Method of recycling oil-containing scrap aluminium for combustion in an aluminium melting furnace

Abstract

The present application relates to a kind of oil-containing circulating waste aluminium in the method for burning in aluminium melting furnace, comprising the following steps: preferentially adding oil-containing scattered waste in combustion raw material when feeding, control 30T, subsequent other combustion raw material is added;First bucket material falls in the center position of hearth, subsequent material falling position is in the side of first bucket material falling position, and material falling position cannot block burner.The present application establishes oil-containing waste burning mode to eliminate equipment safety hazard, realizes the full combustion of oil-containing waste aluminium weak oxidizing property, reduces high-temperature flue gas to be dedusted suction, can reduce the energy consumption and production cost of unit output, can improve the recycling rate of oil-containing waste aluminium resource.

Description

Technical Field

[0001] This invention relates to the field of aluminum melting furnace combustion technology, and in particular to a method for burning oil-containing recycled waste aluminum in an aluminum melting furnace. Background Technology

[0002] Dirty recycled aluminum scrap, baled materials, aluminum foil, and coated materials often carry small amounts of oil. These materials are flammable when fed into the aluminum melting furnace, especially 3003 scrap which has a high oil content. The calorific value of oily substances is much higher than that of ordinary aluminum scrap. Concentrated combustion of these materials can cause localized, instantaneous overheating above the molten pool, leading to a large influx of high-temperature flue gas into the flue. Unburned, sparking plastic and paint particles can enter the dust collector, potentially igniting tarpaulins and aluminum ash, seriously threatening equipment safety. Therefore, establishing an oily waste combustion mode is necessary to eliminate equipment safety hazards and reduce the extraction of high-temperature flue gas by the dust collector. This can lower energy consumption and production costs per unit output, enhancing the company's market competitiveness. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for burning oily recycled waste aluminum in an aluminum melting furnace, so as to achieve complete combustion of the weakly oxidizing oily waste aluminum, reduce the absorption of high-temperature flue gas by dust collectors, and eliminate equipment safety hazards.

[0004] The present invention is implemented by the following scheme: a method for burning oily recycled waste aluminum in an aluminum melting furnace, comprising the following steps: when feeding, oily loose waste from the combustion raw materials is added first, controlled within 30T, and other combustion raw materials are added subsequently; the first bucket of material falls in the center of the furnace, and the subsequent material falls to the side of the first bucket of material falling position, and the falling position should not block the burner.

[0005] Furthermore, after the combustion raw materials are added, do not ignite them immediately. Let the oily waste smolder in the furnace for 10 to 60 minutes before igniting. The waste will spontaneously combust after being baked by the high temperature in the furnace. The coating and oil on its surface will decompose and volatilize. These volatiles will decompose more rapidly during the small fire and undergo secondary combustion in front of the main burner.

[0006] Furthermore, the burner flame air-fuel ratio is controlled at 16:1, and power curves for three sections of the furnace are set: low temperature section ≤800℃, 800℃ < medium temperature section <1000℃, and high temperature section ≥1000℃. The maximum gas flow rates for the three sections are 300Nm3 / h, 500Nm3 / h, and 700Nm3 / h, respectively.

[0007] Furthermore, based on the flame penetration and flue gas conditions at the furnace door, the fume hood valve of the furnace door ambient temperature dust removal system is opened to exhaust smoke, and the burner is started in low-temperature combustion mode at low temperature.

[0008] Furthermore, check whether the inlet temperature of the high-temperature dust removal system in the aluminum melting furnace exceeds 400℃. If it exceeds 400℃, adjust the negative pressure at the end of the high-temperature dust removal pipeline to between -50pa and -100pa.

[0009] Furthermore, when the furnace temperature is ≤800℃, the forming cold air valve automatically switches with the burner combustion. The forming cold air ratio accounts for 20% of the rated air flow, and the combustion hot air ratio accounts for 80% of the rated air flow, ensuring that the oily waste aluminum burns in a weak oxygen environment at low temperature and that the main flame is formed stably and is not easy to extinguish.

[0010] Furthermore, by analyzing the oxygen content of the flue gas, the ratio of air to natural gas is adjusted to reduce the air-fuel ratio as much as possible while ensuring that there is no carbon monoxide in the flue gas.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The present invention establishes an oily waste combustion mode to eliminate equipment safety hazards, realizes the full combustion of weakly oxidizing oily waste aluminum, reduces the absorption of high-temperature flue gas by dust collectors, can reduce energy consumption and production costs per unit output, and can improve the recycling rate of oily waste aluminum resources.

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the burner arrangement in an embodiment of the present invention. Detailed Implementation

[0014] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0015] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0016] A method for burning oil-containing recycled aluminum scrap in an aluminum melting furnace is disclosed. The furnace is a top-opening, round, fixed furnace. The furnace lid is opened and closed using a dedicated lid-opening machine. The furnace is fueled by natural gas, and the burners are high-efficiency, energy-saving regenerative burners that enable rapid melting of solid aluminum. The raw materials for the aluminum melting furnace are solid aluminum materials, mainly including remelted aluminum ingots, recycled aluminum scrap (containing a small amount of oil), and intermediate aluminum alloys. These materials are loaded into the furnace from the top via the lid-opening machine, overhead crane, and charging bucket according to the process requirements. The solid aluminum materials are then melted in the furnace according to the smelting process.

[0017] The process includes the following steps: When feeding, prioritize adding oily, loose waste from the combustion raw materials, keeping the amount below 30 tons, followed by other combustion raw materials; the first bucket of material should fall in the center of the furnace, and subsequent buckets should fall beside the first bucket, ensuring the falling locations do not block the burners. Feeding the loose waste first, followed by larger aluminum pieces, allows the larger aluminum pieces to better press the loose waste into the furnace.

[0018] In this embodiment, after the combustion raw materials are added, the fire is not ignited immediately. The oily waste is allowed to smolder in the furnace for 10 to 60 minutes before ignition. The specific smoldering time depends on the amount of oily waste added. The waste is baked by the high temperature in the furnace and then spontaneously combusts. The coating and oil on its surface will decompose and volatilize. These volatiles decompose rapidly during the small fire and undergo secondary combustion in front of the main burner.

[0019] In this embodiment, the 3003A alloy melting mode is selected on the operation interface of the aluminum melting furnace. To avoid insufficient oxygen content after the oily waste spontaneously combusts, the air-fuel ratio of the burner flame is controlled at 16:1. Power curves for three sections of the furnace are set: low temperature ≤ 800℃, 800℃ < medium temperature < 1000℃, and high temperature ≥ 1000℃. The maximum gas flow rates for the three sections are 300 Nm3 / h, 500 Nm3 / h, and 700 Nm3 / h, respectively. During the specific operation, the combustion power can be finely adjusted based on the smoke situation at the furnace door and the dust removal inlet temperature to solidify the power.

[0020] In this embodiment, based on the flame penetration and flue gas conditions at the furnace door (i.e., when flue gas overflows or flame penetration occurs at the furnace door gap), the fume hood valve of the furnace door ambient temperature dust removal system is opened to exhaust smoke. During the low-temperature stage, the burners are started in low-fire combustion mode (i.e., the maximum gas flow rate is 300 Nm3 / h). Reducing the minimum flow rate of a single main burner can effectively prevent unburned flue gas from being drawn into the dust removal system after the flue gas flow rate is too large. It can also effectively prevent a large amount of high-temperature flue gas from rushing into the flue in a short time due to the auxiliary smoke damper opening too wide, causing the dust removal inlet temperature to exceed the limit.

[0021] In this embodiment, the temperature of the high-temperature dust removal inlet of the aluminum melting furnace is detected to exceed 400°C. If it exceeds 400°C, the negative pressure value at the end of the high-temperature dust removal pipeline is adjusted to between -50pa and -100pa. The frequency of the dust removal fan is automatically adjusted according to the negative pressure value to optimize the furnace combustion system, avoid furnace pressure fluctuations, reduce the opening of the auxiliary smoke damper of the furnace, and lower the dust removal inlet temperature.

[0022] In this embodiment, when the furnace temperature is ≤800℃, the forming cold air valve automatically switches according to the burner combustion. The forming cold air ratio accounts for 20% of the rated air flow, and the combustion hot air ratio accounts for 80% of the rated air flow, ensuring that the oily waste aluminum burns in a weak oxygen environment at low temperature and that the main flame is formed stably and is not easy to extinguish.

[0023] In this embodiment, a furnace temperature control mode is adopted. By analyzing the oxygen content of the flue gas, the air and natural gas ratio is adjusted. Under the premise of ensuring that there is no carbon monoxide in the flue gas, the air-fuel ratio is reduced as much as possible. The air-fuel ratio of the burner flame is adjusted by measuring the air and natural gas flow rates separately.

[0024] This invention eliminates equipment safety hazards by establishing a combustion mode for oily waste. It controls combustion power through different stages of furnace temperature control and manages the air-to-natural gas ratio by analyzing flue gas oxygen content, achieving complete combustion of weakly oxidizing oily waste aluminum and reducing the absorption of high-temperature flue gas by dust collectors. This reduces energy consumption and production costs per unit output, increases the recycling rate of oily waste aluminum resources, effectively reduces primary aluminum ore mining, enhances enterprise market competitiveness, and has significant strategic value for promoting the green and low-carbon transformation of the aluminum industry and achieving sustainable development.

[0025] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0026] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0027] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0028] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for burning oil-containing recycled aluminum in an aluminum melting furnace, characterized in that: Includes the following steps: When feeding, prioritize the addition of oily loose waste materials from the combustion raw materials, keeping the total amount below 30 tons, and then add other combustion raw materials. The first bucket of material should fall in the center of the furnace, and subsequent material should fall to the side of the first bucket's falling position. The falling position should not block the burner.

2. The method for burning oil-containing recycled aluminum in an aluminum melting furnace according to claim 1, characterized in that: After the fuel is fed into the furnace, do not ignite it. Let the oily waste smolder in the furnace for 10 to 60 minutes before igniting. The waste will spontaneously combust after being baked by the high temperature in the furnace. The coating and oil on its surface will decompose and volatilize. These volatiles will decompose faster during the small fire and undergo secondary combustion in front of the main burner.

3. The method for burning oil-containing recycled aluminum in an aluminum smelting furnace according to claim 1, characterized in that: The burner flame air-fuel ratio is controlled at 16:1, and the power curves for the three sections of the furnace—low temperature, medium temperature, and high temperature—are set: low temperature ≤ 800℃, 800℃ < medium temperature < 1000℃, and high temperature ≥ 1000℃. The maximum gas flow rates for the three sections are 300 Nm3 / h, 500 Nm3 / h, and 700 Nm3 / h, respectively.

4. The method for burning oil-containing recycled aluminum in an aluminum smelting furnace according to claim 3, characterized in that: Based on the flame penetration and flue gas conditions at the furnace door, open the fume hood valve of the furnace door ambient temperature dust removal system to exhaust smoke, and start the burner in low-temperature combustion mode during the low-temperature stage.

5. The method for burning oil-containing recycled aluminum in an aluminum melting furnace according to claim 3, characterized in that: Check if the inlet temperature of the high-temperature dust removal system in the aluminum melting furnace exceeds 400℃. If it does, adjust the negative pressure at the end of the high-temperature dust removal pipeline to between -50pa and -100pa.

6. The method for burning oil-containing recycled aluminum in an aluminum melting furnace according to claim 3, characterized in that: When the furnace temperature is ≤800℃, the forming cold air valve automatically switches with the burner combustion. The forming cold air ratio accounts for 20% of the rated air flow, and the combustion hot air ratio accounts for 80% of the rated air flow, ensuring that the oily waste aluminum burns in a weak oxygen environment at low temperature and that the main flame is formed stably and is not easy to extinguish.

7. The method for burning oil-containing recycled aluminum in an aluminum melting furnace according to claim 3, characterized in that: By analyzing the oxygen content in the flue gas, the ratio of air to natural gas is adjusted to reduce the air-fuel ratio as much as possible while ensuring that the flue gas is free of carbon monoxide.

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