A blast furnace carbon emission reduction ironmaking system and a carbon emission reduction method

Abstract

This invention belongs to the field of blast furnace carbon emission reduction technology and discloses a blast furnace carbon emission reduction ironmaking system and method, including: oxygen-enriched ironmaking with the participation of a mixed reaction gas with high CO2 concentration. Due to the use of CO2 in the blast furnace blast and pulverized coal carrier gas, the oxygen enrichment rate is increased, and the amount of biochar is increased, thereby improving the smelting intensity of the blast furnace, increasing the proportion of pulverized coal replacing coke (increasing the coal ratio and decreasing the coke ratio), reducing ironmaking costs, and reducing carbon emissions. Furthermore, due to the use of CO2 injection and oxygen-enriched ironmaking operations, the amount of air incorporated into the mixed reaction gas is reduced, increasing the concentration of CO and CO2 in the blast furnace gas, which is beneficial for subsequent capture, separation, purification, and resource utilization of different components in the blast furnace gas.

Description

Technical Field

[0001] This invention belongs to the field of blast furnace carbon emission reduction technology, and in particular relates to a blast furnace carbon emission reduction ironmaking system and carbon emission reduction method. Background Technology

[0002] The blast furnace process accounts for approximately 60% of the total energy consumption in the steelmaking process. Blast furnaces are both major energy consumers and major emitters in the steel industry. The blast furnace and its upstream processes primarily use coke and pulverized coal as fuel, resulting in enormous consumption. Therefore, ultra-low emission retrofitting of these furnaces will be a key focus.

[0003] The chemical industry has high requirements for gas purity. CO2 and CO gas that meet industrial purity requirements should be used as chemical raw materials. However, the CO content in blast furnace gas is about 20%~28%, the CO2 content is about 17%~25%, the N2 content is about 50%~55%, and the H2 content is about 1%~2%. The blast furnace gas of conventional blast furnaces is not suitable for chemical synthesis production. Summary of the Invention

[0004] The purpose of this invention is to provide a blast furnace carbon emission reduction ironmaking system and carbon emission reduction method to solve the problems existing in the prior art.

[0005] To achieve the above objectives, this invention provides a blast furnace carbon emission reduction ironmaking system that uses CO2 as the blast medium and pulverized coal injection carrier gas in the blast furnace, while simultaneously injecting a mixed fuel composed of biomass char and pulverized coal into the blast furnace. The system recycles the blast furnace top gas and uses a portion of the blast furnace gas for iron and steel-chemical co-production to produce high value-added products, specifically including:

[0006] Blast furnace, wherein the blast furnace is connected to a hot blast stove and a pulverized coal silo;

[0007] The gas source module includes a CO2 gas source, an O2 gas source, and an air gas source. The gas source module is connected to the hot air furnace and is used to supply gas to the hot air furnace to heat the gas into a high-temperature mixed reaction gas.

[0008] A biomass pyrolysis device is used to obtain biochar. The obtained biochar is fed into a pulverized coal silo and mixed with pulverized coal to form a fuel-biochar mixed fuel. The fuel-biochar mixed fuel and high-temperature mixed reaction gas are fed into a blast furnace for combustion and reduction reactions to generate blast furnace gas.

[0009] A gas separation device is connected to the blast furnace and is used to separate blast furnace gas to obtain CO and CO2. The separated CO2 is returned to the hot blast stove or supplied externally, and the separated CO is supplied externally.

[0010] Optionally, it also includes a blower-mixing device, one end of which is connected to a hot air furnace and the other end to a gas source module.

[0011] Optionally, the bottom of the blast furnace is provided with a jet injection device, one end of which is connected to the blast furnace and the other end of which is connected to the pulverized coal silo.

[0012] Optionally, the system recycles blast furnace gas as follows: a portion of the blast furnace gas is used for combustion and power generation; the remaining blast furnace gas is separated into CO2 gas and high-quality blast furnace gas by a gas separator; a portion of the high-quality blast furnace gas is sent to a hot blast stove for combustion to heat the injected gas; another portion of the high-quality blast furnace gas is extracted into CO gas by a CO capture device; a portion of the separated CO2 gas is returned to the CO2 gas source as carrier gas and blast gas for pulverized coal injection in the blast furnace; the remaining separated CO2 gas and all of the CO gas are used as chemical raw materials.

[0013] Optionally, since CO2 absorbs heat when it reacts with the mixed fuel in the blast furnace tuyeres, heat compensation can be achieved by increasing the oxygen enrichment rate of the blast furnace, thereby enhancing the smelting intensity of the blast furnace and achieving stable operation of the blast furnace under high oxygen enrichment conditions. In addition, biomass charcoal has good combustibility and a high burnout rate when mixed with CO2, which is conducive to the full combustion of pulverized coal in the tuyeres area. At the same time, CO2 injection enables the blast furnace to absorb some of the CO2 it produces, thereby reducing carbon emissions.

[0014] On the other hand, to achieve the above objectives, the present invention provides a blast furnace carbon emission reduction ironmaking method, applied to the aforementioned blast furnace carbon emission reduction ironmaking system, comprising:

[0015] Step 1: Agricultural waste such as straw is pyrolyzed in a biomass pyrolysis device to obtain biochar with a fixed carbon content of more than 70%. In the pulverized coal silo, the biochar is mixed in a ratio of 5% to 40% and used as blast furnace injection fuel - biochar mixed fuel.

[0016] Step 2: CO2 is used as a carrier gas to form a CO2-coal powder fuel mixture with biochar and coal powder to form a CO2-coal powder fuel mixture, which is then introduced into the blast furnace body through the coal injection pipe and the coal powder injection device.

[0017] Step 3: Gas is supplied to the blast mixing device from CO2, O2 and air sources. The mixed reaction gas is produced with CO2 injection ratio of 20% to 30%, O2 injection ratio of 40% to 60% and air injection ratio of 10% to 40%. The mixed reaction gas enters the hot blast stove and is heated to a high temperature mixed reaction gas. Then, it enters the blast furnace tuyer through the hot blast pipe and reacts with biomass char mixed with pulverized coal.

[0018] Step 4: Iron ore, coke and flux are added by the blast furnace charging system. In the countercurrent process (the charge descends and the gas rises), a complex physicochemical reaction is completed. Finally, the reaction produces molten iron and slag, which are discharged from the tapping / slag outlet.

[0019] Step 5: After the high-temperature mixed reaction gas and the CO2-biochar mixed pulverized coal flow enter the blast furnace body, they react with coke in the tuyeres area to generate reducing gas with a CO concentration of 70% to 90%. The reducing gas rises and passes through the dripping zone, softening zone, and blocky zone in sequence, reacting with the descending ore to generate high-quality blast furnace gas with a CO concentration of 15% to 50% and a CO2 concentration of 10% to 40%.

[0020] Step 6: Part of the blast furnace gas is used for combustion power generation, and the remainder is separated into CO2 and high-quality blast furnace gas through a gas separation device. Part of the high-quality blast furnace gas is used to heat the injection gas in the hot blast stove, and the remaining high-quality blast furnace gas is passed through a CO capture device to obtain CO gas. Part of the CO2 is recycled to the CO2 gas source as the carrier gas and blast gas for the pulverized coal injected into the blast furnace, and the remaining CO2 gas and all of the CO gas are used as chemical raw materials.

[0021] Optionally, biochar is produced by pyrolyzing agricultural waste in a biomass pyrolysis unit and then mixing it with bituminous coal and anthracite in a pulverized coal bin before using it as fuel for blast furnace injection, thereby enabling the blast furnace to absorb agricultural waste and reduce carbon emissions.

[0022] Because biochar has a low ignition temperature and a fast combustion speed, mixing biochar with pulverized coal for injection can significantly improve the combustion performance of pulverized coal fuel and reduce the amount of unburned carbon produced in coke, thereby protecting the coke. In addition, injecting biochar can increase the amount of pulverized coal injected, increase the proportion of pulverized coal replacing coke (increase the coal ratio and reduce the coke ratio), save ironmaking costs, and according to the whole life cycle analysis, injecting biochar helps to reduce CO2 emissions in the blast furnace ironmaking process.

[0023] Optionally, biochar can be mixed with anthracite and bituminous coal to form a mixed fuel for injection, and CO2 can be used as the blast gas and carrier gas for the mixed fuel. This can help increase the O2 content in the blast furnace blast, thereby reducing the coke ratio, increasing the smelting intensity, reducing carbon emissions in ironmaking, and obtaining high-quality blast furnace gas for use as raw material gas for steelmaking co-production, thus enabling the steel plant to produce high value-added products.

[0024] This method increases the CO and CO2 content in the blast furnace gas, which is beneficial for separating, purifying, and capturing CO and CO2 in the gas in subsequent processes. Furthermore, the CO2 produced by the blast furnace can be used for steel-chemical co-production, which not only reduces the company's carbon emissions but also provides a way for the company to increase the added value of its products.

[0025] The technical effects of this invention are as follows:

[0026] This invention utilizes an oxygen-enriched ironmaking process with a high-CO2 concentration mixed reaction gas. The increased use of CO2 in the blast furnace and pulverized coal carrier gas, coupled with higher oxygen enrichment and biochar content, enhances the blast furnace's smelting intensity, increases the proportion of pulverized coal replacing coke (increasing the coal ratio and decreasing the coke ratio), lowers ironmaking costs, and reduces carbon emissions. Furthermore, the reduced air incorporation in the mixed reaction gas due to CO2 injection and oxygen-enriched ironmaking operations increases the concentration of CO and CO2 in the blast furnace gas, facilitating subsequent capture, separation, purification, and resource utilization of different components within the blast furnace gas. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0029] Figure 1 This is a schematic diagram of the structure of the blast furnace carbon emission reduction ironmaking system in an embodiment of the present invention.

[0030] Labeling Explanation: 1. Biomass pyrolysis device; 2. Pulverized coal silo; 3. Pulverized coal injection device; 4. Coal gas separation device; 5. CO capture device; 6. Hot blast furnace; 7. Blower gas mixing device; 8. O2 gas source; 9. Air gas source; 10. CO2 gas source. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a blast furnace carbon emission reduction ironmaking system, including: a blast furnace, a CO2 gas source 10, an O2 gas source 8, an air gas source 9, a blower mixing device 7, a biomass pyrolysis device 1, a pulverized coal silo 2, a pulverized coal injection device 3, a gas separator 4, a CO capture device 5, a hot blast stove 6, and auxiliary pipelines, wherein:

[0038] Blast furnace, wherein the blast furnace is connected to a hot blast stove 6 and a pulverized coal silo 2 respectively;

[0039] The gas source module includes a CO2 gas source 10, an O2 gas source 8, and an air gas source 9. The gas source module is connected to the hot air furnace 6 and is used to supply gas to the hot air furnace 6 to heat the gas into a high-temperature mixed reaction gas.

[0040] Biomass pyrolysis device 1 is used to obtain biochar. The obtained biochar is fed into pulverized coal bin 2 and mixed with pulverized coal to form fuel-biochar mixed fuel. The fuel-biochar mixed fuel and high-temperature mixed reaction gas are fed into blast furnace for combustion and reduction reactions to generate blast furnace gas.

[0041] The gas separation device 4 is connected to the blast furnace and is used to separate the blast furnace gas to obtain CO and CO2. The separated CO2 is returned to the hot blast stove 6 or supplied externally, and the separated CO is supplied externally.

[0042] The implementable component also includes a blower-mixing device 7, one end of which is connected to the hot air furnace 6 and the other end is connected to the gas source module.

[0043] It is feasible to install a jet injection device at the bottom of the blast furnace, with one end of the jet injection device connected to the blast furnace and the other end connected to the pulverized coal silo 2.

[0044] This embodiment also provides a processing scheme for steel-chemical co-production, where blast furnace gas, after being treated at the top of the furnace, can be separated into three gaseous products: high-quality blast furnace gas, pure CO2 gas, and pure CO gas. A portion of the pure CO2 gas is recycled back to the CO2 gas source 10 as carrier gas for blast furnace injection fuel and blast gas; the remaining CO2 gas and all of the CO gas are used as raw materials for chemical production. The high-quality blast furnace gas is then fed into the combustion reaction to heat the blast gas.

[0045] The specific implementation steps include:

[0046] Step 1: Agricultural waste such as straw is pyrolyzed by biomass pyrolysis device 1 to obtain biochar with a fixed carbon content of more than 70%. In the coal powder bin 2, the biochar is mixed in a ratio of 5% to 40% and used as blast furnace injection fuel - biochar mixed fuel.

[0047] Step 2: CO2 is used as a carrier gas to form a CO2-coal powder fuel mixture with biochar and coal powder to form a CO2-coal powder fuel mixture, which is then introduced into the blast furnace body through the coal powder injection device 3 along the coal injection pipeline.

[0048] Step 3: Gas is supplied to the blast mixing device 7 from CO2 source 10, O2 source 8 and air source 9. The mixed reaction gas is produced according to the injection ratio of CO2 of 20%~30%, O2 of 40%~60% and air of 10%~40%. The mixed reaction gas enters the hot blast stove 6 and is heated to a high temperature mixed reaction gas in the hot blast stove 6. Then, it enters the tuyeres of the blast furnace through the hot blast pipe and reacts with the biomass char mixed with pulverized coal.

[0049] Step 4: Iron ore, coke and flux are added by the blast furnace charging system. In the countercurrent process (the charge descends and the gas rises), a complex physicochemical reaction is completed. Finally, the reaction produces molten iron and slag, which are discharged from the tapping / slag outlet.

[0050] Step 5: After the mixed flow of high-temperature mixed reaction gas, CO2, biochar, and pulverized coal enters the blast furnace body, it undergoes a combustion reaction with coke in the tuyeres area, generating reducing gas with a CO concentration of 70% to 90%. The reducing gas rises and passes through the dripping zone, softening zone, and blocky zone in sequence, reacting with the descending ore to generate high-quality blast furnace gas with a CO concentration of 35% to 50% and a CO2 concentration of 30% to 45%.

[0051] Step 6: Part of the blast furnace gas is used for combustion power generation, and the remainder is separated into CO2 and high-quality blast furnace gas through the gas separation device 4. Part of the high-quality blast furnace gas is used to enter the hot blast stove 6 to heat the injected gas, and the remaining high-quality blast furnace gas is passed through the CO capture device 5 to obtain CO gas. Part of the CO2 is recycled to the CO2 gas source 10 as the carrier gas and blast gas for the pulverized coal injected into the blast furnace, and the remaining CO2 gas and all CO gas are used as chemical raw materials.

[0052] In summary, this embodiment uses biomass injection to replace a portion of the bituminous coal in an appropriate proportion, improving the overall combustion performance of pulverized coal, reducing the amount of unburned carbon in the tuyere swirl zone, and lowering the coke ratio and CO2 emissions. Secondly, this embodiment mixes CO2 into the blast gas and uses CO2 as the carrier gas for the injected pulverized coal. This allows the pulverized coal in the tuyere swirl zone to react with CO2 to generate more CO and absorb heat. Furthermore, by enriching the blast gas with oxygen, the O2 concentration in the blast is increased, accelerating the combustion of carbon before the tuyere, improving the blast furnace's smelting efficiency, and enhancing the quality of the blast furnace gas. In addition, the increased concentration of CO and CO2 in the blast furnace gas reduces the cost of its capture and utilization. Choosing a reasonable co-production method not only reduces CO2 emissions but also generates revenue for the enterprise from the sale of high-value-added chemical products.

[0053] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A blast furnace carbon emission reduction ironmaking system, characterized in that, include The blast furnace is connected to a hot blast stove (6) and a pulverized coal bin (2). Gas source module, the gas source module is connected to the hot air furnace (6), the gas source module is used to supply gas to the hot air furnace (6) and heat it in the hot air furnace (6) to form a high temperature mixed reaction gas; Biomass pyrolysis device (1), the biomass pyrolysis device (1) is used to obtain biochar, the obtained biochar is fed into the coal powder bin (2) and mixed with coal powder to form fuel-biochar mixed fuel; the fuel-biochar mixed fuel uses CO2 as carrier gas and enters the blast furnace together with high temperature mixed reaction gas to carry out combustion reaction and reduction reaction to generate blast furnace gas; The gas separation device (4) is connected to the blast furnace and is used to separate the blast furnace gas to obtain CO and CO2. The separated CO2 is sent back to the gas source module or externally supplied, and the separated CO is supplied externally.

2. The blast furnace carbon emission reduction ironmaking system according to claim 1, characterized in that, It also includes a blower gas mixing device (7), one end of which is connected to a hot air furnace (6) and the other end is connected to a gas source module.

3. The blast furnace carbon emission reduction ironmaking system according to claim 1, characterized in that, The bottom of the blast furnace is equipped with a jet injection device, one end of which is connected to the blast furnace and the other end is connected to the pulverized coal silo (2).

4. The blast furnace carbon emission reduction ironmaking system according to claim 1, characterized in that, The gas source module includes an O2 gas source (8), an air gas source (9), and a CO2 gas source (10).

5. A carbon emission reduction method, applied to a blast furnace carbon emission reduction ironmaking system according to any one of claims 1-4, characterized in that, include: S1: Agricultural waste is fed into the biomass pyrolysis device (1), and biochar is obtained after being processed by the biomass pyrolysis device (1). The obtained biochar is fed into the coal powder silo (2). The biochar is mixed in the coal powder silo (2) at a ratio of 5% to 40% and used as fuel for the blast furnace - biochar mixed fuel. S2: CO2 is used as the carrier gas. The carrier gas and the fuel-biomass char mixed fuel form a CO2-pulverized coal fuel mixture. The CO2-pulverized coal fuel mixture enters the blast furnace through the pulverized coal injection device (3). S3: O2 gas source (8), air gas source (9) and CO2 gas source (10) supply gas to the blower mixing device (7) to produce mixed reaction gas. The mixed reaction gas enters the hot air furnace (6) and is heated in the hot air furnace (6) to become high temperature mixed reaction gas. S4: Add iron ore, coke and flux to the blast furnace to form blocky bands, softening bands and dripping bands depending on the furnace conditions; S5: After the high-temperature mixed reaction gas and CO2-pulverized coal fuel mixture enter the blast furnace, it reacts with coke in the tuyer area to generate reducing gas. The reducing gas rises and passes through the dripping zone, softening zone and blocky zone in sequence to react with the descending ore to generate blast furnace gas. S6: Supply the blast furnace gas in a preset proportion to external users, and input the remaining blast furnace gas into the gas separation device (4) for separation to obtain CO2 and high-quality blast furnace gas for recycling or external supply.

6. A carbon emission reduction method according to claim 5, characterized in that, In step S3, the proportion of CO2 injected into the mixed reaction gas is 20%~30%, the proportion of O2 injected is 40%~60%, and the proportion of air injected is 10%~40%.

7. A carbon emission reduction method according to claim 5, characterized in that, In step S6, the specific steps of recycling or externally supplying the separated CO2 include: inputting a preset proportion of CO2 into the gas source module, and externally supplying the remaining CO2.

8. A carbon emission reduction method according to claim 5, characterized in that, In step S6, the specific steps of recycling or supplying the separated high-quality blast furnace gas include: inputting a preset proportion of high-quality blast furnace gas into the hot blast stove (6) to heat the injected gas, and obtaining CO gas through the CO capture device (5) and supplying it to the outside.

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