transferred to the falling aluminum material, heating the metal; the second part of the furnace gas enters the preheating melting zone 2 through the gas channel opening 6 through the gas channel 5 opened in the furnace wall. The furnace wall of the reverberatory furnace 7 is heated, and the aluminum charge is heated again; a small amount of the third part of the furnace gas enters the upper space of the degassing pool 12 through the air flow passage 9 and heats the aluminum liquid. The aluminum liquid usually stays in the aluminum liquid superheating zone 8 for 2-3 hours. A nitrogen degassing device (not shown in the figure) is also provided in the molten aluminum superheating zone 8, and nitrogen gas is passed into the molten aluminum in the molten pool 14, and nitrogen vesicles continuously rise slowly in the molten aluminum in the molten pool 14, slightly Stir the molten aluminum to make the temperature of the upper and lower layers of molten aluminum uniform. The comparison is shown in Table 1, and the effect is very obvious.

Table 1 The effect of nitrogen agitation on the temperature gradient of molten aluminum in the molten aluminum superheated zone

  No nitrogen agitation Nitrogen slight agitation Temperature range and average temperature of upper layer aluminum liquid (814-778) 796 (743-700) 725 The temperature range and average temperature of the lower layer of molten aluminum (760-683) 729 (730-686) 715 Average temperature difference between the upper and lower layers of molten aluminum 67 10

The aluminum liquid is gradually raised to an appropriate temperature, and then flows into the degassing pool 12 from the aluminum liquid outflow port 10 . Can observe furnace condition from furnace door 17, remove slag.

One side of the crucible furnace 16 is extended by a furnace wall made of refractory and heat-conducting material to the common furnace wall in the reverberatory furnace 7 to separate it from the molten aluminum superheating zone 8, and a partition wall 11 of refractory and heat-conducting material is used in the middle to separate the crucible furnace 16 into degassing Pool 12 and insulation pool 15. The molten aluminum inflow port 10, which is arranged on the above-mentioned common furnace wall and communicates with the bottom of the melting pool 14 in the molten aluminum superheating zone 8, is located in the middle of the wall of the degassing pool 12 (see Figure 3). The degassing pool 12 is equipped with a nitrogen device (not shown in the figure), which can continuously or intermittently degas the aluminum liquid. The lower end of the partition wall 11 between the degassing pool 12 and the heat preservation pool 15 is provided with an aluminum liquid flow port 13 . The aluminum liquid inflow port 10 and the aluminum liquid flow port 13 are not at the same height, nor in the same direction. This drop ensures that after the molten aluminum pours into the degassing tank 12 from the superheated zone 8 of the molten aluminum, there is enough time (20-30 minutes) to interact with the small nitrogen bubbles rising from the bottom of the tank during the downward flow process to obtain degassing. refining. The partition wall 11 plays a role in preventing slag and inclusions from entering the heat preservation pool 15 and contaminating the molten aluminum again. The refined aluminum liquid enters the bottom of the heat preservation tank 15 from the aluminum liquid circulation port 13, and there is enough time (40-50 minutes) to continue to remove inclusions during the rising process of the aluminum liquid. Finally, the cleaned aluminum liquid rises to the liquid level and is ready for pouring. There is an airflow channel 9 on the upper side of the degassing pool to communicate with the superheated area. Like this, the molten aluminum in the degassing pool 12 and the heat preservation pool 15 can obtain heat from the following three aspects,

(1) A large amount of high-temperature aluminum melt continuously pours into the degassing pool from the molten aluminum hot zone 8, bringing heat;

(2) The high-temperature furnace gas enters the upper space of the degassing pool 12 from the air flow channel 9, and heats the metal melt;

(3) The heat of the molten aluminum superheating zone furnace and the molten pool 14 is transmitted to each pool of molten aluminum through the heat conduction material furnace wall shared with the crucible furnace 16, heating the molten metal, effectively slowing down the decline of the molten aluminum temperature, and ensuring them It has an appropriate temperature to meet the needs of each process.

Below through specific embodiment, further set forth substantive characteristic and remarkable progress of the present invention, but the present invention is by no means limited to embodiment.

Example:

The existing continuous aluminum melting furnace melts 500 kilograms of aluminum per hour. Two heavy oil burners are installed in the overheating area, and the fuel consumption is 20 kg per hour. Three 30 kW resistance furnaces (each containing 500 kg of aluminum water) are used to operate simultaneously. After adjusting the temperature of the aluminum liquid to 700 ° C, the aluminum liquid is degassed with nitrogen. After slag removal and standing still, the blanks of auto parts are poured. This operation takes about 3 hours. The power consumption per kilogram of aluminum alloy is about 0.20 degrees. After changing the structure of the present invention, it can guarantee to obtain the suitable temperature of molten aluminum (see Table 2), thereby canceling the resistance furnace, and saving 200 kwh of electricity per ton of molten aluminum.

Table 2 Temperature of molten aluminum in different parts ℃

superheated area degas pool pouring pool Temperature range (738-713) average temperature 729 (721-715) 713 (704-695) 698

Claims (5)

1. An energy-saving continuous aluminum alloy melting-refining furnace, including a charge pre-melting zone formed by a shaft furnace, an aluminum liquid overheating zone formed by a reverberatory furnace, and a degassing pool and a holding pool formed by a crucible furnace. It is a component part, characterized in that: oil or gas burners are only installed in the superheated area of molten aluminum, and the outer furnace wall of the reverberatory furnace is circular; one side of the crucible furnace extends into the outer furnace wall of the reverberatory furnace to form a superheated area with molten aluminum Separated common furnace wall; the degassing pool and heat preservation pool in the crucible furnace are separated by a partition wall; above the degassing pool there is an air flow channel that communicates with the superheated area of molten aluminum, and the molten aluminum flow that communicates with the bottom of the molten pool in the superheated area of molten aluminum The entrance is located in the middle of the degassing pool, and the aluminum liquid channel communicating the degassing pool and the heat preservation pool is located at the bottom of the partition wall. 2. The energy-saving continuous aluminum alloy melting-refining furnace according to claim 1, characterized in that it is equipped with a molten pool for passing nitrogen into the superheated area of molten aluminum, and a nitrogen degassing device in the degassing pool. 3. The energy-saving continuous aluminum alloy melting-refining furnace according to claim 1, characterized in that: the common furnace wall between the crucible furnace and the reverberatory furnace and the partition wall in the crucible furnace are made of heat-conducting refractory materials. 4. The energy-saving continuous aluminum alloy melting-refining furnace according to claim 2, characterized in that: the common furnace wall between the crucible furnace and the reverberatory furnace and the partition wall in the crucible furnace are made of heat-conducting refractory materials. 5. The energy-saving continuous aluminum alloy melting-refining furnace according to claim 1, 2, 3 or 4, characterized in that: the furnace wall of the reverberatory furnace is provided with a furnace connecting the superheated area of molten aluminum to the charge preheating zone in the shaft furnace. Airways in the melting zone.

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