Electric furnace steelmaking high-temperature flue gas preheating scrap steel system

Abstract

This utility model discloses a high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking, including a conveyor, a preheating chamber, a combustion chamber, a discharge valve, a discharge chute, an electric arc furnace, a high-temperature flue, a medium-temperature gas pipe, and a flue gas emission device. A conveyor is installed at the upper end of the preheating chamber, and a combustion chamber is located on the lower outer side of the preheating chamber. Burners are installed on the inner side of the combustion chamber, which is connected to the interior of the preheating chamber via a flue gas channel on the lower side of the preheating chamber. A discharge valve is installed at the lower end of the preheating chamber. A discharge chute and a high-temperature flue are installed on the furnace cover of the electric arc furnace. The discharge chute is connected to the discharge valve, and the high-temperature flue is connected to the interior of the combustion chamber via a flue gas channel on the bottom surface of the combustion chamber. A medium-temperature gas pipe is installed on the upper side of the preheating chamber. A fume hood is installed on the furnace cover and outer side of the furnace shell of the electric arc furnace. Both the medium-temperature gas pipe and the fume hood are connected to the flue gas emission device. This system can preheat scrap steel using the high-temperature flue gas generated during the electric arc furnace steelmaking process, thereby reducing steelmaking energy consumption.

Description

Technical Field

[0001] This utility model relates to electric arc furnace steelmaking, and in particular to a system for preheating scrap steel using high-temperature flue gas generated during the electric arc furnace steelmaking process. Background Technology

[0002] Electric arc furnace steelmaking is an important part of my country's steel industry. Short-process steelmaking has advantages such as short production process, low project investment, low energy consumption, and low carbon emissions.

[0003] According to relevant statistics, the main processes in the long-process production of 1 ton of molten steel consume 432.84 kgce and emit 1.515 tons of carbon, while the short-process process consumes 229.63 kgce and emits 0.804 tons of carbon. It is evident that the short-process smelting has a very significant significance in energy conservation and carbon reduction.

[0004] Compared to long-process steelmaking, short-process steelmaking mainly suffers from two problems: high scrap steel prices and high electricity consumption in the smelting process. In the future, with the increase in scrap steel reserves, scrap steel prices will be further alleviated. Therefore, high energy consumption in electric arc furnace (EAF) smelting is a major issue affecting the industry's technological development. Currently, the electricity consumption per ton of steel produced by EAF smelting in my country is nearly 500 kWh, which is the main cost of short-process steelmaking. EAF smelting temperatures reach as high as 1600℃, generating a large amount of flue gas, which is currently mostly directly released into the atmosphere in China. The energy consumption of conventional EAF steelmaking generally includes 50% heat energy consumed by molten steel, 22% by flue gas, and 6% by slag. If all the 22% heat energy consumed by flue gas could be recovered and utilized, it is expected that the electricity consumption per ton of steel produced by EAF could be reduced to below 300 kWh, which has significant energy-saving and carbon-reduction implications. Summary of the Invention

[0005] Purpose of the utility model: This utility model provides a system that can preheat scrap steel with high-temperature flue gas generated during the electric arc furnace steelmaking process to reduce steelmaking energy consumption.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking includes a conveyor, a preheating chamber, a combustion chamber, a discharge valve, a discharge chute, an electric arc furnace, a high-temperature flue, a medium-temperature gas pipe, and a flue gas emission device. A conveyor is installed at the upper end of the preheating chamber, and a combustion chamber is located on the lower outer side of the preheating chamber. Burners are installed on the inner side of the combustion chamber. The combustion chamber is connected to the interior of the preheating chamber via a flue gas passage on the lower side of the preheating chamber. A discharge valve is installed at the lower end of the preheating chamber. A discharge chute and a high-temperature flue are installed on the furnace cover of the electric arc furnace. The discharge chute is connected to the discharge valve. The high-temperature flue is connected to the interior of the combustion chamber via a flue gas passage on the bottom surface of the combustion chamber. A medium-temperature gas pipe is installed on the upper side of the preheating chamber. A fume hood is installed on the outer side of the furnace cover and furnace shell of the electric arc furnace, and a gas pipe is installed on the fume hood. Both the medium-temperature gas pipe and the gas pipe are connected to the flue gas emission device.

[0007] Furthermore, the preheating chamber is in the shape of a vertical cylinder, the combustion chamber is arranged in a ring along the outer side of the preheating chamber, multiple burners are evenly distributed in the combustion chamber, steel plates are installed on the outer side of the preheating chamber and the combustion chamber, and a fire-resistant insulation layer is installed on the inner side of the preheating chamber and the combustion chamber, and the thickness of the fire-resistant insulation layer is not less than 100mm.

[0008] Furthermore, the unloading valve is an electric unloading valve, and a fire-resistant insulation layer is provided at the bottom of the unloading valve, with a thickness of not less than 150mm.

[0009] Furthermore, the furnace cover and furnace shell of the electric arc furnace are equipped with a refractory insulation layer, and the thickness of the refractory insulation layer is not less than 180mm.

[0010] Furthermore, a heat exchanger is installed in the middle of the medium-temperature gas pipe.

[0011] Furthermore, the heat exchanger is a steam heat exchanger.

[0012] Furthermore, a fire-resistant insulation layer is installed inside the high-temperature flue, and the thickness of the fire-resistant insulation layer is not less than 150mm. Insulation cotton is installed on the outside of the medium-temperature gas pipe, and the thickness of the insulation cotton is not less than 50mm.

[0013] Furthermore, the gas emission device includes a dust collector, a fan, and a chimney connected in sequence.

[0014] Furthermore, the dust collector is a bag filter dust collector, and the fan is a variable frequency fan.

[0015] Furthermore, the conveyor is a plate chain conveyor.

[0016] Beneficial effects: This system realizes the utilization of waste heat from high-temperature flue gas generated during electric arc furnace smelting. It replaces traditional flue gas treatment processes with combustion and preheating chambers, using counter-current heat exchange between the high-temperature flue gas and scrap steel. This heats the scrap steel while simultaneously lowering the temperature of the high-temperature flue gas, creating conditions for low-energy electric arc furnace smelting. The system has a small footprint, good airtightness, low investment, reliable operation, and high waste heat recovery efficiency. Attached Figure Description

[0017] Figure 1 Schematic diagram of a high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking.

[0018] In the diagram: 1-Scrap steel; 2-Conveyor; 3-Preheating chamber; 4-Combustion chamber; 5-Burn; 6-Discharge valve; 7-Discharge chute; 8-Furnace cover; 9-Furnace shell; 10-Electrode; 11-Fumigation hood; 12-High-temperature flue; 13-Medium-temperature gas pipe; 14-Heat exchanger; 15-Gas pipe; 16-Dust collector; 17-Fan; 18-Chimney. Detailed Implementation

[0019] The present invention will be further explained below with reference to the accompanying drawings.

[0020] like Figure 1 As shown, the present invention discloses a high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking, comprising a conveyor 2, a preheating chamber 3, a combustion chamber 4, a discharge valve 6, a discharge chute 7, an electric arc furnace, a high-temperature flue 12, a medium-temperature gas pipe 13, and a flue gas emission device. A conveyor 2 is installed at the upper end of the preheating chamber 3. A combustion chamber 4 is installed on the lower outer side of the preheating chamber 3. A burner 5 is installed on the inner side of the combustion chamber 4. The combustion chamber 4 is connected to the interior of the preheating chamber 3 through a flue gas passage on the lower side of the preheating chamber 3. A discharge valve 6 is installed at the lower end of the preheating chamber 3. A discharge chute 7 and a high-temperature flue 12 are installed on the furnace cover 8 of the electric arc furnace. The discharge chute 7 is connected to the discharge valve 6. The high-temperature flue 12 is connected to the interior of the combustion chamber 4 through a flue gas passage on the bottom surface of the combustion chamber 4. A medium-temperature gas pipe 13 is installed on the upper side of the preheating chamber 3. A fume hood 11 is installed on the outer side of the furnace cover 8 and the furnace shell 9 of the electric arc furnace. A gas pipe 15 is installed on the fume hood 11. Both the medium-temperature gas pipe 13 and the gas pipe 15 are connected to the flue gas emission device.

[0021] The conveyor 2 is a plate chain conveyor used to feed scrap steel 1 to the upper part of the preheating chamber 3. The main body of the conveyor 2 is made of steel and can withstand long-term operating temperatures of not less than 300℃. The preheating chamber 3 is a vertical cylindrical shape used to heat the scrap steel. The combustion chamber 4 is arranged in a ring around the outside of the preheating chamber 3 for secondary combustion and heat release of the electric furnace flue gas. Multiple burners 5 are evenly distributed in the combustion chamber 4 to ignite the high-temperature flue gas entering the combustion chamber. Steel plates are installed on the outside of the preheating chamber 3 and the combustion chamber 4, and refractory insulation layers are installed on the inside of the preheating chamber 3 and the combustion chamber 4, with a thickness of not less than 100mm. The unloading valve 6 is an electric unloading valve. The main body of the electric unloading valve is made of heat-resistant steel. A refractory insulation layer is installed at the bottom of the unloading valve 6 near the unloading trough 7, with a thickness of not less than 150mm. The furnace cover of the electric arc furnace is used to cover the furnace shell and has protective functions such as heat preservation and preventing molten steel from overflowing. The furnace cover 8 and furnace shell 9 of the electric arc furnace are both made of steel. A refractory insulation layer is installed inside the furnace cover 8 and furnace shell 9, and the thickness of the refractory insulation layer is not less than 180mm. The fume hood 11 covers the furnace cover 8, furnace shell 9, as well as the unloading chute 7 and electrodes 11 located on the furnace cover 8, providing dust removal and good sealing conditions for the system. The main body of the fume hood 11 is made of steel.

[0022] A heat exchanger 14 is installed in the middle of the medium-temperature gas pipe 13. The heat exchanger 14 is a steam heat exchanger that can withstand a steam pressure of not less than 1.0 MPa. The heat exchanger 14 is used for cooling the flue gas after preheating the scrap steel before it enters the dust collector. A fire-resistant insulation layer is installed inside the high-temperature flue 12, and the thickness of the fire-resistant insulation layer is not less than 150 mm. The medium-temperature gas pipe 13 and the gas pipe 15 are installed with insulation cotton on the outside, and the thickness of the insulation cotton is not less than 50 mm.

[0023] The exhaust system includes a dust collector 16, a fan 17, and a chimney 18 connected in sequence. The dust collector 16 is a bag filter, and the fan 17 is a variable frequency fan. The chimney 18 is a steel or reinforced concrete structure chimney.

[0024] The working process of the high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking is as follows: High-temperature flue gas (900–1500°C) generated by electric furnace smelting enters combustion chamber 4 through the gaps between furnace shell 9, furnace cover 8, and electrodes 10, and through high-temperature flue 12, under the negative pressure of blower 17. It is ignited by burners 5 within combustion chamber 4, causing secondary combustion of the CO attached to the high-temperature flue gas, further releasing the chemical heat in the flue gas, raising its temperature to 1600–2200°C. Scrap steel 1 is transported by conveyor 2 to the top of preheating chamber 3 and continues to descend as it is unloaded by discharge valve 6. The high-temperature flue gas after secondary combustion rises from the bottom of preheating chamber 3 under the negative pressure of blower 17. As the scrap steel 1 descends, it encounters the high-temperature flue gas, causing its temperature to rise continuously. As the flue gas rises, it heats the descending scrap steel, causing its temperature to continuously decrease. The scrap steel 1, preheated to 600-1200℃ in the preheating chamber 3, is fed into the electric furnace according to the charging system. The scrap steel 1 falls into the electric furnace smelting pool inside the furnace shell 9 through the unloading valve 6 and the unloading chute 7. The power consumption for heating 1 ton of scrap steel is less than 300 kWh. After the high-temperature flue gas completes the preheating of the scrap steel, its temperature decreases. It is then fed into the heat exchanger 14 through the medium-temperature gas pipe 13 and further cooled to 200-600℃. Then, it is transported together with the dust removal gas in the fume hood 11 through the gas pipe 15 to the dust collector 16 for dust removal. The temperature of the flue gas after dust removal is reduced to below 180℃, and finally discharged through the fan 17 and the chimney 18 in compliance with standards.

[0025] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A system for preheating scrap steel with high-temperature flue gas from electric steelmaking, characterized in that it comprises: The system includes a conveyor (2), a preheating chamber (3), a combustion chamber (4), a discharge valve (6), a discharge chute (7), an electric arc furnace, a high-temperature flue (12), a medium-temperature gas pipe (13), and a flue gas emission device. A conveyor (2) is installed at the upper end of the preheating chamber (3), and a combustion chamber (4) is installed on the lower outer side of the preheating chamber (3). A burner (5) is installed on the inner side of the combustion chamber (4). The combustion chamber (4) is connected to the interior of the preheating chamber (3) through a flue gas passage on the lower side of the preheating chamber (3). A discharge valve (6) is installed at the lower end of the preheating chamber (3). A discharge chute (7) and a high-temperature flue (12) are provided on the furnace cover (8) of the electric arc furnace. The discharge chute (7) is connected to the discharge valve (6). The high-temperature flue (12) is connected to the interior of the combustion chamber (4) through the flue gas passage on the bottom surface of the combustion chamber (4). A medium-temperature gas pipe (13) is provided on the upper side of the preheating chamber (3). A smoke hood (11) is provided on the outside of the furnace cover (8) and the furnace shell (9) of the electric arc furnace. A gas pipe (15) is provided on the smoke hood (11). The medium-temperature gas pipe (13) and the gas pipe (15) are both connected to the flue gas emission device.

2. The system for preheating scrap steel by using high-temperature flue gas of electric furnace steelmaking according to claim 1, characterized in that: The preheating chamber (3) is in the shape of a vertical cylinder, and the combustion chamber (4) is arranged in a ring along the outside of the preheating chamber (3). Multiple burners (5) are evenly distributed in the combustion chamber (4). Steel plates are installed on the outside of the preheating chamber (3) and the combustion chamber (4). A fire-resistant insulation layer is installed on the inside of the preheating chamber (3) and the combustion chamber (4), and the thickness of the fire-resistant insulation layer is not less than 100mm.

3. The system for preheating scrap steel by using high-temperature flue gas of electric furnace steelmaking according to claim 1, characterized in that: The unloading valve (6) is an electric unloading valve. A fire-resistant insulation layer is provided at the bottom of the unloading valve (6), and the thickness of the fire-resistant insulation layer is not less than 150mm.

4. The high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking according to claim 1, characterized in that: The furnace cover (8) and furnace shell (9) of the electric arc furnace are equipped with a refractory insulation layer, and the thickness of the refractory insulation layer is not less than 180mm.

5. The high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking according to claim 1, characterized in that: A heat exchanger (14) is installed in the middle of the medium-temperature gas pipe (13).

6. The electric arc furnace steelmaking high-temperature flue gas preheating scrap system according to claim 5, characterized in that: The heat exchanger (14) is a steam heat exchanger.

7. The high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking according to claim 1, characterized in that: The high-temperature flue (12) is equipped with a fire-resistant insulation layer inside, and the thickness of the fire-resistant insulation layer is not less than 150mm. The medium-temperature gas pipe (13) and gas pipe (15) are equipped with insulation cotton on the outside, and the thickness of the insulation cotton is not less than 50mm.

8. The high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking according to claim 1, characterized in that: The gas emission device includes a dust collector (16), a fan (17), and a chimney (18) connected in sequence.

9. A high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking according to claim 8, characterized in that: The dust collector (16) is a bag filter, and the fan (17) is a variable frequency fan.

10. A high-temperature flue gas preheating scrap steel system for electric arc furnace steelmaking according to claim 1, characterized in that: The conveyor (2) is a plate chain conveyor.

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