Low-carbon metal smelting system powered by fuel gas

Abstract

The utility model provides a low-carbon metal smelting system powered by fuel gas, which is characterized in that a gas-based shaft furnace is used for reducing to-be-reduced mineral aggregate input by an input end to obtain direct reduced metal and shaft furnace gas; the shaft furnace gas is sequentially subjected to cooling and decarburization treatment through a heat exchange device and a carbon capture device, and shaft furnace gas decarburization gas is obtained; the multi-tuyere side-blown melt separation furnace directly reduces metal on the basis of flux melt separation treatment, required energy is provided through fuel gas, shaft furnace gas decarburized gas and oxygen, and a metal solution, furnace slag and melt separation furnace gas are obtained. Melt separation treatment is conducted on direct reduction metal input by the gas-based shaft furnace through various gases input by the multi-tuyere side-blown melt separation furnace, carbon emission in the melt separation process is greatly reduced, shaft furnace gas is cooled and decarbonized to generate shaft furnace gas decarbonized gas, the shaft furnace gas decarbonized gas can be input into the multi-tuyere side-blown melt separation furnace to serve as fuel, and the energy consumption of the multi-tuyere side-blown melt separation furnace is reduced. Cyclic utilization of coal gas is achieved, and fuel is saved.

Description

Technical Field

[0001] This utility model relates to the field of low-carbon metal smelting technology, and in particular to a low-carbon metal smelting system powered by gas. Background Technology

[0002] In the process of low-carbon development in the steel industry, gas-based shaft furnace direct reduction technology has received widespread attention and application due to its ability to effectively reduce carbon emissions during metal reduction processes by not using solid carbon as a reducing agent. However, unlike traditional blast furnace processes, the direct reduced metal products produced by gas-based shaft furnaces are still solid, such as direct reduced iron (DRI), which requires further melting into a molten metal solution. Currently, the main methods for melting direct reduced metals are electric arc furnaces and coal-based molten reduction furnaces (coal and coking coal). Electric arc furnace processes are limited by power supply constraints, and in some steel companies, electricity is generated through gas-fired power generation, with the electric arc furnace then used to melt the direct reduced metals. Direct energy supply without gas leads to low energy utilization efficiency due to energy conversion issues. Furthermore, the amount of gas produced by electric arc furnaces is small, making it difficult to match the large amount of reducing gas required by gas-based shaft furnace processes. Coal-based molten reduction furnaces use solid carbon as fuel, resulting in high carbon emissions. If natural gas is used for energy supply while providing the same amount of heat, carbon emissions are approximately half that of coal.

[0003] Therefore, how to provide a smelting equipment with low carbon emissions, direct use of gas as energy, and high metal smelting efficiency is a technical problem that urgently needs to be solved. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, this application provides a low-carbon metal smelting system powered by natural gas to solve the above-mentioned technical problems.

[0005] To achieve the above and other related objectives, the technical solution provided in this application is as follows.

[0006] This application provides a low-carbon metal smelting system powered by gas, comprising a gas-based vertical shaft furnace for reducing ore to be reduced based on a reducing agent, a heat exchanger for cooling the furnace gas output from the gas-based vertical shaft furnace, a carbon capture device for decarbonizing the furnace gas output from the heat exchanger, and a multi-tuft side-blown smelting furnace for smelting the direct reduced metal output from the gas-based vertical shaft furnace; the first input end of the gas-based vertical shaft furnace serves as the input end of the ore to be reduced, the second input end of the gas-based vertical shaft furnace serves as the input end of the reducing agent, and the first output end of the gas-based vertical shaft furnace is connected to the heat exchanger. The input end of the heat exchanger is connected to the input end of the carbon capture device. The first input end of the multi-tuft side-blown smelting furnace is connected to the second output end of the gas-based vertical furnace. The multi-tuft side-blown smelting furnace includes a molten metal output end, a slag output end, and a smelting furnace gas output end. The smelting furnace gas output end is connected to the second input end of the gas-based vertical furnace. The second input end of the multi-tuft side-blown smelting furnace is connected to the first output end of the carbon capture device. The second input end of the multi-tuft side-blown smelting furnace includes multiple side-blown tufts, which serve as input ends for decarbonized gas, fuel gas, and oxygen from the vertical furnace.

[0007] Optionally, the output end of the smelting furnace gas is connected to the second input end of the gas-based vertical furnace through a pipeline, and a T-junction is also provided on the pipeline. The first input end of the T-junction is connected to the output end of the smelting furnace gas, the second input end of the T-junction serves as the input end of an external gas source, and the output end of the T-junction is connected to the second input end of the gas-based vertical furnace.

[0008] Optionally, the low-carbon metal smelting system further includes a dust removal device for removing dust from the vertical furnace gas. The input end of the dust removal device is connected to the first output end of the gas-based vertical furnace, and the output end of the dust removal device is connected to the input end of the heat exchange device.

[0009] Optionally, the multi-tuft side-blown smelting furnace has two sets of side-blown tufts arranged opposite each other on the four sides. Each set of side-blown tufts has three rows of side-blown tufts arranged from top to bottom. The first row of side-blown tufts serves as the input end of the oxygen, the second row of side-blown tufts serves as the input end of the decarbonized gas from the vertical furnace, the oxygen, and the fuel gas, and the third row of side-blown tufts serves as the input end of the oxygen and the fuel gas.

[0010] Optionally, the output end of the molten metal and the output end of the slag are provided on the adjacent sidewalls of the two sets of side air inlets. The first row of side air inlets is located above the output end of the slag. The height of the second row of side air inlets is located at and above the height of the output end of the slag, and the height of the second row of side air inlets is also located below the first row of side air inlets. The height of the third row of side air inlets is located at and above the output end of the molten metal, and the height of the third row of side air inlets is located below the second row of side air inlets.

[0011] Optionally, the top of the multi-tuft side-blown smelting furnace is offset to provide the first input end of the multi-tuft side-blown smelting furnace and the output end of the smelting furnace gas.

[0012] Optionally, the low-carbon metal smelting system further includes a gas transmission device for transmitting the vertical furnace gas output from the heat exchange device to other energy-consuming equipment, wherein the input end of the gas transmission device is connected to the output end of the heat exchange device.

[0013] Optionally, the low-carbon metal smelting system further includes a gas storage device for storing carbon dioxide output from the carbon capture device, wherein the input end of the gas storage device is connected to the second output end of the carbon capture device.

[0014] Optionally, the low-carbon metal smelting system further includes a heat transfer device for transferring the direct-reduced metal, wherein the input end of the heat transfer device is connected to the second output end of the gas-based vertical furnace, and the output end of the heat transfer device is connected to the first input end of the multi-tuyer side-blown melting furnace.

[0015] This application provides a gas-powered low-carbon metal smelting system, which includes a gas-based vertical shaft furnace, a heat exchange device, a carbon capture device, and a multi-tuft side-blown smelting furnace. The gas-based vertical shaft furnace reduces the ore to be reduced and the reducing agent input from two input ends to obtain direct reduced metal and shaft furnace gas. The shaft furnace gas is cooled and decarbonized sequentially through the heat exchange device and the carbon capture device to obtain decarbonized shaft furnace gas. The multi-tuft side-blown smelting furnace performs smelting and separation of the direct reduced metal based on the flux, and provides the energy required for the smelting and separation process through gas, decarbonized shaft furnace gas, and oxygen, thereby obtaining molten metal, slag, and smelting furnace gas. This application utilizes the gas input from the multi-tuyer side-blown smelting furnace to smelt and separate the direct reduction metal input from the gas-based vertical shaft furnace, significantly reducing carbon emissions during the smelting process. The vertical shaft furnace gas generated during the metal reduction process is converted into decarbonized vertical shaft furnace gas after passing through a heat exchange device and a carbon capture device. The decarbonized vertical shaft furnace gas can be input into the multi-tuyer side-blown smelting furnace as fuel, realizing the recycling of gas and saving fuel. Attached Figure Description

[0016] Figure 1This is a schematic diagram of a low-carbon metal smelting system powered by gas, illustrating an exemplary embodiment of the present invention.

[0017] Figure 2(a) is a top view of a multi-tuft side-blown melting furnace shown in an exemplary embodiment of the present invention;

[0018] Figure 2(b) is a front view of a multi-tuft side-blown melting furnace shown in an exemplary embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of a low-carbon metal smelting system powered by natural gas, as shown in an exemplary embodiment of this utility model.

[0020] Figure 4 This is a schematic diagram of a hydrogen-powered low-carbon metal smelting system, as shown in an exemplary embodiment of this utility model.

[0021] Attached reference numerals: 1-Gas-based vertical shaft furnace; 2-Dust removal device; 3-Heat exchange device; 4-Carbon capture device; 5-Multi-tuyer side-blown smelting furnace. Detailed Implementation

[0022] The embodiments of this utility model will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be understood that the preferred embodiments are only for illustrating this utility model and not for limiting the scope of protection of this utility model.

[0023] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0025] In the process of low-carbon development in the steel industry, gas-based shaft furnace direct reduction technology has received widespread attention and application due to its ability to effectively reduce carbon emissions during metal reduction processes by not using solid carbon as a reducing agent. However, unlike traditional blast furnace processes, the direct reduced metal products produced by gas-based shaft furnaces are still solid and require further melting into a molten metal solution. For example, direct reduced iron (DRI) needs to be melted into molten iron. Currently, the main melting methods for direct reduced metals are electric arc furnaces and coal-based molten reduction furnaces (coal and coking coal). Electric arc furnace processes are limited by power supply, and in some steel companies, electricity is generated through gas-fired power plants, which convert the gas into electricity to power the electric arc furnace for melting direct reduced metals. This melting process involves energy conversion, which results in energy loss and low energy utilization efficiency. Furthermore, the amount of gas produced by electric arc furnaces is small, making it difficult to match the large amount of reducing gas required by gas-based shaft furnace processes. Coal-based molten reduction furnaces use solid carbon as fuel, which has the problem of high carbon emissions during combustion. If the same amount of heat is provided, using natural gas for energy supply would result in carbon emissions of about half that of coal.

[0026] To address the aforementioned problems, this application provides a low-carbon metal smelting system powered by natural gas, comprising a gas-based shaft furnace for reducing the ore to be reduced using a reducing agent, a heat exchange device for cooling the furnace gas output from the gas-based shaft furnace, a carbon capture device for decarbonizing the furnace gas output from the heat exchange device, and a multi-tuyer side-blown smelting furnace for separating the direct reduced metal output from the gas-based shaft furnace; the first input end of the gas-based shaft furnace serves as the input end of the ore to be reduced, the second input end of the gas-based shaft furnace serves as the input end of the reducing agent, and the third input end of the gas-based shaft furnace... One output end is connected to the input end of the heat exchange device, and the output end of the heat exchange device is connected to the input end of the carbon capture device. The first input end of the multi-tuft side-blown smelting furnace is connected to the second output end of the gas-based vertical furnace. The multi-tuft side-blown smelting furnace includes a molten metal output end, a slag output end, and a smelting furnace gas output end. The smelting furnace gas output end is connected to the second input end of the gas-based vertical furnace. The second input end of the multi-tuft side-blown smelting furnace is connected to the first output end of the carbon capture device. The second input end of the multi-tuft side-blown smelting furnace includes multiple side-blown tufts, which serve as the input ends for the decarbonization gas, fuel gas, and oxygen of the vertical furnace.

[0027] like Figure 1As shown, the low-carbon metal smelting system powered by gas provided in this application includes a gas-based shaft furnace 1, which has a first input end and a second input end. The first input end of the gas-based shaft furnace 1 receives the ore to be reduced, and the second input end receives a reducing agent. The reducing agent reduces the ore to be reduced to obtain directly reduced metal and shaft furnace gas. A heat exchanger 3 is connected to the first output end of the gas-based shaft furnace 1, and the heat exchanger 3 cools the shaft furnace gas output from the gas-based shaft furnace 1. A carbon capture device 4 is connected to the heat exchanger 4. At the output end of the heat exchanger 3, the carbon capture device 4 decarbonizes the gas output from the heat exchanger 3 to obtain decarbonized vertical furnace gas and carbon dioxide; the multi-tuft side-blown smelting furnace 5 includes two input ends. The first input end of the multi-tuft side-blown smelting furnace inputs direct reducing metal and flux. Based on the decarbonized vertical furnace gas, fuel gas and oxygen input from multiple side-blown tufts in the second input end of the multi-tuft side-blown smelting furnace, energy is provided for the smelting process of direct reducing metal and flux. The multi-tuft side-blown smelting furnace 5 outputs molten metal, slag and smelting furnace gas.

[0028] Heat exchanger 3 reduces the temperature of the vertical furnace gas to below 40°C. The heat exchange method is one or more combinations of waste heat boiler and water spray cooling. Decarbonization device 4 removes CO2 from the vertical furnace gas output from the heat exchanger to below 1%. The removal method is one or more combinations of solution absorption, pressure swing adsorption, temperature swing adsorption, and membrane separation.

[0029] It should be noted that the gas-powered low-carbon metal smelting system provided in this application can be used to smelt metals such as iron, nickel, and cobalt, and is not limited to this application.

[0030] In detail, in an exemplary embodiment of this application, the output end of the smelting furnace gas is connected to the second input end of the gas-based vertical shaft furnace via a pipeline, and a tee connector is also provided on the pipeline. The first input end of the tee connector is connected to the output end of the smelting furnace gas, the second input end of the tee connector serves as the input end of an external gas source, and the output end of the tee connector is connected to the second input end of the gas-based vertical shaft furnace. Specifically, as shown... Figure 1 As shown, the output end of the smelting furnace gas is connected to the second input end of the gas-based vertical shaft furnace through a pipeline. The first input end of the tee connector on the pipeline inputs the smelting furnace gas, and the second input end of the tee connector serves as the input end of the external gas source. The smelting furnace gas output from the multi-tuyer side-blown smelting furnace is integrated with the external gas source through the tee connector, thereby increasing the gas temperature of the external gas source. No additional heating device is required, and reducing gas that meets the first preset temperature threshold range is obtained, which serves as the reducing agent for the gas-based vertical shaft furnace.

[0031] In detail, in an exemplary embodiment of this application, the low-carbon metal smelting system further includes a dust removal device 2 for removing dust from the vertical shaft furnace gas. The input end of the dust removal device 2 is connected to the first output end of the gas-based vertical shaft furnace 1, and the output end of the dust removal device 2 is connected to the input end of the heat exchange device 3. For example... Figure 1 As shown, a dust removal device 2 is installed between the gas-based vertical furnace 1 and the heat exchange device 3. The dust removal device 2 reduces the dust content in the vertical furnace gas to below 1 mg / Nm3. The dust removal method is one or more combinations of cyclone dust removal, wet dust removal, and electrostatic dust removal.

[0032] In detail, in an exemplary embodiment of this application, the multi-tuft side-blown smelting furnace 5 has two sets of side-blown tufts arranged opposite each other on the four sides. Each set of side-blown tufts has three rows of side-blown tufts arranged from top to bottom. The first row of side-blown tufts serves as the input end of oxygen, the second row of side-blown tufts serves as the input end of decarbonized gas, oxygen and fuel gas from the vertical furnace, and the third row of side-blown tufts serves as the input end of oxygen and fuel gas.

[0033] More specifically, in an exemplary embodiment of this application, an output end for molten metal and an output end for slag are provided on adjacent sidewalls of two sets of side air vents. The first row of side air vents is located above the output end of the slag. The height of the second row of side air vents is located at and above the height of the output end of the slag, and the height of the second row of side air vents is also located below the first row of side air vents. The height of the third row of side air vents is located at and above the output end of the molten metal, and the height of the third row of side air vents is located below the second row of side air vents.

[0034] Specifically, if the overall shape of the multi-tuft side-blown smelting furnace 5 is a cuboid, as shown in Figure 2(a), two sets of side-blown tufts are set on the two side walls around the multi-tuft side-blown smelting furnace 5. The two sets of side-blown tufts are positioned opposite each other, as shown in Figure 2(b). Each set of side-blown tufts includes three rows of side-blown tufts from top to bottom. Each row of side-blown tufts has multiple tufts. Slag and molten metal output ends are set on the side walls adjacent to the side-blown tufts. The molten metal output end is set below the slag output end, as shown in Figure 2(b). The first row of side-blown tufts is set above the slag output end. Because the slag is a relatively thick layer, the first row of side-blown tufts is set above the slag layer. Oxygen is input into the first row of side-blown tufts. The oxygen is pure oxygen. The pure oxygen is used to perform secondary combustion of the smelting furnace gas above the slag output end, thereby improving the combustion efficiency of the coal. The combustion rate of secondary combustion of gas; the height of the second row of side tuyeres is the same as or higher than the output port of the slag, and the height of the second row of side tuyeres is lower than the height of the first row of side tuyeres. The second row of side tuyeres inputs decarburized gas, fuel gas, and oxygen from the vertical furnace to heat the slag layer, allowing the direct reduction metal and flux to melt and react in the slag layer, producing molten metal and slag; the height of the third row of side tuyeres is the same as or higher than the output port of the molten metal, and the height of the third row of side tuyeres is lower than the height of the second row of side tuyeres. The third row of side tuyeres inputs fuel gas and oxygen, and the ratio of fuel gas and oxygen input into the third row of side tuyeres is adjusted to ensure that the molten metal does not oxidize, and reduction and carburization are achieved in excess fuel gas.

[0035] It should be emphasized that the shape of the multi-tuft side-blown melting furnace 5 is not limited to a cuboid, but can also be other geometric shapes.

[0036] More specifically, as shown in Figures 2(a) and 2(b), the top of the multi-tuft side-blown smelting furnace 5 is offset to set the first input end of the multi-tuft side-blown smelting furnace and the output end of the smelting furnace gas.

[0037] In detail, such as Figure 1 As shown, the low-carbon metal smelting system also includes a gas transmission device that transmits the vertical furnace gas output from the heat exchange device 3 to other energy-consuming equipment. The input end of the gas transmission device is connected to the output end of the heat exchange device 3.

[0038] More in detail, such as Figure 1 As shown, the low-carbon metal smelting system also includes a gas storage device for storing carbon dioxide output from the carbon capture device. The input end of the gas storage device is connected to the second output end of the carbon capture device 4 to convert and utilize high-purity CO2 or geologically seal it, so as to further reduce process carbon emissions.

[0039] In detail, the low-carbon metal smelting system also includes a heat transfer device for transferring direct reduced metal. The input end of the heat transfer device is connected to the second output end of the gas-based shaft furnace 1, and the output end of the heat transfer device is connected to the first input end of the multi-tuyer side-blown smelting furnace. Specifically, the direct reduced metal is transferred from the second output end of the gas-based shaft furnace to the first input end of the multi-tuyer side-blown smelting furnace via the heat transfer device, which can be a U-shaped trough.

[0040] like Figure 3-4 As shown, if the metal smelted by the low-carbon metal smelting system powered by gas is iron, the types of gas used in the smelting process include, but are not limited to, one or more combinations of natural gas, hydrogen, methane, decarbonized vertical furnace gas, and coke oven gas. External gas sources include, but are not limited to, natural gas and coke oven gas. Fluxes include, but are not limited to, lime, limestone, dolomite, and quartz.

[0041] Example 1

[0042] like Figure 3 As shown, taking a gas-based vertical shaft furnace with an annual output of 100,000 tons as an example, Table 1 shows the composition of the raw material pellets for the gas-based vertical shaft furnace.

[0043] Table 1. Composition of raw material pellets for a 100,000-ton / year gas-based vertical shaft furnace (mass fraction)

[0044]

[0045] In Table 1, Fe2O3, FeO, SiO2, Al2O3, CaO, MgO, MnO, TiO2 and other components are the composition of the pellets in the gas-based vertical shaft furnace, and TFe=68.29% is the total iron content of the pellets.

[0046] The pellets are reduced and carburized by reducing gas in a gas-based shaft furnace to obtain direct reduced iron (DRI) with the composition shown in Table 2.

[0047] Table 2. Composition of direct reduced iron (mass fraction) in products from a 100,000-ton / year gas-based vertical shaft furnace.

[0048]

[0049] In Table 2, MFe, FeO, SiO2, Al2O3, CaO, MgO, MnO, TiO2, C and other components are the composition of direct reduced iron, and TFe=93.74% is the total iron content in direct reduced iron.

[0050] Direct reduced iron is fed into the multi-tuyer side-blown melting furnace 5 via a heat transfer device with a feed temperature ≥600℃. At the same time, quicklime and dolomite are added as fluxes. The composition of quicklime and dolomite is shown in Table 3.

[0051] Table 3. Flux composition (mass fraction) of multi-tuyer side-blown melting furnace

[0052]

[0053] In Table 3, quicklime is composed of Fe2O3, SiO2, CaO, MgO, Al2O3 and other substances, while dolomite is composed of Fe2O3, SiO2, CaO, MgO, Al2O3 and other substances.

[0054] The multi-tuyer side-blown smelting furnace 5 uses natural gas, decarburized gas from the vertical shaft furnace, and oxygen for power. The third row of side-blown tuyeres injects a fuel-rich gas of natural gas and oxygen, while the second row injects a mixture of natural gas, decarburized gas from the vertical shaft furnace, and oxygen, with a molar ratio of 1:1. The first row of side-blown tuyeres injects oxygen, resulting in a secondary combustion rate of 40% for the furnace gas. One ton of molten iron consumes 77 kg of natural gas and decarburized gas, and 220 kg of oxygen. Compared to using coal as fuel, the carbon entering the side-blown smelting furnace is reduced by approximately 53%. The multi-tuyer side-blown smelting furnace 5 operates at a temperature of 1500℃~1600℃. On average, one ton of molten iron consumes 1095 kg of direct reduced iron, 21.7 kg of quicklime, and 2.4 kg of dolomite, with an iron recovery rate of 97%. The multi-tuyer side-blown smelting furnace produces 340 Nm3 of gas per 51 tons of iron at a temperature of 1500℃~1600℃. Reducing gas is produced by mixing natural gas with the high-temperature smelting furnace gas, fully utilizing the high-temperature sensible heat and chemical energy of the smelting furnace gas to obtain reducing gas at a temperature of 900℃~1000℃, which is then fed into a gas-based vertical shaft furnace as a reducing agent.

[0055] A reduction reaction occurs in the gas-based shaft furnace 1, producing direct reduced iron and shaft furnace gas. The outlet gas temperature is 200℃~400℃. The dust content of the shaft furnace gas is reduced to below 10mg / Nm3 by the dust removal device 2. The waste heat is recovered by the heat exchange device 3, and the temperature of the shaft furnace gas is reduced to below 40℃. The shaft furnace gas at a temperature below 40℃ is then passed through the carbon capture device 4 to remove CO2 to below 1%. The decarbonized shaft furnace gas is used as fuel gas for the side-blown smelting furnace.

[0056] Example 1: Natural gas was used to completely replace solid carbon for energy supply and reduction during the production of molten iron, significantly reducing carbon emissions in the ironmaking process; by setting up fuel-rich tuyeres in the iron layer of the side-blown furnace, the condensation of the iron layer and the reduction of FeO in the furnace charge were effectively prevented, thus improving the iron recovery rate; by coupling the gas from the side-blown smelting furnace with the gas-based vertical furnace, the utilization rate of the high-temperature sensible heat and chemical energy of the gas was improved.

[0057] Example 2

[0058] like Figure 4As shown, taking a gas-based vertical shaft furnace with an annual output of 50,000 tons as an example, Table 4 shows the composition of the raw material pellets for the gas-based vertical shaft furnace.

[0059] Table 4. Composition of raw material pellets for a 50,000-ton-per-year gas-based vertical shaft furnace (mass fraction)

[0060]

[0061] In Table 4, Fe2O3, FeO, SiO2, Al2O3, CaO, MgO, MnO, TiO2 and other components are the composition of the pellets in the gas-based vertical shaft furnace, and TFe=61.35% is the total iron content of the pellets.

[0062] The pellets are reduced and carburized by reducing gas in a gas-based shaft furnace to obtain direct reduced iron (DRI) with the composition shown in Table 5.

[0063] Table 5. Composition of direct reduced iron (mass fraction) in products from a 50,000-ton / year gas-based vertical shaft furnace.

[0064]

[0065] In Table 5, MFe, FeO, SiO2, Al2O3, CaO, MgO, MnO, TiO2, C and other components are the composition of direct reduced iron, and TFe=81.79% is the total iron content in direct reduced iron.

[0066] Direct reduced iron is fed into the multi-tuft side-blown melting furnace 5 via a heat transfer device with a feed temperature ≥600℃. At the same time, quicklime and dolomite are added as fluxes. The composition of quicklime and dolomite is the same as in Example 1, as shown in Table 3.

[0067] The multi-tuyer side-blown smelting furnace 5 uses hydrogen, decarburized vertical furnace gas, and oxygen for combustion. The third row of side-blown tuyeres injects a hydrogen- and oxygen-rich gas, while the second row injects a mixture of hydrogen, decarburized vertical furnace gas, and oxygen, with a molar ratio of 5:1. The first row of side-blown tuyeres injects oxygen, resulting in a secondary combustion rate of 40% for the smelting furnace gas. One ton of molten iron consumes 29.7 kg of hydrogen and 167.8 kg of oxygen, with an iron recovery rate of 96%. Compared to using solid carbon as fuel, using hydrogen produces no direct carbon emissions. The multi-tuyer side-blown smelting furnace 5 operates at a temperature of 1500℃~1600℃, consuming an average of 1225 kg of direct reduced iron, 67.4 kg of quicklime, and 5.8 kg of dolomite per ton of molten iron. The multi-tuyer side-blown smelting furnace produces 331 Nm3 of gas per 51 tons of iron at a temperature of 1500℃~1600℃. Reducing gas is produced by mixing natural gas with the high-temperature smelting furnace gas, fully utilizing the high-temperature sensible heat and chemical energy of the smelting furnace gas to obtain reducing gas at a temperature of 900℃~1000℃, which is then fed into a gas-based vertical shaft furnace as a reducing agent.

[0068] The process of the vertical furnace gas produced by gas-based vertical furnace 1 passing through dust removal device 2, heat exchange device 3, and carbon capture device 4 is the same, and will not be described again here.

[0069] In Example 2, hydrogen is used to completely replace solid carbon for energy supply and reduction during the production of molten iron, without directly generating carbon emissions. By setting up fuel-rich tuyeres in the iron layer of the side-blown furnace, the reduction of FeO in the furnace charge is effectively prevented by the iron layer solidification machine, thus improving the iron recovery rate.

[0070] The multi-vent side-blown smelting furnace (5) uses oxygen instead of air as a combustion aid to avoid the enrichment of N2 in the gas circulation system.

[0071] This application provides a gas-powered low-carbon metal smelting system, which includes a gas-based vertical shaft furnace, a heat exchange device, a carbon capture device, and a multi-tuft side-blown smelting furnace. The gas-based vertical shaft furnace reduces the ore to be reduced and the reducing agent input at two input ends to obtain direct reduced metal and shaft furnace gas. The shaft furnace gas is cooled and decarbonized sequentially through the heat exchange device and the carbon capture device to obtain decarbonized shaft furnace gas. The multi-tuft side-blown smelting furnace performs smelting and separation of the direct reduced metal based on flux. The multi-tuft side-blown smelting furnace inputs gas, decarbonized shaft furnace gas, and oxygen through multiple side-blown tufts to provide the energy required for the smelting and separation process, thereby obtaining molten metal, slag, and smelting furnace gas. This application utilizes a multi-tuft side-blown smelting furnace to process directly reduced metals fed into a gas-based vertical shaft furnace by layering gases from multiple tufts. This significantly reduces carbon emissions during the smelting process, enabling secondary combustion of the furnace gas and preventing oxidation of the molten metal. It also maintains the temperature of the multi-tuft smelting furnace from multiple perspectives. The furnace gas generated during the metal reduction process in the gas-based vertical shaft furnace is decarbonized after passing through a heat exchanger and a carbon capture device. This decarbonized gas can then be fed into the multi-tuft side-blown smelting furnace as fuel, achieving gas recycling and saving fuel.

[0072] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A low-carbon metal smelting system powered by a gas, characterized in that, The low-carbon metal smelting system comprises a gas-based shaft furnace for reducing a to-be-reduced ore material based on a reducing agent, a heat exchange device for cooling the shaft furnace gas output by the gas-based shaft furnace, a carbon capture device for decarburizing the shaft furnace gas output by the heat exchange device, and a multi-tuyere side-blown smelting furnace for smelting the direct-reduced metal output by the gas-based shaft furnace; the first input end of the gas-based shaft furnace is used as the input end of the to-be-reduced ore material, the second input end of the gas-based shaft furnace is used as the input end of the reducing agent, the first output end of the gas-based shaft furnace is connected with the input end of the heat exchange device, the output end of the heat exchange device is connected with the input end of the carbon capture device, the first input end of the multi-tuyere side-blown smelting furnace is connected with the second output end of the gas-based shaft furnace, the multi-tuyere side-blown smelting furnace comprises a metal solution output end, a slag output end and a smelting furnace gas output end, the smelting furnace gas output end is connected with the second input end of the gas-based shaft furnace, the second input end of the multi-tuyere side-blown smelting furnace is connected with the first output end of the carbon capture device, and the second input end of the multi-tuyere side-blown smelting furnace comprises a plurality of side-blown tuyeres, which are used as the input ends of the shaft furnace gas decarburization gas, the fuel gas and the oxygen.

2. The gas energized low carbon metal smelting system of claim 1, wherein, The output end of the smelting furnace gas is connected with the second input end of the gas-based shaft furnace through a pipeline, and a three-way joint is further arranged on the pipeline, the first input end of the three-way joint is connected with the output end of the smelting furnace gas, the second input end of the three-way joint is used as the input end of an external gas source, and the output end of the three-way joint is connected with the second input end of the gas-based shaft furnace.

3. The gas energized low carbon metal smelting system of claim 1, wherein, The low-carbon metal smelting system further comprises a dust removal device for dust removal of the shaft furnace gas, the input end of the dust removal device is connected with the first output end of the gas-based shaft furnace, and the output end of the dust removal device is connected with the input end of the heat exchange device.

4. The gas-fired, low-carbon metal smelting system of any of claims 1-3, wherein, The multi-tuyere side-blown smelting furnace oppositely arranges two groups of side-blown tuyeres on the circumferential side walls, each group of side-blown tuyeres is arranged with three rows of side-blown tuyeres from top to bottom, the first row of side-blown tuyeres is used as the input end of the oxygen, the second row of side-blown tuyeres is used as the input end of the shaft furnace gas decarburization gas, the oxygen and the fuel gas, and the third row of side-blown tuyeres is used as the input end of the oxygen and the fuel gas.

5. The gas energized low carbon metal smelting system of claim 4, wherein, The output end of the metal solution and the output end of the slag are arranged on the adjacent side walls of the two groups of side-blown tuyeres, the first row of side-blown tuyeres is arranged above the output end of the slag, the height of the second row of side-blown tuyeres is located above the height of the output end of the slag, and the height of the second row of side-blown tuyeres is also located below the first row of side-blown tuyeres; the height of the third row of side-blown tuyeres is located above the output end of the metal solution, and the height of the third row of side-blown tuyeres is located below the second row of side-blown tuyeres.

6. The gas energized low carbon metal smelting system of claim 4, wherein, The first input end of the multi-tuyere side-blown smelting furnace and the output end of the smelting furnace gas are arranged in a staggered manner on the top of the multi-tuyere side-blown smelting furnace.

7. The gas energized low carbon metal smelting system of claim 1, wherein, The low-carbon metal smelting system further comprises a gas transmission device for transmitting the shaft furnace gas output by the heat exchange device to other energy-consuming equipment, and the input end of the gas transmission device is connected with the output end of the heat exchange device.

8. The gas energized low carbon metal smelting system of claim 1, wherein, The low-carbon metal smelting system further comprises a gas storage device for storing the carbon dioxide output by the carbon capture device, an input end of the gas storage device being connected to the second output end of the carbon capture device.

9. The gas energized low carbon metal smelting system of claim 1, wherein, The low-carbon metal smelting system further comprises a heat transfer device for transferring the direct reduced metal, an input end of the heat transfer device being connected to the second output end of the gas-based shaft furnace, and an output end of the heat transfer device being connected to the first input end of the multi-tuyere side-blown smelting and separating furnace.

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