Green low-carbon blast furnace ironmaking system and smelting process
By pre-reducing and purifying iron-containing materials through a pre-reducer and carbon recycling route, the problems of coke consumption and carbon dioxide emissions in blast furnace ironmaking are solved, achieving efficient, energy-saving, green, and low-carbon ironmaking.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-10
AI Technical Summary
During the blast furnace ironmaking process, the calorific value of blast furnace gas is low and the nitrogen content is high, resulting in poor reducing ability, high coke consumption, high carbon dioxide emissions, and increased production costs.
A pre-reducer is used to pre-reduce iron-containing materials. Combined with indirect and direct reduction zones, the reducing gas is purified and recycled. A circulation route for carbon monoxide and carbon dioxide is set up. Hydrogen is produced using an electrolysis water device for carbon recycling and decarbonization.
It reduced coke consumption, decreased carbon dioxide emissions, improved smelting efficiency, and achieved green and low-carbon blast furnace ironmaking.
Smart Images
Figure CN121826259A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of blast furnace smelting technology, specifically relating to a green and low-carbon blast furnace ironmaking system and smelting process. Background Technology
[0002] Due to its excellent technical and economic indicators, simple process, large production capacity, and high labor productivity, blast furnace ironmaking accounts for over 95% of the world's total iron production. In the blast furnace ironmaking process, iron ore, coke, limestone, and other slag-forming solvents are charged from the top of the furnace. Preheated hot air is blown in from the tuyeres located at the bottom of the furnace along its perimeter. At high temperatures, the carbon and hydrocarbons in the coke react with the oxygen in the blown hot air to produce reducing gases such as carbon monoxide and hydrogen. As these reducing gases rise within the furnace, they remove oxygen from the iron ore, thus reducing it to iron. The molten iron is discharged from the taphole. Unreduced impurities in the iron ore combine with the limestone and other solvents to form slag, which is discharged from the slag outlet. The generated gas is extracted from the top of the furnace, purified by dust removal, and used as fuel for hot blast stoves, coke ovens, boilers, etc.
[0003] Currently, in blast furnace ironmaking, the use of air in the process results in blast furnace gas containing a large amount of nitrogen. This leads to a low calorific value and poor reducing ability of the gas, making it unsuitable for decarbonization and recycling. Consequently, it is emitted, causing significant carbon dioxide emissions. Secondly, during production, the direct reduction rate in the furnace is as high as 30-40%, while the indirect reduction rate is only 60-70%. Indirect reduction is an exothermic reaction that consumes almost no additional heat, while direct reduction is a strongly endothermic reaction that requires a large amount of heat. The increased direct reduction rate means that more coke needs to be burned in the lower part of the blast furnace to provide the additional heat required for the reaction, leading to an increase in the amount of coke and fuel consumed per ton of iron, and a sharp increase in production costs. Therefore, it is objectively necessary to develop a green, low-carbon blast furnace ironmaking system and smelting process that can achieve decarbonization and recycling of blast furnace gas, resulting in less environmental pollution and energy savings. Summary of the Invention
[0004] In order to solve the problems existing in the background technology, the purpose of this invention is to provide a green and low-carbon blast furnace ironmaking system and smelting process that can realize the decarbonization and recycling of blast furnace gas, with less environmental pollution and energy saving.
[0005] The green and low-carbon blast furnace ironmaking system of this invention includes a blast furnace and a direct reduction zone and an indirect reduction zone located within the blast furnace. A gas purifier, a separator, and a burner are sequentially connected to the blast furnace's outlet. The separated gas outlet of the separator is connected to a carbon dioxide storage tank. A heat exchange tube is installed inside the burner. The outlet of the separator is connected to the inlet of the heat exchange tube, and the outlet of the heat exchange tube is connected to the lower part of the indirect reduction zone. An oxygen storage tank, an electrolysis water device, a reactor, and a pre-reducer are installed outside the blast furnace. The oxygen storage tank is connected to the lower part of the direct reduction zone via a pipeline. The outlet of the gas purifier is connected to the burner via a pipeline. The outlets of the burner, the electrolysis water device, and the carbon dioxide storage tank are all connected to the inlet of the reactor via pipelines. The outlet of the reactor is connected to the lower part of the pre-reducer. The bottom of the pre-reducer is connected to the top of the blast furnace. The outlet of the pre-reducer is connected to the blast furnace's outlet. The electrolysis water device is connected to the inlet of the heat exchange tube.
[0006] Furthermore, the gas purifier includes a cyclone separator, a dehumidifier, and a bag filter connected in sequence.
[0007] Furthermore, a heat exchanger is installed on the pipeline between the gas purifier and the separator. The outlet of the oxygen storage tank is connected to the cold medium inlet of the heat exchanger, and the cold medium outlet of the heat exchanger is connected to the lower part of the direct reduction zone.
[0008] Furthermore, the cold medium outlet of the heat exchanger is connected to the burner via a branch pipe.
[0009] Furthermore, an oxygen removal catalyst is installed inside the reactor.
[0010] Furthermore, a gas mixer is installed at the gas inlet of the reactor, and the gas outlets of the burner, the water electrolysis device, and the carbon dioxide storage tank are all connected to the gas mixer via pipelines.
[0011] The smelting process of the green and low-carbon blast furnace ironmaking system described in this invention includes the following steps: ① Pre-reduction reaction: After mixing the iron-containing material with coke, add it in batches from the top. At the same time, high-temperature reducing gases carbon monoxide and hydrogen are introduced from the bottom of the pre-reducer. They come into countercurrent contact with the downward-moving iron-containing material and a gas-solid phase reaction occurs, which removes oxygen from the iron-containing material and carries out a pre-reduction reaction on the iron-containing material. ② Blast furnace ironmaking: The iron-containing materials and coke after the reaction in step ① are added to the blast furnace from the top. Reducing gases carbon monoxide and hydrogen are introduced into the indirect reduction zone of the blast furnace, and oxygen is introduced into the direct reduction zone of the blast furnace. The coke is burned, generating carbon monoxide and releasing a large amount of heat. The liquid iron oxide that has not been completely reduced by indirect means comes into direct contact with the hot coke. The iron-containing materials are reduced to obtain molten iron. ③ Carbon monoxide recycling: The coal gas generated during the smelting process in steps ① and ② is passed from the pre-reducer and the coal gas outlet at the top of the blast furnace into a gas purifier to remove residues, dust, and moisture from the coal gas. The purified coal gas is then passed into a separator to remove carbon dioxide, forming a reducing gas with carbon monoxide and hydrogen as the main components. At the same time, hydrogen is produced using an electrolysis water device. The hydrogen is mixed into the reducing gas to produce a hydrogen-rich mixed reducing gas, which is then passed into the heat exchange tubes in the burner. Meanwhile, a portion of the purified coal gas is separated through pipelines and fed into the burner for combustion, generating high temperatures to heat the hydrogen-rich mixed reducing gas in the heat exchange tubes. The heated hydrogen-rich mixed reducing gas is then returned to the indirect reduction zone of the blast furnace, thus realizing the recycling of carbon monoxide. ④ Carbon dioxide recycling: In step ③, the coal gas is burned in the burner to produce high-temperature carbon dioxide. The separator separates the carbon dioxide from the coal gas. This carbon dioxide, along with some of the hydrogen produced by the water electrolysis device, is fed into the reactor. Using metal oxide as a catalyst, carbon dioxide and hydrogen react in the reactor to produce carbon monoxide. Carbon monoxide and unreacted hydrogen are fed into the pre-reducer as reducing gases to achieve the recycling of carbon dioxide. ⑤ Slag discharge: Molten iron and slag generated in the blast furnace are discharged from the tapping hole and slag discharge hole.
[0012] Furthermore, in step ③, the hydrogen-rich mixed reducing gas contains 60% to 90% hydrogen and 10% to 40% carbon monoxide.
[0013] Furthermore, in step ④, the metal oxide is a copper-based catalyst or an iron-based catalyst.
[0014] The beneficial effects of this invention are as follows: I. This invention incorporates a pre-reducer to pre-reduce iron-containing materials, ensuring that the materials undergo a certain degree of reduction before entering the blast furnace. At this point, the metallization rate of the iron-containing materials reaches 40%–50%. Subsequently, the materials are added to the blast furnace for deep reduction, undergoing another indirect reduction reaction in the indirect reduction zone of the blast furnace, resulting in a metallization rate of 85%–95%. Finally, a direct reduction reaction is carried out in the direct reduction zone of the blast furnace. This significantly reduces the amount of iron-containing materials that need to be processed by direct reduction, reduces the heat required for direct reduction of iron-containing materials, and reduces the amount of coke and fuel consumed per ton of iron, thereby significantly reducing coke consumption and production costs. At the same time, it can also reduce the smelting time of iron-containing materials in the blast furnace, improve smelting efficiency, and has the effect of energy saving and consumption reduction.
[0015] Second, this invention does not use air smelting, but oxygen smelting, which avoids the problem of large amounts of nitrogen in the coal gas that exists in the traditional air smelting process. In addition to increasing the calorific value of the coal gas, it also improves the reducing ability of the coal gas, making the coal gas valuable for decarbonization and recycling. The generated coal gas can be recycled, avoiding the problem that the coal gas can only be emitted in the traditional smelting process. This avoids the waste of coal gas and the problem of large carbon dioxide emissions caused by emissions.
[0016] Third, this invention sets up two carbon cycle routes: one is a route for recycling carbon monoxide, and the other is a route for recycling carbon dioxide. When recycling carbon monoxide, the coal gas undergoes purification treatment including dust removal and dehumidification, and then carbon dioxide is separated out, leaving carbon monoxide and hydrogen as the main components. A portion of the coal gas is then burned to generate high temperatures, which heat the reducing gases (carbon monoxide and hydrogen) before returning to the indirect reduction zone of the blast furnace for continued recycling. This route involves physical separation and heating of the coal gas, directly recycling carbon monoxide and hydrogen. When recycling carbon dioxide, the carbon dioxide obtained from the separation and combustion processes is mixed with hydrogen and fed into a reactor. Under high-temperature catalysis, carbon dioxide and hydrogen react to produce carbon monoxide. The carbon monoxide and unreacted hydrogen are then fed as reducing gas into a pre-reducer for recycling. This route chemically treats the carbon dioxide, converting unwanted carbon dioxide into desired carbon monoxide. The added reactant is hydrogen, which is also a reducing gas required in the smelting process. No impurity gases are added, representing an indirect recycling of carbon dioxide. In summary, this invention fully recovers and utilizes carbon monoxide and carbon dioxide generated during the smelting process through two carbon cycle routes, significantly reducing carbon emissions during blast furnace ironmaking. At the same time, the use of an electrolysis water device to produce hydrogen is a carbon-free hydrogen production process, enabling this invention to achieve green and low-carbon blast furnace ironmaking.
[0017] In summary, this invention pre-reduces iron-containing materials before they enter the blast furnace for deep reduction, followed by an indirect reduction in the blast furnace's indirect reduction zone. After these two indirect reductions, the iron-containing materials exhibit a high metallization rate, reducing the amount of iron-containing material requiring direct reduction in the direct reduction zone and thus lowering coke consumption. Secondly, by introducing oxygen into the direct reduction zone, the gas no longer contains significant amounts of nitrogen. Two carbon recycling routes are then used to directly or indirectly recycle carbon monoxide and carbon dioxide, achieving carbon recycling in the blast furnace smelting process, reducing carbon emissions, and realizing green and low-carbon blast furnace ironmaking. This invention offers advantages such as decarbonization and recycling of blast furnace gas, low environmental pollution, energy saving, and green and low-carbon production. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; In the diagram: 1-Blast furnace, 2-Direct reduction zone, 3-Indirect reduction zone, 4-Gas purifier, 5-Separator, 6-Burner, 7-Carbon dioxide storage tank, 8-Heat exchange tube, 9-Oxygen storage tank, 10-Water electrolysis device, 11-Reactor, 12-Pre-reducer, 13-Cyclone separator, 14-Dehumidifier, 15-Bag filter, 16-Heat exchanger, 17-Gas mixer, 18-Oxygen removal catalyst. Detailed Implementation
[0019] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention are within the protection scope of the present invention.
[0020] like Figure 1As shown, the green and low-carbon blast furnace ironmaking system of the present invention includes a blast furnace 1 and a direct reduction zone 2 and an indirect reduction zone 3 located within the blast furnace 1. A gas purifier 4, a separator 5, and a burner 6 are sequentially connected to the gas outlet of the blast furnace 1. The gas purifier 4 is used to purify the gas by removing dust and moisture. The separator 5 is used to separate carbon dioxide from the gas. The burner 6 is used to burn the gas. In this invention, the high temperature generated by combustion is used to raise the temperature of the recycled reducing gas. The separated gas outlet of the separator 5 is connected to a carbon dioxide storage tank 7. A heat exchange tube 8 is installed inside the burner 6. The heat exchange tube 8 can be a spiral tube, a serpentine tube, or other structures, which can be selected according to actual needs. The outlet of the separator 5 is connected to the inlet of the heat exchange tube 8, and the outlet of the heat exchange tube 8 is connected to the lower part of the indirect reduction zone 3. An oxygen storage tank 9, an electrolysis water device 10, a reactor 11, and a pre-reducer 12 are installed outside the blast furnace 1. The electrolysis water device 10 is an electrochemical device that decomposes water into hydrogen and oxygen. The invention requires both hydrogen and oxygen. Hydrogen is used to form a hydrogen-rich mixed reducing gas by adding it to the coal gas, and it also reacts with carbon dioxide to produce carbon monoxide. Oxygen is used to burn coke in the direct reduction zone 2 of blast furnace 1, and it is also used to burn coal gas in burner 1. In this invention, the oxygen outlet of the water electrolysis device 10 is connected to the oxygen storage tank 9 via a pipeline. The oxygen storage tank 9 is connected to the lower part of the direct reduction zone 2 via a pipeline. The outlet of the gas purifier 4 is connected to the burner 6 via a pipeline. The outlets of the burner 6, the water electrolysis device 10, and the carbon dioxide storage tank 7 are all connected to the inlet of the reactor 11 via pipelines. The outlet of the reactor 11 is connected to the lower part of the pre-reducer 12. The bottom of the pre-reducer 12 is connected to the top of the blast furnace 1. The outlet of the pre-reducer 12 is connected to the outlet of the blast furnace 1. The hydrogen outlet of the water electrolysis device 10 is connected to the inlet of the heat exchange tube 8.
[0021] The gas purifier 4 includes a cyclone separator 13, a dehumidifier 14, and a bag filter 15 connected in sequence. The gas discharged from the pre-reducer 12 and the blast furnace 1 contains a large amount of residue, dust and other impurities. The gas is purified by the cyclone separator 13, the dehumidifier 14 and the bag filter 15 to remove dust and moisture, and to prevent these impurities from affecting the subsequent carbon dioxide separation, heating and other processing processes.
[0022] A heat exchanger 16 is installed on the pipeline between the gas purifier 4 and the separator 5. The outlet of the oxygen storage tank 9 is connected to the cold medium inlet of the heat exchanger 16, and the cold medium outlet of the heat exchanger 16 is connected to the lower part of the direct reduction zone 2. The heat exchanger 16 is used to preheat the oxygen using the waste heat in the coal gas, thereby increasing the oxygen temperature and improving the combustion efficiency of the oxygen with the coal after entering the blast furnace 1. In actual operation, other methods can also be used for oxygen preheating. The heat exchanger 16 serves as a pre-auxiliary waste heat device, which firstly makes full use of the waste heat in the coal gas, and secondly reduces the energy consumption for oxygen heating.
[0023] The cold medium outlet of heat exchanger 16 is connected to burner 6 through a branch pipe. Heat exchanger 16 is used to preheat oxygen by utilizing the waste heat in the coal gas. Part of the preheated oxygen is then introduced into burner 6, which can improve the combustion efficiency of coal gas and increase the combustion temperature.
[0024] The reactor 11 is equipped with an oxygen removal catalyst 18. To ensure that carbon monoxide can be fully combusted and thus generate sufficient heat, an excess of oxygen is usually introduced into the burner 16. Due to incomplete reaction, this oxygen is discharged along with the carbon dioxide. In this invention, carbon monoxide is generated by the reaction of carbon dioxide and hydrogen in the reactor 11, and a certain metal oxide is used as a catalyst. However, since a certain amount of oxygen is mixed in with the carbon dioxide, the catalyst will be permanently oxidized and deactivated, and the risk of explosion will also be increased. Based on the above hazards, this invention provides an oxygen removal catalyst 18 in the reactor 11 to catalyze the reaction of oxygen and hydrogen, thereby removing the oxygen before the carbon dioxide and hydrogen react.
[0025] A gas mixer 17 is installed at the gas inlet of reactor 11. The gas outlets of burner 16, water electrolysis device 10, and carbon dioxide storage tank 7 are all connected to the gas mixer 17 via pipelines. In this invention, some of the coal gas is burned in burner 16 to generate high temperature and carbon dioxide. This carbon dioxide, along with the carbon dioxide discharged from carbon dioxide storage tank 7 and the hydrogen generated by water electrolysis device 10, is fed into reactor 11. Carbon dioxide and hydrogen react in reactor 11 to generate carbon monoxide. During the reaction, if the carbon dioxide and hydrogen are not mixed evenly, the reaction efficiency will be reduced. Therefore, the gas mixer 17 is provided in this invention. The gas mixer 17 is an existing... This device is used for the uniform mixing of two or more gases. The invention introduces two streams of carbon dioxide and one stream of hydrogen into a gas mixer 17, ensuring a thorough and uniform mixing of the three gases. This has two main functions: firstly, it ensures a thorough and uniform mixing of carbon dioxide and hydrogen, allowing them to fully and evenly contact the catalyst surface, thus ensuring efficient reaction; secondly, of the three gases, only the carbon dioxide discharged from the burner 16 has a high temperature. To meet the reaction requirements in the subsequent reactor 11, the mixture of the three gases must be kept at a temperature that meets the reaction requirements. In actual production, the proportions of the three gases added are controlled to ensure that the mixture meets the temperature requirements of the reaction.
[0026] The smelting process of the green and low-carbon blast furnace ironmaking system described in this invention includes the following steps: ① Pre-reduction reaction: After mixing the iron-containing material with coke, it is added to the pre-reducer 12 in batches from the top. At the same time, high-temperature reducing gases carbon monoxide and hydrogen are introduced from the bottom of the pre-reducer 12. They come into countercurrent contact with the downward-moving iron-containing material and a gas-solid phase reaction occurs, which removes oxygen from the iron-containing material and carries out a pre-reduction reaction on the iron-containing material.
[0027] ② Blast furnace ironmaking: The iron-containing materials and coke after the reaction in step ① are added to blast furnace 1 from the top. In the indirect reduction zone 3 of blast furnace 1, reducing gases carbon monoxide and hydrogen are introduced, and oxygen is introduced into the direct reduction zone 2 of blast furnace 1. The coke is burned, generating carbon monoxide, carbon dioxide, hydrogen and other gases and releasing a large amount of heat. The liquid iron oxide that has not been completely reduced by indirect means comes into direct contact with the hot coke. After reduction, the iron-containing materials are reduced to molten iron.
[0028] ③ Carbon monoxide recycling: The coal gas generated during the smelting processes in steps ① and ② is passed from the pre-reducer 12 and the gas outlet at the top of the blast furnace 1 into the gas purifier 4 to remove residues, dust, and moisture from the coal gas. The purified coal gas is then passed into the separator 5 to remove carbon dioxide, forming a reducing gas with carbon monoxide and hydrogen as the main components. At the same time, hydrogen is produced using the water electrolysis device 10, and the hydrogen is mixed into the reducing gas to produce a hydrogen-rich mixed reducing gas, which is then passed into the heat exchange tube 8 in the burner 6. Meanwhile, a portion of the purified coal gas is separated through pipelines and passed into the burner 6 for combustion, generating high temperatures to heat the hydrogen-rich mixed reducing gas in the heat exchange tube 8. The heated hydrogen-rich mixed reducing gas is then returned to the indirect reduction zone 3 of the blast furnace 1, realizing the recycling of carbon monoxide. The hydrogen-rich mixed reducing gas contains 60%–90% hydrogen and 10%–40% carbon monoxide.
[0029] ④ Carbon dioxide recycling: In step ③, the coal gas is burned in the burner 6 to produce high-temperature carbon dioxide. The separator 5 separates the carbon dioxide from the coal gas. This carbon dioxide, along with some of the hydrogen produced by the water electrolysis device 10, is fed into the reactor 11. Using a metal oxide as a catalyst, the carbon dioxide and hydrogen react in the reactor to produce carbon monoxide. The carbon monoxide and unreacted hydrogen are fed into the pre-reducer 12 as reducing gases to achieve the recycling of carbon dioxide. The metal oxide is a copper-based catalyst or an iron-based catalyst.
[0030] ⑤ Slag discharge: The molten iron and slag generated in blast furnace 1 are discharged from the tapping port and slag discharge port.
[0031] This invention incorporates a pre-reducer 12, which pre-reduces iron-containing materials, ensuring that the materials undergo a certain degree of reduction before entering the blast furnace. At this point, the metallization rate of the iron-containing materials reaches 40%–50%. Subsequently, the materials are added to blast furnace 1 for deep reduction, undergoing another indirect reduction reaction in the indirect reduction zone 3 of blast furnace 1, resulting in a metallization rate of 85%–95%. Finally, a direct reduction reaction is carried out in the direct reduction zone 2 of blast furnace 1. This significantly reduces the amount of iron-containing materials that need to be processed by direct reduction, reduces the heat required for direct reduction of iron-containing materials, and reduces the amount of coke and fuel consumed per ton of iron, thereby significantly reducing coke consumption and production costs. At the same time, it can also reduce the smelting time of iron-containing materials in blast furnace 1, improving smelting efficiency and achieving energy conservation and consumption reduction.
[0032] This invention does not use air smelting, but rather oxygen smelting, which avoids the problem of large amounts of nitrogen in the coal gas present in traditional air smelting processes. In addition to increasing the calorific value of the coal gas, it also improves the reducing ability of the coal gas, making the coal gas valuable for decarbonization and recycling. The generated coal gas can be recycled, avoiding the problem of only being able to emit coal gas in traditional smelting processes. This avoids coal gas waste and the problem of large carbon dioxide emissions caused by emissions.
[0033] This invention establishes two carbon cycle routes: one for recycling carbon monoxide and the other for recycling carbon dioxide. When recycling carbon monoxide, the coal gas undergoes dust removal and dehumidification purification, and then the carbon dioxide is separated out, leaving carbon monoxide and hydrogen as the main components. A portion of the coal gas is then burned to generate high temperatures, which heat the reducing gases (carbon monoxide and hydrogen). Finally, the gas is returned to the indirect reduction zone 3 of blast furnace 1 for continued recycling. This route involves physical separation and heating of the coal gas, directly recycling carbon monoxide and hydrogen. When recycling carbon dioxide, the carbon dioxide obtained from the separation and combustion processes is mixed with hydrogen and fed into reactor 11. Under high-temperature catalysis, carbon dioxide and hydrogen react to produce carbon monoxide. The carbon monoxide and unreacted hydrogen are then fed into the pre-reducer 12 as reducing gas for recycling. This route chemically treats the carbon dioxide, converting unwanted carbon dioxide into desired carbon monoxide. The added reactant is hydrogen, which is also a reducing gas required in the smelting process. No impurity gases are added, representing an indirect recycling of carbon dioxide. In summary, this invention fully recovers and utilizes carbon monoxide and carbon dioxide generated during the smelting process through two carbon cycle routes, significantly reducing carbon emissions during blast furnace ironmaking. At the same time, the use of water electrolysis device 10 to produce hydrogen is a carbon-free hydrogen production process, enabling this invention to achieve a green and low-carbon production process for the entire blast furnace ironmaking process.
[0034] In summary, this invention pre-reduces the iron-containing material using a pre-reducer 12 before it enters the blast furnace 1 for deep reduction, and then performs an indirect reduction in the indirect reduction zone 3 of the blast furnace 1. After two indirect reductions, the iron-containing material has a high metallization rate, reducing the amount of iron-containing material that needs to be directly reduced in the direct reduction zone 2, thereby reducing coke consumption. Secondly, this invention introduces oxygen into the direct reduction zone 2, eliminating the presence of large amounts of nitrogen in the gas. Then, two carbon recycling routes are used to directly or indirectly recycle carbon monoxide and carbon dioxide, respectively, achieving carbon recycling in the blast furnace 1 smelting process, reducing carbon emissions, and realizing green and low-carbon ironmaking in the blast furnace 1.
Claims
1. A green and low-carbon blast furnace ironmaking system, comprising a blast furnace (1) and a direct reduction zone (2) and an indirect reduction zone (3) located within the blast furnace (1), characterized in that... The blast furnace (1) is connected in sequence to a gas purifier (4), a separator (5), and a burner (6) at its outlet. The separated gas outlet of the separator (5) is connected to a carbon dioxide storage tank (7). A heat exchange tube (8) is installed inside the burner (6). The outlet of the separator (5) is connected to the inlet of the heat exchange tube (8). The outlet of the heat exchange tube (8) is connected to the lower part of the indirect reduction zone (3). An oxygen storage tank (9), an electrolysis water device (10), a reactor (11), and a pre-reducer (12) are installed on the outside of the blast furnace (1). The oxygen storage tank (9) is connected to the direct reduction zone (2) via a pipeline. The lower part of the gas purifier (4) is connected to the burner (6) through a pipeline. The gas outlet of the burner (6), the hydrogen outlet of the water electrolysis device (10) and the gas outlet of the carbon dioxide storage tank (7) are all connected to the gas inlet of the reactor (11) through pipelines. The gas outlet of the reactor (11) is connected to the lower part of the pre-reducer (12). The bottom of the pre-reducer (12) is connected to the top of the blast furnace (1). The gas outlet of the pre-reducer (12) is connected to the gas outlet of the blast furnace (1). The hydrogen outlet of the water electrolysis device (10) is connected to the inlet of the heat exchange tube (8).
2. The green and low-carbon blast furnace ironmaking system according to claim 1, characterized in that... The gas purifier (4) includes a cyclone separator (13), a dehumidifier (14), and a bag filter (15) connected in sequence.
3. The green and low-carbon blast furnace ironmaking system according to claim 1, characterized in that... A heat exchanger (16) is installed on the pipeline between the gas purifier (4) and the separator (5). The outlet of the oxygen storage tank (9) is connected to the cold medium inlet of the heat exchanger (16), and the cold medium outlet of the heat exchanger (16) is connected to the lower part of the direct reduction zone (2).
4. A green and low-carbon blast furnace ironmaking system according to claim 3, characterized in that... The cold medium outlet of the heat exchanger (16) is connected to the burner (6) through a branch pipe.
5. A green and low-carbon blast furnace ironmaking system according to claim 4, characterized in that... The reactor (11) is equipped with an oxygen removal catalyst (18).
6. A green and low-carbon blast furnace ironmaking system according to claim 1, characterized in that... The reactor (11) is equipped with a gas mixer (17) at the inlet end. The outlet of the burner (16), the outlet of the water electrolysis device (10) and the outlet of the carbon dioxide storage tank (7) are all connected to the gas mixer (17) through pipelines.
7. The smelting process of a green and low-carbon blast furnace ironmaking system according to claim 1, characterized in that: Includes the following steps: ① Pre-reduction reaction: After mixing the iron-containing material with coke, add it to the pre-reducer (12) in batches from the top. At the same time, high-temperature reducing gas carbon monoxide and hydrogen are introduced from the bottom of the pre-reducer (12) to come into countercurrent contact with the downward-moving iron-containing material and a gas-solid phase reaction occurs, which removes the oxygen in the iron-containing material and carries out a pre-reduction reaction on the iron-containing material. ② Blast furnace ironmaking: The iron-containing materials and coke after the reaction in step ① are added to the blast furnace (1) from the top. In the indirect reduction zone (3) of the blast furnace (1), reducing gases carbon monoxide and hydrogen are introduced, and oxygen is introduced into the direct reduction zone (2) of the blast furnace (1). The coke is burned to generate carbon monoxide, carbon dioxide, hydrogen and other gases and release a large amount of heat. The liquid iron oxide that has not been completely reduced by indirect means comes into direct contact with the hot coke. The iron-containing materials are reduced to obtain molten iron. ③ Carbon monoxide recycling: The coal gas generated in the smelting process in steps ① and ② is introduced into the gas purifier (4) from the coal gas outlet at the top of the pre-reducer (12) and the blast furnace (1) to remove the residue, dust and moisture in the coal gas. The purified coal gas is introduced into the separator (5) to remove carbon dioxide from the coal gas and form a reducing gas with carbon monoxide and hydrogen as the main components. At the same time, hydrogen is produced by the water electrolysis device (10). The hydrogen is mixed into the reducing gas to produce hydrogen-rich mixed reducing gas, which is introduced into the heat exchange tube (8) in the burner (6). Meanwhile, a portion of the purified coal gas is separated through the pipeline and introduced into the burner (6) for combustion, generating high temperature to heat the hydrogen-rich mixed reducing gas in the heat exchange tube (8). The heated hydrogen-rich mixed reducing gas is returned to the indirect reduction zone (3) of the blast furnace (1) to realize the recycling of carbon monoxide. ④ Carbon dioxide recycling: In step ③, the coal gas is burned in the burner (6) to produce high-temperature carbon dioxide. The separator (5) separates the carbon dioxide from the coal gas. These carbon dioxide and some of the hydrogen produced by the water electrolysis device (10) are fed into the reactor (11). Using metal oxide as a catalyst, carbon dioxide and hydrogen react in the reactor to produce carbon monoxide. Carbon monoxide and unreacted hydrogen are fed into the pre-reducer (12) as reducing gas to realize the recycling of carbon dioxide. ⑤ Slag discharge: The molten iron and slag generated in the blast furnace (1) are discharged from the tapping port and the slag discharge port.
8. The smelting process of a green and low-carbon blast furnace ironmaking system according to claim 7, characterized in that: In step ③, the hydrogen-rich mixed reducing gas contains 60% to 90% hydrogen and 10% to 40% carbon monoxide.
9. The smelting process of a green and low-carbon blast furnace ironmaking system according to claim 7, characterized in that: In step ④, the metal oxide is a copper-based catalyst or an iron-based catalyst.