A steel smelting system and method based on hydrogen-rich reducing gas injection

Abstract

The invention discloses a steel smelting system and method based on hydrogen-rich reducing gas injection, comprising a blast furnace and a hydrogen-rich reducing gas prefabrication furnace; hydrogen-rich reducing gas and pure hydrogen from the hydrogen-rich reducing gas prefabrication furnace are injected into the blast furnace; the generated blast furnace top gas is introduced into the hydrogen-rich reducing gas prefabrication furnace for decarbonization; the hydrogen-rich reducing gas prefabrication furnace includes coke, biomass particles and waste plastic particles, and dry coal powder and pure oxygen are also injected into the hydrogen-rich reducing gas prefabrication furnace to prepare hydrogen-rich reducing gas.

Description

Technical Field

[0001] The invention relates to steel smelting, and in particular to a steel smelting system and method based on hydrogen-rich reducing gas injection. Background Art

[0002] At present, the main fuel, skeleton and reducing agent for smelting hot metal in blast furnaces is coke. Coke is obtained by dry distillation of coal at a high temperature of about 1000℃ in coking plants. The coking process produces a large amount of harmful chemical pollutants, and its cost is high. In order to ensure the air permeability of the blast furnace, the coke fragments and coke cubes produced in the coking process generally cannot be directly introduced into the blast furnace.

[0003] Reducing the coke ratio of blast furnaces is the key to blast furnace energy conservation. In traditional blast furnace smelting, low-coal powder is mainly injected into the blast furnace to partially replace coke. However, large-scale coal injection will bring a series of adverse effects to blast furnace smelting. For example, coal powder will undergo a series of physical and chemical changes such as heating, decomposition, combustion, and slagging inside the blast furnace, making the reaction in the cyclotron zone complicated and difficult to operate; with the increase in the amount of coal injection, the soft melting zone expands, and the coke is severely damaged, resulting in the coal injection being restricted by the quality of coke; the increase in unburned coal powder will further deteriorate the working conditions of the blast furnace soft melting zone and slag zone; and large-scale oxygen-rich coal injection will also cause the blast furnace to be "cold on top and hot on the bottom".

[0004] In addition, blast furnace smelting produces blast furnace top gas. Blast furnace gas contains CO and CO2. In order to recover CO in blast furnace gas, blast furnace gas will be re-injected back into the blast furnace. Before that, CO2 needs to be removed from blast furnace gas, which is also a problem.

[0005] Hydrogen has the advantages of being green, renewable, highly reducible, clean and pollution-free. Hydrogen is used extensively to replace carbon as a fuel and reducing agent in metallurgical processes, and the reaction product is water. Compared with traditional carbon metallurgy, it can fundamentally reduce carbon emissions and achieve the goal of clean production.

[0006] Compared with coal, the H2 / CO ratio in the gasification products of waste plastics is much larger than that when pulverized coal is injected, which is more conducive to the high-temperature reduction of iron oxides. However, the direct injection of plastics into blast furnaces is still in the research stage.

[0007] Another clean and renewable energy source, biomass pellets, has a high calorific value and the characteristics of "carbon cycle and carbon neutrality". When injected into the blast furnace, it can not only make up for the heat loss in the lower part of the blast furnace caused by hydrogen, but also save coal resources, reduce the possibility of unburned coal powder affecting the air permeability of the blast furnace, and will not produce excess carbon emissions. However, the existing traditional tuyere cannot achieve mixed injection of gas and biomass pellets. Summary of the invention

[0008] In view of the above-mentioned defects of the prior art, the present invention provides a steel smelting system based on hydrogen-rich reducing gas injection, comprising a blast furnace and a hydrogen-rich reducing gas prefabrication furnace; hydrogen-rich reducing gas and pure hydrogen from the hydrogen-rich reducing gas prefabrication furnace are injected into the blast furnace; the generated blast furnace top gas is circulated into the hydrogen-rich reducing gas prefabrication furnace for decarbonization; the material column in the hydrogen-rich reducing gas prefabrication furnace includes coke, biomass particles and waste plastic particles, and dry coal powder and pure oxygen are also injected into the hydrogen-rich reducing gas prefabrication furnace to prepare hydrogen-rich reducing gas.

[0009] Furthermore, the blast furnace includes an iron-making blast furnace, a pig iron casting blast furnace, and a ferroalloy blast furnace.

[0010] Furthermore, the dry coal powder is hydrogen-rich coal powder.

[0011] Furthermore, pure hydrogen is green electricity produced through blast furnace, converter gas power generation, photovoltaic, wind, nuclear, hydropower and grid valley electricity, produced by water electrolysis, or produced by reforming and purifying hydrogen-rich gases such as coke oven gas and natural gas.

[0012] Furthermore, the molten iron produced in the blast furnace is supplied to primary steelmaking furnaces including converters and electric arc furnaces to produce carbon structural steel, alloy structural steel, low-alloy high-strength structural steel, carbon tool steel, alloy tool steel, high-speed tool steel, high-carbon steel castings, high-carbon iron castings and stainless steel, as well as special-purpose steels with the addition of specific alloy elements including rare earths; the special-purpose steels include marine corrosion-resistant steel; and profiles, plates, pipes, bars and wires rolled from the above-mentioned steels.

[0013] Furthermore, a double-cylinder spiral distributor is used at the feed inlet of the hydrogen-rich reducing gas prefabrication furnace, including an outer cylinder; the upper part of the outer cylinder is a spiral material channel, and the lower part is an inner cylinder; the inner cylinder extends downward from under the outer cylinder, and the length of the inner cylinder is set so that its outlet can be immersed in the material column in the hydrogen-rich reducing gas prefabrication furnace, and a plurality of pressure equalizing holes are provided in the part where the inner cylinder extends beyond the outer cylinder to balance the pressure in the inner cylinder and the furnace.

[0014] The present invention also provides a steel smelting method based on hydrogen-rich reducing gas injection, comprising the steps of:

[0015] (1) Adding chopped coke, biomass particles and waste plastic particles into a hydrogen-rich reducing gas pre-production furnace, and simultaneously spraying dry coal powder and pure oxygen into the furnace to burn and prepare hydrogen-rich reducing gas;

[0016] (2) mixing the hydrogen-rich reducing gas from the hydrogen-rich reducing gas prefabrication furnace with pure hydrogen and spraying the mixture into the blast furnace;

[0017] (3) introducing the generated blast furnace top gas into a hydrogen-rich reducing gas prefabrication furnace for decarbonization;

[0018] (4) simultaneously injecting pure oxygen into the blast furnace;

[0019] (5) The molten iron produced in the blast furnace is supplied to primary steelmaking furnaces including converters and electric arc furnaces for the production of carbon structural steel, alloy structural steel, low alloy high strength structural steel, carbon tool steel, alloy tool steel, high speed tool steel, high carbon steel castings, high carbon iron castings and stainless steel.

[0020] Furthermore, the dry coal powder is hydrogen-rich coal powder.

[0021] Furthermore, pure hydrogen is green electricity produced through blast furnace, converter gas power generation, photovoltaic, wind, nuclear, hydropower and grid valley electricity, produced by water electrolysis, or produced by reforming and purifying hydrogen-rich gases such as coke oven gas and natural gas.

[0022] Furthermore, a double-cylinder spiral distributor is used at the inlet of the hydrogen-rich reducing gas prefabrication furnace, including an outer cylinder; the upper part of the outer cylinder is a spiral material channel, and the lower part is an inner cylinder; the inner cylinder extends downward from below the outer cylinder, and the length of the inner cylinder is set so that the outlet is immersed in the material column in the hydrogen-rich reducing gas prefabrication furnace, and at the same time, a plurality of pressure equalizing holes are set in the part where the inner cylinder extends beyond the outer cylinder to balance the pressure in the inner cylinder and the furnace; the mixture of charred diced, biomass particles and waste plastic particles enters the spiral material channel from above, and in the process of falling along the spiral material channel, due to the large density of charred diced, its movement trajectory is closer to the outer cylinder under the action of inertia, while the biomass particles and waste plastic particles have small densities and their movement trajectories are closer to the inner cylinder; in this way, after passing through the spiral material channel, most of the charred diced enters the furnace through the shorter outer cylinder and participates in the reaction in the furnace earlier, while most of the biomass particles and waste plastic particles enter the furnace through the longer inner cylinder and participate in the reaction in the furnace later.

[0023] The present invention adopts a hydrogen-rich reducing gas prefabrication furnace, which can prefabricate resources such as coal powder, coke, biomass particles and waste plastic particles that are not suitable for direct entry into the blast furnace but are beneficial to reducing the energy consumption of the blast furnace into hydrogen-rich reducing gas, and then can be sprayed into the blast furnace together with hydrogen. Among them, prefabricating coal powder into hydrogen-rich reducing gas can eliminate the adverse effects of coal injection on the blast furnace condition; prefabricating coke, biomass particles and waste plastic particles into hydrogen-rich reducing gas can make the resources fully utilized and recycled. Introducing blast furnace gas into the hydrogen-rich reducing gas prefabrication furnace can conveniently achieve decarbonization of blast furnace gas. More importantly, the comprehensive treatment of the above-mentioned various resources by the hydrogen-rich reducing gas prefabrication furnace is uniformly converted into hydrogen-rich reducing gas, which can be realized when mixed with pure hydrogen in the subsequent injection, and the ratio of CO and H2 can be dynamically adjusted by the control system according to the changes in the components in the hydrogen-rich reducing gas, thereby realizing the control of the blast furnace reducing atmosphere and heat, so that the furnace ore can be replaced and controlled. In summary, by uniformly recycling, converting and utilizing resources, the present invention reduces the energy consumption of blast furnaces, thereby reducing carbon emissions from steelmaking. The present invention also provides a double-barrel spiral distributor, which can make the consumption rates of faster-burning biomass particles and waste plastic particles and slower-burning coke diced similar. In this way, during the prefabrication of hydrogen-rich reducing gas, the raw material distribution of the furnace column can be more uniform, and the temperature in the furnace can be more balanced.

[0024] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a steel smelting system based on hydrogen-rich reducing gas injection in a preferred embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of a hydrogen-rich reducing gas prefabrication furnace in a preferred embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of a double-tube spiral distributor in a preferred embodiment of the present invention;

[0028] Figure 4 It is used Figure 3 Schematic diagram of the hydrogen-rich reducing gas prefabrication furnace with a double-drum spiral distributor. DETAILED DESCRIPTION

[0029] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0030] A steelmaking system based on hydrogen-rich reducing gas injection in a preferred embodiment of the present invention is as follows Figure 1 As shown, it includes a blast furnace 2 and a hydrogen-rich reducing gas prefabrication furnace 1. The hydrogen-rich reducing gas from the hydrogen-rich reducing gas prefabrication furnace 1, the hydrogen obtained by green electricity electrolysis and pure oxygen are sprayed into the blast furnace 2 to smelt molten iron. Then the molten iron produced by the blast furnace 2 enters the steelmaking process and is supplied to the primary steelmaking furnaces such as converters and electric arc furnaces to produce carbon structural steel, alloy structural steel, low alloy high-strength structural steel, carbon tool steel, alloy tool steel, high-speed tool steel, high-carbon steel castings, high-carbon iron castings and stainless steel.

[0031] In order to preform hydrogen-rich reducing gas, coke, biomass particles and waste plastic particles are added from the top of the hydrogen-rich reducing gas preformation furnace 1, dry coal powder and industrial pure oxygen are sprayed from the furnace body of the hydrogen-rich reducing gas preformation furnace 1, and blast furnace gas from the blast furnace 2 is also introduced into the hydrogen-rich reducing gas preformation furnace 2. The dry coal powder is preferably hydrogen-rich coal powder.

[0032] In a preferred embodiment of the present invention, the hydrogen-rich reducing gas prefabrication furnace 1 is as follows Figure 2 As shown, the lower part of the furnace body is ash 13, and the middle part is coke 11 and biomass particles, waste plastic particles 12, and coal powder and industrial pure oxygen are sprayed in at the same time to burn and generate hydrogen-rich reducing gases such as CO and H2, which are discharged from the upper part of the furnace body of the hydrogen-rich reducing gas prefabrication furnace 1 and blown into the blast furnace 2.

[0033] The CO2 in the blast furnace gas introduced into the hydrogen-rich reducing gas prefabrication furnace 1 reacts with the coke in the furnace and is reduced to CO.

[0034] The present invention adopts a hydrogen-rich reducing gas prefabrication furnace, which can prefabricate resources such as coal powder, coke, biomass particles and waste plastic particles that are not suitable for direct entry into the blast furnace but are beneficial to reducing the energy consumption of the blast furnace into hydrogen-rich reducing gas, and then can be sprayed into the blast furnace together with hydrogen. Among them, prefabricating coal powder into hydrogen-rich reducing gas can eliminate the adverse effects of coal injection on the blast furnace condition; prefabricating coke, biomass particles and waste plastic particles into hydrogen-rich reducing gas can make the resources fully utilized and recycled. Introducing blast furnace gas into the hydrogen-rich reducing gas prefabrication furnace can conveniently achieve decarbonization of blast furnace gas. More importantly, the comprehensive treatment of the above-mentioned various resources by the hydrogen-rich reducing gas prefabrication furnace is uniformly converted into hydrogen-rich reducing gas, which can be realized when mixed with pure hydrogen in the subsequent injection, and the ratio of CO and H2 can be dynamically adjusted by the control system according to the changes in the components in the hydrogen-rich reducing gas, thereby realizing the control of the blast furnace reducing atmosphere and heat, so that the furnace ore can be replaced and controlled.

[0035] Compared with chopped coke, biomass particles and waste plastic particles have a lower density and burn faster. If the three are evenly distributed, it is easy to cause chopped coke to gather in the material column in the hydrogen-rich reducing gas prefabrication furnace, resulting in uneven temperature in the furnace, causing furnace condition fluctuations and even safety accidents. Figure 3 and 4 In the further embodiment shown, a double-barrel spiral distributor is used at the feed port of the hydrogen-rich reducing gas prefabrication furnace 1, including an outer barrel 2. The upper part of the outer barrel 2 is a spiral material channel 3, and the lower part is an inner barrel 4. The inner barrel 4 extends downward from below the outer barrel 2, and its length makes its outlet immersed in the material column in the hydrogen-rich reducing gas prefabrication furnace. A plurality of pressure equalizing holes 5 are provided in the portion where the inner barrel 4 extends beyond the outer barrel 2 to balance the pressure in the inner barrel 4 and the furnace to avoid poor material discharge. The mixture of coke diced, biomass particles and waste plastic particles in the inner barrel 4 enters the spiral material channel 3 from above. In the process of falling along the spiral material channel, due to the large density of coke diced, its movement trajectory is closer to the outer barrel under the action of inertia, while the biomass particles and waste plastic particles have small densities and their movement trajectories are closer to the inner barrel. In this way, after passing through the spiral material channel, most of the coke will enter the furnace through the shorter outer cylinder and participate in the furnace reaction earlier, while most of the biomass particles and waste plastic particles will enter the furnace through the longer inner cylinder, and the outlet of the inner cylinder is immersed in the material column. Following the consumption of the material column, they naturally descend into the material column, so they will participate in the furnace reaction later. In this way, although they enter the furnace at the same time, due to the different starting time of participating in the reaction, the consumption rate of the faster burning biomass particles and waste plastic particles and the slower burning coke can be similar. In this way, during the prefabrication of hydrogen-rich reducing gas, the raw material distribution of the furnace column can be more uniform, and the temperature in the furnace can be more balanced.

[0036] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A steel smelting system based on hydrogen-rich reducing gas injection, characterized in that: It comprises a blast furnace and a hydrogen-rich reducing gas prefabrication furnace; pure hydrogen and hydrogen-rich reducing gas from the hydrogen-rich reducing gas prefabrication furnace are sprayed into the blast furnace; the generated blast furnace top gas is circulated into the hydrogen-rich reducing gas prefabrication furnace for decarbonization; the material column in the hydrogen-rich reducing gas prefabrication furnace comprises coke, biomass particles and waste plastic particles, and dry coal powder and pure oxygen are also sprayed into the hydrogen-rich reducing gas prefabrication furnace to prepare hydrogen-rich reducing gas; a double-cylinder spiral distributor is adopted at the material inlet of the hydrogen-rich reducing gas prefabrication furnace, comprising an outer cylinder; the upper part of the outer cylinder is a spiral material channel, and the lower part is an inner cylinder; the inner cylinder extends downwardly from under the outer cylinder, and the length of the inner cylinder is set so that its outlet is immersed in the material column in the hydrogen-rich reducing gas prefabrication furnace, and a plurality of pressure equalizing holes are set at the part of the inner cylinder extending beyond the outer cylinder to balance the pressure in the inner cylinder and the furnace.

2. The steel smelting system based on hydrogen-rich reducing gas injection according to claim 1, wherein: Blast furnaces include iron-making blast furnaces, blast furnaces for casting pig iron, and blast furnaces for ferroalloys.

3. The steel smelting system based on hydrogen-rich reducing gas injection according to claim 1, wherein: The dry pulverized coal is hydrogen-rich pulverized coal.

4. The steel smelting system based on hydrogen-rich reducing gas injection according to claim 1, wherein: Pure hydrogen is green electricity produced through blast furnace, converter gas power generation, photovoltaic, wind, nuclear, hydropower and grid valley electricity, and is produced by electrolysis of water; or it is produced by reforming and purifying coke oven gas and natural gas.

5. The steel smelting system based on hydrogen-rich reducing gas injection according to claim 1, wherein: The molten iron produced in the blast furnace is supplied to primary steelmaking furnaces including converters and electric arc furnaces to produce carbon structural steel, alloy structural steel, low-alloy high-strength structural steel, carbon tool steel, alloy tool steel, high-speed tool steel, high-carbon steel castings, high-carbon iron castings and stainless steel, as well as special-purpose steels with specific alloy elements including rare earths; the special-purpose steels include marine corrosion-resistant steel; and profiles, plates, pipes, bars and wires rolled from the above-mentioned steels.

6. A smelting method using a steel smelting system based on hydrogen-rich reducing gas injection as described in any one of claims 1 to 5, characterized in that: Includes steps: (1) Adding chopped coke, biomass particles and waste plastic particles into a hydrogen-rich reducing gas pre-production furnace, and simultaneously spraying dry coal powder and pure oxygen into the furnace to burn and prepare hydrogen-rich reducing gas; (2) mixing pure hydrogen with the hydrogen-rich reducing gas from the hydrogen-rich reducing gas prefabrication furnace and spraying the mixture into the blast furnace; (3) introducing the generated blast furnace top gas into a hydrogen-rich reducing gas prefabrication furnace for decarbonization; (4) simultaneously injecting pure oxygen into the blast furnace; (5) Supplying the molten iron produced in the blast furnace to primary steelmaking furnaces including converters and electric arc furnaces for the production of carbon structural steel, alloy structural steel, low alloy high strength structural steel, carbon tool steel, alloy tool steel, high speed tool steel, high carbon steel castings, high carbon iron castings and stainless steel; A double-barrel spiral distributor is used at the inlet of the hydrogen-rich reducing gas prefabrication furnace, including an outer barrel; the upper part of the outer barrel is a spiral material channel, and the lower part is an inner barrel; the inner barrel extends downward from below the outer barrel, and the length of the inner barrel is set so that its outlet is immersed in the material column in the hydrogen-rich reducing gas prefabrication furnace, and at the same time, a plurality of pressure equalizing holes are set in the part where the inner barrel extends beyond the outer barrel to balance the pressure in the inner barrel and the furnace; the mixture of chopped coke, biomass particles and waste plastic particles enters the spiral material channel from above, and in the process of falling along the spiral material channel, due to the large density of chopped coke, its movement trajectory is closer to the outer barrel under the action of inertia, while the biomass particles and waste plastic particles have small densities and their movement trajectories are closer to the inner barrel; in this way, after passing through the spiral material channel, most of the chopped coke enters the furnace through the shorter outer barrel and participates in the reaction in the furnace earlier, while most of the biomass particles and waste plastic particles enter the furnace through the longer inner barrel and participate in the reaction in the furnace later.

7. The iron and steel smelting method based on hydrogen-rich reducing gas injection according to claim 6, wherein: The dry pulverized coal is hydrogen-rich pulverized coal.

8. The steelmaking method based on hydrogen-rich reducing gas injection according to claim 6, wherein: Pure hydrogen is green electricity produced through blast furnace, converter gas power generation, photovoltaic, wind, nuclear, hydropower and grid valley electricity, and is produced by electrolysis of water; or it is produced by reforming and purifying coke oven gas and natural gas.

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