Smelting furnace

Abstract

The invention relates to the technical field of direct smelting reduction ironmaking, in particular to a smelting furnace which comprises a furnace body, a molten liquid area, a slag liquid area and a hearth area are sequentially arranged in the furnace body from bottom to top, a material spraying gun is arranged on the side wall of the furnace body, a spraying opening of the material spraying gun is located in the slag liquid area, and the material spraying gun is used for conveying solid raw materials into the slag liquid area through carrier gas. A top spray gun is arranged at the top end of the furnace body, an outlet of the top spray gun is located in the hearth area, the top spray gun is used for inputting oxygen and pulverized coal into the furnace body, and an electric heating device for heating the interior of the furnace body is arranged on the furnace body. According to the technical scheme, within the transition period from carbon metallurgy to hydrogen metallurgy, the proportion of carbon fuel needing to be supplemented by the system can be determined according to the proportion of available hydrogen in total required reducing gas and the proportion of available green electricity heating capacity in total required heating under the limitation of objective conditions such as power consumption cost and insufficient hydrogen supply. Therefore, the method can adapt to each stage in a transitional period. And meanwhile, the process requirements of the hydrogen metallurgy age can also be met.

Description

Technical Field

[0001] This invention relates to the field of direct molten reduction ironmaking technology, specifically a smelting furnace. Background Technology

[0002] Existing direct smelting reduction ironmaking furnaces all rely on oxygen-carbon reaction heating, making them unsuitable for the smelting conversion of carbon to hydrogen. Patent document CN115386671A discloses a simple electromagnetic heating scheme, which is only suitable for situations where green electricity is abundant and its cost is low enough to be marketable. However, the transition from carbon metallurgy to hydrogen metallurgy is actually a process that will take decades due to various limitations such as electricity and hydrogen costs. This process will inevitably involve a gradual decrease in the proportion of carbon metallurgy and an increase in the proportion of hydrogen metallurgy—that is, a gradual replacement of carbon by hydrogen from insufficient to sufficient. However, it can be inferred that even in the hydrogen metallurgy era, the ironmaking process will likely still require the participation of carbon smelting, keeping the furnace temperature 200-300°C lower than that of steelmaking, while using a mixed reducing agent of hydrogen and carbon monoxide to improve ironmaking efficiency.

[0003] The smelting furnace disclosed in patent document CN101956037A, although possessing a combination of electric heating and combustion heating with oxidizing gas and fuel, suffers from extremely low efficiency in this latter method. This is because the solid particles to be heated are added from the top of the furnace, and the heating process occurs while the particles are piled on the surface of the molten material. The convection heating by the hot airflow is almost instantaneous, and the area heated by thermal radiation is limited to the surface of the material pile, resulting in extremely low heat transfer efficiency. Therefore, this solution is practically infeasible and has no practical value.

[0004] Therefore, there is an urgent need for a smelting device that can use both combustion heat and green electricity to adapt to the direct molten reduction ironmaking process at various stages of the transition from carbon metallurgy to hydrogen metallurgy, and also to pure hydrogen ironmaking. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a smelting furnace that can be heated by burning pure oxygen and pulverized coal, as well as by using pure hydrogen to smelt iron and by using green electricity for heating.

[0006] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: A smelting furnace, including a furnace body, The interior of the furnace body, from bottom to top, consists of the molten metal zone, the slag zone, and the furnace chamber. The furnace body is equipped with a spray gun on its side wall, with the spray nozzle located in the slag-liquid zone. The spray gun is used to transport solid raw materials into the slag-liquid zone via a carrier gas. The solid raw materials are mineral powder or pre-reduced mineral powder, coal, solvent, and other solid materials. The carrier gas used by the spray gun can be nitrogen or various reducing gases such as hydrogen. A top spray gun is installed at the top of the furnace body, with its outlet located in the furnace chamber. The top spray gun is used to introduce oxygen and pulverized coal into the furnace body. The furnace body is equipped with an electric heating device for heating the interior of the furnace.

[0007] When hydrogen is used as the carrier gas to feed ore powder or pre-reduced ore powder, solvent, and other solid materials into the furnace, and the furnace is heated by an electric heating device, pure hydrogen smelting can be achieved. When nitrogen is used as the carrier gas to feed ore powder or pre-reduced ore powder, coal, solvent, and other solid materials into the furnace, and oxygen and coal powder are introduced into the furnace through a top spray gun for heating, carbon metallurgy can be achieved. Combining the two methods allows for the simultaneous realization of carbon metallurgy and hydrogen metallurgy, adapting to the direct molten reduction ironmaking processes at various stages of the transition from carbon metallurgy to hydrogen metallurgy.

[0008] This invention injects ore powder and coal into the slag liquid zone through high-pressure carrier gas, so that the splashed molten slag (containing semi-molten solid particles impregnated therein) and the hot air flow of combustion (formed by the combustion of oxygen and pulverized coal delivered by the top spray gun) can transfer heat through convection. At the same time, the specific surface area of ​​the splashed waves and droplets is greatly increased, so that the radiative heat transfer can reach an efficiency level that can maintain the continuous melting and molten reduction.

[0009] Preferably, the electric heating device is a carbon electrode, or the electric heating device is a microwave heating device and / or an electromagnetic induction heating device.

[0010] Preferably, when the electric heating device is a carbon electrode, a solid material feed pipe is provided on the furnace body, and the outlet of the solid material feed pipe is located at the submerged arc of the carbon electrode. The submerged arc refers to the area at the lower end of the carbon electrode covered by the furnace material. Preferably, the carbon electrode is inserted into the furnace body from the top or middle, and the carbon electrode inserted into the furnace body is located in the furnace zone.

[0011] More preferably, two to four carbon electrodes are provided, and a sealing device is provided where the carbon electrodes pass through the furnace body. An air distribution pipe is provided inside the furnace body to protect the carbon electrodes. The air distribution pipe is used to distribute nitrogen cold air in a ring around the carbon electrodes to avoid the carbon electrodes reacting with oxygen, hydrogen and other gases in the furnace gas.

[0012] Preferably, when the electric heating device is a microwave heating device and / or an electromagnetic induction heating device, the furnace body is connected to the preheater, or the furnace body is not connected to the preheater.

[0013] More preferably, the microwave heating device is located on the outer wall of the furnace body corresponding to the furnace chamber area, and is used to heat the furnace chamber area; the electromagnetic induction heating device is located inside the furnace body wall corresponding to the molten liquid area, and is used to heat the molten liquid area.

[0014] Preferably, the top spray gun is equipped with a turbulence element to improve the gas-solid mixing effect, so that the pulverized coal and oxygen-containing gas are fully mixed during the input process and burned in time after entering the furnace, so as to avoid the oxygen-containing gas from contacting the molten iron particles or carbon electrodes.

[0015] A further preferred embodiment has a cooling jacket covering the top spray gun.

[0016] Preferably, the furnace body is connected to a pre-furnace, the bottom of the pre-furnace is connected to the bottom of the furnace body, the top of the pre-furnace is provided with a first iron outlet, and the bottom of the pre-furnace is provided with a second iron outlet.

[0017] Preferably, the upper part of the furnace body is provided with a furnace gas outlet, which is connected to the furnace chamber area.

[0018] Preferably, the furnace body sidewall is provided with a slag outlet, which is connected to the slag-liquid zone.

[0019] More preferably, the furnace body is provided with a cooling wall inside, and the cooling wall is located in the furnace chamber area. The arrangement of the cooling wall can be referred to the arrangement provided in Chinese patent document CN118328713A (application number 202410590120.5).

[0020] Preferably, the lower width of the furnace chamber area is greater than the upper width of the furnace chamber area.

[0021] A further preferred embodiment is that the furnace chamber area of ​​the furnace body has a variable diameter structure that is wider at the bottom and narrower at the top.

[0022] Preferably, the furnace body is composed of a steel plate shell and refractory material disposed inside the steel plate shell, and the furnace body is placed on a furnace base.

[0023] According to this technical solution, during the transition from carbon metallurgy to hydrogen metallurgy, due to objective limitations such as electricity costs and insufficient hydrogen supply, the required proportion of supplemental carbon fuel for the system can be determined based on the proportion of available hydrogen to the total required reducing gas and the proportion of available green electricity heating capacity to the total required heating. Therefore, it can adapt to various stages during the transition period and also meet the process requirements of the hydrogen metallurgy era. Attached Figure Description

[0024] Figure 1 Example 1: A top view of a smelting furnace equipped with electrodes.

[0025] Figure 2 Example 1: Schematic diagram of a cross-section of a smelting furnace AA equipped with electrodes.

[0026] Figure 3 Example 1: Schematic diagram of a cross-section of a smelting furnace BB equipped with electrodes.

[0027] Figure 4 Example 1: Schematic diagram of the CC cross-section of a smelting furnace equipped with electrodes.

[0028] Figure 5 Example 2: Schematic diagram of a smelting furnace equipped with microwave heating and electromagnetic induction heating.

[0029] 1-Furnace body, 2-Slag outlet, 3-Furnace base, 4-Cooling wall, 5-Solid material feed pipe, 6-Carbon electrode, 7-Iron zone, 8-Slag liquid zone, 9-Top spray gun, 12-Furnace chamber, 13-First tapping port, 14-Preheater, 15-Second tapping port, 16-Spray gun, 17-Furnace gas outlet, 18-Microwave heating device, 19-Electromagnetic induction heating device. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Example 1 A smelting furnace, such as Figures 1-4 As shown, the furnace includes a furnace body 1, which consists of a large cylindrical furnace body section, a horizontal ring plate, a small cylindrical furnace body section, and a top plate connected in sequence and seated on a furnace base 3. The exterior is a steel plate shell, and the interior is lined with refractory materials and cooling walls 4. The internal space formed by the furnace body is divided into a lower space for the molten iron zone 7, and then a slag liquid zone 8 and a furnace chamber zone 12, arranged sequentially upwards.

[0032] The inner furnace wall of furnace zone 12 is equipped with a furnace wall cooling device that sprays cold air along the furnace wall. Specifically, cold air is sprayed into the furnace and exits along the furnace wall to protect it. This can be configured as described in CN118328713A, a furnace wall cooling device for an industrial furnace. The incoming cold air is reduced gas that has been processed and recycled back after subsequent processes. The heat absorbed and carried away by the air can be fully utilized in subsequent processes, reducing the heat wasted due to the cooling wall 4, extending the furnace wall's lifespan, and regulating the temperature of the flue gas exiting the furnace.

[0033] The smelting furnace in this embodiment is equipped with two spray guns 16. The spray guns 16 are inserted into the furnace from outside the furnace in the furnace zone 12, with the nozzles inserted below the slag liquid surface in the slag liquid zone 8 and above the molten iron surface in the molten iron zone 7.

[0034] A top spray gun 9 is installed at the top of the furnace body 1 to inject oxygen-containing gas and pulverized coal into the furnace body 1. The central channel of the top spray gun 9 is the oxygen-containing gas channel, the outer ring channel is the pulverized coal channel, and the outermost ring is the cooling water channel. Turbulence-inducing components are installed within the oxygen-containing gas channel. The furnace body also has three carbonaceous electrodes 6. The carbonaceous electrodes 6 are inserted into the furnace zone 12 via a horizontal ring plate between the large and small cylindrical furnace body sections, and are arranged outside the top spray gun 9. Above the carbonaceous electrodes 6, corresponding air distribution pipes are provided to distribute nitrogen gas into a ring around the carbonaceous electrodes 6. A nitrogen sealing device is installed where the carbonaceous electrodes 6 pass through the furnace shell. Next to the three carbonaceous electrodes 6, three solid material feed pipes 5 are respectively installed to feed mineral powder or pre-reduced mineral powder, coal, solvent, and other solid materials, which are distributed and accumulated on the slag liquid surface at the electrode submerged arc.

[0035] The furnace body 1 is also equipped with a preheater 14 and a first tapping port 13. The bottom of the preheater 14 is equipped with a second tapping port 15 for removing molten iron when production is stopped. A slag outlet 2 is provided on the side wall of the furnace body 1 corresponding to the slag liquid zone 8 for removing slag during production.

[0036] The side wall of the small cylindrical furnace body is provided with a furnace gas outlet 17 for the discharge of furnace gas during the production process. During smelting, iron ore powder or pre-reduced iron ore powder, crushed coal, and solvent materials are mixed in a set ratio. Part of the mixture is injected into the molten pool through the injection gun 16 by high-pressure carrier gas (using circulating gas as the carrier gas). The other part is distributed at the submerged arc of the carbon electrode 6 through the solid material feed pipe 5.

[0037] Part of the heat required for smelting is provided by the combustion of pure oxygen from the top lance 9 and pulverized coal. Pulverized coal is fed into the furnace through the pulverized coal channel using nitrogen as the carrier gas. It is thoroughly mixed with the pure oxygen flow after being guided by the turbulence device (generally configured with a certain amount of oxygen deficiency). It burns in the high temperature of the furnace zone 12 with oxygen deficiency, forming more CO and less CO2, while avoiding contact between oxygen and molten iron particles or electrode carbon.

[0038] Another portion of the heating comes from green electricity. The molten iron zone 7 and slag zone 8 are heated primarily by electric arc heating and secondarily by resistance heating through carbon electrodes 6. Nitrogen cooling air is distributed in a ring around the electrode via a distribution duct located above the carbon electrodes 6 to protect them and prevent reaction between the electrodes and oxygen and hydrogen in the furnace gas. Additionally, pressurized nitrogen is injected into the sealing device between the carbon electrodes 6 and the furnace body 1 shell to ensure the furnace gas is sealed during the electrode's vertical movement, preventing leakage.

[0039] The mixture of carbon monoxide, carbon dioxide, and hydrogen produced during the smelting process, along with nitrogen for feeding and sealing, and circulating reducing gas for cooling the furnace walls, are mixed to form high-temperature furnace gas, which is discharged through furnace gas outlet 17 and used in subsequent processes. Molten iron and slag are periodically discharged through the first tapping outlet 13 and the slag outlet 2.

[0040] Example 2 A smelting furnace, such as Figure 5 As shown, the difference from Embodiment 1 is that the furnace body 1 is composed of a cylindrical furnace body structure, a conical furnace body structure, and ring plates connected sequentially and seated on the furnace base 3. The furnace wall air-cooling device, solid material feed pipe 5, carbon electrode 6, and corresponding air distribution pipes and nitrogen sealing device are no longer installed. Instead, a microwave heating device 18 is installed on the outer wall of the furnace body corresponding to the furnace chamber zone 12, and an electromagnetic induction heating device 19 is installed on the furnace wall corresponding to the molten iron zone 7. The electric heating devices use green electricity, and the proportion of electric heating capacity to the total required heating capacity is determined through heat balance based on the amount of coal and oxygen entering the furnace.

Claims

1. A smelting furnace, comprising a furnace body, The interior of the furnace body, from bottom to top, consists of the molten metal zone, the slag zone, and the furnace chamber. The furnace body is equipped with a spray gun on its side wall. The spray gun nozzle is located in the slag-liquid zone. The spray gun is used to transport solid raw materials into the slag-liquid zone via a carrier gas. The carrier gas used by the spray gun is nitrogen or a reducing gas. A top spray gun is installed at the top of the furnace body, with its outlet located in the furnace chamber. The top spray gun is used to introduce oxygen and pulverized coal into the furnace body. The furnace body is equipped with an electric heating device for heating the interior of the furnace.

2. The smelting furnace as described in claim 1, characterized in that, The electric heating device is a carbon electrode, or it is a microwave heating device and / or an electromagnetic induction heating device.

3. The smelting furnace as described in claim 2, characterized in that, When the electric heating device is a carbon electrode, a solid material feed pipe is provided on the furnace body, and the outlet of the solid material feed pipe is located at the submerged arc of the carbon electrode.

4. The smelting furnace as described in claim 2, characterized in that, The carbon electrode is inserted into the furnace body from the top or middle, and the carbon electrode inserted into the furnace body is located in the furnace chamber area.

5. The smelting furnace as described in claim 2, characterized in that, The carbon electrode is provided in two to four parts. A sealing device is provided where the carbon electrode passes through the furnace body. An air distribution pipe is provided inside the furnace body to protect the carbon electrode. The air distribution pipe is used to distribute nitrogen cold air in a ring around the carbon electrode.

6. The smelting furnace as described in claim 2, characterized in that, When the electric heating device is a microwave heating device and / or an electromagnetic induction heating device, the furnace body is connected to the preheater, or the furnace body is not connected to the preheater.

7. The smelting furnace as described in claim 2, characterized in that, The microwave heating device is located on the outer wall of the furnace body, corresponding to the furnace chamber area, and is used to heat the furnace chamber area. The electromagnetic induction heating device is located inside the furnace body wall, corresponding to the molten liquid area, and is used to heat the molten liquid area.

8. The smelting furnace as described in claim 1, characterized in that, It also includes one or more of the following features: The top spray gun is equipped with a baffle to improve the gas-solid mixing effect; The top spray gun is covered with a cooling jacket.

9. The smelting furnace as described in claim 1, characterized in that, It also includes one or more of the following features: The furnace body is connected to a pre-furnace, the bottom of the pre-furnace is connected to the bottom of the furnace body, the top of the pre-furnace is provided with a first iron outlet, and the bottom of the pre-furnace is provided with a second iron outlet. The upper part of the furnace body is provided with a furnace gas outlet, which is connected to the furnace chamber area; The furnace body has a slag outlet on its side wall, which is connected to the slag liquid zone.

10. The smelting furnace as described in claim 1, characterized in that, The furnace body is equipped with a cooling wall located in the furnace chamber area.

11. The smelting furnace as described in claim 1, characterized in that, The lower width of the furnace chamber area of ​​the furnace body is greater than the upper width of the furnace chamber area, or the furnace chamber area of ​​the furnace body has a variable diameter structure that is wider at the bottom and narrower at the top.

12. The smelting furnace as described in claim 1, characterized in that, The furnace body consists of a steel plate shell and refractory material inside the steel plate shell, and the furnace body is placed on the furnace base.

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