Method for operating a blast furnace

Abstract

The invention relates to a method for operating a blast furnace. In order to provide an optimized blast furnace operation, the invention provides that the method comprises collecting blast furnace gas from the blast furnace (12), the blast furnace gas being a gas containing CO2, combining the blast furnace gas with a fuel gas to obtain a gas mixture, the fuel gas being a gas containing hydrocarbons, subjecting the gas mixture to a reforming process, thereby generating a synthesis gas containing CO and H2, and feeding at least a part of the synthesis gas and an oxygen-rich gas (26) into the blast furnace (12), wherein the blast furnace gas is combined with the fuel gas while containing substantially the same amount of CO2 as when it leaves the blast furnace, and the blast furnace gas is combined with the fuel gas in a hyperstoichiometric ratio, such that the synthesis gas contains an excess part of the blast furnace gas.

Description

[0001] This application is a divisional application of Chinese invention patent application number "202080037145.2". The original application was filed on May 19, 2020 (PCT international application date), with Chinese national application number "202080037145.2" (PCT international application number is PCT / EP2020 / 063952), and the invention title is "Method for Operating a Blast Furnace". Technical Field

[0002] The present invention relates to a method for operating a blast furnace. Background Technology

[0003] Despite alternative methods, such as waste melting in electric arc furnaces or direct reduction, blast furnaces remain the most widely used process in steel production today. One of the key concerns with blast furnace systems is the blast furnace gas exiting the furnace. Because this gas exits the blast furnace at the top, it is often referred to as "top gas." While in the past this gas may have been allowed to simply escape into the atmosphere, this has long been considered a waste of resources and an excessive burden on the environment. One component of blast furnace gas is CO2, which is harmful to the environment and primarily useless for industrial applications. In fact, blast furnace gas exiting the furnace typically contains as much as 20% to 50% CO2. In addition, blast furnace gas usually contains considerable amounts of N2, CO, H2O, and H2. However, the N2 content depends heavily on whether hot air or (pure) oxygen is used in the blast furnace.

[0004] Primarily to reduce coke consumption, the following suggestion has been made: recover blast furnace gas, process it to enhance its reducing potential, and inject it back into the blast furnace to aid the reduction process. One method for doing this is to reduce the CO2 content in blast furnace gas using pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA), as disclosed in patent application EP 2 886 666 A1. PSA / VPSA facilities generate a first gas stream rich in CO and H2, and a second gas stream rich in CO2 and H2O. The first gas stream can be used as a reducing gas and is fed back into the blast furnace. An example of this method is the ULCOS (Ultra Low CO2 Steelmaking) process, in which pulverized coal and cold oxygen are fed into the blast furnace in addition to the recovered first gas stream. This type of furnace is also known as a "top gas recovery OBF" (oxygen blast furnace).

[0005] The second gas stream can be removed from the facility and disposed of after the remaining calorific value has been extracted. The controversy surrounding this disposal lies in pumping the CO2-rich gas into underground containers for storage. Furthermore, while PSA / VPSA facilities can significantly reduce the CO2 content in blast furnace gas from approximately 35% to approximately 5%, these facilities are very expensive to acquire, maintain, and operate, and they require substantial space.

[0006] It has also been proposed to reform blast furnace gas to obtain syngas (also known as synthesis gas) that can be used for various industrial purposes. According to the most common reforming processes (such as the reforming process disclosed in WO 2019 / 057930 A1), blast furnace gas is mixed with fuel gas containing at least one hydrocarbon (e.g., CH4 and hydrocarbons with potentially higher molecular weights). In the so-called dry reforming reaction, the hydrocarbons in the fuel gas react with CO2 in the blast furnace gas to produce H2 and CO. In the so-called wet reforming reaction, the hydrocarbons react with H2O in the blast furnace gas, also producing H2 and CO. Regardless of the method, a syngas with significantly increased concentrations of H2 and CO is obtained. It has also been proposed to use this syngas as a reducing gas, which can be recycled, i.e., reintroduced into the blast furnace. According to one process, the syngas is fed into the blast furnace along with hot blast (i.e., hot air) and pulverized coal. This type of furnace can also be called a "syngas blast furnace". Summary of the Invention

[0007] Technical issues: Therefore, the object of the present invention is to provide an optimized blast furnace operation. This object is achieved by a method for operating a blast furnace, the method comprising: - Collect blast furnace gas from the blast furnace, the blast furnace gas being a gas containing CO2; - Combining blast furnace gas with fuel gas to obtain a gas mixture, wherein the fuel gas is a gas containing hydrocarbons; - Subjecting the gas mixture to a reforming process to generate a synthesis gas containing CO and H2; and - At least a portion of the synthesis gas and oxygen-enriched gas are fed into the blast furnace. The blast furnace gas is combined with fuel gas after leaving the blast furnace without undergoing initial decarbonization; the blast furnace gas is combined with the fuel gas at an overstoichiometric ratio, such that the syngas contains an excess portion of blast furnace gas; and the overstoichiometric ratio is adjusted to control the flame temperature of the blast furnace. Invention Overview This invention provides a method for operating a blast furnace. In the first step, the method includes collecting blast furnace gas, which is a CO2-containing gas, from the blast furnace. Specifically, the blast furnace gas can have a CO2 concentration of 20% to 50%. Blast furnace gas, or BFG, can also be referred to as top gas because it is obtained from the top of the blast furnace. Besides CO2, BFG may also contain other components, such as CO, H2O, H2, or other components. In particular, it can be a gas containing H2O. As will be explained below, BFG preferably has a very low N2 concentration, for example, below 20%, below 10%, or below 5%. However, generally, the N2 concentration can be between 0% and 50%. Typically, blast furnace gas needs to be purified to reduce its dust content. Furthermore, its H2O content is preferably significantly reduced by condensation. This can be done, for example, in a gas purification device where the gas temperature is lowered and water can be condensed.

[0009] The collected blast furnace gas (which has typically been purified) is then combined with a fuel gas to obtain a gas mixture containing hydrocarbons. The fuel gas can be, for example, coke oven gas (COG), natural gas, biogas, or any mixture of these gases. It typically has a high concentration of low-molecular-weight hydrocarbons, especially CH4. In the gas mixture, the blast furnace gas and the fuel gas can be mixed almost perfectly. Combining blast furnace gas with fuel gas generally means “making the blast furnace gas mixable with the fuel gas.” This can include (actively) mixing the blast furnace gas and the fuel gas, i.e., applying mechanical force to mix the gases. However, in some cases, it may be sufficient, for example, to inject both gases into a container so that mixing occurs almost passively through convection and / or diffusion. It goes without saying that the chemical reaction is enhanced due to a higher degree of mixing. It is feasible to combine the two gases in a dedicated container, which may be referred to as a mixing container or mixing chamber. When combining the collected blast furnace gas with fuel gas, it is feasible and still within the scope of this invention to add a supplementary gas to the gas mixture. The supplementary gas is preferably a gas containing CO2 and / or H2O, such as basic oxygen furnace (BOF) gas, pure stream, or pure CO2. The supplementary gas can be added to adjust the composition of the blast furnace gas.

[0010] A gas mixture undergoes a reforming process to produce a syngas containing CO and H2. The chemical mechanism of the reforming process is not limited within the scope of this invention, but it generally involves at least the reaction of the CO2 content of the blast furnace gas with hydrocarbons in the fuel gas, for example, according to the reaction: CO2 + CH4 → 2H2 + 2CO. This can also be referred to as dry reforming. Furthermore, the H2O content of the blast furnace gas can also react with hydrocarbons in the fuel gas, for example, according to the reaction: H2O + CH4 → 3H2 + CO. This can also be referred to as wet reforming. The reforming process typically requires elevated temperatures, for example, above 700°C. ° C. The process can be carried out in the same vessel used for combining (or mixing) the gases or in a dedicated reforming vessel. In particular, a regenerator can be used (for example, as described in WO 2010 / 049536 or US 4,005,986). Each of the fuel gas and blast furnace gas can be individually heated before obtaining the gas mixture. Alternatively or additionally, the obtained gas mixture can be heated to obtain or maintain the temperature required for the reforming process. The reforming process can also be carried out under elevated pressure. In this case, the gas mixture can be compressed, or the blast furnace gas and fuel gas can be individually compressed and combined. The reforming process can optionally be assisted by a catalyst typically introduced into the reforming vessel. It should be noted that although at least some of the blast furnace gas needs to be mixed with some of the fuel gas to initiate the reforming process, mixing and reforming can occur at least partially simultaneously.

[0011] In another step, at least a portion of the synthesis gas and oxygen-enriched gas are fed into the blast furnace. The oxygen-enriched gas is generally a gas with an O2 concentration much higher than that of air. Typically, the oxygen-enriched gas is primarily composed of O2, i.e., it has an O2 concentration greater than 50%. Preferably, it contains at least 60%, more preferably at least 80%, and more preferably at least 90% O2. In some cases, the oxygen-enriched gas may even be referred to as "oxygen," although it goes without saying that trace concentrations (e.g., <5%) of other components such as N2 may be unavoidable. Typically, the synthesis gas and oxygen-enriched gas are fed into the blast furnace at the tuyeres level or through at least one tuyer.

[0012] In the method of this invention, the synthesis gas, as a reducing gas, is reintroduced into the blast furnace along with the oxygen-enriched gas. It goes without saying that CO2 emissions from the blast furnace can be significantly reduced through recovery, i.e., reforming and reintroduction of the blast furnace gas. Furthermore, the method of this invention does not require PSA or VPSA. Instead, the blast furnace gas can be used in the reforming process in its untreated or unaltered state. That is, the chemical composition of the blast furnace gas does not need to be altered between collection from the blast furnace and the reforming process. In other words, unlike the method disclosed in EP 2 886 666 A1, the method of this invention does not require preliminary decarbonizing of the blast furnace gas. In other words, the blast furnace gas combines with the fuel gas while containing substantially the same amount of CO2 as when it leaves the blast furnace. Furthermore, because the oxygen-enriched gas contains far less N2 than air, the concentration of reducing gases such as CO and H2 is higher, which helps to improve the productivity of the blast furnace.

[0013] Despite the aforementioned benefits of the method of the present invention, the use of oxygen-enriched gas may potentially lead to some difficulties. On the one hand, the flame temperature will increase relative to the use of air because the nitrogen contained in the air cools the flame in the raceway (the area immediately following the gas injection point into the blast furnace). On the other hand, the top gas temperature may decrease due to the reduced amount of nitrogen, as nitrogen significantly contributes to heat transfer within the blast furnace. Therefore, proper heating and drying of the cold charge becomes difficult or impossible, leading to significant operational problems. These two problems are alleviated according to the present invention because the blast furnace gas is combined with the fuel gas in an overstoichiometric ratio, resulting in the synthesis gas containing an excess portion of the blast furnace gas. In other words, the overstoichiometric combination of blast furnace gas and fuel gas reduces both the problems of proper heating and drying of the cold charge.

[0014] In a stoichiometric reaction, the amount of oxidant—primarily CO2 and / or H2O (from the blast furnace gas and fuel gas)—in the gas mixture prior to reforming (a mixture of blast furnace gas and fuel gas) is such that its entire content is consumed in the reaction with the hydrocarbons contained in the fuel gas. For example, when the fuel gas stream contains 1 mol / s of methane (CH4), the gas mixture stream must contain exactly 1 mol / s of oxidant (CO2 and / or H2O) to convert all the methane to H2 and CO. This relationship between hydrocarbons and oxidant may vary depending on the type of hydrocarbons contained in the fuel gas. In an overstoichiometric case, on the other hand, the flow rate of oxidant (CO2 and / or H2O) in the gas mixture will be higher than in the stoichiometric case. For example, when the fuel gas stream contains 1 mol / s of methane CH4, the mixed gas stream may contain 1.2 mol / s of oxidant (CO2 and / or H2O) so that after the hydrocarbons contained in the fuel gas have completely reacted, the syngas still contains oxidant.

[0015] As proposed in this invention and unlike what is known from prior art such as WO 2019 / 057930 A1, combining blast furnace gas and fuel gas in an overstoichiometric ratio has several advantages. On the one hand, the excess portion of the blast furnace gas has the same temperature as the other components of the synthesis gas, thereby introducing additional latent heat into the furnace, thus reducing the blast furnace's fuel consumption rate. In other words, the overstoichiometric amount of blast furnace gas acts as a heat carrier within the blast furnace, thereby reducing its fuel consumption. On the other hand, it helps to increase the top gas temperature because it is the heat carrier medium within the blast furnace. In other words, the overstoichiometric amount of blast furnace gas acts as a heat carrier within the blast furnace. The excess portion of blast furnace gas thus makes it possible to regulate the top gas temperature of the blast furnace. Moreover, since the excess portion of the blast furnace gas acts as a heat carrier, it allows the reforming process to be operated at a lower temperature compared to the temperature typically required when using a reforming vessel or reforming reactor of the same size. Alternatively, at the same reaction temperature, a (small) reactor size can be maintained, allowing for a significant reduction in investment costs for syngas production units. Furthermore, the excess CO2 and / or H2O contained in the syngas due to the blast furnace gas (i.e., the fact that the blast furnace gas is combined with fuel gas in an overstoichiometric ratio) can react with C to generate CO and / or H2 in an endothermic reaction, thus lowering the flame temperature.

[0016] It is also worth mentioning that an overstoichiometry ratio can be applied to reduce undesirable reactions during the reforming process, such as soot deposition. Furthermore, the reforming reaction can be controlled by adjusting the overstoichiometry ratio.

[0017] While blast furnace gas is preferably combined with fuel gas in an overstoichiometric ratio prior to the reforming process, this does not preclude the possibility of combining blast furnace gas with fuel gas in an overstoichiometric ratio prior to the reforming process and adding additional blast furnace gas after the reforming process; such methods are still within the scope of this invention. In any case, the resulting compound supplied to the blast furnace gas may contain a significant amount of unreacted blast furnace gas.

[0018] The method of this invention can also completely eliminate the need for hot blast injection in the blast furnace. Even if hot blast injection is used (to a reduced extent), the oxygen-enriched gas is not mixed with the hot blast outside the blast furnace, but is injected separately. For example, it can be injected using a separate lance or a separate port at the tuyeres.

[0019] Preferably, the synthesis gas is fed into an inlet with a temperature of at least 800°C. ° C. Preferably at least 1000 ° A blast furnace at temperature C. In other words, the syngas is fed in as a hot gas. This may require the syngas to be heated after the reforming process. In other cases, the syngas may have a sufficiently high temperature after the reforming process so that it can be introduced into the blast furnace without additional heating. The syngas can be injected into the blast furnace at the tuyere height level, or alternatively, at the lower furnace body height level.

[0020] Meanwhile, oxygen-enriched gas can have a concentration of less than 100. ° Temperature C. In particular, oxygen-rich gas can have an ambient temperature, that is, around 15°C. ° C and 40 ° Between C. Or as an alternative, however, oxygen-enriched gas can have at least 100 ° Temperature C. Such an increase in temperature may, for example, originate from the production or preparation of oxygen-enriched gases.

[0021] According to one embodiment, the top gas temperature of the blast furnace is controlled by adjusting the stoichiometric ratio. In other words, the ratio (or stoichiometric factor) is used as a means of controlling the top gas temperature. Preferably, the top gas temperature is measured directly or indirectly, and the top gas temperature is adjusted by dynamically adapting the ratio. In other words, a closed loop is used to limit large temperature deviations.

[0022] According to another embodiment that can be combined with the above embodiments, the stoichiometric ratio is adjusted to control the flame temperature of the blast furnace. In this case, the ratio is used as a means of controlling the flame temperature. This is mainly based on the endothermic reaction of CO2 and / or H2O with, for example, coke components or auxiliary fuels that can be fed into or injected into the blast furnace. Again, the flame temperature can be measured directly or indirectly, and the flame temperature can be adjusted by adjusting the ratio.

[0023] Advantageously, auxiliary fuels, such as pulverized coal (known as pulverized coal injection (PCI)) or gases (e.g., but not limited to natural gas or coke oven gas), are fed into the blast furnace along with syngas and oxygen-enriched gases. This process is known in principle in the art. In this embodiment, the overstoichiometric amount of blast furnace gas acts as a heat carrier inside the blast furnace, advantageously allowing for an increase in the amount of auxiliary fuel fed into the blast furnace.

[0024] There are various possibilities regarding how different components can be fed into the blast furnace. As mentioned above, the syngas can be fed either at the tuyere height level or at the furnace body height level. For example, the syngas can be fed through the tuyere, while the oxygen-enriched gas and auxiliary fuel are fed through dedicated lances arranged inside the tuyere. Alternatively, the auxiliary fuel and oxygen-enriched gas can be injected through lances concentrically arranged inside the tuyere, with auxiliary fuel in the inner tube and cold oxygen in the outer tube.

[0025] Not all blast furnace gas collected from the blast furnace needs to be combined with fuel gases. In one embodiment, a portion of the blast furnace gas is burned with oxygen to produce exhaust gas. While using high-purity oxygen (O2) may be advantageous, it is not necessary. Instead, any gas or gas mixture containing a sufficient concentration of O2 can be used, possibly even air. For example, blast furnace gas may have a N2 concentration of less than 5%, approximately 40% CO and 40% CO2, and approximately 15% H2. When this gas is burned with oxygen, the exhaust gas may have a composition of approximately 80% CO2, 15% H2O, and 5% N2. More generally, blast furnace gas may have a N2 concentration of 0-50%, a CO and 20-50% CO and 2% CO2, and 2-25% H2. Of course, the composition of the exhaust gas depends on the actual composition of the blast furnace gas.

[0026] Exhaust gases or vent gases can be advantageously condensed and cooled. This further increases the CO2 concentration, for example, to 95%.

[0027] Preferably, a portion of the blast furnace gas is burned in a heating device. Such a heating device may include one or more burners and can be used for various purposes. For example, the heating device may be used to heat blast furnace gas, fuel gas, gas mixtures, and / or syngas. It may also be used to supply energy for reforming reactions. If it is used to heat syngas, this is primarily to increase the latent heat introduced into the blast furnace through the syngas.

[0028] Especially after the aforementioned condensation and cooling, the CO2 concentration in the exhaust gas is extremely high. Therefore, at least a portion of the exhaust gas can be used for carbon capture and storage. Alternatively or additionally, at least a portion of the exhaust gas can be used for carbon capture and utilization.

[0029] Additionally or alternatively, at least a portion of the exhaust gas may be used for syngas generation. Syngas generation may include reforming processes similar to or the same as those described above. For example, this could be dry reforming, in which CO2 reacts with hydrocarbons to produce CO2 and H2O.

[0030] Another possibility is that at least a portion of the blast furnace gas is supplied to at least one external device. This external device is not part of the blast furnace or directly associated with it. It could be located in or even outside the steel plant. In this external device or plant, the blast furnace gas could be used as fuel for combustion or for other chemical purposes. Furthermore, it is conceivable to utilize only the residual latent heat of the blast furnace gas. Attached Figure Description

[0031] Preferred embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of a complete set of blast furnace equipment according to the present invention for implementing a method for operating a blast furnace. Detailed Implementation

[0032] Figure 1 A blast furnace assembly 10, including a blast furnace 12, is shown. The top 16 of the blast furnace 12 typically receives coke charge 18 and ore charge 20, while the bottom 22 typically receives pulverized coal 24 and oxygen-enriched gas 26. For example, the oxygen-enriched gas may have an O2 concentration of 95% and an N2 concentration of 5%. At the bottom 22, pig iron 28 and slag 30 are extracted from the blast furnace 12. The operation of the blast furnace itself is well-known and will not be described further herein.

[0033] The blast furnace unit 10 further includes a gas recovery pipe 40 for recovering blast furnace gas from the blast furnace 12. For example, the recovered blast furnace gas may have an N2 concentration of less than 5%, a CO and CO2 concentration of approximately 40% each, and an H2 concentration of approximately 15%. More generally, the blast furnace gas may have an N2 concentration of 0-50%, a CO and CO2 concentration of 20-50% each, and an H2 concentration of 2-25%. It is fed into a gas recovery piping system 42 including a distribution valve 44. The blast furnace unit 10 may include a gas purification device 43 arranged between the gas recovery pipe 40 and the distribution valve 44 for purifying the gas recovered from the blast furnace 12, primarily for removing particulate matter from the gas, and possibly also for condensing some of the steam contained in the blast furnace gas. It should be noted that the above concentrations refer to the dry components of the blast furnace gas. However, the blast furnace gas may also be wet, i.e., it may contain moisture.

[0034] At the distribution valve 44, at least a portion of the recovered blast furnace gas is directed to the mixing chamber 48 via a first supply conduit 46. The mixing chamber 48 is provided with a second supply conduit 50 for supplying hydrocarbon-containing gases (e.g., coke oven gas and / or natural gas and / or biogas) into the mixing chamber 48. Within the mixing chamber 48, the blast furnace gas and the hydrocarbon-containing gases are mixed together to form a gas mixture. This gas mixture is then fed into the reactor 56 via a third supply conduit 52, which may include a blower 54. Energy 53 can be added to the reactor 56 to sustain the reaction and heat the gas mixture. Energy 53 can be supplied to the reactor directly or indirectly. The energy can be any type of energy, such as electrical energy using an electric arc, plasma torch, or resistor, but advantageously, it can be obtained from the combustion process of the fuel gases in the burner 57. The gas mixture is typically compressed. Alternatively, the two gases can be compressed separately and then mixed. In reactor 56, the gas mixture is heated to a high temperature, thereby subjecting the gas mixture to a reforming process. In this case, the reforming process is mainly a dry reforming process based on the following reaction: CO2 + CH4 → 2H2 + 2CO. In this example, within reactor 56, at 800... ° C and 1500 ° A dry reforming process is performed at temperatures between C and [temperature range missing] without the need for a catalyst. Alternatively, a catalyst can be used, for example, by supplying a catalyst to reactor 56.

[0035] The generated synthesis gas is then sent back to the blast furnace 12 as a reducing gas via the fourth supply pipe 58, either at the height of the tuyeres or at the height of the lower furnace body.

[0036] When syngas is injected at the same height as the vent, it is injected together with auxiliary fuel 24 and oxygen-enriched gas 26. The syngas is at least 800... ° It is introduced at a temperature of C, while oxygen-enriched gas 26 is usually at ambient temperature, but it can also be at a higher temperature.

[0037] While the use of oxygen-enriched gas 26 increases the productivity of blast furnace 12, it may potentially lead to some difficulties. On the one hand, it can cause an increase in flame temperature in the swirl zone of blast furnace 12 because the flame is not cooled by nitrogen. On the other hand, the top gas temperature may decrease due to the significantly reduced heat transfer via nitrogen and thus the greatly reduced heating of cold charge. To address these issues, a flow control valve 47 is installed in the first supply pipe 46, through which the ratio of blast furnace gas to fuel gas can be adjusted. Generally, an overstoichiometric ratio is used so that the syngas can contain unreacted blast furnace gas. In particular, the CO2 and / or H2O concentrations of the syngas are increased. On the one hand, this additional blast furnace gas introduces additional latent heat into blast furnace 12, which helps to increase the top gas temperature. On the other hand, the CO2 and / or H2O contained in the syngas can react with C in blast furnace 12, generating CO and / or H2 in an endothermic reaction, which reduces the flame temperature. In particular, the top gas temperature and / or flame temperature can be monitored, and the ratio can be adjusted to control at least one of these temperatures and keep them within a desired range. At the distribution valve 44, at least a portion of the recovered blast furnace gas can be directed via a fifth supply line 60 to the burner 57 of the reactor 56 to supply the energy 53 required to heat the gas mixture and sustain the reforming reaction. Alternatively or additionally, it can also be used in a burner to heat the blast furnace gas in the first supply line 46, the coke oven gas in the second supply line 50, or the synthesis gas in the fourth supply line 58. In the burner 57, the blast furnace gas is preferably burned with oxygen 64 to generate a high CO2 content containing exhaust gas 66. Exhaust gas 66 may have a composition of, for example, 80% CO2, 15% H2O, and 5% N2. The exhaust gas can be collected and supplied to a cooler 68, where it is condensed and cooled, thereby further increasing the CO2 concentration, for example, to 95%. Therefore, it can be used for carbon capture and storage (CCS) at storage site 70, or it can be used, for example, for synthesis gas generation in a chemical plant 72.

[0038] Another portion of the blast furnace gas is supplied via a sixth supply pipe 62 to an external plant 74, which is neither part of the blast furnace nor directly associated with it. This external plant can be located within the steel plant or even in another facility outside the steel plant. In this external plant 74, the blast furnace gas can be used, for example, as burner fuel or for other chemical purposes.

[0039] Explanation of reference numerals in the attached figures: 10 Blast Furnace Complete Set of Equipment 12 Blast Furnace 16 top 18 Coke Packing 20 ore packings 22 bottom 24 auxiliary fuel 26 oxygen-enriched gas 28 pig iron 30 slag 40 Gas Recovery Pipe 42 Gas Recovery Piping System 43 Gas purification equipment 44 Distribution Valve 46 First Supply Pipeline 47 Flow control valve 48 mixing chambers 50 Second Supply Pipeline 52 Third Supply Pipeline 53 energy 54 Hair Dryer 56 reactors 57 burner 58 Fourth Supply Pipeline 60 Fifth Supply Pipeline 62 Sixth Supply Pipeline 64 Oxygen 66 Exhaust Gas 68 Cooler 70 storage locations 72 Chemical Plant 74 External Factories

Claims

1. A method for operating a blast furnace, the method comprising: - Collect blast furnace gas from the blast furnace (12), the blast furnace gas being a gas containing CO2; - Combining blast furnace gas with fuel gas to obtain a gas mixture, wherein the fuel gas is a gas containing hydrocarbons; - Subjecting the gas mixture to a reforming process to generate a synthesis gas containing CO and H2; and - At least a portion of the synthesis gas and oxygen-enriched gas (26) are fed into the blast furnace. Wherein, the blast furnace gas is combined with fuel gas without undergoing initial decarbonization after leaving the blast furnace; the blast furnace gas is combined with the fuel gas at an overstoichiometric ratio, such that the syngas contains an excess portion of blast furnace gas; and the overstoichiometric ratio is adjusted to control the flame temperature of the blast furnace (12).

2. The method according to claim 1, characterized in that, The blast furnace gas is combined with the fuel gas at an overstoichiometric ratio prior to the reforming process.

3. The method according to claim 1, characterized in that, The blast furnace gas is combined with the fuel gas in a stoichiometric ratio before the reforming process, and the additional blast furnace gas is combined with the synthesis gas after the reforming process.

4. The method according to any one of claims 1 to 3, characterized in that, The oxygen-enriched gas (26) contains at least 60% O2.

5. The method according to any one of claims 1 to 3, characterized in that, The oxygen-enriched gas has a concentration of less than 100. ° Temperature C.

6. The method according to any one of claims 1 to 3, characterized in that, The synthesis gas is at least 800 ° The temperature of C is fed into the blast furnace (12) at one or both of the tuyeres height level or the lower furnace body height level.

7. The method according to claim 6, characterized in that, The synthesis gas is at least 1000 ° The temperature of C is fed into the blast furnace (12) at one or both of the tuyeres height level or the lower furnace body height level.

8. The method according to any one of claims 1 to 3, characterized in that, The stoichiometric ratio is also adjusted to control the top gas temperature of the blast furnace (12).

9. The method according to any one of claims 1 to 3, characterized in that, In addition to the synthesis gas and the oxygen-enriched gas (26), auxiliary fuel (24) is also fed into the blast furnace.

10. The method according to any one of claims 1 to 3, characterized in that, A portion of the blast furnace gas is burned with oxygen (64) to produce exhaust gas (66).

11. The method according to claim 10, characterized in that, The exhaust gas (66) is condensed and cooled.

12. The method according to any one of claims 1 to 3, characterized in that, A portion of the blast furnace gas is burned in the heating device (57).

13. The method according to claim 12, characterized in that, The heating device (57) is used to heat the blast furnace gas, the fuel gas, the gas mixture and / or the synthesis gas.

14. The method according to claim 10, characterized in that, At least a portion of the exhaust gas (66) is used for carbon capture and storage and / or carbon capture and utilization.

15. The method according to claim 10, characterized in that, At least a portion of the waste gas (66) is used for the generation of syngas.

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