Electric furnace flue gas waste heat utilization system

Abstract

The utility model discloses an electric furnace flue gas waste heat utilization system which comprises an electric furnace, a fourth hole outlet, a heat insulation flue, a settling chamber, a waste heat recovery device and a connecting flue between the electric furnace, the fourth hole outlet, the heat insulation flue, the settling chamber and the waste heat recovery device. One channel is respectively communicated with a flue gas inlet flue and a flue gas outlet flue which are connected out of the settling chamber, the other channel is respectively and correspondingly communicated with a heat exchange air inlet and a heat exchange air outlet, and the heat accumulator is arranged on the rotor and is driven by the rotor to rotate so as to convert the positions of the two channels and exchange heat; and the heat storage body rotates for a circle to finish heat absorption and heat release of one cycle. The waste heat recovery device exchanges heat with air, so that the utilization rate of flue gas waste heat of the electric furnace is improved. The flue gas waste heat of the electric furnace can be effectively recycled, stable hot air is generated and supplied to a hot blast stove of a steel mill for smelting, and heat energy is safely and effectively recycled under the condition that normal production of the electric furnace is not affected.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial waste heat recovery and utilization, in particular to a waste heat utilization system for electric furnace flue gas. Background Art

[0002] Due to the outstanding advantages of electric furnace steelmaking, such as short process, low investment, fast construction, and good energy conservation and emission reduction effects, the number of electric furnaces has developed rapidly in recent years. The process of smelting a furnace of steel in an electric furnace includes charging, oxygen blowing, decarburization, deoxidation and dealloying, and tapping. The amount of flue gas generated and the flue gas temperature vary at different process stages and also change with the smelting cycle, which is about 35 - 45 minutes for one steelmaking cycle. The amount of electric furnace flue gas is also closely related to the amount of hot metal charged and the amount of oxygen blown in the smelting process. The electric furnace flue gas has a high dust content, and the contained iron oxide dust has industrial recycling value. The heat carried by the high-temperature dusty flue gas is about 11% of the total input energy of the electric furnace, and in some cases, it can even be as high as 20%. These high-temperature flue gases not only carry away a large amount of heat but also bring a huge burden to the dust removal system of the electric furnace, reducing the recovery rate of iron oxide dust.

[0003] Existing electric furnace waste heat boilers produce saturated steam, which only provides saturated steam for power generation after passing through a heat accumulator, resulting in low power generation efficiency. In the prior art, there are cases where a waste heat furnace is coupled with molten salt heat storage for power generation, which can, to a certain extent, eliminate the periodic fluctuations of the electric furnace flue gas. However, the molten salt system has a high investment, and the control system needs to be adjusted according to the changes in the flue gas cycle, which requires a high level of the system and is difficult to be widely promoted and applied on a large scale. Summary of the Utility Model

[0004] To solve the above technical problems, the utility model designs a waste heat utilization system for electric furnace flue gas to solve the problems such as the periodic fluctuations of the flue gas and the complexity of the control system mentioned above.

[0005] The utility model adopts the following technical solutions:

[0006] A waste heat utilization system for electric furnace flue gas includes an electric furnace, a fourth-hole outlet, an adiabatic flue, a sedimentation chamber, a waste heat recovery device, and the connecting flues therebetween. The waste heat recovery device includes a heat storage body and a rotor. The heat storage body is separated by a transition section into two channels. One channel is respectively connected to the flue gas inlet flue and the flue gas outlet flue connected to the sedimentation chamber, and the other channel is respectively connected to the heat exchange air inlet and the heat exchange air outlet. The heat storage body is installed on the rotor and is driven by the rotor to rotate, so as to convert the positions of the two channels and conduct heat exchange. One cycle of heat absorption and heat release is completed when the heat storage body rotates one week.

[0007] Preferably, heat storage bricks with pores are arranged inside the heat storage body.

[0008] Preferably, the heat storage material of the heat storage body is a ceramic heat storage body or a magnesite brick. It can also be other forms of heat storage media.

[0009] Preferably, a castable is laid on the outside of the heat storage body for heat preservation.

[0010] Preferably, a sealing device is arranged at the interface positions between the heat storage body and the flue gas inlet flue, the flue gas outlet flue, the heat exchange air inlet and the heat exchange air outlet.

[0011] Preferably, the rotor is driven to rotate by a motor and a transmission device. The high-temperature air generated by the heat exchange between the low-temperature air and the electric furnace flue gas can be supplied to the hot blast stove of the steel mill, saving energy.

[0012] The beneficial effects of the present utility model are as follows: The present utility model provides a system for utilizing the waste heat of electric furnace flue gas. The high-temperature flue gas discharged from the fourth hole of the electric furnace enters the waste heat recovery device through the adiabatic flue and the sedimentation chamber, exchanges heat with air, and improves the utilization rate of the waste heat of the electric furnace flue gas. The waste heat of the electric furnace flue gas can be effectively recovered, stable hot air can be generated, and it can be supplied to the steel mill hot blast stove for smelting. Without affecting the normal production of the electric furnace, heat energy can be safely and effectively recovered. Description of the Drawings

[0013] Figure 1 It is a structural schematic diagram of the present utility model;

[0014] In the figure: 1, electric furnace; 2, fourth hole outlet; 3, adiabatic flue; 4, sedimentation chamber; 5, flue gas inlet flue; 6, flue gas outlet flue; 7, heat exchange air outlet; 8, heat exchange air inlet; 9, heat storage body; 10, rotor. Detailed Embodiments

[0015] The following will further specifically describe the technical solutions of the present utility model through specific embodiments in conjunction with the drawings:

[0016] Embodiment: As Figure 1 shown, a system for utilizing the waste heat of electric furnace flue gas includes an electric furnace 1, a fourth hole outlet 2, an adiabatic flue 3, a sedimentation chamber 4, a waste heat recovery device and the connecting flues therebetween. The waste heat recovery device includes a heat storage body 9 and a rotor 10. The heat storage body is separated by a transition section and is divided into two channels. One channel is respectively connected to the flue gas inlet flue 5 and the flue gas outlet flue 6 led out from the sedimentation chamber, and the other channel is respectively correspondingly connected to the heat exchange air inlet 8 and the heat exchange air outlet 7. The heat storage body is installed on the rotor and is driven by the rotor to rotate to perform the position conversion of the two channels and exchange heat. When the heat storage body rotates one week, a cycle of heat absorption and heat release is completed.

[0017] Heat storage bricks with pores are arranged inside the heat storage body. The heat storage material of the heat storage body is a ceramic heat storage body or magnesite brick. It can also be other forms of heat storage media. A castable is laid on the outside of the heat storage body for heat preservation.

[0018] Sealing devices are arranged at the interface positions of the regenerator with the flue gas inlet duct, the flue gas outlet duct, the heat exchange air inlet, and the heat exchange air outlet. The rotor is driven to rotate by a motor and a transmission device.

[0019] As Figure 1 shown, the exhaust flue of the electric furnace is usually called the fourth-hole exhaust. The flue gas flow rate and temperature both fluctuate with the electric furnace steelmaking cycle. The electric furnace flue gas enters the settling chamber through the fourth-hole outlet via the adiabatic flue, where the combustion of combustible gases and the sedimentation of ash particles are completed. The flue gas enters the rotor regenerator for heat exchange through the inlet flue, flows downward through the regenerator bricks in half (180°) of the regenerator. The high-temperature flue gas transfers heat to the regenerator and its temperature drops below 200°C and then flows out through the flue gas outlet duct. When the flue gas flows through the regenerator bricks in the rotating rotor, it transfers heat to the regenerator bricks, raising their temperature. Finally, the flue gas enters the dust collector for dust removal. Cold air, under the action of the blower, enters the rotor regenerator for heat exchange from the lower part on the other side, flows through a 120° range of the rotating rotor, scours the regenerator bricks that have been heated by the flue gas, absorbs the heat of the regenerator to raise the air temperature, and finally is introduced into the hot blast stove through the air outlet to complete the waste heat recovery of the entire electric furnace flue gas.

[0020] The rotor regenerator is radially partitioned into 12 non-venting large compartments (each compartment is 30°, and there are also small compartments inside) from top to bottom. There is a 30° transition interval between the flue gas and the air, where neither air nor flue gas flows, so the flue gas and the air will not mix. To prevent air from leaking into the flue gas, there are sealing devices between the air inlet and outlet, the flue gas inlet and outlet, and the rotor, and there is also a sealing device between the rotor and the outer shell. There is castable insulation outside the regenerator.

[0021] The above-described embodiments are only a preferred solution of the present invention, and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions described in the claims.

Claims

1. An electric furnace flue gas waste heat utilization system, comprising an electric furnace, a fourth outlet, an insulated flue, a settling chamber, a waste heat recovery device and a connecting flue therebetween, characterized in that: The waste heat recovery device includes a heat storage body and a rotor. The heat storage body is separated by a transition section and is divided into two channels. One channel is respectively connected to the flue gas inlet flue and the flue gas outlet flue connected to the settling chamber, and the other channel is respectively connected to the heat exchange air inlet and the heat exchange air outlet. The heat storage body is installed on the rotor and is driven to rotate by the rotor to switch the positions of the two channels and perform heat exchange. The heat storage body completes a cycle of heat absorption and heat release when it rotates one circle.

2. The electric furnace flue gas waste heat utilization system according to claim 1 is characterized in that: The heat storage bricks with pores are arranged inside the heat storage body.

3. The electric furnace flue gas waste heat utilization system according to claim 1 is characterized in that: The heat storage material of the heat storage body is a ceramic heat storage body or a magnesium brick.

4. The electric furnace flue gas waste heat utilization system according to claim 1 is characterized in that: The outer side of the heat storage body is provided with casting material for heat preservation.

5. The electric furnace flue gas waste heat utilization system according to claim 1 is characterized in that: Sealing devices are arranged at the interface positions between the heat storage body and the smoke inlet flue, the smoke outlet flue, the heat exchange air inlet and the heat exchange air outlet.

6. The electric furnace flue gas waste heat utilization system according to claim 1 is characterized in that: The rotor is driven to rotate by the motor and the transmission device.

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